传动轴扭矩测量误差分析

传动轴扭矩测量是研究车辆动力系统性能的重要手段.介绍了传动轴扭矩精确测量的重要性,给出了影响传动轴扭矩测量精度的一些因素,并详细分析了由传动轴扭矩应变式测量方式、传动轴本身产生的弯矩以及传动系统带来的扭振对测试结果所产生的影响,为下一步更精确地测量传动轴的扭矩打下了坚实的基础.     

Novel non-contact torque measurement using the magnetomechanical effect

With the recent developments in science and technology, torque measurements have been widely used in many fields. However, present torque measurement methods have limitations for long-term applications. Therefore, a new method of non-contact torque measurement based on the magnetomachanical effect is reported that may be used in reducing fatigue for long-term measurements. The theory of the changes in magnetization with torque are analyzed to construct a model. Hence, an experiment platform was constructed that includes an excitation coils, shaft, and Gauss meter. The relationship between the magnetic induction and the torque was measured using this apparatus. The results show that the experimental measurements are in agreement with mathematical models obtained using magnetomechanical concepts. The results also show that the maximum nonlinearity error of the system is 0.6% and the maximum repetitive error is 3.125%. Additionally, this proposed method meets the requirements for long-term torque measurements and may also be used for the non-contact characterization of the torque of watercraft and airplanes.     

小型力矩电机波动力矩的测量

综合考虑现有无刷直流力矩电机波动力矩动静态测量方法的不足,提出了一种精确测量力矩电机波动力矩的方法。分析了力矩电机波动力矩经典测量方法的误差来源,根据力矩电机分体式的结构特点和可以长期堵转的性能特点,提出了采用电机定子相对转子旋转测量波动力矩的方法。在力矩电机转子堵转的状态下,通过外力旋转定子,测量电机堵转力矩的波动值,从而有效减少测量过程中惯性力矩和摩擦力矩引入的误差。根据提出的测量方法搭建了一套波动力矩测量装置,使用蜗轮蜗杆机构实现了定转子的相对旋转,并对测量装置进行了校准实验。实验结果表明,对于量程为0~1Nm的装置,其测量准确度可达0.3%,线性度为0.1%,基本满足无刷直流力矩电机对波动力矩测量的精度要求。     

The uncertainty of torque primary standards: a comprehensive analysis

The development of high-accuracy torque primary standards constitutes the first step towards the harmonisation of the unit of measurement and the realisation of a reliable traceability chain for torque transducers, torque wrenches and screwdrivers. In this paper, a detailed analysis of the uncertainty budget of torque primary standards is proposed. On the basis of the characteristics of the realisations set up by some of the European National Metrological Institutes, as they are available in the literature, the order of magnitude of the uncertainty such systems can achieve is derived. To this extent, attention has been focused on the main questions in the design and in carrying out the measurement of the quantities that determine the main contributions to the uncertainty. Particularly, from the latter point of view, an investigation on the measurement of the friction torque, which is responsible for the degradation of the metrological performances in the lower part of the working range, has been performed.     

Modeling and experimental evaluation of torque loss in turbine test rig for accurate turbine performance evaluation

The performance of a turbine is evaluated through a turbine rig test by measuring the torque or power generated from the test turbine using a dynamometer or torque sensor installed in the test rig. Highly precise assessment requires accurate measurement of the torque or power. However, an intrinsic difficulty exists such that not all power generated by the turbine is measured by the dynamometer or torque sensor. A small portion of power generated from the test turbine is dissipated between the test turbine and torque sensor as bearing and windage losses. The dissipated energy is called mechanical loss of test rig. Therefore, measuring the mechanical loss of the test rig is necessary for the accurate evaluation of the turbine performance. The present paper classifies mechanical loss into bearing, disk windage, and extra windage losses. Spin-down tests are performed in a 1-stage axial turbine test rig to evaluate each loss. The total mechanical loss amounts to 0.78% to 1.4% of energy generated at the turbine. Bearing loss is dominant. Mechanical loss is dependent on and increases with decreasing bearing temperature.     

Traceability of torque transducers under rotating and dynamic operating conditions

Torque transducers in industrial applications are usually used under dynamic and rotating operating conditions. The present article provides a survey of state-of-the-art studies which describe methods for providing traceability of torque measurements under such operating conditions.The method of investigating the effects of rotation is a comparison of measurements of torque in a rotating shaft train gained simultaneously with two different methods. The first method is using a rotating torque transducer, the second one is with a cradle-mounted absorption dynamometer. The method for investigating the effects of dynamic torque is based on experiments with periodic torque but only minimal rotational motion. Torque is generated by a rotary exciter which forces a setup with a torque transducer and some auxiliary components into a periodic rotary motion. The torque measurement provided by the torque transducer is compared to a reference torque. The reference torque is gained by accurately measuring the angular acceleration of the rotation in conjunction with a priori knowledge of the mass moment of inertia.The developments on the periodic dynamic torque have been performed by the Physikalisch-Technische Bundesanstalt (PTB), the German National Metrology Institute. The investigations on rotating torque transducers have been performed by Hottinger Baldwin Messtechnik (HBM), Germany, a manufacturer of torque transducers with a wide experience in torque calibration.     

