Development and Calibration of a Hyperstatic Six-component Force/Torque Sensor

The six-component force/torque sensor has become one kind of the most important sensors with the ability of measuring all the external forces and torques. A novel hyperstatic six-component force/torque sensor based on the Stewart platform structure, which can be used for the force measurement of the robot wrist, is proposed, and its structural optimal design, finite element analysis and calibration experimentation is presented. The characteristic of the sensor structure is analyzed in comparison with the traditional Stewart platform-based sensor. The mathematical expression of the sensor＇s force mapping matrix is introduced. The condition number and generalized amplifying coefficient defined by singular values of force Jacobian matrix are used to evaluate the performances of isotropy and sensitivity of the sensor respectively. The optimal design of the sensor structure is performed with the objective of achieving high measurement sensitivity and good isotropy. The sensor prototype is fabricated, and the static and dynamic characteristics of the sensor are analyzed with finite element analysis software package ANSYS. The calibration device is manufactured, and the data acquisition and processing system is developed. The theoretical and experimental study of the static calibration of the sensor prototype is carried out. The results of simulation analysis and calibration experimentation prove the feasibility of the hyperstatic sensor structure, and the contents of this paper possess theoretical significance and engineering value for the further research and practical application of the six-component force sensor.

Miniature 6-axis force/torque sensor for force feedback in robot-assisted minimally invasive surgery

In order to restore force sensation to robot-assisted minimally invasive surgery(RMIS),design and performance evaluation of a miniature 6-axis force/torque sensor for force feedback is presented.Based on the resistive sensing method,a flexural-hinged Stewart platform is designed as the flexible structure,and a straightforward optimization method considering the force and sensitivity isotropy of the sensor is proposed to determine geometric parameters which are best suited for the given external loads.The accuracy of this method is preliminarily discussed by finite element methods(FEMs).The sensor prototype is fabricated with the development of the electronic system.Calibration and dynamic loading tests for this sensor prototype are carried out.The working ranges of this sensor prototype are 30 N and 300 N·mm,and resolutions are 0.08 N in radial directions,0.25 N in axial direction,and 2.4 N·mm in rotational directions.It also exhibits a good capability for a typical dynamic force sensing at a frequency close to the normal heart rate of an adult.The sensor is compatible with surgical instruments for force feedback in RMIS.

Torque Sharing Function Control of Switched Reluctance Machines with Reduced Current Sensors

This paper presents a Torque Sharing Function(TSF)control of Switched Reluctance Machines(SRMs)with different current sensor placements to reconstruct the phase currents.TSF requires precise phase current information to ensure accurate torque control.Two proposed methods with different chopping transistors or a new PWM implementation require four or two current sensors to replace the current sensors on each phase regardless of the phase number.For both approaches,the actual phase current can be easily extracted during the single phase conducting region.However,how to separate the incoming and outgoing phase current values during the commutation region is the difficult issue to deal with.In order to derive these two adjacent currents,the explanations and comparisons of two proposed methods are described.Their effectiveness is verified by experimental results on a four-phase 8/6 SRM.Finally,the approach with a new PWM implementation is selected,which requires only two current sensors for reducing the number of sensors.The control system can be more compact and cheaper.

Design and calibration of spoke piezoelectric six-dimensional force/torque sensor for space manipulator

The large manipulator outside the space cabin is a multi-degree of freedom actuator for space operations.In order to realize the automatic control and flexible operation of the space manipulator,a novel spoke structure piezoelectric six-dimensional force/torque sensor with redundancy ability,high stiffness and good decoupling performance is innovatively proposed.Based on the deformation coordination relationship,the redundancy measurement mechanism is revealed.The mathematical models of the sensor with and without branch fault are established respectively.The finite element model is established to verify the feasibility of structure and redundancy measuring principle of the sensor.Depending on the theoretical analysis and simulation analysis,the prototype of the sensor is developed.Static and dynamic calibration experiments are carried out.The actual output voltage signal of the six-dimensional force/torque sensor is collected to establish the equation between the standard input applied load and the actual output voltage signal.Based on ant colony optimized BP algorithm,performance indexes of the sensor with and without branch fault are analyzed respectively.The experimental results show that the spoke piezoelectric sixdimensional force/torque sensor with the eight-point support structure has good accuracy and reliability.Meanwhile,it has strong decoupling characteristic that can effectively shield the coupling between dimensions.The nonlinear errors and maximum interference errors of decoupled data with and without branch faults are less than 1% and 2%,respectively.The natural frequency of the sixdimensional force sensor can reach 2856.45 Hz and has good dynamic characteristics.The research content lays a theoretical and experimental foundation for the design,development and application of the new six-dimensional force/torque sensors with redundancy.Meanwhile,it will significantly improve the research level in this field,and provide a strong guarantee for the smooth implementation of force feedback control of the space station manipulator project.

