Gyroscope accelerometer outer ring angle measuring device based on double-reading-head photoelectric encoder

Abstract

The invention discloses a gyro accelerometer outer ring angle measuring device based on double reading head photoelectric coding. The angle measuring device comprises a photoelectric encoder and a signal processing and output circuit. When the outer ring of the gyro accelerometer rotates, the double reading heads of the photoelectric encoder output sine and cosine signals, amplification, comparison shaping, analog-to-digital conversion and level conversion are completed by the signal processing and output circuit, and data processing such as direction and angle high-order value counting, subdivision and angle value average calculation is completed in the FPGA. The signal processing and output circuit completes timing output according to an external timing signal, and measurement of the outer ring angle and the rotating speed of the gyro accelerometer is achieved. According to the invention, the problem that the precision of a photoelectric encoder with a single reading head is not enough is solved, a rotary transformer type sensor angle measuring device traditionally used by the outer ring of the gyro accelerometer can be replaced in situ, the angle measuring resolution of the outer ring of the gyro accelerometer is greatly improved, and the device has the characteristics of high resolution and high precision.

Description

Technical Field

[0001] This invention belongs to the field of inertial technology and photoelectric encoders, and particularly relates to an outer ring angle measuring device for a gyroscope accelerometer based on a dual-reading-head photoelectric encoder. Background Technology

[0002] The pendulum integrating gyro accelerometer (Gyro accelerometer for short) is currently recognized worldwide as the most accurate accelerometer for engineering applications. Installed on a stable platform in inertial space, it measures the apparent acceleration of a carrier. As an irreplaceable core inertial instrument in an inertial navigation system, the performance and accuracy of the gyro accelerometer directly affect the navigation positioning accuracy of the carrier. Therefore, improving the measurement accuracy of the gyro accelerometer is of great significance to improving the navigation accuracy of the carrier.

[0003] The rotational speed of the outer ring of a gyro accelerometer is linearly proportional to the apparent acceleration. The outer ring can be considered a general shaft system. An angle sensor measures the shaft rotation angle (angular position), and the rotational speed is obtained by dividing the angle rotated over a certain time by the time. The outer ring of a gyro accelerometer typically uses a variable magnetoresistive (VMR) sensor as its angle sensor. This sensor outputs sine and cosine signals during the precession of the gyro accelerometer, along with a system reference excitation signal. The VMR signals are converted into pulses with positive and negative polarities and counted; the number of pulses per unit time characterizes the magnitude of the apparent acceleration. Because the machining accuracy of VMR sensors and the accuracy of the shaft-angle converter have reached their limits, improving the measurement accuracy of gyro accelerometers is extremely difficult. Furthermore, as a magnetically sensitive element, the VMR sensor is easily interfered with in complex electromagnetic environments such as vibration tables. These factors limit the continuous improvement of the accuracy of gyro accelerometers. The patent "A Gyroscope Accelerometer Output System Based on Photoelectric Encoder" (application number CN202411385818) proposes a new technical solution for replacing the variable magnetoresistive sensor with a photoelectric encoder in the outer ring output device of a gyroscope accelerometer. This breaks through the output accuracy limitations of the original variable magnetoresistive sensor and improves the accuracy of the pendulum gyroscope accelerometer. However, the accuracy of photoelectric encoders is affected by factors such as installation errors, engraving errors, and electronic subdivision errors. In particular, the first-order error caused by installation eccentricity accounts for the largest proportion. The technical solution using a single reading head is difficult to compensate for these errors, resulting in limited accuracy capability of a single reading head photoelectric encoder. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a gyro accelerometer outer ring angle measurement device based on a dual-reading-head photoelectric encoder. By optimizing a single reading head into a dual-reading-head solution and using an equal division averaging method to achieve error compensation, this invention solves the problem of limited accuracy in measuring the outer ring rotation angle of a gyro accelerometer with a single reading head. It replaces the system that uses a variable magnetoresistive sensor as the output device, and ultimately achieves the goal of improving the accuracy of the gyro accelerometer.

[0005] The technical solution of this invention is:

[0006] A gyro accelerometer outer ring angle measuring device based on a dual-readhead photoelectric encoder, comprising:

[0007] The dual-reading head photoelectric encoder is connected to the outer ring of the gyro accelerometer. It rotates with the outer ring shaft of the gyro accelerometer and converts the mechanical displacement of the outer ring shaft into two pairs of differential sine signals, two pairs of differential cosine signals, and two zero-position signals through photoelectric conversion, which are then output to the signal processing and output circuit.

[0008] The signal processing and output circuit converts two pairs of differential sine signals and two pairs of differential cosine signals into two sine signals and two cosine signals. It determines the direction of the sine and cosine signals by phase to form a direction signal. It converts any single sine signal into a positive pulse signal and any single cosine signal into a negative pulse signal. Then, it outputs the positive pulse signal, negative pulse signal, and direction signal. It calculates the outer ring angle of the gyro accelerometer and outputs it under the drive of a timing signal.

[0009] Preferably, the dual-readhead photoelectric encoder includes two readheads, a code disk, and a code disk base;

[0010] The encoder base is connected to the outer ring of the gyro accelerometer and rotates with the outer ring of the gyro accelerometer.

