Higher intelligence and greater autonomy of more advanced robot systems increase the requirements for the design of a flexible interface to control the system on different levels of abstraction. In the Kamro (Karlsruhe Autonomous Mobile Robot) project, for example, an autonomous mobile robot (Fig. 1) for assembly tasks is being developed which also has the capability of recovering from error situations Lath and Remold (1994). The autonomous mobile robot Kamro is a two-arm robot-system that consists of a mobile platform with an omni directional drive system, two Puma 260 manipulators, and different sensors for navigation, docking and manipulation.
Kamro is capable of performing assembly tasks (Fig. 2) autonomously. The tasks or robot operations can be described on different levels: assembly precedence graphs, implicit elementary operations (pick, place) and explicit elementary operations (grasp, transfer, fine motion, join, exchange, etc.). Given a complex task, it is transformed by the control architecture (Fig. 3) from assembly precedence graph level to explicit elementary operation level. The generation of suitable sequences of elementary operations depends on position and orientation of the assembly parts on the worktable while execution is controlled by the real-time robot control system. Status and sensor data which is given back to the planning-system enable Kamro to control the execution of the plan and correct it, if necessary.