CN106936387A - The correcting module and its method of sine and cosine measurement signal - Google Patents

Abstract

The invention discloses a correction module of sine and cosine measurement signals and a method thereof. The amplitude adjustment unit and the orthogonalization unit are a correction method for sinusine and cosine measurement signals without any software means. The present invention can correct the three major errors of DC drift, unequal amplitude and non-orthogonalization existing in the sine-cosine measurement signal in real time, so as to provide high-quality signals for subsequent subdivision, direction discrimination and counting, so as to improve the measurement accuracy , and reduce the burden of subsequent software revisions.

Description

Modification module and method of sin-cos measurement signal

technical field

The invention is applied to measurement occasions based on orthogonal sine wave measurement signals, such as gratings and laser interferometers, and is specifically a correction module and method for sinusine and cosine measurement signals.

Background technique

Measuring tools based on orthogonal sine wave signals such as grating sensors and laser interferometers have been widely used in various measurement occasions. The common signal processing process in industry is: photoelectric signal conversion - preamplification - differential amplification - identification orientation and subdivision. Ideally, after differential amplification, two perfect orthogonal sine wave signals with zero DC drift, equal amplitude, and 90° phase difference should be obtained (refer to the dotted line in Figure 5, and the Lissajous diagram is a circle centered at the origin ellipse), so as to provide precision guarantee for subsequent subdivision, direction identification and counting. However, due to the influence of various factors, there will inevitably be a certain deviation between the actual signal and the ideal signal (see the solid line in Figure 5). If the signal is directly counted and subdivided, a large error will occur, and when the signal is used as the feedback information in the control loop, it will cause serious control errors. Therefore, it is necessary to design a special signal correction scheme to try to reduce this deviation, thereby improving the measurement accuracy.

At present, most literatures and actual measurements use software fitting methods to correct the three types of errors of DC drift, unequal amplitude, and non-orthogonalization in the sine-cosine measurement signal. In theory, it can infinitely approach the real by increasing the sampling rate. The sine wave signal, and use the method of mathematical fitting to obtain and eliminate the three types of errors, but the software correction method increases the complexity of the signal acquisition software and the processor burden, and because the signal acquisition accuracy is limited by A/D conversion Due to factors such as the number of digits and sampling rate, there is still a certain deviation between the signal used for error correction and the real signal, and it is difficult to realize real-time correction of the signal.

Contents of the invention

In order to solve the deficiencies in the above-mentioned prior art, the present invention provides a correction module and method for the sine-cosine measurement signal, in order to correct the DC drift, unequal amplitude, and non-orthogonality existing in the sine wave measurement signal in real time. Three types of errors can be minimized to provide high-quality signals for subsequent subdivision, direction identification and counting, so as to improve measurement accuracy and reduce the burden of subsequent software corrections.

The present invention solves technical problem and adopts following technical scheme:

The characteristics of a correction module of a sine and cosine measurement signal in the present invention include: a sine differential amplifying unit, a sine de-DC drift unit, a sine amplitude adjustment unit, a cosine differential amplifying unit, a cosine de-DC drift unit, a cosine amplitude adjustment unit and a sine Exchange unit;

The sinusoidal differential amplifier unit receives and processes two sinusoidal signals sin+ and sin- with a phase difference of 180° to obtain a sinusoidal differential amplification signal sin0 and provides it to the sinusoidal DC drift removal unit for processing to obtain zero DC drift A sinusoidal signal sin1; the amplitude of the zero-DC drift sinusoidal signal sin1 is adjusted by the sinusoidal amplitude adjustment unit to obtain a corrected sinusoidal signal sin2, which is provided to the orthogonalization unit;

The cosine differential amplifier unit receives and processes two cosine signals cos+ and cos- with a phase difference of 180° to obtain a cosine differential amplification signal cos0 and provides it to the cosine de-DC drift unit for processing to obtain zero DC drift cosine signal cos1; the cosine amplitude adjustment unit adjusts the amplitude of the zero DC drift cosine signal cos1 to obtain a corrected cosine signal cos2, and provides it to the orthogonalization unit;

The orthogonalization unit performs orthogonalization processing on the corrected sine signal sin2 and cosine signal cos2 to obtain sine signal sin and cosine signal cos that are strictly orthogonal, have equal amplitudes, and have zero DC drift.

The correction module of the sine and cosine measurement signal according to the present invention is also characterized in that the sine de-DC drift unit or the cosine de-DC drift unit includes: a low-pass filter and an addition circuit;

Obtain the DC drift signal in the received one-way sine differential amplification signal sin0 or one-way cosine differential amplification signal cos0 by the low-pass filter, and provide it to the adding circuit for removing the DC drift signal, thereby Get zero DC drift sine signal sin1 or zero DC drift cosine signal cos1.

