E-bump

Hello, if you are like me, a keen environmentalist, then this project could be for you. It has the aim of making a scaled down model of a possible solution to decreasing reliance on fossil fuels. It is a project that involves physics theory (Faraday’s Law of Electromagnetic Induction), woodworking, electric skills, combined with online software skills (fusion 360, v3 design etc.). Whilst there are some renewable means of generating electricity I believe we are still too heavily reliant on fossil fuels and I would like to help change that.

My design features a rotating speed bump that converts vehicle motion into electricity as it spins when vehicles drive over it. It could be used in areas where power cuts may be common so that it can contribute to emergency power supplies. It involves non-renewable energy use (cars, vans, etc.) generating renewable energy whilst reinforcing road safety infrastructure (speed bumps slowing down dangerous traffic in residential areas). 

The objective of this design is to create an environmentally friendly and sustainable solution for generating electricity from the movement of vehicles passing over a speed bump. I made a design that can be easily integrated into the existing infrastructure, whilst being safe and requiring minimal maintenance. The speed bump could be compatible with all types of vehicles: cars, vans, bikes, and more. My design will reduce noise pollution in residential areas, whilst providing a reliable source of green energy. Functionality is the priority, however, I also considered the aesthetics as it should blend in to avoid being visually intrusive.

The rubber is optional. You will need access to fusion 360 and a laser cutter. Additionally, you will need 3 chunks of 130x70x45mm wood and some plywood offcuts ( size depending on how large you want your model road to be - mine were 2 400x200 rectangles).

Before arriving at my final idea, I did extensive secondary research until I formulated an idea. From there I then iterated the design in fusion 360 and by sketching some quick models.

Attached are some materials I have prepared to help you complete this project. In this design I have decided to make a generator from home in order to create electricity from the rotary motion. In order to do this, I need 2 neodymium magnets and 10 meters of copper coil, as according to Faraday’s Law of Electromagnetic Induction, a fundamental principle in physics, a change in magnetic flux through a conductor induces an electromotive force (EMF). In such a device, an EMF is generated by rotating a coil within a magnetic field or vice versa. If the circuit is closed, this induced EMF results in an electric current. The efficiency of this process can be enhanced in two ways: by increasing the strength of the magnets and by increasing the number of turns in the copper coil. Both of these modifications serve to increase the output generated, making the generator more effective. Basically, when the magnets spin on the axle, the coil intersects the magnetic field lines which induces a current in the copper coil which can be soldered to an appliance such a light to power it. Hopefully the fusion 360 model attached will help you build it (measurements etc.).

First, I cut 4 pieces of wood to size (550x100x100mm) using a circular saw. The wood with the least knots is the best to use. Using PVA glue, stick the 4 pieces together and use multiple clamps overnight to ensure it a tight seal.

Draw two diagonals lines from each corner intersecting the middle. Do it on both ends. Draw a circle using a compass (this is the how large the speedbump will be).

Using the band saw at an angle of 45 degrees cut the 4 corners off to leave it as an octagonal prism. For safety, wear safety goggles and use a chisel to push the wood into the blade. The cross should still be visible as it is essential for using the wood turning lathe later on.

Next, secure the wood between the headstock and the tailstock of the lathe, make sure it is exactly in the centre on both ends.

Put on your safety visor and turn on the wood turning lathe and set the speed. Use a roughing gouge to round the wood into a basic cylindrical shape. Make sure you cover the whole wood evenly and just skim the wood so that you don't channel too deep into certain areas. Do it slowly back and forth and if it is catching keep the roughing gouge as straight as possible.

I used a pencil to draw a line marking where to cut on both ends. This is where the ends of the speed bump will be.

From here I gouged into the cylinder along the pencil line until a clear gap can be seen. Use it vertically for a thin bore.

Then, you can sand the cylinder using 3 different types of sandpaper, getting progressively smoother. I used 240, 150, and 80 grit for the smoothest finish.

With the wood still on the wood turning lathe, I sawed it off at each end in the gouges I made earlier. Keep your safety goggles on and fingers away from the blade for safety. You should be left with a smooth wood cylinder, but on each end with some wood sticking out that must be sanded down.

In order to sand the ends down for a smooth finish, I used the belt sander for efficiency and a completely flat end. I wore safety goggles for protection and turned on the extraction. I sanded both ends until they were smooth and flat. For the finish, I sanded the whole thing down by hand with p240 sandpaper so that the wood was as smooth as possible. 

Then, I drilled a hole exactly in the middle of both ends to a size that my ¼ inch axle will fit into. It is best to make the hole too small to start with then make it bigger to ensure the hole isn't too wide and the axle doesn't slip out. I wore safety goggles and made sure it was tightly clamped at a 90 degree angle. Clamp it in a wood vice not a metal vice to avoid damaging the wood. 

Next, I cut 2 axles (¼ inch diagonal) with a hacksaw and filed the ends. Wear safety goggles and keep your hand a safe distance from the saw and file. My original axle was slightly bent so I used metal clamps to straighten it.

