基于自适应阻抗控制的大负载液压机械臂柔顺控制

针对大负载液压机械臂的柔顺作业问题,提出了一种自适应阻抗控制算法进行机械臂柔顺控制。算法根据六维力传感器测量的接触力信息和机械臂末端位置信息,对环境刚度和环境位置实时估计。根据环境刚度和环境位置的估计值,对机械臂的参考轨迹进行修正,实现自适应阻抗控制,以达到更佳的力控效果。开展了液压机械臂管道搬运实验,进行自适应控制算法性能验证。结果表明,相较于传统的阻抗控制算法,机械臂采用自适应阻抗控制算法能够获得更好的力控性和柔顺性。     

机器人自适应模糊阻抗控制方法

针对机械臂在未知环境或环境参数存在变化的情况下无法有效跟踪目标接触力,提出一种在线调节参考轨迹自适应阻抗控制算法,该方法能够实现精确力控制,并保证机械臂系统的运动稳定。根据力误差信息调整参考轨迹以实现力跟踪。同时引入模糊调整器实时调整控制算法参数,优化机械臂运动性能。以RRR型三自由度机械臂为例对算法进行仿真验证。仿真结果表明,该方法提高了力控制精度与动态响应,其自适应算法有效增强了机械臂在与外界环境接触时对接触环境参数变换的鲁棒性。     

机械臂轨迹的阻抗滑膜控制

针对机械臂在接触操作物时进行移动时位置会产生偏差,导致两者之间会有作用力,该作用力将会对操作的物体产生破坏。所以先对机械臂采用滑膜控制,去控制机械臂更好的跟随路径。但是由于滑膜控制会产生抖振,所以改变滑膜控制的切换函数,减弱控制系统的抖振。在此基础上考虑机械臂末端位置的偏差,将阻抗控制和改进后的滑膜控制结合,减少滑膜控制中的抖振,控制机械臂末端力的接触力在合适范围之内,同时要让机械臂能够很好的跟踪预定曲线。仿真结果表明,双曲正切为切换函数的滑膜控制,能更好的降低控制器的抖振,而且将改进的滑膜控制和阻抗控制可以更好的控制机械臂末端的压力,同时机械臂末端也能将好的跟踪设定曲线。     

基于阻抗控制的飞机清洗臂主动柔顺控制研究

针对飞机清洗臂清洗飞机蒙皮过程中的接触力控制问题,提出了基于位置的模糊自适应阻抗控制策略,开展了相关的理论分析和仿真验证研究。在阻抗控制的基础上引入自适应控制,解决了传统阻抗控制难以精确跟踪位置的问题。同时,加入模糊控制器,通过力误差实时调节阻抗参数,提高位置跟踪的准确性和稳定性。搭建MATLAB仿真平台,仿真结果表明,该方法可以准确地实现对清洗臂末端的位置控制,提高了清洗臂的跟踪效果。     

基于变参数阻抗控制的机器人恒力打磨研究

面向机器人恒力打磨需求,文章设计了阻抗参数在线调整与离线优化的自适应阻抗控制算法,实现了打磨力控制。自适应阻抗控制算法将刚度参数作为时变参数,根据打磨接触力实时在线调整,以消除打磨过程中的稳态误差。针对阻尼参数和惯性参数难以整定的问题,以降低系统超调量和调整时间作为优化目标,采用改进粒子群算法进行阻抗参数离线优化。进行了机器人恒力打磨仿真,仿真结果表明,该方法可以综合改善机器人的恒力控制性能。开展了机器人恒力打磨实验,实验结果表明,该方法可以有效地提高机器人打磨表面质量。     

具有接触力感知反馈的2R机械臂设计与控制

针对高端制造过程中机械臂与工件之间应具有接触力感知与控制要求的问题,设计一种具有接触力感知反馈的2R 机械臂(a 2R manipulator with contact force perception feedback,2RM-CFPF).首先,利用堆叠式压电陶瓷传感器设计一种具有接触力感知反馈的机械臂关节,建立关节3D模型并阐述关节结构.然后,基于所设计的关节搭建2RM-CFPF机械臂模型,探究其工作机理并推导出数学模型;结合2RM-CFPF机械臂自身特性,采用基于阻抗滑模控制的运动位置/接触力控制方法,实现2RM-CFPF机械臂的力-位混合控制.最后,进行2RM-CFPF机械臂运动控制仿真实验,仿真实验结果表明阻抗滑模控制法能够有效实现2RM-CFPF机械臂的力-位混合控制,满足高端制造中的接触力感知控制要求.     