The sine amplitude adjustment unit or the cosine amplitude adjustment unit includes: a first absolute value circuit, a sample and hold circuit, a differential circuit, a second absolute value circuit, a window comparator and a division circuit;

The first absolute value circuit performs absolute value processing on the zero DC drift sine signal sin1 or the zero DC drift cosine signal cos1, and the obtained result is provided to the sample and hold circuit;

The differential circuit performs differential processing on the zero DC drift sine signal sin1 or the zero DC drift cosine signal cos1 to obtain a differential signal and provide it to the second absolute value circuit; the second absolute value circuit performs differential processing on the differential signal The signal is processed by taking the absolute value, and the obtained result is provided to the window comparator for processing, and the trigger signal is obtained and sent to the sample and hold circuit;

The sample-and-hold circuit performs real-time amplitude acquisition on the processing result of the first absolute value circuit according to the received trigger signal, thereby obtaining continuously changing amplitude information and providing it to the division circuit;

The division circuit divides the zero DC drift sine signal sin1 or the zero DC drift cosine signal cos1 and the amplitude information to obtain the corrected sine signal sin2 and cosine signal cos2.

When the amplitude changes of the zero-DC-drift sine signal sin1 or the zero-DC-drift cosine signal cos1 are synchronized, the sine amplitude adjustment unit and the cosine amplitude adjustment unit can also use the resistance voltage divider method to adjust the zero-DC drift sine The amplitude of the signal sin1 or the cosine signal cos1 with zero DC drift is adjusted to obtain a sine signal sin2 and a cosine signal cos2 with equal amplitudes after correction.

A kind of correction method of sine-cosine measurement signal of the present invention is characterized in that it is carried out as follows:

Step 1. Perform differential amplification processing on two sinusoidal signals sin+ and sin- with a phase difference of 180° to obtain a sinusoidal differential amplification signal sin0; at the same time, two cosine signals cos+ and cos- with a phase difference of 180° Perform differential amplification processing to obtain a cosine differential amplification signal cos0;

Step 2, using a low-pass filter to obtain the DC drift signal in the one-way sine differential amplification signal sin0 or one-way cosine differential amplification signal cos0, and using an addition circuit to remove the one-way sine differential amplification signal sin0 or one-way cosine difference Dynamically amplify the DC drift signal in the signal cos0 to obtain a zero DC drift sine signal sin1 and a zero DC drift cosine signal cos1;

Step 3. Equal amplitude adjustment is performed on the zero DC drift sine signal sin1 and the zero DC drift cosine signal cos1 to obtain the corrected sine signal sin2 and cosine signal cos2;

Step 3.1, performing absolute value processing on the zero-DC-drift sine signal sin1 and the zero-DC-drift cosine signal cos1 respectively, to obtain a corresponding first absolute value result for amplitude acquisition;

Step 3.2: Carry out differential processing on the zero DC drift sine signal sin1 and zero DC drift cosine signal cos1 respectively, then take the absolute value, obtain the corresponding second absolute value result, and then perform window comparison to obtain the corresponding amplitude acquisition trigger Signal;

Step 3.3, according to the corresponding amplitude acquisition trigger signal, respectively perform real-time amplitude acquisition on the corresponding first absolute value results, so as to obtain corresponding continuously changing amplitude information;

Step 3.4, divide the zero-DC-drift sine signal sin1 and the zero-DC-drift cosine signal cos1 by the corresponding amplitude information respectively, so as to obtain the corrected sine signal sin2 and cosine signal cos2;

Step 4. Orthogonalize the corrected sine signal sin2 and cosine signal cos2 to obtain sine signal sin and cosine signal cos that are strictly orthogonal, have equal amplitudes, and have zero DC drift.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. Compared with the commonly used software correction method, the present invention is a correction method of sine and cosine measurement signals without any software means, and uses pure hardware circuit means to correct the DC drift and amplitude difference existing in the two-way sine and cosine measurement signals. Etc., non-orthogonalization three types of errors are corrected to overcome the weakness of the software fitting method that requires a large amount of data calculation and fitting, which greatly reduces the complexity of subsequent signal acquisition software, and can directly use a dedicated interpolation chip to correct The signal is subdivided at a high multiple to obtain a square wave signal that is easy to distinguish and count.

