Design of Robust Controller for Flexible Joint Robot with Nonlinear Friction Characteristics

A robust controller method for flexible joint robot considering the effect caused by nonlinear friction was presented.The nonlinear friction was denoted as inverse additive output uncertainty relative to the nominal model in our work,based on which the describing function was analyzed in frequency domain,and the weighting function of nonlinear friction was further calculated as well. By combining the friction uncertainty,the mixed sensitivity H∞optimization was proposed as the benchmark for controller design, which also leaded to good performance of robustness. Furthermore,unstructured perturbation to the system was analyzed so that the stability was guaranteed. Simulation results show that the proposed controller can provide excellent tracking and regulation performance.

Dynamic surface control-backstepping based impedance control for 5-DOF flexible joint robots

A new impedance controller based on the dynamic surface control-backstepping technique to actualize the anticipant dynamic relationship between the motion of end-effector and the external torques was presented.Comparing with the traditional backstepping method that has "explosion of terms" problem,the new proposed control system is a combination of the dynamic surface control technique and the backstepping.The dynamic surface control(DSC) technique can resolve the "explosion of terms" problem that is caused by differential coefficient calculation in the model,and the problem can bring a complexity that will cause the backstepping method hardly to be applied to the practical application,especially to the multi-joint robot.Finally,the validity of the method was proved in the laboratory environment that was set up on the 5-DOF(degree of freedom) flexible joint robot.Tracking errors of DSC-backstepping impedance control that were 2.0 and 1.5 mm are better than those of backstepping impedance control which were 3.5 and 2.5 mm in directions X,Y in free space,respectively.And the anticipant Cartesian impedance behavior and compliant behavior were achieved successfully as depicted theoretically.

Driving Torque Reduction in Linkage Mechanisms Using Joint Compliance for Robot Head

The conventional linkage mechanisms with compliant joint have been widely studied and implemented for increasing the adaptability of the mechanism to external contacts. However, the analysis of how compliant joints in linkage mechanism can reduce the energy consumption isn＇t still studied deeply. In a mobile service robot head, the actions of blinking the eyes and moving the eyeballs are realized by the planar linkage mechanism respectively. Therefore, minimizing the driving torques through motion trajectories for the linkage mechanism, which will be beneficial to extend the working time for mobile service robots. The dynamic modeling of the linkage mechanism with springs-loaded compliant joint is established. An optimization procedure for obtaining the optimal parameters of springs is proposed for minimizing the max value of driving torques within a range of desired operating conditions. The Simulations prove that the linkage mechanism with compliant joints can effectively reduce the driving torques, and reduce the energy consumption consequently. The framework can also be applied in other similar applications to reduce the driving torque and save energy. Compared with previous efforts, this is the first attempt that the linkage mechanism with complaint joint is applied in the robot head for reducing the driving torque.

Analysis of Robot Accuracy Assessed via its Joint Clearance by Virtual Prototyping Method

This paper discusses how joint clearance influences robot end effectorpositioning accuracy and a robot accuracy analysis approach based on a virtual prototype isproposed. First, a 5-DOF(Degree of freedom) neurosurgery robot was introduced. Then we built itsvirtual prototype, made movement planning and measured the manipulator tip accuracy, through whichthis robot accuracy portrait was obtained. Finally, in order to validate the robot accuracyanalysis approach which is based on a virtual prototype, the result was compared with that from amodel built by robot forward kinematics and robot differential kinematics. The robot accuracyanalysis approach presented in this paper gives a new way to enhance robot design quality , and helpto optimize the control and programming of the robot.

Research on Precision Assembly Robot's Joint Torque Control Based on Current Measurement

A set of new current sensing device is used to realize joint torque control based on current measurement in a precision assembly robot's third joint. The output torque's model of the joint's brnshless DC motor is founded. Disturbance factors and the compensated effect of the torque's closed loop based on current measurement are analyzed. Related simulations and experiments show that the system has good current tracking and anti-disturbances performance, which improve the force control performance of the robot in assembly.

Anti-Windup Control Strategy of Drive System for Humanoid Robot Arm Joint

To address the problems of torque limit and controller saturation in the control of robot arm joint,an anti-windup control strategy is proposed for a humanoid robot arm,which is based on the integral state prediction under the direct torque control system of brushless DC motor. First,the arm joint of the humanoid robot is modelled. Then the speed controller model and the influence of the initial value of the integral element on the system are analyzed. On the basis of the traditional antiwindup controller,an integral state estimator is set up. Under the condition of different load torques and the given speed,the integral steady-state value is estimated. Therefore the accumulation of the speed error terminates when the integrator reaches saturation. Then the predicted integral steady-state value is used as the initial value of the regulator to enter the linear region to make the system achieve the purpose of anti-windup. The simulation results demonstrate that the control strategy for the humanoid robot arm joint based on integral state prediction can play the role of anti-windup and suppress the overshoot of the system effectively. The system has a good dynamic performance.

