We propose to develop a model-based control framework for wheeled mobile robots that robustly actuates a mechatronic robot drive with several steered wheels. Basis for our controller is a drive model that details the geometric wheel alignement and the dynamic behavior of the wheel's steering and angular-speed actuation for the operational and some fault conditions. Our proposed control framework uses this model to solve two major tasks through on-line reasoning methods that build upon theoretical kinematics, systems-analysis, filtering- and diagnosis techniques, and control-theory. The first task provides the current mode of operation or failure for every individual wheel through state-estimation based on measurements and model-predictions for possible mode evolutions. The second task uses the estimated mode of operation or failure, derives the kinematic constraints for this mode and deduces the coordinated actuation for the rotational speed and steering angle for each individual wheel to obtain the desired movement of the mobile robot. This on-line utilization of the robot drive's model enables our proposed control system to autonomously adapt itself in order to overcome fault conditions such as the loss of steering/actuation or traction of individual wheels but equally well handles changed operational conditions such as retracted wheels or a dynamically changed drive geometry.
|Effective start/end date||1/10/07 → 31/12/09|