2. Compared with the existing hardware circuit correction scheme, the present invention can correct the three types of errors in real time, specifically embodied in: the present invention uses a low-pass filter to obtain the constantly changing DC drift in the signal in real time and corrects it through the addition circuit Elimination overcomes the defect that the DC drift in the sine-cosine measurement signal cannot be eliminated in real time in the existing method; the present invention uses the zero-crossing point of the signal after differentiation of the original signal as the acquisition signal of the amplitude information in each cycle, which can Realize the real-time acquisition of the amplitude information of the sine-cosine measurement signal, divide the original signal by the obtained amplitude information, correct the signal amplitude in real time, and obtain the sine-cosine measurement signal whose amplitude is always one, which overcomes the existing technology The defect that the real-time amplitude correction cannot be performed on the signal whose amplitude is constantly changing.

3. For two channels of sine and cosine measurement signals with non-orthogonalization errors (that is, the phase difference is not 90°), the commonly used orthogonalization method is to add them separately on the basis of adjusting the amplitudes of the two signals to be equal Subtraction, because when the amplitudes are equal, the vector diagrams of the two signals are adjacent sides of a rhombus, the sum and difference of the two signals are the two diagonals of the rhombus, and the diagonals of the rhombus must be orthogonal (see Figure 6 for the principle ), but limited by the fact that the signal amplitude cannot be detected and corrected in real time, so the existing application cannot guarantee that the two signal amplitudes are completely equal, and it is difficult to obtain a perfect orthogonal sine wave signal. The zero-crossing point of the differentiated signal is used as the trigger information of the amplitude acquisition, and the signal amplitude can be acquired and corrected in real time, thus ensuring the feasibility of the orthogonalization principle in the practical process.

Description of drawings

Fig. 1 is the overall schematic diagram of the correction module of the present invention;

Fig. 2 is a schematic diagram of the DC drift removal unit of the present invention;

Fig. 3 a is the schematic diagram of the normalization of two signal amplitudes whose amplitude changes are asynchronous in the present invention;

Fig. 3b is a schematic diagram of two signal amplitude adjustments in which amplitude changes are synchronized according to the present invention;

Fig. 4 is a schematic diagram of the signal orthogonalization unit of the present invention;

Fig. 5 is the Lissajous diagram of the actual signal to be corrected (solid line) and the ideal signal (dotted line);

Fig. 6 is a schematic diagram of the principle of orthogonalization in the present invention.

detailed description

In this embodiment, as shown in Figure 1, the sine and cosine measurement signal correction module includes: a sine differential amplifier unit, a sine de-DC drift unit, a sine amplitude adjustment unit, a cosine differential amplify unit, a cosine de-DC drift unit, a cosine amplitude Conditioning unit and Orthogonalization unit.

The sinusoidal differential amplifier unit receives two sinusoidal signals sin+ and sin- with a phase difference of 180° and processes them to obtain a sinusoidal differential amplification signal sin0 and provides it to the sinusoidal DC drift removal unit for processing to obtain a zero DC drift sinusoidal signal sin1. The amplitude of the zero-DC drift sinusoidal signal sin1 is adjusted by the sinusoidal amplitude adjustment unit to obtain the corrected sinusoidal signal sin2, which is provided to the orthogonalization unit;

The cosine differential amplifier unit receives two cosine signals cos+ and cos- with a phase difference of 180° and processes them to obtain a cosine differential amplification signal cos0 and provides it to the cosine de-DC drift unit for processing to obtain a zero-DC drift cosine signal cos1; The cosine amplitude adjustment unit adjusts the amplitude of the zero DC drift cosine signal cos1 to obtain the corrected cosine signal cos2, and provides it to the orthogonalization unit;

The orthogonalization unit performs orthogonalization processing on the corrected sinusoidal signal sin2 and cosine signal cos2 to obtain strictly orthogonal sinusoidal signal sin and cosine signal cosine with equal amplitude and zero DC drift.

In the existing hardware circuit correction schemes, most of the DC compensation methods are used to remove the DC drift in the signal, and it is impossible to obtain and compensate the constantly changing DC drift in the actual signal in real time, but the DC drift removal method proposed in the present invention can overcome this defect , to achieve real-time DC drift removal. As shown in Figure 2, the sine de-DC drift unit or the cosine de-DC drift unit includes: a low-pass filter and an addition circuit, and the low-pass filter obtains a received sine differential amplification signal sin0 or a cosine differential amplification in real time The DC drift signal in the signal cos0 obtains a signal with the opposite polarity to the DC drift in the signal, and provides it to the addition circuit for removing the DC drift, thereby obtaining a zero DC drift sine signal sin1 or a zero DC drift cosine signal cos1. Among them, the cut-off frequency of the low-pass filter can be flexibly designed according to the frequency range of the measurement signal and considering factors such as response time.

