College of Engineering
Mechanical Engineering Department
BS in Mechanical Engineering
The following document outlines the design process, manufacturing, and testing of the control system for an electronically controlled continuously variable transmission (ECVT). This control system was integrated into the custom designed and manufactured mechanical transmission system created in parallel by another senior project group. The transmission was designed for use in the Cal Poly Baja SAE vehicle. Through researching customer needs, competition requirements, previous and alternate CVT designs, and vehicle characteristics, we were able to determine the requirements and specifications for our unique system. Input, output, speed, and durability requirements guided our hardware selection. The primary components which comprised our system include an alternator and regulator, a custom circuit board, rotary encoders and hall effect sensors, brushed DC motors, lead screws, and a custom system enclosure; further details are included in the Final Design section of this report. With the knowledge of our vehicle characteristics, actuation mode, and inputs, a system model determined that a standard proportional + integral action (PI) controller would be sufficient to obtain the speed and accuracy demanded by our customer needs. Electrical components were assembled, tested, and programmed on a prototyping breadboard, and a custom printed circuit board (PCB) was outsourced for manufacture following qualification of our prototype. The final production board was bench tested with the mechanical CVT system to ensure it met all customer and design requirements. Furthermore, the enclosure was tested to ensure the safety and durability of the electrical systems. Planning and timing mismanagement between our team, the mechanical design team, and Cal Poly SAE Baja team, in conjunction with controls specific setbacks, resulted in the final combined system remaining untested on the Baja vehicle. This project is being continued by a new senior project group which will continue to test and improve upon the current system during the 2019-2020 academic year.