Autonomous Beach Cleaner

Abstract

As part of the Mechatronics course in the Master 1 Bruface program at the VUB and ULB universities, students were tasked with designing a robot capable of performing a predefined task. Group 4, composed of six students, chose to develop a Beach Cleaning Robot. The goal of the project was to create a robot capable of navigating on sand and collecting trash and debris.

The outcome of this project was a functional prototype capable of moving on hard ground and picking up objects in front of it. However, tests on sand have not been conducted. Videos demonstrating the robot's functionality are attached in this section.

Table of Contents

1. Project Motivation
2. Project Working Modes / Functionality / Requirements
3. State-of-the-Art and Patent Analysis
4. Conceptual Design
5. High-Level Design / Embodiment Design
6. Design of Subsystems
7. Integration Guide
8. Demonstration Project / Quick Start Guide
9. Project Review
10. Sustainability
11. Bill of Materials
12. Presentation of the Team
13. Project Repository

List of material used

Electronics

-2 transistors (MOSPEC TIP31A)

-3 1A diodes(1N5819)

-2 24V motor()

-2 6V motor(JGB37520)

-bunch of wires(>100)

-1 arduino Uno

-2 driver(VMA409)

-3 Distance ultrasonic sensors(HC-SR04)

-1 H-Bridge()

-2 Protoboard

-2 soldering boards

-soldering station + soldering wire

Mechanical

-26+0+72+16+15=129 M3 25mm bolts and 26+24+144+16+12=222 M3 nuts (box+roller+wheels+topbox)

-24cm of M3 threaded bar

-2m of M8 threaded bar

-10 M8 nuts

-10 M8 rondelles

-6 grosses rondelles

-4 wood cylinder to fit in the PVC pipes

-1 bathcarpet with holes

-Stapples

-14 angle brackets

- 13 of 32mm PVC pipe

-6 pullies (dimensions? 2.5teeth width)

-2 belts + 1 belt (dimensions?)

-18 ball bearings (SNR 608ZZ)

-72cm of 8mm not threaded steel rod

-6 wheels ()

-1.15 m^2 of laser cuttable wood (MDF 4mm)

-0.18 m^2 of laser cuttable wood (MDF 6 mm)

-wood glue

-hot glue

-vinyle

-1 shoe box

-1 small section of grid

-1 wooden comoposed shaft coupler

-1 20mm long nuts used as shaft coupler

Problem to Solve

Every year, in the world, around 8 to 12 million tons of plastic enters the oceans[Sur]. Although the effect of this worldwide plastic pollution on nature is complex, its main impact is a decrease of the biodiversity, leading to poisoning, entrapment, and often even death of animals. Some of which are already endangered. Furthermore, this plastic is difficult to biodegrade, taking often more than 400 years to decompose. Since 2015, more than 6.9 billion tons of plastic waste have been produced. About 9% has been recycled, 19% has been incinerated and 50% has been accumulated in landfills or in nature and in the oceans.[OEC22] The biggest signs of this plastic pollution is the Great Pacific Garbage Patch [Nat]. This patch is nearly three times the area of France, composed of scattered small floating plastic fragments, and larger debris. Although some projects, such as the Ocean Cleanup, are in development to collect and recycle the waste, these solutions need huge foundings and are difficult to deploy[Mag].

On the beaches, 73% of the trash is plastic: cigarette filters, bottles, caps, food packaging, polystyrene bags, and much more. Collecting this plastic before it gets washed away by the tide is an interesting addition for public policies on plastic regulation. The fully automated beach cleaners can reduce human labor, money, and improve efficiency. They are an excellent solution for public environmental organizations, as well as private sectors like restaurants, hotels and event organizers, helping them to reduce their plastic waste.

Persona Identification :

The beach cleaner is designed to meet the specific needs of various groups and organizations committed to preserving beaches and ensuring a clean and welcoming environment. The main potential customers include:

Local Governments : The local governments seek for fast and effective products, they need to keep their beaches clean for both residents and tourists. Due to their larger budgets, they can afford larger and more complex products. However, these solutions must follow environmental rules, which are becoming stricter every year.

Non-Governmental Organizations (NGOs) : "Non-Governmental Organizations focus on protecting the environment and the biodiversity, reduce pollution, and keep beaches clean by hiring volunteers or employees and by using cleaning machines. These NGOs often collaborate with local communities, governments, and private sectors to implement solutions. They require affordable products, environmentally friendly and that are easy to use since some volunteers might not have a specialize background.

Event Organizers : Event organizers that hold large events on beaches, which can generate waste, need fast and efficient products to restore the beach to its original state. Since there might be decorations or small spaces on the event places, the robot must be move easily and work in small spaces. Depending on the organizer, the budget might vary from limited to large.

Small Businesses : Smaller businesses such as small restaurants, different sports companies or chairs rental businesses might have a more limited budget, so cheaper products must be more suitable. Moreover often, those places are crowded by people and have very small spaces, in between the chairs for example, requiring a small and agile robot. The product must also be user-friendly, ensuring that all employees can use it easily.

Functional Analysis

The basic requirements for the robot are to be able to navigate on the beach which implies moving forward and turning in the sand. Moreover, it must be able to pick up and store trash of various sizes, while filtering the sand and replacing it on the beach. It must also be equipped with an obstacle detection device. In addition, it must be able to determine when it is approaching the boundaries of the beach, either the water side or the hard ground. Furthermore, the picking mechanism must be stoppable at any time, to limit power consumption, while the robot does not need to pick trash.

Use Case

The robot is deployed to a designated area of the beach that needs cleaning. It sieves through the sand, collecting trash along the way. The sand is filtered either during trash collection or after the trash has been picked up. When the robot detects a significant obstacle, it avoids it. After completing its cleaning task, the robot stops, and the trash storage compartment is emptied. The robot is then either stored or moved to another location.

Basic Functions of the Device

The different required function for the robot are listed in the Figure 2.1

Requirement List

The functional analysis resulted in the requirement list illustrated by the Figure 2.2. The first requirements for dimensions are there to assess transportability of the device, along with the weight requirement and are related to requirement 26. Requirements on kinematics ensure the maneuverability on sand and a minimum speed. Constraints on materials have been added (23-25) ensuring that the material resists the conditions of the beach (high humidity, salinity, abrasivity of the sand, ...) and also affect how the robot is conceived and divided (insulation of electrical components, ...). Given the ecological aspect of the project, requirements on the impact of the robot on the wildlife and its ecological impact have been added. The impact of the use of the robot should be minimal, the material should be recyclable, or the pieces reusable. Although other energy sources could be used, electricity has been considered the only possible option for similar reasons, and its easier use on this scale of project, leading to requirements 11, 22. Constraints on the picking mechanism have also been developed to better quantify the needs, in the form of the minimal and maximal size of the collected trash, the filtering rate of the robot, the storage capacity, and the time needed to empty the robot. Requirements on the detection of obstacles have also been added (12, 13, 14), and on top of that, the robot should avoid going into the sea. Additional requirements such as quietness and low cost have been included in the chart.

Priorities are also included going from F0 to F2, with F0 being an imperative need, F1 a not negotiable but still flexible need, F2 a negotiable need with moderate negotiability.

