Real World Problems
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For our models, we assume the robot drives in a perfect world where we can measure exactly how far the robot moved.
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In time, the odometry drifts away from the real robot position due to errors incrementally adding up at every time step → the error is unbounded!
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A source of errors is the integration of velocity measurements over time to give position estimates (velocity is assumed to be constant for the time interval ∆t).
Problems that can occur in wheel odometry:
- Incorrect wheel size (e.g. wheel compaction).
- Wheel slippage on icy or wet surfaces.
- Losing contact to the ground. I Encoder inaccuracies (e.g. low resolution).
Odometry can be hard to obtain in different environments:
- Wind/water currents move flying/diving robots.
- More difficult to calculate on walking robots (forward kinematics).