点焊机器人轨迹能耗模型及其优化算法研究

提出一种点焊机器人最优能耗轨迹优化方法,将机器人关节空间中的关键点用五次多项式曲线连接,并基于机器人动力学建立了永磁交流伺服电机驱动的点焊机器人轨迹能耗模型。在考虑运动学、动力学及生产周期约束的情况下,采用蜜蜂进化型遗传算法求解了点焊机器人最优能耗轨迹。为保证算法全局寻优和收敛速度,构建了一种非线性适应度函数。仿真结果表明,与之前算法相比,求解效率更高,且最优能耗轨迹较最短时间轨迹能耗明显减少。     

一种协作机器人位姿重复性优化综合

在给定位姿重复性要求的前提下,寻找各关节随机运动精度的最优分配方案能够使协作机器人设计更加合理,对降低机器人制造成本有重要意义.首先,在机器人位姿重复性分析的基础上,建立了位姿重复性数学模型,该数学模型包含机器人位置重复性和姿态重复性;其次,以协作机器人KUKA iiwa 7为例,以关节运动误差最大化为优化目标,对该机...     

基于双目立体视觉的工业机器人在线温度补偿

工业机器人在工业现场进行连续高速作业过程中,电机发热和关节摩擦生热将导致机械臂本体温度升高,引起机器人末端定位漂移,严重影响机器人的重复定位精度和作业精度。针对制造现场的工业机器人,提出了一种基于双目立体视觉的温度误差在线补偿方法,并基于微分运动学和双目视觉原理构建了温度误差补偿模型。在机器人末端安装基准球,同时在基座附近固定视觉测量传感器,机器人完成作业循环之后,以不同的姿态带动基准球至传感器视场内进行补偿测量。此外,通过分析各关节参数随时间变化的规律,筛选出符合温度漂移规律的显著性参数进行补偿,有效降低了补偿测量次数和耗时。实验结果显示,补偿后机器人的重复定位精度可维持在±0.1mm的水平,能够显著改善制造现场工业机器人的作业精度,且整个补偿测量过程耗时10s左右。     

新型内窥镜机器人结构优化设计研究

研究了一种结构简单的新型内窥镜机器人驱动机构,并建立了内窥镜机器人在人体内腔中运动的数学模型.采用有限差分法分析了内窥镜机器人结构特性参数对机器人的最小粘液膜厚度和轴向摩擦牵引力的影响,从而获得当需要较厚的粘液膜厚度和较大的轴向摩擦驱动力时最优的机器人结构特性参数,为机器人更好地以较厚的粘液膜厚度和较快的速度悬浮式运行创造条件.内窥镜机器人的运行速度试验证明了此理论分析模型的正确性.     

Tolerance design of robot parameters using Taguchi method

A robotic arm must be able to manipulate objects with high accuracy and repeatability. As with every physical system, there are number of noise factors cause uncertainty in the performance. A probabilistic approach has been used to model, the otherwise difficult to model, noise effects. This paper presents the approach utilised in selection of tolerance specification of robot kinematic and dynamic parameters using experimental design technique for reduction of performance variations. The concept of inner and outer orthogonal arrays proposed by Taguchi is employed to identify the significant parameters and select the optimal tolerance range. The performance measure, i.e. signal-to-noise ratio is utilised to validate by Monte Carlo simulations and to complement above study individual parameter tolerance sensitivity are investigated. To provide insight to investigation, parameter sensitivity maps are plotted. The tolerance specification selection methodology of a manipulator is illustrated by taking 2-DOF RR planar manipulator with payload.     

