CN106788440B - Preprocessing circuit of incremental sine and cosine encoder signal - Google Patents
Preprocessing circuit of incremental sine and cosine encoder signal Download PDFInfo
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Abstract
The invention discloses a preprocessing circuit for an incremental sine and cosine encoder signal. The preprocessing circuit outputs a preprocessing signal with safety and redundancy functions. The two proportional amplification differential shaping circuits respectively perform differential shaping and proportional amplification on the sine increment signals A+ and A-, and the cosine increment signals B+ and B-, so as to generate a pair of Asinα and Bcosα with 90-degree phase difference, and then an adder, a subtracter and an inverter perform corresponding analog quantity addition operation to output Asin (α+45°) and-Bcose (α+45°). The two comparators convert Asinα and Bcosα into corresponding square wave signals and perform cross redundancy respectively. The last proportional amplifying differential shaping circuit is matched with the last comparator to convert a pair of reference point increment signals R+ and R-into a reference point R square wave signal. Each frame of the pre-processed signal includes the above nine signals.
Description
Technical Field
The present invention relates to a preprocessing circuit, and more particularly, to a preprocessing circuit for an incremental sine and cosine encoder signal.
Background
The signal preprocessing is a process of preprocessing various types of electric signals, namely processing the signals recorded on a certain medium according to various expected purposes and requirements, so as to extract useful information, and is a process of extracting, transforming, analyzing, synthesizing and the like.
The incremental sine and cosine encoder must pre-process the original signal of the encoder before performing coarse position counting or fine position interpolation. On the one hand, the preprocessing circuit provides an ideal square wave signal source for a coarse position counting unit (coarse position counting, namely 4 times frequency multiplication is firstly carried out on the square wave signal, and then the real-time position of a motor rotor is calculated) in a subsequent DSP (digital signal processor); on the other hand, the preprocessing circuit provides an ideal analog signal source for the accurate position interpolation unit in the subsequent DSP. The accurate position interpolation is to divide one period of the analog signal into a plurality of equal signal segments, and only one trigger pulse is generated in one period of the analog signal, and a plurality of trigger pulses are generated after interpolation is divided into a plurality of equal signal segments. The resolution of the counting system is improved. For example, the number of lines of an incremental sine-cosine encoder is 2048 (2048 signal cycles are generated per revolution), and after 4 times the frequency, the physical resolution of the incremental sine-cosine encoder=one cycle of the analog signal/4=360×3600/(2048×4) = 158.203125 radians seconds, which is the resolution of the coarse position counting unit in the DSP for counting the positions of the motor rotor. The conventional square wave signal processing method and circuit for the encoder cannot break through the concept of frequency multiplication by 4 (more frequency multiplication will distort the position signal), so that higher resolution of the rotor position counting system cannot be obtained.
Disclosure of Invention
In order to solve the technical problems, the invention provides a preprocessing circuit of an incremental sine and cosine encoder signal, which outputs a preprocessing signal with safety and redundancy functions.
The solution of the invention is as follows: a preprocessing circuit of an incremental sine and cosine encoder signal comprises an adder, a subtracter, an inverter, three proportional amplifying differential shaping circuits and three comparators; the preprocessing circuit is used for outputting a preprocessing signal with safety and redundancy functions, and each frame of the preprocessing signal comprises the following signals:
asinα: the proportional amplification differential shaping circuit performs differential shaping and proportional amplification on a pair of sine increment signals A+ and A-, which are output by the pair of increment sine and cosine encoders, so as to generate an A-phase sine signal Asinα;
bcos α: the proportional amplification differential shaping circuit performs differential shaping and proportional amplification on a pair of cosine increment signals B+ and B < - > output by the two pairs of increment type sine and cosine encoders to generate a B-phase cosine signal Bcosa; wherein, the phase difference between the A phase sine signal Asinα and the B phase cosine signal Bcosα is 90 degrees;
asin (α+45°): the adder performs analog addition operation on the A-phase sine signal Asin alpha and the B-phase cosine signal Bcosalpha to form a signalMultiplying by a coefficient->Obtaining an A-phase 45 DEG phase-shifted signal Asin (alpha+45 DEG) which is 45 DEG phase-shifted relative to the A-phase sinusoidal signal Asin alpha;
bcos (α+45°): the subtracter performs analog subtraction operation on the B-phase cosine signal Bcosa minus the A-phase sine signal Asinα to form a signalMultiplying by a coefficient->Obtaining a B-phase 45 DEG phase-shift signal Bco (alpha+45 DEG) which is phase-shifted by 45 DEG relative to a B-phase cosine signal Bco alpha, and generating an inversion signal Bco (alpha+45 DEG) by inverting the B-phase-shift signal Bco (alpha+45 DEG);
s_a_1: the comparator I converts the A-phase sinusoidal signal Asinα into an A-phase square wave signal S_A_1;
s_a_2: S_A_1 performs cross redundancy to generate an A-phase square wave redundancy signal S_A_2;
s_b_1: the second comparator converts the B-phase cosine signal Bcosα into a B-phase square wave signal S_B_1;
s_b_2: S_B_1 performs cross redundancy to generate a B-phase square wave redundancy signal S_B_2;
S_R: and the three pairs of reference point increment signals R+ and R-output by the three pairs of increment sine and cosine encoders of the proportional amplification differential shaping circuit are subjected to differential shaping and proportional amplification and then converted into reference point R square wave signals S_R by the three comparators.
