阅读说明：本技术 基于数字电位计的绝对式测圈光电编码器 (Absolute measuring ring photoelectric encoder based on digital potentiometer ) 是由 韩庆阳 于 2020-07-22 设计创作，主要内容包括：基于数字电位计的绝对式测圈光电编码器,涉及光电编码器领域,解决现有绝对式测圈光电编码器体积大,转速受限和装调复杂等问题,光源发出的光经过指示光栅和主光栅后由光电接收管接收,光电接收管探测获得的粗码信号直接传送至MCU主控芯片的AD模块,探测获得的精码信号经放大电路放大后传送至MCU主控芯片的AD模块；MCU主控芯片对AD模块采集的信号进行处理,获得编码器的角位移；并将编码器的旋转圈数则转换成数字电位计的阻值,数字电位计的阻值通过补偿校准电路校准后,获得校正后的数字电位计的阻值；MCU主控芯片获得的角位移和圈数信息传送至上级系统。本发明的光电编码器体积小,装调简单。(An absolute measuring ring photoelectric encoder based on a digital potentiometer relates to the field of photoelectric encoders and solves the problems of large volume, limited rotating speed, complex installation and adjustment and the like of the existing absolute measuring ring photoelectric encoder; the MCU main control chip processes the signals acquired by the AD module to obtain the angular displacement of the encoder; the number of rotation turns of the encoder is converted into the resistance value of the digital potentiometer, and the resistance value of the digital potentiometer is calibrated through the compensation calibration circuit to obtain the corrected resistance value of the digital potentiometer; angular displacement and circle number information obtained by the MCU main control chip are transmitted to a superior system. The photoelectric encoder of the invention has small volume and simple installation and adjustment.)

1. The absolute measuring ring photoelectric encoder based on the digital potentiometer comprises a grating system, a mechanical shaft system and a processing circuit; the method is characterized in that: the processing circuit comprises a photoelectric receiving tube, an MCU main control chip, a digital potentiometer and a compensation calibration circuit;

light emitted by the light source passes through the indication grating and the main grating and is received by the photoelectric receiving tube, a coarse code signal obtained by detection of the photoelectric receiving tube is directly transmitted to the AD module of the MCU main control chip, and a fine code signal obtained by detection is amplified by the amplifying circuit and is transmitted to the AD module of the MCU main control chip;

the MCU main control chip processes the signals acquired by the AD module to obtain the angular displacement of the encoder; converting the number of rotation turns of the encoder into the resistance value of the digital potentiometer, and obtaining the corrected resistance value of the digital potentiometer after the resistance value of the digital potentiometer is calibrated by the compensation calibration circuit;

and the angular displacement and the circle number information obtained by the MCU main control chip are transmitted to a superior system.

2. The digital potentiometer-based absolute-type circle-measuring photoelectric encoder according to claim 1, wherein: the resistance value of the digital potentiometer is set through an SPI bus of the MCU main control chip.

3. The digital potentiometer-based absolute-type circle-measuring photoelectric encoder according to claim 1, wherein: the method for calibrating the resistance value of the digital potentiometer by the compensation calibration circuit comprises the following steps:

adding constant current source at two ends of the digital potentiometer, wherein the constant current source provides current I, and when the resistance drift does not occur, the voltage at two ends of the resistance AB is V_refSaid voltage V being_refAre known constants; the voltage across the resistor BC is V_out(ii) a When resistance drift occurs, the voltage of the AD acquisition module of the MCU main control chip after the drift occurs at the two ends of the resistor AB is V'_refVoltage V 'after drift of resistance BC'_outAnd a voltage V 'after the drift of both ends of the BC'_outAnd calibrating to obtain the voltage at the two ends of the corresponding resistance BC which does not drift as follows:

4. the method for measuring by an absolute type measuring ring photoelectric encoder based on a digital potentiometer according to claim 1, which is characterized in that: the method is realized by the following steps:

after power is on, the MCU main control chip initializes and then acquires coarse code and fine code signals, and performs coarse code decoding and fine code subdivision processing to obtain absolute angular displacement;

step two, the resistance value of the digital potentiometer is collected and corrected by the MCU main control chip, and the resistance value is counted by the number of turns of the encoder in last power failure; taking the absolute angular displacement obtained in the step one as the rotation angle of the encoder when the power is down last time;

calculating the rotation angle after power-on, acquiring data in real time by an AD module, and performing coarse code decoding and fine code subdivision operation by an MCU main control chip to obtain absolute angular displacement;

step four, judging whether the encoder rotates for a whole circle, if the encoder rotates for a whole circle in the forward direction, adding 1 to the number-of-turns counter, otherwise, subtracting 1, and realizing the measurement of the number of the rotating turns; sending the data of the number of rotation turns to a digital potentiometer through an SPI bus, and converting the data into resistance values; the resistance value of the resistor is the number of rotation turns; the photoelectric encoder has the function of measuring the absolute rotation number and the angle.

