Payload Pointing from Mobile Robots

Abstract

Payload tracking maintains alignment between a payload and a target while both payload and target may be moving. This research investigates the generic problem of tracking from a mobile robot. A tracking strategy based on subsystem interactions is developed along with tools to model and evaluate payload tracking, metrics for evaluating tracking configura-tions, and guidelines for developing configurations suitable for payload tracking from mobile robots. The strategy was implemented to design a communication system to achieve high bandwidth communication from a desert exploring mobile robot using active pointed high gain antennas . Tracking is important for many applications including high bandwidth communication enabled by pointing of high gain antennas and active camera vision. In the case of moderate speeds across rough terrain, tracking demands high slew rates and large motion ranges due to vehicle motion disturbances. This differs from satellite antenna tracking or telescope pointing where the need is for very high precision but incurred motion rates are small. Moreover, mobile robots are commonly mass and power limited. Attaining tracking stabil-ity requirements coupled with large articulation ranges, high slew rates, as well as low mass and power makes the problem of payload tracking from mobile robots challenging. This research considers the complete robot (mechanism, planning and control) to achieve precision tracking. This is important because an independent fine pointing device such as a gimbal alone- without cooperation from locomotion, suspension and isolation devices - might not provide the angular excursions and disturbance rejection needed in rough terrain. As the terrain roughness and corresponding excursions and disturbances increase, so does the need for robot subsystems to functionally cooperate to achieve payload tracking.