Eco-Design

Firstly, since the robot is used with electricity, and in areas with a lot of sunlight, solar panels could be added on top of the robot, making the robot able to work longer, and even indefinitely if the power consumption is low enough. Unfortunately, their integration is not that easy, and the surface area on the robot is limited. Considering this fact, the use of reusable battery is a must. A good conjunction of these two aspects could be to have a recharge station, disposing of other batteries to switch the batteries when the current one is low. Adding solar panels on top of this station would allow to recharge the robot with a larger area of solar panels, and not make the robot heavier due to the panels. This would also mean adding an automatic way of switching batteries. Finally, the recharging station could help the robot orient itself on the beach, with tracking technology, and help him regain the station, with wireless communication. The main downside is that in case of dark weather the normal operation could not be conducted, unless an additional power supply is available. However, concerning the developed prototype in the mechatronics course, only power supplies of the fablab were allowed to be used.

Secondly, the reparability of the final product and the prototype should be assessed. The different sections of the module should be easily taken apart, meaning that permanent bounds such as glue or rivet should be avoided. Nuts and bolts are therefore preferred. The full assembling process of the robot is developed in later sections. For the prototype, the same idea has been developed, using bolts and nuts as much as possible.

Finally, the materials used for the developed product should have the minimum impact on the environment, thus meaning that on its full life cycle, from the production, transport, to the use and disposal of the pieces. This is quite difficult to evaluate since some of the characteristics of the environment are complex (sand, humidity, ...) and affect the life of the different pieces. However, an estimation for the global product will be done. For the prototype, adjustment along the conception had to be made, to limit the use of 3d printing and using more laser-cutting.

Conclusion

In conclusion, the goal of this project is to develop a robot capable of picking up trash on the sand while respecting, as much as possible, the aforementioned requirements. However, during the development of our prototype, some flexibility will be allowed, unlike the final product. The aim of the prototype will, therefore, be to implement a working mechanism as proof of principle. Special attention will also be given to the environmental impact of the project.

State of the Art

There exists a variety of different beach cleaners on the market nowadays. To compare them efficiently, the designs are sorted into different groups, based on similar characteristics. The different groups are listed in the Figure 3.1.

The description of the categories are :

1. Manual cleaners : Cleaners that do not contain any mechanical or electrical piece. They are small and lightweight to be towed by a person.
2. Walk Behind : Motorized cleaners that move on their own but must be directed by a person walkingbehind. They are usually heavy.
3. Tractor Towed : Very heavy and large mechanisms can be only towed by tractors. Their large sizepermits a high filter rate of the sand.
4. Self Propelled : Heavy vehicles that are driven by a person.
5. Remote Controlled : Normal sized electric cleaner that can be controlled from distance with a remote.

The different categories of beach cleaners are compared based on multiple criteria. First, the noise level and the size are two important aspects to ensure a low disturbance of the nearby people. Then, a lower weight permits an easier transport from one beach to another once the work is finished. Moreover, the automatic criterion asserts how much assistance is needed from a person to ensure the correct working of the robot. Renewable energy usage is important to decrease the environmental impact of the robot. The minimal trash size, the storage capacity and the filtering rate are key criteria to ensure that the robot picks all type of trash, can store as much of it to decrease the number of times it needs to be emptied, and can filter a higher area faster. Finally, the price of the robot permits to determine the range of customers buying the product.

Based on the criteria and groups, the comparison table in the Figure 3.2 was created.

After analysis, the vast majority of the beach cleaners are heavy and large products, designed for high areas applications. Those products are generally very noisy, and difficult to transport without assistance. Moreover many of them do not use renewable energies.

However, there is an opportunity in the current market for smaller beach cleaners, designed for hotel chains or restaurants, that aim to clean smaller areas without disturbing their customers. A small and lightweight robot is suitable for this application since it will be able to move easily between the different obstacles such as decorations or chairs. It will also be easily transported and stored by the employees. An automatic robot reduces the time and resources spent by the employees on the product. The usage of electric energy ensures an easy recharge, a quieter operation, and no emission of CO2. And finally, it's reduced size permits a reduced costs, which will suit better for lower budget companies.

Patent Analysis

Seeking to deploy this product only in Belgium in a first time, and on a larger time-scale in the European Unions, patent analysis has been conducted on the Espacenet data base with combinations of words such as "Beach Cleaning Robot", "Autonomous" and so on. This resulted in a number of patent, and after verifying their status and their relevance, the Table of patents from the Figure 3.3 was created.

The analysis of three of these patents is shown in the attached Figure 3.4.

After analyzing the patents it was concluded that there is no freedom to operate. In fact, there are many designs patented, with very specific claims and for specific mechanism. However the global concept of such a robot is not patented. These patents also allow to see what means have been developed to tackle the various functionalities needed. Most of these designs use wheel or tracks a mean of locomotion while the waste collection systems are mainly conveyor belts and digging shovels. Energy is often supplied through solar panels and batteries. These patents can be used as inspiration as long as the resulting product does not fall under their claims.

For the various functions of our robot, we have identified the challenges we need to address. We have carefully considered different methods for enabling the robot to move efficiently across sandy terrain, as well as for detecting obstacles, water, and tracking its position. Additionally, we focused on ensuring the protection of both electronic and mechanical components to prevent damage from environmental factors such as sand and moisture. We also explored the most effective waste collection and storage systems, as well as energy solutions to power the robot, ensuring it remains functional and sustainable throughout its operation.

To implement the different functions, implementation ideas have been developed.

Obstacle Detection and Position:

1. Moving Plate System: A bumping system that activates a button when it comes into contact with an obstacle, triggering the robot to turn at that moment (cost-effective, reliable).
2. Reflectivity Captor: Detects water by measuring the amount of light reflected off the surface, with water reflecting less light than dry surfaces.
3. Ultrasonic Sensor: Detects obstacles by emitting sound waves and measuring the time it takes for them to reflect back (expensive, easy to manage).
4. Camera in Front of the Robot: Detects obstacles and water by capturing visual data and using image processing to identify objects and distinguish between water and other surfaces (most expensive but more versatile).
5. Humidity Sensor: Identifies areas with increased humidity, which are likely near water sources. This information helps the robot avoid water to prevent potential damage to its components (smooth and reliable operation in beach environments).
6. Lidar: Scans the environment, creating a 3D map of obstacles in its path. This allows the robot to navigate effectively by identifying and avoiding obstacles with high precision (can be used in complex and dynamic beach environments).
7. GPS: GPS coordinates guide our navigation and ensure the robot avoids areas close to water. This dual functionality allows the robot to maintain safe and accurate movement across the beach while staying away from moisture-prone zones that could damage its components.
8. Encoder: Provides precise data on distance traveled and speed, enabling accurate navigation and control. This ensures the robot can move effectively across sandy terrain while maintaining a clear understanding of its position relative to its surroundings.
9. Accelerometer: Helps determine changes in movement and orientation, providing additional data to ensure stability and accurate navigation. This is particularly useful on uneven sandy terrain, where maintaining balance and proper positioning is critical.

Collecting Waste System:

1. Rollers and Moving Stairs: Consist of a fixed part and a mobile part that lifts the debris, while the rollers help push the debris towards the collection area (not patented, avoids accumulation of sand, but too complex with too many pieces).
2. Picking Arm: Grabs the debris by using a mechanical gripper or claw to lift and collect the waste (not continuous, slower).
3. Digging and Vibration Filter: Uses a digging mechanism to loosen the debris from the ground, while vibration helps separate finer particles from the waste, making it easier to collect (more vibration means higher risk of damage; the waste might not go up unless additional support is added).
4. Roller Plus Conveyor Belt with Holes to Filter: Helps collect debris by using the rollers to push the waste onto the conveyor belt, which then transports it to the trash (easier to assemble, but needs testing).

