变时延力反馈遥操作机器人系统的内模控制

针对遥操作机器人通讯信道变化时延破坏系统稳定性和透明性的问题,为力反馈遥操作系统建立了内模控制结构,设计了两端控制器,并给出了有界时延摄动下系统鲁棒稳定和满足鲁棒性能准则的控制器参数范围,使系统在变时延下依然稳定并具有良好的透明性．给出的控制方法不仅对时延状况适应性强,而且控制器参数少,相关度低,依据不同性能要求进行选取的灵活性大．     

A control scheme for stable force-reflecting teleoperation over IP networks.

The problem of force-reflecting teleoperation over Internet protocol networks is addressed. The existence of time-varying communication delay and the possibility of data losses are taken into consideration. Since significant data loss may result in discontinuity of the reference trajectory transmitted through the communication channel, the proposed control scheme includes a filter that provides a smooth approximation of a possibly discontinuous reference trajectory. The stability of the overall system is guaranteed by a version of the input-to-output stable small-gain theorem for functional differential equations. If the communication delay in the forward channel is an "approximately smooth" function of time, the proposed scheme guarantees that the slave manipulator tracks the delayed trajectory of the master within a prescribed small error.     

A small gain framework for networked cooperative force-reflecting teleoperation

For cooperative force-reflecting teleoperation over networks, conventional passivity-based approaches have limited applicability due to nonpassive slave–slave interactions and irregular communication delays imposed by networks. In this paper, a small gain framework for stability analysis design of cooperative network-based force reflecting teleoperator systems is developed. The framework is based on a version of weak input-to-output practical stability (WIOPS) nonlinear small gain theorem that is applicable to stability analysis of large-scale network-based interconnections. Based on this result, we design a cooperative force-reflecting teleoperator system which is guaranteed to be stable in the presence of multiple network-induced communication constraints by appropriate adjustment of local control gains and/or force-reflection gains. Experimental results are presented that confirm the validity of the proposed approach.     

并联机床控制器的设计与研究

根据并联机床的插补算法结合计算机控制技术提出了并联机床数控系统专用控制器的总体结构,并控对控制器的软、硬件结构进行了研究和设计.在控制器的硬件结构上,采用了多CPU结构,合理分配了数控运行中的任务,从而间接提高了系统运行效率.     

异构遥操作仿人机械臂灵巧作业控制

针对异构遥操作系统在作业过程中,从端机器人控制灵活性受限的问题,提出了一种基于主从工作空间与速度的双模比例映射控制方法.限定主从端的操作空间,并采用比例度映射的方式实现主端对从端运动控制.采用Phantom Omni力反馈设备与Kinova仿人机械臂分别作为遥操作系统的操作主端和工作从端,构建了双边控制系统及实物抓取实验,结果表明:在映射的工作空间内,主端能够有效完成对从端的运动控制;在实物抓取实验过程中,主端能够有效对从端实现作业控制.所设计的系统满足控制精度需求,操作灵活.     

并联机器人的非线性 P I D 控制

采用分散控制策略和非线性PID控制算法，实现6自由度并联机器人的商精度轨迹最踪控制。该非线性PID控制器由两个二阶非线性微分最踪器提供高质量的微分信号，并采用非线性组合形成控制作用，从而确保了高控制性能的实现。实验结果验证了非线性控制方案的有效性。     

Physiological hemostasis based intelligent integrated cooperative controller for precise fault-tolerant control of redundant parallel manipulator

This paper focuses on precise fault-tolerant control for actual redundant parallel manipulator. Based on kinematic redundancy, some unnoticed influences such as mechanical clearance have been considered to design a more precise and intelligent fault-tolerant plan for actual plants. According to regulation principles in human hemostasis system, a bio-inspired intelligent integrated cooperative controller (BIICC) is developed including system structure, algorithm and step in parameter tuning. The proposed BIICC optimises partial error signal and improves control performance in each sub-channel. Moreover, the new controller transfers and disposes cooperative control signals among different sub-channels to achieve an intelligent integrated fault-tolerant system. The proposed BIICC is applied to an actual 2-DOF (degrees of freedom) redundant parallel manipulator where the feasibility of the new controller is demonstrated. The BIICC is beneficial to control precision and fault-tolerant capability of redundant plant. The improvements are more obvious in cases where extra actuators of redundant manipulator are broken.     

