基于模糊力矩的机械臂轨迹跟踪控制方法研究

发布时间：2018-01-03 18:03

本文关键词：基于模糊力矩的机械臂轨迹跟踪控制方法研究　出处：《大连理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：随着科学技术的飞速发展,机器人技术在工业生产、日常生活、军事以及太空探索等领域的应用日趋广泛。机械臂作为应用最为广泛的一类机器人,其多输入多输出的控制系统具有耦合性、非线性以及时变性等特点。机械臂的轨迹跟踪控制作为机械臂的研究重点,要求机械臂各关节的实际轨迹跟踪给定的期望轨迹。在机械臂的动力学模型已知的前提下,现有的控制算法可以解决机械臂的轨迹跟踪控制问题；但是在实际情况下,由于机械臂关节存在有耦合、摩擦等非线性因素以及负载变化等外部扰动的影响,机械臂的动力学模型往往不能精确得到。因此,研究更具有适应性的机械臂控制方法是有价值的。本文以带有不确定项的机械臂控制系统为研究对象,针对机械臂的轨迹跟踪控制算法进行研究。首先,本文运用D-H方法对机械臂进行运动学分析,在此基础上,利用拉格朗日函数建立三自由度机械臂的动力学模型,并且对其进行必要的化简进而提出本文的机械臂模型。其次,实现了基于PD方法的定点控制和基于计算力矩法的时变轨迹跟踪控制,从仿真结果可以看出计算力矩法的轨迹跟踪控制精度不高。针对这种情况,本文提出在计算力矩法的基础上加入模糊控制,综合模糊控制与计算力矩方法的优点,使模糊力矩方法对机械臂轨迹跟踪误差降低的同时,增加了计算力矩法内控制回路的自适应性。最后,针对机械臂动力学模型不确定部分的控制,在模糊力矩控制的基础上提出了两种基于变结构补偿的模糊力矩控制方法,即基于变结构补偿的模糊力矩控制和基于模糊变结构补偿的模糊力矩控制。机械臂的动力学模型分为标称部分与不确定部分,采用“分而治之”的思想,对于机械臂的标称部分采用模糊力矩控制,对于机械臂的不确定部分采用集中补偿控制的方法,设计不确定部分的包络函数,采用变结构控制进行补偿,两部分控制器的综合输出作为被控对象的控制输入。从仿真结果可以看出带有补偿的控制算法控制精度高,位置轨迹误差小,各关节能够快速跟踪期望轨迹,从而验证了控制器的有效性。利用基于模糊变结构补偿的模糊力矩控制方法能够使得机械臂达到渐进稳定,位置跟踪误差小,还可以减小变结构控制的抖振。
[Abstract]:With the rapid development of science and technology, robot technology is widely used in the fields of industrial production, daily life, military affairs and space exploration. The multi-input and multi-output control system has the characteristics of coupling, nonlinear and time-varying, etc. The trajectory tracking control of the manipulator is the focus of the research of the manipulator. The actual trajectory of each joint of the manipulator is required to track a given desired trajectory. With the dynamic model of the manipulator known, the existing control algorithms can solve the trajectory tracking control problem of the manipulator. However, in practice, because of the coupling of the manipulator joints, friction and other nonlinear factors, as well as external disturbances such as load changes, the dynamic model of the manipulator is often unable to be accurately obtained. It is valuable to study more adaptive manipulator control methods. In this paper, the trajectory tracking control algorithm of manipulator with uncertainty is studied. In this paper, the kinematics of the manipulator is analyzed by using D-H method. On this basis, the dynamic model of the three-degree-of-freedom manipulator is established by using the Lagrange function. And the necessary simplification of the robot arm model is put forward. Secondly, the fixed-point control based on PD method and time-varying trajectory tracking control based on calculating torque method are realized. It can be seen from the simulation results that the precision of trajectory tracking control by calculating torque method is not high. In view of this situation, fuzzy control is put forward on the basis of calculating torque method. Combining the advantages of fuzzy control and torque calculation method, the fuzzy torque method can reduce the tracking error of the manipulator and increase the self-adaptability of the internal control loop of the calculation torque method. Based on fuzzy torque control, two fuzzy torque control methods based on variable structure compensation are proposed for the uncertain part of manipulator dynamics model. That is, fuzzy torque control based on variable structure compensation and fuzzy torque control based on fuzzy variable structure compensation. The dynamic model of manipulator is divided into nominal part and uncertain part, and the idea of "divide and conquer" is adopted. The fuzzy torque control is used for the nominal part of the manipulator and the centralized compensation control method is used for the uncertain part of the manipulator. The envelope function of the uncertain part is designed and the variable structure control is used to compensate. The integrated output of the two-part controller is used as the control input of the controlled object. From the simulation results, it can be seen that the control algorithm with compensation has high control accuracy, small position trajectory error, and each joint can track the desired trajectory quickly. The fuzzy torque control method based on fuzzy variable structure compensation can make the manipulator achieve asymptotic stability, and the position tracking error is small, and the chattering of variable structure control can be reduced.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TP241

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