冗余空间机械臂的运动学和笛卡尔阻抗控制方法

为了能让七自由度空间机械臂在空间站外壁换位行走,需要在对接的过程中能够自动控制机械臂接触力以确保其在安全的范围之内。介绍了七自由度空间机械臂的运动学计算方法,采用二次计算法求得其逆运动学解。提出了基于安装在空间机械臂末端六维力传感器反馈的笛卡尔空间阻抗控制方法,将逆运动学解转化到关节空间的位置内环进行位置控制,经Simulink仿真优化参数后在空间机械臂上进行了调试实验,结果表明,力的控制效果柔顺。     

基于改进自适应算法的机械臂位置/力控制研究

传统机械臂末端与环境接触时对位置和接触力单独控制,造成控制不精确,收敛时间较长,针对这一问题,提出一种改进自适应控制策略。首先,考虑了实际存在的环境刚度,对机械臂系统从关节空间到笛卡尔空间进行坐标变换,将两个控制信号整合到同一坐标下;其次,在同一笛卡尔空间下,将坐标分为切向位置空间和法向接触力空间,实现由控制位置和力两个物理量到控制一个轨迹物理量的简化;然后,在改进自适应算法的自适应律中引入参数误差,设计动力学控制器修正机械臂参数,并利用Lyapunov理论证明了闭环系统稳定性;最后,经过仿真验证,不仅在位置跟踪和力控制方面缩短收敛时间,而且参数估计方面也能缩短收敛时间,提高收敛精度,说明了该方法的实用性和有效性。     

基于指令滤波的机械臂有限时间输出约束阻抗控制

提出一种基于指令滤波的机械臂有限时间输出约束阻抗控制方法.通过阻抗控制技术来解决机械臂与环境之间的相互作用,使机械臂跟踪期望轨迹.通过有限时间控制提高机械臂控制的响应速度,缩小跟踪误差,并引入障碍Lyapunov函数对机械臂末端输出状态进行约束.采用模糊自适应技术处理机械臂系统中的未知摩擦量和外部扰动量.仿真结果表明:该方法实现了对期望轨迹的有效跟踪控制,并且使机械臂输出状态都限制在预定义的约束空间中,具有更快的响应速度和更好的跟踪效果.     

面向清洗作业的车载机械臂柔顺控制研究

长行程机械臂在清洗作业中要求末端与清洗表面之间的接触力受到约束,以防止被清洗表面受到损害。针对这一问题,提出了一种基于位置的柔顺控制策略,引入清洗机械臂末端力矩信息,构造了一种在离线轨迹规划基础上的实时阻抗修正方法,从而有效改善了清洗过程中的接触力控制效果。     

A double-loop structure in the adaptive generalized predictive control algorithm for control of robot end-point contact force

Robot force control is an essential issue in robotic intelligence. There is much high uncertainty when robot end-effector contacts with the environment. Because of the environment stiffness effects on the system of the robot end-effector contact with environment, the adaptive generalized predictive control algorithm based on quantitative feedback theory is designed for robot end-point contact force system. The controller of the internal loop is designed on the foundation of QFT to control the uncertainty of the system. An adaptive GPC algorithm is used to design external loop controller to improve the performance and the robustness of the system. Two closed loops used in the design approach realize the system?s performance and improve the robustness. The simulation results show that the algorithm of the robot end-effector contacting force control system is effective.     