摩擦力矩对扭矩标准机测量精度的影响

通过分析,可以看出杠杆自重及力值砝码重量引起的摩擦力矩,是影响轴承式扭矩标准装置测量精度的重要因素,而杠杆自重引起的摩擦力矩近似为常数,可以进行补偿或作为初始零值处理,从而可以显著提高扭矩标准装置的计量性能;采用陶瓷轴承制作的扭矩标准装置的不确定度理论上可以优于0.03%。     

Study on effects of negative driving torque in servomotor drivers

Many applications, such as elevators, electric cars and robotic applications, require a servomotor driver capable of controlling a motor to drive its load with either positive or negative driving torque. The negative driving torque is defined as torque applied to a load in the reverse direction of motor rotation. In a servomotor driver with a switching amplifier, when the motor drives its load with negative driving torque, effects of negative driving torque might damage the servomotor driver and complicate dynamic characteristics of the servomotor system. Thus, in order to investigate effects of the negative driving torque in servomotor drivers, this paper uses the numerical simulation that combines the simulation of a control system with that of electronic circuits. The simulation results show that the negative driving torque is required for decelerating and compensating disturbance. During decelerating and compensating disturbance, the pulse-width modulation (PWM) amplifier of a servomotor driver will generate regenerative current that flows from the motor back into the power supply, and then makes the power supply voltage rise.     

Measurement of active power by time domain digital signal processing

This paper compares DSP time domain algorithms of one-phase active power measurement by non-coherent sampling that are superior to some frequency domain algorithms in active power estimation of non-sinusoidal signals. The measurement bias, uncertainty and sampling time necessary for the required accuracy are compared for various data windows with the use of simulations and measurements. Both monofrequency and multifrequency signals are dealt with. Analytical formulas are presented for the active power bias for rectangular and general cosine windows and for standard uncertainty of active power measurement. A simple method is described for correction of the multiplexing delay in power measurement using multiplexing DAQ boards. The information from this paper can also be used for measuring energy consumption and three-phase power.     

螺管形差动变压器的非接触式扭矩传感器研究

扭矩测量是传动线路中的重要内容之一，高精度、高稳定性的非接触式扭矩测量方法是当今各国机械量测量研究的热点之一，为此，提出了一种基于螺管形差动变压器的非接触式扭矩传感器的研究。本文系统介绍了该测量方法的原理与结构，并对新研制的传感器进行了加载实验，从实验数据及其拟合方程证实该测量原理可行，所设计的扭矩传感器具有较好的线性度和一致性，重复精度≤0．5％。     

Estimation of turbine torque using an adaptive nonlinear observer for closed-loop control of vehicle automatic transmissions

This paper presents an adaptive sliding observer-based method for the estimation of turbine torque. The estimations of turbine torque can be used in the closed-loop control of vehicle power train for better shift quality. A sliding observer structure including saturation functions and boundary layers is applied to adapt torque converter parameters. The proposed method has been investigated via simulation and laboratory experimental studies. It has been shown via simulation and experiments that the proposed methodology is promising for the estimations of turbine torque since it uses only inexpensive angular velocity measurements and is not sensitive to parametric uncertainties.     

A novel measurement method for the torque acting on the upper platen in a three-way double-sided lapping/polishing machine

In double-sided lapping and polishing processes, the friction coefficients between the workpiece and platens or pads are important parameters for understanding or improving the lapping and polishing processes. However, the friction coefficients have not been investigated in detail owing to insufficient measurement methods for the torques acting on the upper and lower platens, which are necessary to evaluate the friction coefficients. Thus, a novel measurement method for the torque acting on the upper platen in a three-way double-sided machine was proposed in this study. In the method, the torque is measured based on the forces acting on the holders supporting the upper platen rotation. The torques were measured with the method in double-sided lapping experiments, and they were confirmed to agree with the theoretical torque variation. Furthermore, the friction coefficient between the workpiece and upper pad identified with the proposed method was also verified by comparing with the friction coefficient measured in the single-sided lapping experiment. In addition, the estimation method of the lower platen torque based on the motor torque was investigated by utilizing the proposed method, and we found the lower platen torque was estimated accurately by taking a sufficient warm-up time or by modeling the torque loss in transmission path. Therefore, accurate measurement of the torques acting on the upper and lower platens, which is an effective tool for understanding or improving the process, was realized.     

