| 摘要 |
An absolute position measurement capacitive grating displacement measurement method, a sensor, and an operating method of the sensor are provided. In the measurement method, a drive signal having wave properties is used to excite a transmission grating, and displacement of a measured position in each wavelength is transformed into an initial phase of a time fundamental wave. The displacement of the measured position in each wavelength is acquired through an addition counter. A signal having wave properties output by a drive signal generator of the sensor is connected to a transmission grating, the master clock of an oscillator is connected to each circuit, an output of a reception grating is connected to a synchronous capture circuit through a signal selection switch and an analog processing circuit; and the synchronous capture circuit is connected to a controller, an addition counter, and a Random Access Memory (RAM). The controller is connected to all components. In the operating method of the sensor, an interface unit starts a measurement unit, a controller coordinates operation of all circuits, and after measurement of displacements in coarse, medium, and fine wavelengths is successively completed, the interface unit turns off the measurement unit, performs processing, and displays the measurement result. The circuits are simple, easy to control, and easy to be realized, and have high precision. |
| 主权项 |
1. An absolute position measurement capacitive grating displacement measurement method, comprising:
exciting, by a sensor drive signal having wave properties, each electrode of a transmission grating, wherein the sensor drive signal having wave properties is changed into a received signal changing periodically with time after capacitive coupling of the transmission grating and a reflection grating, pitch conversion of the reflection grating and a conversion grating, and capacitive coupling of the conversion grating and a reception grating, displacement of a measured position in each wavelength is transformed into an initial phase of a time fundamental wave of a received signal, the time difference between a negative-to-positive zero-crossing point of the fundamental wave signal and a preset phase zero point is the displacement of the measured position in a measured wavelength, and the time difference is acquired by counting with an addition counter, so the displacement of the measured position in the measured wavelength is acquired, wherein the method is performed by an absolute position measurement capacitive grating displacement sensor that comprises: a transmission board; a reflection board capable of moving relative to each other; and a measurement circuit, wherein a column of periodically arranged electrodes are disposed on the transmission board in a measurement axis direction, which form a transmission grating, a column of periodically arranged electrodes are disposed on the reflection board in the measurement axis direction, which form a reflection grating, two columns of periodically arranged electrodes orderly connected to the reflection grating are further disposed on the reflection board, which form a conversion grating, two columns of periodically arranged electrodes for capacitive coupling with the conversion grating are further disposed on the transmission board, which form a reception grating, each N electrodes of the transmission grating form a group, N is an integer, 3≦N≦16, the electrodes are periodically arranged at intervals of Pt/N, an electrode pitch of the transmission grating having N electrodes in a group is Pt, Pt is Nt times of a fine wavelength Wf, and Nt is an odd number between 3 and 7, the electrodes of the reflection grating are divided into two groups alternately and periodically arranged at intervals of Pr, where Pr=Wf, the conversion grating electrodes on the reflection board are arranged along the measurement axis at respective intervals periodically, the two groups of electrodes of the reflection grating are orderly connected to the two columns of conversion grating electrodes respectively by wires, the measurement circuit comprises an interface unit and a measurement unit, the interface unit comprises a timer, a keyboard interface circuit, a measurement interface circuit, a display drive circuit, and an Arithmetic Logic Unit (ALU), and the measurement unit comprises a drive signal generator and a signal processing circuit, and wherein the measurement unit further comprises an oscillator, a frequency divider, and a controller, the drive signal generator is a drive signal generator for generating a sensor drive signal having wave properties, a master clock output by the oscillator of the measurement unit is connected to the drive signal generator through the frequency divider, N output signals of the drive signal generator respectively are connected to N electrodes in each group of the transmission grating, the signal processing circuit of the measurement unit comprises: an analog processing circuit, a zero-crossing detection circuit, a synchronous delay circuit, an addition counter, a synchronous capture circuit, and a Random Access Memory (RAM), the analog processing circuit comprises a signal selection switch group, a differential amplifier, a synchronous demodulation circuit, and a low-pass filter, two outputs of the reception grating of the measured wavelength are connected to the differential amplifier through the signal selection switch group, after differential amplification, are then successively connected to the synchronous demodulation circuit, the low-pass filter, and the zero-crossing detection circuit, and then are input into the synchronous capture circuit, the master clock output by the oscillator is further connected to the controller, the synchronous demodulation circuit, the synchronous capture circuit, and the addition counter, a phase synchronization signal of the drive signal generator is connected to the synchronous delay circuit, an output of the synchronous delay circuit is connected to the synchronous capture circuit and the addition counter, an output of the zero-crossing detection circuit is connected to the synchronous capture circuit, an output of the synchronous capture circuit is input into the controller and the RAM at the same time, an output of the addition counter serves as a data input of the RAM, the measurement interface circuit of the interface unit is connected to the controller of the measurement unit and the RAM, outputs of the controller generating various control signals respectively are connected to the RAM, the drive signal generator, the signal selection switch group, and the measurement interface circuit of the interface unit, and an input terminal of the controller is connected to an output terminal of the synchronous capture circuit, and the master clock output by the oscillator is connected to a clock input terminal of the controller. |
