A power series based inverse-kinematics solution of a humanoid robot hand with coupled joints

Since it is difficult to obtain a closed-form solution of inverse-kinematics for a humanoid robot hand with coupled joints due to its nonlinearity induced by trigonometric transcendental function, most solutions achieved in early studies were numerical ones. In this paper, an inverse-kinematics algorithm based on the power series is presented, by which the nonlinear equation including trigonometric transcendental function can be converted into an algebraic equation. An approximate solution is derived firstly; with 1-D linear interpolation for errors compensating, the accurate solution can then be achieved. In calculation example, the algorithms based on power series expanded to quadratic and quartic terms are used to calculate the accurate joint angles. Simulation results demonstrate effectiveness of the proposed inverse kinematics method.