基于模具表面抛光机器人系统的运动控制研究

介绍了自行研制的模具表面抛光机器人系统的构成和工作原理,建立了面向自由曲面抛光精加工的机器人模型,应用新的算法,快速且准确地求出运动学逆解。在不限制机器人运动范围的基础上,运用数值比较法解决机器人关节变量多解所导致的关节值突变问题。通过实验证实了该算法的正确性和有效性,为系统控制速度能力的提高和运动轨迹的优化提供了理论依据。     

一种具有跳跃能力的自平衡两轮机器人动力学建模与越障控制

针对传统机器人越障能力不足的问题,结合本实验室设计的一种具有跳跃能力的自平衡两轮机器人,建立了机器人的动力学模型.分析了两轮机器人最大可控角的影响因素,建立了弹跳准备阶段的模糊滑模控制器,实现对机器人摆角与移动速度的控制.对机器人在起跳阶段做了动力学分析,对机器人在腾空阶段的运动做了动力学分析,同时根据障碍物外形,对其越障运动做了轨迹规划.最后,通过仿真与实验研究,验证了所建立的跳跃越障控制方法的有效性.     

Robot calibration using an automatic theodolite

The Vision Based Automatic Theodolite (VBAT) is an automatic partial pose measurement system for robot calibration. It uses low resolution rotation stages and resolution enhancement from a vision system to determine the line-of-sight to a spherical illuminated target. Automatic tracking, focusing, and centring provide the calibration system with speed, reliability, and repeatability. A kinematic model of the VBAT is described which includes both the mechanical parts of the system and the optics, using a modified Denavit-Hartenberg approach. All parameters in the VBAT model are identified and embedded into the system controller producing an instrument of 2 arc second accuracy. The system is then used in a conventional manner to calibrate a six degree of freedom PUMA robot, and the results compared to another calibration of the same arm by a coordinate measuring machine with repeatability and accuracy of 0.02 mm. The calibration using the VBAT enhances the accuracy of the PUMA to within 0.2 mm of that produced by the CMM calibration, compared to an accuracy of 14 mm prior to calibration.     

MATHEMATICAL MODEL OF REPEATABILITY FOR ROBOTS

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A non-contact method for detecting on-line industrial robot position errors using a microwave doppler radar motion detector

To be useful, industrial robots must meet positioning accuracy requirements for their given applications. Off-line calibration generally improves robot positioning accuracy to levels needed for open-loop use in most industrial applications. Applications that require greater accuracy with respect to external assemblies generally turn to closed-loop control or passive compliance. However, industrial robot systems do not generally monitor in-process robot position to detect machine faults that can lead to product faults, scrap, machine damage, and additional costs. To achieve greater operational efficiencies, new non-invasive, noncontact methods for monitoring robot position are needed. The investigators developed a low-cost method for in-process industrial robot position monitoring using a Doppler motion detector and a statistical position error measure. The method detects position errors at robot repeatability levels.     

A non-contact method for detecting on-line industrial robot position errors using a microwave Doppler radar motion detector

To be useful, industrial robots must meet positioning accuracy requirements for their given applications. Off-line calibration generally improves robot positioning accuracy to levels needed for open-loop use in most industrial applications. Applications that require greater accuracy with respect to external assemblies generally turn to closed-loop control or passive compliance. However, industrial robot systems do not generally monitor in-process robot position to detect machine faults that can lead to product faults, scrap, machine damage, and additional costs. To achieve greater operational efficiencies, new non-invasive, non-contact methods for monitoring robot position are needed. The investigators developed a low-cost method for in-process industrial robot position monitoring using a Doppler motion detector and a statistical position error measure. The method detects position errors at robot repeatability levels.     

六自由度工业机器人手腕分析与优化综合

本文分析了用于六自由度工业机器人的球型手腕, 这种手腕具有结构紧凑, 姿态范围大, 定位精度高等特点.在运动学分析的基础上, 研究了手腕定位精度与各关节参数精度误差之间的关系, 给出了完整的误差数学模型, 借助于此模型通过优化设计, 得到了各关节参数精度的合理分配, 为机器人机械结构及控制系统的精度设计提供了依据.文章阐述了使机器人实现快速响应, 提高定位精度的优化设计方法.     