[0011] The code disk is bonded to the code disk base;

[0012] Two reading heads are mounted radially symmetrically on the housing of the gyro accelerometer;

[0013] Each reading head includes a light-emitting plate, a light-indicating base, a static light grating, and a receiving plate; the light-emitting plate is mounted on the light-indicating base, and three infrared solid-state light-emitting diodes corresponding to the sine, cosine, and zero positions are set on the light-emitting plate. The infrared solid-state light-emitting diodes emit light under the drive of a power supply to provide a light source;

[0014] The light base is the mounting reference for the light-emitting plate and the static grating, and it is fixed to the housing of the gyroscope accelerometer;

[0015] The static grating is mounted on the light-emitting base and forms moiré fringes with the code disk under the condition that the light-emitting plate provides the light source; the receiving plate has two photoelectric receiving elements of the reading head that are radially symmetrically distributed. They work under the power supply and the light source to form the differential sine signal, differential cosine signal and zero position signal of the two reading heads.

[0016] Preferably, the signal processing and output circuit includes:

[0017] The amplifier circuit is used to amplify the differential sine and differential cosine signals from the two reading heads, forming two sine signals and two cosine signals, and then outputting them to the analog-to-digital converter circuit.

[0018] The analog-to-digital converter circuit is used to convert two sine signals and two cosine signals into digital quantities, which are then output to the FPGA circuit.

[0019] The comparison shaping circuit is used to shape two sine signals, two cosine signals, and two zero-position signals, and converts the sine and cosine signals into square wave signals.

[0020] Level conversion circuit, used to convert the current square wave signal into a square wave signal adapted to the FPGA circuit;

[0021] The FPGA circuit processes the square wave signal after the level conversion circuit, identifies the rotation direction of the outer ring of the gyroscope accelerometer, and generates a direction signal; it controls and reads the output signal of the analog-to-digital conversion circuit to obtain two sine signals and two cosine signals; it calculates the angle value of the outer ring of the gyroscope accelerometer and outputs it to the serial port circuit.

[0022] The serial port circuit is used to send the outer ring angle value of the gyroscope accelerometer to the outside world.

[0023] Preferably, it also includes a wiring harness for connecting the receiver board to the signal processing and output circuitry.

[0024] Preferably, the FPGA circuit includes an ADC acquisition unit, a drive control unit, a direction division unit, an angle high-bit value counting unit, a subdivision unit, an angle value averaging calculation unit, and a serial port unit.

[0025] The ADC acquisition unit, under the action of a timing signal, controls the ADC chip of the chip select analog-to-digital converter circuit through the IO port, starts the sampling and conversion work of the ADC chip, and reads the digital values ​​of 2 sine and 2 cosine signals through the SPI interface.

[0026] The drive control unit controls the signal transmission direction of the level conversion circuit through the I / O port;

[0027] The direction-determining unit determines the direction of the four square wave signals by phase analysis, generates direction signals, and converts the four square wave signals into positive and negative pulse signals, and outputs the direction signals and positive and negative pulse signals to the outside.

[0028] The angle high-order value counting unit increments / decrements the angle value at the rising edge of the two square wave signals converted from two sine signals. The result of the increment / decrement is the angle high-order value, and the increment / decrement step size is 360° / 2. nThe falling edge of the two zero-position square wave signals is identified, and the high and low angle values ​​are cleared to zero at the falling edge of the two zero-position square wave signals; n is the code disk scale resolution.

[0029] The subdivision unit performs m-bit subdivision of the period of the two sinusoidal signals. At this point, the outer ring angular resolution of the gyro accelerometer is 360° / 2. (m+n) The amplitudes of two sine and two cosine signals are used to obtain the subdivision angle values ​​within the two sine cycles, i.e., the low-order angle values.

[0030] The angle value averaging calculation unit adds the high-order angle value and the low-order angle value of each reading head to obtain the angle value measured by the corresponding reading head. The angle values ​​measured by the two reading heads are added together and divided by 2 to obtain the outer ring angle value of the gyro accelerometer, and then sent to the serial port unit.

[0031] The serial port unit transmits the angle value to the serial port circuit through the IO port after the outer ring angle value of the gyroscope accelerometer is updated in each timing signal cycle.

[0032] Preferably, when the direction signal of the sub-direction unit is positive, the angle high-order value counting unit accumulates the angle value at the rising edge of the two square wave signals converted from the two sine signals; when the direction signal of the sub-direction unit is negative, the angle high-order value counting unit decrements the angle value at the rising edge of the two square wave signals converted from the two sine signals.

[0033] Preferably, the serial port circuit uses JS2682 to output the outer ring angle value of the gyroscope accelerometer in simplex mode.

[0034] Preferably, the FPGA circuit uses an external clock timing signal as a reference.

[0035] Preferably, the gyroscope accelerometer is a pendulum gyroscope accelerometer.

[0036] Preferably, the photoelectric encoder is an incremental photoelectric encoder or an absolute photoelectric encoder.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] This invention employs a dual-reading-head radially symmetrical mounting technique, replacing the existing single-reading-head approach. It utilizes the data from the two reading heads to perform equal division and averaging, with the average value serving as the final output value of the gyro accelerometer's outer ring angle measurement device. This reduces the impact on the signal caused by grating disk misalignment and shaft wobble, resolving the installation error (eccentricity error) that cannot be eliminated by a single reading head, and also minimizing the original engraving error. Compared with existing technologies, it significantly improves the angular measurement accuracy of the outer ring of the gyro accelerometer by more than 3 times, and reduces the time difference of constant number timing for multiple consecutive revolutions by more than 3 times.

[0039] This invention uses projection and reflection to acquire optical signals, which is beneficial for reducing the diameter of the code disk and increasing the contact area between the base supporting the code disk and the code disk. This not only solves the problem of strong constraints due to the small structural space of the gyroscope accelerometer, but also increases the structural strength of the code disk. Compared with the code disk of the existing technology, it can better resist mechanical stresses such as vibration and impact.