力控法兰的模糊PID恒力控制方法

针对工业机器人进行接触式作业过程中对末端接触力的要求,提出了一种基于力控法兰的末端恒力控制方法。对力控法兰进行了分析建模与参数辨识,设计了模糊控制与比例积分微分(proportion integral derivative,简称PID)控制并行的模糊PID控制器,通过Matlab仿真对纯模糊控制与模糊PID控制效果进行了对比,并研究了模糊PID控制器各参数对控制性能的影响。最后,搭建了基于Labview和外部设备互连(peripheral component interconnect,简称PCI)总线数据采集卡的实验平台,对力控法兰末端输出力进行了实验验证。仿真结果表明,纯模糊控制可提高系统响应性能,但存在一定的稳态误差。加入PID控制与模糊控制并行控制后,仿真与实验证明,阶跃响应的稳态误差消除,正弦跟随效果明显改善,恒力控制输出力在期望力F=10N时波动误差为±0.8N。因此,通过模糊PID控制可实现力控法兰末端的恒力控制,具有较好的动态响应性和跟随鲁棒性。     

数控凸轮磨床磨削力的模糊适应控制研究

以数控凸轮磨床的磨削过程为研究对象,建立了凸轮磨削过程的磨削力数学模型,研究了磨削力的间接检测和控制方法,并在此基础上提出一种基于模糊策略的适应控制方法对凸轮磨削过程的磨削力给予控制,采用MATALAB进行了控制器的设计和磨削加工的仿真验证,结果表明该方法能有效地解决凸轮磨削过程中的磨削力的波动问题,控制器具有良好的动态特性,实现了磨削过程中的最优金属切除率的目的,提高了凸轮磨削的表面质量。     

未知环境下柔性二连杆机械臂的自适应阻抗控制

针对机器人与环境接触作业的需求,基于假设模态法建立了刚柔耦合动力学模型,并考虑环境参数不精确干扰,设计了自适应阻抗控制器,分析了其稳定条件。在MATLAB/Simulink中搭建了可对柔性机械臂进行自适应阻抗控制的仿真平台,计算了平面内二连杆柔性机械臂在含有三角形凹陷环境表面的接触运动和柔性变形模态。对比分析了刚性和柔性机械臂位控和力控效果及自适应项对控制响应的影响。基于Staubli机器人展开了实验。结果表明：柔性变形会使得机械臂的位控和力控效果变差;自适应阻抗控制会改善控制响应,对环境不确定具有鲁棒性。设计的自适应阻抗控制可实现柔性机械臂在不规则表面的稳定接触和运动。     

Composite adaptive control of belt polishing force for aero-engine blade

The existing methods for blade polishing mainly focus on robot polishing and manual grinding.Due to the difficulty in high-precision control of the polishing force,the blade surface precision is very low in robot polishing,in particular,quality of the inlet and exhaust edges can not satisfy the processing requirements.Manual grinding has low efficiency,high labor intensity and unstable processing quality,moreover,the polished surface is vulnerable to burn,and the surface precision and integrity are difficult to ensure.In order to further improve the profile accuracy and surface quality,a pneumatic flexible polishing force-exerting mechanism is designed and a dual-mode switching composite adaptive control(DSCAC) strategy is proposed,which combines Bang-Bang control and model reference adaptive control based on fuzzy neural network(MRACFNN) together.By the mode decision-making mechanism,Bang-Bang control is used to track the control command signal quickly when the actual polishing force is far away from the target value,and MRACFNN is utilized in smaller error ranges to improve the system robustness and control precision.Based on the mathematical model of the force-exerting mechanism,simulation analysis is implemented on DSCAC.Simulation results show that the output polishing force can better track the given signal.Finally,the blade polishing experiments are carried out on the designed polishing equipment.Experimental results show that DSCAC can effectively mitigate the influence of gas compressibility,valve dead-time effect,valve nonlinear flow,cylinder friction,measurement noise and other interference on the control precision of polishing force,which has high control precision,strong robustness,strong anti-interference ability and other advantages compared with MRACFNN.The proposed research achieves high-precision control of the polishing force,effectively improves the blade machining precision and surface consistency,and significantly reduces the surface roughness.     

