地面和空间机械臂的动力学等效条件与控制相似律

针对如何在地面机械臂上有效验证空间机械臂控制律的问题,本文研究空间机械臂和地面机械臂系统间的动力学等效条件和控制相似律.首先,基于量纲分析研究地面机械臂和空间机械臂之间的动力学等效条件,并基于等效条件设计地面机械臂系统.其次,基于量纲分析建立空间和地面机械臂系统间的控制相似律,设计的空间机械臂控制律通过控制相似律将可以转化为地面机械臂相应的控制律.最后,考虑地面机械臂基座往往无法和空间机械臂的基座航天器一样进行全6自由度运动,以及地面机械臂运动时受到重力影响,使得地面机械臂不再满足动力学等效条件,基于反馈线性化技术设计一种地面机械臂的动力学误差补偿策略,使得地面机械臂和空间机械臂具有相似的闭环动力学行为.这样,空间机械臂的控制律可以在设计的地面机械臂上进行验证,仿真中以在地面机械臂上验证空间机械臂的PID控制器为例说明所提方法的有效性.     

Master-slave intelligent robot telepresence system

In this paper, the analysis and design of master-slave intelligent robot telepresence system are discussed. When the operator acts on the master manipulator, the position and attitude information of the master manipulator are gathered by the computer. After calculating and coordinate transforming, the data are send to the computer of the slave manipulator. Then the slave manipulator-PUMA562 robot follows the master manipulator's movement precisely. Six-dimension force/toque sensor(lord cell) is mounted on the slave manipulator. As the master manipulator and the toque on the slave manipulator are different in structure, the force and the slave manipulator should be send to the master manipulator computer and dissociated by the master manipulator computer. Proper ratio of the force on the master manipulator and the force on the slave manipulator is selected, and distribute to the master manipulator joints. So that the operator could feel the force from the master manipulator, which is obtained by the motors of the joints. The proposed control scheme is introduced to a prototype master-slave system and the experimental results show the validity of the proposed scheme.     

Kinematic Design and Analysis of a 7 Degree-of-Freedom Dual-Stage Inspection Manipulator for Dexterous Subsea Applications

This paper describes the design of a 7 degree-of-freedom (d.o.f) manipulator for underwater inspection applications. The functional requirements of an underwater manipulator for subsea inspection are discussed and the desired performance requirements identified. The inspection process of a weld joint using a manipulator is described and the desirable attributes of a 5 d.o.f manipulator for the inspection process established. A novel kinematic structure, for Underwater Robotic Vehicle (URV) operation, having a 2 d.o.f launching stages and a 5 d.o.f inspection stage is proposed for the manipulator. This configuration increases the dexterity, without compromising on the total reach of the manipulator. The kinematic structure of the 7 d.o.f, 2 stage, manipulator is presented. A hybrid power actuation is proposed for the manipulator to exploit the benefits of both hydraulic as well as electric actuators. Kinematic analysis of the manipulator is presented. The link dimensions of the inspection stage manipulator is done on the basis of kinematic performance indices of the manipulator. The novel kinematic structure and the hybrid power actuation strategy results in a power efficient, dexterous manipulator for underwater applications.     

Impedance control of a direct-drive manipulator without using force sensors

This research is concerned with impedance control of a manipulator which carries out stable contact tasks. The method controls the dynamic interaction between a robot and its environment by changing the apparent mechanical impedance of the manipulator. Conventional impedance control methods required force or torque sensors, which made the manipulator system very complex. In this paper a new method is proposed for controlling the impedance of a manipulator without using force or torque sensors. The angular velocity and angular acceleration of the manipulator joints are estimated, and by using a computer model of the manipulator, the necessary torque for each joint is calculated and applied to the joint to attain the desired impedance. The feasibility of the method is verified by surface-following experiments and collision experiments using a two-degree-of-freedom direct-drive manipulator.     

