新型过约束正交并联六维力传感器测量模型与静态标定试验

面向航空航天领域对重载大吨位多维测力传感器的急需,通过引入冗余测力分支,提出一种适用于重载测力场合的新型过约束正交并联六维力传感器结构,在提高传感器结构刚度和承载能力的同时有效抑制了关节摩擦对多维力传感器测量精度的影响。基于螺旋理论,推导得到了该并联传感器一阶静力影响系数矩阵,建立理想状态下该新型过约束正交并联六维力传感器测量数学模型。考虑各测量分支的初始预紧力与刚度,基于传感器静力平衡方程与补充建立的位移协调方程,推导建立考虑初始预紧力与分支刚度因素下该新型过约束正交并联六维力传感器测量数学模型。在此基础上,设计并研制该新型过约束正交并联六维力传感器样机,搭建传感器加载标定与信号采集及处理试验系统,对新型过约束正交并联六维力传感器进行了加载标定试验。根据试验结果计算了传感器测量误差矩阵,分析得到了传感器测量精度,从而为重载过约束并联六维力传感器的开发与应用提供了参考。     

正交并联六轴力传感器耦合误差测量模型及实验分析

为解决并联六轴力传感器量程提升受限问题,设计了一种正交构型并联六轴力传感器。正交并联六轴力传感器是基于并联六轴力传感器的一种构型上的改进,具有承载能力强、解耦性能良好的优势,但同时该力传感器的耦合误差输出具有自身的特点。考虑该力传感器测量分支间摩擦以及正交结构自身特点引起的耦合误差输出,建立了正交并联六轴力传感器耦合误差测量模型。基于所建立的测量模型,通过数值算例分析探讨了传感器设计参数与两种耦合误差输出之间的影响关系,据此研制了一种正交并联六轴力传感器。最后对传感器样机进行了实验,得到其误差分布及检验测量精度。实验所得传感器各维力/力矩在各方向误差分别为0.43%/0.31%,0.18%/0.68%,0.80%/1.28%。     

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。     

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.     

空间对接半物理仿真原型试验系统

为研制用于对接机构地面测试的空间对接半物理仿真系统,建立能够体现其主要功能的原型试验系统。试验系统通过六维力传感器检测对接机构模拟元件的相互作用力和力矩,根据所建立的航天器动力学模型实时解算对接过程中两航天器的相对运动,并由6自由度运动平台模拟被动航天器来实现此相对运动。针对此原型试验系统,提出系统的动力学解算方案并据此构建动力学仿真大回路,着重对大回路仿真系统的稳定性进行分析,得到稳定性条件,讨论运动平台滞后对仿真的影响和解决方法。在此基础上,用所研究系统成功地模拟了航天器对接的全过程,从而为实际空间对接半物理仿真系统提供了必要的设计依据。     

Research on force-sensing element's spatial arrangement of piezoelectric six-component force/torque sensor

This paper proposes a novel piezoelectric six-component force/torque sensor with four-point supporting structure, and makes research on force-sensing element's spatial arrangement of the novel sensor. Two kinds of different spatial arrangements are advanced, lozenge and square arrangement. The mathematical models are built and calculated. The influence on using performance of the two kinds of different spatial arrangements of the sensor is analyzed by FEM (ANSYS software). In order to investigate the validity of the proposed method, a prototype of piezoelectric six-component force/moment sensor is developed with two kinds of different spatial arrangements, and characteristic tests of the piezoelectric six-component force/moment sensor are performed. The test shows that both of the different spatial arrangement sensors could be used to measure six-component force/torque, but the square arrangement piezoelectric six-component force/moment sensor is more suitable for measurement of six-component force/torque on axis. The interference errors of square arrangement sensor are less than 5%, which are lower than those of the lozenge arrangement sensor. The natural frequencies in six directions are analyzed and discussed.     

