Perfect 90 degree turn.

I have boe-bot that I am trying to get it to run a pattern I have laid out. It does the first few turns perfect but after that it turns to far. What do I do?


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  • There may be a bug in your program around the piece of code dealing with the last turn. On the other hand, servos are a bit "sloppy" and, despite the best of coding, they may not be accurate enough for a perfect pattern. In addition, wheels can slip and that will throw off your pattern. You can get wheel encoders for a boe-bot that will give feedback to a program about actual wheel position and that can be used to correct for the sloppiness of servos. Wheel slippage is harder and requires some method to sense actual (absolute) position. Sometimes just slowing down the boe-bot will reduce slippage or ramping the speed up and down or changing the floor material (using a mat in the area).
  • Getting a robot to drive in a repeatable manner is a tough challenge.

    There are a variety of techniques you could use to get better results. The "standard" way (if there is one) would be to use encoders. Encoders allow feedback from the wheels to make sure the wheel actually rotated as much as you intended them to rotate.

    Another way to improve the repeatability of your robot is to power the motors from a regulated power source. As the batteries on the robot drain, the voltage of the batteries drop. This reduced voltage makes the wheels turn slower. By using a regulator between the batteries and the motor, you can insure the motors receive a constant voltage supply.

    I discuss the trouble I had getting one of my robot to perform a figure 8 in this post. I wasn't able to get the robot to travel in a predicable way until I added a voltage regulator for the continuous rotation servos.

    Don't use the 5V regulator on the BOE to power the servos. I don't think the regulator on the BOE can supply enough current for the servos. You'll probably need to purchase a separate regulator. These regulators only cost a couple dollars so it's not a major expense.

    I described the regulator I used in the thread linked above.
  • Thanks but what I ment is that it is over turning instead of slipping.

    Thanks, RollTideKid11
  • over turn means going past 90%.
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