主从遥操作位置-速度混合映射研究

主从异构型遥操作机器人系统在主从结构、自由度等方面的差异,导致其主端小范围操作空间难以覆盖从端大范围工作空间,以及从端难以精确定位。针对此问题,首先搭建了一套主从异构型遥操作机器人系统的软硬件平台,然后对主从端机器人进行运动学建模,进而提出了一种主端位置-从端速度和主端位置-从端位置混合切换的映射算法。一方面,所提算法通过主端位置-从端速度映射模式解决主从工作空间不匹配的问题,从而提高大范围空间下从端抵近目标的效率;另一方面,所提算法通过主端位置-从端位置映射模式实现从端精细定位,同时克服主端位置-从端速度映射中从端无法快速换向运动的缺陷。实验结果表明,所提混合映射算法能够实现主端遥操作从端机器人高效地完成复杂、精细的操作任务。     

外骨骼式遥操作主手设计及主从异构映射算法研究

为了更好地促进机器人适应复杂的遥操作任务,开发了能够精确获取人体上肢运动信息的外骨骼式遥操作主手,并通过异构映射算法,实现对6自由度协作机械臂的遥操作．首先,基于人体仿生结构,设计了可穿戴式8自由度外骨骼主手（臂部7自由度和手部1自由度）;其次,通过改进的D-H（Denavit-Hartenberg）方法建立遥操作系统的运动学模型,基于Matlab的机器人工具箱进行了工作空间仿真,并设计主从异构映射算法;最后,实验验证外骨骼主手在遥操作系统中的可操作性,以及工作空间异构映射算法的可行性．实验表明,外骨骼主手能够控制从端机械手臂,且保证末端位置和姿态一致,可在大范围工作空间内复现人体上肢精细运动,主从跟随误差达2 mm,工作空间类似于直径1.08 m的半球形．因此,可穿戴式的外骨骼主手使操作者能更加直观地参与到遥操作系统当中,辅助操作者更加高效地完成精细复杂任务．     

主从遥操作下双臂机器人的阻抗控制策略研究

在遥操作机器人系统中,从端机器人不仅需准确地跟随主端设备的运动,还需与外界环境保持合适接触力,以避免因接触力过大对机器人和环境造成破坏.由于遥操作机器人系统中主从端设备是分离的,要实现遥操作下柔顺接触是极具挑战的.为了提高遥操作机器人系统任务执行的安全性,本文结合运动映射提出一种主从遥操作下阻抗控制策略.首先,通过提出主从端运动映射策略,将主从端设备联系起来,并获得从端机器人运动的目标位姿.接着,为了实现机器人末端执行器与环境的柔顺接触,提出阻抗控制策略,建立机器人与外界环境之间的位置和接触力的动态响应关系.同时,引入虚拟排斥力,让从端机器人的双臂在可行的空间中运动,从而提高了机器人操作的柔顺性和安全性.设计了机器人拖拽和白板擦拭两个实验来验证方法有效性.实验结果表明,所提出方法可实现机器人在具有接触的任务中的柔顺操作,可提高操作的安全性.     

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.     

基于模糊补偿的主从式上肢外骨骼康复机器人训练控制方法

针对主从式上肢外骨骼康复机器人主臂信息获取、从臂快速响应等问题,提出了基于关节位姿、速度和力/力矩等信息的运动意图建模方法及基于模糊补偿的康复训练控制策略.根据人体工程学原理,提出了一种同构同型的主从式双臂康复机器人新型结构;利用D-H算法给出了笛卡儿空间的主从臂运动学模型,建立了患者健肢运动意图信息和从臂各关节动作的人机协作映射关系;以患者运动意图力矩作为输入,基于模糊补偿算法提出了患者-主臂-从臂协作控制策略,并利用李亚普诺夫定理证明了该控制系统的稳定性.仿真结果表明,康复机器人从臂可以根据患者运动意图跟随主臂运动,能有效地防止抖动误动,可避免对患肢的二次伤害.实验结果表明从臂运动轨迹平滑,无剧烈波动,控制轨迹跟踪主臂效果好.     

