Optimal control sequence for underactuated manipulators

Considers the problem of controlling an underactuated manipulator with less actuators than passive joints. The control methodology consists of dividing the passive joints in several groups, and of controlling one group at a time via its dynamic coupling with the actuators. Among the many possible control sequences for a given robot, we choose the optimal one based on the dynamic programming method. The optimization is based on a control cost defined as the reciprocal of the coupling index, a measure of the dynamic coupling available between the active and the passive joints of the manipulator. The detailed theory, computational procedures, simulation results, and experimental results are presented