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.

Development and control of flexible pneumatic wall-climbing robot

A new kind of flexible pneumatic wall-climbing robot,named WALKMAN-I,was proposed. WALKMAN-I is basically composed of a flexible pneumatic actuator (FPA),a flexible pneumatic spherical joint and six suction cups. It has many characteristics of low-cost,lightweight,simple structure and good flexibility. Its operating principle was introduced. Then three basic locomotion modes,which are linear motion,curvilinear motion and crossing the orthogonal planes,were presented. The safety conditions of WALKMAN-I were discussed and built. Finally,the control system was designed and experiments were carried out. Experimental results show that WALKMAN-I is able to climb on the vertical wall surface along a straight line or a curved path,and has the ability of crossing orthogonal planes and obstacles. The maximum rotation angle reaches 90°,the maximum velocity reaches 5 mm/s,and the rotation angle and the moving velocity of WALKMAN-I can be easily controlled.

Basic Characteristics of a New Flexible Pneumatic Bending Joint

Several typical flexible pneumatic actuators （FPA） and different mechanical models describing their behaviors have been proposed, however, it is difficult to balance compliance and load capacity in conventional designs, and these models still have limitations in predicting behavior of FPAs. A new flexible pneumatic bending joint （FPBJ） with special anisotropic rigidity structure is proposed. The FPBJ is developed as an improvement with regard to existing types of FPA, and its principal characteristic is derived from the special anisotropic rigidity structure. With this structure, the load capacity in the direction perpendicular to bending plane is strengthened. The structure of the new FPBJ is explained and a mathematical model is derived based on Euler-Bernoulli beam model and Hook’s law. To obtain optimum design and usage, some key structure parameters and input-output characteristics are simulated. The simulation results reveal that the relationship between the structure parameters and FPBJ’s bending angle is nonlinear. At last, according to the simulation results, the FPBJ is manufactured with optional parameters and tested. The experimental results show that the joint’s statics characteristics are reflected by the mathematical model accurately when the FPBJ is deflated. The maximum relative error between simulation and experimental results is less than 6%. However, the model still has limitations. When the joint is inflated, the maximum relative error reaches 20%. This paper proposes a new flexible pneumatic bending joint which has sufficient load capacity and compliance, and the mathematical model provides theoretical guidance for the FPBJ’s structure design.

Design and control of integrated pneumatic dexterous robot finger

Based on flexible pneumatic actuator(FPA),bending joint and side-sway joint,a new kind of pneumatic dexterous robot finger was developed.The finger is equipped with one five-component force sensor and four contactless magnetic rotary encoders.Mechanical parts and FPAs are integrated,which reduces the overall size of the finger.Driven by FPA directly,the joint output torque is more accurate and the friction and vibration can be effectively reduced.An improved adaptive genetic algorithm(IAGA) was adopted to solve the inverse kinematics problem of the redundant finger.The statics of the finger was analyzed and the relation between fingertip force and joint torque was built.Finally,the finger force/position control principle was introduced.Tracking experiments of fingertip force/position were carried out.The experimental results show that the fingertip position tracking error is within ±1 mm and the fingertip force tracking error is within ±0.4 N.It is also concluded from the theoretical and experimental results that the finger can be controlled and it has a good application prospect.

Design and test of pneumatic artificial muscle driven variable trailing-edge camber wing

A variable camber wing driven by pneumatic artificial muscles is developed in this paper. Firstly, the experimental setup to measure the static output force of pneumatic artificial muscle is designed and the relationship between the static output force and the air pressure is investigated. Experimental results show that the static output force of pneumatic artificial muscle decreases nonlinearly with the increase of contraction ratio. Secondly, the model of variable camber wing driven by pneumatic artificial muscles is manufactured to validate the variable camber concept. Finally, wind tunnel tests are conducted in the low speed wind tunnel. It is found that the wing camber increases with the increase of air pressure. When the air pressure of PAMs is 0.4 MPa and 0.5 MPa, the tip displacement of the trailing-edge is 3 mm and 5 mm, respectively. The lift of aerofoil with flexible trailing-edge increases by 87% at AOA of 5°.

Analysis on pivot turning of quadruped robot with bionic flexible body driven by the PAMs

The pivot turning function of quadruped bionic robots can improve their mobility in unstructured environment.A kind of bionic flexible body mechanism for quadruped robot was proposed in this paper,which is composed of one bionic spine and four pneumatic artificial muscles(PAMs).The coordinated movement of the bionic flexible body and the leg mechanism can achieve pivot turning gait.First,the pivot turning gait planning of quadruped robot was analyzed,and the coordinated movement sequence chart of pivot turning was presented.Then the kinematics modeling of leg side swing and body bending for pivot turning was derived,which should meet the condition of the coordinated movement between bionic flexible body and leg mechanism.The PAM experiment was conducted to analyze its contraction characteristic.The study on pivot turning of the quadruped robot will lay a theoretical foundation for the further research on dynamic walking stability of the quadruped robot in unstructured environment.