PD manipulator controller with fuzzy adaptive gravity compensation

This paper presents a PD manipulator controller with fuzzy adaptive gravity compensation. The main idea is to use a fuzzy adaptive controller to compensate for the gravity term of the robotic manipulator. This controller is designed by using Lyapunov's stability theorem, which guarantees system stability. Simulation is implemented on a two‐link manipulator by using MATALAB and SIMULINK. The results show that this fuzzy adaptive controller makes the manipulator trajectory converge to a desired position. Compared with other proposed fuzzy adaptive manipulator controllers, the PD manipulator controller with fuzzy adaptive gravity compensation is conceptually and structurally simpler and guarantees zero position error. ©2000 John Wiley & Sons, Inc.     

运动学补偿的宏2微机器人连续轨迹控制研究

一小机械手附在一大机械手末端构成的系统称为宏－微机器人系统,介绍了宏－微机器人连续轨迹控制的新方法,对宏－微机器人的控制在关节空间进行,通过微机械手的快速运动对宏机械手的轨迹误差在线补偿,宏－微机器人轨迹规划离线进行,通过任务放大的方法分解宏－微机器人运动学冗余,仿真和实验证明了方法的有效性。     

基于压力反馈控制的车间机械手智能防碰撞监测系统设计

针对目前提出的车间机械手智能防碰撞监测系统监测精准度低,防碰撞效果较差的问题,提出基于压力反馈控制的车间机械手智能防碰撞监测系统。硬件系统引入自动调心装置,在机械手内部加入两个避碰开关,将避碰开关与报警器相连接,如果出现碰撞,则发出警报,引用JCQ1工作监测器与机械手串联,确定机械手的工作状态和动作次数。软件部分依据机械臂运动的特点,设置机械手双动式液压缸和臂架单活塞杆双动式液压缸,通过压力反馈计算活塞直径得到液压缸直径,判断最大流量,将判断结果与阈值进行对比,完成防碰撞软件监测。实验结果表明,基于压力反馈控制的车间机械手智能防碰撞监测系统能够更加精准地控制机械手智能防碰撞监测数据,防碰撞控制精度较高,说明所设计系统能够有效实现间机械手智能防碰撞。     

Structures and characteristics of parallel manipulators

Parallel structures have remarkable characteristics such as high precision, high load capacity, high rigidity and high speed. Therefore, they have received a lot of attention as alternative structures for robot manipulators. This paper reviews the recent results on properties of the parallel manipulator. First, the basics of the link mechanism, which is necessary to understand the structure of the parallel manipulator, is summarized before the structure of the parallel manipulator is defined. Then, the parallel manipulator is compared with the serial manipulator. The singular point of the parallel manipulator and the optimum design of the structure of the parallel manipulator are also discussed.     

Analysis of stiffness and elastic deformation of a 2(SP+SPR+SPU) serial–parallel manipulator

A 2(SP+SPR+SPU) manipulator is a serial–parallel manipulator, which includes an upper manipulator and a lower manipulator. Its stiffness and elastic deformation are studied systematically in this paper. Firstly, a 2(SP+SPR+SPU) manipulator is constructed and its characteristics are analyzed. Secondly, the formulae for solving the elastic deformation and the compliance matrix of the active legs are derived and the elastic deformation and the total stiffness matrix of this manipulator are solved and analyzed. Finally, a finite element model of this manipulator is constructed and its elastic deformations are solved. The analytic solutions of elastic deformations of this manipulator are coincident with that of its finite element model.     

Three-dimensional shape recognition method using ultrasonics for manipulator control system

This article describes a three-dimensional shape recognition method that employs an ultrasonic distance sensor mounted on a manipulator, and its application to a manipulator control system. The principle of the method is to reconstruct an object surface numerically using both distance and orientation informations of an object. The method makes it possible to control the manipulator, to set the sensor in any position and orientation employing freedom of the manipulator, and to measure the object. The method is available for manipulator control because it can precisely assess the distance from the manipulator to the object, as well as reconstruct the object shape. Experimental results show that the newly developed method make object shape recognition easy and inexpensive. Application experiment proved that the method is effective for manipulator work due to its provision of distance information.     

