My portion for this week was largely surveying what RoboClub had and re-evaluating our design decisions.
One of the largest issues we were worried about was power consumption. Luckily, RoboClub has 3600 mAh 7.2V batteries available. Although this is for sure more than what we need, for extended testing purposes it is nice to have.
The next was our method of locomotion. There are a few beefy motors available to us. However, we would like to not be fully reliant on perfect hardware, as well as still trying to hit around our 100$ budget benchmark. Therefore, we will use HS-311 servos. While servos might seem like a good option, they do not allow continuous rotation at our budget. We therefore will move forward with basic 6V DC motors and an L293D H-bridge to control them.
The diagram below shows how our system will connect together (replace the servos with motors, and buck converter with H-bridge):
One worry I have with the current design is the fact we have so many pieces all on the same 5V line. I worry that they will brown each other out. However, we at least will have the servos motors separate, so that’s good. We may need to similarly separate the UWB from the ESP, but the math suggests we probably won’t.
The last issue we are still working through is our MCU. Initially, the ESP32-S3-WROOM-2-N32R16V DEV BRD seemed like a pretty clear choice as it satisfied all our processing and communication requirements. However, now that our system is a little larger and has more room for components, discussion about teleoperation has opened up again.
If we want that, the ESP32 does not have a built in camera port. This means we either need a separate camera part for this, or we need a different board. The ESP32-CAM 2MP WIFI+BT AI-THINKER or Freenove ESP32 CAM Dev Board Kit are the alternatives currently being considered, but the satisfaction of our system requirements is closer than we would like. We will likely order one to confirm it works, but as the camera / teleoperation with camera feed is more a stretch goal it is not the priority.
The rest of the parts besides our MCU are settled. We therefore can proceed with ordering, and I can proceed with starting housing designs for most of the parts!