在人机协作中基于动量观测和优化算法的全机械臂单点接触信息实时估计

针对协作型机器人,提出了一种依据机器人控制与运动状态信息,基于动量观测与优化算法相结合的全机械臂单点接触信息实时估计方法.该方法将接触位置估计问题转化为优化算法有界搜索问题,搜索范围由动量观测方法确定的接触臂长度确定,两种方法的结合保证了估计的精度和实时性.基于UR机械臂实验平台的仿真与实验结果表明,本文方法能够实时、准确地估计除第1关节以外首次发生接触的机械臂任意位置处的力和位置信息.本研究可以在不借助传感器的情况下实现机械臂对外力的感知.     

Mechanical design and control of inflatable robotic arms for high positioning accuracy

In recent years, inflatable robotic arms have been developed so that physical contact with humans and working environments could be performed safety. In industry, there is a growing demand for safe industrial robots to collaborate with people and work in various environments. In general, however, the positioning accuracy of inflatable robotic arms has not been discussed. This paper proposes an inflatable link structure and a non-inflatable joint structure that could realize a high positioning accuracy for such robotic arms. This paper experimentally demonstrates that these structures can improve positioning accuracy. In addition to these structures, the joint torque characteristics of the inflatable robotic arms were investigated. In order to perform accurate motion control, a visual feedback control method was introduced for inflatable robotic arms. The mechanism and control system used in this paper can improve the positioning accuracy performance of inflatable robots. A 2-DOF inflatable robotic arm and a camera system were found to be able to achieve a high positioning accuracy (i.e. less than 1 mm).     

Design and Implementation of Electronic System and Computer Control of an Indexing Table and Quality Control Unit

Capability and meanwhile simplicity have stupendously expanded the area of application of linear controllers in the industrial applications, particularly the control of robotic arms, and other automated systems. The ultimate goal to accomplish this project is to show this capability in the frame of movement control of the arm of a quality control unit (side device), which forms a part of an automatic cell together with an indexing table. The fact that the existence of the gearbox, dramatically decreases the effects of non-linear dynamic of the arm to linear dynamic of the DC motor, justifies the idea of design and implementation a linear controller like Lead-Lag to control the quality control arm. Of course, we need to apply some other equipment like DC motor torque control system, sensors, and related interface circuits. In this article, it will be explained how the above goal will be accomplished by linear identification of the system with the method of step response identification and then digital implementation of the linear controller in computer and application of the arm motor torque control (Karami, J., Roohi, A., Design and implementation of electronic system and computer control of an indexing table and quality control unit. 2006 IEEE/ASME International Conference on Mechatronics and Embedded Systems and Applications, 2006).     

多机械臂抓取物的内力不变性

对多机械臂抓取物的受力分析表明，现有物体内力的定义不具备欧几里德直射变换下的不变性，导致模型化的内力与物体实际所受内力不符，基于这样的定义进行载荷分配并实施协调控制会造成体或机械臂的损坏。     

Cost-efficient drilling using industrial robots with high-bandwidth force feedback

Here we present a method for high-precision drilling using an industrial robot with high-bandwidth force feedback, which is used for building up pressure to clamp-up an end-effector to the work-piece surface prior to drilling. The focus is to eliminate the sliding movement (skating) of the end-effector during the clamp-up of the end-effector to the work-piece surface, an undesired effect that is due to the comparatively low mechanical stiffness of typical serial industrial robots. This compliance also makes the robot deflect due to the cutting forces, resulting in poor hole position accuracy and to some extent in poor hole quality. Recently, functionality for high-bandwidth force control has found its way into industrial robot control systems. This could potentially open up the possibility for robotic drilling systems with improved performance, using only standard systems without excessive extra hardware and calibration techniques. Instead of automation with expensive fixtures and precise machinery, our approach was to make use of standard low-cost robot equipment in combination with sensor feedback. The resulting sliding suppression control results in greatly improved hole positioning and quality. The conceptual idea behind the force control is useful also in many other robotic applications requiring external sensor feedback control.     