基于专家PID的带臂四旋翼无人机控制方法

相较于未带臂的无人机,带臂无人机（UAV）的飞行轨迹会出现较大偏差,更难以稳定控制。为了解决带臂UAV的精确轨迹控制问题,提出基于专家PID的带臂四旋翼无人机控制方法。首先,将机械臂搭载于UAV上把它们作为整体,并通过拉格朗日方程建立了带臂UAV的运动学和动力学系统模型;其次,设计专家PID控制器用于对系统的稳定控制;然后利用五次多项式对带臂UAV的机械臂进行轨迹规划;最后,通过仿真验证专家PID控制方法对带臂UAV稳定控制的有效性。实验结果表明,相较于常规PID控制,所提基于专家PID的控制方法提高了系统的响应速度,且能够有效地抑制外部扰动;该方法对于动作情况下的机械臂能够稳定地跟踪其轨迹,且具有很好的抗扰性和鲁棒性。     

基于CAN总线控制系统的航天特种机械臂设计

航天特种机械臂具备精确操作和视觉识别的能力,在载人航天领域中广泛应用,为了在复杂环境中精准完成陆基装配任务,设计基于CAN总线控制系统的航天特种机械臂。从关节、连杆、驱动电机、锁紧制动器等方面,组装航天特种机械臂结构元件。装设航天特种机械臂控制器,在控制器中加设一个串行通信接口,将控制器连接到CAN总线中,配置CAN总线控制系统的通信协议,完成航天特种机械臂硬件结构设计。利用航天特种机械臂中传感器设备,检测航天特种机械臂实时位姿,补偿航天特种机械臂重力负载。根据机械臂工作任务,规划移动轨迹,在控制器的支持下,通过控制量的计算与通信,实现航天特种机械臂的控制功能。性能测试实验表明,设计基于CAN总线控制系统的航天特种机械臂平均位置和关节姿态角的控制误差分别为3.0m和0.32°,平均形变量为2.64m2,具有较好的控制性能和抗压性能。     

Gravity compensation of spatial two‐DOF serial manipulators

This article presents the analysis of gravity compensation of a two‐DOF serial manipulator operating in three‐dimensional space by means of linear spring suspension. The physical configuration of the serial manipulator is assumed general. The analysis begins with gravity compensation of a one‐DOF manipulator in order to form the basis which is then extended to a two‐DOF manipulator. The approach taken in the analysis is that of conservation of potential energy. The goal is to seek the location and the stiffness of springs that provide complete compensation of gravity in the manipulator system. It has been found that complete compensation of gravity in a two‐DOF serial manipulator system is possible. Unlike many previous works on spring suspension of a rigid body, which assume that one end of the suspending spring is attached to ground, it is proven in this study that, for complete compensation in a two‐DOF manipulator, the spring that suspends the distal link cannot be connected to ground. Instead, it must be in certain motion relative to the proximal link. The discussion on how to provide such a motion for the spring is given. It is also explained how the problem of gravity compensation of a robot manipulator can be shifted to that of changing gravity environment within a manipulator system. The concept can be applied to simulation and testing of robot manipulators that will be sent to operate in a different gravity environment, such as space. © 2002 Wiley Periodicals, Inc.     

模块化超冗余度空间机械臂的设计与实验

针对空间在轨服务任务需求设计了一种9自由度的模块化超冗余空间机械臂。该机械臂由9个相同的机械臂关节构成,其关节数量可根据任务要求进行调整。模块化关节采用一体化设计,关节内部合理地布置了机械传动部分与电气部分。基于改进的Bi-RRT算法和建立的机械臂的正逆运动学模型,机械臂进行了穿越复杂障碍环境的仿真和实验,实验结果表明该机械臂可以灵活地穿越障碍环境。基于阻抗控制算法,分别采用该机械臂进行了写字实验和恒力保持实验,实验结果表明机械臂具有良好的力控制能力。实验验证了该机械臂具备在复杂空间环境中执行在轨服务的能力。     

Endogenous configuration space approach to mobile manipulators: A derivation and performance assessment of Jacobian inverse kinematics algorithms