Here’s the revised version for managing sandy terrain:

Managing Sandy Terrain:

1. Wheel: A 3D printed wheel with a wooden support, using a wooden frame to provide stability and structure. This design allows the wheel to move effectively across various surfaces, with the precision of 3D printing and laser-cut wood to ensure accuracy.
2. Flying: Uses a propulsion system, such as drones or rotors, to lift the robot off the ground, allowing it to move across the terrain without physical contact (expensive, requires assistance to move, not fully autonomous).
3. Tank Track: Utilizes continuous rubber tracks instead of wheels, providing better traction and stability on sandy or uneven terrain while distributing the robot’s weight more evenly (increased friction, more complex mechanical device).

Trash Storage:

1. Trash Bag: A lightweight, removable storage container for collected debris, allowing for easy disposal and replacement. It's easy to pack and light.
2. Removable Tank: A detachable container used to store collected waste, providing more capacity than a trash bag and making it easier to empty and replace when full. Although more cumbersome, it offers a simpler design for the removal mechanism.
3. Trailer: A detachable storage unit that provides additional capacity for collected waste. It attaches by one or two points on the robot, offering more space but potentially reducing stability due to its size and weight.

Protection of the Mechanism from Sand and Humidity:

1. Encasing of Electrical Components and Mechanism: Enclosing sensitive parts in a durable, sealed casing to shield them from water, sand, and other environmental factors. This ensures longevity and reliable operation in harsh conditions.
2. Coating: Applying a protective layer, such as a conformal coating or epoxy resin, over electronic components. This shields them from sand, moisture, and corrosion, allowing for optimal functionality and durability in beach environments.
3. Filters: Placing filters over moving parts or openings to block fine particles while still allowing airflow or movement. This helps keep the mechanical systems operational, preventing damage caused by sand accumulation.

Turning System:

1. Differential Rotation of the Front Wheels: Independently controlling the left and right wheels allows the robot to turn by varying their speeds. This provides more maneuverability, enabling sharper and more flexible turns.
2. Ackermann Steering System: Uses a mechanism where the front wheels are turned at different angles, ensuring smooth and sharp turns. This system ensures that all wheels follow the same path, ideal for precise navigation.

Preliminary Concepts

We have thoroughly evaluated various design approaches for the robot's functionality and performance. To determine the best solution, we developed three distinct concepts, each incorporating different systems and configurations. By analyzing the performance, feasibility, and efficiency of each, we were able to select the most suitable design to meet the project’s goals.

First Concept

This design features tracks for movement, ensuring the robot can navigate diverse terrains. A camera is integrated for obstacle and water detection, enabling smooth operation in dynamic environments. The robot’s position is tracked using an accelerometer, while sensitive electronics and mechanical components are securely housed in an isolated room to protect them from external elements. For waste collection, rotating stairs and a roller mechanism are employed, with an integrated bin for debris storage. Energy autonomy is achieved through solar panels and batteries, ensuring sustainability and functional efficiency for waste management.

Second Concept

In this design, the robot uses wheels for movement and a bumping system for obstacle detection. A reflectivity sensor detects water, ensuring the robot avoids moisture-prone areas. The position is tracked with encoders, while the mechanical and electronic components are housed in an isolated room for protection. A rotating stairs and rollers system is employed for waste collection, with an integrated trash bin for storage. The robot’s power needs are met through solar panels and a battery, providing efficient energy usage.

Third Concept

This concept uses wheels for movement, complemented by a LIDAR system for obstacle detection. The robot utilizes GPS to detect water, while encoders track its position. The electronics are housed in an isolated room, with mechanical components protected by filters to prevent sand damage. The waste collection system includes digging and vibration mechanisms for debris separation, and a single-point attached trailer for waste storage. Solar panels, a battery, and a charging station ensure effective energy management, promoting sustainability.

Selection

After comparing the three concepts, we created a weighted scoring table based on key criteria, such as efficiency, cost, environmental impact, feasibility, and patent considerations. The results are summarized in the table provided.

First Concept

The first concept emerged as the most efficient choice due to its balanced performance in terms of cost, functionality, and environmental impact. The tank tracks provide excellent traction across varied terrains, ensuring stable movement on the beach. The integrated camera system offers dual functionality for both obstacle and water detection, enhancing the robot’s versatility. The use of an accelerometer for position tracking is both cost-effective and accurate. The isolated compartments protect sensitive components, boosting durability. The waste collection system—comprised of rotating stairs and rollers—is both effective and unpatented, ensuring originality. Additionally, the integrated trash bin offers practical storage. The combination of solar panels and batteries ensures energy efficiency and minimal environmental impact by utilizing renewable energy sources. Overall, the first concept proves to be a cost-effective, environmentally friendly, and high-performing solution for the project.

For the embodiment design, a distinction must be done between the final product and the prototype. This first section will detail the final product while the second about the prototype.

Final Product

3D Model and diagram:

The 3D model of the robot is shown in the Figure 5.8

On the Figure it is possible to see the tracks of the robot attached to the casing, the digging mechanism inside and the camera in front. The track systems are powered with 24V DC motors.

Material Analysis

To determine the materials needed for the beach cleaner, the model can be divided into four elementary subsystems, each produced with one type of material.

Picking Mechanism

The picking mechanism consists of an important part of the entire robot, the material must be the lightest possible, while being robust enough to resist to the weight of the trash.

This part will be in constant friction with sand, and humidity so abrasion, and humidity resistance are primordial. Furthermore, the machining process to make the pieces must be precise and cost effective since the picking mechanism is composed of many moving parts.

From those criteria the materials sets were filtered and the remaining materials are the metals, the polymers, and the composites.

To determine the constraint equation a simplified scenario was chosen, where a cantilever beam is constrained on one side and a force is applied on the edge of the beam. This is a simplified representation of the weight of the trash when it's picked up from the sand. The goal is to maximize the Young's modulus and minimize the density.

To determine the constraint equation a simplified scenario was chosen, where a cantilever beam is constrained on one side and a force is applied on the edge of the beam. This is a simplified representation of the weight of the trash when it's picked up from the sand. The goal is to maximize the Young's modulus and minimize the density.

The equations in the green section in the Figure 5.2 were used to find the precise material.

The material selection in the Figure 5.3 shows that four different types of materials are physically optimal. The beryllium alloys and the lithium metals are not suitable due to their toxicity, high environmental impact, poor recyclability and their scarcity.

The ABS and PA66 materials could be more suitable. Those are plastic materials, combined with carbon fiber to increase the durability. Although those materials are very light, stiff and durable, they are quite difficult to product, since they require carbon fibers and their recyclability is limited. The ABS based material will be chosen for the project since it has a higher availability than the PA66.

Casing

The casing composes a significant part of the robot. Therefore, the material must again have the lowest mass while being robust to handle the weight of the robot pieces without bending. In addition, since a high quantity of this material is needed, all plastics or polymers will be excluded to ensure the sustainability of the robot. Finally the material should resist to moisture heat, sand, erosion, removing wood-like materials from the list.

The remaining materials for the casing are the metals, composites and fibers.