Low cost dual axis micro force sensor for robotic manipulations

A multi-dimensional force measurement device often plays an important role in micro robotic manipulations. Due to the high level required accuracy and physical dimensions of the sensors, they are normally fabricated through a series of MEMS process which makes the sensors not only prohibitive but also vulnerable to an excessive loading operation environment. In this article, an inexpensive force measurement using strain gauges is developed and tested. Combining a mechanical structure optimization and signal processing technique, the present work provides a fairly precise force measurement in sub-micron Newton scale. In addition, the developed concept is expanded to a dual axis force measurement which extends its application to the micro particle robotic manipulations.     

基于精英策略粒子群算法机械臂逆运动求解

多关节机械臂空间姿态控制研究中,逆运动分析是控制的基础,由于多关节机械臂逆运动求解问题较为复杂,对其求解结果优劣性的判别比较困难.为了解决传统关节变量算法在求解过程中收敛精度不高、局部最优解过多的问题,利用精英策略搜索粒子种群中的优质粒子,提高了算法整体适应度值,避免求解陷入局部最优解.仿真实验结果表明,基于精英策略多目标粒子群算法(ETMOPSO)提高了机械臂空间姿态的求解精度,为多关节机械臂空间姿态控制提供了一种研究思路.     

Neural-Network-Based Contact Force Observers for Haptic Applications

In the majority of robotic and haptic applications, including manipulation and human-robot interaction, contact force needs to be monitored and controlled. Transparent implementation of bilateral teleoperation or haptic controllers necessitates the exchange of operator and environment contact forces. This requires the use of expensive commercially available force/torque sensors, which are rather bulky, are vulnerable to impact forces, and increase system inertia and compliance. An alternative solution is the use of dynamic force observers, which estimate external forces using system dynamic model. However, due to the uncertainties in system dynamic structure and parameters, these model-based observers do not produce accurate force estimates, and often create a dynamic lag that may cause bandwidth limitation and instability. This paper proposes two neural-network-based force/torque observers that do not require a system dynamic model. The observers can estimate human hand force and environment contact force with up to 98.3% accuracy in the sense of mean-square error, and with negligible dynamic lag. The performance of the proposed observers are extensively analyzed in separate human-robot and robot-environment experimental settings, and in a two-channel bilateral teleoperation control loop with multiple runs with two Planar Twin-Pantograph haptic devices     

基于多信息算法融合的电子元件精准装配研究

机器人是现代化工业制造与生产的重要装备之一。随着市场需求向小批量、多品种和柔性化方向快速发展,基于多信息融合的机器人协作系统将为高端精密制造产业赋能。该研究着眼于精密电子元件装配领域,聚焦手眼系统的精准对位和精密插装技术,通过建立待插元件与非均质薄板的接触状态模型,分析其双重位移融合的力位运动特性,并结合视觉检测与跟踪技术,提出一种融合视觉、力觉和编码器信息的复合型控制算法。基于电子元件装配平台,该研究进行了元件插装对比实验和信息融合算法的装配实验,结果表明,对齐阶段的定位精度在 0.185 pixels 以内,装配阶段的接触状态判定和调节算法保障了元件与插槽的安全有效装配。     

Measurement and analysis of structural dynamics properties of robotic joint transmission system

The flexibility of a robotic manipulator is considered an important factor, especially the joint compliance for improving the accuracy and operating speed of a robot application. In this article, two methods are employed to identify the structural dynamic characteristics of each joint transmission system of an ITRI-U type robot. The driving system of each joint is modeled as a mass-spring-damper mechanism that has a second-order dynamic mathematical equation. Then, the response experiments of hammer impact excitation and motor driving actuation are done and the difference between them compared. Those are used to simulate two different operation situations, the robot colliding with the environment and the discontinuing dynamic operation impacts. The system's parameters of each joint axis are obtained by the system identification technique. From the experimental results, the angular error of the motor shaft can be compensated by the control gain of the motor controller. However, the small damping ratio of the robotic mechanism limits the magnitude of servo gain. If the servo gain increases, the robot arm has oscillation phenomenon during dynamic operation. In addition, the error due to joint elasticity cannot be overcome by the current industrial robotic controller. Therefore, a suitable controller should be designed to compensate the dynamic effects of joint compliance with the identified parameters.     