基于Modbus/TCP的电容式扭矩传感器数据采集系统设计

扭矩传感器通常安装于机械设备的旋转关节处,用于扭矩的测量。电容式扭矩传感器需要配备专门的数据采集系统才能使用,且数据采集系统的性能直接影响传感器的精确测量。针对实验室自主研制的电容式扭矩传感器的应用需求,设计了一种基于Modbus/TCP协议的数据采集系统。系统以STM32为主控芯片,通过控制电容数字转换芯片AD7147实现电容信号采集与转换,然后由W5500以太网芯片将数据上传到自主开发的上位机软件中进行处理、显示与存储。实验测试表明:系统最大测量误差为1.47%,数据输出频率为1000 Hz。

谐波减速器集成式扭矩传感器的设计与测试

为实现协作机器人关节力控和提高集成度,提出一种集成于谐波减速器内部的扭矩传感器,以精确获取关节输出扭矩值,推动智能化控制的实现。采用有限元计算方法分析了谐波减速器柔轮底面应变与加载扭矩之间的规律;然后根据有限元分析的结果,考虑柔轮底面敏感栅在不同栅丝长度、栅丝间距和栅丝位置情况下,建立底面应变与扭矩变化皮尔逊相关系数的响应面模型,求解模型获得最优的敏感栅结构参数,确保该结构下集成式传感器具有最佳线性响应,结合惠斯通电桥原理设计扭矩传感器结构;最后,对集成式扭矩传感器进行标定和测试。结果表明:集成式扭矩传感器的灵敏度为0.249 mV/N·m,线性度为0.99974,迟滞误差为2.19%。施加0~70 N·m之间阶梯变化的负载扭矩并进行重复实验,集成式扭矩传感器相对于标准扭矩传感器均方根误差为0.89~0.98 N·m。施加在±70 N·m之间正弦变化的负载扭矩,均方根误差为0.96~1.05 N·m。该集成式扭矩传感器能够较为精准地感应负载扭矩,有助于实现协作机器人关节力控制,提升机器人系统的集成度。

磁聚焦式扭矩传感器激励线圈控制策略研究

为测量旋转轴不同工况下的扭矩,提出了一种基于磁聚焦式扭矩传感器的激励线圈控制策略。该控制策略以控制传感器稳定输出幅值为2 mV电信号为目标,将感应电压数学模型和正交试验法相结合,对各个工况下的激励线圈控制策略进行设计,并利用MATLAB和COMSOL软件对各控制策略进行理论计算和有限元仿真验证。为模拟传感器在台架实验中得到的带噪声信号,对仿真得到的输出电信号添加高斯白噪声,利用MATLAB仿真软件对带噪声信号进行滤波优化。仿真结果表明:该控制策略能够使传感器在旋转轴的不同工况下,稳定输出幅值为2 mV的类正弦电压信号,验证了其可行性。

考虑电磁干扰的差动式电容力矩传感器动态校准方法

在差动式电容力矩传感器校准过程中,受设备电磁干扰的影响,造成校准结果存在较大偏差。为解决这一问题,在考虑电磁干扰的前提下,提出差动式电容力矩传感器动态校准方法。在差动式电容力矩传感器存在电磁干扰的情况下,采用小波变换方法抑制传感器中的电磁干扰。通过差动式电容力矩传感器的组成结构构建参数化数学模型,获取动态激励和结构响应两者之间的频域传递关系,利用最小二乘法分析传递函数的频域几何关系式,对传感器展开动态解耦和动态补偿。通过冲击剪断装置形成的力矩信号对传感器动态标定,利用检测电路测量阶跃信号对标定结果校准,完成差动式电容力矩传感器动态校准。实验测试结果表明,所提方法可以获取满意的动态校准结果。

基于EKF的PMSM无位置传感器控制

为了获得永磁同步电机转子的位置信息,提出了一种五阶扩展卡尔曼滤波器(EKF)的算法;在传统的四阶EKF中引入对负载转矩的估算,并将其前馈至电流环以解决速度环对外界负载扰动响应慢的问题;通过设计改进的递推最小二乘法实时辨识电机的转动惯量,优化了系统的观测性能和鲁棒性,基于Simulink搭建仿真模型,结果表明该观测器性能优秀且提高了系统的抗扰动性能;最后,通过硬件实验实现了电机位置误差仅在0.02 rad以内,且负载转矩观测误差在4%以内,有效改善了系统在有负载波动时的动态特性。

