Modified PID Control of a Single-Link Flexible Robot

The use of flexible links in robots has become very common in different engineering fields. The issue of position control for flexible link manipulators has gained a lot of attention. Using the vibration signal originating from the motion of the flexible-link robot is one of the important methods used in controlling the tip position of the single-link arms. Compared with the common methods for controlling the base of the flexible arm, vibration feedback can improve the use of the flexible-link robot systems. In this paper a modified PID control (MPID) is proposed which depends only on vibration feedback to improve the response of the flexible arm without the massive need for measurements. The arm moves horizontally by a DC motor on its base while a tip payload is attached to the other end. A simulation for the system with both PD controller and the proposed MPID controller is performed. An experimental validation for the control of the single-link flexible arm is shown. The robustness of the proposed controller is examined by changing the loading condition at the tip of the flexible arm. The response results for the single-link flexible arm are presented with both the PI and MPID controller used. A study of the stability of the proposed MPID is carried out.     

Dynamic Rolling-Walk Motion by the Limb Mechanism Robot ASTERISK

New dynamic rolling-walk motion for a multi-legged robot with error compensation is proposed. The motion is realized by using the isotropic leg arrangement and the dynamic center of mass control inspired by bipedal robots. By using the preview control of the zero moment point (ZMP) with a cart-table model based on the bipedal robot's technique, the robot's center of mass trajectory is planned for the dynamic motion. The resolved momentum control for manipulating the multi-links robot as a single mass model is also implemented in the system to maintain the stability of the robot. In the new dynamic rolling-walk motion, the robot switches between the two-leg supporting phase and three-leg supporting phase to achieve dynamic motion with the preview control of the ZMP and resolved momentum control as dynamic motion controllers. The authors analyzed the motion and confirmed the feasibility in the Open Dynamics Engine before testing the motion with an actual robot. Due to the difficulties of controlling the ZMP during the two-leg supporting phase, the authors implemented error compensation by using a gyro sensor and compared the results.     

A programming environment for real-time control of distributed multiple robotic systems

In recent years there has been great interest in robot software control architectures. However, although many interesting solutions have been presented, most of the research problems tackled related to a single robot perception, navigation and action in everyday environments. Instead, most of the practical applications of mobile robotics for service tasks in civilian environments consist of systems composed of multiple robots communicating with each other, with external sensing and actuating devices, and with external supervising workstations. RoboCup offers a great opportunity to deal with this problem. In fact the software architecture of a robot soccer player must allow successful intra-robot integration of the different activities (visual perception, path planning, strategy planning, motion control, etc.) spanning many different types of representation (raw sensor data, images, symbolic plans, etc.) and it must also guarantee successful inter-robot integration by supporting communication and cooperation. This paper focuses on this problem, presenting ETHNOS-IV - a programming environment for the design of a real-time control system composed of different robots, devices and external supervising or control stations - which has been successfully used within the Italian ART robot team in the RoboCup-99 competition. ETHNOS provides support from three main point of views which will be addressed in detail: inter-robot and intra-robot communication, realtime task scheduling, and software engineering and code reuse. Experimental results illustrating the advantages of this approach will also be presented.     

Distributed Telerobotics System Based on Common Object Request Broker Architecture

This paper proposes using CORBA as communication architecture to integrate network-distributed software and robotic systems in support systems for the aged or disabled. The proposed method keeps system costs low and expands availability. Its high scaling and inter-operating ability allows clients and server objects that are written in different languages, run in different operating systems, and connected to different networks to inter-operate. It also enables the system to be extended and integrated with other technologies and applications distributed over the Internet. Based on CORBA, we developed hardware base including a robot arm and an omnidirectional mobile robot and application servers including a task-level robot arm control server, live feedback image server, mobile robot control server and iGPS server. By remotely controlling mobile robot to cooperate with the robot arm, the caregivers or family member can use the developed system for some basic services to the aged or disabled.     

Investigations on the Hybrid Tracking Control of an Underactuated Autonomous Underwater Robot

