ASSEMBLY SCHEDULING FOR AN INTEGRATED 2-ROBOT WORKCELL

An assembly sequence planning scheme, giving the time optimal solution for a two-robot cell, is presented. The scheme is based on dynamic pr ogramming, and the time optimum assembly sequence is generated in two stages. In stage one, an initial candidate sequence is derived. The st age-one algorithm is computationally efficient, the complexity being ( (log n/k), where n is the number of elements in k groups. It also give s near-optimal results. Expression for the lower bounds for the total assembly time are derived in order to assess the departure from optima lity of the stage-one sequence. In stage two, the initial candidate se quence is optimized using an iterative technique to yield the time opt imal sequence. The scheme is extended to account for precedence constr aints. It can also be extended for assembly cells with more than two r obots. The scheme is tested using computer simulations, and some test results are presented. For the problems solved (typically involving 20 elements), the computational times were less than 5 sec in an Apollo 300 workstation. (C) 1997 Elsevier Science Ltd.