工业机器人遥操作系统的空间映射与控制策略

针对工业机器人遥操作系统中存在的主从机器人工作空间差异以及运动控制精度与安全问题,提出了一种工作空间映射算法与位置—速度混合控制策略。首先,将遥操作划分为自由运动和交互两个阶段,在自由运动阶段采用映射算法使主从机器人的工作空间高度覆盖,使主机器人可操控的从机器人运动范围最大化。进一步,在交互阶段设计了一种位置—速度混合控制策略对工业机器人的运动进行准确的控制,使主从机器人的实际位置轨迹准确的跟随,并进一步引入反馈引导力以实现安全的控制。最后在Touch-ABB IRB120主从机器人遥操作实验平台上对所提控制方法进行验证,实验结果表明该方法使得主从机器人运动范围在高度覆盖的同时可以保证遥操作控制的精度。     

Obstacle Modelling Oriented to Safe Motion Planning and Control for Planar Rigid Robot Manipulators

Trajectory planning and tracking are crucial tasks in any application using robot manipulators. These tasks become particularly challenging when obstacles are present in the manipulator workspace. In this paper a n-joint planar robot manipulator is considered and it is assumed that obstacles located in its workspace can be approximated in a conservative way with circles. The goal is to represent the obstacles in the robot configuration space. The representation allows to obtain an efficient and accurate trajectory planning and tracking. A simple but effective path planning strategy is proposed in the paper. Since path planning depends on tracking accuracy, in this paper an adequate tracking accuracy is guaranteed by means of a suitably designed Second Order Sliding Mode Controller (SOSMC). The proposed approach guarantees a collision-free motion of the manipulator in its workspace in spite of the presence of obstacles, as confirmed by experimental results.     

工业机器人的工作空间综合

根据机器人工作位姿要求确定其自由度数，关节类型及排列，杆件尺寸，关节运动范围，机器人的位置等过程称为机器人的工作空间综合过程，本文侧重对已知的机器人结构提出了进行工作空间综合的优化方法。     

Experimental investigation on coverage performance of a chaotic autonomous mobile robot

In many autonomous mobile robotic missions the complete and fast coverage of the workspace, scanned by an unpredictable trajectory, plays a crucial role. To satisfy these special demands in the design of an autonomous mobile robot, a motion controller, based on the dynamical behavior of a known discrete chaotic system, the Logistic map, is presented in this paper. The proposed method is based on a microcontroller for realizing a chaotic random bit generator and converting the produced chaotic bit sequence, to the robot’s trajectory of motion. The experimental results confirm that this approach, with an appropriate sensor for obstacle avoidance, can obtain very satisfactory results in regard to the fast scanning of the robot’s workspace with unpredictable way.     

一种能应付突发意外事件的装配机器人运动规划研究

本文基于运动规划的拓扑方法，针对机械手的装配环境，提出了一种能应付突发意外事件－即能躲避突发障碍继续到达目标位置的运动规划方法，该方法主要包含三部分：用已知信息进行运动规划；遇到突发障碍后进行局部调整；局部调整失败时进行全局重规划，本文给出一种运动规划器ＥＴＴＭＰ，经实验测试，该规划器具有较强的鲁棒性和实时性，为智能机器人的实用化研究提供了一种方法。     

冗余度机器人自运动中的混沌运动及其控制

以一个平面3R刚性冗余度机器人为研究对象,采用PD调节器进行工作空间内的负反馈,控制机器人末端重复跟踪工作空间内封闭路径,对此过程中机器人自运动中可能存在的混沌运动进行了研究.通过运动仿真和相图,以及计算系统的最大李亚普诺夫指数,研究发现,基于雅可比矩阵的伪逆,求解冗余度机器人运动学逆解时其自运动是混沌的.首次应用延迟反馈控制法对所发现的混沌运动进行控制,在适当的参数条件下,成功地将混沌运动转变为规则的周期运动.􀁱 􀁽     

