CN107017886B - Four-reading-head digital signal decoder of steel ring encoder - Google Patents

Abstract

The utility model provides a four reading head digital signal decoders of steel ring encoder, relates to high accuracy encoder signal processing field, has solved the problem that the structure flexibility that current decoder exists is poor, the program portability is weak, can't compatible multiple agreement, can't eliminate the angle measurement error. In the invention, a microprocessor unit reads an encoder protocol parameter from an EEPROM and writes the encoder protocol parameter into a logic processor unit, the logic processor unit selects an encoder reading head interface and a decoding mode according to the encoder protocol parameter, simultaneously acquires encoder data of an encoder reading head corresponding to the encoder reading head and decodes the encoder data, the microprocessor unit reads the decoded encoder data and performs mean value processing on the encoder data to obtain synthesized encoder data, and the microprocessor unit sends the synthesized encoder data to a servo controller and sends the encoder data and the synthesized encoder data to a liquid crystal display screen for real-time display. The invention has flexible protocol, strong program portability, high angle measurement precision and strong universality.

Description

A four-reading head digital signal decoder of a steel ring encoder

technical field

The invention relates to the technical field of high-precision encoder signal processing, in particular to a four-reading head digital signal decoder of a steel ring encoder.

Background technique

With the development of precision machinery, the requirements for the positioning accuracy of the mechanical system are getting higher and higher. The accuracy of the position positioning is not only closely related to the control algorithm, but also depends on the feedback accuracy of the position sensor. For example, in the control system of large aperture telescope (the control system includes servo controller, liquid crystal display, steel ring encoder (incremental encoder, absolute encoder and other components)), in order to improve the tracking accuracy of space targets, The position sensor usually uses a steel ring encoder with a large diameter, and the eccentricity during the mechanical installation of the steel ring encoder will cause a large reading error.

An encoder is a device that compiles and converts a signal or data into a signal form that can be used for communication, transmission and storage. The encoder converts angular displacement or linear displacement into electrical signals, the former is called a code wheel, and the latter is called a code ruler. Classification according to the working principle, the encoder is divided into incremental and absolute. The incremental encoder converts the displacement into a periodic electrical signal, and then converts the electrical signal into a count pulse, and the number of pulses represents the magnitude of the displacement. Each position of the absolute encoder corresponds to a certain digital code, so its indication is only related to the starting and ending positions of the measurement, and has nothing to do with the intermediate process of the measurement.

At present, most of the decoders that process the signal of the encoder are integrated with the servo controller, the circuit structure has poor flexibility, and the portability of the decoding program is not strong; and the existing decoders are all for a single reading head, And it is not compatible with multiple encoder protocols. This single readhead decoder cannot effectively eliminate the angle measurement error caused by mechanical installation, and it cannot solve the problem of high-precision angle measurement of large-diameter steel ring encoders.

SUMMARY OF THE INVENTION

In order to solve the problems of poor structural flexibility, weak program portability, incompatibility with multiple protocols, and inability to eliminate angle measurement errors existing in the existing decoder, the present invention provides a four-reading head digital signal decoder of a steel ring encoder, It meets the needs of high-precision position detection of steel ring encoders for large-diameter telescopes.

The technical scheme adopted by the present invention for solving the technical problem is as follows:

A four-reading head digital signal decoder of a steel ring encoder of the present invention includes:

A microprocessor unit connected to the servo controller through a UART serial port and an RS422 interface, the microprocessor unit receives the encoder protocol parameters of the servo controller;

The EEPROM connected to the microprocessor unit through the I ² C bus and the parameter storage interface, the microprocessor unit solidifies the encoder protocol parameters in the EEPROM;

A logic processor unit connected to the microprocessor unit through an address bus and a data bus, the microprocessor unit reads the encoder protocol parameters from the EEPROM and writes them into the logic processor unit;

4 incremental encoder readhead interfaces for converting the differential signal of the incremental encoder readhead to TTL signals, the logic processor unit communicates with the incremental encoder through the incremental encoder readhead interface The reading head is connected;

