关节型机器人的似人操作构型规划

对关节型机器人的操作构型进行规划时,本文提出了一种新的规划方法,它结合了似人评估准则和机器人传速特性优化的概念,可实现有最大末端传速特性的操作,同时与人类手臂操作的特点最为相似.该方法首先利用应用人体工程学中的快速上肢评价准则(RULA)对机器人的操作空间进行划分,然后在各子空间内最大化机器人末端沿指定方向的传速速率.最终选定一个最符合人类操作特性又同时满足操作任务的机器人操作构型.通过在2自由度平面机器人和7自由度拟人机械臂上的规划实验进一步展示了本方法的使用,规划结果验证了其有效性.     

Robot arm-wrist coordination. Part 1. Quantitative rating

The robotic capability for controlled motion depends upon the robot's ability to coordinate its arm and wrist in order to accomplish the desired task. The objective of this article is to define formally the arm-wrist coordination and to introduce a quantitative measure for it. We develop a mathematical framework that provides for the analysis of the impact of both the fixed manipulator geometry and the changing robot configuration upon the efficiency of arm-wrist coordination. In the companion paper (Part 2). manipulator design guidelines are then formulated to guarantee task decomposition for any desired robot task. Numerical simulations demonstrate the efficacy of these design guidelines.     

Global Convergence of a Decentralized Adaptive Fuzzy Control for the Motion of Robot Manipulators: Application to the Mitsubishi PA10-7CE as a Case of Study

In general terms, robot control consists in making a robot execute a commanded task. One of the most important cases is the trajectory tracking or motion control. In this paper, a control algorithm that uses adaptive fuzzy systems to approximate local portions of the robot manipulator dynamics is proposed in order to solve the trajectory tracking problem. This scheme is characterized by not requiring any knowledge of the dynamic model and, in contrast to some fuzzy adaptive controllers previously developed, the one proposed here is in a decentralized configuration, wherein each joint is considered as a subsystem and is independently controlled only through its local variables. Furthermore, a study that guarantees the stability and the boundedness of the solutions of the closed-loop system via Lyapunov theory is presented, including a functional analysis which proves for the first time that a decentralized adaptive fuzzy controller satisfies the motion control objective. The theoretical results exposed here are verified via experimentation by applying the designed algorithm to the Mitsubishi PA10-7CE robot arm and the outcomes are reported.     

Gunryu III: reconfigurable magnetic wall-climbing robot for decommissioning of nuclear reactor

To perform the decommissioning on the inaccessible area to human workers, the need to develop a wall-climbing robot is increasing. In these wall-climbing robots, high mobility and stability on a surface of walls are most important required features. To achieve both of these features, the new type of arm-equipped reconfigurable multi-modules wall-climbing robot was proposed in this research. The stability and high mobility can be achieved by reconfiguration using attached arm as a connection mechanism. And the robot system composed of two mobile modules and 6DOF manipulator was developed as a proof mechanism. In this robot, for energy efficient and stable mobility at the environment of steel structure, the adsorption method based on magnet was selected and its functionality was confirmed. And, to enable intuitive control, the kinematic solver was developed and verified. Finally, basic experiment of motion test was performed, and it was confirmed that the proposed wall-climbing robot satisfies required functions, such as high mobility and stability.     

Robust motion control with the consideration algorithm of joint torque saturation for a redundant manipulator

As each joint actuator of a robot manipulator has a limit value of torque, the motion control system should consider the torque saturation. In order to consider the torque saturation in a transient state, this paper proposes a new redundant motion control system using the autonomous consideration algorithm on torque saturation. A Jacobian matrix of a redundant robot manipulator can select the optimal one considering its motion energy in the steady state. When the motion control system carries out fast motion and quick disturbance suppression, a high joint torque is required in a transient state. In the experimental results, under the condition of having a large payload torque and a fast motion reference, the proposed redundant manipulator control realizes the quick robot motion robustly and smoothly.     

Robot motion control in zero-gravity conditions

We have considered the motion control of a space robot composed of a body and a telescopic manipulator arm. The robot is in the state of free passive flight. The vector of the number of movements and the kinetic moment of the robot relative to the center of mass are zero. The manipulator arm motion causes a corresponding motion of the robot body (change in the position of the center of mass of the body and its rotation). Unlike earlier results, we have revealed that the robot grip can be shifted from an arbitrary initial position to an arbitrary final position inside the operating area and, in addition, the required (most convenient for operations) angle between the manipulator arm and the robot body in the final position can be obtained.     

