Fuzzy Torque Control of the Bionic Flexible Manipulator Actuated by Pneumatic Muscle Actuators

A bionic flexible manipulator driven by pneumatic muscle actuator(PMA)can better reflect the flexibility of the mechanism.Current research on PMA mainly focuses on the modeling and control strategy of the pneumatic manipulator system.Compared with traditional electro-hydraulic actuators,the structure of PMA is simple but possesses strong nonlinearity and flexibility,which leads to the difficulty in improving the control accuracy.In this paper,the configuration design of a bionic flexible manipulator is performed by human physiological map,the kinematic model of the mechanism is established,and the dynamics is analyzed by Lagrange method.A fuzzy torque control algorithm is designed based on the computed torque method,where the fuzzy control theory is applied.The hardware experimental system is established.Through the co-simulation contrast test on MATLAB and ADAMS,it is found that the fuzzy torque control algorithm has better tracking performance and higher tracking accuracy than the computed torque method,and is applied to the entity control test.The experimental results show that the fuzzy torque algorithm can better control the trajectory tracking movement of the bionic flexible manipulator.This research proposes a fuzzy torque control algorithm which can compensate the error more effectively,and possesses the preferred trajectory tracking performance.

Rotation Control of a 3-DOF Parallel Mechanism Driven by Pneumatic Muscle Actuators

The pneumatic muscle actuator(PMA)has many advantages,such as good flexibility,high power/weight ratio,but its nonlinearity makes it difficult to build a static mathematical model with high precision.A new method is proposed to establish the model of PMA.The concept of hybrid elastic modulus which is related to the static characteristic of PMA is put forward,and the energy conservation law is used to achieve the expression of the hybrid elastic modulus,which can be fitted out based on experimental data,and the model of PMA can be derived from this expression.At the same time,a 3-DOF parallel mechanism(a new bionic shoulder joint)driven by five PMAs is designed.This bionic shoulder joint adopts the structure of two antagonistic PMAs actualizing a rotation control and three PMAs controlling another two rotations to get better rotation characteristics.The kinematic and dynamic characteristics of the mechanism are analyzed and a new static model of PMA is used to control it.Experimental results demonstrate the effectiveness of this new static model.

A Survey on Pneumatic Muscle Actuators Modeling

The aim of this article is to provide a survey on the most popular modeling approaches for PMAs （pneumatic muscle actuators）. PMAs are highly non-linear pneumatic actuators where their elongation is proportional to the interval pressure. During the last decade, there has been an increase in the industrial and scientific utilization of PMAs, due to their advantages such as high strength and small weight, while various types of PMAs with different technical characteristics have appeared in the literature. This article will： （a） analyse the PMA＇s operation from a mathematical modeling perspective; （b） present their merits and drawbacks of the most common PMAs; and （c） establish the fundamental basis for developing industrial applications and conducting research in this field.

STUDY ON THE CONTROL OF SINGLE PNEUMATIC MUSCLE ACTUATOR

The control of single pneumatic muscle actuator is studied, as one basic partof research on the parallel-robot arthrosis actuated by pneumatic muscle actuators. Experimentsshow that a self-modified fuzzy-PID controller is obviously effective for its position servo and asimple PID controller is good for its force track.

Position Control of Single Pneumatic Muscle Actuator

The PID, fuzzy, self-organized fuzzy and self-organized fuzzy-PID controllers are adopted in the position control of single pneumatic muscle actuator. Experiments show that the self-organized fuzzy-PID is obviously effective for the position control of single pneumatic muscle actuator, which can realize precision within 0.3 mm and withstand 18?N variable load plus about 36?N fixed load. It is relatively precise and robust.

Angle Control of a Pneumatically Driven Musculoskeletal Model Based on Coordination of Agonist-Antagonist Muscle

In recent years, researchers have been actively pursuing research into developing robots that can be useful in many fields of industry （e.g., service, medical, and aging care）. Such robots must be safe and flexible so that they can coexist with people. Pneumatic actuators are useful for achieving this goal because they are lightweight units with natural compliance. Our research focuses on joint angle control for a pneumatically driven musculoskeletal model. In such a model, we use a one-degree-of-freedom joint model and a five-fingered robot hand as test beds. These models are driven by low pressure-driven pneumatic actuators, and mimic the mechanism of the human hand and musculoskeletal structure, which has an antagonistic muscle pair for each joint. We demonstrated a biologically inspired control method using the parameters antagonistic muscle ratio and antagonistic muscle activity. The concept of the method is based on coordination of an antagonistic muscle pair using these parameters. We have investigated the validity of the proposed method both theoretically and experimentally, developed a feedback control system, and conducted joint angle control by implementing the test beds.