Development of a system for robotic deburring

Relatively crude robotic deburring has been accomplished through the detailed programming of the edge contour and the provision of significant passive compliance to compensate for positional errors. In precision deburring, the uncertainties in edge position relative to the tool location may be too great to allow a sufficiently uniform chamfer to be obtained using passive compliance alone. In addition, the costs associated with the detailed path programming can represent a significant fraction of the cost of deburring. This paper discusses the development of a robotic deburring system which provides for simultaneous edge following and force control. An AdeptOne robotic manipulator has been interfaced with an instrumented remote center of compliance manipulator to provide a system which tracks an edge at a controlled force level which can be specified by the operator.     

Determining maximum payloads for cooperating robots under time-optimal control

This work presents an algorithm which evaluates the dynamic performance limit of a cooperating robotic system using movements planned for minimum time. Minimum-time movements characteristically require that a set of motors in the robot be driven at their maximum torque throughout the motion. These movements are limited by the combination of motor performance, mechanical advantage of the kinematic chain, and the location of the start and goal positions. By increasing the payload for a motion until a minimum-time solution is no longer feasible the payload limit of the system for the associated path is obtained. To illustrate the algorithm a detailed analysis of a robotic arm developed at Odetics Inc. is presented. The analysis includes numerical results for cooperating Odetics robotic arms using their maximum payload under time-optimal control. Furthermore, the maximum payload for the cooperating robotic system to perform the same motion with a 1 sec time constraint is determined.     

Design and performance evaluation of an actively compliant underwater manipulator for full-ocean depth

An underwater manipulator is described that can exhibit a wide range of compliance through a combination of mechanical design and software control and its performance characterized. The manipulator has been used in conjunction with the JASON Remotely Operated Vehicle at full-ocean depth. The major goal of the design was to produce a manipulator that can actively control the interaction forces with the work task in the hostile deep-ocean environment. The manipulator's performance has been characterized in the lab and its overall operational utility has been confirmed during tests to depths of approximately 4000 meters, including an archaeological excavation at 700 meters depth in the Mediterranean. The manipulator uses high performance brushless DC servomotors driving the joints though low-friction, zero-backlash reductions of moderate ratio consisting of cables and pulleys. Each joint is highly backdriveable and has a large range of rotation. This approach permits a variety of force control schemes such as impedance control to be implemented with no sensors other than the displacement sensors integrated with the brushless motor. It also permits high-quality torque servomechanisms to be directly implemented. This article outlines the design and illustrates the performance of a single joint in terms of friction, stiffness, and in implementing variable compliance and as a closed-loop torque servo.     

基于细菌觅食算法的嵌入式机械臂角度控制器设计

进行机械臂角度控制器设计过程中,为提高机器人机械臂灵活性,降低关节角度控制误差,设计一种细菌觅食算法的嵌入式机械臂角度控制器。首先,构建机械臂动力学模型以获取机械臂的柔性特征及其关节位置,根据获取的信息确定角度控制器的硬件逻辑结构和算法。然后,使用ARM微处理器嵌入式操作系统,设计包含移动控制终端和机械臂控制端的控制器硬件结构。最后,采用细菌觅食算法优化控制器参数,并实现代码完成机器人机械臂角度的精准跟踪控制。仿真分析结果表明:所提方法具有较高的位姿跟踪精度、角度控制误差小、稳定性强,能够保证机械臂关节角度无超调,具有极高的机器工程应用价值。     

Compact modeling of spatial continuum robotic arms towards real-time control

This paper presents a compact modeling approach of continuum robotic arms, with limited computations for faster numerical calculations in real-time implementations. It is assumed that the arm includes a backbone made of elastic rods, and the Cosserat rod theory is simplified for numerically faster modeling. The time-taking boundary-value problem (BVP) is detailed, and some numerical methods are introduced to solve the developed equations of modeling. Next, based on physical intuition, a fast and stable method is proposed to solve the BVP, as a moment-based approach. Also, a method to cancel some numerical integration errors with the least required computations and numerical efforts is presented. Next, a Jacobian-based control of multi-segment continuum robotic arms is developed. Finally, this procedure is experimentally verified to show the precision of proposed modeling approach and also to reveal the importance of faster solutions for real-time control.     

