23rd RoboCon R1 Vehicle Circuit Design

1. Main Control Board Stack-Up Design:
Our R1 vehicle has a total of 16 motors, 2 DT35 controllers, 1 MID-360 controller, 4 solenoid valves, and various PCB modules. To effectively utilize space, we adopted an integrated stack-up design for the main control board, voltage divider, and CAN bus, as shown below:
We divided the control into two main control units based on the upper and lower layers. This improved our code debugging efficiency; in terms of circuit design, we completely separated the circuits for different mechanisms, which helped us with troubleshooting during the competition.
2. CAN Cable Details:
During our school debugging, we encountered CAN crosstalk issues, which may have been related to the overly dense power and CAN wiring. We finally solved the problem by switching to industrial 485 shielded twisted-pair cables. We carefully stripped the outer adhesive and shielding layer of the 485 twisted-pair cable, soldered the XH2.54 interface wire to the internal battery, and then further twisted the interface wire.
In the wiring, we also tried to separate the CAN wire and power wire as much as possible.
3. Reverse polarity protection, short circuit protection, and electrostatic discharge protection:
Fuse sockets were soldered and fuses were installed on each voltage divider board. A low-side reverse polarity protection circuit built with NMOS was also used. In circuits with many motors, we typically solder several capacitors onto the voltage divider board to ensure relatively stable bus voltage. At the main control interface, we also connected a TVS diode and an RC snubber circuit in parallel.
4. Summary:
The hardware group is a very detail-oriented group. For our hardware group, the biggest task is to ensure the circuit design is sufficiently stable. Seemingly simple layout and wiring actually involve many details. Through practice, we found that the short-circuit protection response speed of fuses is often not as fast as expected. To prevent hardware damage during debugging, we are also verifying an overcurrent protection module with a faster response speed.