Biomechanical bipedal model with asymmetrical reference trajectories for sit-to-stand task

Human bipedal models behave symmetrically as well as asymmetrically depending upon nature of movement, task and orientation of the body. A bipedal model with full symmetry of limbs and movement is very redundant engineering design which has lots of unstable eigenvalues and poles. To avoid redundancy asymmetry is introduced which imposes coordination and controller design problem. In this paper, we are presenting a biomechanical bipedal model with 13 generalized coordinates of joint angles of right and left limbs in sagittal and frontal plane, a left foot translation. This model has no moment in right foot translation and asymmetrical reference trajectories in right and left limbs. An optimal controller design provides the feedback torque for stable sit-to-stand movement. Our results indicate the applicability of this model for stroke patients or subjects with paraplegic limbs.