An integrated control-structure design for manipulators with flexible links

Integrated optimization techniques for mechatronic systems aim at designing simultaneously the trajectory, the control system and the mechanical structure in order to minimize a performance index. The key advantage of such an integrated approach is the capability to search in a wide design space, to account for many dynamic couplings in an early design stage and to avoid simplifying assumptions which would induce a suboptimal design. This work considers that technique for robotic manipulators with flexible links. It is known that a flexible multibody system is often non-minimum phase, here, no restriction is imposed to avoid it. This allows a free choice of the optimization process to select a lighter weight controlled system. Furthermore, the amplitudes of the non-actuated degrees-of-freedom should be reduced in order to limit bodies deformation. The mechanical model is derived using a nonlinear finite element method, which is a useful approach to represent systems with elastic bodies. An optimal control problem is considered to perform that integrated analysis and its time dicretization relies the direct transcription method.