A general control strategy of planar multi-link underactuated manipulator with passive last joint based on nilpotent approximation and intelligent optimization

We design a control strategy via the differential evolution algorithm (DEA) to solve the position control problem of a planar multi-link underactuated manipulator (PMLUM) with a passive last joint. According to the structure of the PMLUM, which can be regarded as a planar virtual Pendubot by the model reduction method. Considering the existence of the nilpotent approximation (NA) characteristic in the planar virtual Pendubot (PVP), the iterative steering method (ISM) is employed to make the PVP to its target angle. Simulation results show the effectiveness of the proposed strategy.