空间机械臂柔性关节的位置及抑振控制研究

发布时间：2018-04-03 02:00

本文选题：柔性关节　切入点：动力学模型　出处：《北京交通大学》2015年硕士论文

【摘要】：目前,世界上大多数国家都十分重视对太空资源的利用和开发,空间机械臂的研究已经成为空间技术研究领域内的一个重要研究方向,利用空间机械臂完成一些太空作业任务具有重要的意义。由于,空间机械臂具有控制精度高、设计寿命长、可靠性高等特点,因此,对其设计和控制提出了很高的要求。本文重点针对空间机械臂系统的关键组成部分——柔性关节进行研究分析,对柔性关节的动力学模型、高精度位置控制和振动抑制控制等问题作了相关研究。首先,基于Lagrange方程得到空间机械臂柔性关节的简化动力学模型。应用Matlab/SimMechanics仿真软件进行动力学仿真分析,验证了动力学模型的有效性和可实现性,为后面的控制策略的研究提供了重要的理论依据。针对柔性关节的线性扭转弹簧模型和弹簧阻尼器模型,采用常规的PD控制器对其进行仿真实验,对比分析了不同输入信号、控制器参数以及非线性阻尼对系统的影响,仿真结果表明,要实现柔性关节的高精度控制,需要进一步对其控制策略进行研究。其次,针对空间机械臂柔性关节的高精度位置控制进行研究。考虑了非线性因素对系统的影响,通过分析半闭环PD位置控制和全闭环PD位置控制的优缺点,设计了一种双位置反馈PD控制器来提高关节输出端的位置轨迹跟踪精度,为了实现更高精度的位置轨迹跟踪控制,针对PD控制器的缺陷,采用自抗扰控制器,设计双位置反馈自抗扰控制策略,通过对柔性关节系统进行仿真实验表明,所设计的控制策略不仅能够提高系统的轨迹跟踪精度,还能克服摩擦等非线性因素对系统性能的影响。再次,针对空间机械臂柔性关节的振动抑制进行研究。通过对柔性关节的振动状态分析,采用了力矩负反馈控制来实现关节的抑振,考虑到关节力矩常常受到干扰信号的影响,在此基础上,对力矩负反馈控制进行改进,设计力矩负反馈PD控制器,仿真结果表明,力矩负反馈PD控制在实现抑振的同时可较好的避免干扰信号的影响。鉴于力矩负反馈PD控制器不能兼顾抑振效果和轨迹跟踪精度的问题,设计振动力矩反馈控制器,仿真实验表明,该方法在实现有效抑振的同时能够保持轨迹跟踪的精度。最后,为了满足空间机械臂柔性关节设计指标的要求,既能保证高精度的位置控制的同时实现有效抑振,对空间机械臂柔性关节进行位置／力混合控制,设计四种不同的混合控制策略,通过仿真结果表明,四种混合控制策略均能满足设计指标的要求,且双位置反馈自抗扰控制+振动力矩反馈控制的混合控制效果最为理想。
[Abstract]:At present, most countries in the world attach great importance to the utilization and development of space resources, and the research of space manipulator has become an important research direction in the field of space technology research.It is of great significance to use space manipulator to accomplish some space tasks.Because the space manipulator has the characteristics of high control precision, long design life, high reliability and so on, the design and control of space manipulator are required to be very high.In this paper, the key component of space manipulator system, flexible joint, is studied, and the dynamic model of flexible joint, high precision position control and vibration suppression control are studied.Firstly, the simplified dynamic model of flexible joints of space manipulator is obtained based on Lagrange equation.The effectiveness and realizability of the dynamic model are verified by using the Matlab/SimMechanics simulation software, which provides an important theoretical basis for the study of the control strategy in the future.The linear torsion spring model and spring damper model of flexible joints are simulated by conventional PD controller. The effects of different input signals, controller parameters and nonlinear damping on the system are compared and analyzed.The simulation results show that in order to achieve high precision control of flexible joints, it is necessary to further study its control strategy.Secondly, the high precision position control of flexible joints of space manipulator is studied.Considering the influence of nonlinear factors on the system, by analyzing the advantages and disadvantages of semi-closed-loop PD position control and full-closed-loop PD position control, a dual-position feedback PD controller is designed to improve the tracking accuracy of joint output.In order to achieve a higher precision position tracking control, aiming at the defects of PD controller, a dual position feedback active disturbance rejection control strategy is designed. The simulation results of the flexible joint system show that,The designed control strategy can not only improve the tracking accuracy of the system, but also overcome the influence of nonlinear factors such as friction on the performance of the system.Thirdly, the vibration suppression of flexible joints of space manipulator is studied.Based on the analysis of the vibration state of flexible joints, the torque negative feedback control is used to control the joint vibration. Considering that the joint torque is often affected by the disturbance signal, the torque negative feedback control is improved.A torque negative feedback PD controller is designed. The simulation results show that the torque negative feedback PD control can effectively avoid the influence of disturbance signal while suppressing vibration.In view of the fact that the torque feedback PD controller can not take into account the vibration suppression effect and trajectory tracking accuracy, the vibration torque feedback controller is designed. The simulation results show that the proposed method can effectively suppress vibration and maintain the track tracking accuracy at the same time.Finally, in order to meet the design requirements of space manipulator flexible joint, it can not only guarantee high precision position control, but also achieve effective vibration suppression, and carry out position / force hybrid control for space manipulator flexible joint.Four different hybrid control strategies are designed. The simulation results show that the four hybrid control strategies can meet the requirements of the design index, and the hybrid control effect of the dual position feedback ADRC vibration torque feedback control is the most ideal.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V423

【参考文献】