The problem of trajectory tracking control of an underactuated autonomous underwater robot (AUR) in a three-dimensional (3-D) space is investigated in this paper. The control of an underactuated robot is different from fully actuated robots in many aspects. In particular, these robot systems do not satisfy Brockett's necessary condition for feedback stabilization and no continuous time-invariant state feedback control law exists that makes a specified equilibrium of the closed-loop system asymptotically stable. The uncertainty of hydrodynamic parameters, along with the coupled, nonlinear dynamics of the underwater robot, also makes the navigation and tracking control a difficult task. The proposed hybrid control law is developed by combining sliding mode control (SMC) and classical proportional–integral–derivative (PID) control methods to reduce the tracking errors arising out of disturbances, as well as variations in vehicle parameters like buoyancy. Here, a trajectory planner computes the body-fixed linear and angular velocities, as well as vehicle orientations corresponding to a given 3-D inertial trajectory, which yields a feasible 6-d.o.f. trajectory. This trajectory is used to compute the control signals for the three available controllable inputs by the hybrid controller. A supervisory controller is used to switch between the SMC and PID control as per a predefined switching law. The switching function parameters are optimized using Taguchi design techniques. The effectiveness and performance of the proposed controller is investigated by comparing numerically with classical SMC and traditional linear control systems in the presence of disturbances. Numerical simulations using the full set of nonlinear equations of motion show that the controller does quite well in dealing with the plant nonlinearity and parameter uncertainties for trajectory tracking. The proposed controller response shows less tracking error without the usually present control chattering. Some practical features of this control law are also discussed.     

自主柔性变形蛇形机器人控制系统设计

针对搜救机器人对多信息获取与处理、远程监控与运动控制的实时高性能需求,设计了以ARM微处理器STM32为核心、多传感器融合的自主柔性变形蛇形机器人控制系统,实现了机器人的远程监控与运动控制、多传感器环境信息采集等功能。整个控制系统具有良好的扩展性、硬件可裁剪性。通过模拟灾难废墟场景实验,结果表明：蛇形机器人控制系统可实现多信息的实时准确无线通信,在不同的环境中,具有良好的多步态运动稳定性和自主移动性能。     

基于强跟踪滤波的机器人运动轨迹控制系统设计

机器人运动信息采集的抗噪性较差,导致系统运动轨迹与实际轨迹不符,轨迹控制效果较差。因此提出基于强跟踪滤波的机器人运动轨迹控制系统设计。系统通过软硬件协同工作,实时控制机器人轨迹。采用IPM电机驱动控制系统硬件结构,根据指令和感知信息,采用多CPU结构控制方式,控制一个机器人关节运动。使用PCI9052接口控制PCI-485接口卡,实现了上下位机之间通讯。以TMS32OF240XDS为核心,设计DSP控制器,完全分离程序空间与数据空间。在软件设计方面,通过CAN-TTLG单片机光隔离超远程驱动器,使系统具有一定抗噪能力。构建机器人运动方程,引入强跟踪滤波弱化因子,计算运动轨迹偏差,并对机器人运动控制进行重力补偿,由此设计轨迹控制流程,完成机器人运动轨迹控制系统设计。实验结果表明,该系统运动轨迹与实际轨迹相符,且轨迹控制效率较好,具有良好控制效果。     

Adaptive control of free-floating space robots in Cartesian coordinates

An adaptive control scheme is proposed for the end-effector trajectory tracking control of free-floating space robots. In order to cope with the nonlinear parameterization problem of the dynamic model of the free-floating space robot system, the system is modeled as an extended robot which is composed of a pseudo-arm representing the base motions and a real robot arm. An on-line estimation of the unknown parameters along with a computed-torque controller is used to track the desired trajectory. The proposed control scheme does not require measurement of the accelerations of the base and the real robot arm. A two-link planar space robot system is simulated to illustrate the validity and effectiveness of the proposed control scheme.     

城市燃气管道检测机器人测控系统研究与发展现状

检测与控制系统分别用于城市燃气管道检测机器人在管道内的缺陷检测和运动控制,是城市燃气管道检测机器人核心部分.综述了国内外城市燃气管道检测机器人测控系统研究和发展现状;论述了城市燃气管道检测机器人测控系统发展过程;结合各种燃气管道检测机器人系统构成示意图及测控系统构架图,阐述了测控系统工作原理,重点分析了基于通信线缆通信和基于无线通信的监督式测控系统;指出了未来城市燃气管道检测机器人测控系统的研究方向.     

Control System Design for an Upper-Limb Rehabilitation Robot

Control system implementation is one of the major difficulties in rehabilitation robot design. The purpose of our study is to present newly developed control strategies for an upper-limb rehabilitation robot. The Barrett WAM Arm manipulator is used as the main hardware platform for the functional recovery training of the past-stroke patient. Passive and active recovery training have been implemented on the WAM Arm. A fuzzy-based PD position control strategy is proposed for the passive recovery exercise to control the WAM Arm stably and smoothly to stretch the impaired limb to move along predefined trajectories. An adaptive impedance force controller is employed in the active motion mode in which a fuzzy logic regulator is used to adjust the desired impedance between the robot and impaired limb to generate adaptive force in agreement with the change of the impaired limb's muscle strength. In order to evaluate the change of the impaired limb's muscle power, the impaired limb's mechanical impedance parameters as an objective evaluation index is estimated online by using a recursive least-squares algorithm with an adaptive forgetting factor. Experimental results demonstrate the effectiveness and potential of the proposed control strategies.     