5. The method for measuring by a digital potentiometer absolute type ring measuring photoelectric encoder according to claim 4, further comprising the step of sending the data of the absolute angular displacement obtained in the step three and the rotation number obtained in the step four to a superior system through a communication module.

Technical Field

The invention relates to the field of photoelectric encoders, in particular to an absolute measuring ring photoelectric encoder based on a digital potentiometer.

Background

The photoelectric encoder is a digital angle measuring device integrating light, machine and electricity into a whole. The measurement mechanism can be divided into: the present invention is directed to a moire fringe type photoelectric encoder. The coding method can be divided into: incremental, absolute and quasi-absolute. After the absolute photoelectric encoder is powered off, data is not lost, and the power-on is the absolute angular displacement position of one circle. Has the advantages of stable and reliable work and the like, thereby being widely used. However, in many cases, if the linear displacement of the motor needs to be powered down to store the rotation number of the current encoder, the current absolute linear displacement position can be determined only by knowing the rotation number of the last encoder and the absolute angular displacement after the motor is powered up. It is therefore necessary to obtain both an absolute angular displacement of one revolution and an absolute number of revolutions.

At present, the photoelectric encoder with the function of measuring the number of absolute rotating turns and the angle is realized by matching gear transmission with two absolute photoelectric encoding disks, the method needs a high-precision gear transmission mechanism, is large in size, is limited in rotating speed, needs to consider the correction relation between the two absolute photoelectric encoding disks, and is complex to assemble and adjust.

Disclosure of Invention

The invention provides an absolute type measuring ring photoelectric encoder based on a digital potentiometer, which aims to solve the problems of large volume, limited rotating speed, complex assembly and adjustment and the like of the existing absolute type measuring ring photoelectric encoder.

The absolute measuring ring photoelectric encoder based on the digital potentiometer comprises a grating system, a mechanical shaft system and a processing circuit; the processing circuit comprises a photoelectric receiving tube, an MCU main control chip, a digital potentiometer and a compensation calibration circuit;

light emitted by the light source passes through the indication grating and the main grating and is received by the photoelectric receiving tube, a coarse code signal obtained by detection of the photoelectric receiving tube is directly transmitted to the AD module of the MCU main control chip, and a fine code signal obtained by detection is amplified by the amplifying circuit and is transmitted to the AD module of the MCU main control chip;

the MCU main control chip processes the signals acquired by the AD module to obtain the angular displacement of the encoder; converting the number of rotation turns of the encoder into the resistance value of the digital potentiometer, and obtaining the corrected resistance value of the digital potentiometer after the resistance value of the digital potentiometer is calibrated by the compensation calibration circuit;

the invention has the beneficial effects that: the invention is realized by adding a digital potentiometer and a compensation calibration circuit thereof to measure the absolute rotation number and angle during electric signal processing. The method is based on the pure electric signal processing, only a plurality of components are added in the circuit, so that the complex mechanical design and adjustment are avoided, and the size of the encoder is effectively reduced; meanwhile, the output of the digital potentiometer is compensated through the precise voltage stabilization chip, and the counting error of the absolute rotation number caused by the drift of the resistance value of the digital potentiometer is prevented.

The invention adopts a digital potentiometer to realize the measurement of the rotation number of turns of an absolute photoelectric encoder from the angle of electric signal processing. The method does not need to add mechanical parts, and the mechanical structure of the method is consistent with that of a common absolute photoelectric encoder. The extra mechanical debugging process is not added, the requirements on debugging personnel are reduced, and the work efficiency of debugging is improved. Compared with the traditional absolute measuring ring photoelectric encoder based on the gear, the absolute measuring ring photoelectric encoder is small in size and simple to install and adjust.

Drawings

FIG. 1 is a schematic structural diagram of an absolute type measuring ring photoelectric encoder based on a digital potentiometer according to the present invention;

FIG. 2 is a schematic diagram of a processing circuit in the absolute type measuring coil photoelectric encoder based on the digital potentiometer according to the present invention;

FIG. 3 is a circuit diagram of a compensation calibration circuit in the absolute type measuring coil photoelectric encoder based on the digital potentiometer according to the present invention;

FIG. 4 is a flow chart of the application of the absolute type measuring ring photoelectric encoder based on the digital potentiometer.

Detailed Description