Bipedal Robot Exoskeleton

A robotic exoskeleton is a mechanical device worn by a human being for certain purposes or applications. An exoskeleton is generally considered to be a hard mechanical frame with joints that allow movement of the human operator. There are other types of exoskeletons that are softer and are worn on the body, supported by the internal skeleton of the human being. Another classification is between motorized and passive exoskeletons. A motorized frame can use hydraulic, electric, pneumatic or any other type of actuator. A passive exoskeleton, on the other hand, does not have any type of motor, and serves to provide mechanical support to people when they are sitting or standing for long periods, or to assist movement by using a spring to store energy [1]. 

Robotic exoskeletons made for humans may look different depending on the functions they serve. Exoskeletons can be made of different materials such as carbon fiber, metal and elastic. Their coverage also varies from the entire body, to lower or upper extremities, or to a specific body part like the shoulder, hip, or ankle. Some exoskeletons have adjustable hardware, so they can be tailored to the individual that is using them [2].

The main objective of this instructable is to provide the proper steps for you to design and construct your own Bipedal robot.

The gait cycle describes the cyclic pattern of movement that occurs while walking. A single cycle of gait starts when the heel of one foot strikes the ground and ends when that same heel touches the ground again. The two main phases of gait include are the stance and the swing phases. The stance phase is the period of the gait cycle when the foot is on the ground and bearing body weight. More specifically, it can be described as the period between the moment that the heel of the foot touches the ground (heel strike) until the moment that the toe-off occurs. The swing phase is the second phase of the gait cycle when the foot is free to move forward. It is described as the period between toe-off and heel strike [3].

This Bipedal robot has the following specifications:

— Height: 30 cm

— Built with laser-cut MDF

This exoskeleton has the ability to:

— Replicate the gait cycle

— Walking the highest number of steps without falling during a certain period of time

— Walk a specific distance in the shortest period of time

References:

1. What are exoskeletons - Iberdrola - Iberdrola. (2023). Iberdrola. https://www.iberdrola.com/innovation/what-are-exoskeletons#:~:text=Exoskeletons%20are%20wearable%20structures%20that,or%20augment%20their%20physical%20capabilities.
2. SeedX. (2022, April 14). What Are Human Robotic Exoskeletons Made Of? - Ekso Bionics. Ekso Bionics. https://eksobionics.com/what-are-human-robotic-exoskeletons-made-of/
3. Phases of the Gait Cycle: Gait Analysis» ProtoKinetics. (2018, November 28). ProtoKinetics. https://www.protokinetics.com/understanding-phases-of-the-gait-cycle/#:~:text=Two%20Primary%20Phases%20of%20the,foot%20is%20in%20the%20air.

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Brenda Sofía Pastrana Monzón

Ximena Cisneros Rosete

Jesús Emilio Perea Morales

• Medium Density Fiberboard (MDF) 3mm
• Servomotors SG90V 9g Micro Servo
• Rolling Bearings 5x11x5 mm
• Couplings
• Laser cutting machine
• Inovamaker 3D printer
• Arduino

For this first step, you need to explode your imagination and creativity because it's the part in which you can change the main design proposed.

The design and drawing of the legs and Arduino's box was made in SolidWorks, but it also can be drawn in Catia. The measures are colocated there, but you can also download the pieces.

The parts required for this project had to be custom.

Note: From here on, the parts will be referred to using the names in the list.

• Base+caja+exo x1
• Base+pie x1
• Lateral+caja+exo x2
• Lateral+largo+caja+exo x2
• Pieza+con+hoyos x2
• Pieza+union+ servo x2

Here we added the pieces in order for you to modify them, but also the DXF document is colocated.

This step for you to make sure that the pieces assemble correctly, and that there are no errors.

Cut the pieces in the laser cutter and assembly them as the image shown.

There are two programs, because one recreates the gait cycle and the other makes the robot walk.

Now that you have everything, test if your robot walks and recreates the gait cycle.