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。     

Optimal design and experiment research of a fully pre-stressed six-axis force/torque sensor

This paper presents the design and experiment of a fully pre-stressed six-axis force/torque sensor with double layers. The structure characteristic of the fully pre-stressed six-axis force/torque sensor is introduced in comparison with the traditional Stewart platform-based force sensor. In order to meet the expected task requirements, an optimal design approach based on the given measurement range of the sensor is proposed with the aim of minimizing the forces of the measuring limbs overall. Considering the optimization objective, the optimal solutions of the structural parameters are obtained. Finally, the sensor prototype is manufactured and the calibration system is developed. The calibration experiment is performed and the results prove the superiority of the sensor structure and the validity of the optimal design method.     

Torque sensor calibration using virtual load for a manipulator

Accurate load sensing of a manipulator becomes increasingly important in performing various tasks involving contact with an environment. Most of the research has been focused on improving the hardware of a force/torque sensor. The torque sensors for a manipulator suffer from crosstalk, which is difficult to compensate for even with sophisticated calibration. This research proposed a novel calibration method composed of two steps. Through the primary calibration, the torque sensor output can be related to the joint torques. The secondary calibration, which is based on a virtual load, is conducted to compensate for the crosstalk of a torque sensor. The virtual load is obtained from the sensed joint torques and manipulator configuration. Using the proposed calibration method, the external load acting on the end-effector of a manipulator can be accurately measured even with relatively low-quality torque sensors. The experimental results showed that the error in the load sensing was significantly reduced by the proposed calibration method.     

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.     

Crosstalk calibration for torque sensor using actual sensing frame

Accurate load sensing is crucial to robots’ performance of various tasks undertaken to assist workers. Most of the research on load sensing by robot manipulators has focused on improving force/torque sensor hardware. Torque sensors suffer from crosstalk, which cannot be compensated, not even through calibration. Thus, for minimization of crosstalk, torque sensors require precise machining and a complicated structure, which often increase costs. This paper proposes an alternative, novel calibration method. In this scheme, first, the compliance matrix of the torque sensor is obtained from sampling data, and then the location and scale of the actual sensing frame, in which crosstalk-free load sensing occurs, can be estimated. Using the proposed calibration method, the external load acting on the end-effector can be sensed accurately, even with relatively low-quality torque sensors. Experimental results show that measurement accuracy was significantly improved with the proposed method.     

基于Stewart机构的六维力/力矩传感器

基于Stewart机构的六维力/力矩传感器是一种十分优越的测力传感器,具有测力接触面大、承载能力强、量程大、测力信息丰富等优点,可被广泛应用在航空机器人、航空航天技术及宇宙空间器的对接试验、风洞试验等场合。根据以上特点,阐述Stewart机构的六维力/力矩传感器的测力原理,分析传感器的受力变形,零部件设计尺寸和理论尺寸的制造误差及安装误差对其测力精度的影响,并对其结构参数进行优化设计。提出一种标定方法,研究其标定算法。对自主研制的Stewart六维力/力矩传感器进行标定试验,得出该传感器的标定矩阵。研究结果表明,用标定矩阵代替传感器理论影响系数矩阵参与6个单向力传感器输出信号的耦合,能够有效地提高该传感器的测力精度。     

二自由度球面并联机构UP+R静力学分析

采用拆杆法建立了机构的静力学平衡方程,考虑构件弹性,利用小变形叠加原理建立了机构的变形协调补充方程,进而完成了二自由度球面并联机构UP+R的静力学分析。通过计算,得到在三种载荷下构件上各力、输入转矩与机构位姿的关系图。结果表明,仅在外力作用下,机构的输入力矩恒等于零,构件上的力随机构位姿的变化比较平缓,仅在外力矩作用下,机构的输入力矩、构件上的力随着机构位姿的变化与机构的特性相关。力与力矩在构件上所产生的两部分力是独立的,并可以分离。研究结果为该机构在工程中的结构设计与应用提供了静力学理论基础和依据。     

HIT／DLR灵巧手传感器系统

介绍了HIT／DLR多指灵巧手的传感器系统,基于DSP,FPGA及A／D转换芯片等,实现了手指传感器信息的数字化采集和传输,提高了传感器的信号质量及系统可靠性。在灵巧手的传感器系统中,着重介绍了指尖六维力／力矩传感器、关节位置传感器、关节力矩传感器及触觉传感器等。     

Workspace and statics analysis of 4-UPS-UPU parallel coordinate measuring machine

A novel 4-UPS-UPU spatial 5-Degree of freedom parallel coordinate measuring machine (PCMM) is presented. The workspace of the measuring machine is analyzed by using polar coordinate searching method. The force balance equation and statics transfer matrix of the measuring machine are established. The statics analysis of the 4-UPS-UPU PCMM is realized by taking the PCMM with load and no-load as example, and the numerical verification and virtual simulation verification of the results of driving force are carried out. The research can provide a theoretical basis for the optimal design and manufacturing of 4-UPS-UPU PCMM.     