Joint space compliance control for a hydraulic quadruped robot based on force feedback

In the realm of quadruped robot locomotion,compliance control is imperative to handle impacts when negotiating unstructured terrains.At the same time,kinematic tracking accuracy should be guaranteed during locomotion.To meet both demands,ajoint space compliance controller is designed,so that compliance can be achieved in stance phase while position tracking performance can be guaranteed in swing phase.Unlike operational space compliance control,the joint space compliance control method is easy to implement and does not depend on robot dynamics.As for each joint actuator,high performance force control is of great importance for compliance design.Therefore,a nonlinear PI controller based on feedback linearization is proposed for the hydraulic actuator force control.Besides,an outer position loop（compliance loop）is closed for each joint.Experiments are carried out to verify the force controller and compliance of the hydraulic actuator.The robot leg compliance is assessed by a virtual prototyping simulation.

Interval Type-2 Fuzzy PD Tracking Control of Flexible-Joint Robots

This paper develops a novel interval type-2 fuzzy Proportional-Derivative (PD) control scheme for electrically driven flexible-joint robots using the direct method of Lyapunov. The controller has a simple design in a decentralized structure. Compared to the previous controllers reported for the flexible-joint robots which use two control loops, it has a simpler structure using only one control loop. It guarantees stability and provides a good tracking performance. The controller considers the whole robotic system including the manipulator and motors by applying the voltage control strategy. Stability analysis is presented and the effectiveness of the proposed control approach is demonstrated by simulations using a three link flexible-joint robot driven by permanent magnet DC motors. Simulation results show that the interval type-2 fuzzy PD controller can handle external disturbance better than the type-1 fuzzy PD controller. In addition, it spends less control effort than the type-1 in order to deal with disturbance.

Real-time accurate hand path tracking and joint trajectory planning for industrial robots(Ⅰ)

Previously, researchers raised the accuracy for a robot′s hand to track a specified path in Car-tesian space mainly through increasing the number of knots on the path and the number of the path′s segments, which results in the heavier online computational burden for the robot controller. Aiming at overcoming this drawback, the authors propose a new kind of real-time accurate hand path tracking and joint trajectory planning method. Through selecting some extra knots on the specified hand path by a certain rule and introducing a sinusoidal function to the joint displacement equation of each segment, this method can greatly raise the path tracking accuracy of robot′s hand and does not change the number of the path′s segments. It also does not increase markedly the computational burden of robot controller. The result of simulation indicates that this method is very effective, and has important value in increasing the application of industrial robots.

基于Solidworks的重载机器人肩部的建模与静态分析

为了提高机器人的肩部有效控制能力,设计了一个165 kg重载6自由度机器人肩关节.通过设计一个谐波减速器和一对直齿齿轮以降低转速和提升转矩,利用齿轮与轴的配合完成肩关节在平面内的旋转.选择110AEA12020-SH3交流伺服电机、SHG-45-100谐波减速器以及6011和6016深沟球轴承进行肩部旋转关节旋转方案的设计,并利用有限元法对传动系统主要部件的静力学强度进行分析.结果表明,该肩部旋转关节旋转方案设计合理,轴承与齿轮的静力学性能满足实际应用需求.

一种基于根管预备的绳驱机器人设计与分析

该文设计一种应用于根管预备手术中绳驱机器人构型。电机转动输出连接软轴,软轴与绳索滚筒采用锥度插孔相连,可以实现输出轴方便快捷的拆卸,便于末端机构的高温消毒程序。采用绳索驱动实现驱动元件与执行元件的相对远距离布置,保证末端执行部件的较小尺寸,便于在口腔狭小空间中进行动作。对末端执行机构根管锉软轴进行变形分析,并利用相邻关节间绳索的反向拉缩进行运动的补偿,保证关节间运动的解耦。最后进行样机的制作并验证其基本运动与运动补偿具备可行性。