轻型汽车排放测量不确定度

检测中心是对企业产品质量控制起到至关重要作用的部门。为了确保检测中心能够保证其测量的可靠性,我们对其各设备的测量不确定度有非常严格的把控。结合实际试验,分析本检测中心轻型汽车排放及测功机扭矩的测量不确定度。     

MR fluid viscous coupling and its torque delivery control

A torque controllable viscous coupling is presented. The coupling consists of two types of discs with slits. One is connected to a housing (follower discs) and the other is connected to a shaft (driving discs). The driving discs and follower discs are arranged by turns and they are sandwiched. MR fluid is filled in the housing. Magnetic fields freeze the fluid, so that the shear torque is generated between the diving discs and follower discs due to shears between the slits in the discs under the magnetic fields. The torque is controlled by electromagnets. In order to have large torque with small electric power, coil turns have to be large, so that response delays due to inductance of the coil. A controller which improves response is presented. A method of control is presented which controls distribution of torque of rear wheel and front wheel.     

Modified uncertainty estimation of antenna factor measurement by standard site method

The standard site method was used to measure antenna factor. Based on calculation of antenna factor uncertainty, ways of more precise estimation of uncertainty, leading to uncertainty reduction, are presented. Using uncertainty standards together with known approaches to radiated emission measurement uncertainty calculation, a model of antenna factor measurement and an equation for calculation of its uncertainty were derived. Possible steps to reduce resultant measurement uncertainty are described, including an analysis of correlation, and acknowledgment of frequency dependence. The uncertainty was calculated in 25 frequency points in the range from 30 MHz to 1000 MHz. Furthermore, various calculations of uncertainty are executed to examine the suggested effects on the uncertainty value.     

MRAS state estimator for speed sensorless ISFOC induction motor drives with Luenberger load torque estimation

This paper presents a novel method for estimating the load torque of a sensorless indirect stator flux oriented controlled (ISFOC) induction motor drive based on the model reference adaptive system (MRAS) scheme. As a matter of fact, this method is meant to inter-connect a speed estimator with the load torque observer. For this purpose, a MRAS has been applied to estimate the rotor speed with tuned load torque in order to obtain a high performance ISFOC induction motor drive. The reference and adjustable models, developed in the stationary stator reference frame, are used in the MRAS scheme in an attempt to estimate the speed of the measured terminal voltages and currents. The load torque is estimated by means of a Luenberger observer defined throughout the mechanical equation. Every observer state matrix depends on the mechanical characteristics of the machine taking into account the vicious friction coefficient and inertia moment. Accordingly, some simulation results are presented to validate the proposed method and to highlight the influence of the variation of the inertia moment and the friction coefficient on the speed and the estimated load torque. The experimental results, concerning to the sensorless speed with a load torque estimation, are elaborated in order to validate the effectiveness of the proposed method. The complete sensorless ISFOC with load torque estimation is successfully implemented in real time using a digital signal processor board DSpace DS1104 for a laboratory 3 kW induction motor.     

基于EKF的异步电机转速和负载转矩估计

合理选择电机的容量具有重要的意义,电机的容量可根据电机的转速和负载转矩确定,将电机的转速和负载转矩同时作为系统的状态,提出了一种基于EKF同时估计异步电机转速和负载转矩的方法,建立了包含异步电机转速和负载转矩状态的系统模型,基于该模型用EKF实现了同时估计异步电机转速和负载转矩,仿真和实验验证了所提方法能以较高的精度同时估计出电机的转速和负载转矩.     

扭矩测量仪现场校准方法的探讨

通过分析扭矩测量仪的量值传递现状,从测试和校准两种情况,探讨分析了扭矩测量仪现场校准的方法以及测量结果不确定度的评定方法,确保扭矩测量仪现场校准的准确与可靠。     

电机转矩转速测量方法的分析

电机的转矩和转速是最重要的两个参数,对它们的测量必须准确.根据用户提出的测量航空电机具体要求,本文分析了转矩和转速的测量原理,指出了采用应变式和光电式传感器构成测量仪更适合测量大转矩、高转速电机.虽然与传统的测量方法一致,但经过理论分析,得出了这种测量方式机械结构影响测量稳定性的原因,即传动轴受减速器齿轮啮合力作用产生的弯曲应变和结构谐振对测量精度影响最大.本文通过精确的计算,充分地考虑了机械结构对测量稳定性的影响,提出了选择转矩传感器及转速传感器的基本原理与方法.据此,在所研制的电机测量仪中,大大地提高了测量精度,并有效地减小了测量仪的体积和重量,适合航空工业应用.     

电磁式扭矩传感器原理、研究现状及发展趋势

电磁式扭矩传感器可实现对扭矩的非接触式测量,该传感器具有精度高、抗干扰能力强、无需额外电源和易于安装的诸多优点,非常适合高温、高湿、粉尘极端环境下的扭矩测量。介绍并围绕电磁式扭矩传感器的工作原理,明确归纳了电磁式扭矩传感器的涵盖类别并给出了几款具有代表性的电磁式扭矩传感器。结合国内外30年来电磁式扭矩传感器的发展情况,根据测量扭矩量程大小的技术特点分类阐述,详细论述了其在传统汽车、船舶、航空等行业的应用及研究现状,并对新兴行业:生物医学、医疗器械、机器人行业的应用及研究现状进行了阐述。分析了制约电磁式扭矩传感器发展所存在的问题及其改进方向,最后归纳并阐述了此类电磁式扭矩传感器的发展趋势。