Calculation for optimized movement trajectories of human multi-joint arm

The calculation for optimized trajectories of unrestricted multi-joint human arm in point-to-point reaching movement was investigated. The planar motion equations of multi-joint arm were introduced at first, then the optimal criterion was constructed according to minimal effort criterion, and the human arm point-to-point reaching movement was treated as a two-point boundary value problem, finally an iterative algorithm was presented to find the optimized arm trajectories and velocity profile. The simulation results show that the equilibrium point or joint torque varies smoothly, which avoids the large fluctuation of arm speed and reduces energy consumption when arm moves; the movement trajectory of hand is roughly a straight line, and the corresponding velocity profile is single-peaked and bell-shaped, which is in good agreement with the kinematic data from the arm movement. Therefore the minimal effort criterion is also effective for calculating the optimal movement trajectories of multi-joint arm.