For mobile platforms with steerable standard wheels it is necessary to precisely coordinate rotation and steering angle of their wheels. An established approach to ensure this is to represent the current state of motion in form of the Instantaneous Centre of Motion (ICM) and to derive a trajectory within this space. However, while control in the ICM space does guarantee adherence to the system's nonholonomic constraints, it does not avoid the system's singular configurations. Within this work we address the problem of singularity avoidance within the ICM space. Singularities related to the mathematical representation of the ICM are reduced by a reformulation of this representation. Furthermore, a controller based on artificial potential fields avoiding singular configurations of the robot by representing them as obstacles in the derived ICM space is designed. The resulting controller is particularized and analyzed w.r.t. the Care-O-bot 3 demonstrator.

This paper introduces Care-O-bot®3, a highly integrated and compact service robot with manipulation, navigation and vision capabilities. In particular, Care-O-bot®3 combines the best of available technology including a 7 DOF light-weight arm, an omnidirectional platform and many high-end sensors along with a sustainable, end user oriented design concept enabling many interaction possibilities.

In this contribution a robot assistant for handling and assembly tasks is presented. The main emphasis of PowerMate was to create a robot assistant that works together with a human worker that is conform to safety category 3 according to DIN ISO 954 and to use components suitable for industrial use, which leads to certain constrains on the possible control mechanisms. An overview of existing concepts of man-machine-cooperation is given. Different architectures for these kinds of robot assistants are discussed. A user-customizable motion control for PowerMate is presented. A description of the force-movement-calculations, the hardware and software architecture and the safety system of the robot assistant is given.