Stepper motor controlled brake force distribution for a Formula Student race car

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Dr. Stumpf Péter Pál
Department of Automation and Applied Informatics


The topic of my final project is the complete hardware design of the Pedal box electronic control unit (ECU) for BME Formula Racing Team’s (FRT) 2015 race car. The task can be divided into three main parts. First, the unit should take care of the sensors around the Pedal box. Secondly, it should perform the brake system related functions for the shutdown circuit (SC). Furthermore, it should control two stepper motors which set the brake force distribution, thereby replacing the mechanical solution used so far, eliminating its weaknesses and disadvantages. The main design aspects are short development cycle and manufacturability.

For the implementation I used the top-down approach. After examining the relevant parts of the brake system, I chose a stepper motor and further hardware. This was followed by the printed circuit board design.

As a result of the design, the Pedal box ECU became part of the distributed electrical system to be placed in the car. It communicates with the other units via CAN (Controller Area Network) bus. It processes the signals of sensors placed around the Pedal box, such as throttle and brake pedal position sensors, brake pressure sensors, various temperature sensors, as well as wheel position sensors and wheel travel sensors and transmits them via CAN. Moreover, it monitors the operation of the brake pedal and transmits signals of its state for the shutdown circuit. One stepper motor drives the balance bar, adjusting the brake balance on the front and rear axle. The system plan includes the capability of adjusting the proportioning valve with the second stepper motor.

The technical documentation is complemented by a cost analysis. Based on my design, the printed circuit board is going to be produced by BME FRT and will be installed in an electric Formula Student race car.


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