全方向康复步行训练机器人滑模变结构控制方法研究

发布时间：2018-07-03 18:58

本文选题：全方向康复步行训练机器人 + 变结构控制　；参考：《沈阳工业大学》2017年硕士论文

【摘要】：随着老龄人口的不断增长,由于疾病或者外力损伤所造成的运动性功能障碍患者越来越多,医学研究表明科学的康复训练能够促进患者恢复,其中康复机器人得到了快速的发展。康复机器人属于一类高度不确定性和易受外部扰动的非线性系统,易受负载质量、重心偏移、未建模动态、周围环境、机械形变、反馈信息测量误差等因素的影响,很难保证系统跟踪精度。针对以上问题学者们已经设计出诸多控制方法;然而这些控制方法主要以实现轨迹跟踪为目的,大部分忽视了康复机器人运动速度对患者的影响,或者以牺牲收敛时间为代价而达到一定的跟踪效果。本文主要以全方向康复步行训练机器人为研究对象,对具有重心偏移情况下动力学模型展开研究,采用变结构控制算法设计出相应的控制器,在确保患者安全和一定跟踪精度的前提下,实现速度受限和确定收敛时间的轨迹跟踪。主要研究内容如下:当系统跟踪误差较大时,康复机器人会产生较大的运动速度去消除跟踪误差。考虑到速度对康复患者安全的影响,文中首先定义了安全的受限速度,采用反演方法设计出了针对速度和轨迹的补偿算法;其次采用变结构的控制方法设计出可以直接限制速度的控制器;然后论证了系统的稳定性;最后对比了在系统速度受限情况下,设计速度和位移补偿项与不设计相应补偿项两种状态下的跟踪效果。通过仿真实验验证了控制策略的有效性,实现了速度受限的功能。另外从抑制系统的抖振和保证系统状态能够在有限时间内收敛到平衡点出发,在保证变结构控制的动态性能情况下,设计出一种新型控制器以提高轨迹的跟踪精度。文中提出一种具有自适应效果的改进双幂次趋近率去削弱系统的抖振,并通过对滑模面的重新设计确保了系统状态能够在有限时间内收敛。通过仿真验证该方法对系统的抖振具有很好的抑制效果,且系统误差收敛速度加快,验证了对期望轨迹跟踪效果具有非常明显的改善。
[Abstract]:With the increasing of aging population, there are more and more patients with motor dysfunction caused by disease or external force injury. Medical research shows that scientific rehabilitation training can promote patients' recovery. Among them, rehabilitation robot has been developed rapidly. Rehabilitation robot belongs to a kind of nonlinear system with high uncertainty and easy external disturbance. It is vulnerable to the influence of load mass, barycenter deviation, unmodeled dynamics, surrounding environment, mechanical deformation, measurement error of feedback information, etc. It is difficult to ensure the tracking accuracy of the system. In view of the above problems, many control methods have been designed by scholars. However, these control methods are mainly aimed at track tracking, and most of them ignore the effect of the speed of rehabilitation robot on patients. Or at the expense of convergence time to achieve a certain tracking effect. In this paper, taking the omnidirectional rehabilitation walking robot as the research object, the dynamic model with center of gravity deviation is studied, and the corresponding controller is designed by using variable structure control algorithm. On the premise of ensuring patient safety and certain tracking accuracy, track tracking with limited speed and fixed convergence time is realized. The main research contents are as follows: when the system tracking error is large, the rehabilitative robot will produce large motion speed to eliminate the tracking error. Considering the effect of speed on the safety of rehabilitated patients, the limited speed of safety is defined firstly, and the compensation algorithm for velocity and trajectory is designed by using inversion method. Secondly, the variable structure control method is used to design the controller which can directly limit the speed. Then, the stability of the system is demonstrated. The tracking effect of the design speed and displacement compensation term and the corresponding compensation term without the design. The effectiveness of the control strategy is verified by simulation experiments, and the speed limited function is realized. In addition, a new controller is designed to improve the tracking accuracy of the system by reducing the chattering and ensuring that the state of the system can converge to the equilibrium point in a finite time. Under the condition of ensuring the dynamic performance of the variable structure control, a new controller is designed to improve the tracking accuracy. In this paper, an improved double power convergence rate with adaptive effect is proposed to weaken the chattering of the system, and the state of the system can converge in a finite time by redesigning the sliding mode surface. The simulation results show that the proposed method has a good effect on the buffeting of the system, and the convergence rate of the system error is quickened, which verifies that the expected trajectory tracking effect is improved obviously.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP242

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