To find the optimal materials, further constraints can be used. Since the material must resist to deformation and be lightweight, the Young's Modulus(E) must be maximized and the density($\rho$) minimized. The constraint equations are derived from the assumption that a square horizontal plates are the most subject to deformations due to the pieces weight. Thus an uniformly distributed force (f) is exerted in the center of a fixed plate of known length (a) and unknown height (h), creating a deflection.

The equation in blue in the Figure 5.2 were used.

In those equations appears the physical parameter ν. For the most common materials such as metals in this case, this value range from 0.25 to 0.35. Thus the term 1 − ν2 will ranges from 0.87 to 0.93, which in this case can be considered as a constant without much impact on the results due to the small variation.

The Image 5.4 was used to determine the right material, which is the aluminium 6061 T62, it is a recyclable and non-toxic aluminum alloy, widely produced in various shapes. This alloy is highly resistant to corrosion, making it ideal for creating a durable casing for the robot.

Power transmission

For the power transmission pieces such as the track pinions, shafts, rods and gears, the materials must have a high strength, be ductile to not shatter under load, not wear due to the friction, and resist to water, heat sand and erosion. Additionally, the materials must be suitable for manufacturing high-precision parts. The remaining materials after filtering are the metals and plastics or polymers. Although plastics can support less loads, they can be used for smaller load applications, thus the quantity of plastic used would also be low.

For the constraint equations, since the pieces require much less material but a high fabrication precision, the cost per unit volume must be minimized. Moreover, the pieces must handle a high load, thus the yield strength must be maximized.

The equations in red in the Figure 5.2 were used, and the material chart in the Figure 5.5, were used to determine the optimal material which is either low alloy steel or cast iron.

Track

The tracks must be composed of solid but flexible materials that can resist tension so the robot moves optimally on any type and shape of ground. The materials adequate for this are the elastomer, some flexible thermoplastics, and polymers.

No constraint equations were found to further filter the materials. So the choice of the materials were based on inductive constraints. First, the material must have a high yield strength to avoid irreversible deformation due to stretching. Then, the Young's Modulus should be minimal for the material to deform easily and adapt to terrain shape. Thus, the ratio Yield Strength/Young's Modulus must be maximized. Finally, since the tracks have an important size, the density should be minimized to reduce the weight.

The optimal materials are located on the top left part of the chart. Although many materials have suitable physical properties, natural rubber is chosen. This material has a lower environmental impact than the others, which are mainly synthetic, because it comes from a natural source. Moreover, natural rubber is biodegradable. However, its production also has downsides. The growing demand for rubber leads to deforestation, and in some regions, the biosphere is affected due to the usage of pesticides and chemical fertilizers. However, it is a sector that is becoming slowly more sustainable .

Manufacturing Process :

For the manufcturing of the small metllic pieces, iron casting is the best solution. For plastic and rubber components, compression or injection molding are suitable solutions. An finally for the casing of the robot, since it is mainly made of flat sheets, laser cutting is the fatest and most precise method. Some pieces however will also be bent on some parts.

Assembly :

The assembly steps are shown in the Figure 5.7. First, one side of the casing is assembled, then the picking mechanism is inserted before adding the other side of the casing. On top the motors are then added. After, the separting plate is inserted on the top and the batteries attached in the back. Then, the camera is added and the casing closed. Finally the moving tracks mechanisms are inserted to the external part of the casing.

Prototype

The fprototype is compose of the following subsystems:

The main box : Wooden assembled casing to place all the electrical and mechanical components.

Arduino : With all the main electronic components, in a sealed box on the top of the robot. This is the brain of the robot which controls every feature of the robot, it is linked to the actuators in charge of the motion device, the waste collecting system and the different sensors of the robot.

Six Wheels Differential Drive : Two wheels on each side are powered by a motor at the back of the robot. The motors are commanded by a dual chnnel driver to make them rotate in both direction and so the possibility of turning the robot to avoid an obstacle or continue the programmed track to follow.

Waste picking mechanism : the system is composed of a conveyor belt and the front roller to catch and store the waste. It is stored in a bin with a filter in order to evacuate the remaining of sand after the pick up.

The Figure 5.9 illustrates the subsystem chart, and 5.10 the 3D model of the robot.

Material Analysis

The casing is done in wood for a fast and more environmentally friendly prototyping. The parts that supported higher loads, such as the bottom plates, are thicker to avoid any important bending. After assembling all the robot, measurements the different plates were not affected by the weight of the pieces.

The motor shaft couplers in the picking mechanism are made from salvaged metallic pieces. Those pieces are able to sustain a higher torque in comparison with the plastic or wooden ones.

The axles are also made from metallic rods salvaged from old printers. They are equipped with rubber bands which permitted to fix the bearing attaches and avoid any slippage.

The bearing attaches are designed of multiple sheets of wood.

The motor attaches are made from a slavaged bent aluminum pieces.

The conveyor belt and cylindric rake are made from salvaged carpets shets and vynile.

The timing belts and metallic pulleys were found at the fablab.

a. Mechanical Systems

Manufacturing Processes And Materials For The Prototype

The manufacturing processes available in the FabLab are laser-cutting MDF and 3D printing. The most commonly used for this robot is laser-cutting due to its speed and the simplicity of the pieces to create.

MDF has many advantages, including its low density (680 kg/m³) and low cost. Although MDF is less recyclable than PLA from 3D printing, it is strong and stiff enough for the prototype of this beach cleaning robot.

Assembly

The robot is assembled using nuts and bolts. Cross-like shapes are used to fasten the different pieces together and ensure proper alignment. Most of the shafts are threaded rods, making assembly easier with nuts and allowing for easy disassembly when needed.

Subsystems

Trash Picking System

Following the original concept proposed, the following model of the picking system has been developed.

The subsystem is composed of two wooden reinforced structures, with pre-drilled holes for the addition of ball bearings for the rollers. Two rollers are placed at the bottom, supporting the conveyor belt, which spans the entire width of the system. Additionally, one roller is added at the front, on which flexible cloisoning is fixed. The four cloisoning pieces are made of vinyl, designed for floor covering, with various indentations to provide different levels of rigidity. This design helps both capture trash and propel it toward the storage box.

An additional shovel-like wooden component is placed in front of the mechanism. This component helps guide trash into the opening and the rollers while simultaneously filtering sand, thanks to the ridges on its sides.

The conveyor belt is made from a simple bath carpet, stapled at the ends to form a loop. Since the carpet features holes, sand is also evacuated during the lifting of the trash, ensuring effective separation and collection.

i. Requirements

The requirements applicable to the digging system are:

1. Maximum Trash Size: The system should be able to pick up bottles with a maximum size of 30 cm in width and 10 cm in height.
2. Minimum Trash Size: The system must also be able to collect objects as small as a bottle cap, with a minimum size of 3 cm in width and 1 cm in height.
3. Filtering Rate: This is indirectly related to the speed of the robot and its width. Initially, the target filtering rate is 800 m²/h.
4. Storage Capacity: Since this is a prototype, this requirement will be ignored.
5. Time to Empty: The time required to empty the collected trash will also be ignored.

It is also important to note that the wildlife safety requirement is applicable here, ensuring no harm to wildlife during the robot's operation.

ii. Conceptual Design

As developed in the previous sections, the two main conceptual designs considered for this have been the Rollers and Conveyor Belt, or the Rotating Stairs.