[0040] This invention designs a timed angle measurement function, which latches and outputs the angle value at the falling edge of the external precision frequency standard signal, thus obtaining the angle at precise time intervals. Based on the existing technology that only outputs pulses, this invention adds a timed angle measurement function and outputs the original sine and cosine signals, providing richer data interfaces to meet more application scenarios. Attached Figure Description

[0041] Figure 1 This is a general functional block diagram of an outer ring angle measuring device for a gyroscope accelerometer based on a dual-reading-head photoelectric encoder, according to an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the amplifier circuit in an embodiment of the present invention;

[0043] Figure 3 This is a diagram illustrating the principle of comparison shaping in an embodiment of the present invention;

[0044] Figure 4 This is a block diagram of the level conversion circuit in an embodiment of the present invention. Detailed Implementation

[0045] This invention proposes a gyroscope accelerometer outer ring angle measuring device based on a dual-read-head photoelectric encoder, comprising: a dual-read-head photoelectric encoder, a signal processing and output circuit, and a wiring harness.

[0046] The dual-readhead photoelectric encoder is connected to the outer ring shaft system of the gyro accelerometer. As the outer ring shaft of the gyro accelerometer rotates, the mechanical displacement of the outer ring shaft is converted into two pairs of differential sine signals, two pairs of differential cosine signals, and two zero-position signals through the photoelectric conversion of the dual readheads. These signals are then output to the signal processing and output circuit via a wiring harness. The phase difference between the sine and cosine signals represents the precession direction of the outer ring, the frequency of the sine and cosine signals represents the precession speed of the outer ring, and the zero-position signal indicates that the outer ring has passed the zero mark.

[0047] The signal processing and output circuit converts two pairs of differential sine signals and two pairs of differential cosine signals into two sine signals and two cosine signals respectively, performs analog-to-digital conversion, and synchronously outputs the sine and cosine signals from the two reading heads. The FPGA circuit performs inverse trigonometric function calculations and subdivision processing on the digital values ​​of the sine and cosine signals to obtain the angle within one electrical cycle. Simultaneously, the signal processing and output circuit compares and shapes the two sine signals, two cosine signals, and the zero-position signal from any reading head, and transmits this data to the FPGA circuit via a level conversion circuit. The FPGA circuit then determines the direction of the sine and cosine signals from any reading head based on their phase. The system then generates a direction signal by converting the sine and cosine signals from any reading head into positive and negative pulse signals. These positive and negative pulse signals are then frequency-divided to form a pulse signal, which is then output as a pulse and direction signal. Simultaneously, the FPGA circuit performs electrical cycle angle accumulation direction processing on the sine or cosine signal from any reading head to obtain the subdivided angle accumulation direction, thereby obtaining the angle value of that reading head. The FPGA circuit then performs an arithmetic average of the angle values ​​from the two reading heads to obtain the real-time angle value of the outer ring of the gyro accelerometer. By obtaining the real-time angle value through timed serial communication, the rotational speed of the outer ring of the gyro accelerometer can be calculated.

[0048] The wiring harness is used for transmitting the sine, cosine, zero-position signals and 5V power supply output from the dual-read head photoelectric encoder, and sends the sine, cosine, and zero-position signals to the processing and output circuit.

[0049] Furthermore, the dual-readhead photoelectric encoder includes a #1 reading head, a #2 reading head, and a code disk. These two reading heads are radially symmetrically mounted on the gyro accelerometer housing. The code disk rotates with the outer ring shaft of the gyro accelerometer. The #1 reading head converts the mechanical displacement into two differential signals—a differential sine signal and a differential cosine signal—through photoelectric conversion. Similarly, the #2 reading head converts the mechanical displacement into two differential signals—a differential sine signal and a differential cosine signal—through photoelectric conversion. The apparent acceleration measured by the pendulum gyro accelerometer is reflected in the four pairs of differential sine and cosine signals output by the dual-readhead photoelectric encoder, which are then calculated. In addition, the dual-readhead photoelectric encoder also outputs two zero-position signals. These four pairs of differential sine and cosine signals are transmitted via a wiring harness to the amplification circuit of the signal processing and output circuit. These two zero-position signals are also transmitted via a wiring harness to the comparison and shaping circuit of the signal processing and output circuit.

[0050] Furthermore, the signal processing and output circuit includes an amplifier circuit, an analog-to-digital converter circuit, a comparison and shaping circuit, a level conversion circuit, an FPGA circuit, and a serial port circuit;

[0051] The amplifier circuit receives four pairs of differential sine and cosine signals from the wiring harness, which are connected to the input terminals of four differential amplifiers. After differential amplification, two sine and two cosine signals are generated and output directly, while simultaneously being transmitted to the comparator and shaping circuit.

[0052] The comparison shaping circuit compares the two sine, two cosine, and two zero-position signals after differential amplification with the center level GND. After comparison shaping, they are converted into six square wave signals for easier processing by subsequent circuits.

[0053] The level conversion circuit converts the six 5V square wave signals from the comparator and shaping circuit into six 3.3V level signals, which are then transmitted to the FPGA circuit. The FPGA circuit controls the signal transmission direction of the level conversion circuit through OE and DIR.

[0054] The analog-to-digital conversion circuit uses a 24-bit high-precision four-channel ADC chip to perform analog-to-digital conversion on the two sine and two cosine signals after differential amplification, converting them into digital quantities and transmitting them to the FPGA circuit.