新型球面并联人形机器人踝关节机构静力学性能分析

采用拆杆法建立机构的静力学平衡方程,考虑构件弹性,利用小变形叠加原理建立机构的变形协调补充方程,进而完成二自由度并联人形机器人踝关节机构的静力学分析。通过数值计算,得到在三种外载荷下构件上的各力与机构位姿的关系图。结果表明:外载荷为纯力时,支链1的受力很小,支链2的受力近似为零,而中心球面副支链的受力近似等于外载荷;外载荷为纯力矩时,三个支链的受力情况相似;外载荷为力和力矩时,支链1、支链2的受力情况与外载荷为纯力矩时的受力情况相似,中心球面副支链的受力为前两种情况的叠加。外载荷中的力成分主要由中心球面副支链承载,力矩成分由三个支链共同承载。该研究为该人形机器人踝关节机构在工程中的结构设计与应用提供了静力学参考。     

一种用于MEMS样品测试的六轴微力传感器

本文研制了一种用于MEMS样品测试的六轴微力传感器。首先采用有限元法对特定结构的传感器进行了静力学分析 ,确定了其布片方案 ;然后通过软件实现对传感器输出进行六轴力 /力矩的解耦 ,这大大简化了后置解耦电路的设计并降低了成本 ;最后本文给出了六轴微力传感器的标定曲线 ,证明其可用于MEMS做样品力学特性测试。     

基于六自由度机器人的航天服性能参数测试

介绍了一种基于六自由度测量机器人的航天服性能参数测试系统的测量原理，基于机器人运动学和静力学原理建立了随动式机器人和舱内航天服（IVA)三自由度手臂软关节的数学模型，分析了机器人的工作空间，有效地证明了测试原理的正确性。     

新型压电式测力仪多功能静态标定平台的研制

为了解决压电测力仪的静态标定,文中介绍了自行研制的高精度、高刚性静态标定平台原理与结构。该标定台垂直力、水平力均采用螺旋加载方式,力值大小由三级标准测力环直接读取;而扭矩的加载采用"力×力臂"法,通过平移两个水平加载机构形成力臂,同时产生大小相等、方向相反的两个力来实现。对该标定台进行精度和刚度实测,结果表明相关指标均达到了CIRP-STCC标准。无疑,利用该标定平台可完成单向、双向力传感器、三向压电式测力仪以及钻削测力仪的静态灵敏度、线性、重复性、滞后以及横向干扰标定。     

Effect of elastomer characteristics on fiber optic force sensing performance in biomedical robotics applications

Miniaturized and “smart” sensors are required for research in biology, physiology, and biomechanics, and they have extremely important clinical applications for diagnostics and minimally invasive surgery. Fiber optic sensors have been proven to provide advantages compared to conventional sensors and high potential for biomechanical and biomedical applications. They are small, easy to operate, minimally invasive with low risk, more accurate, and inexpensive. This paper reports the design and modeling of a fiber optic force sensor that is capable of measuring compliance for a contact force of up to 1 N. The main objective of this study is to design and model a fiber optic sensor capable of measuring the total force applied on an object. A polydimethylsiloxane (PDMS) elastomer film with a thickness of 1.2 mm is placed between an optical fiber tip and an object, and it is used for measuring the force applied on a rigid element. The compliance of the fiber optic force sensor is measured by recording the response of PDMS elastomer films under different load conditions. We use finite element modeling results as a basis for comparing experimental data. The agreement between theoretical predictions and experimental data is reasonable and within an acceptable range.