连续体单孔手术机器人的建模与优化分析

提出了一种新构型的6自由度连续体单孔手术机器人．其形变骨架采用超弹性材料一体化成型加工,具有一系列十字交叉镂空结构的弹性铰链．建立了机器人的运动学模型,分析了机器人的可达工作空间,提出一种手术作业空间的优化搜索方法,获得了作业空间中关键位置的操作灵活性．进而以操作灵活性为目标,以关节形变能力为约束,优化分析连续体机构形变骨架的几何参数,形成提升连续体单孔手术机器人操作灵活性的参数优化方法．最后进行连续体机器人的运动控制实验,经过测试,机器人的末端位置误差为2.23 mm,角度误差为2.06°,验证了模型的准确性．     

基于引力自适应步长RRT的双臂机器人协同路径规划

快速扩展随机树（RRT）方法的步长确定过分依赖于程序调试,而且固定的步长会导致碰撞检测失效问题．针对此问题,本文提出一种适用于双臂机器人协同路径规划的引力自适应步长RRT．首先,通过建立构型空间与工作空间的步长范数不等式,对双臂机器人在工作空间中所产生的步长进行约束,进而确保实现有效的碰撞检测;然后,提出随机树被动生长方法,在保证双臂机器人协同运动的基础上,降低规划空间的维度．最后,在随机树的节点处引入引力函数,加快算法的融合速度．仿真结果表明,引力自适应步长RRT方法可对工作空间中的步长进行有效约束,确保算法碰撞检测的有效性．在无碰撞的前提下,引力自适应步长RRT方法相比于其他算法减少了迭代次数,降低了运行时间并缩短了路径长度．将所提算法应用于双臂机器人的样机实验,结果表明双臂机器人可在保持位置协同的前提下,完成避障运动,验证了算法的可行性．     

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．     

A parallel machining robot and its control method for high-performance machining of curved parts

The curved part with open-and-close angle conversion features is a kind of well-known difficult-to-machine part. Using traditional five-axis serial machine tools (SMTs) may cause efficiency and accuracy reduction at open-and-close angle conversion regions because of the singular points in their orientation workspace. How to achieve high-efficiency and high-precision machining of this kind of curved part is a challenging issue in the field. In order to solve this problem, a parallel machining robot (PMR) with five degrees of freedom (DoFs) is developed. Accordingly, the attitude coupling adjustment mechanism of the developed PMR is disclosed, which indicated that a small change of the tool orientation will never lead to a large range motion of the driving limbs. Thus the robot has the potential to pass through open-and-close angle conversion regions smoothly. In order to take full use of the advantages of the developed PMR in attitude adjustment, a control method is proposed by fitting tool orientation spline in unit spherical coordinate system. On this basis, toolpath planning and machining experiments are carried out to verify the performance of the developed PMR and the proposed control method when machining parts with open-and-close angle conversion features. Experimental results demonstrate that the developed machining robot integrated with the proposed control method can improve the machining efficiency and accuracy significantly when compared with the SMT. This proves that the attitude coupling motion property of PMRs can solve the difficulty in high-performance machining of open-and-close angle conversion features. The findings of this study fundamentally provide a feasible way to overcome the abnormal phenomena when machining curved parts with open-and-close angle conversion features.     

3D Collision-Free Motion Based on Collision Index

A collision-free motion planning method for mobile robots moving in 3-dimensional workspace is proposed in this article. To simplify the mathematical representation and reduce the computation complexity for collision detection, objects in the workspace are modeled as ellipsoids. By means of applying a series of coordinate and scaling transformations between the robot and the obstacles in the workspace, intersection check is reduced to test whether the point representing the robot falls outside or inside the transformed ellipsoids representing the obstacles. Therefore, the requirement of the computation time for collision detection is reduced drastically in comparison with the computational geometry method, which computes a distance function of the robot segments and the obstacles. As a measurement of the possible occurrence of collision, the collision index, which is defined by projecting conceptually an ellipsoid onto a 3-dimensional Gaussian distribution contour, plays a significant role in planning the collision-free path. The method based on reinforcement learning search using the defined collision index for collision-free motion is proposed. A simulation example is given in this article to demonstrate the efficiency of the proposed method. The result shows that the mobile robot can pass through the blocking obstacles and reach the desired final position successfully after several trials.     