The initial design planned for the prototype was the Rotating Stairs mechanism. This design needed a lot of different pieces with specific forms and was difficult to realize. In fact, to make these pieces, 3D printing could have been used, but this would have taken a non-negligible amount of time, cost money in printing filament, and would have had too big an impact on the environment, therefore being counterproductive.

The mechanism would have dug into the sand, lifting the trash one step at a time, slowly bringing it up, while filtering the sand by letting it fall in between the claw-like rotating stairs. The trash would also have been assisted by rollers in the front and in the back of the mechanism, and in the end, would have dropped into the trash storage part.

This design had the advantage of not being patented and being original, and could have been adapted to laser-cut MDF wood to produce a proof of concept. It would, however, also have required a lot of materials such as ball bearings, and so on, and would possibly not have been resistant enough to lift weights. Moreover, the assembling process would have been cumbersome, and any mistakes could have ruined the entire mechanism. However, this principle has been kept for the Design Methodology part of the project.

The second envisioned mechanism was the Roller plus Conveyor Belt mechanism. This design requires fewer different elements but also has major downsides. In fact, finding suitable material for the conveyor belt was extremely difficult. After tests were conducted with vinyl, the conclusion was made that this material was too rigid for our prototype and that another solution had to be found. A simple carpet bath was finally found, which was more flexible, had a good amount of texture to bring trash up, and had holes that could help the sand be filtered while the trash was conveyed.

The idea of this mechanism is that objects pushed inside by the rollers would be propelled onto the conveyor belt, and would end their course in the trash storage part. The ridges in the front shovel-like part help prevent sand from being pushed into the system, while the conveyor belt is also holed. In the trash storage part, a final filter is also present to let any sand that would be in the trash drop.

iii. Embodiment Design

The following pieces constituted the design:

1. 2 Rollers with flexible cloisoning
2. 2 Rollers to support the conveyor belt
3. 2 Reinforcing structures on each side
4. 8 Ball bearings (reference in the list of supplies)
5. Conveyor belt
6. 2 Pulleys to mechanically link the upper rollers and the lower rollers, along with gears
7. 1 Additional shaft
8. 2 Different-sized gears
9. 1 Belt
10. 2 Pulleys
11. 12 M8 nuts
12. M8 Steel rings

Manufacturing of Pieces

A) The Rollers

These rollers were made from PVC pipe, in which threaded M8 shafts have been fixed. Additional metal rings have been added to the extremities of the pipes to seal them up.

In the top rollers, 6 additional holes have been drilled with a size of M3. Six threaded M3 rods (4 cm long) have been placed in these holes, while 4 pieces of vinyl have been cut and pierced to attach them, as shown in the following picture.

Moreover, one of each roller (top and bottom) has longer threaded rods to add the pulleys.

B) Reinforcing Structures

These two structures were simply laser-cut. They are useful for guaranteeing the stability of the collecting system and maintaining the correct distance between the shafts to keep the conveyor belt under tension.

C) Conveyor Belt

The conveyor belt was cut into a rectangle of 30 cm in width and 50 cm in length. It was assembled by attaching both extremities of the width with staples, leaving a double section of around 5 cm and adjusting it to have the right tension.

D) The Gears

Two gears are used to transmit power from the lower shaft of the conveyor belt to the roller in front. The driving gear has 15 teeth, and the driven one has 30 teeth, allowing for a larger torque to be transmitted.

E) Shaft Couplers

The first shaft coupler was made of one 20 mm long nut (metric 8) so the shaft is screwed, and two screws tighten the motor shaft. However, achieving and maintaining perfect alignment of the two shafts during rotation is difficult.

The second solution is the use of a laser-cut piece to make the transition from the motor to the shaft via a nut.

iv. Final Assembly

First the conception of the rollers, the threaded rod used as shaft are screwed in a cylinder of wood (made by digging a hole with a hole saw, assembly of layer of lasercuted disks could be a good alternative too) fitting in the pvc pipes such that the wood doesn't slide in the pvc. On one side of the pipes the shafts are left longer, to integrate after the needed mechanical peces (pulleys,gears,motors) to power this system. The front grid and the back upper pvc pipe can be fixed to keep the assembly all togheter for the first tests

Once the rollers made, the bearings putted on the shaft match in the holes of the reinforcing structure and the insides plate of the robots so the mechanism can be screwed. With the long shaft protruding from one side of the plate, the little gear is fixed on the lower shaft, wich is also attached to a motor.

For the front rollers, the shaft pocess only a puller, the belt trought witch the roller is powered is attached to another shaft fasten between the inner plate and the side plate of the robot.

The second roller link to the conveyor belt is only link to the shaft by a shaft coupler between the second motor and the roller's shaft.

v. Tests

Preliminary tests can be made by hand without fixing the larger plate, and in a second stage, to check if the gear/pulley assembly is working. Tests were made using a temporary piece to hold the additional shaft on which there is the large gear and a pulley.

After testing, we concluded that the system was working with one roller, and the second one was not added. The prototype managed to lift different trash of various weights and sizes. During the testing, cuts were made into the vinyl flexible parts to allow for better intake of the trash.

Motion Mechanism

Introduction

In order to move the robot on sandy terrain, a motion system with 3 wheels on each side has been designed. The system is symmetric on both sides and is composed of one 24V DC motor powering the first wheel. The middle wheel is also powered by a belt, and finally, the front one is free for turning.

To turn the robot, differential drive is used, where the wheels on one side rotate to make the turn, while the wheels on the other side remain still, allowing the robot to rotate to the correct angle.

i. Requirements

The requirements applicable to this part of the mechanism are the following:

1. Direction of motion
2. Displacement on sandy terrain
3. Velocity: Taking into account the width of the robot, the needed speed is around 2 km/h

The ability to manage sandy terrain is the main challenge of this mechanism.

ii. Conceptual Designs

The two concepts that stand out for this mechanism are the wheels and the tracks. Although tracks offer better performance, acquiring suitable tracks for this kind of application is difficult and expensive.

For the design methodology of the product, the mechanism chosen was the tracks. However, for the prototype implementation, wheels were preferred for the reasons explained above.

The first concept is equipped with 4 wheels per side and 2 tracks. The motorized wheel is at the top of a triangular-shaped wheel assembly.

The second conceptual design uses 3 wheels per side. The back wheels are motorized, and to reduce the pressure on each wheel and distribute the mechanical power, pulleys are used to transmit this power between the bearing shafts. The original plan was to have two belts per side to motorize six wheels, but excessive friction from the pulleys led to the abandonment of the last belts.

iii. Embodiment design

The following pieces constituted the design:

1. 24 wooden pieces with 8mm holes (CAD file available)
2. 24 wooden pieces with 22mm holes (CAD file available)
3. 24 steel holding pieces
4. 2 wooden boards
5. 72 M3 bolts
6. 144 M3 nuts
7. 6 12cm shafts with a diameter of 8mm
8. 6 plastic wheels
9. 12 wooden extensions for the wheels (CAD file available)
10. 60 wooden rectangular pieces
11. 36 4cm M3 threaded rods
12. 12 ball bearings

Manufactured pieces

A) The wheels

Six M3 holes were drilled into the wheels to extend them. The wooden extensions were fixed to the plastic wheels using the threaded M3 rods and bolts on each side. Additionally, 10 wooden rectangular pieces were added to each wheel and glued to each ridge.