双偏心动态扭矩-转速传感器弹性体仿真与优化

动态扭矩的检测对于旋转动力设备的运行起到很重要的作用,通过实时检测设备工作时的扭矩,可以间接分析出设备的工作状态。设计了一款非接触式的动态扭矩传感器,其可以通过测量偏心距来间接计算出实时扭矩。利用ANSYS软件仿真了不同材料下传感器弹性体的最大切应力,扭转角度和1阶固有频率,选出扭转角度和屈服极限较大的17-4PH材料。采用中心复合实验和拉丁超立方实验的方法对传感器开槽前后生成不同的实验数据表,并对实验数据进行了方差分析。针对扭转角度和1阶固有频率进行多目标响应面优化,优化结果表明:没有开槽的传感器进行优化得到的扭转角度提高了15.7%,开槽后的传感器得到的扭转角度提高了19.4%。

谐波减速器转矩原位测量及误差补偿

为实现协作机器人精准力控,利用谐波减速器柔轮变形研制了一种原位集成转矩传感器。提出了基于傅里叶级数模型的剩余纹波补偿方法提高测量精度。提出了基于傅里叶级数模型的剩余纹波补偿方法提高测量精度。首先,分析了柔轮底部应变规律,通过正弦叠加的原理设计了应变敏感栅结构;然后建立纹波与波发生器角度之间的傅里叶级数模型,补偿剩余纹波;最后,研制了测试平台进行加载测试,结果表明,在波发生器静止状态下施加瞬时激励和阶跃负载,自制转矩传感器与标准转矩传感器输出误差为0.988%和0.253%;在波发生器旋转状态下施加阶梯变化、正弦变化、正弦变化过程中人为碰撞三种形式的负载,自制转矩传感器与标准转矩传感器输出误差为3.822%,4.247%和4.456%。本文提出的补偿方法能有效降低剩余纹波对传感器输出的干扰,有利于推动关节转矩精准测量的实现。

基于FPGA的光纤式旋转扭矩测量系统设计

针对在挠性连接的大型传动设备的运行状态健康监测中有效提高旋转状态下中高扭矩测量准确性的问题,设计了一套可用于挠性连接的基于FPGA的光纤式旋转扭矩测量系统。采用带有30组明暗相间膜片的转盘,利用光纤传感器将轴的扭转信号转换为光电信号输出,采用施密特整形电路将传感器输出的模拟信号转换为数字信号连入FPGA中。通过FPGA内部的可编程逻辑单元与高频计数器,将数字信号转换为计数值的形式,并发送至上位机。通过LabVIEW编写上位机软件,实现数据整周期处理的功能,并将结果显示出来。在刚性连接的实验中,系统对旋转稳态扭矩测量的相对误差均优于2.0%;在挠性连接的实验中,系统对旋转稳态扭矩测量的相对误差均优于3.0%。证明该系统在500~2 000 N·m范围的不同连接方式下,对旋转稳态下扭矩的测量都具有较好的准确性。

基于参数辨识的磁聚焦式扭矩传感器模型研究

为解决磁聚焦式扭矩传感器模型未知参数问题,实现其更精确地测量,文中通过对此传感器机理分析建立了数学模型与非零初始条件下的系统模型,确定了辨识参数矩阵。提出了一种预测误差法与自适应粒子群算法相结合的参数辨识方法。搭建正弦激励校准实验系统对其进行验证,结果表明,该方法有效地实现了传感器参数的辨识,得到的传感器模型具有较高的精度,为其动态特性分析与误差补偿提供了可靠依据。

基于转矩振幅动态信号去噪的航空发动机转矩振动模糊控制技术

航空发动机转矩振动会引起机身共振,导致机身振动增大,引发结构失效;为了确保飞机的安全性,设计基于转矩振幅动态信号去噪的航空发动机转矩振动模糊控制技术;基于航空发动机整机动力学分析结果,明确其运行过程中的幅值、频率、相位等振动特性;以此为基础,使用MEMS加速度传感器采集航空发动机实际转矩振幅动态信号,并利用奇异谱分析算法对采集到的动态信号实施去噪处理,提取出主要的信号成分;设计模糊控制技术,并将去噪处理后的转矩振幅动态信号作为输入变量,实现发动机转矩振动模糊控制;测试结果表明,设计控制技术应用后,具备适应不同转子位移变化的能力;在不同支承刚度下,设计控制技术的转矩振动抑制率较高;在宽频状态测试点处外机匣表面加速度收敛至0.04 m/s 2以内,窄频状态测试点处外机匣表面加速度收敛至0.03 m/s 2左右;因此,设计控制技术具有良好的控制效果,可以保证航空发动机的稳定性和具有较高的抑制性能。

