1、 本科毕业 论文 外文文献 及译文 文献、资料题目： A Low-Cost, Smart Capacitive Position Sensor 文献、资料来源： IEEE TRANSACTIONS ON INSTRUMENT AND MEASUREMENT 文献、资料发表（出版）日期： 1992.12 院 （部）： 信息与电气 工程学院 专 业： 电气 工程 与自动化 班 级： 电本 064 - 1 - 外文 文献 ： A Low-Cost, Smart Capacitive Position Sensor Abstract A new high-performance, low-cost,
2、capacitive position-measuring system is described. By using a highly linear oscillator, shielding and a three-signal approach, most of the errors are eliminated. The accuracy amounts to 1 m over a 1 mm range. Since the output of the oscillator can directly be connected to a microcontroller, an A/D c
3、onverter is not needed. I. INTRODUCTION This paper describes a novel high-performance, low-cost, capacitive displacement measuring system featuring: 1 mm measuring range, 1 m accuracy, 0.1 s total measuring time. Translated to the capacitive domain, the specifications correspond to: a possible range
4、 of 1 pF； only 50 fF of this range is used for the displacement transducer； 50 aF absolute capacitance-measuring inaccuracy. Meijer and Schrier l and more recently Van Drecht,Meijer, and De Jong 2 have proposed a displacement-measuring system, using a PSD (Position Sensitive Detector) as sensing ele
5、ment. Some disadvantages of using a PSD are the higher costs and the higher power consumption of the PSD and LED (Light-Emitting Diode) as compared to the capacitive sensor elements described in this paper. The signal processor uses the concepts presented in 2,but is adopted for the use of capacitiv
6、e elements. By the extensive use of shielding, guarding and smart A/D conversion,the system is able to combine a high accuracy with a very low cost-price. The transducer produces three-period-modulated signals which can be selected and directly read out by a microcontroller. The microcontroller,in r
7、eturn, calculates the displacement and can send this value to a host computer (Fig. 1) or a display or drive an actuator. - 2 - Fig. 1. Block diagram of the system Fig. 2. Perspective and dimensions of the electrode structure . THE ELECTRODE STRUCTURE The basic sensing element consists of two simple
8、 electrodes with capacitance Cx, (Fig. 2). The smaller one (E2) is surrounded by a guard electrode. Thanks to the use of the guard electrode, the capacitance Cx between the two electrodes is independent of movements (lateral displacements as well as rotations) parallel to the electrode surface.The i
9、nfluence of the parasitic capacitances Cp will be eliminated as will be discussed in Section . According to Heerens 3, the relative deviation in the capacitance Cx between the two electrodes caused by the finite guard electrode size is smaller than: e-(x/d) (1) where x is the width of the guard and d the distance between the electrodes. This deviation xC Electronic Circuit C refC Personal Computer Actuator Display