B) The shaft bearings

By taking 2 wooden pieces with 8mm holes and 2 wooden pieces with 22mm holes, 2 nuts, and two M3 bolts, and assembling them with a ball bearing, simple shaft bearings were created.

iv. Final Assembly

For each assembly, the process is the same but symmetrically. In one plate, the two shafts powered by the motor are fixed, and the transmission of power is made by belts, which distribute it to both shafts. The third shaft is fixed on an independent plate, so the moving mechanism on one side just needs to be screwed onto the bottom of the robot. The motor is placed at the back of the robot, and the structure is assembled such that the shafts align with the holes made for this purpose in the side plates.

v.Testing

The tests were made separetaly form the other systems

vi. CAD Files

All the CAD Files of the differents sub-systems are available in the project repository

Trash Disposal

i. Requirements

The requirement applicable to this sub system are:

1. Trash Storage Capacity : 4000cm^3
2. Time to empty trash storage : 5 mins : This requirement will not be considered for the prototype as previously mentionned

ii. Conceptual Designs

The only considered Design was the simple box.

iii. Embodiment Design

The box was just made of a shoe box. In the bottom of the box, a hole was cut, and wire mesh was stappeld to let the sand flow out of the box and fal back in the sand.

iv. Final CAD Design

No modelisation was done for this part of the prototype ans according to the chosen shoe box, dimensiosn might change.

v.Testing

As seen in previous test, it works, it is a box.

b. Electrical circuit, sensors and software

i. Requirement

The realization of the electronic circuit must respond to the different demands of the robot:

1. Control the three ultrasonic sensors to detect any obstacles in front of the robot.
2. Power the two 24V motors attached to the moving mechanisms.
3. Power the two 6V motors of the picking system.
4. Power the Arduino through its input pin with 6V to 20V.

ii. Consideration of the components

a) Obstacle Detection

The use of an ultrasonic sensor was chosen due to its easy availability, low cost, and ease of implementation in Arduino code. Since the range of a single sensor's vision is limited, three sensors were attached to the front of the robot to maximize detection efficiency. The three sensors are triggered simultaneously, meaning all the 'TRIG' pins can be connected to the same Arduino output pin. However, the echo pins must be connected to different pins, as each sensor can return values at different times depending on the distance of the object.

The sensors were tested with the arduino and an oscilloscope. The figure 6.9. Where a trigger pulse was sent, then the length of the echo pulse was measured to determine the distance of the object. The further the object the longer the distance.

b) Motion Circuit

For the motion system, two motors are used for differential drive. Each motor drives two sets of wheels on each side of the robot. Since the required speed of the robot is 0.5 m/s and the wheels have a 12 cm diameter, the required RPM of the motors can be calculated.

The required rotating speed for the motors is approximately 32 RPM. However, the chosen motors should exceed this rotational velocity to ensure that the robot moves fast enough, even under higher load conditions.

To determine the torque of the motors, two approaches were used. First, using the equations described in Image 6.?

The second approach was to analyze research papers on moving vehicles on sandy terrain, with similar weights and dimensions to our robot. By extrapolating the results to our robot, a torque range from 0.8 to 1.3 Nm was expected, depending on the experimental results chosen. This aligns closely with the theoretical results obtained through the equations.

Since timing belts are used, the efficiency of each belt is expected to be 90% in the worst case. With two belts, a power loss of 81% is expected, increasing the torque needed to 1.6 Nm.

An additional safety factor of 1.2 was applied to ensure the motors have enough power, raising the final torque requirement to 1.9 Nm.

The motors used for this purpose have a no-load RPM of 68 and a stall torque of 5.5 Nm. These values are higher than the theoretical ones to ensure the safety of the electronic components, as the theoretical values are approximations.

Moreover, the characteristic curves of the motor, created from the datasheet, are shown in Image 6.10 which visualize that the operating point of the motors is around 44 RPM, 1.9 Nm.

The motors are powered and controlled through a dual-channel motor driver, which is directly connected to the 24V power supply.

A dual-channel encoder is attached to each motor to measure their rotational speed, which helps track the forward and rotational velocities of the robot, in addition to its position.

c) Collecting Circuit

This circuit is based on the use of controllable switches to turn the motors on and off, allowing the system to stop when the robot is turning or shut down.

The motors used are 6V motors, which are powerful enough to drive the subsystem. A potential alternative could be the use of 12V motors to provide more torque and counter the friction between the rotating rollers and the supporting plate more efficiently.

The second part of this subsystem is the controllability. A transistor is used for this purpose, based on the torque needed and the data sheets. The transistor must allow a specific voltage (at least 6V) and current (at least 1.5A max).

Finally, flyback diodes are used to prevent the no-load current from flowing through the transistor in the wrong direction, which could damage it. For the prototype, three diodes are used in parallel to distribute the passing current between the diodes.

d) Buck Converter

A controllable buck converter is used to power all the components. It converts the 24V input to 6V, which powers the two 6V motors and the Arduino. The converter can supply up to 3A, which is more than sufficient for the total consumption of the powered components.

v. Exact Component

Drivers ; VMA409 x2

Motion Motors ; 24V 37D Metal Gearmotors x2

Collecting Motors ; JGB37520 x2

Buck Convertor ; MP1584EN x1

Transistor ; TIP31A x2

Diodes ; 1N5819

Ultrasonic Sensor ; HC-SRC04 x3

c. Software

For the software, the Arduino provided is used and is sufficient for the prototyping of the robot. The code is written with the Arduino IDE, which provides useful libraries and facilitates the management of components due to its simplicity.

i. Requirements

The robot must be able to move in a straight line while picking up trash from the sand. Once an obstacle is detected, the robot must stop the picking mechanism, make a 180-degree turn, and continue its path in the opposite direction. For each obstacle, the robot alternates between turning right and left to sweep the whole area.

This results in the following use cases, in which the robot is placed on the beach, travels a certain distance in a straight line before stopping, or detects an obstacle and stops, turns 90 degrees, goes forward a small distance, turns another 90 degrees, travels the same distance, and stops at the same level as its starting point but slightly offset. Then the robot turns another 90 degrees in the opposite direction of the last turn, moves forward, and turns the same way 90 degrees. When repeated over and over, this would result in the sieving of an entire section of the beach, from the water to the end of the beach. Obstacles would only trigger the turn sooner than a normal pass of the robot, and the value of the distance at which the robot turns would be memorized to allow it to remain globally unshifted even when obstacles are considered.

ii. Design process and considerations of components

The code was developed in several parts: the picking mechanism, the motion mechanism, and the obstacle detection.

For the picking mechanism, the code was designed to enable or disable the output pin that controls the transistors. It was first connected to a simple LED instead of motors to ensure the functionality and avoid breaking any components if the circuit had issues.

For the motion mechanism, the encoder pulses were read for a certain duration. The pulses per rotation were divided by the time, and the speed of the motors was calculated. Then, by using a proportional regulator, the voltage of the motors was adjusted so they matched the desired speed. Another part of the code was designed to determine the correct speeds of the motors in order to move in a straight line or make a turn.

