Analysis of statics performance for a novel elbow joint of agricultural robot

For raising automation level of farm operation, improving popularity and adaptability of agricultural robot and advancing its service efficiency, a novel elbow joint of agricultural robot was proposed based on 2-D orthogonal spherical parallel mechanism. The architecture of the mechanism was comprised of a moving platform attached to a frame through two linkages, and the moving platform relative to the frame had two-rotation-freedom. Compared with the others robot elbow joint, the elbow joint had the advantage of structure symmetry, easy assembly, good kinematics character and large workspace. In this paper, the statics performance of the novel elbow joint of agricultural robot was analyzed. Firstly, the static transmission equation of the elbow joint was established by using the principle of virtual works. Further, the force Jacobian matrix was introduced into the statics performance evaluation index by using the norm in Matrix theory, and the torque input stability evaluation index as well as the torque transitivity evaluation index were defined, and the performance atlas of the statics performance evaluation indexes were plotted at the work spaces of the elbow joint. Results showed that the statics transitivity evaluation index and the torque input stability evaluation index of the novel elbow joint presented a symmetric distribution, and the statics transitivity decreased as the angle increasing, and had good static performance and motion stability at initial position nearby 50% range. Important information for optimization design in the novel elbow joint of agricultural robot was provided in this paper.