农业机器人新型肘关节的静力学性能分析

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

    • 摘要: 为了提高农业自动化程度,改善农业机器人的通用性与适应性,提高农业机器人工作时的承载能力和利用率,该文提出一种基于二自由度正交球面并联机构的农业机器人新型肘关节。新型肘关节由2条支链组成,其动平台相对于机架具有2个转动自由度。新型肘关节与其它机器人的肘关节相比,具有良好的运动性能和较大的工作空间。对新型肘关节进行静力学性能分析,首先采用虚功原理的方法建立新型肘关节的静力学传递方程,该方法简化了肘关节的静力学计算过程;其次,利用矩阵理论中的范数知识,将力雅克比矩阵引入到静力学性能评价指标中,定义了肘关节的静力学力矩传递性能评价指标和力矩输入均衡性评价指标,分析了肘关节的静力学特性,并绘制了肘关节的静力学性能评价指标在工作空间内的性能图谱。分析结果表明,农业机器人新型肘关节的力矩传递性能指标和力矩输入均衡性能指标都呈对称分布,静力学力矩传递性能随着转角的增大而降低,在初始位置附近约50%的工作空间内具有良好的静力学特性和运动稳定性。该研究为农业机器人新型肘关节的优化设计提供参考。

       

      Abstract: 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.

       

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