[0055] The serial port circuit uses an RS485 serial port chip to transmit the angle values ​​of the gyroscope accelerometer to the outside world.

[0056] The FPGA circuit includes an ADC acquisition unit, a drive control unit, a direction division unit, an angle high-order value counting unit, a subdivision unit, an angle value averaging unit, and a serial port unit. The ADC acquisition unit, under the action of a timing signal xHz, controls the ADC chip in the analog-to-digital converter circuit via the I / O port, initiating the ADC chip's sampling and conversion operation. It reads the digital values ​​of two sine and two cosine signals via the SPI interface at a fixed period of 1 / x seconds to obtain the amplitude of the two sine and two cosine signals. The drive control unit controls the signal transmission direction of the level conversion circuit via I / O ports OE and DIR. The direction division unit determines the direction of four square wave signals by phase analysis, forming direction signals, and simultaneously converts the four square wave signals into positive and negative pulse signals, outputting the direction signals and the positive and negative pulse signals. The angle high-order value counting unit accumulates / subtracts the angle value at the rising edge of the two square wave signals (converted from sine signals), with the accumulation / subtraction value being 360° / 2. n The system also performs falling edge identification on the two zero-position square wave signals. At the falling edge of each of the two zero-position square wave signals, both the high and low angle values ​​are cleared to zero. In the subdivision unit, to achieve higher resolution for the outer ring angle measurement of the gyro accelerometer, the two sine wave periods are subdivided into m-bit segments. This results in an outer ring angle measurement resolution of 360° / 2. (m+n)Specifically, the system uses two sine and two cosine signals to obtain the trigonometric limits by looking up a table and then calculates the subdivision angle using an inverse trigonometric function. This subdivision angle is then added to the initial value of the trigonometric limits to obtain the subdivision angle value within the two sine cycles, i.e., the low-order angle value. The angle value averaging unit adds the high-order angle value to the low-order angle value to obtain the angle value measured by each reading head. The angle values ​​measured by the two reading heads are added together and divided by 2 to obtain the outer ring angle value of the gyro accelerometer, which is then output to the outside via the serial port unit. The serial port unit transmits the angle value to the serial port circuit via the IO port after the outer ring angle value of the gyro accelerometer is updated in each timing signal cycle.

[0057] Example:

[0058] This embodiment presents a gyro accelerometer outer ring angle measurement device based on a dual-reading-head photoelectric encoder, such as... Figure 1 As shown, it includes: a dual-reading head photoelectric encoder 1, a signal processing and output circuit 19, and a wiring harness 7.

[0059] The dual-readhead photoelectric encoder 1 is connected to the outer ring shaft system 10 of the gyro accelerometer. As the outer ring shaft of the gyro accelerometer rotates, the mechanical displacement of the outer ring shaft is converted into two pairs of differential sine signals, two pairs of differential cosine signals, and two zero-position signals through the photoelectric conversion of the dual readheads. These signals are then output to the signal processing and output circuit 19 through the wiring harness 7. The phase difference of the sine and cosine signals represents the precession direction of the outer ring, the frequency of the sine and cosine signals represents the precession speed of the outer ring, and the zero-position signal indicates that the outer ring has passed the zero mark. The signal processing and output circuit 19 converts two pairs of differential sine signals and two pairs of differential cosine signals into two sine signals and two cosine signals respectively, performs analog-to-digital conversion, and synchronously outputs the sine and cosine signals of the two reading heads. The FPGA circuit performs inverse trigonometric function calculation and subdivision processing on the digital quantities of the sine and cosine signals to obtain the angle within one electrical cycle. At the same time, the signal processing and output circuit 19 compares and shapes the two sine signals, the two cosine signals, and the zero-position signal of any reading head, and transmits them to the FPGA circuit through the level conversion circuit. The FPGA circuit determines the direction of the sine and cosine signals of any reading head through phase conversion. After judgment, a direction signal is generated. The sine and cosine signals of any reading head are converted into positive and negative pulse signals. The positive and negative pulse signals are then divided to form a pulse signal, which is output as a pulse and direction signal. At the same time, the FPGA circuit performs electrical periodic angle accumulation direction processing on the sine or cosine signal of any reading head to obtain the subdivided angle accumulation direction, thereby obtaining the angle value of that reading head. The FPGA circuit performs an arithmetic average of the angle values ​​of the two reading heads to obtain the real-time angle value of the outer ring of the gyro accelerometer. The rotational speed of the outer ring of the gyro accelerometer can be calculated by obtaining the real-time angle value through timed serial communication.

[0060] The dual-readhead photoelectric encoder 1 includes a #1 readhead, a #2 readhead, a code disk 3, a code disk base 4, and a wiring harness 7. The #1 readhead includes a light-emitting plate 11, a light-indicating base 12, a static grating 2, and a receiving plate 6; the #2 readhead includes a light-emitting plate 9, a light-indicating base 8, a static grating 5, and a receiving plate 6. Photoelectric receiving elements for the #1 and #2 readheads are symmetrically distributed on the receiving plate 6. Specifically, as shown... Figure 1 As shown:

[0061] Both light-emitting panels 9 and 11 use infrared solid-state light-emitting diodes (SSDs) OP224 as their light source. Each reading head has one OP224 for sine, cosine, and zero positions. The OP224 SSDs operate under a 5V power supply.

[0062] Static grating 2, static grating 5, and code disk 3 are all made of K9 optical glass. Specifically, code disk 3 has 2 scribe lines. n .

[0063] The code disk 3 is mounted on the code disk base 4 by adhesive bonding.

