Jung and Chung

Jung and Chung

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• Parameters of the Robot
• Systematic Errors
  • Unequal wheel diameters
  • Wheelbase uncertainty
  • Scaling error
• Initialization
• Procedure
• Calibration
  • Return position errors
  • Centers of gravity
  • Systematic errors estimations
  • Correction of the robot parameters

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: Jung and Chung assume that the scaling error was already corrected.

Initialization (up)

Procedure (up)

1. Measure the absolute position and orientation of the robot, and initialise the odometry system with that pose
2. Run the robot through a 2x2 m square in CW (clockwise) direction:
   • Stop after each 2 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
3. Upon return to the starting zone, measure the absolute position and orientation of the robot
4. Compare the absolute pose (e.g., using a tracking system) to the computed pose by odometry data
5. Repeat steps 1-4 for four more times (number of total runs: 5)
6. Repeat steps 1-5 in CCW (counter-clockwise) direction
7. Adjust the robot parameters

Calibration (up)

Return position errors (up)

Centers of gravity (up)

Systematic errors estimations (up)

• L: square side length
• αeb, αed: orientation error occurred after "on-the-spot" rotations due to wheelbase uncertainty and unequal wheels diameters
• βed: orientation error after straigh segments due to unequal wheels diameters
• R: radius of curvature (relative to an expected straight path)

Correction of the robot parameters (up)

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