Optimal Design of Cooperative Standing-Up Motion for Care Worker and Receiver

This paper considers an optimal design problem of cooperative standing-up motion for the care worker and receiver. To overcome the disadvantage of the receding horizon control (model predictive control) strategy in the previous work in terms of the admissible horizon length and the extream sensitivity of the feasibility on the weights, we revisit the numerical methods to solve the nonlinear optimal control problem. Two algorithms, the differential dynamic programming and the sequential quadratic programming are used to solve the problem. Another technical point is the modeling of a composite motion consisting of two people. The issue on the dynamics of the closed-links system is investigated. The effectiveness of the proposed method is demonstrated by generating the motions corresponding to several scienarios.