4 absolute encoder reading head interfaces for converting the differential signal of the absolute encoder reading head into TTL signals, the logic processor unit is connected with the absolute encoder reading head through the absolute encoder reading head interface;

The logic processor unit selects the corresponding encoder reading head interface and decoding mode according to the encoder protocol parameters, and simultaneously collects the encoder data of the corresponding encoder reading head and performs decoding processing on it. The encoder unit reads the decoded encoder data and performs averaging processing on it to obtain synthetic encoder data;

The microprocessor unit is connected with the liquid crystal display screen through the UART serial port and the RS232 interface, and the microprocessor unit sends the synthetic encoder data to the servo controller, and simultaneously sends the encoder data and the synthetic encoder data to the liquid crystal display screen. Display in real time.

Further, the logic processor unit includes an encoder protocol module and an encoder decoding module; the encoder protocol module is compatible with a variety of encoder protocols, including BissC protocol module, Endat2.2 protocol module, SSI protocol module, Incremental encoder frequency multiplication and counting modules, the number of each protocol module is 4; the encoder decoding module decodes the collected encoder data for the microprocessor unit to read.

Further, the sampling frequency of the encoder data is the same as the transmission frequency of the synthesized encoder data.

Further, the sampling frequency of the encoder data is 0.1 kHz to 2 kHz.

Further, the specific method of performing mean value processing on the decoded encoder data to obtain synthetic encoder data is as follows: first, perform synthetic data processing on the encoder data of two sets of steel ring encoder reading heads installed on opposite diameters, and obtain two The encoder data is preliminarily synthesized. At this time, the difference between the two preliminary synthesized encoder data is 90°, and the synthesized data is processed for the two preliminary synthesized encoder data with a difference of 90° to obtain the final synthesized encoder data.

Further, the specific method for synthetic data processing for the encoder data of the steel ring encoder reading head installed on the diameter is: install the steel ring encoder reading heads A and B on the diameter, assuming that the steel ring rotates counterclockwise, if If the angles of reading heads A and B satisfy b>a, then the combined angle θ=(a+b)/2; if the angles of reading heads A and B satisfy b<a, then the combined angle θ=((a+b)/ 2+180°)-360°, where a is the angle of reading head A, and b is the angle of reading head B.

Further, the specific method for synthetic data processing for two preliminary synthetic encoder data with a difference of 90° is: install the steel ring encoder reading heads C and D at 90°, assuming that the steel ring rotates counterclockwise, if the reading head If the angles of C and D satisfy d>c, then the combined angle θ=(c+d)/2; if the angles of reading heads C and D satisfy d<c, then the combined angle θ=((c+d)/2+ 180°)-360°, where c is the angle of the reading head C, and d is the angle of the reading head D.

Further, the microprocessor unit selects the C8051F120 chip; the logic processor unit selects the EP4CE22E144 chip.

Further, the RS422 interface selects the MAX3077E chip, which is used to realize the serial communication between the microprocessor unit and the servo controller; the RS232 interface selects the SP3220 chip, which is used to realize the communication between the microprocessor unit and the liquid crystal display screen. Serial communication; the EEPROM uses AT24C04 chip to store the encoder protocol parameters.

Further, the LTC1520 chip is selected for the four absolute encoder reading head interfaces; the MAX3077E chip is selected for the four incremental encoder reading head interfaces.

The beneficial effects of the present invention are:

1. The present invention realizes the decoding of the encoder data of the four reading heads of the steel ring encoder, and can process and synthesize the data through the encoder data mean value, thereby effectively reducing the reading error caused by the eccentricity during the mechanical installation of the steel ring encoder. , to improve the angle measurement accuracy of the large diameter steel ring encoder.

2. The decoder of the present invention has a relatively flexible circuit structure, is compatible with various encoder protocols, has strong decoding program portability, high angle measurement accuracy and strong versatility, and is suitable for precision tracking control systems for large-diameter telescopes.

3. In order to improve the position detection accuracy, the installation method with 4 reading heads evenly distributed is adopted, and the data of the 4 reading heads is averaged to eliminate the position detection error caused by the mechanical installation process. Therefore, the decoder of the present invention has great significance for improving the tracking accuracy of the large-aperture telescope.