Development of Flexible Spherical Actuator with 3D Coordinate Measuring Device

Rehabilitation devices help to recover the physical abilities of patients. This study aims to develop a portable rehabilitation device that is safe to use when?patients are holding it by hands. In a previous study, to realize a home rehabilitation device, a flexible spherical actuator that can provide motion to patients was developed. In this study, to measure the relative position between both handling stages, a 3D coordinate measuring device using three wire-type linear potentiometers and an embedded controller was proposed and tested. In this paper, the spherical actuator with built-in 3D coordinate measuring device is described. The measuring method and experimental results obtained are also presented. The tracking position control of the actuator using the measuring device was carried out. As a result, the position of the handling stages can be successfully controlled using the feedback signal from the tested?measuring device.

A protein-enabled protective film with functions of self-adapting and anion-anchoring for stabilizing lithium-metal batteries

Practical implementations of rechargeable lithium(Li)metal batteries have long been plagued by multiple problems of Li anode,such as Li dendrite growth,large volume change,low Coulombic efficiency.Here,we report a protein-enabled film that can provide effective protection for Li metal.The protective film with an integrated design of high flexibility,strong adhesion and high Li-ion transference number(0.80)is fabricated by incorporating denatured zein(corn protein)with polyethylene oxide(PEO)acting as an age nt for sustaining the denatured protein chains against refolding via the intermolecular interactions between them.Thus,a conformable zein-enabled protective film(zein@PEO)with simultaneous en hancement in flexibility,modulus and adhesion strength is gen erated to offer both functi ons of self-adapting and anion-anchoring abilities.The results show that the zein@PEO film is able to accommodate the volume change,reduce the side reactions,and homogenize the ion deposition.Benefiting from these significant properties/fu nctions,the Li/Cu cell with the zein@PEO film delivers prolonged cycle life for over 500 hours with stable performance.Paired with LiMn_(2)O_(4) cathode,the capacity,cycle stability and rate performance of the cell are remarkably improved as well,demonstrati ng the effectiveness in stabilizing Li metal batteries.

Design and Experiments of an Origami-Inspired Pneumatic Flexible Manipulator

Unlike traditional manipulators with high rigidity and limited degrees of freedom,pneumatic manipulators have significant superiorities such as flexibility,lightweight and cleanliness,and therefore,have been one of the most popular research directions in robotics.However,most existing pneumatic manipulators have disadvantages such as low rigidity and simple functionality.In order to make up for the shortcomings of existing pneumatic manipulators,this paper proposes a new pneumatic flexible manipulator inspired by the concept of origami,which realizes the combination and balance of flexibility and rigidity.Finite element analysis is conducted to study influences of the number of airbags,the angle of main beam,and the width of main beam on the performance of the flexible manipulator.The simulation results are utilized to optimize the structure of the flexible manipulator.A pneumatic control system is designed to realize the automatic control of the pneumatic flexible manipulator.At the same time,a prototype is 3D printed,the experimental platform for pneumatic deformation is built,and the verification experiments of the single-jaw manipulator and the three-jaw manipulator are completed.

基于热缩材料的气动柔性机器人转向机构设计

气动柔性机器人具有质量轻、环境适应性强、无需元件驱动、在恶劣条件下拥有较好的可靠性等优点。然而,转向运动控制一直是气动柔性机器人开发的最大难题并制约其大规模应用。针对此问题,设计一种通过电控加热使得热收缩膜实现主动转向的充气臂式柔性机器人,对其端部执行机构进行建模设计,对充气壁材料和热缩膜材料进行了实验选择;在此基础上,构建热致收缩的转向控制数学模型,搭建实验样机,并对转向效果进行验证。得到结论如下:充气壁带膜选择0.08 mm厚的PE筒膜,热缩膜选取厚度0.075 mm、宽度20 mm的PVC热缩膜,最佳的热缩温度为80℃。通过脉冲控制,实现了直角转向。该柔性机器人在管道检测方面具有良好的应用潜力。

基于SAC算法的含柔性负荷电-气互联系统的频率与气压协调控制策略

现今,电燃气系统在维持微电网稳定、经济、灵活运行方面发挥着重要作用。当其受到电力与天然气负荷扰动时,控制器需要协调微电网频率和天然气管道节点的燃气压力。为此,提出1种基于柔性动作评价(SAC)算法的电-气互联系统的频率-气压协调控制策略。首先,在分析天然气管网及耦合设备运行特性的基础上,建立天然气输送动态模型。其次,基于可控负荷用户行为的随机性,建立了包括微型燃气轮机(MT),电转气(P2G)设备、可控负荷、分布式电源和负荷的微电网负载频率控制模型。此外,根据微电网频率与气压2个控制目标,设计了控制器的结构。最后,设置不同工况进行仿真,结果表明所提策略能协调系统的频率与气压。

