Boundary tracking by a wheeled robot with rigidly mounted sensors

We consider the problem of reactively navigating an unmanned vehicle along an obstacle in the case where data about its boundary are limited to the distance along and the reflection angle of the ray perpendicular to the vehicle centerline. Such situation holds if e.g., the measurements are supplied by several range sensors rigidly mounted at nearly right angles. A sliding mode control law is proposed that drives the vehicle at a pre-specified distance from the boundary and maintains this distance afterwards. This is achieved without estimation of the boundary curvature and holds for obstacles with both convexities and concavities. Mathematically rigorous analysis of the proposed control law is provided, including explicit account for the global geometry of the obstacle. Computer simulations and experiments with real wheeled robots confirm the applicability and performance of the proposed guidance approach.