Description of drawings

FIG. 1 is a structural block diagram of a four-reading head digital signal decoder of a steel ring encoder according to the present invention.

Figure 2 is a schematic diagram of the installation method of the four reading heads of the steel ring encoder.

Figure 3 is a schematic diagram of data processing when the steel ring encoder reading head is installed on the opposite diameter (the angles of the reading heads A and B satisfy b>a).

Figure 4 is a schematic diagram of data processing when the steel ring encoder reading head is installed in the opposite direction (the angles of the reading heads A and B satisfy b<a).

Figure 5 is a schematic diagram of data processing when the steel ring encoder reading head is installed at 90° (the angles of the reading heads C and D satisfy d>c).

Figure 6 is a schematic diagram of data processing when the steel ring encoder reading head is installed at 90° (the angles of the reading heads C and D satisfy d<c).

In the picture: 1-1, steel ring, 1-2, zero position of code disc, 1-3, synthetic angle position, 1-4, correct synthetic angle position, 1-5, incorrect synthetic angle position, A～D, reading head.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings.

As shown in Figure 1, a four-reading head digital signal decoder of a steel ring encoder of the present invention is mainly composed of a microprocessor unit, a peripheral interface unit, a logic processor unit, an encoder interface unit and an EEPROM (electrically erasable). programmable read-only memory). The microprocessor unit is respectively connected with the peripheral interface unit and the logic processor unit, and the logic processor unit is connected with the encoder interface unit.

The peripheral interface unit includes RS422 interface, RS232 interface and parameter storage interface. The RS422 interface is used to realize the serial communication between the microprocessor unit and the servo controller, the RS232 interface is used to realize the serial communication between the microprocessor unit and the LCD screen, and the parameter storage interface is used to realize the communication between the microprocessor unit and the EEPROM communication between.

The encoder interface unit includes 4 incremental encoder reading head interfaces (the first incremental encoder reading head interface, the second incremental encoder reading head interface, the third incremental encoder reading head interface, the Four incremental encoder read head interfaces) and 4 absolute encoder read head interfaces (the first absolute encoder read head interface, the second absolute encoder read head interface, the third absolute encoder read head interface , the fourth absolute encoder reading head interface). The incremental encoder readhead interface is used to realize the communication between the logic processor unit and the incremental encoder readhead, and is used to realize the conversion of differential signals to TTL signals. The absolute encoder readhead interface is used to realize the communication between the logic processor unit and the absolute encoder readhead, and is also used to realize the conversion of differential signals to TTL signals. The signals from both incremental encoder readheads and absolute encoder readheads are sent and received as differential signals.

There are 4 incremental encoders and 4 absolute encoders in the large aperture telescope control system. When the data of the incremental encoder needs to be collected, the 4 incremental encoder reading head interfaces correspond to the 4 incremental encoder reading heads, and the incremental encoder data is collected; when the absolute encoder data needs to be collected When reading data, the 4 absolute encoder reading head interfaces correspond to the 4 absolute encoder reading heads, and the absolute encoder data is collected. The data collection of 4 incremental encoders and the collection of 4 absolute encoder data are not carried out at the same time, while the collection of 4 incremental encoder data is carried out at the same time, and the collection of 4 absolute encoder data is also simultaneously.

The microprocessor unit is connected with the servo controller through the UART serial port and the RS422 interface, and the microprocessor unit is connected with the EEPROM (electrically erasable programmable read-only memory) through the I ² C bus and the parameter storage interface. The microprocessor unit receives the encoder protocol parameters from the servo controller through the UART serial port and the RS422 interface, and the microprocessor unit solidifies the encoder protocol parameters in the EEPROM through the I ² C bus and the parameter storage interface.

The microprocessor unit is connected to the logical processor unit through an address bus and a data bus. The microprocessor unit reads the encoder protocol parameters stored in the EEPROM through the I ² C bus and the parameter storage interface, and simultaneously writes the encoder protocol parameters into the logic processor unit through the address bus and the data bus.