汽车装配生产线电动伺服螺纹拧紧设备发展现状

中国汽车销量已经连续14年居世界第一,螺纹连接为汽车零部件之间的主要连接形式,螺纹拧紧设备市场需求巨大。目前国内汽车生产线上的拧紧设备主要依靠进口,造价高,已经成为卡脖子问题。为此文章针对汽车生产线的电动伺服螺纹拧紧设备的关键技术展开论述:对比了交流永磁伺服同步电机的控制策略;论述了拧紧设备的减速机构方案;对比了不同的扭矩检测方案;最后分析了国内外现有的电动伺服螺纹拧紧设备的特点。通过对电动伺服螺纹拧紧设备关键技术的研究分析,指出了现阶段电动伺服拧紧设备上不同技术方案的优缺点及发展趋势,为国内电动伺服螺纹拧紧设备的研究与开发提供了思路。

5 kN·m变温环境下扭矩校准装置试验分析

文章介绍了5 kN·m变温环境下扭矩校准装置结构与工作原理,通过整机试验定量分析了装置的测量不确定度,并进行了标准扭矩传感器的校准试验。结果表明:设计的装置能够为变温环境下的扭矩传感器溯源提供理论和溯源依据。

Preliminary Design of Pressure Torque Separation Sensor for Drilling Bit

The working state of drilling bit is a critical issue in the drilling process. The preliminary design of pressure and torque separation sensor for drilling bit is expatiated herein. The sensor unit is composed of the elastic unit and the Wheatstone full bridge. Under composited load, the theoretical analysis about separating the axial force and torque of drilling bit is discussed firstly. The separation has been achieved by using the Wheatstone full bridge pasted onto the elastic unit. Then the transversal and axial strains distribution of elastic unit has been calculated and analyzed by ANSYS software, when the bit is under axial force and torque. Based on the calculation and analysis results, the sensitivity and accuracy of the sensor's whole measurement chain can be reckoned. Meanwhile, the calculation and analysis results can also give good suggestion about the positions where the strains gauge should be pasted. Finally, it has been proved that this solution can meet the preset requirements very well.

用于高精度电动钻孔器的复合力传感器设计

设计了一种用于高精度电动钻孔器的复合力传感器,能够为电动钻孔器的转速及进给速度的自动调节提供准确有效的反馈判断参数。传感器安装在电动钻孔器的驱动轴和钻头之间,能够将钻头受到的扭矩和沿轴线方向的阻力实时反馈给控制机构。传感器的旋转轴和弹性体采用一体式结构,通过力学计算确定了其应变与扭矩和轴向阻力成近似线性关系;利用有限元方法分析了弹性体的应变分布、扭力和阻力之间的相互影响和极限形变;通过实验,得到了传感器的解耦矩阵。实践表明,传感器扭矩信号的灵敏度可达2.6 mV·V^(-1),综合测量误差≤0.5%,阻力信号的灵敏度可达2.2 mV·V^(-1),综合测量误差≤2%。传感器安装在电动钻孔器上,能够将扭矩信息和阻力信息实时反馈给控制机构,有助于电动钻孔器及时和准确地对转速和进给速度进行主动调节。

油井套管扭矩测量方法研究

在石油钻井与勘探领域,油井套管主要采用螺纹连接方式,其性能直接关系到油井套管连接的紧密性与密封性,因而应用扭矩仪测量并设定适宜扭矩值以确保套管螺纹紧固至关重要。应变片式扭矩仪作为主流的扭矩传感器,在套管作业中发挥着重要作用。通过分析扭矩作用下弹性轴的应力状态,结合应变片的形变响应,实现扭矩与应变片电阻变化量之间的量化关系转换,即为力学量向电学信号的转化。利用惠斯通全桥电路构建线性关系模型,直接反映电桥输出电压与扭矩的对应关系,从而精确测定扭矩值。该技术具有检测误差小和性能稳定的特点,对优化油井套管作业中的扭矩控制具有重要意义。

一种基于TMR技术的力矩传感器设计

针对电助力自行车的动态力矩测量,设计一种基于穿隧磁阻(Tunneling Magneto Resistive,TMR)的一维力/力矩的检测系统以及一种无线数能同传系统,用于测量人体在骑行过程中,施加在中轴上的力矩,并实现力矩传感器信号的多级放大以及信号采集软件和硬件的设计。应用控制器局域网络(Controller Area Network,CAN)总线接口与外部上层控制器通信,实时计算和传递电助力自行车骑行过程中的力矩信号。实验结果证明,该传感系统能够完成脚底踩踏力矩信息的实时采集、计算与通信。