The amplitude of the actual sine-cosine measurement signal is constantly changing, so the amplitude adjustment unit circuit is required to obtain and correct the signal amplitude information in real time, which is associated with the fact that the zero-crossing point of the original signal after differentiation is exactly corresponding to the original signal amplitude point. , using the zero-crossing point of the differential signal as the trigger signal for amplitude acquisition, the instant the differential signal crosses zero triggers the acquisition of the signal amplitude, and the acquisition result is kept as the amplitude correction signal at other times, and the amplitude correction is realized by using the division circuit, which can realize the signal amplitude real-time corrections. The present invention provides a method for realizing the above idea. After the signal to be corrected is differentiated and its absolute value is taken, a narrow pulse is generated using a window comparator to trigger a sample-and-hold circuit to collect the current signal, that is, the signal amplitude. After the narrow pulse passes, hold the The sampling result is divided by the signal to be corrected and the amplitude information by a division circuit to realize normalization of the amplitude. This method can realize real-time correction of the signal amplitude.

As shown in Figure 3a, the sine amplitude adjustment unit or the cosine amplitude adjustment unit includes: a first absolute value circuit, a sample and hold circuit, a differential circuit, a second absolute value circuit, a window comparator and a division circuit;

The first absolute value circuit performs absolute value processing on the zero DC drift sine signal sin1 or the zero DC drift cosine signal cos1, and the obtained result is provided to the sample and hold circuit;

The differential circuit performs differential processing on the zero DC drift sine signal sin1 or the zero DC drift cosine signal cos1 to obtain a differential signal and provide it to the second absolute value circuit; the second absolute value circuit performs absolute value processing on the differential signal, and the obtained result provides Process the window comparator, get the trigger signal and send it to the sample and hold circuit;

The sample-and-hold circuit performs real-time amplitude acquisition on the processing result of the first absolute value circuit according to the received trigger signal, thereby obtaining continuously changing amplitude information and providing it to the division circuit;

The division circuit divides the zero DC drift sine signal sin1 or the zero DC drift cosine signal cos1 and the amplitude information to obtain the sine signal sin2 and the cosine signal cos2 with the same amplitude after correction.

In addition, when the amplitude changes of the zero-DC-drift sine signal sin1 or the zero-DC-drift cosine signal cos1 are synchronized, the sine amplitude adjustment unit and the cosine amplitude adjustment unit can also use the resistance voltage divider method (see Figure 3b) to adjust the zero-DC drift The amplitude of the sine signal sin1 or the zero DC drift cosine signal cos1 is adjusted to obtain a sine signal sin2 and a cosine signal cos2 with equal amplitudes.

As shown in Figure 6, when the amplitudes are equal, the vector diagrams of the two sine and cosine measurement signals are adjacent sides of a rhombus, and the sum and difference of the two signals are the two diagonals of the rhombus, and the diagonals of the rhombus must be Orthogonal, so the amplitudes of the two signals can be adjusted to be equal to each other, and then they can be added and subtracted to correct the non-orthogonalization error of the signal. On the basis of the aforementioned sine amplitude adjustment unit and cosine amplitude adjustment unit adjusting the amplitudes of the two signals to be equal in real time, the sine signal sin2 and the cosine signal cos2 are respectively added and subtracted to obtain two strictly orthogonal new signals sin and cos (see Figure 4).

The two new signals sin and cos obtained through the above processing are strictly orthogonal, have equal amplitudes, and have zero DC drift. The Lissajous figure is a perfect circle with the center at the origin, which can be directly used for subsequent subdivision and counting and distinguish direction.

Claims (5)