Then, I tightly wrapped my 10m copper coil around the wood for a circular shape, minimizing overlap as much as possible. I then slid it off the side of the wood and zip tied the coil together for a ring shape. On either end of the coil I then soldered the correct poles of a red LED light whilst wearing safety goggles and keeping my hands away from the heat.

I then designed 2 holders for the copper coil of the generator using V3 design. The hole for the axle was circular so that it can spin freely without the coil rotating. I then put 4 holes around the center to fit M6 screws. I exported it as a .DXF file onto a USB stick. To check my design worked without wasting expensive materials, I laser cut my design on to card. I discovered that the 4 holes were too close to the center for the coil to sit on them so adapted the design, did 1 test run and then laser cut it onto green 3mm acrylic. I placed a neodymium magnet eithers side of the axle. Then, I used M6 screws and nuts to secure the holders either side of the 2 magnets and places the ring of copper coil over the screws where it sits.

Next, I used a wood plank to make a stand for my bearing. The sizing of the wood is not strict. I used a circular drill attachment called a hole saw to make a hole for my bearing. However, this only creates the outline of a hole so I had to use a spade drill attachment to remove the bulk of the hole. I used safety goggles and securely clamped the wood. The hole you drill must be the correct size for your bearing. The bearing must be a complementary shape for the axle.

Now I cut 2 cuboids of this wood to size and repeated drilling the hole into the second. I used a set square to mark where to cut and used the first as a template for the second so that the two sides were identical. The issue I ran into was when the bearing was put into the hole it squished the casing and so the space between the cogs compressed so the gears where grinding. To counteract this I sanded the hole until the bearing was a better fit. The height above the ground of the bearing is how high above the ground you want the speedbump to rest.

I used a hand-held sanding machine to create a smooth surface on each end of the wood. Then I sanded it by hand for the best possible finish. 

At this point I slotted in the axle and speedbump to test out the angle. I discovered that the axles were bending down a little bit under the weight so I used a hammer to knock both axles further in and after that it was much more secure. I used a small spirit level to check if the axles were straight and the speed bump was perfectly straight.

Finally, I built a model road to be as accurate to a full model as possible. I cut 2 thin 400x200mm rectangles of plywood using a hacksaw. The plywood was old and slightly damaged on the sides but since it is of a road (which are usually in bad condition anyway) it worked well.

I cut 4 planks of wood to 130x70x45mm. I then used the belt sander in order to make a smooth surface. However, I was not satisfied by the height of the speed bump above the road so I further sanded the wood planks equally so that the road was lower. The speed bump is now around 1 or 2 cm raised above the road which I believe is a good balance between effectiveness and safety.

Next I used wood glue to glue 2 of these planks to the bottom of each piece of plywood to act as a stand for the road. The planks were roughly centred and the same distance from opposite ends resulting in a stable and straight road surface. 

In order to confirm that the roads were straight I once more used the spirit level and once more it was shown to be almost perfect.

For the finishing touches of the project I painted the road black with white indicative symbols. To start with I painted the top and the sides of the plywood black. After painting it once, I wasn’t satisfied as some areas of the wood you could still see the original color. That’s why I did a second coat after which it looked just as I wanted. For the best results sand and lightly clean the wood before hand, then use wood paint.

The white road symbols are traditional to classic speed bumps. They are white triangles pointing the direction cars go over it. I kept them as they are simple and informative for drivers. I drew out the 3 triangles using a ruler, pencil, and compass. Then I firmly stuck down masking tape along the edges of the triangles to act as a template. I painted white over them them, waited for the paint to dry, and then peeled off the masking tape.

Finally, I assembled the pieces together and the build was complete.

In my user testing, I begun by testing it with a remote control car. In testing we discovered that the height of the speed bump from the road was perfect, as the front of the R.C car ramped up it without being damaged but clearly would have to slow down as a precaution. As shown in the images, I attached a camera to the R.C car which shows an angle of the wheel hitting the speed bump and traversing across it, as shown in the videos. I achieved this by using my ESP32 camera module in which code on the Arduino IDE app connects the ESP32 to your Wi-Fi and creates an IP address containing the software to view the camera and customize the image (apologies for the bad video quality it was the best I could do). The videos clearly show the front wheels hit the speed bump and continue over it. However, due to the fact that the weight of the R.C car is not proportional to that of a real car, there was not enough force to rotate the speed bump on it’s axle. However, in another type of testing, the R.C cars wheels rotate the speed bumps which proves the potential is there. The 2 bearings and their wooden stands also performed well under weight, with close to zero bending. The project is a very good setup for the future of this innovative idea, but there are improvements to be made...

The two updated fusion 360 designs attached show a steel speedbump as opposed to the wooden one (better durability, withstanding weather etc.) and the generator being incased for safety. On the other hand, the road markings are a good start but since there are significant changes to almost every aspect of the design and this means that in order to properly inform drivers of the new design, unique and special road markings should be implemented as the interaction between cars and the surface are very different in my product than with the original. There are a large number of extra changes that could be made to perfect the design (such as adding a rubber shell for grip) and I look forward to addressing issues to improve my model.