I’ve been reading up on position tracking algorithms for autonomous and programming skills, and the consensus seems to be that dedicated tracking wheels are far more accurate than integrated encoders due to wheel slippage. Many teams seem to be using 3 tracking wheels to account for robots strafing slightly while moving. However, with tracking wheels requiring an encoder each (taking up 2 ADI ports each!), it seems like a robot with three tracking wheels would be severely limited in terms of available ports.
Some teams also use ultrasonic sensors to “calibrate” their position tracking against a known object (such as the corner of the field). I could see this being a very useful strategy in Tower Takeover. However, it would be impossible to hook up 3 encoders and 2 ultrasonic sensors simultaneously due to the low number of ports, to say nothing of connecting additional potentiometers, limit switches, or other devices for other parts of the robot!
I figure I’ll need at least 1 potentiometer or limit switch for a lift, and probably one more for some other function (perhaps detecting if a cube is present?)
Which would you say is more important? A third tracking wheel or an ultrasonic sensor? Or should I just wait for the ADI expander to come out? (Although we all know VEX’s track record with these things…)
- Use 3 tracking wheels
- Use 2 tracking wheels and an ultrasonic sensor
- Use 1 tracking wheel and 2 ultrasonic sensors
- Switch back to v4/Cortex
- Wait for the ADI expander