Wireless Timing Gates
These wireless timing gates were designed to facilitate testing and data acquisition for my Baja SAE team. This version could be more easily deployed than their predecessors and allowed more data to be captured including sector times and instantaneous speed. They use the same contact sensor design the team previously developed, but I made the circuit and wrote the code to make the recording of data wireless instead of running hundreds of feet of wire. I also managed a small team of underclassmen who designed the mechanical components including the revised contact sensor and the housing for the PCB.
3D model of timing gate transmitter board
The demand for these gates arose because of a rule change for the Baja SAE competition. A key component to our car’s drive train is a custom mechanical continuously variable transmission (CVT). This is a belt clutch which shifts gear ratio of the drivetrain depending on the engine rpm. The idea is to stay on the torque curve so that the engine spins the wheels as fast as possible while producing the sufficient torque to move forward without stalling the engine.
While the process of tuning a CVT is a fascinating challenge, my task was to develop a system to allow our drivetrain subteam to collect data to experiment with different CVT tunes. I chose to use the same steel contact design for the gates the team used previously because that method of detection has been reliable and practical for the team in the past. I focused on the issues that were arising with the plan to use the old gates.
The old gates required length of wire to be run between them. This contributed to a long setup time and restricted the distances we could test at. I chose to go with a wireless setup which used ESP32 wireless microcontrollers to detect the car going over a timing gate, and then sends the information to another ESP32 mounted to the car which is responsible for timing and other data processing.
This wireless setup also affords other advantages and features. Without having to worry about wires, setting up sector timing is more practical. The gates have modes for point-to-point timing, circuit timing, and sector timing. This opens up functionality for testing suspension setups in different terrain (bumpy versus tight corners). It also allows us to measure timing in smaller intervals of acceleration for CVT tuning.
I also took advantage of the faster clocks on an ESP32 versus an Arduino to time in between the front and rear wheels hitting the gate. Using the known wheelbase, this method can accurately time the
For the best understanding of the functionality of this project, check out the GitHub project. I wrote all the code and the docs so that my team can continue to take advantage of the gates after I graduate.