Skills: Mechanical Design, SolidWorks Modeling, Basic Circuitry, Soldering

In my Spring 2020 semester at Rowan University, three mechanical engineering students and I were tasked with designing and fabricating a miniature solar powered vehicle as part of our Introduction to Renewable Energy course. Unfortunately, due to the Covid-19 pandemic, the project was cancelled. However, I continued forth with the project on my own because I was eager to take on a fun environmental engineering project! My old teammate gave me the DC motor to mobilize the solar car and I got to start on designing the car. The criteria and constraints of the project were as follows:

Use one or two Velleman solar cells(2V/200 mA) as the main energy source.

Use a JAMECO No. 2158442 DC motor requiring 0.17 A current for max efficiency.

The dimensions of the prototype cannot exceed 8" x 6" x 6".

The weight of the prototype cannot exceed 2 lb.

The cost of the system cannot exceed $30; not including cost of provided DC motor.

Secondary, backup energy sources limited to supercapacitors, capacitors, or batteries. These cannot contribute to more than 20% of the energy during the race.

Planning It Out

The class goal for the solar car was to achieve the fastest race time on a 30 foot racetrack. So with speed still in mind, I decided to make my solar car using 1.5 mm balsa wood sheets as my main material due to its light weight and high strength. To drive the car, I opted for a simple gear mechanism consisting of a gear on the DC motor and a crown gear on the back axle with a 1:2 gear ratio. I also drew a rough sketch of what I wanted the car to look like before modeling it in SolidWorks.

SolidWorks Modeling and Assembly

Modeling the parts in SolidWorks was straightforward. I started by modeling the parts I already had in hand including the solar panels, stepper motor, axles, gears, and wheels. Afterwards, going off the rough sketch I had in mind, I started with a 5.5" long chassis and then built the rest of the car body around it. Each component was designed to fit into a slot in the chassis for easy assembly.

Building the Car

Once I was satisfied with my SolidWorks Assembly of the car, all that was left was to cut the design out on the balsa wood sheets! Since COVID-19 cut off my access to my university's laser cutter, I resolved to cut out the sheets by hand by tracing my component patterns onto the wood sheets. With all my cut out components in hand, I inserted their end tabs into their respective slots and secured their placement with glue. I soldered the stepper motor to the solar panels and wired the panels in series. I secured my soldering work with heat shrink as well. After putting the gears onto the motor and back axle and attaching the wheels my car was completed! Overall, this was a fun and simple project that I was happy to finish.