The logic processor unit is connected with the 4 incremental encoder reading heads through the digital interface and the incremental encoder reading head interface. One-to-one correspondence; the logic processor unit is connected with 4 absolute encoder reading heads through the digital interface and the absolute encoder reading head interface, and the digital interface, the absolute encoder reading head interface, and the absolute encoder reading head are connected between for a one-to-one correspondence.

The logic processor unit includes an encoder protocol module and an encoder decoding module. The encoder protocol module in the logic processor unit reads the encoder protocol parameters from the microprocessor unit, the logic processor unit selects the corresponding encoder readhead interface and decoding method according to the encoder protocol parameters, and the logic processor The unit collects the encoder data of the corresponding encoder reading head at a certain sampling frequency (0.1kHz ~ 2kHz), and then decodes the collected encoder data through the encoder decoding module for the microprocessor unit to read. After each encoder data acquisition is completed, the microprocessor unit needs to be triggered to interrupt, and then the microprocessor unit is triggered to read the encoder data decoded by the encoder decoding module through the data bus, and perform average processing on these encoder data. , to obtain synthetic encoder data.

The microprocessor unit is connected with the LCD screen through the UART serial port and the RS232 interface. The microprocessor unit sends the synthetic encoder data to the servo controller through the UART serial port and the RS422 interface, and simultaneously sends the collected encoder data and synthetic encoder data to the LCD screen through the UART serial port and the RS232 interface to display the current position in real time. Test data.

A four-reading head digital signal decoder of a steel ring encoder of the present invention has the specific working process as follows: when the system is powered on, the microprocessor unit receives the encoder protocol parameters from the servo controller through the UART serial port and the RS422 interface. , the microprocessor unit solidifies the encoder protocol parameters in the EEPROM through the I ² C bus and the parameter storage interface; the microprocessor unit sends the encoder protocol parameters to the encoder protocol inside the logic processor unit through the address bus and data bus module; the logic processor unit selects the corresponding encoder reading head interface and decoding method according to the encoder protocol module register data, and the logic processor unit collects the corresponding encoder reading head at the sampling frequency of 0.1kHz ~ 2kHz. Encoder data, the specific acquisition process is: receive differential signals (±A (±A1, ±A2, ±A3, ±A4) from the incremental encoder readhead through the incremental encoder readhead interface, ±B (±B1, ±B2, ±B3, ±B4), ±Z (±Z1, ±Z2, ±Z3, ±Z4)), which are level-converted into single-ended signals that can be processed by the logic processor unit and sent to the logic processing unit The encoder decoding module in the encoder unit, or the logic processor unit sends serial clock signals (±M (±M1, ±M2, ±M3, ±M4) to the absolute encoder readhead through the absolute encoder readhead interface ), and receive the serial data signal (±S(±S1,±S2,±S3,±S4)) from the absolute encoder readhead; then the encoder data is decoded by the encoder decoding module for micro The processor unit reads; after each encoder data acquisition is completed, the microprocessor unit needs to be triggered to interrupt, and then the microprocessor unit is triggered to read the encoder decoding module register data through the data bus, and the encoder data is averaged , obtain the synthetic encoder data; the microprocessor unit sends the synthetic encoder data to the servo controller through the UART serial port and the RS422 interface, the sending frequency of the synthetic encoder data is the same as the sampling frequency of the encoder data, and the collected encoder The data and synthetic encoder data are sent to the LCD screen through the UART serial port and RS232 interface at a transmission frequency of 20Hz, and the encoder data and synthetic encoder data are displayed on the LCD screen. Both the encoder data and synthetic encoder data are displayed. It can be displayed on the LCD screen in real time through the RS232 interface.

As shown in Figure 2, the four reading heads of the steel ring encoder are installed in a 90° distribution, which can reduce the installation error as much as possible. The specific method of performing mean value processing on the decoded encoder data to obtain synthetic encoder data is as follows: first, perform synthetic data processing on the encoder data of two sets of steel ring encoder reading heads installed on opposite diameters, and obtain two preliminary synthetic codes respectively. At this time, the two preliminary synthetic encoder data differ by 90°, and the two preliminary synthetic encoder data differing by 90° are then subjected to synthetic data processing to obtain final synthetic encoder data.

