【作者】 刘志军；

【导师】 张永顺； 朱祥龙；

【作者基本信息】 大连理工大学 ， 机械工程， 2024， 硕士

【摘要】 随着航天自主对接、远程遥控医疗、精密装配以及自动化技术的高速发展,对机器人手腕关节的性能要求越来越高,能实现多自由度运动的球形电机关节系统有望替代传统多电机串联手腕关节系统。与机械传动关节相比,多自由度电机具有集成度高、转动自由度多、传动链简单、无机械间隙,运动时可避免非线性摩擦力等优点,可望显著提高柔顺控制响应速度、精度和稳定性。因此,多自由度球型电机己经成为机器人技术的研究热点。其中永磁球形电机具有响应速度快、结构紧凑、系统效率高等优点,是一种理想的关节驱动方式。针对当前球型关节存在电磁驱动结构复杂,运动存在耦合,磁场精确建模困难,磁矩奇异性等问题,本文提出一种基于旋转定轴效应的永磁柔性球型手腕关节,即永磁柔性球型关节在同轴随动磁矩驱动下,输出轴轴线趋近旋转磁场法向量方向,并会最终与其重合。通过改变旋转磁场的法向量方向,便可控制关节输出端的方位,实现对关节的控制。永磁柔性球型关节由三轴正交组合线圈和万向随动机构组成,作为定子的三轴正交组合线圈产生的空间万向旋转磁场为驱动源,通过磁场内同步旋转永磁体转子产生的同轴磁矩驱动实现关节侧摆、俯仰两自由度运动。由于所提出关节的是一种新型电磁直接驱动柔性关节,工作过程中受扰动时系统鲁棒性不足。通过建立永磁柔性球型关节的动力学模型,对关节的末端姿态详细描述,同时以抑制抖振和降低输出端轨迹误差为目标,采用非奇异快速终端滑模控制方法,针对切换增益引起的抖振问题,结合模糊控制算法对切换增益进行调节,使其实现自适应调整,从而完成对球型关节进行主动控制,完成了对期望轨迹高精度快速跟踪的控制目标。利用Lyapunov进行稳定性分析,证明了该控制系统的稳定性。通过Matlab/simulimk平台对所提出的滑模控制方法进行仿真计算,仿真结果证明该控制方法在轨迹跟踪控制时,具有较快的收敛速度和较低的跟踪误差,同时抑制了滑模控制中,因为控制律中切换增益的存在导致的抖振现象。最后利用制作出的样机进行试验,证明所提滑模控制方法有良好的鲁棒性,可以快速、准确跟踪关节输出末端的轨迹,同时解决了控制输入抖振较大的问题,提高了球型关节在复杂环境下的实用性。更多还原

【Abstract】 With the rapid development of aerospace autonomous docking,remote medical control,precision assembly,and automation technology,the performance requirements for robot wrist joints are becoming increasingly high.The spherical motor joint system that can achieve multi degree of freedom motion is expected to replace the traditional multi motor series wrist joint system.Compared with mechanical transmission joints,multi degree of freedom motors have advantages such as high integration,multiple rotational degrees of freedom,simple transmission chains,no mechanical clearances,and can avoid nonlinear friction during motion.They are expected to significantly improve the response speed,accuracy,and stability of compliant control.Therefore,multi degree of freedom spherical motors have become a research hotspot in robotics technology.The permanent magnet spherical motor has the advantages of fast response speed,compact structure,and high system efficiency,making it an ideal joint driving method.In response to the complex electromagnetic drive structure,coupled motion,difficulty in accurately modeling magnetic fields,and singularity of magnetic moments in current spherical joints,this paper proposes a permanent magnet flexible spherical wrist joint based on the rotational fixed axis effect.That is,the output axis of the permanent magnet flexible spherical joint approaches the direction of the normal vector of the rotating magnetic field under coaxial follow-up magnetic moment drive,and will eventually coincide with it.By changing the direction of the normal vector of the rotating magnetic field,the orientation of the joint output end can be controlled,achieving joint control.The permanent magnet flexible spherical joint is composed of a three-axis orthogonal combination coil and a universal follower mechanism.The spatial universal rotating magnetic field generated by the three-axis orthogonal combination coil as the driving source is used to drive the joint’s two degrees of freedom motion,including lateral sway and pitch,through the coaxial magnetic moment generated by synchronously rotating the permanent magnet rotor within the magnetic field.Due to the proposed joint being a new type of electromagnetic direct drive flexible joint,the system’s robustness is insufficient when disturbed during operation.By establishing a dynamic model of a permanent magnet flexible spherical joint and providing a detailed description of the joint’s end pose,with the goal of suppressing chattering and reducing output trajectory errors,a non singular fast terminal sliding mode control method is adopted.In response to the chattering problem caused by switching gain,a fuzzy control algorithm is used to adjust the switching gain adaptively,thereby achieving active control of the spherical joint and achieving the control goal of high-precision and fast tracking of the desired trajectory.The stability of the control system was demonstrated through stability analysis using Lyapunov.The proposed sliding mode control method was simulated using the Matlab/simulk platform,and the simulation results showed that the control method has a fast convergence speed and low tracking error in trajectory tracking control,while suppressing the chattering phenomenon caused by switching gain in the control law in sliding mode control.Finally,experiments were conducted using the produced prototype to demonstrate that the proposed sliding mode control method has good robustness and can quickly and accurately track the trajectory of the joint output end.At the same time,it solves the problem of large control input jitter and improves the practicality of spherical joints in complex environments.更多还原