Task Planning for Cooperating Self-Reconfigurable Mobile Fixtures

The work solves the problem of task and motion planning of a self-reconfigurable fixture system. A feasible solution is a key requirement for the viability of such systems, which have raised hopes of overcoming the deficiencies that more traditional fixtures are recognized to have in the dynamic conditions of modern manufacturing, with its increasing emphasis on flexibility, adaptability, and automation. The paper proposes an application-independent approach for the generation of a time-relevant action plan for the locomotion, reconfiguration, and positioning of two or more mobile robotic fixtures. The fixture agents need to provide local support for a large workpiece during machining. The path planning problem is converted into a constraint satisfaction problem (CSP). The proposed approach is called Triple-CSP, as it applies an incremental state search to solve three hierarchical path planning tasks for the three components of each mobile fixture agent: a supporting head, a mobile base, and a parallel manipulator, respectively. A final time-related trajectory (time scaling of actions) for the agents' entire task execution is obtained. Thus, the planner takes into account all the relevant physical, geometrical, and time-related constraints.