Linear estimation of the physical odometric parameters for differential-drive mobile robots

In this paper a calibration technique aimed at identifying the odometric parameters of differential-drive mobile robots is proposed. The algorithm is based on two successive least-squares estimations based on the continuous-time kinematic equations of motion; the time-discretization error, thus, is avoided. The use of the least-squares technique is made possible by working on a linear mapping between the unknowns and the measurements and is not the result of a linearization. Another advantage of the proposed technique is that no specific path is required. The basic technique makes use of video-camera measurements and absolute position readings of the wheels' encoders; the use of different sensors and measurements of the wheels velocities is also discussed. Experimental results with a mobile robot Khepera II confirm the effectiveness of the proposed technique.