As a further improvement of the above-described scheme, each proportional amplifying differential shaping circuit includes a differential shaping circuit that performs differential shaping on the input signal and a proportional amplifying circuit that performs proportional amplification.
As a further improvement of the scheme, each proportional amplifying differential shaping circuit comprises resistors R1-R6, a resistor R20, capacitors C1-C5, a capacitor C7 and operational amplifiers U1-U3; the sinusoidal increment signal A+ is input into the in-phase end of the operational amplifier U1, the sinusoidal increment signal A-is input into the in-phase end of the operational amplifier U2, a resistor R1 is connected in series between the two in-phase ends of the operational amplifier U1 and the operational amplifier U2, the two in-phase ends of the operational amplifier U1 and the operational amplifier U2 are respectively connected with the capacitors C1 and C2 in parallel, a first-order RC filter is built, and the two opposite-phase ends of the operational amplifier U1 and the operational amplifier U2 are respectively connected with the respective output ends to form negative feedback; the output end of the operational amplifier U1 is connected with the in-phase end of the operational amplifier U3 through a resistor R2, the output end of the operational amplifier U2 is connected with the anti-phase end of the operational amplifier U3 through a resistor R3, the in-phase end of the operational amplifier U3 is grounded through capacitors C4 and C3, the resistor R4 is connected in parallel with the capacitor C4, and a power supply is connected between the capacitors C4 and C3; the inverting terminal of the operational amplifier U3 is connected with the output terminal of the operational amplifier U3 through a capacitor C5, a resistor R5 is connected in parallel with the capacitor C5, one end of a capacitor C7 is connected between a resistor R6 and a resistor 20, and the other end of the capacitor C7 is grounded; the output end of the operational amplifier U3 is also used as the output end of the proportional amplifying differential shaping circuit through a resistor R6 and a resistor R20.
As a further improvement of the above scheme, the non-inverting terminal of the comparator receives the a-phase sinusoidal signal asinα, the inverting terminal of the comparator is connected to the power supply for use as a bias voltage, and the output terminal of the comparator outputs the a-phase square wave signal s_a_1 via a capacitor C6 to ground.
As a further improvement of the above scheme, the non-inverting terminal of the second comparator receives the B-phase cosine signal Bcos α, the inverting terminal of the second comparator is connected to the power supply for use as a bias voltage, and the output terminal of the second comparator outputs the B-phase square wave signal s_b_1 via a capacitor to ground.
As a further improvement of the above scheme, the output end of the proportional amplifying differential shaping circuit three is connected to the non-inverting end of the comparator three, the inverting end of the comparator three is connected to a power supply on one hand and used as a bias voltage, and on the other hand, is grounded via a capacitor, and the output end of the comparator three outputs a rectangular wave signal s_r of the reference point R.
As a further improvement of the above scheme, the adder includes resistors R7 to R11, an operational amplifier U5; the A-phase sine signal Asinα and the B-phase cosine signal Bcosα are respectively connected with the in-phase end of the operational amplifier U5 through a resistor R7 and a resistor R8, the anti-phase end of the operational amplifier U5 is grounded through a resistor R10, two ends of the resistor R9 are respectively connected with the anti-phase end and the output end of the operational amplifier U5, and the output end of the operational amplifier U5 outputs an A-phase 45 DEG phase-shifting signal Asin (alpha+45 DEG) through a resistor R11.
