Abstract:The calculation for optimized trajectories ofunrestricted multi-joint human arm in point-to-point reaching movement wasinvestigated. The planar motion equations of multi-joint arm were introducedat first, then the optimal criterion was constructed according to minimaleffort criterion, and the human arm point-to-point reaching movement wastreated as a two-point boundary value problem, finally an iterativealgorithm was presented to find the optimized arm trajectories and velocityprofile. The simulation results show that the equilibrium point or jointtorque varies smoothly，which avoids the large fluctuation of arm speed andreduces energy consumption when arm moves; the movement trajectory of handis roughly a straight line, and the corresponding velocity profile issingle-peaked and bell-shaped, which is in good agreement with the kinematicdata from the arm movement. Therefore the minimal effort criterion is alsoeffective for calculating the optimal movement trajectories of multi-jointarm.