A novel parallel sensor with six rigid compliant limbs for measuring six- component force/torque

A novel parallel sensor with six rigid/compliant hybrid limbs and six standard force sensors is developed for measuring the six-component force/torque. The measuring theory and performances are studied. A prototype of the robot hybrid hands with the parallel sensor is developed. A prototype of the parallel sensor is built up and its merits and performances are analyzed. A statics equation among the forces of the standard force sensors and the whole external load and a stiffness model of the parallel sensor are established based on its equivalent parallel mechanism. The force/torque of the parallel sensor is measured under the given external load. The theoretical solutions of the statics model of the parallel sensor are obtained and verified by both the experimental measuring solutions of the prototype of the parallel sensor and the simulation solutions of a FE model.

     

Research on the parallel load sharing principle of a novel self-decoupled piezoelectric six-dimensional force sensor

This paper presents a novel integrated piezoelectric six-dimensional force sensor which can realize dynamic measurement of multi-dimensional space load. Firstly, the composition of the sensor, the spatial layout of force-sensitive components, and measurement principle are analyzed and designed. There is no interference of piezoelectric six-dimensional force sensor in theoretical analysis. Based on the principle of actual work and deformation compatibility coherence, this paper deduces the parallel load sharing principle of the piezoelectric six-dimensional force sensor. The main effect factors which affect the load sharing ratio are obtained. The finite element model of the piezoelectric six-dimensional force sensor is established. In order to verify the load sharing principle of the sensor, a load sharing test device of piezoelectric force sensor is designed and fabricated. The load sharing experimental platform is set up. The experimental results are in accordance with the theoretical analysis and simulation results. The experiments show that the multi-dimensional and heavy force measurement can be realized by the parallel arrangement of the load sharing ring and the force sensitive element in the novel integrated piezoelectric six-dimensional force sensor. The ideal load sharing effect of the sensor can be achieved by appropriate size parameters. This paper has an important guide for the design of the force measuring device according to the load sharing mode.     

新型预紧式六维力传感器及其位姿误差分析

为了获得综合性能指标优良的六维力传感器,本文提出一种新型的基于Stewart平台的预紧式六维力传感器结构,并对其进行了位姿误差分析。首先以经典Stewart平台六维力传感器为比较对象,描述了此预紧式六维力传感器的结构特点;而后综合利用影响系数法和矢量法建立其位姿误差模型,进而定义位姿误差灵敏度指标并据此绘制误差灵敏度直方图以分析不同误差因素对传感器位姿误差的影响情况;最后研制出传感器样机并完成标定实验,实验结果表明该传感器测力精度在1%以内。所研究内容对六维力传感器的设计制造和实验标定具有理论指导意义。     

Research on parallel load sharing principle of piezoelectric six-dimensional heavy force/torque sensor

In working process of huge heavy-load manipulators, such as the free forging machine, hydraulic die-forging press, forging manipulator, heavy grasping manipulator, large displacement manipulator, measurement of six-dimensional heavy force/torque and real-time force feedback of the operation interface are basis to realize coordinate operation control and force compliance control. It is also an effective way to raise the control accuracy and achieve highly efficient manufacturing. Facing to solve dynamic measurement problem on six-dimensional time-varying heavy load in extremely manufacturing process, the novel principle of parallel load sharing on six-dimensional heavy force/torque is put forward. The measuring principle of six-dimensional force sensor is analyzed, and the spatial model is built and decoupled. The load sharing ratios are analyzed and calculated in vertical and horizontal directions. The mapping relationship between six-dimensional heavy force/torque value to be measured and output force value is built. The finite element model of parallel piezoelectric six-dimensional heavy force/torque sensor is set up, and its static characteristics are analyzed by ANSYS software. The main parameters, which affect load sharing ratio, are analyzed. The experiments for load sharing with different diameters of parallel axis are designed. The results show that the six-dimensional heavy force/torque sensor has good linearity. Non-linearity errors are less than 1%. The parallel axis makes good effect of load sharing. The larger the diameter is, the better the load sharing effect is. The results of experiments are in accordance with the FEM analysis. The sensor has advantages of large measuring range, good linearity, high inherent frequency, and high rigidity. It can be widely used in extreme environments for real-time accurate measurement of six-dimensional time-varying huge loads on manipulators.     

Dynamic characteristics of piezoelectric six-dimensional heavy force/moment sensor for large-load robotic manipulator

This paper presents research on dynamic characteristics of a piezoelectric six-dimensional heavy force/moment sensor for a large-load robotic manipulator. The theory on dynamic characteristics of the sensor structure is analyzed, and a mathematical model of the sensor dynamics, decoupled into separate vibration modes, is provided. This model is complemented by dynamic mode analysis of the sensor by finite-element modeling (FEM; ANSYS software). A dynamic calibration experiment is designed, and methods and principles for measurements and data analysis are provided. The characteristic dynamic vibration modes of the piezoelectric force/moment sensor are extracted by analyzing experimental data, yielding amplitude frequency and phase frequency curves of the transfer function linking the excitation loads with the output signals of the transducer. The results of the dynamic calibration experiment demonstrate the good dynamic characteristics of the piezoelectric six-dimensional heavy force/moment sensor. The natural frequencies in the three force directions are high, with values close 2000 Hz. This demonstrates the applicability of the presented six-dimensional heavy force/moment sensor to large industrial robotic manipulators.     