Heavy material handling by cooperative robot control

Multifingered dextrous robot hands can perform more complex tasks than simpler end effectors. Teleoperation, in which a robot mimics the motion of a remote operator, provides a convenient method for controlling these robot hands. Damage to the object being manipulated by the robot hand may result in the case of open-loop control if there is no force-feedback sensation to the operator from the robot hand. The need arises for new actuator technology to provide force feedback to the hand master. These actuators have to meet the tight space and light weight requirements of a dextrous master. One candidate is the shape memory alloy (SMA) actuator. SMAs, such as Nitinol, are materials with a unique 'mechanical memory' and high force/weight ratio. A prototype SMA actuator and its hardware interface were designed and tested. Results showed that the actuator met the space and weight limitations of the master (Exos DHM?) and provided adequate reactive force feedback to the operator. However, the actuator had a low bandwidth of operation, due to relatively slow engagement and disengagement motions. This makes it unusable in real-time control situations.     

异构多机器人协作系统研究进展

异构多机器人系统可以发挥单一结构机器人在某个领域的优点而达到整体的最优配置,机器人的功能和接口协议对协作系统影响很大.IGRS协议是我国在信息设备协作领域中惟一的国际标准,为异构多机器人协作提供了有效的支持.对国内外相关研究进行系统地归纳和总结,找出需要解决的问题,并在课题组研制的多种机器人平台上,从3个方面阐述了基于IGRS协议的异构多机器人协作系统:异构机器人的定位、通信以及感知方案;异构机器人协商策略和分组方案;机器人的功能分类和规划,提出了细粒度可控的任务委托分配方案.     

基于大数据聚类的智能探测机器人运动控制系统设计

为了减小智能探测机器人运动轨迹误差,实现精准控制,提高智能探测机器人运动控制效率,设计基于大数据聚类的智能探测机器人运动控制系统;采用TMS320LF2407A主控芯片,集成650 V功率管,在电感电流断续模式下工作,提供系统驱动能量,设置光电耦合器,处理控制信号发射,调整控制电路内部电流关系;选用6ES7214-1AG40-0XB0控制器以及信号和通信模块扩展,控制机器人运动轨迹,结合内部驱动装置,整合运动数据信息进行存储,实现运动控制系统硬件结构设计;通过调节程序开始数据,结合内部脉冲数据,构建软件平台管理模块,获取机器人运动轨迹数据;采用大数据聚类技术,建立控制系统大数据分布结构模型,模拟非线性时变LFM控制信号,提取特征并聚类运动轨迹数据,获取精准运动轨迹数据,减少运动轨迹偏差程度,完成运动控制系统软件设计;实验结果表明,基于大数据聚类的运动控制系统的运动轨迹误差较小,能够有效实现精准控制,提高运动控制效率.     

电动并联六轮足机器人的运动驱动与多模态控制方法

提出一种并联六轮足移动机器人.该机器人设有多模式Stewart型腿结构,其负载能力大,集成了轮式运动和足式运动的优点,可实现足式、轮式、轮足复合式运动.首先,阐述了机器人设计思路,对电动并联六轮足机器人的硬件系统和控制系统进行设计.其次,针对足式运动模式,设计了一套完整的足式"三角"步态和稳定行走算法,该算法可降低足端与地面之间的垂直方向冲击,防止足式运动拖腿或打滑;针对轮式运动模式,设计并介绍了6轮协同控制和轮式协同转向原理;针对轮足复合式运动模式,介绍了变高度、变支撑面、变轮距、主动隔振控制原理,重点分析了主动隔振控制和变轮距控制,可实现主动隔振及姿态平稳控制,提高了机器人在崎岖颠簸地形下的轮足复合式运动的稳定性.最后,对电动并联六轮足机器人的足式、轮式、轮足复合式运动模式进行实验,实验结果验证了本文提出的并联六轮足移动机器人设计的可行性和各运动模式下驱动与控制算法的有效性.     

