PREDICTIVE CONTROL TECHNIQUES IN BIPODAL LOCOMOTION
Active lower limb orthoses are devices intended to provide additional physical ability to the human musculoskeletal system or stimulate/correct human motor control activities. The implementation of these functions make that primarily a synergistic operation with the musculoskeletal system of the user must be insure, this of course for all activities involving the musculoskeletal system during which the orthosis braced is used. It is obvious that larger the spectrum of these activities is more the interest grew.
The mechanical system ensuring these locomotion function can be seen as a hybrid dynamic system and its control be considered through predictive control techniques. The evolution of the system’s state and the iterative optimization over a finite-horizon formulation of its control allows the inclusion of different objectives that are combined during its evolution (postural stability, stability of support, energy consumption, etc.) and all the constraints that act on the system (joint limits, saturation of generalized forces, etc.).
The presentation proposes an original approach to capture the hybrid form of the system in a predictive control framework.The resulting MPC problem takes the form of a quadratic, linearly constrained mixedinteger program (MIQP) which allows to determine, over a preview horizon, an optimal strategy between changes in the BoS and CoM behavior, subject to multiple constraints, maximizing balance and performance of a walking activity