[0064] The photoelectric receiving element of receiver board 6 uses phototransistors ND0603B-1000. One ND0603B-1000 phototransistor is used for each of the differential sine wave signal, differential cosine wave signal, and zero-position signal of reading head #1, and one ND0603B-1000 phototransistor is used for each of the differential sine wave signal, differential cosine wave signal, and zero-position signal of reading head #2. Therefore, receiver board 6 has a total of 10 ND0603B-1000 phototransistors. The ND0603B-1000 phototransistors operate under the influence of a 5V power supply and light.

[0065] The dual-readhead photoelectric encoder 1 rotates along with the outer ring shaft of the gyro accelerometer. Reading head #1 converts the mechanical displacement into two differential signals via photoelectric conversion: differential sine signals sin1+ and sin1-, and differential cosine signals cos1+ and cos1-. Similarly, reading head #2 converts the mechanical displacement into two differential signals via photoelectric conversion: differential sine signals sin2+ and sin2-, and differential cosine signals cos2+ and cos2-. The apparent acceleration measured by the pendulum gyro accelerometer is reflected in the four pairs of differential sine and cosine signals output by the dual-readhead photoelectric encoder 1, which are then calculated. Additionally, the dual-readhead photoelectric encoder 1 outputs two zero-position signals, Z1 and Z2. These four pairs of differential sine and cosine signals are transmitted via wiring harness 7 to the amplification circuit 13 of the signal processing and output circuit 19. These two zero-position signals are transmitted through the wiring harness 7 to the comparison and shaping circuit 17 of the signal processing and output circuit 19.

[0066] Amplifier circuit 13 receives four pairs of differential sine and cosine signals (sin1+, sin1-, cos1+, cos1-, sin2+, sin2-, cos2+, cos2-) from wire harness 7, and is connected to the input terminals of four differential amplifiers AD620BN, respectively. Figure 2 sin1+ and sin1- are a pair of differential signals, which are amplified and converted into the sin1 signal; cos1+ and cos1- are a pair of differential signals, which are amplified and converted into the cos1 signal; sin2+ and sin2- are a pair of differential signals, which are amplified and converted into the sin2 signal; cos2+ and cos2- are a pair of differential signals, which are amplified and converted into the cos2 signal. sin1, cos1, sin2, and cos2 are either directly output externally or simultaneously transmitted to the comparator-shaping circuit 17.

[0067] Compare shaping circuit 17, see Figure 3 The amplified sin1, cos1, sin2, cos2 and the two zero-position signals Z1 and Z2 are compared with the center level GND. After passing through the comparator LM2902M, they are shaped into square wave signals, namely Fsin1, Fcos1, Fsin2, Fcos2, FZ1, and FZ2.

[0068] Level conversion circuit 18, see Figure 4 The six 5V square wave signals from the comparison shaping circuit 17 are converted into six 3.3V level signals and transmitted to the FPGA circuit 15. The FPGA circuit 15 controls the signal transmission direction of the level conversion circuit 18 through OE and DIR.

[0069] The analog-to-digital converter circuit 14 uses a 24-bit AD7124 chip to perform analog-to-digital conversion on the amplified sin1, cos1, sin2, and cos2 signals, converting them into digital quantities and transmitting them to the FPGA circuit 15.

[0070] Serial port circuit 16 uses the RS485 serial port chip JS2682 to transmit the angle value of the gyroscope accelerometer to the outside.

[0071] FPGA circuit 15 includes an ADC acquisition unit, a drive control unit, a direction division unit, an angle high-order value counting unit, a subdivision unit, an angle value averaging calculation unit, and a serial port unit. The ADC acquisition unit, under the action of a timing signal xHz, controls the AD7910 chip in the chip select analog-to-digital converter circuit 14 via the IO port, initiating the sampling and conversion operation of the AD7124 chip. At a fixed period of 1 / x seconds, it reads the digital values ​​of sin1, cos1, sin2, and cos2 through the SPI interface, denoted as Lsin1, Lcos1, Lsin2, and Lcos2, thus obtaining the digital values ​​of the sin1, cos1, sin2, and cos2 signals. The drive control unit controls the signal transmission of the level conversion circuit 18 through the IO ports OE and DIR. The direction input unit uses the square wave signals Fsin1, Fcos1, Fsin2, and Fcos2 to determine the direction by analyzing their phase, forming a direction signal DIR-pulse. Simultaneously, it converts the square wave signals Fsin1, Fcos1, Fsin2, and Fcos2 into positive and negative pulse signals, and outputs the direction signal DIR-pulse and the positive and negative pulse signals. The angle high-order value counting unit uses registers Reg1 and Reg2 to increment / decrement the angle value at the rising edges of Fsin1 and Fsin2, with the increment / decrement being 360° / 2. n The falling edges of the zero-position square wave signals FZ1 and FZ2 are identified. At the falling edge of FZ1, registers Reg1 and Reg_s1 are both cleared to zero; at the falling edge of FZ2, registers Reg2 and Reg_s2 are both cleared to zero. For the subdivision unit, to achieve higher resolution for the outer ring angle measurement of the gyro accelerometer, the sin1 and sin2 periods are subdivided by m bits, thus achieving an outer ring angle measurement resolution of 360° / 2. (m+n) Specifically, by using the inverse trigonometric functions of Lsin1 and Lcos1, and Lsin2 and Lcos2, and then obtaining the subdivision angles through a lookup table, these subdivision angles are added to the initial values ​​of the octaves to obtain the subdivision angle values ​​Reg_s1 and Reg_s2 within the sin1 and sin2 periods. The angle value averaging unit adds register Reg1 and Reg_s1 to obtain the measured angle value REG1 of the 1# reading head, adds register Reg2 and Reg_s2 to obtain the measured angle value REG2 of the 2# reading head, and adds register REG1 and REG2 and divides by 2 to obtain the outer ring angle value REG of the gyroscope accelerometer, and outputs the angle value to the outside through the serial port unit. The serial port unit transmits the angle value REG to the serial port circuit 16 through the IO port after the outer ring angle value REG of the gyroscope accelerometer is updated in each timing signal period.