A geometric approach to solving the stable workspace of quadruped bionic robot with hand–foot-integrated function

This paper discusses stable workspace of a hand–foot-integrated quadruped walking robot, which is an important issue for stable operation of the robot. This robot was provided with combined structure of parallel and serial mechanisms, whose stable workspace was the subspace of the workspace in which the system was considered stable. The reachable region was formed under structural conditions, while the stable space was formed by the overall conditions of stability which changed with the robot's pose and the mass of grabbed object. In this paper, based on the robot's main structure, the key issues in solving the robot's workspace are discussed in detail, including searching steady conditions of operation of the robot. To research the robot's workspace, working leg's motion curve needed to be solved by kinematics analysis. Due to the redundant drive, it was problematic to deal analytically with the kinematics of the quadruped walking robot. A geometric method of kinematic analysis was proposed as well. Based on the geometric method, the workspace of the robot under varying postures was analyzed by the method of grid partition and in combination with Matlab, VB and Solidworks software programs. An automated computational system of the stable workspace was developed and an example was given to illustrate the whole process in detail. The theory and analysis procedures were also verified by simulation of the robot and its actual grabbing of an object.     

基于三维环境模型的启发式路径规划算法

针对多自由度机器人手臂在未知环境中实时避障的问题,提出了一种基于环境信息的连杆机器人实时路径规划方法。采用笛卡尔空间内的障碍物检测信息建立了障碍物的空间模型,并依据该模型设计一种基于启发式规则的机器人路径规划算法。该算法不断猜测和修正路径,通过模糊推理得到下一位姿点,通过曲线拟合得到到达该位姿点的路径。在Matlab下利用机器人工具箱建立了PUMA560型机器人的运动学模型,并在运动空间设置障碍物,对该算法进行仿真分析,分析结果说明所提出的路径规划算法可以在较短时间内完成避障运动,具有较好的实时性,同时运动关节的角度变化曲线比较平滑,运动中冲击力较小,这些特点使其便于在实际工程中使用。     

On-line collision avoidance system for two PTP command-based manipulators with distributed controller

This research aims to solve online collision avoidance problem of two manipulators with independent controller. Since industrial robot controller is a closed commercial system, trajectory generation part of robot controlling is always proprietary or unknown. Thus, this paper proposes a collision avoidance system of two manipulators which are controlled by point-to-point (PTP) commands, in condition that the internal of robot controller is unknown and unchangeable. Based on this condition, collision avoidance is supposed to be realized by online scheduling of these PTP controlling commands. This paper proposes the collision avoidance method that assumes the three-dimensional common workspace between two manipulators can be partitioned into many subregion elements. And with managing these subregion elements, which are occupied by robot motion, PTP commands are scheduled to adjust execution timing for collision avoidance. A deadlock problem caused by the partition of the workspace is also taken into consideration in the method. And the effectiveness and efficiency of the method have been verified by simulations and experiments.     

Inverse Kinematics and Workspace Analysis of a 3 DOF Flexible Parallel Humanoid Neck Robot

To mimic the human neck’s three degree-of-freedom (DOF) rotation motion, we present a novel bio-inspired cable driven parallel robot with a flexible spine. Although there exists many parallel robotic platform that can mimic the human neck motion, most of them have only two DOF, with the yaw motion being actuated separately. The presented flexible parallel humanoid neck robot employs a column compression spring as the main body of cervical vertebra and four cables as neck muscles to connect the base and moving platform. The pitch and roll movements of moving platform are realized by the two dimensional lateral bending motion of the flexible spring, and a bearing located at the top of the compression spring and embedded in the moving platform is used to achieve the yaw motion of the moving platform. By combing the force and torque balance equations with the lateral bending statics of the spring, inverse kinematics and optimizing the cable placements to minimize the actuating cable force are investigated. Moreover, the translational workspace corresponding to pitch and roll movements and rotational workspace corresponding to yaw movement are analyzed with positive cable tension constraint. Extensive simulations were performed and demonstrated the feasibility and effectiveness of the proposed inverse kinematics and workspace analysis of the novel 3 DOF flexible parallel humanoid neck robot.     

