Baja Buggy: Steering and Suspension
Intro:
Central Washington University Seniors in the mechanical engineering and technology program were tasked with designing and manufacturing a fully functional RC Baja car. Two separate students teamed up and have divided the work between steering/suspension, and drivetrain/chassis, the chosen sector of work that is completed by the engineer Chayce Williams in this report is steering and suspension. Chayce Williams and his teammate Caden Harris competed against other teams of two in the drag race, slalom race, and Baja race, whoever has completed the challenges with the fastest time and most points wins the competition.
The rules are that each of the students were required to design and manufacture the entire RC car other than the motor, shocks, tires/wheels, battery, ESC, and servos. Because of this, to keep the competition fair, there is a supplied American Society of Mechanical Engineers Baja Buggy rulebook that has a long list of rules and requirements that students had to abide by. Knowing that there was a standard that students had to meet, engineering merit had to be applied to the engineering problems that had risen. Methods such as mechanics of materials, statics, dynamics, physics, SolidWorks (3D modeling), project management, planning, design, and rapid prototyping and even more have all been applied to each individual part that has been designed. The results of the engineering merit in this senior capstone is a fully functional remote control Baja car at a smaller scale with very close similarities to full scale trophy trucks, Baja buggy’s, and even side by sides.
Engineering Report
Videos
Fall: Design Stages
Winter: Manufacturing Stages
Concept Hand Drawings
Figure 1. Initial overall design
of suspension components and
overall side view look.
Figure 2. Top view of alternate design 1, independent suspension design front/rear.
Figure 3. Alternate design 2, front independent suspension, and rear solid axle.
Figure 9. Assembly Drawing
Results:
Steering and suspension is one of the most vital systems of an RC car for it to perform well in conjunction with the drivetrain and chassis developed by Caden Harris. The cars overall steering system took awhile to dial in and get right so that the car could be controlled at higher speeds. Some minor modifications/revisions had to be done so that it could perform the way that it was intended to. As well as the suspension system in the rear, spring rates, shock stroke lengths, and geometry were all variables the engineer had to either modify slightly, or ensure no failure was possible. At the end of winter quarter the RC car was operational, but not to the engineers standards. So revisions were made, and by the end of the spring quarter and all testing was done, the car performed very closely to how the engineers imagined at the beginning of the quarter when brainstorming ideas.
It was not an easy task, but it was possible, and the engineers Chayce Williams and Caden Harris revised, edited, and manufactured an RC car that is overall extremely fun, reliable, and competitive. And because of this, the engineers firmly stand by that this RC Baja car was a success.
Figure 23: Deflection Vs. Displacement Graph of Rear Trailing arm Test
Much of the RC car was far stronger than it realistically needed to be. It was the engineers goal to produce an extremely strong, and durable RC Baja basher car. In figure 22, the strength of the rear trailing arm component is exemplified. This was the same standard for strength that is held for the entire car. This rear trailing arm was able to withstand 400 lb and only deflect roughly 0.045". This same standard for strength was held for both the rear and front suspension components, and the steering. And because of this the cars overall performance on rough terrain, and abuse, the car is able to perform and be used the way it was intended to with no worries.
Figure 24: Finished RC Baja Vehicle
It is important to note that with this finished RC car that the engineers were able to compete in the RC Baja Slalom, Drag, and Baja race and finish first in the Baja, and finish first overall in the entire competition. There were zero broken parts, zero major malfunctions, zero failures of any kind during the competition and the engineers were able to do several laps around the Baja course and still be able to drive the car after the competition was over with.