Real-Time Motion Planning for a Volleyball Robot Task Based on a Multi-Agent Technique

This paper takes the volleyball robot task as an example of a dynamic manipulation task and presents a multi-agent-based motion-planning framework for it. Each subtask in the motion planning is defined as an agent. The motion planning is accomplished by the solution of each agent activated by a blackboard. It is convenient to extend the module and enable real-time control compared to the hierarchy and subsumption architecture. In the solution of each subtask, one difference from the motion planning of other ball-playing robots is that simple fuzzy rules are adopted to determine the hitting position, which leads to smaller hitting velocities beneficial for task control. The other difference is that the task-based directional manipulability measure (TDMM) is used to optimize the robot configuration on the basis of optimal hitting path, so as to improve the manipulating ability on task direction. The simulation of a planar three-link manipulator ball-hitting task is implemented by the MATLAB/Simulink tool. The virtual target of the hitting motion is validated on the ABB manipulator by the ball-catching experiment.     

Design parameter evaluation based on human operation for tip mechanism of forceps manipulator using surgical robot simulation

We proposed a design method for pediatric surgical robots that evaluates the workspace and view information in computer simulator before the actual robot is developed. In this study, we investigated a suturing task in a virtual environment using forceps manipulators with different mechanical parameters. We reproduced the surgical workspace for congenital esophageal atresia and measured the working volume and invisible area to obtain suitable parameters for the suturing task. We also calculated the suitable mechanical parameters using Pareto optimal solution method and verified the mechanical parameters in Pareto optimal solution. We verified from the experimental results that there is a trade-off between the working volume and invisible area during the suturing task. Moreover, we determined from the calculation results that the mechanical design of the forceps manipulator is influenced by the invisible area during the suturing task. Finally, we confirmed that it is possible to obtain suitable parameters for surgical robots using the proposed method.     

New approach to the application of redundant robots

The problem of a heavy robot performing highly accelerated motion is discussed. Since the original six degree of freedom configuration could not solve the task, a suitable redundancy was added to improve the acceleration capabilities. This redundant configuration equipped with the DPS (distributed positioning system) software was able to perform the motion required. The theoretical background and simulation results are presented.     

Conceptual design and analysis of the 2T1R mechanism for a cooking robot

This paper deals with the design and analysis of a two-translation and one-rotation (2T1R) mechanism for a novel cooking robot. Firstly the motions involved in stir-fry, the most representative operation in the cooking processes used in Chinese cuisine, are analyzed in details. Then the featured motions are decomposed into four main movements that are used as a design base for a wok motion mechanism. Several three-degrees-of-freedom (DOF) parallel manipulators are considered. From these, a 2T1R mechanism is selected as an ideal candidate. A 4-DOF (2T1R+1T) cooking robot is constructed by combining the 2T1R parallel manipulator with a 1-DOF linear feed mechanism. It is shown that the combined 4-DOF robot can perform the required cooking operations, particularly the stir-fry. The analysis conducted on the proposed 2T1R parallel manipulator includes inverse kinematics, forward kinematics, the velocity analysis, the constant orientation workspace, and the total orientation workspace. A prototype of the cooking robot is developed. The experiments verify that the proposed cooking robot is suitable for performing the required operations.     

基于似人特性的机器人拟人臂自主抓取动作规划

针对拟型服务机器人在家庭环境中的自主抓取任务,提出了一种强调运动姿态似人特性的机器人手臂动作的运动规划方法.该方法基于人体工程学中的快速上肢评估准则评价机器人运动姿态的似人特性,并在此基础上以机器人传速速率最优为目标规划机器人持物动作的姿态构型.最后以Motoman SDA10D拟人双臂机器人为例,具体介绍了该方法的应用和规划的结果,规划结果证明了该方法的可行性和有效性.     

