This paper addresses the problem of finding robot configurations to grasp assembly parts during a sequence of collaborative\nassembly operations. We formulate the search for such configurations as a constraint satisfaction problem (CSP). Collision\nconstraints in an operation and transfer constraints between operations determine the sets of feasible robot configurations.We\nshow that solving the connected constraint graph with off-the-shelf CSP algorithms can quickly become infeasible even for\na few sequential assembly operations. We present an algorithm which, through the assumption of feasible regrasps, divides\nthe CSP into independent smaller problems that can be solved exponentially faster. The algorithm then uses local search\ntechniques to improve this solution by removing a gradually increasing number of regrasps from the plan. The algorithm\nenables the user to stop the planner anytime and use the current best plan if the cost of removing regrasps from the plan\nexceeds the cost of executing those regrasps. We present simulation experiments to compare our algorithm�s performance to\na naive algorithm which directly solves the connected constraint graph. We also present a physical robot system which uses\nthe output of our planner to grasp and bring parts together in assembly configurations.
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