Construction
The RC Baja vehicle was built in two different sections. This being the front and rear suspension systems with the steering system tied in with the front suspension as it is mounted on the front carriage. With that being said, the coils and shocks that go into the front and rear and the servo which controls the steering mechanism were purchased rather than modelled as well as the turnbuckle rods for steering and wheels. The upper and lower control arms for the front and rear suspension were manufactured by the engineering team as well as the subframes and housing for the servo. The suspension systems inherently have far more components than the steering system as they needed more parts to make them functional and they perform more operations for the vehicle. To elaborate, the purpose of the steering system is to make the vehicle move right and left whereas the suspension systems are designed to control the vehicles movement and stability when encountering environments features and forces. The vehicle will utilize a double-wishbone suspension for the front and rear suspension systems. However, only the front suspension system required the servo and turnbuckle rods. The primary difference between the two beyond the front housing the steering system is the knuckle shape which as a result also required different shapes for the control arms.
Figure 3.1: Drawing Tree for Vehicle
Methods
The project was aimed to use a variety of methods to produce the parts needed for the vehicle however a number of choices had to be made that restricted this option. This primarily being that the entire vehicle was redesigned and was constantly changing over the course of the quarter. As a result, the only method of constructing was through 3D printing. This was done by taking a SolidWorks part and converting it into an STL file, this file was then sent to a printing application that would slice the part into layers and put support structures for complex geometry where it would be placed onto an SD card. After this, it would be plugged into the printer and the program would be run which results in a fully printed part that just needs to be deburred and have its supports taken out.
After this printer has completed its print it spits out parts like these. These parts have been deburred and had their structures removed making this the completed product.
This is the software used to prepare parts for printing. The parts must be positioned on the board and variables such as print speed and layer height must be specified before printing.
This is a completed version of the Rear Carriage with the Control Arms and Shocks installed. The Shock Tower was built into the carriage to minimize parts and accommodate the frame runners and chassis.
To the right is a fully complete steering system with the Servo Holder, Servo, Servo Arms, and Turnbuckle rods. This system went through multiple iterations to find its best fit for the project.
Cementing the idea of iterative design, what is seen here is three versions of the Servo Holder. The first version did not consider that the servo had to go inside of the mount. The second version was nearly right however the screw holes ended up being too large, the servo hole was slightly small, and the sleeve for the carriage was slightly small too. The final design corrected these items.
The final product resulted in the RC Baja Vehicle seen above. Both the Steering and Suspension and Drivetrain and Chassis engineering teams put their subassemblies together to create this final product that performs the basic operations of an RC car.
What is seen above is the printer fabricating the subframes that were used in the final assembly of the project. When the Creality program has generated the printing process needed for the part this program is run on the printer to emulate the rhythmic printing pattern that is seen on the above videos which showcase a top and side view of said process.
Above is the near full assembly of the rear suspension system used on the RC Baja Vehicle. After all fasteners are attached the range of motion is slightly demonstrated where the coils allow the arms to move up and then smoothly return to their original position.