[0072] Specifically, this example demonstrates how to determine the direction of square wave signals Fsin1 and Fcos1 through phase, and convert the square wave signal Fsin1 into positive and negative pulses:

[0073] When the phase difference between Fsin1 and Fcos1 is 90°, it indicates that the gyro accelerometer is precessing in the positive direction, and the direction signal is positive. The rising edge of Fsin1 is recorded as the rising edge of the positive pulse, and the falling edge of Fsin1 is recorded as the falling edge of the positive pulse. When the phase difference between Fsin1 and Fcos1 is 270°, it indicates that the gyro accelerometer is precessing in the negative direction, and the direction signal is negative. The rising edge of Fsin1 is recorded as the rising edge of the negative pulse, and the falling edge of Fsin1 is recorded as the falling edge of the negative pulse.

[0074] Driven by clock and direction signals, the rising edge, falling edge, and holding level of a positive pulse are combined to obtain a positive pulse (i.e., "pulse+"), and the rising edge, falling edge, and holding level of a negative pulse are combined to obtain a negative pulse (i.e., "pulse-").

[0075] Driven by the rising edge of the clock, a 2-bit register Areg records the high and low level states of the square wave signal Fsin1 (by default, high level is 1 and low level is 0 in digital circuits). The low-order bit of Areg records the Fsin1 level at the current rising edge of the clock, and the high-order bit of Areg records the Fsin1 level at the previous rising edge of the clock. Similarly, a 2-bit register Breg records the high and low level states of the square wave signal Fcos1. The low-order bit of Breg records the Fcos1 level at the current rising edge of the clock, and the high-order bit of Breg records the Fcos1 level at the previous rising edge of the clock. In this way, the square wave signals Fsin1 and Fcos1 are converted from analog (high level, low level) to digital (0, 1) with the clock as the time axis.

[0076] A 1-bit register DIR-pulse records the direction signal, and a 2-bit register Areg1 synchronously records Areg. Driven by the rising edge of the clock, when Areg equals 2'b01 (2'b01 represents a rising edge), if Breg equals 2'b00 (2'b00 represents a low level with a two-clock width), it indicates that the gyro accelerometer is precessing in the positive direction. DIR-pulse is set to 1 to indicate a positive direction signal, and Areg1 is set to Areg to indicate that Areg1 records the rising edge of a positive pulse. If Breg equals 2'b11 (2'b11 represents a high level with a two-clock width), it indicates that the gyro accelerometer is precessing in the negative direction. DIR-pulse is set to 0 to indicate a negative direction signal, and Areg1 records the rising edge of a positive pulse. Assigning a value of 1 to Areg indicates that Areg1 records the rising edge of a negative pulse. When Areg equals 2'b10 (2'b10 represents the falling edge), if Breg equals 2'b00, it indicates negative precession of the gyro accelerometer, DIR-pulse is assigned a value of 0 indicating a negative direction signal, and Areg1 is assigned a value of Areg indicating that Areg1 records the falling edge of a negative pulse. If Breg equals 2'b11, it indicates positive precession of the gyro accelerometer, DIR-pulse is assigned a value of 1 indicating a positive direction signal, and Areg1 is assigned a value of Areg indicating that Areg1 records the falling edge of a positive pulse. This achieves the identification of direction, positive pulse rising edge, positive pulse falling edge, negative pulse rising edge, and negative pulse falling edge, i.e., direction separation and pulse separation.

[0077] A 1-bit register `busy_pos` is used to record positive pulses. Driven by the rising edge of the clock, when `Areg1` equals 2'b01, if `DIR-pulse` equals 1, then `busy_pos` equals 1; otherwise, `busy_pos` remains unchanged. When `Areg1` equals 2'b10, if `DIR-pulse` equals 1, then `busy_pos` equals 0; otherwise, `busy_pos` remains unchanged. When `Areg1` equals 2'b11 or 2'b00, `busy_pos` remains unchanged. This achieves the synthesis of positive pulses.

[0078] A 1-bit register, busy_neg, is used to record negative pulses. Driven by the rising edge of the clock, when Areg1 equals 2'b01, if DIR-pulse equals 0, then busy_neg equals 1; otherwise, busy_neg remains unchanged. When Areg1 equals 2'b10, if DIR-pulse equals 0, then busy_neg equals 0; otherwise, busy_neg remains unchanged. When Areg1 equals 2'b11 or 2'b00, busy_neg remains unchanged. This achieves the synthesis of negative pulses.

[0079] Furthermore, this example provides a specific implementation method for the angle high-order value counting unit:

[0080] Registers Reg1 and Reg2 are used to record the high-order bits of the angle values ​​measured by reading heads #1 and #2, respectively. When Areg equals 2'b01 (2'b01 represents the rising edge) and DIR-pulse equals 1'b1, register Reg1 is incremented by 360° / 2. n When Areg equals 2'b01 (2'b01 represents the rising edge) and DIR-pulse equals 1'b0, register Reg1 is subtracted by 360° / 2. n Similarly, when A2reg equals 2'b01 (2'b01 represents the rising edge) and DIR-pulse equals 1'b1, register Reg2 is incremented by 360° / 2. n When A2reg equals 2'b01 (2'b01 represents the rising edge) and DIR-pulse equals 1'b0, register Reg2 is subtracted by 360° / 2. n This enables the counting of the high-order (n-bit) values ​​of the outer ring angle of the gyro accelerometer.