A Sequential Bi-criteria Search Algorithm for Robot Path Planning in the Box Pushing Problem

The collision-free trajectory planning method subject to control constraints for mobile manipulators is presented. The robot task is to move from the current configuration to a given final position in the workspace. The motions are planned in order to maximise an instantaneous manipulability measure to avoid manipulator singularities. Inequality constraints on state variables i.e. collision avoidance conditions and mechanical constraints are taken into consideration. The collision avoidance is accomplished by local perturbation of the mobile manipulator motion in the obstacles neighbourhood. The fulfilment of mechanical constraints is ensured by using a penalty function approach. The proposed method guarantees satisfying control limitations resulting from capabilities of robot actuators by applying the trajectory scaling approach. Nonholonomic constraints in a Pfaffian form are explicitly incorporated into the control algorithm. A computer example involving a mobile manipulator consisting of nonholonomic platform (2,0) class and 3DOF RPR type holonomic manipulator operating in a three-dimensional task space is also presented.     

An efficient local approach for the path generation of robot manipulators

In this article an efficient local approach for the path generation of robot manipulators is presented. The approach is based on formulating a simple nonlinear programming problem. This problem is considered as a minimization of energy with given robot kinematics and subject to the robot requirements and a singularities avoidance constraint. From this formulation a closed form solution is derived which has the properties that allows to pursue both singularities and obstacle avoidance simultaneously; and that it can incorporate global information. These properties enable the accomplishment of the important task that while a specified trajectory in the operational space can be closely followed, also a desired joint configuration can be attained accurately at a given time. Although the proposed approach is primarily developed for redundant manipulators, its application to nonredundant manipulators is examplified by considering a particular commercial manipulator.     

Singularity-robust decoupled control of dual-elbow manipulators

The ability of a robot manipulator to move inside its workspace is inhibited by the presence of joint limits and obstacles and by the existence of singular positions in the configuration space of the manipulator. Several kinematic control strategies have been proposed to ameliorate these problems and to control the motion of the manipulator inside its workspace. The common base of these strategies is the manipulability measure which has been used to: (i) avoid singularities at the task-planning level; and (ii) to develop a singularity-robust inverse Jacobian matrix for continuous kinematic control. In this paper, a singularity-robust resolved-rate control strategy is presented for decoupled robot geometries and implemented for the dual-elbow manipulator. The proposed approach exploits the decoupled geometry of the dual-elbow manipulator to control independently the shoulder and the arm subsystems, for any desired end-effector motion, thus incurring a significantly lower computational cost compared to existing schemes.     

Robot arm-wrist coordination. Part 2. Design guidelines

In the companion article (Part 1), we developed a mathematical framework that provides for the analysis and quantitative rating of arm-wrist coordination. The objective of this article is to exploit this framework and formulate manipulator design guidelines for effective arm-wrist coordination and task execution. We explore various arm and wrist designs and quantify their performance in terms of meeting the two design objectives of efficient arm-wrist coordination and robot flexibility. Numerical simulation experiments highlight the measurable effects of both the fixed manipulator geometry and changing robot configuration on arm-wrist coordination and demonstrate the impact of the design guidelines on robot performance.     

Neural network Reinforcement Learning for visual control of robot manipulators

It is known that most of the key problems in visual servo control of robots are related to the performance analysis of the system considering measurement and modeling errors. In this paper, the development and performance evaluation of a novel intelligent visual servo controller for a robot manipulator using neural network Reinforcement Learning is presented. By implementing machine learning techniques into the vision based control scheme, the robot is enabled to improve its performance online and to adapt to the changing conditions in the environment. Two different temporal difference algorithms (Q-learning and SARSA) coupled with neural networks are developed and tested through different visual control scenarios. A database of representative learning samples is employed so as to speed up the convergence of the neural network and real-time learning of robot behavior. Moreover, the visual servoing task is divided into two steps in order to ensure the visibility of the features: in the first step centering behavior of the robot is conducted using neural network Reinforcement Learning controller, while the second step involves switching control between the traditional Image Based Visual Servoing and the neural network Reinforcement Learning for enabling approaching behavior of the manipulator. The correction in robot motion is achieved with the definition of the areas of interest for the image features independently in both control steps. Various simulations are developed in order to present the robustness of the developed system regarding calibration error, modeling error, and image noise. In addition, a comparison with the traditional Image Based Visual Servoing is presented. Real world experiments on a robot manipulator with the low cost vision system demonstrate the effectiveness of the proposed approach.     