By a mobile manipulator we mean a robotic system composed of a non-holonomic mobile platform and a holonomic manipulator fixed to the platform. A taskspace of the mobile manipulator includes positions and orientations of its end effector relative to an inertial coordinate frame. The kinematics of a mobile manipulator are represented by a driftless control system with outputs. Admissible control functions of the platform along with joint positions of the manipulator constitute the endogenous configuration space. Endogenous configurations have a meaning of controls. A map from the endogenous configuration space into the taskspace is referred to as the instantaneous kinematics of the mobile manipulator. Within this framework, the inverse kinematic problem for a mobile manipulator amounts to defining an endogenous configuration that drives the end effector to a desirable position and orientation in the taskspace. Exploiting the analogy between stationary and mobile manipulators we present in the paper a collection of regular and singular Jacobian inverse kinematics algorithms. Their performance is evaluated on the basis of intense computer simulations.     

基于卷积神经网络的机械臂抓取控制系统设计

为保证机械臂的抓取精度,保证物体抓取的稳定性,本文设计基于卷积神经网络的机械臂抓取控制系统。在系统硬件部分,加设图像、位置和压力传感器,改装机械臂抓取控制器和运动驱动器,利用图像传感器设备,获取满足质量要求的机械臂抓取目标图像,为机械臂抓取控制功能提供硬件支持。软件部分利用卷积神经网络算法提取图像特征,确定机械臂抓取目标位置。结合机械臂当前位置的检测结果,规划机械臂抓取路线,预估机械臂抓取角度与抓取力。最终通过机械臂抓取参数控制量的计算,在控制器的支持下实现系统的机械臂抓取控制功能。实验结果表明,所设计系统应用下位置控制误差和速度控制误差的平均值分别为0.192m和0.138m/s,同时物体抓取掉落概率明显降低。     

Large force generation and control method of manipulator exploiting its oscillatory motion using Van Der Pol oscillator

In this study, the effect of exploiting an oscillatory motion of a manipulator on large force generation is demonstrated using simulations. Firstly, a natural frequency approximation method is devised, and a preferable posture of the manipulator is selected based on the approximation. The preferable posture is a posture in which the natural frequency of the manipulator is low. Since, in general, high frequency vibration is considered to be an undesirable phenomenon for mechanical systems, the manipulator should be operated in the preferable posture. Secondly, a method to oscillate the manipulator is proposed, and its performance is investigated using simulations. The method capitalizes on the oscillatory motion of the manipulator for efficient large force generation. Specifically, the method uses Van der Pol (VDP) oscillator to exploit an oscillatory motion of the manipulator. A force reference signal, which is a command to make the manipulator oscillate, is produced by the VDP oscillator. Due to the entrainment property of the VDP oscillator, the force reference signal can synchronize with the motion of the manipulator. The efficient large force generation is attained by the synchronization. Thirdly, a force control system that enables you to obtain the desired amount of force is designed based on the force generation method. By adjusting the natural frequency of the VDP oscillator, the purpose of the force control system is realized. Finally, a theoretical proof of the entrainment property of the VDP oscillator coupled with a linear mechanical system is established with an averaging method, and simulations exemplify the validity of the proof.     

Investigating Dynamic Interaction between the One D.O.F. Manipulator and Vehicle of a Mobile Manipulator

A manipulator mounted on a moving vehicle is called a mobile manipulator. A mobile manipulator with an appropriate suspension system can pass over uneven surfaces, thus having an infinite workspace. If the manipulator could operate while the vehicle is traveling, the efficiency concerning with the time and energy used for stopping and starting will be increased.This paper presents the kinematic and dynamic modeling of a one degree of freedom manipulator attached to a vehicle with a two degrees of freedom suspension system. The vehicle is considered to move with a constant linear speed over an uneven surface while the end effector tracks a desired trajectory in a fixed reference frame. In addition, the effects of dynamic interaction between the manipulator and vehicle (including the suspension system"s effects) have been studied. Simulation results from straight line trajectory are presented to illustrate these effects.     

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.