For the obstacle detection mechanism, a signal was sent to all three sensors, and their returned values were filtered. If the distance was too high, then the reading was considered incorrect, and the value was not taken into account. If the reading was within the desired range, it was kept. Finally, all the readings were compared, and if one of them was below the specified threshold, a turn was triggered

iii. Code flow diagram

The code flow diagram can be found in the figures 6.12 and 6.13

iv. Testing

The code was first tested by parts. First, the robot was elevated so the wheels did not touch the ground. This way, it was possible to test the integrity of the whole moving mechanism more easily. The code was updated to make the robot go forward and make 180-degree turns.

Then, the two motors were powered directly into the picking mechanism using the flyback circuit. Some objects were placed in front of the mechanism to verify if it could pick up the trash and store it.

Due to time limitations, the detection of obstacles was not entirely tested, although the sensor code for the distance was verified. The sensors were able to provide a relatively precise distance of the objects in front of them.

Therefore, the first full test of the robot was done by just alternating straight movement with 180-degree turns, while enabling and disabling the picking mechanism.

v. Provided code

The code for the robot is attached at the end of this section.

Now that the models for the sub-systems are created, they must be assembled.

Step1 : Moving mechanism assembly (Figure 7.1):

The firt part of the moving mechanim is the bearing attach. This piece is made form 4 wooden pieces attached together with bolts. Inside each attach is inserted a ball bearing with a salvaged rubber band, to prevent the bearing from moving or slipping inside its casing.

Then, the axles are assembled. The belt pulleys provided by the fablab are inserted into the the salvaged and cut metallic rods. Then on each rod is added other salvaged rubber bands. Finally two bearing attaches are inserted on the edges. The rubber bands are on each side of the attaches to prevent the rod from slipping, without constraining its rotation.

Once the 6 axles are finished, they are attached to the wooden plates. The attach is done with metallic sheets that were bent to follow the shape of the wooden attaches. This way, the attaches will not move once fixed.

Two axles are attache on the l shaped wooden plates and one single per square plate. The square plate is designed for the free wheels that are not powered by the motors.

Before fixing the axles, the belts are inserted and stretched.

Finally, the motors are fixex in the wide area of the L-shaped pieces, the fixation is made with bent aluminum sheets in which holes were drilled. The motor has another pulley inserted in the shaft and attache to the rest of the mechanism with a small belt.

Step 2 : Wheels assembly (Figure 7.2) :

The wheels assemby is based on existing smaller wheels, salvaged from old car toys. To add thegrousers, first 6 equidistant holes must be drilled into each wheel. Then the two wooden edges are inserte an fixed with threaded rods and botls an hex nuts. In total 36 rods were cut from longer pieces and used.

Then the grousers pieces were attached, two options were possible. First to attach them with other threaded rods, or to fix them with wood glue. Although the wood glue is a irreversible process, the wheels must in theory never be disassembled again. Moreover using again threaded rods would have been time consuming since 60 aditionnal rods were needed, and each rod had to be cut. In addition to screwing everything.

Step 3 : Picking and moving mechanism integration on the casing (Figure 7.3):

The picking mechanism is directly mounted to the casing. The roller and the cylinders are inserted on one side of the casing. Then the salvaged conveyor is added. And finally the second edge is inserted to fixate the whole mechanism.

Then the middle casing is inserted on the bottom plate, on which the moving mechanism are inserted.

On the right side of the robot, the picking motors are attached to the desired location, indicated by the cut holes. Those motors are fixated throug wooden supports and power the conveyor and the roller through a timing belt.

Step 4 : Electrical circuit insertion (Figure 7.4):

The electrical circuit must be done by following the schematic, and inserted in the designed space at the top of the robot. The ultrasound sensors are placed at the front of the robot.

Project Demo :

The demo of the autonomous beach cleaner is shown in the video above.

Quick Start Guide :

In order to make the different assembies, the detailed step by step method, used by the team, is listed in the section 7.

1. Make the pieces :
2. Download the files from the 3D folder and cut all the pieces. This projet was made from recupertion materials and laser cut MDF, so there are no 3D prints.
3. Assemble the motion mechanism
4. Assemble the 12 wooden attaches for the bearings.
5. Buld the 6 wheels axles by attaching the belt pulleys to the metallic rods, then inserting the wooden attaches on the sides.
6. Create the two powered moving mechanisms by attaching two axles on each L shaped wooden support. Link the axles with a timing belt.
7. Create the free wheels axles by attaching one axle on each square woodent support.
8. Insert the motor on each side and link it to the powered mechnism through an aditionnal belt.
9. Attach the 4 mehcanisms on the U shaped buttom support
10. Assemble the picking mechanism
11. Attach the cylindrical rake and the two tubes for the conveyor on a side plate of the picking mechanism
12. Insert the conveyor belt between the two cyclinders.
13. Add the second side plate to fix the whole mechanism.
14. Add the mechanisms into the casing
15. Build the bottom part of the robot.
16. Add the motion mechanism on the casing.
17. Insert the picking mechanism.
18. Add the storage box behind the picking mechanism.
19. Cover the top and sides with the adequate wooden plates.
20. Fixate all the plate with bolts and screws in the allocated spaces
21. The cover plates can still be removed by unscrewing the screws, in order to acces the mechanisms inside.
22. Assemble the electrical circuit
23. Connect the electrical components as shown in the circuit schematic, then add them on the top of the robot.
24. Power the robot :
25. Connect a 24V and minimum 4A power supply to the input pins of the circtuit. This voltages will be regulated adequatly with the buck converter to power the other components.

Although the project worked partially, some features have not been implemented. In fact, due to a malfunction in the arduino, it became impossible to reprogram it. Therefore, the last code will be forever encoded. This empeach us to make further testing of the robot, including operation of the robot with sensors, testing of the code and so on. However, tests had been conducted on all element separately, ensuring that the code worked for managing three ultrasonic sensor at once. Tests on the motors, with a proportionnal regulator for the speed had also been conducted and were concluent.

Moreover, the general project was rather ambitious and underwent multiple design iterations to balance efficiency and practicality. The initial design featured a lifting mechanism that operated by elevating objects one step at a time while separating sand but had to be abandonned, due to his complexity and his too heavy reliance on 3D printing, consuming time, ressources, and having a too big environmental impact, eventhough it was innovative. Due to these constraints, the team opted to pivot to a simpler design utilizing a conveyor belt system with a roller mechanism to push debris onto the belt. This heavily retarded the development of the project. The revised design reduced the number of components and assembly time while maintaining effectiveness. However, this shift required sourcing a suitable belt and testing its compatibility with beach conditions, such as sand resistance and load capacity. It also delayed massively the first tests that had to be conducted. The wheels also were a huge problem, to make them fit our application, in fact, we only add small wheels, and needed to enlarge them, with wooden laser cutted pieces. Moreover, the pullies where not exactly straight because they had to be enlarged to fit the shafts we had, and introduced a lot of stress and friction.

In addition, in the end, a lot of imporvisation had to be made to join the project alltogether and to meet the deadline, while still retaining some coherent overall choices.

To improve the project further, here are some ideas we had :

1. Adding oblique panels in front of the robot, to enlarge the intake
2. Adding tensioning rods on the belts of the pullies, to better tension them
3. Adding track on the wheels, to increase the friction on the ground
4. Replacing encoders with accelerometers, to avoid error due to inconstant slipping
5. The readings will also be easier since only one sensor will measure the accelertion and rotation. And the accelerometer can directly be inserted into the electrical circuit, contrary to the encoders who have to be attached in the movement mechanism.