1. A correction module of a sine and cosine measurement signal, characterized in comprising: a sine differential amplifier unit, a sine differential amplifier unit, a sine amplitude adjustment unit, a cosine differential amplifier unit, a cosine differential amplifier unit, a cosine amplitude adjustment unit and Orthogonalization unit; The sinusoidal differential amplifier unit receives and processes two sinusoidal signals sin+ and sin- with a phase difference of 180° to obtain a sinusoidal differential amplification signal sin0 and provides it to the sinusoidal DC drift removal unit for processing to obtain zero DC drift A sinusoidal signal sin1; the amplitude of the zero-DC drift sinusoidal signal sin1 is adjusted by the sinusoidal amplitude adjustment unit to obtain a corrected sinusoidal signal sin2, which is provided to the orthogonalization unit; The cosine differential amplifier unit receives and processes two cosine signals cos+ and cos- with a phase difference of 180° to obtain a cosine differential amplification signal cos0 and provides it to the cosine de-DC drift unit for processing to obtain zero DC drift cosine signal cos1; the cosine amplitude adjustment unit adjusts the amplitude of the zero DC drift cosine signal cos1 to obtain a corrected cosine signal cos2, and provides it to the orthogonalization unit; The orthogonalization unit performs orthogonalization processing on the corrected sine signal sin2 and cosine signal cos2 to obtain sine signal sin and cosine signal cos that are strictly orthogonal, have equal amplitudes, and have zero DC drift. 2. The correction module of sine and cosine measurement signal according to claim 1, is characterized in that, described sine removes DC drift unit or cosine removes DC drift unit and comprises: low-pass filter and adding circuit; Obtain the DC drift signal in the received one-way sine differential amplification signal sin0 or one-way cosine differential amplification signal cos0 by the low-pass filter, and provide it to the adding circuit for removing the DC drift signal, thereby Get zero DC drift sine signal sin1 or zero DC drift cosine signal cos1. 3. The correction module of the sine and cosine measurement signal according to claim 1, characterized in that, the sine amplitude adjustment unit or the cosine amplitude adjustment unit comprises: a first absolute value circuit, a sample and hold circuit, a differential circuit, a second Two absolute value circuits, window comparators and division circuits; The first absolute value circuit performs absolute value processing on the zero DC drift sine signal sin1 or the zero DC drift cosine signal cos1, and the obtained result is provided to the sample and hold circuit; The differential circuit performs differential processing on the zero DC drift sine signal sin1 or the zero DC drift cosine signal cos1 to obtain a differential signal and provide it to the second absolute value circuit; the second absolute value circuit performs differential processing on the differential signal The signal is processed by taking the absolute value, and the obtained result is provided to the window comparator for processing, and the trigger signal is obtained and sent to the sample and hold circuit; The sample-and-hold circuit performs real-time amplitude acquisition on the processing result of the first absolute value circuit according to the received trigger signal, thereby obtaining continuously changing amplitude information and providing it to the division circuit; The division circuit divides the zero DC drift sine signal sin1 or the zero DC drift cosine signal cos1 and the amplitude information to obtain the corrected sine signal sin2 and cosine signal cos2. 4. The correction module of sine and cosine measurement signals according to claim 1, characterized in that, when the amplitude changes of the zero DC drift sine signal sin1 or the zero DC drift cosine signal cos1 are synchronized, the sine amplitude adjustment The unit and the cosine amplitude adjustment unit can also adjust the amplitude of the zero-DC drift sine signal sin1 or the zero-DC drift cosine signal cos1 by using a resistor divider method to obtain a sine signal sin2 and a cosine signal cos2 with equal amplitudes after correction. 5. A correction method for a sine-cosine measurement signal, characterized in that it is carried out as follows: Step 1. Perform differential amplification processing on two sinusoidal signals sin+ and sin- with a phase difference of 180° to obtain a sinusoidal differential amplification signal sin0; at the same time, two cosine signals cos+ and cos- with a phase difference of 180° Perform differential amplification processing to obtain a cosine differential amplification signal cos0; Step 2, using a low-pass filter to obtain the DC drift signal in the one-way sine differential amplification signal sin0 or one-way cosine differential amplification signal cos0, and using an addition circuit to remove the one-way sine differential amplification signal sin0 or one-way cosine difference Dynamically amplify the DC drift signal in the signal cos0 to obtain a zero DC drift sine signal sin1 and a zero DC drift cosine signal cos1; Step 3. Equal amplitude adjustment is performed on the zero DC drift sine signal sin1 and the zero DC drift cosine signal cos1 to obtain the corrected sine signal sin2 and cosine signal cos2; Step 3.1, performing absolute value processing on the zero-DC-drift sine signal sin1 and the zero-DC-drift cosine signal cos1 respectively, to obtain a corresponding first absolute value result for amplitude acquisition; Step 3.2: Carry out differential processing on the zero DC drift sine signal sin1 and zero DC drift cosine signal cos1 respectively, then take the absolute value, obtain the corresponding second absolute value result, and then perform window comparison to obtain the corresponding amplitude acquisition trigger Signal; Step 3.3, according to the corresponding amplitude acquisition trigger signal, respectively perform real-time amplitude acquisition on the corresponding first absolute value results, so as to obtain corresponding continuously changing amplitude information; Step 3.4, divide the zero-DC-drift sine signal sin1 and the zero-DC-drift cosine signal cos1 by the corresponding amplitude information respectively, so as to obtain the corrected sine signal sin2 and cosine signal cos2; Step 4. Orthogonalize the corrected sine signal sin2 and cosine signal cos2 to obtain sine signal sin and cosine signal cos that are strictly orthogonal, have equal amplitudes, and have zero DC drift.