软实时环境下机器人运动学逆解研究

为有效抑制串联机构的末端振动,使机器人运动系统的运行更加平滑,设计了以PC104为硬件基础、在RTLinux上进行二次软件开发的机器人控制系统。它通过PCI/ISA总线连接上位机和底层硬件接口电路,以控制伺服电机。分别研究了机器人系统的模型,以及在这一软实时系统上采用反变换法+Pieper方法求解机器人的逆运动学问题。通过比较工业机器人在伺服控制、板卡控制和软件控制三种模式下的运动性能,验证了软件方式的优越性,以及其在运动控制领域中的应用价值。     

基于STFT的微创手术机器人运动控制系统设计

针对微创手术机器人运动过程受到信号干扰而导致机器入主从臂控制效果差、控制精度较低的问题,提出了基于STFT的微创手术机器人运动控制系统设计;主控制器通过蓝牙的无线传输方式与主机连接,采用I/O口模拟SCI硬件流控方式,实现MCU与蓝牙通信,为系统提供基础数据;设计时钟基准电路的并联振荡模式,方便失控程序重启;根据运动控制器结构,设计预留模数转换接口,并对机器人主从操作臂展开详细分析;使用基于STFT短时傅里叶变换方法抑制外界干扰,在LM629运动控制专用集成芯片支持下设计控制流程,完成基于STFT的微创手术机器人运动控制系统设计;设计对比实验,结果表明该系统与期望主臂运动轨迹的终点坐标(10 mm,-35 mm,45 mm)和从臂运动轨迹的终点坐标(18 mm,-45 mm,25 mm)一致,能够精准控制微创手术机器人运动精度,为医学手术智能化开展提供设备支持.     

基于ROS平台的智能车运动线控系统设计及实现

针对无人操作智能车辆依靠特定硬件平台等问题,提出了一种基于ROS平台的无人小车的低成本运动线控系统解决方案。该方案基于上位机和下位机的控制结构,上位机代替驾驶员的功能负责决策,下位机负责执行命令。重点给出了上位机、下位机以及上下位机通信的软硬件设计思路和方法,并在ROS平台上使用了Modbus通信,构建了一个结构相对简单、功能可行的低速的无人车运动控制系统。该解决方案的所有软件都是开源或可自行设计的,为更多的研究人员以更低成本研究无人智能车提供了参考。实验结果表明,该运动控制系统解决方案是可行并且有效的,未来可应用于园区、学校等地的小型无人车的控制系统设计。     

双臂搬运机器人反应式导航控制系统设计

为增强双臂搬运机器人在作业任务过程中的行进避障能力,使其运动行为得到连续有效控制,设计双臂搬运机器人的反应式导航控制系统。根据单片机与电机电路的连接形式,选择合适的ARM微处理器元件与PIC单片机结构,再联合HN-9移动平台、智能导航平台、ROS操作平台,完善反应式导航子模块的运行能力,实现控制系统的硬件单元设计。求取绝对位姿向量、相对位姿向量的计算结果,以此作为自变量系数,确定速度雅可比指标,并推断得出动力学递推表达式,完成对双臂搬运机器人的协调控制,联合相关硬件应用结构,实现双臂搬运机器人反应式导航控制系统的设计。对比实验结果：反应式导航控制系统可使机器人准确躲避行进障碍物,且躲避过程中机器人完成作业任务的能力不会受到影响,符合连续有效控制机器人搬运行为的实际应用需求。     

Motion coordination and reactive control of autonomous multi-manipulator systems

The emerging field of service robots demands new systems with increased flexibility. The flexibility of a robot system can be increased in many different ways. Mobile manipulation—the coordinated use of manipulation capabilities and mobility—is an approach to increase robots flexibility with regard to their motion capabilities. Most mobile manipulators that are currently under development use a single arm on a mobile platform. The use of a two-arm manipulator system allows increased manipulation capabilities, especially when large, heavy, or non-rigid objects must be manipulated. This article is concerned with motion control for mobile two-arm systems. These systems require new schemes for motion coordination and control. A coordination scheme called transparent coordination is presented that allows for an arbitrary number of manipulators on a mobile platform. Furthermore, a reactive control scheme is proposed to enable the platform to support sensor-guided manipulator motion. Finally, this article introduces a collision avoidance scheme for mobile two-arm robots. This scheme surveys the vehicle motion to avoid platform collisions and arm collisions caused by self-motion of the robot. © 1996 John Wiley & Sons, Inc.     

基于D-H法的农业采摘机器人运动协作控制系统设计

为提升农业采摘机器人运动协作控制性能,降低机器人碰撞概率,利用D-H法优化设计机器人运动协作控制系统。改装位置、力矩以及碰撞传感器设备,优化运动协作控制器与驱动器,调整系统通信模块结构,完成硬件系统的优化。利用D-H法构建农业采摘机器人数学模型,在该模型下,利用传感器设备实现机器人实时位姿的量化描述,通过机器人采摘流程的模拟,分配机器人运动协作任务,从位置和姿态等多个方面,确定运动协作控制目标,经过受力分析求解机器人实际作用力,最终通过控制量的计算,实现农业采摘机器人的运动协作控制功能。通过系统测试实验得出结论：与传统控制系统相比,机器人位置、姿态角和作用力的控制误差分别降低了约40mm、0.2°和1.2N,在优化设计系统控制下,机器人的碰撞次数得到明显降低。