一种多功能下肢外骨骼机器人的设计与仿真分析

针对老年人以及下肢运动障碍患者的康复训练和运动代步的需求,设计了一种多功能下肢外骨骼机器人,利用辅助起立机构和腿部外骨骼实现对使用者下肢的康复训练。分别了建立外骨骼机器人单腿支撑阶段和双腿支撑阶段5杆模型,采用拉格朗日方法推导出动力学模型,计算各关节所需的理论力矩;建立虚拟样机模型进行动力学仿真,仿真数据与理论数据进行比较,验证了理论推导的准确性和外骨骼机器人设计的合理性,为后续电机选型提供了依据。     

基于最优位姿集的机器人标定及不确定度评定

为解决因标定位姿点随机选择导致机器人标定结果不稳定、可靠性低问题,研究了基于雅克比矩阵奇异值计算可观测指标的最优位姿点数目及最优位姿集选择算法,建立了机器人MDH模型,采用LM算法对几何参数进行辨识,使用LeicaAT960激光跟踪仪分别在最优位姿集和随机位姿集下对Staubli TX60机器人末端位姿大量实测;在分析研究机器人标定不确定度来源基础上,采用测量不确定指南(GUM)计算几何参数标定的不确定度及蒙特卡洛模拟法对机器人末端位置不确定度进行评估,结果表明,经最优位姿集标定后的机器人不仅在测试点精度有大幅提升,而且几何参数及末端位置平均不确定度约为随机位姿集标定的0.11倍,标定结果稳定可靠,泛化能力强,适于在高精度、大范围作业场合推广应用。     

Energy Expenditure of Trotting Gait Under Different Gait Parameters

Robots driven by batteries are clean, quiet, and can work indoors or in space. However, the battery endurance is a great problem. A new gait parameter design energy saving strategy to extend the working hours of the quadruped robot is proposed. A dynamic model of the robot is established to estimate and analyze the energy expenditures during trotting. Given a trotting speed, optimal stride frequency and stride length can minimize the energy expenditure. However, the relationship between the speed and the optimal gait parameters is nonlinear, which is difficult for practical application. Therefore, a simplified gait parameter design method for energy saving is proposed. A critical trotting speed of the quadruped robot is found and can be used to decide the gait parameters. When the robot is travelling lower than this speed, it is better to keep a constant stride length and change the cycle period. When the robot is travelling higher than this speed, it is better to keep a constant cycle period and change the stride length. Simulations and experiments on the quadruped robot show that by using the proposed gait parameter design approach, the energy expenditure can be reduced by about 54% compared with the 100 mm stride length under 500 mm/s speed. In general, an energy expenditure model based on the gait parameter of the quadruped robot is built and the trotting gait parameters design approach for energy saving is proposed.     

Development and Polishing Process of a Mobile Robot Finishing Large Mold Surface

□ A novel self-determination polishing robot finishing large mold free-form surface is developed, and the finishing process method is researched. Contrary to traditional approaches, our premise is that a large mold surface can be polished by using a small robot. This robot system is mainly composed of a polishing robot part, a computer system and a visual positioning system. A type of robot with four uniform distribution wheels was designed, which has two driving wheels and two driven wheels. Active compliant control of the polishing tool was provided by a pneumatic servo system, and a new special compliant abrasive tool was proposed on the basis of robot characteristics. The process planning steps consisted of subdividing the free-form surface, choosing an abrasive tool, planning the polishing path and optimizing machining parameters. Based on the orthogonal experiment and the grey relational analysis method, the optimal parameter combination was obtained for polishing force, tool speed and feed rate. Aiming to polishing times, the surface roughness method and polishing efficiency method were studied in detail. The polishing experiments were carried out in the robot using process parameters obtained by the efficiency method. These research results provided significant theory foundation and experimental data for a mobile robot planning polishing to realize intelligible process parameter selection.     