新型3—2—1正交结构机器人六分量腕力传感器设计

基于变异形式的Steewart平台机构,设计了一种新颖的3－2－1正交结构的机器人六分量腕力传感器,应用并联机器人机构学理论,推导出力六分量表达式并对其刚度特性进行分析,为其设计和使用提供理论依据,这种六分量腕力传感器,具有力与力矩解耦和解算简单等优点。     

旋转惯性压电电机最优驱动方案分析

提出了一种新型旋转惯性压电电机,推导了旋转惯性压电电机在非对称信号激励下的惯性冲击力矩方程以及电机平均输出力矩方程;分析了系统参数对激励信号突变时刻惯性冲击力之差的影响规律;给出了旋转惯性压电电机可输出速度与转矩的最优驱动频率区间。最后通过实验系统验证了理论计算与分析的正确性。     

A novel piezoelectric 6-component heavy force/moment sensor for huge heavy-load manipulator's gripper

This paper presents the development of a piezoelectric 6-component heavy force/moment sensor which may be used to detect forces F_x, F_y and F_z, and moments M_x, M_y and M_z on huge heavy-load manipulator's gripper, simultaneously. The structure of the sensor is newly modeled. Piezoelectric quartz is chosen as force sensing element to realize real-time measurement. In order to investigate the validity of the proposed method, a prototype of piezoelectric 6-component heavy force/moment sensor is developed, and a characteristic test of the piezoelectric 6-component heavy force/moment sensor is performed. The experiments show that the linearity of the sensor is no more than 1%, and the interference errors are less than 3%. The carrying capability of force sensor is improved greatly by using load distribution.     

超静定并联式六维力传感器动力学

提出了一种新型的基于Stewart平台的超静定并联式六维力传感器结构,并对其进行了动力学理论分析和有限元仿真研究.描述了该传感器相对于经典Stewart平台六维力传感器所具有的结构特点;利用有限元法,采用位移协调和力平衡条件建立了传感器弹性动力学理论模型,依此模型进行数值分析,绘制了固有频率与各结构参数间变化关系曲线;并利用ANSYS软件建立了传感器有限元模型,进行了振动模态分析,得到其固有频率和振型.研究内容为深入开展六维力传感器的弹性动力学分析与综合及动态优化设计奠定了基础.     

Output characteristics and experiments of a novel low frequency rotary piezoelectric motor

In order to improve the output performance of a piezoelectric motor under low driving frequency, a novel rotary piezoelectric motor driven by two piezoelectric actuators is proposed that is actuated based on harmonic and friction driving mechanism. The motor uses two piezoelectric actuators to drive two amplifying mechanisms with π/2 phase difference to produce harmonic motion, and then drives the rotor to rotate through friction force. Based on the driving principle, the electromechanical coupling equations of the motor are established. And a test platform is built to test the output characteristics of the motor. The results show that fluctuation of harmonic force and output torque occurs when the motor operates at different positions. Under the driving voltage and frequency of 150 V and 5 Hz, the actual average output torque of the prototype is 3.08 Nmm. Moreover, fluctuation of harmonic force and output torque occurs when the motor operates at different positions.

     

基于6维力/力矩传感器的并联机器人惯性参数辨识方法

提出了基于6维力/力矩传感器的并联机器人惯性参数辨识新方法,这种方法不需要了解关节摩擦和驱动器动力学特性的精确模型,推导了一般并联机器人的惯性参数辨识模型,分析了并联机器人的基惯性参数,提出了并联机器人惯性参数辨识轨迹的选择原则,并给出了两种新型空间并联机器人的分析实例。     

A novel self-decoupled four degree-of-freedom wrist force/torque sensor

Haptic based human–computer interaction (HapHCI) system is currently the frontier of robot research, which is widely used in virtual reality, rehabilitation, entertainment, and so on. The measurement of the multi-dimensional interactive force between human hand and interaction device such as hand-controller, joystick, limb rehabilitation device, etc., becomes an important component of the HapHCI. However, the existing commercial 6 degree-of-freedom (DOF) force sensors are too expensive and often over designed for HapHCI not only in axis but also in bandwidth. In this paper, a novel 4 DOF wrist force/torque sensor suitable for HapHCI is developed, which is self-decoupled without calculating the decoupling matrix. Thus this type of wrist force/torque can be called as direct output force sensor, which is quite different from the conventional ones called as indirect output force sensor. Its elastic body has a simple geometry which is easy to fabricate, and half the number of strain gauges compared to the existing commercial 6 DOF force/torque sensor. So the 4 DOF force/torque sensor is much lower in cost. This paper introduces the elastic body structure of the wrist force/torque sensors, and analyses the self-decoupled principle in detail. A prototype sensor is fabricated, and the calibration test results of the 4 DOF force/torque sensor validate the analysis and demonstrate the advantage of such a sensor.     

