Control of Manipulators With Redundancy

本项目主要研究冗余机械手的控制。目前使用的机械臂配置有6个自由度，这是实现末端执行器任意位置和方向所需的最小关节数。然而，由于整个机械手工作空间存在奇异性，六自由度机械手在功能上仅为五自由度机械手。本研究考察了额外或冗余自由度的利用，以应对奇点，并避免障碍物和关节和扭矩限制。本文涉及四个基本问题，包括：A)确定自运动（不引起末端执行器运动的关节运动）以优化性能标准，b)优化冗余机械手的性能标准（从一个标准平滑切换到另一个标准，并为不同标准分配不同的权重），C)基于任务的冗余利用导致需要较低关节扭矩的关节配置，d)自动调整末端执行器速度以避免障碍物，奇点和关节限制。本研究将把冗余机械手的应用扩展到更广泛的需要高速度和灵活性的任务中，从而证明冗余关节带来的额外成本是合理的。

This project addresses research in the control of redundant manipulators. Manipulators currently in use are configured with six degrees of freedom, which is the minimum number of joints required to achieve an arbitrary position and orientation of the end effector. However, due to singularities throughout the manipulator workspace, a six degree of freedom manipulator is functionally only a five degree of freedom manipulator. This research examines the utilization of additional, or redundant, degrees of freedom to contend with singularities, and to avoid obstacles and joint and torque limits. Four basic issues are addressed herein, including : a) determination of self motion (joint motion which does not cause end effector motion) to optimize performance criteria, b) optimization of performance criteria for redundant manipulators (smooth switching from one criteria to another and assignment of varying weights to different criteria), c) task based utilization of redundancy resulting in joint configurations requiring lower joint torques, and d) automatic adjustment of end effector speed to avoid obstacles, singularities, and joint limits. This research should expand the application of redundant manipulators to a wider range of tasks requiring high speed and dexterity, thus justifying the additional cost associated with redundant joints.