具有主动约束的医疗机器人系统的主从控制

在分析了穿刺手术机器人系统功能需求的基础上,搭建了主从遥操作系统的半实物仿真平台。在主从控制的基础上,提出一个利用虚拟夹具VF(Virtual Fixture)算法结合Proxy的方法的主动约束控制策略。实验结果表明,系统能够在给定运动约束的情况下完成相应的主从控制。     

腹腔微创手术机器人的主从控制

为提高基于内窥镜的腹腔微创手术机器人系统的手眼协调一致性,提出了一种主从控制方法.基于旋量理论建立从手系统的正逆运动学模型,基于运动模型提出内窥镜坐标系下的主从运动控制算法,该算法包含了运动的一致性控制、相对运动控制和比例运动控制.主手的腕部为被动方式(无电机驱动),不能在任意位置保持静止,在手术开始、中途中断或调节主手工作空间时,主手和从手姿态不能保持一致.为此,开展3种辅助功能实现研究,分别为主从姿态配准、手术器械更换和主从二次映射.最后进行了套环和穿线实验,这两组实验最大空间位置误差均小于1 mm,说明该算法可有效地提高手眼协调的一致性.     

基于混合算法的空间机器人运动学参数辨识

外太空环境恶劣,空间遥操作机器人结构在太空环境作业时会产生形变,而且其加工生产也存在加工误差,空间遥机器人的形变引起DH参数的误差,为了完成空间机器人系统的地而仿真预测,并且确保空间遥操作机器人完成工作任务,必须根据遥测数据准确的辨识出空间机器人系统的运动学参数.提出了混合非线性参数辨识的LM(Levenberg-Marquarat)和递推最小二乘办法的混合辨识算法.最后,给出了办法的实例仿真,说明了辨识算法的稳定性,能够完成对空间遥操作机器人的运动学参数的辨识.     

面向手势动作捕捉的传感器设计及主从手运动映射

本文针对人手和机器人灵巧手在运动学上尺寸的不一致现象带来的主从手指尖运动空间映射的不一致性进行研究.基于聚氨酯拉伸应变传感器构建了测量手指关节弯曲角度的数据手套.通过建立主从手的运动学模型,基于旋转矩阵理论及正向运动学提出了一种指尖运动轨迹计算方法及手势动作捕捉算法.基于正向运动学及逆向运动学的指尖运动映射算法建立了主从手的指尖运动空间轮廓.建立虚拟实验场景,分别针对关节角度映射算法、手势动作捕捉算法及指尖运动映射算法进行了一系列试验.通过实验得出基于聚氨酯的拉伸应变传感器具有良好的时间响应特性及电学稳定性,基于手势动作捕捉算法能够获取主从手的指尖运动空间轮廓,指尖运动轨迹的计算误差控制在2.8 mm以内.结果证明了基于手势动作捕捉算法以及指尖运动映射算法能够实现主从手指尖运动空间的一致性.     

基于时域无源性控制的六足机器人双边触觉遥操作

随着六足机器人研究工作的深入,针对其遥操作系统的开发面临诸多挑战.为了弥补松软接触条件对系统可控性及稳定性的影响,提出一种基于时域无源性控制(time-domain passivity control,TDPC)的六足机器人双边触觉遥操作方法.其主从两端采取位置-速度的交互模式,通过分析足-地柔性接触的作用机理,构建无源观测器和无源控制律以补偿足底滑移所导致环境系统的潜在有源性,采用速度跟踪模式设计基于触觉力反馈的系统控制架构,并利用Llewellyn准则确定控制律参数的稳定范围.最后,搭建半物理仿真实验平台并验证所提出的双边触觉遥操作方法在松软地形条件下能够保证六足机器人遥操作系统的稳定,且兼具较好的持续跟踪能力.     

A Telepresence-Guaranteed Control Scheme for Teleoperation Applications of Transferring Weight-Unknown Objects

Currently, most teleoperation work is focusing on scenarios where slave robots interact with unknown environments. However, in some fields such as medical robots or rescue robots, the other typical teleoperation application is precise object transportation. Generally, the object’s weight is unknown yet essential for both accurate control of the slave robot and intuitive perception of the human operator. However, due to high cost and limited installation space, it is unreliable to employ a force sensor to directly measure the weight. Therefore, in this paper, a control scheme free of force sensor is proposed for teleoperation robots to transfer a weight-unknown object accurately. In this scheme, the workspace mapping between master and slave robot is firstly established, based on which, the operator can generate command trajectory on-line by operating the master robot. Then, a slave controller is designed to follow the master command closely and estimate the object’s weight rapidly, accurately and robust to unmodeled uncertainties. Finally, for the sake of telepresence, a master controller is designed to generate force feedback to reproduce the estimated weight of the object. In the end, comparative experiments show that the proposed scheme can achieve better control accuracy and telepresence, with accurate force feedback generated in only 500 ms.      