Kinematics analysis and statics of a 2SPS+UPR parallel manipulator

In this paper, the kinematics and statics of a 2SPS+UPR parallel manipulator are studied systematically. First, its simulation mechanism is created, and formulae for solving the inverse/forward displacement kinematics are derived. Second, formulae for solving inverse/forward velocity and active/constrained forces are derived. Third, formulae for solving inverse/forward acceleration are derived, and a workspace is analysed. The analytic results are verified by its simulation mechanism. The authors would like to acknowledge the financial support of the Natural Sciences Foundation Council of China (NSFC) 50575198 and of Doctoral Fund from National Education Ministry of China No. 20060216006.     

Bilateral parallel force/position teleoperation control

The extension of parallel force/position control to teleoperation systems is considered in this article. In the proposed four‐channel bilateral controller, higher priority is granted to position control at the master side and to force control at the slave side. The primary goal of this control architecture is the enhancement of force and position tracking performance in the presence of uncertainties in the system and environment. The stability and performance of the proposed controller is investigated by analyzing the three decoupled single‐degree‐of‐freedom systems obtained from decoupling and projecting the closed‐loop system dynamics onto the slave task‐space orthogonal directions. Experimental results demonstrate significant improvement in transparency. © 2002 Wiley Periodicals, Inc.     

Development of human-machine interface for teleoperation of a mobile manipulator

Human-robot control interfaces have received increased attention during the past decades for conveniently introducing robot into human daily life. In this paper, a novel Human-machine Interface (HMI) is developed, which contains two components. One is based on the surface electromyography (sEMG) signal, which is from the human upper limb, and the other is based on the Microsoft Kinect sensor. The proposed interface allows the user to control in real time a mobile humanoid robot arm in 3-D space, through upper limb motion estimation by sEMG recordings and Microsoft Kinect sensor. The effectiveness of the method is verified by experiments, including random arm motions in the 3-D space with variable hand speed profiles.     

Robust tracking control design for a 6 DOF parallel manipulator

The focus of this work is on a robust tracking control design for a 6 DOF parallel manipulator in the presence of nonlinearity and fast (or slowly) time‐varying uncertainty. Two types of controllers are presented. The controls are based on the Lyapunov approach and guarantee a practical stability. The controls utilize the information of link displacements and its velocities. The first control scheme uses the quadratic Lyapunov function and other uses the geometry dependent Lyapunov function, which excludes the inverse matrix computation on the inertia matrix. Also, the hydraulic dynamics is considered in the control design and control performance. The control performances of the proposed algorithms are verified by simulations and experiments. © 2000 John Wiley & Sons, Inc.     

Kinematics analysis of an offset 3-UPU translational parallel robotic manipulator

The parallel robotic manipulator has attracted many researchers’ attention and it also has growing applications to different areas. This paper proposes a 3-UPU (universal–prismatic–universal) translational parallel robotic manipulator with an equal offset in its six universal joints, based on the zero offset 3-UPU parallel manipulator. The kinematics of the new manipulator is analyzed and its inverse and forward kinematics solutions are provided. The conclusion is that its forward kinematics has 16 solutions instead of two in the zero offset manipulator.     

Adaptive control scheme for a robot manipulator: direct decoupler and PID controller

A two level adaptive controller for the control of a high speed robot is proposed. Dynamic interaction effects of the robot system are eliminated by applying a centralized adaptive multivariable decoupler. Decentralized adaptive PID controllers stabilize and eliminate the static positioning errors of the robot system. No prior knowledge of robot dynamics is required for this scheme. Output transients caused by sensitivity to the system parameter variations is reducible by adjusting the gain constants of the decoupler. Computation load for the implementation of the decoupler is minimal due to its direct nature, The effectiveness of the scheme is demonstrated by simulation results in high speed repetitive motion trackings and load change conditions.     

