Internal Correction of Odometry Errors with the Omnimate

This paper presents experimental results of odometric accuracy tests obtained from the first production model of an innovative mobile robot called “OmniMate.” The OmniMate is an omnidirectional platform that comprises two individually controllable drive units (called “trucks”) that are physically connected by a compliant linkage. The compliant linkage allows relative motion between the two trucks, thereby allowing momentary velocity discrepancies between the two trucks, which would result in wheel slippage if the trucks were linked rigidly. A linear encoder measures the momentary relative distance between the two trucks, and two rotary encoders measure the relative angle between the two trucks and the compliant linkage. Data from these three so-called “internal” encoders, combined with the data from the four wheel encoders in the system, allow for the implementation of a unique odometry error correction method developed earlier at the University of Michigan. Experimental results presented in this paper show that the OmniMate is likely the mobile platform with the most accurate odometry-based positioning system demonstrated to date.