Simultaneous control of robot manipulator impedance and generalized force and position

Certain industrial tasks require forces to be applied to objects during task execution. Of these tasks, a subset of them may be completed successfully with only crude control over contact force. A open-loop method of force control is proposed for these applications. This method utilizes the impedance control of Hogan to achieve open-loop control over generalized contact forces and position. The net result is simultaneous control of manipulator mechanical impedance and the generalized position and the force of the robot. An algorithm is proposed which determines the manipulator generalized position inputs, the only signal available to an impedance controller, in order to generate prescribed generalized forces while in contact with fixed objects. A new approach to the establishment of the stability of impedance controls during object contact is given, utilizing the theory of singularly perturbed dynamic systems. Experimental results on a two degree-of-freedom robot confirms the validity of the approach proposed here to control contact forces in an open-loop manner.     

机器人柔顺力控装置研究

机器人自动化抛光过程中,工具与工件间的接触力控制尤为重要.基于主动柔顺控制的原理,提出了面向工业机器人的柔顺力控装置及控制方法.进行了系统的结构设计和动力学建模,基于BP神经网络PID算法,设计了该柔顺力控装置的自适应控制策略.最后进行力控跟踪实验,实验结果表明,柔顺力控装置能够保证打磨过程中工件与工具之间的接触力恒定...     

基于模糊自整定PD控制器的机器人计算力矩控制

设计了应用于计算力矩控制方案中的模糊PD控制器(FLC),进一步提出了模糊自整定PD控制器(SFLC).用带有末端执行器的平面3自由度机器人为例进行了动力学仿真,并将采用固定PD控制器、模糊PD控制器和模糊自整定PD控制器的计算力矩控制方案进行了比较.仿真结果表明,采用模糊自整定PD控制器(SFLC)后能有效的克服模型不确定所造成的影响,得到比较小的轨迹跟踪误差,为机器人的实际控制提供了理论基础.     

On position/force tracking control problem of cooperative robot manipulators using adaptive fuzzy backstepping approach

In this paper, the position and force tracking control problem of cooperative robot manipulator system handling a common rigid object with unknown dynamical models and unknown external disturbances is investigated. The universal approximation properties of fuzzy logic systems are employed to estimate the unknown system dynamics. On the other hand, by defining new state variables based on the integral and differential of position and orientation errors of the grasped object, the error system of coordinated robot manipulators is constructed. Subsequently by defining the appropriate change of coordinates and using the backstepping design strategy, an adaptive fuzzy backstepping position tracking control scheme is proposed for multi-robot manipulator systems. By utilizing the properties of internal forces, extra terms are also added to the control signals to consider the force tracking problem. Moreover, it is shown that the proposed adaptive fuzzy backstepping position/force control approach ensures all the signals of the closed loop system uniformly ultimately bounded and tracking errors of both positions and forces can converge to small desired values by proper selection of the design parameters. Finally, the theoretic achievements are tested on the two three-link planar robot manipulators cooperatively handling a common object to illustrate the effectiveness of the proposed approach.     

Fuzzy force control of constrained robot manipulators based on impedance model in an unknown environment

To precisely implement the force control of robot manipulators in an unknown environment, a control strategy based on fuzzy prediction of the reference trajectory in the impedance model is developed. The force tracking experiments are executed in an open-architecture control system with different tracking velocities, different desired forces, different contact stiffnesses and different surface figurations. The corresponding force control results are compared and analyzed. The influences of unknown parameters of the environment on the contact force are analyzed based on experimental data, and the tunings of predictive scale factors are illustrated. The experimental results show that the desired trajectory in the impedance model is predicted exactly and rapidly in the cases that the contact surface is unknown, the contact stiffness changes, and the fuzzy force control algorithm has high adaptability to the unknown environment. Translated from Journal of Northeastern University (Natural Science), 2005, 26(8): 766–769 [译自: 东北大学学报 (自然科学版)]