Basic study on a Self-tuning method for obtaining highly stable, general-purpose shaft torque sensors

获得高稳定通用轴扭矩传感器的自整定方法的基础研究

基本信息

批准号：
10450160
负责人：
SASADA Ichiro
金额：
$ 4.99万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Magnetostrictive effect inherent in the steel shaft provides noncontacting means of detecting torque applied to the shaft. A problem encountered in this scheme is low accuracy due to magnetic inhomogeneities being inevitable for the case-hardened steel shaft. Our torque sensor consists of induction hardened SNCM steel shaft (25 mmφ) and a magnetic head with a pair of planar figure-of-eight pickup coils embedded in a ferrite core. The objective of this research project is to study factors affecting the accuracy of the torque sensor and to find methods of reducing influence of the factors or to improve accuracy of the torque sensor. Results are summarized below :1. Reduction of zero-level-fluctuationZero-level-fluctuation of the torque sensor is strongly dependent on the balance of the inductance-resistance bridge, which is a main building block of the torque sensor. When the bridge is unbalanced, zero-level-fluctuation is enhanced. A bridge was tuned with a variable resistor connected p … More arallel to one of the pickup coils. With numerical simulation, this tuning condition is found to be unique, that is, global minimum in terms of the root mean square error. However, the tuning condition for a minimum zero-level-fluctuation does not meet, in general, the condition for a minimum offset. We indicated a method to avoid this problems, in which dummy impedance components having averaged values of those of active heads are to be used in the counter branch of the bridge circuit.2. Drift due to ambient temperatureObserving temperature variation of the permeability of each component used in the torque sensor, the most responsible component for the temperature stability is found to be casehardened steel shaft. This is due to the relaxation of compressive stresses in the case region of the shaft due to thermal expansion. Drifts of the torque sensor are observed in a temperature range from 40℃ to 140℃ for various initial offsets. It is found that the drift becomes smaller for smaller initial offset. As an example, temperature drift was -22% for an initial offset of 0.047% normalized to the excitation voltage and was reduced to -7.5% for an initial offset of 0.013%.3. Eddy currents effect on the zero-level stabilitySensing coils induce eddy currents on the surface of the steel shaft. We investigated the influence of the eddy currents on the zero-level stability taking the excitation frequency as a parameter. We found that zero-level perturbs over several period of revolution when the excitation frequency is low and that this phenomenon disappears when the excitation frequency is higher than ten times of the rate of revolution per second. Less

钢轴固有的磁致伸缩效应提供了非接触式检测施加到轴上的扭矩的方法，该方案遇到的问题是由于表面硬化钢轴不可避免地存在磁性不均匀性，因此我们的扭矩传感器由感应硬化 SNCM 钢制成。该研究项目的目的是研究影响扭矩精度的因素。研究结果总结如下：1．减少零位波动扭矩传感器的零位波动取决于传感器的平衡。电感电阻电桥，这是扭矩传感器的主要组成部分，当电桥不平衡时，零电平波动会通过连接到其中之一的可变电阻进行调谐。通过数值模拟，发现该调谐条件是唯一的，即均方根误差的全局最小值，但是，一般来说，不满足最小零电平波动的调谐条件。，最小偏移的条件。我们提出了一种避免此问题的方法，其中在桥电路的计数器分支中使用具有有源磁头平均值的虚拟阻抗组件。2。环境温度观察温度变化根据扭矩传感器中使用的每个部件的磁导率，对温度稳定性影响最大的部件是表面硬化钢轴，这是由于轴的热膨胀导致的压应力松弛。在 40℃ 至 140℃ 的温度范围内对各种初始偏移进行观察，发现初始偏移越小，漂移就越小。例如，初始偏移为 -22%。 0.047% 归一化为激励电压，初始偏移为 0.013%。3. 涡流对零电平稳定性的影响我们研究了钢轴表面感应涡流的影响。以激励频率为参数的涡流对零电平稳定性的影响我们发现，当激励频率较低时，零电平扰动会在多个旋转周期内发生。当励磁频率高于每秒转速的十倍时，现象消失。