考虑偏差的刚柔耦合夹具气动机械手加载状态主动控制技术

当前刚柔耦合夹具气动机械手在夹取重量较大或形状复杂的工件时,加载状态会出现非线性震荡,造成控制偏差,降低控制平稳度。为了提升刚柔耦合夹具气动机械手加载状态主动控制效果,设计一种考虑偏差的刚柔耦合夹具气动机械手加载状态主动控制方法。考虑四种动界限情况计算刚柔耦合夹具气动机械手加载振荡;加载振荡下将偏差分为刚度偏差和柔度偏差,通过奇异函数和拉普拉斯变换计算等级刚度、挠度以及转角,获得气动机械手加载状态受力偏差;构建气动机械手和接杆的坐标系和运动坐标系,分析气动机械手终端位置矢量和驱动力矩的映射关联;通过PD反馈进行刚度偏差和柔度偏差补偿,完成加载状态主动控制。实验结果表明:该方法偏差补偿后,输出力矩更接近理想值,可准确计算刚柔耦合夹具气动机械手在加载状态中的挠度、回旋角度以及动态角度,使气动机械手加载状态主动控制更加平稳。

气动肌肉多关节柔性机械臂位姿控制

本文构建一个气动肌肉柔性机械臂的模型。首先建立刚性机械臂模型,并进行柔性化处理,然后设计机械臂关节角度传统PID控制器、机械臂关节角度比例微分控制器、基于模糊理论的机械臂关节角度PID控制器,以控制五个关节的角度最终实现机械臂末端位姿控制。仿真实验的结果表明,该模型的控制误差在0.3度以内,基本达到了设计要求。

基于PLC控制的煤矿识别卡自动装配产线设计

煤矿识别卡产品装配大部分采取人工工序分步骤装配的作业模式,在对现有的识别卡装配工艺进行调研后,总结出一套优化自动装配柔性工艺的措施,并基于此措施开发了一套基于PLC控制的识别卡自动装配产线平台,提升产品的生产效率,彻底解决识别卡产线装配产量不足的问题,极大提升煤矿产品的交付能力。通过分析煤矿识别卡产品自动装配产线平台的来料工装方案,研制了一种识别卡产品自动装配产线平台装置,提出了装配产线机械臂和气动组件装置代替或尽量减少人工作业的装配模式。通过PLC多融合自动控制的技术手段,增加了装配过程环节各工序的视觉检验过程,形成了识别卡产品自动装配产线平台和实际自动装配应用场景。

气动柔性扭转关节静态模型

基于气动柔性驱动器(Flexible pneumatic actuator,FPA)研制一种气动柔性扭转关节,该关节主要由两个弧形的FPA组成,向这两个FPA充入压缩气体,关节转过一定的角度。分析扭转关节中FPA壁厚变化规律,对单个FPA的自由端进行力矩平衡分析,建立该关节的静态模型,构建试验系统对气动柔性扭转关节进行压力转角关系试验。试验结果与仿真曲线存在一定误差,分析影响扭转关节静态模型准确性的因素,并根据试验结果对扭转关节的数学模型进行修正,得到的修正模型能够较好地描述关节的充气过程和放气过程。

气动柔性五自由度手指运动分析及控制

基于气动柔性驱动器,设计了气动柔性五自由度手指,并介绍了其结构原理。分析建立了五自由度手指的运动学方程,并采用遗传算法解决了该五自由度手指逆运动学中的冗余解问题。基于神经网络设计了手指控制器,并进行了手指指尖轨迹跟踪实验。实验结果表明,手指指尖的运动实验曲线与理论曲线比较接近,说明采用遗传算法及神经网络控制能够实现对五自由度手指的较精确实时控制。

气动柔性球关节的模糊PID控制

介绍了新型气动柔性球关节,讨论了其控制方法。综合模糊控制和 PID控制的特点,设计了针对气动柔性球关节的模糊 PID控制器,实现对球关节弯曲角度、偏转方向等系统参数的动态控制。实验结果表明,模糊 PID 控制可以实时准确地对气动柔性球关节进行控制,设计的控制系统可以作为气动柔性球关节的有效控制系统,用于进行相关研究。

基于气动柔性驱动器的球果采摘末端抓持器

为实现球果的安全、可靠采摘,基于气动柔性驱动器(FPA)设计了球果采摘末端执行器,主要由3个FPA驱动的手指和基座构成。建立了手指指端在基座坐标系内的运动学方程,分析了末端抓持器在任意姿态下进行球果抓握的力学过程,建立了球果抓持数学模型。实验结果表明,所设计的球果采摘末端执行器可对成熟球果进行任意姿态的抓握,建立的数学模型可用于实际的采摘过程控制。

基于气动柔性驱动器的苹果采摘末端执行器研究

设计了一种基于气动柔性驱动器的苹果采摘末端执行器:以气动柔性驱动器作为其弯曲关节,用力学分析的方法对弯曲关节及末端执行器进行建模,分析建立关节弯曲量及输出力与其内腔气体压力之间的数学关系;建立了末端执行器抓取苹果目标的数学模型。实验结果表明:该末端执行器有较大的输出力,能很好地抓持苹果,并具有很好的柔顺性。

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 。