Correction of systematic odometry errors in mobile robots

2. Properties of Odometry Errors This paper describes a practical method for reducing In a typical differential drive mobile robot incremental odometry errors caused by kinematic imperfections of a mobile encoders are mounted onto the two drive motors to count the robot. These errors, here referred to as "systematic" errors, stay wheel revolutions. After a short sampling interval I the left and almost constant over prolonged periods of time. Performing an right wheel encoders show a pulse increment of N and N , occasional calibration as described here will increase the respectively. Now, suppose that robot's odometric accuracy and reduce operation cost because an accurate mobile robot requires fewer absolute positioning c = %D /nC (1) updates. Many manufacturers or end-users calibrate their robots — usually in a time-consuming and non-systematic trial where and error approach. By contrast, our method is systematic, c Conversion factor that translates encoder pulses into provides near-optimal results, and can be performed easily and linear wheel displacement. without complicated equipment. D Nominal wheel diameter (in mm). Experimental results are presented that show a consistent C Encoder resolution (in pulses per revolution). improvement of at least one order of magnitude in odometric n Gear ratio of the reduction gear between the motor and accuracy (with respect to systematic errors) for a mobile robot the drive wheel. calibrated with the procedure described in this paper.