[0081] Driven by the rising edge of the clock, a 2-bit register Z1reg records the high and low level states of the square wave signal FZ1 (the default value for high level in digital circuits is 1, and low level is 0). The low-order bit of Z1reg records the FZ1 level at the current rising edge of the clock, and the high-order bit records the FZ1 level at the previous rising edge of the clock. Similarly, a 2-bit register Z2reg records the high and low level states of the square wave signal FZ2. The low-order bit of Z2reg records the FZ2 level at the current rising edge of the clock, and the high-order bit records the FZ2 level at the previous rising edge of the clock. This converts the square wave signals FZ1 and FZ2 from analog (high level, low level) to digital (0, 1) with the clock as the time axis. When Z1reg equals 2'b10 (2'b10 represents a falling edge), registers Reg1 and REG1 are set to zero; when Z2reg equals 2'b10 (2'b10 represents a falling edge), registers Reg2 and REG2 are set to zero. This resets the measured values ​​of the two reading heads to zero.

[0082] Specifically, this example demonstrates the implementation method of the subdivision unit:

[0083] The periods of the sin1 and cos1 signals are equally divided into 8 subdivisions (equivalent to subdivision 2). 3Each trigram interval is a 45° interval, and the trigrams are designated as 0, 1, 2, 3, 4, 5, 6, and 7, with initial values ​​of 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° respectively. Within each trigram, the amplitude of Lsin1 is 1 for a positive value and 0 for a negative value, and the amplitude of Lcos1 is 1 for a positive value and 0 for a negative value. When Lsin1 is greater than Lcos1, it is recorded as 1, and the inverse trigonometric function arcctg is used to solve for it; when Lsin1 is less than Lcos1, it is recorded as 0, and the inverse trigonometric function arctg is used to solve for it. Within trigrams 0, 2, 4, and 6, the value of Lsin1 / Lcos1 ranges from 0 to 1, so the subdivision angle is arctg or arcctg, and the subdivision code is 0 to 2. m-3 Within the 1st, 3rd, 5th, and 7th octaves, the value of Lsin1 / Lcos1 ranges from 1 to 0, so the subdivision angle is (45°-arctg) or (45°-arcctg), and the subdivision code is 2. m-3 ~0. Note that the number of decimal places retained for arctg or arcctg must meet the resolution of 360° / 2. (m+n) .

[0084] Therefore, the subdivision unit of FPGA circuit 19 distinguishes the positive and negative amplitudes of Lsin1 and Lcos1, converts them into digital 1 or 0, compares the magnitudes of Lsin1 and Lcos1, converts them into digital 1 or 0, then determines which octet it is in by looking up a table, and then calculates the subdivision angle. Adding the octet start value, the subdivision angle value Reg_s1 within the sin1 period is obtained.

[0085] Table 1 shows one electrical cycle (360° / 2) n The division of the hexagrams within the hexagram.

[0086] Table 1 One electrical cycle (360° / 2) n Dividing the trigrams within )

[0087]

[0088] This invention discloses an angle measurement device for the outer ring of a gyro accelerometer based on dual-readhead photoelectric encoding. The output device includes a photoelectric encoder, signal processing, and output circuitry. When the outer ring of the gyro accelerometer rotates, the dual readheads of the photoelectric encoder output sine and cosine signals. The signal processing and output circuitry amplifies, compares, shapes, converts analog to digital, and levels. Data processing, including direction and angle high-order value counting, subdivision, and angle value averaging, is performed in an FPGA. The signal processing and output circuitry outputs signals at set times based on an external timing signal, thus measuring the angle and rotational speed of the gyro accelerometer's outer ring. This invention solves the problem of insufficient accuracy with a single-readhead photoelectric encoder and can replace the traditional resolver sensor angle measurement device used in the outer ring of a gyro accelerometer in situ, significantly improving the angle measurement resolution of the gyro accelerometer's outer ring and exhibiting high resolution and high precision.

[0089] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A gyro accelerometer outer ring angle measuring device based on a dual-reading-head photoelectric encoder, characterized in that, include: The dual-reading head photoelectric encoder is connected to the outer ring of the gyro accelerometer. It rotates with the outer ring shaft of the gyro accelerometer and converts the mechanical displacement of the outer ring shaft into two pairs of differential sine signals, two pairs of differential cosine signals, and two zero-position signals through photoelectric conversion, which are then output to the signal processing and output circuit. The signal processing and output circuit converts two pairs of differential sine signals and two pairs of differential cosine signals into two sine signals and two cosine signals. It determines the direction of the sine and cosine signals by phase to form a direction signal. It converts any single sine signal into a positive pulse signal and any single cosine signal into a negative pulse signal. Then, it outputs the positive pulse signal, negative pulse signal, and direction signal. It calculates the outer ring angle of the gyro accelerometer and outputs it under the drive of a timing signal.