The data processing method when the steel ring encoder reading heads A and B are installed in opposite diameters is as follows: As shown in Figure 3, assuming that steel ring 1-1 rotates counterclockwise, if the angles of reading heads A and B satisfy b>a, Then the composite angle θ=(a+b)/2, the correct composite angle position is located at 1-4 in the figure, 1-2 in the figure is the zero position of the code disc; as shown in Figure 4, if the angles of the reading heads A and B are Satisfy b<a, then the synthetic angle θ=((a+b)/2+180°)-360°, the correct synthetic angle position is located at 1-4 in the figure, and the incorrect synthetic angle position is at 1-5 in the figure , 1-2 in the figure is the zero position of the code disc; in Figures 3 and 4, a is the angle of the reading head A, b is the angle of the reading head B, -360° operation is to ensure that θ is within the range of 0° to 360° .

When the steel ring encoder reading heads C and D are installed at 90°, the data processing method is as follows: As shown in Figure 5, assuming steel ring 1-1 rotates counterclockwise, if the angles of reading heads C and D satisfy d>c , then the composite angle θ=(c+d)/2, the correct composite angle position is located at 1-4 in the figure, 1-2 in the figure is the zero position of the code disc; as shown in Figure 6, if the reading heads C, D If the angle satisfies d<c, then the synthetic angle θ=((c+d)/2+180°)-360°, the correct synthetic angle is located at 1-4 in the figure, and the incorrect synthetic angle is at 1-5 in the figure 1-2 in the figure is the zero position of the code disc; in Figures 5 and 6, c is the angle of the reading head C, d is the angle of the reading head D, -360° operation is to ensure that θ is in the range of 0° to 360° Inside.

In this embodiment, the MAX3077E chip is selected for the RS422 interface, which mainly implements serial communication between the microprocessor unit and the servo controller.

In this embodiment, the RS232 interface selects the SP3220 chip, which mainly realizes the serial communication between the microprocessor unit and the liquid crystal display screen.

In this embodiment, the AT24C04 chip is used as the EEPROM to store the encoder protocol parameters. When the system is powered on, the microprocessor unit reads the internal encoder protocol parameters and sends them to the internal encoder protocol of the logic processor unit. module.

In this embodiment, the microprocessor unit is an MCU, and a C8051F120 chip is selected.

In this implementation manner, the logic processor unit is an FPGA, and an EP4CE22E144 chip is selected.

In this embodiment, the encoder protocol module in the logic processor unit is compatible with multiple encoder protocols, and the encoder protocol module mainly includes BissC protocol module, Endat2.2 protocol module, SSI protocol module, incremental encoder frequency multiplication and Counting modules, the number of each protocol module is 4.

In this embodiment, the LTC1520 chip is selected for the above-mentioned four absolute encoder reading head interfaces, and its main function is to realize the conversion of differential signals to TTL signals. The signal of the absolute encoder read head is sent and received in differential form. The differential signal form of the absolute encoder read head is: ±M (±M1, ±M2, ±M3, ±M4), ±S (±S1, ± S2, ±S3, ±S4), wherein M is the serial clock signal, and S is the serial data signal.

In this embodiment, the MAX3077E chip is selected for the above-mentioned four incremental encoder reading head interfaces, whose main function is to realize the conversion from differential signals to TTL signals. The signal of the incremental encoder read head is sent and received in differential form, and the differential signal form of the incremental encoder read head is: ±A (±A1, ±A2, ±A3, ±A4), ±B (±B1 , ±B2, ±B3, ±B4), ±Z (±Z1, ±Z2, ±Z3, ±Z4).

