Bipedal modeling and decoupled optimal control design of biomechanical sit-to-stand transfer

We present the development of a 3D bipedal robotic model with thirteen generalized coordinates, and decoupled optimal controller design for the control of biomechanical sit-to-stand (STS) transfer. The non-linear model developed in Maple DynaFlexPro environment has three frontal and seven sagittal degrees of freedom (DOF). Three holonomic constraints ensure stationary foot placement during performance of the STS task. The controller design proceeds by decoupling the constrained and unconstrained DOF. We propose H₂ and H_infin optimal control designs for feedback control of joint torques in the constrained and unconstrained planes, respectively. We provide analytical and computer simulation results to show the applicability and performance of the decoupling controller for the control of STS task.