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The steering system was designed to be implemented in Trinity’s Formula SAE racecar. All design choices were made first with respect to the FSAE rules and then to the team’s production capabilities (manufacturing skill level and the limitations of Trinity’s machine shop equipment). The system was first evaluated by its compliance with FSAE rules: limited degrees of free play, quick release safety compliance, and the clearance of the cockpit template, front uprights, and wheel rims. The next feature that was evaluated was the car’s ability to navigate a hairpin turn. The steering system was evaluated by its toe in/out, steering ratio, and Ackermann percentage. At low speeds, Ackerman geometries improve the cornering ability in fast, technical tracks.
Test 1 evaluated the free play present in the steering system. FSAE mandates that there be no greater than 7 degrees of free play. The car successfully passed Test 1 revealing that on average there are only 5 degrees of free play in the steering system. Test 2 assessed the car’s ability to navigate both clockwise and counterclockwise hairpin turns by comparing the actual operating range with previously computed minimum inner and outer toe angles. The operating angles exceeded the minimum steering angles; therefore, the car should be able to navigate all turns in the Autocross and Skidpad events. Test 3 was designed to mimic the track at the annual FSAE competition. The powertrain subsystem remains incomplete, so the car is to be pushed by design team members while another member steers the vehicle. Due to a recent unexpected break in the left front A-arm of the suspension, Test 3 has not been performed. Test 4 assessed the function of the quick release, cockpit ergonomics, and the ability of a driver to safely exit the vehicle in 9 seconds. Thirty trials by three different drivers demonstrate the success of the quick release feature and the ability to exit the vehicle in far less than 9 seconds.
A primary objective of this senior design project was to meet FSAE guidelines and create a robust system that can be optimized by future senior design teams. Given that the steering system passed the 3 tests that were performed, it is clear that we have produced a working steering system that will provide a strong basis for the next team that continues to prepare the car for competition. Another objective was to produce the car while cognizant of the different FSAE events that the TUMS car will eventually compete in. Two other objectives were to follow a thorough design process for the steering system and to maintain records of design decisions, engineering drawings, and inventory for future students who will work on the car. Throughout the process the team kept organized notes on materials, vendors, purchases, and decisions. Two more objectives were to fabricate and assemble the steering system and implement a placeholder for the incomplete suspension system. Both objectives were met: the steering system is complete and two wooden blocks were placed next to the uprights to support the car in lieu of a function suspension system for testing.. A final primary objective was to dynamically test the steering system (Test 3), but this was not met. Several welds must be repaired before Test 3 can be safely performed. All welds on the suspension and powertrain should be evaluated and strengthened if needed before dynamic testing should proceed.
A secondary objective (not formally evaluated) was to manage the implementation of a braking system to be completed by the current TUMS members. All components of the braking system have been ordered and received. There is a plan for the assembly, but there were not as many active and available TUMS members as anticipated so it has not been completed. To achieve a fully-implemented braking system, all parts should be assembled and plumbing lines purchased and strategically attached. The final goal was to integrate and complete as much of the previously designed subsystems as possible (powertrain, suspension, electronics, etc.). Much research and many steps have been taken towards this objective, but there is a significant future work necessary to achieve a running powertrain and integrated, functional car.
Anderson, A.; Bentz, G.; Grusak, D.; Marques, J.; and Wilson, L., "Final Design Report: Design and Development of an Ackermann Steering Geometry for a Formula SAE Car" (2019). Engineering Senior Design Reports. 33.