At the beginning of this project, the project was outlined in a structure that involved two phases (each complete with a series of smaller tasks). Phase 1 involved a full overhaul of the Power Wheels vehicle so that it could support the weight of an adult human and drive at speeds that would be close enough to those of a real car that it could be considered a simulation of an actual vehicle. Phase 2 involved taking this overhauled vehicle and fitting it with enough sensors so that it could obtain autonomous vehicle capabilities.

When the original car arrived, we began by running a series of initial tests on it. After cleaning off the outer shell and the driver area, we tried to start the vehicle for the first time, but our attempts were unsuccessful. After checking various parts, we determined that the issue was in the battery. We found a similar, but slightly larger, battery and were able to fashion a connector that would allow us to use it with only one minor complication. As the battery was not made originally for the Power Wheels car, it was slightly too large to fit within the cut out area for the battery.

After we had a working vehicle, we decided to conduct baseline tests to determine its initial capabilities. We set up a track across the back of our lab space where we ran 12 hand-timed trials to determine the time it took us to travel a distance of 24 feet. Following simple calculations and unit conversions we determined our baseline speed was about 3.5 mph. From this initial number, we set what we believed was a reasonable goal for the maximum speed of our finished product: 10 mph.

Due to a lengthy approval process required by the school to order new materials, we experienced several delays in the arrival of our materials. While we were unable to begin the overhaul of the vehicle without new parts, we were lucky enough to already have our vehicle in our hands. We took advantage of this by using the time while we were waiting for our materials to come in to test a few different sensors that we knew we would need in the second phase of our project. Using some old ultrasonic sensors and a speaker we found in the lab, we fashioned a backup safety system for our vehicle. As obstacles neared, the speaker would start beeping while the volume and frequency of the beeps increased as the distance to the objects decreased. This technology would be incredibly useful in the final product as with a number of these sensors positioned around the vehicle it could “know” where objects were around it.

As our orders began to arrive, we were able to officially begin Phase 1 of our project. The first step of this process involved the construction of a new chassis to add stability to the structure of the vehicle and increase the load it could handle. We ordered bulk 80/20 aluminum for this purpose as it was relatively lightweight, durable, and easy to assemble. We used a bandsaw to cut down the long rods to the desired length and then tapped the holes on the end so that they could be used with screws for sturdy attachment. Following these preparatory steps, we assembled our chassis and attached a wooden slab to the bottom that would eventually hold the gearboxes, motors, and other electronics.

Attaching the original plastic shell to the chassis proved to be more difficult than expected. While the dimensions of the chassis were correct to fit the plastic shell, the original shell had a number of aesthetic and structural features that made it impossible to attach it to the new chassis immediately. As a result, we used a saw to cut down some of the excess material of the shell as well as some purely aesthetic features. Additionally, the original wheel and axles made it impossible to attach our new chassis so we removed those from the shell as well. Once this process was complete we were able to fit the original shell snugly on top of the new chassis. Although it was not yet permanently attached, this was an encouraging step. Next, we focused on reinforcing the plastic so that it can support the weight of a person. To do this, we took multiple wooden blocks and drilled them into both the frame we constructed and the plastic chassis. After doing so, the constructed frame and plastic are solid and provide good support.

Another item needing replacement from the original vehicle was the steering wheel. The original vehicle came with an extremely flexible and flimsy plastic steering wheel that was difficult to turn and impractical for our uses. In an effort to solve this problem, we designed a new steering wheel on an online CAD software called Onshape where we could easily multitask. After the design process was completed, we printed the wheel on a Lulzbot TAZ 6 3D printer and replaced the original wheel with our newly constructed one.

The next step was critical in making our vehicle suitable for an adult passenger. In the original car, there are two small plastic seats that were far too small for an elementary school student, let alone an average adult. We removed the original seating arrangement easily, but adding a new seat was more difficult than expected. We discovered that simply replacing these smaller seats with a new seat would not give the driver enough room to be comfortable so we cut off the back wall of the original shell, filled the empty space with a wooden slab, used pieces of wood to raise up the platform, and positioned our seat in a way that was farther back and raised up from its initial position. The addition of a new seating arrangement provided other benefits as well as we chose to use the new platform as a means to permanently attach the plastic shell to the chassis.

Following this point, we have experienced significant delays as the original gearbox we ordered ended up being out of stock. We have placed an order for a replacement gearbox, but as with all orders there is a significant delay between the time we order and the time the materials arrive. There has been a sort of domino effect that has had many implications for our project. Since we have not had gearboxes, we have been unable to attach motors or wheels. As a result, our vehicle is unable to move, and while we were able to complete some parts of Phase 2 without the capability of motion, we will be unable to progress until these materials have arrived. However, when the gearboxes do arrive, we plan on connecting two motors into each of the two front gearboxes to give our vehicle a front wheel drive.

Despite these setbacks, we have been able to take a few steps towards the goals set for Phase 2. One of the most significant of these steps was the addition of an IMU to the steering wheel. This will drastically increase the speed at which we are able to progress once the gearboxes have arrived as we will no longer have to worry about any complications that may come with mechanical steering and move forward with a far less complicated digital approach.