多感知机器人夹持器设计

介绍了一种具有力觉、触觉和位置信息的机器人夹持器设计。讨论了力觉传感器、触觉传感器和位置传感器的设计与实现，概述了夹持器的机械结构及其控制系统设计。     

On the design and simulation-based validation of an active compliance law for multi-arm robots

A special active compliance law is presented as the feedback element in a non-master/slave (i.e. symmetric) coordination strategy with explicit force distribution for robots with multiple cooperating arms. The method used to design the compliance controller comprise a structural design phase and dynamics design phase. The proposed controller structure simplifies the design problem as it maps the multivariate system onto two decoupled SISO loops with PI controllers describing internal and external compliance behavior. The conditions for the validity of this conceptual system model are discussed and the significance of task parameters such as grasp configuration, force distribution law and mechanical compliance values for the controller structure is explored. The dynamic behavior of internal and external compliance is determined in the second design phase by the choice of gain and integral action time of the respective controllers. An example shows the applicability of classical SISO control system design tools such as the root locus technique. The validity of the design method has been verified by means of the multi-arm robot simulation program MAROSIM, which is also presented in the paper.     

Sensing mechanism for estimation of the physical properties of an object avoiding failure of the sensors

Active sensing, in which a robot pushes an object and senses the reaction force or joint angle by means of the force sensor at the point of the contact or on the joint, is one of the effective approaches to estimate the physical properties of an object, such as its compliance. A compliant joint driven by elastic actuators has an advantage over a rigid joint driven by a motor with a high gear ratio in that it absorbs the reaction force, and thus avoids any joint damage during active sensing. However, this approach is not suitable for either rigid joint or a compliant joint because the sensors attached to the contact point and the joint tend to break, owing to iterative contact or an excessive force. Here, this paper adopts a one-degree-of-freedom joint mechanism driven by elastic pneumatic actuators, and focuses on the passivity of the elastic pneumatic actuator, in which the pressure is changed when force is applied, after which it is deformed. By utilizing the passivity of the actuators under a number of conditions, this paper derives multiple regression models of the force and the angle, using the pressures before and after force is applied to the joint mechanism. Experimental results present that the contact information can be estimated from the pressure values and that the joint mechanism can detect the elasticity of an object using the regression models. We also observe the range of the elasticity of the object by tuning the joint compliance. This approach provides a robot hand that can estimate the contact information, including the force and joint displacement, avoiding the failure of the sensors.     

RSSS-II 脊柱手术机器人系统开发及其实验研究

手术机器人应用于脊柱手术中,辅助医生完成脊柱手术中钉道定位、钻钉道等操作,有助于降低医生工作强度,保证了手术操作的精确性、稳定性和安全性.文章针对椎弓根钉内固定术,设计研制了脊柱手术辅机器人系统RSSS-Ⅱ.首先,从脊柱手术的临床需求出发,充分考虑术中安全性、手术区域覆盖范围、患者术中摆位以及对机器人占地空间等多方面因素,设计六自由度串联式手术机械臂以及力反馈钻骨装置.其次,以椎弓根钉内固定术中准确定位为目的,对机器人导航定位所涉及的关键技术展开研究,构建了图像导航定位系统.最后,通过精度测试实验和离体样本骨实验,对关键技术及系统的精度、安全性等进行原理性验证.实验结果显示,脊柱手术机器人系统RSSS-Ⅱ能满足手术对精度的要求.     

一种苹果采摘机器人关节伺服控制系统设计及仿真

当前,苹果采摘机器人大多选用工业机械臂,关节控制采用电机加减速装置来提高控制精度、增大驱动力矩,这无疑会增加系统的复杂性、成本以及降低系统控制性能;为改善这种情况,给出一种基于直流力矩电动机加谐波减速器的苹果采摘机器人关节控制方案,系统可大大减小驱动机构体积,提高系统刚性,实现低速稳定的精准控制;MATLAB环境下仿真结果表明,在0.5°和60°的阶跃给定下,系统超调量和稳态误差均为0;在幅值为5°,频率为3.14rad/s正弦信号输入下,系统输出能够完全跟随输入;系统控制精度达到了苹果采摘要求,为后续简化采摘机器人机械臂结构、甚至实现直接驱动提供了有力的理论支持。