一种新型气动肌肉执行器的结构设计与控制研究

传统的气动肌肉执行器存在结构单一、功能低下的问题,为此,基于蛇在蜿蜒运动时的灵感,提出了一种具有向两个相反方向弯曲能力的双弯曲型气动肌肉执行器(DB-PMA)。首先,以传统的收缩式气动肌肉执行器(CPMA)为切入点,描述了DB-PMA的机械结构,包括DB-PMA仿生学设计基础以及DB-PMA的基本机械结构;然后,在“放松”、“加压”、“特殊”3种不同状态下,展开了对DB-PMA的相关运动学分析;并基于DB-PMA进行了实验,对实验结果进行了分析,将其与传统CPMA进行了性能方面的对比;最后,基于该执行器设计了一款软体机械臂,对该机械臂的性能进行了展示,并使用两种方法对其进行了优化改进,并对改进后的机械臂做了分析。研究结果表明:通过第一种改进方法可以使机械臂的最大弯曲角度增加到213°,通过第二种改进方法可以明显地使机械臂的控制更精准;相较于最初的机械臂,两种改进方法均能使机械臂的性能得到了明显的优化与改善。

Ultralong Stretchable Soft Actuator(US2A):Design,Modeling and Application

Actuator plays a significant role in soft robotics.This paper proposed an ultralong stretchable soft actuator(US2A)with a variable and sizeable maximum elongation.The US2A is composed of a silicone rubber tube and a bellows woven sleeve.The maximal extension can be conveniently regulated by just adjusting the wrinkles’initial angle of the bellows woven sleeve.The kinematics of US2A could be obtained by geometrically analyzing the structure of the bellows woven sleeve when the silicone rubber tube is inflated.Based on the principle of virtual work,the actuating models have been established:the pressure-elongation model and the pressure-force model.These models reflect the influence of the silicone tube’s shell thickness and material properties on the pneumatic muscle’s performance,which facilitates the optimal design of US2A for various working conditions.The experimental results showed that the maximum elongation of the US2A prototype is 257%,and the effective elongation could be variably regulated in the range of 0 and 257%.The proposed models were also verified by pressure-elongation and pressure-force experiments,with an average error of 5%and 2.5%,respectively.Finally,based on the US2A,we designed a pneumatic rehabilitation glove,soft arm robot,and rigid-soft coupling continuous robot,which further verified the feasibility of US2A as a soft driving component.

气动人工肌肉关节的自抗扰控制

气动人工肌肉关节系统是一个强非线性时变自平衡2阶系统,鉴于传统控制方法难以克服控制精度、调节速度和稳定性之间的矛盾,设计了一种2阶自抗扰控制器.采用3阶扩张状态观测器实时估计未建模型部分及外界扰动,对系统进行线性补偿,并利用非线性反馈机制提高控制效率,在保证稳定性的前提下,提高调节速度和控制精度,使得系统的稳态精度小于0.1°,跟踪精度小于0.5°.试验证明,即使在系统模型部分已知或未知的情况下,系统采用自抗扰控制仍然可以使控制效果达到令人满意的程度.

柔性气动执行器的研究现状和趋势

介绍了当前各种柔性气动执行器的研究背景、结构原理和最新研究进展 。

气动人工肌肉驱动仿人肩关节机器人的设计及力学性能分析

柔索驱动球关节机器人采用柔索替代连杆作为机器人的传动元件,结合了并联机构和柔索传动的优点.文中提出了一种新型带有万向球轴承的仿人肩关节并联机器人,它由多支气动人工肌肉驱动,由于万向球驱动机构的引入,机器人可实现空间的三维转动.介绍了该机器人的机构构型,并对其进行了力学性能分析.该机器人的运动范围及负重能力达到并超过了人体肩关节性能指标的1/2.相比其他并联机器人,该设计具有结构简单、旋转范围大、输出力矩大等特点.

一种新型气动执行元件——气动人工肌肉

气动人工肌肉是一种结构简单、功率自重比大、有良好柔性、不会损害操作对象的新型气动执行元件。概述了气动人工肌肉的研究现状 ,分析了气动人工肌肉的优缺点和应用中存在的问题。在此基础上 ,指出目前气动人工肌肉的研究尚处于起步阶段 ,并给出了其有待进一步研究的方向。

气动人工肌肉系统动态特性研究

提出将气动人工肌肉视为带有弹性负载的变截面气缸的观点,方便地建立了气动人工肌肉系统动态数学模型。将气动人工肌肉的工作过程划分为等容充气、充气收缩、排气伸长和等容排气四个部分,通过仿真和实验研究对气动人工肌肉进行了特性分析。实验结果表明了所建立的动态数学模型的正确性,为气动人工肌肉应用研究奠定了基础。