Dragging motion of a two-link mobile manipulator with large pull force through singular configuration: theoretical analysis and experimental verification

This paper reveals the advantageous feature of singular configuration for a two-link mobile manipulator by theoretical analysis, numerical simulations and experiments. When a mobile manipulator drags a heavy object on a flat floor, a large pull force is required to overcome the friction force between the object and the floor. In the motion obtained by numerical optimization, unlike humans, a two-link mobile manipulator pulls the object with a large force by passing through singular configuration. We analyze theoretically the force applied to the object by the manipulator under several assumptions, and show that a large pull force can be generated near singular configuration from the energy stored in the manipulator. The feasibility of the motion obtained by numerical optimization is also shown by experimental results.     

GA-pattern matching-based manipulator control system for real-time visual servoing

_—In robotic applications, tasks of picking and placing are the most fundamental ones. Also, for a robot manipulator, the recognition of its working environment is one of the most important issues to do intelligent tasks, since this aptitude enables it to work in a variable environment. This paper presents a new control strategy for robot manipulators, which utilizes visual information to direct the manipulator in its working space, to pick up an object of known shape, but with arbitrary position and orientation. During the search for an object to be picked up, vision-based control by closed-loop feedback, referred to as visual servoing, is performed to obtain the motion control of the manipulator hand. The system employs a genetic algorithm (GA) and a pattern matching technique to explore the search space and exploit the best solutions by this search technique. The control strategy utilizes the found results of GA-pattern matching in every step of GA evolution to direct the manipulator towards the target object. We named this control strategy step-GA-evnlution. This control method can be applied for manipulator real-time visual servoing and solve its path planning problem in real-time, i.e. in order for the manipulator to adapt the execution of the task by visual information during the process execution. Simulations have been performed, using a two-link planar manipulator and three image models, in order to find which one is the best for real-time visual servoing and the results show the effectiveness of the control method.     

Methodology for the kinematical selection of a manipulator for a specified task

Manipulator design methodology is a recent and important issue in the robot design research area. Most importantly, to design a robot rationally, one must have a strong understanding of the design parameters of the manipulator, and of the characteristics of the robot relative to its kinematical and dynamical requirements. Development of a robot capable of fast movements or high payloads is progressed by the analysis of dynamic characteristics, DOF positioning, actuator selection, structure of links, and so on. This paper highlights the design of a robot manipulator scaled down from its final form, when it will passively be handled by a human for man-machine cooperation. The requirements of the system include its having 6-DOF and the capacity for a high payload in the condition of its maximum reach. The primary investigation factors are motion range, performance within the motion area, and reliability during the handling of heavy materials. Traditionally, the mechanical design of robots has been viewed as a problem of packaging motors and electronics into a reasonable structure. This process usually transpires with heavy reliance on designer experience. Not surprisingly, the traditional design process contains no formally defined rules for achieving desirable results, as there is little opportunity for quantitative feedback during the formative stages. This work primarily focuses on the selection of proper joint types and link lengths, considering a specific task type and motion requirements of the curtain wall installation process in the construction site based on the result of experiment of proto type system of this study.     

Stability and control aspects of flexible link robot manipulators during constrained motion tasks

The effect of robotic manipulator structural compliance on system stability and trajectory tracking performance and the compensation of this structural compliance has been the subject of a number of publications for the case of robotic manipulator noncontact task execution. The subject of this article is the examination of dynamics and stability issues of a robotic manipulator modeled with link structural flexibility during execution of a task that requires the robot tip to contact fixed rigid objects in the work environment. The dynamic behavior of a general n degree of freedom flexible link manipulator is investigated with a previously proposed nonlinear computed torque constrained motion control applied, computed based on the rigid link equations of motion. Through the use of techniques from the theory of singular perturbations, the analysis of the system stability is investigated by examining the stability of the “slow” and “fast” subsystem dynamics. The conditions under which the fast subsystem dynamics exhibit a stable response are examined. It is shown that if certain conditions are satisfied a control based on only the rigid link equations of motion will lead to asymptotic trajectory tracking of the desired generalized position and force trajectories during constrained motion. Experiments reported here have been carried out to investigate the performance of the nonlinear computed torque control law during constrained motion of the manipulator. While based only on the rigid link equations of motion, experimental results confirm that high-frequency structural link modes, exhibited in the response of the robot, are asymptotically stable and do not destabilize the slow subsystem dynamics, leading to asymptotic trajectory tracking of the overall system. © 1992 John Wiley & Sons, Inc.