柔性多关节移动机器人非线性控制轨迹的二次模糊逼近

针对柔性多关节移动机器人在非线性控制轨迹下控制精准度不高的问题,提出一种非线性控制下的模糊逼近方法。建立机器人动力学模型,根据动力学特性设置矢量参数,对误差扰动动态修正。将矢量参数作为初始输入值,采用加权平均和乘积推理法,使得矢量符合自适应规律,通过模糊逼近函数对控制器的输出值实行状态逼近,直至符合初始设定值;凭借李亚普诺夫函数对控制输出值二次实施稳定模糊逼近,完成非线性轨迹控制。以B样条曲线轨迹为例做控制实验,实验数据证明:该二次逼近控制方法在非线性轨迹下的控制精准度较高,控制器输出力矩稳定,实用性能较强。

机理模型与集成学习混合驱动的机器人关节摩擦建模方法

机器人一体化关节广泛应用于医疗、协作机器人等领域,其摩擦特性是影响机器人性能的关键因素.为此,提出了一种机理模型与集成学习混合驱动的机器人关节摩擦建模方法,以提高模型精度.首先,综合考虑转速、负载等关节摩擦特性的影响因素及其周期波动特性,基于先验知识和物理分析分别建立了伺服电机与谐波减速器的参数化机理模型,描述摩擦特性的变化规律.然后,针对机理建模中因线性假设、忽略高阶项等产生的非线性残差,提出了基于eXtreme gradient boosting(XGBoost)的残差补偿模型建模方法,通过采用Boosting集成学习策略,提高残差补偿模型的泛化能力.同时,采用贝叶斯优化方法进行XGBoost模型的超参数寻优,以提高模型精度和训练效率.相比于传统的参数化机理模型,本文所提出的混合驱动模型具有更高精度.与反向传播神经网络、支持向量机、长短时记忆神经网络等多种典型方法的对比实验表明,本文所提出的基于XGBoost的残差补偿模型具有更强的特征提取能力,能够较好地预测强非线性的波动摩擦残差,有效地提高了整体模型的精度.

面向电流信息与模态分析的工业机器人关节振动求解研究

在工业机器人健康监测中,针对需采用振动传感器对机器人各关节逐一检测而引起测试成本剧增问题,提出一种基于电流信息与模态分析的关节振动求解方法,该方法可由关节电流经模态转换直接获取关节振动信息。首先,将关节电流信息引入,建立基于关节电流的工业机器人振动模型。然后,由有限元法进行模态分析获取机器人前6阶振型,便于后续模态试验优化测点布置。接着,在力锤激励试验中,基于优化后的测点,测取工业机器人系统质量、刚度等模态参数。之后,将驱动力矩与模态参数带入该模型进行龙格库塔数值求解,得到机器人各关节振动响应。最后,在指定关节转角运行的关节单动与联动实测振动数据验证了本文提出算法的正确性。

基于能量控制的机器人关节同步优化控制研究

针对移动机器人在高性能输出和长时间续航等方面的综合工作性能需求,提出一种针对机器人关节的多性能同步优化端口受控哈密顿能量控制方法。首先,建立机器人关节的数学模型和哈密顿能量控制模型,并推导出能方便采用模型代理优化算法的关节靶向能量传输系统模型;其次,搭建能量闭环控制器,与磁场矢量控制结合完成机器人关节的控制闭环,并设计了多性能同步优化控制策略使得机器人关节在保证运行输出能力的同时获得最长的续航能力。MATLAB/Simulink仿真结果表明,多性能同步优化端口受控哈密顿能量控制器使机器人关节拥有较好的输出稳定性,同步优化控制策略在与其他控制策略的输出能力和续航能力等多指标的综合对比分析中展现了优势。

结合深度强化学习与变形五次多项式的搬运机器人关节轨迹规划

针对在生产节拍固定的情况下搬运机器人各关节的运动轨迹及时间分配问题,构建基于深度强化学习与变形五次多项式相结合的搬运机器人关节轨迹时间分配模型;设计以节拍要求、速度约束和加速度约束为目标的奖励函数,搭建神经网络,利用MATLAB/Simulink软件,得到满足生产节拍和运动学约束的时间序列,并利用单臂四自由度搬运机器人仿真实验,验证所构建模型的可行性和有效性。结果表明:单臂四自由度搬运机器人各关节的运行时间均为5.89 s,其中平移关节1、 3的最大速度分别为2 597.84、 1 697.97 mm/s,最大加速度分别为19 532.11、 31 302.61 mm/s^(2);旋转关节2、 4的速度大小相等且方向相反,最大角速度均为137.53 (°)/s,最大角加速度均为1 180.51 (°)/s^(2),均未超过运动学约束;所构建的模型可以解决在指定生产节拍下搬运机器人关节轨迹时间分配问题,实现搬运机器人搬运过程中各关节的运动均衡,改善搬运机器人运行的稳定性和有效性。