Enhanced teleoperation performance using hybrid control and virtual fixture

To develop secure, natural and effective teleoperation, the perception of the slave plays a key role for the interaction of a human operator with the environment. By sensing slave information, the human operator can choose the correct operation in a process during the human–robot interaction. This paper develops an integrated scheme based on a hybrid control and virtual fixture approach for the telerobot. The human operator can sense the slave interaction condition and adjust the master device via the surface electromyographic signal. This hybrid control method integrates the proportional-derivative control and the variable stiffness control, and involves the muscle activation at the same time. It is proposed to quantitatively analyse the human operator's control demand to enhance the control performance of the teleoperation system. In addition, due to unskilful operation and muscle physiological tremor of the human operator, a virtual fixture method is developed to ensure accuracy of operation and to reduce the operation pressure on the human operator. Experimental results demonstrated the effectiveness of the proposed method for the teleoperated robot.     

面向双操作者的六足机器人共享遥操作

随着六足机器人遥操作系统研究工作的日趋深入,针对其操控系统的开发也将面临诸多挑战.为了实现双人操控条件下各操作者的控制权重实时分配,设计一种基于透明性及控制状态(TCS)的六足机器人双用户控制权重分配方法.其双主端与单从端采取位置-速度的交互模式,通过分析系统实时透明性与当前控制状态,构建三边遥操作控制律,实时计算共享因子,采用速度跟踪模式设计基于触觉力反馈的系统控制架构,并利用三端口绝对稳定定理确定控制律参数的稳定范围.最后,搭建半物理仿真实验平台并验证所设计的三边共享遥操作方法能够在兼顾系统安全性与透明性的同时以较高的效率与安全性实现六足机器人的双用户操控,并能充分考虑双用户的控制意图.     

Controller designs for bilateral teleoperation with input saturation

Input saturation raises a stability issue in a bilateral teleoperation system when a master robot whose motion is induced by a human operator moves fast in abnormal situation and a slave robot cannot follow the motion command due to the input saturation. In this paper, we conduct rigorous stability analyses of the teleoperation system under the input saturation. We first extend analysis of teleoperation scheme proposed in Chopra and Spong (2004) to a case of the input saturation, in which analysis is valid for a local operation region whose size is dependent on the input capacity. We further develop a new control scheme that guarantees the stability for a global operation region. Therefore, the proposed control scheme can deal with extreme cases, e.g., the speed of motion of the master robot can be substantially greater than the actuator capability of the slave robot. Simulations and experiments are subsequently conducted to verify the effectiveness of the analyses.     

Integrated adaptive robust control for multilateral teleoperation systems under arbitrary time delays

With the increasing industrial requirements such as bigger size object, stable operation, and complex task, multilateral teleoperation systems extended from traditional bilateral teleoperation are widely developed. In this paper, the integrated control design is developed for multilateral teleoperation systems, where n master manipulators are operated by human to remotely control n slave manipulators cooperatively handling a target object. For the first time, the control objectives of multilateral teleoperation including stability, synchronization, transparency, and internal force distribution are clarified systematically. A novel communication architecture is proposed to cope with communication delays, where the estimated environmental parameters are transmitted from the slave side to the master, to replace the traditional environmental force measurement in the communication channel. A kind of nonlinear adaptive robust control technique is used to deal with nonlinearities, unknown parameters, and modeling uncertainties existing in the master, slave, and environmental dynamics, so that the excellent tracking performance is achieved in both master and slave sides. The coordinated motion/force control is designed in the slave side by the optimal internal force distribution among n slave manipulators, and the impedance control is designed in the master side to realize the target transparency behavior. In summary, the proposed control algorithm can achieve the guaranteed robust stability, the excellent synchronization and transparency performance, and the optimal internal force distribution simultaneously for multilateral teleoperation systems under arbitrary time delays and various modeling uncertainties. The simulation is carried out on a 2‐master/2‐slave teleoperation system, and the results show the effectiveness of the proposed control design. Copyright © 2015 John Wiley & Sons, Ltd.     