2. The gyro accelerometer outer ring angle measuring device based on a dual-reading-head photoelectric encoder according to claim 1, characterized in that, The dual-readhead photoelectric encoder includes two readheads, a code disk, and a code disk base; The encoder base is connected to the outer ring of the gyro accelerometer and rotates with the outer ring of the gyro accelerometer. The code disk is bonded to the code disk base; Two reading heads are mounted radially symmetrically on the housing of the gyro accelerometer; Each reading head includes a light-emitting plate, a light-indicating base, a static light grating, and a receiving plate; the light-emitting plate is mounted on the light-indicating base, and three infrared solid-state light-emitting diodes corresponding to the sine, cosine, and zero positions are set on the light-emitting plate. The infrared solid-state light-emitting diodes emit light under the drive of a power supply to provide a light source; The light base is the mounting reference for the light-emitting plate and the static grating, and it is fixed to the housing of the gyroscope accelerometer; The static grating is mounted on the light-emitting base and forms moiré fringes with the code disk under the condition that the light-emitting plate provides the light source; the receiving plate has two photoelectric receiving elements of the reading head that are radially symmetrically distributed. They work under the power supply and the light source to form the differential sine signal, differential cosine signal and zero position signal of the two reading heads.

3. The outer ring angle measuring device for a gyro accelerometer based on a dual-reading-head photoelectric encoder according to claim 1, characterized in that, The signal processing and output circuitry includes: The amplifier circuit is used to amplify the differential sine and differential cosine signals from the two reading heads, forming two sine signals and two cosine signals, and then outputting them to the analog-to-digital converter circuit. The analog-to-digital converter circuit is used to convert two sine signals and two cosine signals into digital quantities, which are then output to the FPGA circuit. The comparison shaping circuit is used to shape two sine signals, two cosine signals, and two zero-position signals, and converts the sine and cosine signals into square wave signals. Level conversion circuit, used to convert the current square wave signal into a square wave signal adapted to the FPGA circuit; The FPGA circuit processes the square wave signal after the level conversion circuit, identifies the rotation direction of the outer ring of the gyroscope accelerometer, and generates a direction signal; it controls and reads the output signal of the analog-to-digital conversion circuit to obtain two sine signals and two cosine signals; it calculates the angle value of the outer ring of the gyroscope accelerometer and outputs it to the serial port circuit. The serial port circuit is used to send the outer ring angle value of the gyroscope accelerometer to the outside world.

4. The gyro accelerometer outer ring angle measuring device based on a dual-reading-head photoelectric encoder according to claim 3, characterized in that, It also includes wiring harnesses for connecting the receiver board to the signal processing and output circuitry.

5. The gyro accelerometer outer ring angle measuring device based on a dual-reading-head photoelectric encoder according to claim 3, characterized in that: The FPGA circuit includes an ADC acquisition unit, a drive control unit, a direction division unit, an angle high-bit value counting unit, a subdivision unit, an angle value averaging calculation unit, and a serial port unit. The ADC acquisition unit, under the action of a timing signal, controls the ADC chip of the chip select analog-to-digital converter circuit through the IO port, starts the sampling and conversion work of the ADC chip, and reads the digital values ​​of 2 sine and 2 cosine signals through the SPI interface. The drive control unit controls the signal transmission direction of the level conversion circuit through the I / O port; The direction-determining unit determines the direction of the four square wave signals by phase analysis, generates direction signals, and converts the four square wave signals into positive and negative pulse signals, and outputs the direction signals and positive and negative pulse signals to the outside. The angle high-order value counting unit increments / decrements the angle value at the rising edge of the two square wave signals converted from two sine signals. The result of the increment / decrement is the angle high-order value, and the increment / decrement step size is 360° / 2. n The falling edge of the two zero-position square wave signals is identified, and the high and low angle values ​​are cleared to zero at the falling edge of the two zero-position square wave signals; n is the code disk scale resolution. The subdivision unit performs m-bit subdivision of the period of the two sinusoidal signals. At this point, the outer ring angular resolution of the gyro accelerometer is 360° / 2. (m+n) The amplitudes of two sine and two cosine signals are used to obtain the subdivision angle values ​​within the two sine cycles, i.e., the low-order angle values. The angle value averaging calculation unit adds the high-order angle value and the low-order angle value of each reading head to obtain the angle value measured by the corresponding reading head. The angle values ​​measured by the two reading heads are added together and divided by 2 to obtain the outer ring angle value of the gyro accelerometer, and then sent to the serial port unit. The serial port unit transmits the angle value to the serial port circuit through the IO port after the outer ring angle value of the gyroscope accelerometer is updated in each timing signal cycle.

6. The gyro accelerometer outer ring angle measuring device based on a dual-reading-head photoelectric encoder according to claim 5, characterized in that: When the direction signal of the sub-direction unit is positive, the angle high-order value counting unit accumulates the angle value at the rising edge of the two square wave signals converted from the two sine signals; when the direction signal of the sub-direction unit is negative, the angle high-order value counting unit decrements the angle value at the rising edge of the two square wave signals converted from the two sine signals.

7. The outer ring angle measuring device for a gyro accelerometer based on a dual-reading-head photoelectric encoder according to claim 3, characterized in that: The serial port circuit uses JS2682 to output the outer ring angle value of the gyroscope accelerometer in simplex mode.

8. The gyro accelerometer outer ring angle measuring device based on a dual-reading-head photoelectric encoder according to claim 1, characterized in that: FPGA circuits use an external clock timing signal as a reference.

9. The gyro accelerometer outer ring angle measuring device based on a dual-reading-head photoelectric encoder according to claim 1, characterized in that: The gyroscope accelerometer is a pendulum gyroscope accelerometer.

10. The gyro accelerometer outer ring angle measuring device based on a dual-reading-head photoelectric encoder according to claim 1, characterized in that: The photoelectric encoder can be either an incremental photoelectric encoder or an absolute photoelectric encoder.

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