基于具身智能的移动操作机器人系统发展研究

具身智能是新一轮科技革命与产业变革中的战略性技术,是当前世界各国重点竞争的前沿高地之一;移动操作机器人系统因其优秀的运动、规划、执行能力成为具身技术首选的硬件载体;基于具身智能的移动操作机器人系统作为实现跨领域、多场景、多功能的自主具身智能平台,将成为引领未来新一代信息技术和人工智能发展的关键。本文从基于具身智能的移动操作机器人系统发展的需求出发,总结了基于具身智能的移动操作机器人系统的发展现状,分析了该领域发展面临的问题和挑战,提出了涵盖多模态感知技术、世界认知与理解技术、智能自主决策技术、运动与操作联合规划技术等基于具身智能的移动操作机器人系统的共性关键技术。基于此,本文从国家政策倾斜、共性技术突破、交叉学科建设与人才培养、综合验证平台构建等方面提出了对策建议,以期助力具身智能发展浪潮下我国移动操作机器人领域的长足发展。

机器人辅助全膝关节置换技术的应用与前景

背景:目前用于全膝关节置换的机器人系统设计的基本原理是将三维手术规划、术中危险区预警、实时数据反馈及机械臂辅助截骨等技术相结合,以实现全膝关节置换的精准化、个性化,这也恰好是它最大优势所在,因此近年来成为关节外科领域热点话题,备受关注。目的:文章将从机器人辅助全膝关节置换在关节外科领域的发展现状及其与传统全膝关节置换优劣势对比进行概述,此外,还将对机器人辅助全膝关节置换技术未来的发展进行展望。方法:应用计算机检索PubMed、中国知网、万方和维普数据库的相关文章,英文检索词:“robot OR robotic OR robotics OR robotically OR computer,total knee arthroplasty OR total knee replacement,TKA OR TKR”,中文检索词:“机器人辅助,计算机导航,全膝关节置换术”,最终纳入64篇文献进行综述分析。结果与结论:①用于辅助全膝关节置换的机器人系统根据其自由度分为主动式、半主动式和被动式。半主动式系统是目前使用最为广泛的机器人系统,该系统有效提高了全膝关节置换手术的精准性和个性化程度,但其高昂的使用成本与较长的学习曲线仍是在该领域内推广时需要权衡的主要因素。②机器人辅助全膝关节置换可实现膝关节局部三维空间的精准截骨、正确安置假体,已被广泛证明可以提供更好的假体植入精准度,减少影像学异常值,在术中可获得良好的软组织平衡,最终改善术后膝关节运动及功能状态。③但目前的机器人辅助系统依然存在客观的不足之处,包括不同机器人设备与术者之间的学习曲线问题、额外增加的安装和维护成本以及与机器人手术相关的潜在并发症,所以其能否让医疗系统及患者真正受益仍需要更长期的研究予以证明,机器人辅助系统也仍需进行更多实质性的改进。④机器人辅助全膝关节置换技术在临床上仍然处于初步研究阶段,并没有大范围地应用到临床,更加明确该技术的用法、完善该技术的临床操作规范和安全性成为了未来对该技术的研究侧重点。

移动平台与机械臂联合作业运动规划研究

为解决复合式自动引导车(Automated Guided Vehicle,AGV)在实际作业中需移动平台到达目标点后机械臂再进行运动的工作模式导致的作业耗时长、效率低的问题,提出复合式AGV移动平台与机械臂的联合作业规划。利用栅格法构建环境地图,采用A*算法和蚁群算法分别对移动平台和机械臂进行运动规划,实现了复合式AGV的移动平台和机械臂的联合作业规划。经实验结果验证,联合作业规划比非联合作业平均节省时间为3.75 s,效率平均提高6.27%。

复杂场景下集成协作式木结构智能建造技术

为提高木结构建造技术数字化水平,将已有工艺与机械臂运动系统相结合,形成数字化建造工具系统。以切割、开榫、铣削及开孔四种工艺为例,对木结构数字建造技术进行剖析与设计,辅以建造装备系统、控制系统形成高度集成化的加工系统,借助可视化编程技术手段对工具系统运动轨迹、几何数据分析、自动适配工具及路径自动规划进行标准程序开发,选取斗拱结构进行建造实践。结果表明:所提出的加工系统可精确、高效完成非标准化、定制化异形结构建造任务,开发的标准程序实现了建构逻辑集成化应用,输入构件模型可自动生成机械臂可识别路径,通过实际建造验证了加工系统和标准程序的可行性及适用性。