关键词: 香蕉采摘机器人, 牛顿迭代法, 逆运动学求解, 正运动学建模

Abstract: The inverse kinematics solution of the banana picking robot with four degrees of freedom should be resolved according to the target position and attitude of the fruit handle clamping actuator at each sampling time. The two degrees of freedom of the base rotation angle and end rotation angle of the banana picking robot, its analytical solution of inverse kinematics is resolved according to the geometric relations. However, the two degrees of freedom of the horizontal displacement and vertical displacement are nonlinear due to their mutual coupling, so it is difficult to resolve their inverse kinematics solutions by analytical solution methods. Therefore, a numerical solution method for inverse kinematics of the banana picking robot based on Newton iteration method is proposed. Firstly, according to the mechanical structure and geometric relations of picking robot, the forward kinematics model solving the position and attitude of the fruit handle clamping actuator by four degrees of freedom is established, then the equations satisfied by the two degrees of freedom of horizontal displacement and vertical displacement are constructed, and the inverse matrix of its Jacobian matrix is obtained. Then the Newton iterative algorithm designed in this paper is used to resolve the inverse kinematics solution of horizontal displacement and vertical displacement according to the target position and attitude of the fruit handle clamping actuator. The experimental results show that the inverse kinematics solution of the base rotation angle and end rotation angle of the picking robot solved by the method proposed in this paper has no error. For the inverse kinematics solution of horizontal displacement and vertical displacement, when the fruit handle clamping actuator takes any target position and attitude, and the initial value of Newton iteration takes a fixed initial position and attitude, the error of inverse kinematics solution with two Newton iterations is less than 01 mm, and has no error with three Newton iterations. When the fruit handle clamping actuator takes the target position and attitude at each sampling time in continuous motion, and the initial value of Newton iteration takes the inverse kinematics solution of previous sampling time, only one iteration is needed to obtain the highprecision inverse solution.

Key words: banana picking robot, Newtons iteration method, solving inverse kinematics, forward kinematics modeling