气动人工肌肉驱动器的研究现状及发展趋势

气动人工肌肉驱动器作为一种新型的机器人驱动器,以其简单的设计和独特的仿生性一直受到人们的关注,自其问世 以来,人们对它的研究方兴未艾。本文介绍了气动人工肌肉驱动器的结构与特点,列举了丰富的应用实例,总结了目前国内外的 研究现状,并展望了这种新型气动驱动器的发展趋势。

气动人工肌肉驱动球面并联机器人的力控制研究

分析了具有柔索冗余驱动特点的静力关系 ,研究了力控制的智能控制算法及策略 ,在建立的实验样机上达到了良好的力伺服性能 .将气动人工肌肉的被动柔顺性与位置控制到力控制过渡的主动柔顺控制策略结合 。

气动人工肌肉并联机器人平台

提出一种基于气动人工肌肉的新型3自由度并联机器人平台,该机器人平台结构简单,具有3转动自由度。在对该新型3自由度并联机器人平台运动学和动力学特性理论分析的基础上,采用模糊变结构控制策略设计了新型3自由度并联机器人平台的两层滑模模糊变结构控制器,并建立了试验系统,开展了新型3自由度并联机器人平台的试验研究,其最大位置跟踪误差0．3 mm,当气源压力改变后,最大跟踪误差仍小于0．6 mm。试验结果表明,采用气动人工肌肉作为驱动装置设计的3自由度并联机器人平台是可行的,两层滑模模糊变结构控制策略对于该系统是适合的。

基于PSO的气动人工肌肉驱动关节优化的研究

提出在气动人工肌肉驱动的关节系统中,存在一个最优关节设计,包括关节半径、肌肉附着点最优位置等,使得对同一系统输出转矩达到最优.通过分析气动人工肌肉静态特性模型,推导出关节静特性模型.改变气动人工肌肉的状态参数进行仿真,得到关节半径变化、肌肉附着点变化与关节输出转矩、收缩量之间的关系,并利用PSO计算出最优关节半径与肌肉附着点最优位置.此分析方法与结果对气动肌肉驱动的仿生手臂的结构设计起到有效的指导作用.

气动肌腱驱动的拮抗式仿生关节位置/刚度控制

仿生关节是四足仿生机器人实现灵活跳跃、奔跑等高速复杂运动的基本要素。针对现有气动肌腱驱动的仿生关节难以实现设定刚度下的高精度位置控制问题,提出一种基于模糊神经网络补偿控制的拮抗式仿生关节位置/刚度控制新方法。建立关节位置/刚度解算模型,根据关节驱动力矩及设定刚度计算气动肌腱的理论充气压力;建立关节输出刚度计算模型,根据关节输出位置及气动肌腱的实际充气压力计算仿生关节的实际输出刚度;采用由模糊神经网络补偿控制器、PID控制器和模糊神经网络辨识器构成的模糊神经网络补偿控制结构实现对仿生关节的高精度位置控制。以FESTO公司MAS型气动肌腱驱动的拮抗式仿生关节为控制对象,进行关节位置/刚度控制的试验研究,对比PID控制和模糊神经网络补偿控制的位置控制精度,探究仿生关节刚度的动态响应。试验结果表明:模糊神经网络补偿控制方法的位置控制精度显著优于PID控制方法,位置控制精度由3°提高到0.6°;同时两种控制方法均能较好地跟随关节设定刚度,刚度跟踪精度均在1 N?m/rad内。

气动人工肌肉驱动球面并联机器人的位置控制研究

研究将气动人工肌肉驱动器应用于柔索驱动三自由度球面并联机器人机构,介绍了该机器人的运动学模型,提出一种简便的轨迹规划方法,在建立的实验测控系统中,应用含并联机器人的位置逆解和对气动人工肌肉的智能PID控制的位置控制算法,实现对机器人末端的位置控制,通过机器人的位置正解验证了位置控制的控制效果.

基于气动肌肉群驱动球关节机器人结构及阻抗控制

气动肌肉(Pneumatic muscle actuator,PMA)是仿生机器人研究的重点,为此,设计一种由气动肌肉群驱动的3自由度球关节机器人,并对其进行运动学分析。根据其运动学逆解,提出气动肌肉群位置控制策略;同时,提出基于运动学逆解及能量最优原则气动肌肉群力控制策略;设计基于气动肌肉位置群及力群的含位置PID内环的阻抗控制器。试验结果表明,单纯的位置控制精度比较高,可达0.3°,但造成输出力矩失控;阻抗控制虽然在一定程度上牺牲了位置控制精度,但可以对输出力矩进行柔顺控制。