Observer-based backstepping control of a 6-dof parallel hydraulic manipulator

In this paper, a backstepping control strategy is proposed to control the 6-dof parallel hydraulic manipulator (Stewart platform) while incorporating an observer-based forward kinematics solver. Different from conventional control methods, the proposed control considers not only the platform dynamics but also the dynamics of the hydraulic actuator. One feature of this work is employing the observer-based forward kinematics solution to achieve the posture tracking goal successfully only with the measurement of actuators lengths. When designing the controller of hydraulic actuators, the friction compensation is applied to improve the performance. The stability of the whole system is thoroughly proved to ensure convergence of the control errors. Simulations and experimental results are presented to validate the hereby proposed results.     

Kinematics for the whole arm of a serial-chain manipulator

This paper provides a viewpoint for kinematics for the whole arm of a serial-chain manipulator with 2-d.o.f. rotational joints. An in-depth understanding of the duality between a rigid link and a 2-d.o.f. joint allows us to derive simple and geometric equations describing the manipulator kinematics. The obtained kinematic equations are analyzed in two ways compared with the Frenet-Serret formula of a spatial curve which is utilized for a reference shape of the manipulator. One way is based on limit analysis where we increase the number of joints while the total length of the manipulator remains constant. The other way utilizes an extended mechanism through the link-joint duality. The information presented in this paper is useful for mechanism design dynamic analysis, control design and motion planning of the manipulators in whole-arm manipulation.     

Time forward observer based adaptive controller for a teleoperation system

This paper presents a design of a teleoperation system using time forward observer-based adaptive controller. The controller is robust to the time-variant delays and the environmental uncertainties while assuring the stability and the transparent performance. A novel theoretical framework and algorithms for this teleoperation system have been built up with neural network-based multiple model control and time forward state observer. Conditions for stability and transparency performance are also investigated.     

Design,analysis and control of a winding hybrid-driven cable parallel manipulator

This paper is related to the design, analysis and control of a winding hybrid-driven cable parallel manipulator (WHCPM). The WHCPM has the advantages of both cable parallel manipulator and hybrid-driven planar five-bar mechanism. Design of the WHCPM is explained, and the structure static analysis is carried out by using finite element method. Dynamics and payload capability of the WHCPM are studied. The WHCPM prototype is built for precision tracking experiments. To evaluate the manipulator design, the dynamic control compensation is performed on the basis of the conventional PID controller and the adaptive fuzzy sliding mode controller. The simulated and experimental results are reported and the tracking performance of the WHCPM is significantly improved by applying the proposed control technique in comparison with the performance when applying the conventional PID controller.     

Robustness analysis of a pd controller with approximate gravity compensation for robot manipulator control

Asymptotically stable robot manipulator control in both joint space and Cartesian space can be achieved by using a PD controller with gravity torque compensation. However, the stability of this class of control law has not been analyzed with the use of estimated gravity torques. The objective of this article is to present such a stability proof assuming uncertainty in the gravity estimate. The proof is carried out for the Cartesian space controller. The result is supported by computer simulation. © 1994 John Wiley & Sons, Inc.     

基于止血机制的冗余并联机器人精准容错控制

冗余并联机器人具有冗余容错能力,能在局部故障的情况下继续工作.而设备的机械间隙无法完全避免,并且较难建立精准的机械间隙模型,因此基于运动学冗余的常规容错方法较难实现精准容错控制.基于生理止血调控机制,考虑冗余并联机器人控制特性和机械间隙因素,提出一种新颖的精准容错控制器.与止血机制类似,该控制器不但能够进行子通道误差优化,而且能进行全局故障辨识和容错补偿.利用2-DOF冗余并联机器人进行了真实实验.结果表明,提出的精准容错控制器的控制精度和容错能力均比传统控制器有较大提高.