Control of off-road mobile robots using visual odometry and slip compensation

This manuscript evaluates through physical experiments a navigation architecture for off-road mobile robots. It has been implemented taking into account low-cost components and computational requirements while still being able to robustly address the required tasks. The visual odometry approach uses two consumer-grade cameras for estimating robot displacement and orientation (visual compass). One of these cameras is also used for slip estimation. The control scheme updates online the feedback gains taking into account the current slip. Furthermore, the setpoints are sent to two low-level controllers, PI controllers with anti-windup, properly tuned. In order to validate the proposed architecture we have employed a tracked mobile robot in off-road conditions, gravel terrains, with a slip around 5 [%]. The selected physical experiments show the right integration of the localization layer (visual odometry with visual compass) and the control layer with the slip compensation controller and the appropriate computation time (lesser than 0.2 [s] are employed at each sampling instant).