Attribute based specification, comparison and selection of a robot

The problem of robot selection has been of concern to manufacturers for many years. This problem has become more difficult in recent years due to increasing complexity, available features, and facilities offered by different robotic products. The objective of this research is to generate and maintain reliable and exhaustive database of robot manipulators based on their different pertinent attributes. This database can be used to standardize the robot selection procedure when the manufacturing firm has decided to use the robot for a particular operation. This will help the robot user to save time by providing him a tool for selecting the robot system most suited for his operational needs. The robot selection procedure allows rapid convergence from a very large number of candidate robots to a manageable shortlist of potentially suitable robots using ‘elimination search’ based on the few critical selection attributes. Subsequently, the selection procedure proceeds to rank the alternatives in the shortlist by employing different attributes based specification methods and graphical methods. The ranks of the candidate robots are calculated with respect to the best possible robot, say +ve benchmark robot, for particular application. This ranking will provide a good guidance for the robot user to select the robot. It will also provide a good insight to the robot manufacturer so that he can improve his product or introduce new product to fulfill the need of customer. It will help the designer at various design stages, while the maintenance people can plan maintenance strategy to reduce the down time and maintenance efforts. This is an attempt to create exhaustive database by identifying maximum possible number of attributes for robot manipulators. The coding scheme and the selection procedures, mathematical and graphical, are illustrated with example.     

码垛机器人结构设计与运动分析

根据目前物流自动化对箱包等物料高速码垛的工作要求,确定了码垛机器人的基本技术指标,设计了四自由度关节型码垛机器人的机械结构。通过运动学分析得出了码垛机器人的运动学方程,并通过对运动学方程的逆解求出码垛机器人各关节的位姿,应用SolidWorks软件构建了码垛机器人的三维实体模型,进行模型装配,实现了码垛机器人码垛过程的仿真。对码垛机器人结构的设计与运动学分析可以为设计和生产码垛机器人提供借鉴。     

Piezoelectric inertial robot for operating in small pipelines based on stick-slip mechanism: modeling and experiment

Small pipes exist in industrial and biomedical fields, and require microrobots with high operational precision and large load capacity to inspect or perform functional tasks. A piezoelectric inertial pipeline robot using a “stick-slip” mechanism was proposed to address this requirement. In this study, the driving principle of the proposed robot was analyzed, and the strategy of the design scheme was presented. A dynamics model of the stick-slip system was established by combining the dynamics model of the driving foot system and the LuGre friction model, and the simulation analysis of the effect of system parameters on the operating trajectory was performed. An experimental system was established to examine the output characteristics of the proposed robot. Experimental results show that the proposed pipeline robot with inertial stick-slip mechanism has a great load capacity of carrying 4.6 times (70 g) its own mass and high positioning accuracy. The speed of the pipeline robot can reach up to 3.5 mm/s (3 mm/s) in the forward (backward) direction, with a minimum step distance of 4 μm. Its potential application for fine operation in the pipe is exhibited by a demonstration of contactless transport.     

Vision-based stabilization of nonholonomic mobile robots by integrating sliding-mode control and adaptive approach

Vision-based pose stabilization of nonholonomic mobile robots has received extensive attention.At present,most of the solutions of the problem do not take the robot dynamics into account in the controller design,so that these controllers are difficult to realize satisfactory control in practical application.Besides,many of the approaches suffer from the initial speed and torque jump which are not practical in the real world.Considering the kinematics and dynamics,a two-stage visual controller for solving the stabilization problem of a mobile robot is presented,applying the integration of adaptive control,sliding-mode control,and neural dynamics.In the first stage,an adaptive kinematic stabilization controller utilized to generate the command of velocity is developed based on Lyapunov theory.In the second stage,adopting the sliding-mode control approach,a dynamic controller with a variable speed function used to reduce the chattering is designed,which is utilized to generate the command of torque to make the actual velocity of the mobile robot asymptotically reach the desired velocity.Furthermore,to handle the speed and torque jump problems,the neural dynamics model is integrated into the above mentioned controllers.The stability of the proposed control system is analyzed by using Lyapunov theory.Finally,the simulation of the control law is implemented in perturbed case,and the results show that the control scheme can solve the stabilization problem effectively.The proposed control law can solve the speed and torque jump problems,overcome external disturbances,and provide a new solution for the vision-based stabilization of the mobile robot.