Robustly Stable Adaptive Control of a Tandem of Master–Slave Robotic Manipulators With Force Reflection by Using a Multiestimation Scheme

The problem of controlling a tandem of robotic manipulators composing a teleoperation system with force reflection is addressed in this paper. The final objective of this paper is twofold: 1) to design a robust control law capable of ensuring closed-loop stability for robots with uncertainties and 2) to use the so-obtained control law to improve the tracking of each robot to its corresponding reference model in comparison with previously existing controllers when the slave is interacting with the obstacle. In this way, a multiestimation-based adaptive controller is proposed. Thus, the master robot is able to follow more accurately the constrained motion defined by the slave when interacting with an obstacle than when a single-estimation-based controller is used, improving the transparency property of the teleoperation scheme. The closed-loop stability is guaranteed if a minimum residence time, which might be updated online when unknown, between different controller parameterizations is respected. Furthermore, the analysis of the teleoperation and stability capabilities of the overall scheme is carried out. Finally, some simulation examples showing the working of the multiestimation scheme complete this paper.     

Robustly stable adaptive control of a tandem of master-slave robotic manipulators with force reflection by using a multiestimation scheme.

The problem of controlling a tandem of robotic manipulators composing a teleoperation system with force reflection is addressed in this paper. The final objective of this paper is twofold: 1) to design a robust control law capable of ensuring closed-loop stability for robots with uncertainties and 2) to use the so-obtained control law to improve the tracking of each robot to its corresponding reference model in comparison with previously existing controllers when the slave is interacting with the obstacle. In this way, a multiestimation-based adaptive controller is proposed. Thus, the master robot is able to follow more accurately the constrained motion defined by the slave when interacting with an obstacle than when a single-estimation-based controller is used, improving the transparency property of the teleoperation scheme. The closed-loop stability is guaranteed if a minimum residence time, which might be updated online when unknown, between different controller parameterizations is respected. Furthermore, the analysis of the teleoperation and stability capabilities of the overall scheme is carried out. Finally, some simulation examples showing the working of the multiestimation scheme complete this paper.     

Real-time Velocity Alteration Strategy for Collision-free Trajectory Planning of Two Articulated Robot Manipulators

Two articulated robots working in a shared workspace can be programmed by planning the tip trajectory of each robot independently. To account for collision avoidance between links, a real-time velocity alteration strategy based on fast and accurate collision detection is proposed in this paper to determine the step of next motion of slave (low priority) robot for collision-free trajectory planning of two robots with priorities. The effectiveness of the method depends largely on a newly developed method of accurate estimate of distance between links. By using the enclosing and enclosed ellipsoids representations of polyhedral models of links of robots, the minimum distance estimate and collision detection between the links can be performed more efficiently and accurately. The proposed strategy is implemented in an environment where the geometric paths of robots are pre-planned and the preprogrammed velocities are piecewise constant but adjustable. Under the control of the proposed strategy, the master robot always moves at a constant speed. The slave robot moves at the selected velocity, selected by a tradeoff between collision trend index and velocity reduction in one collision checking time, to keep moving as far as possible and as fast as possible while avoid possible collisions along the path. The collision trend index is a fusion of distance and relative velocity between links of two robots to reflect the possibility of collision at present and in the future. Graphic simulations of two PUMA560 robot arms working in common workspace but with independent goals are conducted. Simulations demonstrate the collision avoidance capability of the proposed approach as compared to the approach based on bounding volumes. It shows that advantage of our approach is less number of speed alterations required to react to potential collisions.     

Adaptive control of bilateral teleoperation system with compensatory neural-fuzzy controllers

This paper presents two adaptive neural-fuzzy controllers equipped with compensatory fuzzy control in order to adjust membership functions, and as well to optimize the adaptive reasoning by using a compensatory learning algorithm. To the first controller is applied compensatory neural-fuzzy inference (CNFI) and to the second compensatory adaptive neural fuzzy inference system (CANFIS). Each controller is incorporated into a two channel bilateral teleoperation architecture involving force-position scheme, which combines the position control of the slave system with force reflection on the master. An analysis of stability and transparency based on a passivity framework is carried out. The resulting controllers are implemented on a one degree of freedom teleoperation system actuated by DC motors. The experimental results obtained show a fairly high accuracy in terms of position and force tracking, under free space motion and hard contact motion, what highlights the effectiveness of the proposed controllers.