Design of a spherical parallel kinematic machine for ankle rehabilitation

Existing ankle rehabilitation robots have the limitations of insufficient motion ranges and coupled translations. An improved spherical robot has been proposed to overcome these limitations. The forward and inverse kinematic problems of this new machine are formulated and solved; the dexterity of the workspace is evaluated and the workspace has been optimized with the consideration of the motion ranges of passive joints. The operation of machine has been simulated; it will be further expanded as a control program to run the rehabilitation robot.     

A novel XY-Theta precision table and a geometric procedure for its kinematic calibration

Spatial precision positioning devices are often based on parallel robots, but when it comes to planar positioning, the well-known serial architecture is virtually the only solution available to industry. Problems with parallel robots are that most are coupled, more difficult to control than serial robots, and have a small workspace. In this paper, new parallel robot is proposed, which can deliver accurate movements, is partially decoupled and has a relatively large workspace. The novelty of this parallel robot lies in its ability to achieve the decoupled state by employing legs of a different kinematic structure. The robot repeatability is evaluated using a CMM and so are the actual lead errors of its actuators. A simple geometric method is proposed for directly identifying the actual base and mobile reference frames, two actuator's offsets and one distance parameter, using a measurement arm from FARO Technologies. While this method is certainly not the most efficient one, it yields a satisfactory improvement of the robot accuracy without the need for any background in robot calibration. An experimental validation shows that the position accuracy achieved after calibration is better than 0.339 mm within a workspace of approximately 150 mm×200 mm.     

On the Workspace of a Free-Floating Space Robot

The planar problem of controlling the motion of a free-floating space robot is investigated. The robot consists of a body and a telescopic manipulator arm. The motion of the manipulator arm changes the body’s center of mass and causes the body to rotate. It is assumed that the length of the manipulator arm and the angle of its turn relative to the body are restricted. It is shown that the workspace of such a robot is significantly larger than the workspace of a robot with a fixed body. Due to the special motions of the manipulator arm, the robot’s body can be turned and the gripper can be moved from an arbitrary position to another arbitrary position if they are within the workspace, which is a ring centered at the robot’s center of mass. In addition, the prescribed angle between the manipulator arm and the body in the terminal position can be ensured.     

Design and optimal control of dual-stage Stewart platform using Feedback-Linearized Quadratic Regulator

Design and optimal control of a dual-stage Stewart robot is performed in this paper using sequential optimal feedback linearization method considering the dynamics of the jacks. Considering the limited length of the jacks, the possible dynamic workspace of this robot is extremely limited. Dual-stage platform version of this robot is designed and proposed in this paper to improve this limitation. As a result, the dynamic workspace of the robot is increased by increasing the degrees of freedom (DOFs) of the system. Modeling and dynamics of the new proposed system are developed considering the dynamics of the jacks. Besides, the robot is controlled with the highest accuracy and the lowest energy using an optimal control strategy based on Feedback-Linearized Quadratic Regulator (FLQR). Two sequential controlling loops are employed for simultaneous control of the joint space and work space of the robot. The efficiency of the proposed manipulator toward increasing the workspace of the robot and also the accuracy of the proposed controller are investigated using MATLAB for a dual-stage Stewart robot. The kinematics and kinetics of the robot are extracted, the proposed controller is implemented and the results are analyzed which show the efficiency of the proposed structure and controlling method.