Motor speed calibration firmware 8

This is an old page refering to version 8 of the firmware, see updated method on: thymiomotorcalibration

The Thymio robot may not travel in a straight line when you set both motors to the same power level. This is because no two motors are exactly the same, so the same power level may result in different speeds of the motors. This page explains how to calibrate the motors on your robot so that it will travel straight.

The calibration is supported starting from firmware V.8. If you have an earlier version, see this page for instructions on upgrading your robot.

Print this pdf file and tape it to a table or the ground. (Print the file on A4 paper at 100% twice and tape them together; alternatively, print once on A3 paper.) Place the robot between the lines and run the predefined obedient (purple) mode, which enables you to control the forward speed of the robot. If the robot remains between the lines for 40cm, calibration is not needed; otherwise, carry out the following procedure:

  • Open Aseba Studio and open this source code file (or extract the file from this zip file).
  • The Front and Back buttons make the robot move forward and backward. Press them once or twice to modify its speed, so that you can check if the robot travels straight at different speeds.
  • The Left and Right buttons increase or decrease the correction in the direction of travel: If the robot turns right, touch the left button to correct the direction until it goes straight, and conversely.
  • When the robot goes straight, touch the central button. This will stop the motors and record ("flash") the correction value into the robot.
  • Power off the robot.
  • Power on the robot again and check the results of the calibration by running the predefined obedient (purple) mode.

Here is a video showing a calibration example:

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