電動輔助轉向系統之非接觸式扭力感測器研發

A Study of Wireless Torque Sensing for EPS Based on SAW Sensors

林志哲(Chih-Jer Lin) ； 林海平(Hai-Ping Lin) ； 洪智偉(Chih-Wei Hung)

《車輛工程學刊》 7期 (2010/04) Pp. 49-67

https://doi.org/10.30023/JVE.201004.0004

摘要

本篇文章主要描述一套裝設於旋轉軸上之表面聲波元件(Surface Acoustic Wave, SAW)之扭力感測器的無線聲波量測，利用8051單晶片系統控制市售之RF晶片作爲發射端與接收端，並針對SAW的特性設計中心頻率搜尋程式。研究目的是在轉向軸受扭力變化時可即時量測出其變化程度，以即時監測的方式應用於車輛電子輔助轉向系統。當扭力桿受扭力時透過偶合天線傳送出所受扭力大小之訊號，其訊號使用RSSI強度來判斷SAW當時的中心頻率值，並與未受力時之狀態比較，計算出頻率漂移程度。無線部份以耦合天線裝設於旋轉軸上，不會受旋轉影響訊號的傳遞。

關鍵字

SAW ； 扭力感測器 ； RF ； 8051 ； RSSI ； EPS

並列摘要

The steering system can also affect the vehicle safety and improve the driver's effort. Traditional steering systems are mechanical systems which have complex mechanisms and steering force cannot be controlled effectively. Recently, electric power steering systems (EPS) are developed to compensate the transmitted steering forces according to the applied torque. To measure the torque via wireless sensing, the purpose of this paper is to propose a architecture based on two SAW sensors via wireless RF signals. In this implementation, the SAW sensors are attached on a rotational axis and micro chip 8051 is used to control the RF chips (C1100) to achieve the transmitting and receiving task. Measuring the shift of the center frequency of SAW sensors can be used to obtain the applied torque of the rotation axis. The measuring system mainly uses the RSSI signal with respect to the frequency to find the SAW center frequency value, and then the value of frequency shift can be transferred to the torque values. Besides, to achieve the wireless transmission, a coupling-type antenna is applied on the axis. Finally, the torque signal is passed through CANBUS to integrate with the other vehicles electron systems.

並列關鍵字

SAW ； Torque Sensor ； 8051 ； RF ； RSSI ； EPS