Since the overall purpose of the project is to improve environmental conditions and reduce pollution, the sustainability of our design, in both its prototype and in its final concept, is essential.  

First, the prototyping aspect underwent a lot of evolution, and radical changes. In overall, recuperation materials have been used as much as possible. The metal shaft came from an old printer, while the vinyl was old pieces of junk. The meshed wire and the shoe box are also recuperation materials. Pieces of different types were found left and right, such as the bath carpet, and therefore necessitated adaptation of the plans. It also ensured to reduce the costs of the project bill. In definitive, although tests were initially conducted with 3D printing, in a second time, it was avoided as much as possible, resulting in the design of laser cut pieces, even for difficult applications such as shaft coupling. 

For the finished product concept, of the Design Methodology course 

11. Sustainability 

The sustainability of the Beach Cleaning Robot is integral to its design and purpose, addressing critical environmental, social, and economic challenges. This section elaborates on how the robot promotes sustainability across various dimensions 

11.1Environmental Sustainability 

1. Waste Reduction on Beaches: 
2. Beaches worldwide face severe pollution from plastic waste and cigarette filters as highlighted in the project statement. The robot directly contributes to cleaning this waste, thereby preserving natural habitats and preventing pollutants from entering marine ecosystems. 
3. By reducing waste, the robot mitigates risks to marine animals often harmed by ingesting or getting entangled in debris. 
4. The pieces of the robot, after his lifespan should be either repurposed or recycled, to ensure minimal impact on the environment. 

1. Renewable Energy Utilization: 
2. Designed to operate using renewable energy, such as solar power, the robot ensures minimal environmental impact during its operation. This aligns with reducing reliance on fossil fuels, combating climate change, and promoting green energy 
3. As developed a system of interchangeable batteries could also benefit to the robot, allowing to have less weight, and add versatility, to not only rely on solar energy 

1. Material Efficiency and Recycling: 
2. The robot incorporates sustainable materials like stainless steel for their strength and the need to sustain rude environmental conditions, and possible corrosion. However, further study on the impact of the surrounding and sand should be done to assess if more surface treatments are necessary. 

11.2 Social Sustainability 

1. Minimizing Human Labor: 
2. Beach cleaning is often labor-intensive and exposes workers to hazardous waste. By automating this process, the robot ensures worker safety and reduces the physical burden on humans. 
3. This technology allows local communities and volunteers to focus on awareness campaigns and preventive measures instead of cleanup efforts. 

1. Encouraging Environmental Awareness: 
2. The deployment of the robot serves as a visual representation of sustainable innovation, inspiring communities to value and participate in eco-friendly initiatives. This contributes to a cultural shift toward environmental responsibility. Therefore, implementing a more friendly appearance, reminding of the ecological impact would be beneficial (initial idea of turtle shaped robot). 

11.3 Economic Sustainability 

1. Cost-Effective Design: 
2. The robot's parts are selected according to cost-effectiveness and accessibility. For prototyping, a similar approach was conducted. For instance, employing PVC tubes for rollers and readily available conveyor belts reduces manufacturing expenses while maintaining performance. 
3. Modular elements, guarantee reduced maintenance expenses and extended usability over time. 
4. Energy Efficiency: 
5. The energy needs are calculated to achieve a balance between performance and energy use. For example in the prototype, the conveyor belt functions with an effective power of 1.5 W, whereas the motor power for movement is fine tuned to 5.5 W per motor. This leads to a very effective system with minimal operating expenses. Similar approach as to be caried out in the selection of motors and electrical components for the finished product. 

1. Enabling Scalable Solutions: 
2. The robot's autonomous design and capacity for prolonged operation make it ideal for use by governments, environmental groups, and event planners. Its affordability promotes extensive use, enhancing its beneficial environmental and social effects. 

11.4 Design Sustainability 

1. Durability and Longevity: 
2. The utilization of durable materials such aluminum and stainless steel, guarantees that the robot can withstand tough environments like sand abrasion and moisture, prolonging its lifespan. 
3. Ball bearings (e.g., SNR 608ZZ) are chosen to reduce mechanical losses and improve reliability. 
4. Adaptability and Upgradability: 
5. The modular structure enables future enhancements or substitutions of parts. For example, the picking mechanism could be replaced without impacting the rest of the rob functionality. 

11.5 Alignment with Global Goals 

The Beach Cleaning Robot aligns with global sustainability goals, such as: 

1. UN SDG 14 (Life Below Water): By removing pollutants from beaches, the robot actively protects marine life. 
2. UN SDG 12 (Responsible Consumption and Production): Its energy-efficient operation and use of recyclable materials promote sustainable production practices. 
3. UN SDG 13 (Climate Action): The emphasis on renewable energy reduces the robot's carbon footprint 

The bill of materials is listed here above.

Naoufal Bouchaara: I have a background in electromechanical engineering, having completed my bachelor's degree at ULB. For this project, I primarily worked on the digging system and the casing of the robot. My favorite part of the project was designing the digging system, as it allowed me to combine technical problem-solving with creativity to develop a functional and efficient mechanism.

Martin Dubus : I obtained my bachelor in engineering last year, in the ULB. Such as Naoufal, I worked on the digging system, and on his design, taking it from a theoretical concept, inspired by the stairs in fun fairs, to a concrete concept. I worked primarily on the modelisation, and on the analysis of pre existing concepts of beach cleaning robots. I also liked assembling circuits and mechanical parts of the robots.

Aaron Mahaudens: Former ULB Student. Actually student in master robotic and mechatronic at bruface (VUB/ULB) For the project, my sub team focused mainly on the waste collecting system with Naoufal et Martin. On my side I worked on the assembly part which is my favourite part. This is the moment when the prototype comes alive, the project was also a great learning opportunity on how to manage team work. Identity what has been correctly done and mainly the things to improve.

Shahid Hussain : I come from Kota, a city in the the state Rajasthan in India. I completed my Bachelor in mechanical Engineering in 2023 there. Then I decided to hone my skills practically, so I chose to pursue further eucation in VUB(ULB). I worked on the roadmp, and forward planning of this project. I worked actuation part of the moving mechanism, sensors, power and torque analysis, differential drive, lifecycle estimation.

Ali Sayyad : I am an international student and have completed my bachelor's degree in mechanical engineering from the University of Engineering and Technology Peshawar. For this project, I primarily worked on the moving part of the beach-cleaning robot. My tasks included designing and selecting the size of the wheel, ensuring optimal functionality, contributing to the sustainability of our project, and the design of the movement systems. I particularly enjoyed exploring and working with different technologies at the FabLab, many of which I had not used before. This experience allowed me to enhance my technical skills and creativity.

Gheorghe Bitlan : I am a former ULB student, in my spare tim i like to disassemble old devices, learn their mechanisms, and reuse their components. On this project I worked on the moving mechanism with Ali and Shahid, on the 3D model of this mechanism. I designed the electric circuit, dimensionned the motors, and pieces, wrote a part of the code, and on the manufacturing and assembly of the manual pieces. A special thanks to my parents for all their effort to find materials for the project such as the wheels, the metal sheets, and many others. I particularly enjoyed the electric circuit and the assembly in this project as it helped me to understand new concepts and push myself to design better pieces.

https://drive.google.com/drive/folders/1-iPvxDqnnrKTaTFXRBjQw6HB4XibrqkU?usp=sharing