新型解耦和各向同性五维力传感器性能分析

介绍基于并联4-SPS&1-UPU结构的新型机器人五维力与力矩传感器的结构特点,并分析计算了其力与应变之间的转换关系及其力各向同性,为该五维力与力矩传感器的设计和使用提供了理论依据,分析计算结果表明该传感器是力与力矩解耦和各向同性的。该传感器采用弹性铰链替代球铰和虎克铰,具有结构灵巧、工艺好等优点,可应用到机器人手指和其他使用多维力与力矩传感器的场合。     

新型机器人6维力／力矩传感器结构的刚度性能指标分析

提出了一种新颖的6维力/力矩传感器并联结构,应用并联机器人机构学理论求出其刚度矩阵,定义其刚度性能指标,并对其刚度性能指标进行分析计算,为该传感器的设计与应用提供理论依据。分析计算结果表明,该并联结构的6维力/力矩传感器是位移刚度和扭转刚度各项同性的,可应用到机器人手腕、手指和其它使用多维力/力矩传感器的场合。     

基于非对称夹持的压电旋转驱动器设计

设计了一种新型非对称夹持压电旋转驱动器。通过对称性电信号激励粘贴在基板上的压电晶片,使基板自由端带动质量块非对称地往复摆动,进而产生非对称的惯性驱动力,实现压电旋转驱动器的定向运动。研制了非对称压电惯性旋转驱动器样机,搭建了驱动器的测试系统,对驱动器步长、摩擦力矩、载荷特性等进行了测试。结果表明,驱动器在电压为15V、频率为10Hz、夹持差为3mm时,步长分辨率为1.82μrad,摩擦力矩为2.475N·mm条件下的最大输出载荷为0.122N。     

基于晶体变形的压电石英测试理论研究与应用

对基于晶体变形的压电效应的研究现状和应用进行阐述和讨论。介绍了压电弯曲、扭转效应理论的研究进展,给出了在弯矩、扭矩作用下的束缚电荷和极化电场的分布规律;在理论研究的基础上,对所研发的新型微雕笔式执行器、扭矩传感器、钻削测力仪进行了介绍。基于晶体变形的压电效应的探索与开发对压电学体系的发展与完善以及工程应用都有重要的实用价值。     

压电式力传感器的低频补偿方法及实验验证

提出了一种压电式力传感器低频响应特性的补偿方法,该方法是在频域上完成的。首先,对压电式力传感器的输出信号进行后处理,将输出信号与补偿函数相乘即可获得补偿后的输出信号,其中,补偿函数是压电式力传感器放电时间常数的函数;然后,以P5H压电陶瓷片为例,分别对其施加已知的阶跃外力和低频简谐外力,并分别将补偿前后的测试结果与已知外力进行对比,从而实现对该方法的实验验证。验证结果表明:该方法可以对压电式力传感器的低频响应特性进行有效的补偿。     

过约束平面并联三维力/力矩传感器的研制

针对轴承的故障早期诊断和在线实时监测,提出了一种新型过约束平面并联三维力/力矩传感器。通过采用分支轴线均不过传感器中心的6条对称分布的测力分支,该传感器可同时测量轴承径向载荷和轴向力矩。根据静力学平衡方程,求解了其测量数学模型;基于传感器测量模型与性能指标分析了传感器性能,进而对其各结构参数进行优化设计。研制了传感器样机及其加载标定实验系统,开展了加载标定实验,得到了该传感器的测量精度。标定实验结果显示:传感器径向力测量精度为2.56%,力矩测量精度为0.92%,Ⅰ类误差为2.56%,最大Ⅱ类误差为2.29%。文中所做工作,为将该新型过约束平面并联三维力/力矩传感器应用于在线实时测量轴承径向载荷和轴向摩擦力矩奠定了基础。     

多维力/力矩传感器静态解耦的研究

多维力 /力矩传感器的静态耦合是影响其测量精度的主要因素之一。在研究基于最小二乘理论的多维力传感器静态线性解耦方法的同时 ,提出了一种基于 BP神经网络的静态非线性解耦方法。以 HIT灵巧手的微型五维指尖力 /力矩传感器为对象进行了实验 ,结果表明 ,基于神经网络的非线性解耦方法可以明显地提高传感器的测量精度     

Analyzing the drivers of end-of-life tire management using interpretive structural modeling (ISM)

A sensor module that incorporates a thin film polyvinylidene fluoride (PVDF) piezoelectric strain sensor rosette as well as data logging and wireless transmitting electronics has been designed and implemented for monitoring dynamic cutting torque in the end milling process—a material removal process widely used in the aerospace industry. The dynamic shear strain produced in the rotating tool during the cutting process is picked up by the PVDF sensor rosette attached to the tool shank and can be either logged into the onboard micro secure digital card or wirelessly transmitted to a nearby base station. The PVDF sensor rosette is largely insensitive to the pyroelectric effect of the PVDF sensor and the other strain components such as bending strain and thermal strain. A physics-based model is used to relate the measured PVDF sensor signal to the dynamic milling torque. The proposed method is experimentally validated using reference milling torque signals computed from cutting force signals measured using a platform-type piezoelectric force dynamometer.