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (7)

1. a four-reading head digital signal decoder of a steel ring encoder, is characterized in that, comprising: A microprocessor unit connected to the servo controller through a UART serial port and an RS422 interface, the microprocessor unit receives the encoder protocol parameters of the servo controller; The EEPROM connected to the microprocessor unit through the I ² C bus and the parameter storage interface, the microprocessor unit solidifies the encoder protocol parameters in the EEPROM; A logic processor unit connected to the microprocessor unit through an address bus and a data bus, the microprocessor unit reads the encoder protocol parameters from the EEPROM and writes them into the logic processor unit; 4 incremental encoder readhead interfaces for converting the differential signal of the incremental encoder readhead to TTL signals, the logic processor unit communicates with the incremental encoder through the incremental encoder readhead interface The reading head is connected; 4 absolute encoder reading head interfaces for converting the differential signal of the absolute encoder reading head into TTL signals, the logic processor unit is connected with the absolute encoder reading head through the absolute encoder reading head interface; The logic processor unit selects the corresponding encoder reading head interface and decoding mode according to the encoder protocol parameters, and simultaneously collects the encoder data of the corresponding encoder reading head and performs decoding processing on it. The encoder unit reads the decoded encoder data and performs averaging processing on it to obtain synthetic encoder data; The microprocessor unit is connected with the liquid crystal display screen through the UART serial port and the RS232 interface, and the microprocessor unit sends the synthetic encoder data to the servo controller, and simultaneously sends the encoder data and the synthetic encoder data to the liquid crystal display screen. display in real time; The specific method of performing mean value processing on the decoded encoder data to obtain synthetic encoder data is as follows: first, perform synthetic data processing on the encoder data of two sets of steel ring encoder reading heads installed on opposite diameters, and obtain two preliminary synthetic codes respectively. At this time, the two preliminary synthetic encoder data differ by 90°, and then perform synthetic data processing on the two preliminary synthetic encoder data with a difference of 90° to obtain the final synthetic encoder data; The specific method of synthetic data processing for the encoder data of the steel ring encoder reading head installed on the opposite diameter is: install the steel ring encoder reading heads A and B on the diameter, assuming that the steel ring rotates counterclockwise, if the reading heads A, B If the angle of B satisfies b>a, then the combined angle θ=(a+b)/2; if the angles of reading heads A and B satisfy b<a, then the combined angle θ=((a+b)/2+180° )-360°, where a is the angle of the reading head A, and b is the angle of the reading head B; The specific method for synthetic data processing for two preliminary synthetic encoder data with a difference of 90° is as follows: install the steel ring encoder reading heads C and D at 90°, assuming that the steel ring rotates counterclockwise, if the reading heads C and D of the steel ring encoder If the angle satisfies d>c, then the combined angle θ=(c+d)/2; if the angles of reading heads C and D satisfy d<c, then the combined angle θ=((c+d)/2+180°)- 360°, where c is the angle of readhead C and d is the angle of readhead D. 2. The four-reading head digital signal decoder of a steel ring encoder according to claim 1, wherein the logic processor unit comprises an encoder protocol module and an encoder decoding module inside; the encoder The protocol module is compatible with a variety of encoder protocols, including BissC protocol module, Endat2.2 protocol module, SSI protocol module, incremental encoder frequency multiplication and counting module, and the number of each protocol module is 4; the coding The encoder decoding module decodes the collected encoder data for reading by the microprocessor unit. 3 . The four-reading head digital signal decoder of a steel ring encoder according to claim 1 , wherein the sampling frequency of the encoder data is the same as the transmission frequency of the synthesized encoder data. 4 . 4 . The four-reading head digital signal decoder of a steel ring encoder according to claim 1 or 3 , wherein the sampling frequency of the encoder data is 0.1 kHz to 2 kHz. 5 . 5 . The four-reading head digital signal decoder of a steel ring encoder according to claim 1 , wherein the microprocessor unit selects a C8051F120 chip; the logic processor unit selects an EP4CE22E144 chip. 6 . 6. The four-reading head digital signal decoder of a steel ring encoder according to claim 1, wherein the RS422 interface selects a MAX3077E chip for realizing the communication between the microprocessor unit and the servo controller. Serial communication; the RS232 interface selects the SP3220 chip, which is used to realize the serial communication between the microprocessor unit and the liquid crystal display screen; the EEPROM selects the AT24C04 chip for storing the encoder protocol parameters. 7. the four reading head digital signal decoder of a kind of steel ring encoder according to claim 1, is characterized in that, 4 absolute encoder reading head interfaces all select LTC1520 chip; 4 incremental encoder readings The head interface adopts MAX3077E chip.

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