UMBmark
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Parameters of the Robot (up)
- Di: diameter of the wheels
- b: distance between the right and left wheels
- n: reduction ratio ([n:1]) of the transmission coupled with each motor of the wheels
- Ce: resolution (ppr) of the encoder coupled with each motor of the wheels
Systematic Errors (up)
Unequal wheel diameters (up)
Wheelbase uncertainty (up)
Scaling error (up)
Note: the UMBmark method assumes that the scaling error was already corrected.
Initialization (up)
Procedure (up)
- Measure the absolute position of the robot and initialise the odometry system with that position
- Run the robot through a 4x4 m square in CW (clockwise) direction:
- Stop after each 4 m straight segment
- Make a total of four 90º "on-the-spot" rotations (includes the final rotation at the starting zone)
- Run the vehicle slowly and adjust wheels acceleration to avoid slippage
- Upon return to the starting zone, measure the absolute position of the robot
- Compare the absolute position (e.g., using a tracking system) to the computed position by odometry data
- Repeat steps 1-4 for four more times (number of total runs: 5)
- Repeat steps 1-5 in CCW (counter-clockwise) direction
- Adjust the robot parameters
Calibration (up)
Return position errors (up)
Centers of gravity (up)
Systematic errors estimations (up)
- L: square side length
- β: orientation error associated with unequal wheels diameters
- R: radius of curvature (relative to an expected straight path)
- α: orientation error associated with wheelbase uncertainty
Note: the article does not defines if the wheelbase used for computing Ed is the nominal (initial estimation) or the calibrated wheelbase. Therefore, the method's implementation developed for the project considers the calibrated wheelbase.
Correction of the robot parameters (up)
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