As a further improvement of the above scheme, the subtracter comprises resistors R12 to R16 and an operational amplifier U6; the A-phase sine signal Asinα is connected with the inverting terminal of the operational amplifier U6 through a resistor R12, the B-phase cosine signal Bcosα is connected with the non-inverting terminal of the operational amplifier U6 through a resistor R13, the non-inverting terminal of the operational amplifier U6 is grounded through a resistor R14, two ends of the resistor R15 are respectively connected with the inverting terminal and the output terminal of the operational amplifier U6, and the output terminal of the operational amplifier U6 outputs a signal through a resistor R16
As a further improvement of the above-described scheme, the inverter includes resistors R17 to R19, an operational amplifier U7; signal signalAn inverting terminal of the input operational amplifier U7, and the operational amplifier U7The same phase end is grounded through a resistor R17, two ends of a resistor R18 are respectively connected with an inverting end and an output end of the operational amplifier U7, and the output end of the operational amplifier U7 outputs an inversion signal Bco (alpha+45 degrees) through a resistor R19.
As a further development of the above scheme, the sine delta signals a+ and a-, the cosine delta signals b+ and B-, and the reference point delta signals r+ and R-are transmitted in a differential signal manner.
In the invention, the multifunctional signal output by preprocessing the signal of the incremental sine and cosine encoder provides various choices for downstream DSP processing, and can meet the demands of different users with different degrees. The preprocessing circuit can be designed into an IP core in an FPGA by using a hardware description language, and even can be designed and manufactured into a standard ASIC chip.
Drawings
Fig. 1 is a circuit configuration diagram of a preprocessing circuit of an incremental sine and cosine encoder signal.
Fig. 2 is an electrical connection diagram of the first and the first comparator of fig. 1.
Fig. 3 is a waveform diagram of sine and cosine signals of phase a and phase B, which are obtained by simulating the differential shaping circuit one and the differential shaping circuit two in fig. 1 by MATLAB, respectively, and have phases different by 90 degrees.
Fig. 4 is a graph of a phase square wave signal from a simulation of the first comparator of fig. 1 by MATLAB.
Fig. 5 is a circuit diagram of the adder of fig. 1.
Fig. 6 is a waveform diagram of the output signal from a simulation of the circuit of fig. 4 by MATLAB.
Fig. 7 is a circuit connection diagram of the subtractor and the inverter in fig. 1.
Fig. 8 is a waveform diagram of the output signal from a simulation of the circuit of fig. 7 by MATLAB.
Fig. 9 is a signal waveform diagram comparing the two-way signals ASin (a+45°) and-Bcos (a+45°) that are finally output in MATLAB.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1 to 9, the preprocessing circuit of the incremental sine and cosine encoder signal of the present invention is used for outputting the preprocessing signal with safety and redundancy functions, which is a great difference from the conventional preprocessing signal. Referring to fig. 1, the preprocessing circuit includes three proportional amplifying differential shaping circuits 1-3, three comparators 4-6, an adder 7, a subtracter 8, and an inverter 9.
Each frame of the pre-processed signal comprises the following signals asinα, bcos α, asin (α+45°), -Bcos (α+45°), s_a_1, s_a_2, s_b_1, s_b_2, s_r.
Asinα: and the proportional amplification differential shaping circuit performs differential shaping and proportional amplification on a pair of sine increment signals A+ and A-, which are output by the pair of increment sine and cosine encoders, so as to generate an A-phase sine signal Asinα.
Bcos α: the proportional amplification differential shaping circuit performs differential shaping and proportional amplification on a pair of cosine increment signals B+ and B < - > output by the two pairs of increment type sine and cosine encoders to generate a B-phase cosine signal Bcosa; wherein the phase of the a-phase sine signal asinα and the phase of the B-phase cosine signal Bcos α differ by 90 °.
Asin (α+45°): the adder 7 adds the analog quantity of the A-phase sine signal Asin alpha and the B-phase cosine signal Bcosa alpha to form a signalMultiplying by a coefficient->And obtaining an A-phase 45-degree phase-shift signal Asin (alpha+45 degrees) which is phase-shifted by 45 degrees relative to the A-phase sinusoidal signal Asin alpha.
－Bcos(α+45°): the subtracter 8 performs analog subtraction on the B-phase cosine signal Bcosa minus the A-phase sine signal Asinα to form a signalMultiplying by a coefficient->A B-phase 45 ° phase-shifted signal Bcos (α+45°) which is 45 ° shifted with respect to the B-phase cosine signal Bcos α is obtained, and is inverted by the inverter 9 to generate an inverted signal-Bcos (α+45°).
S_a_1: the comparator one converts the a-phase sinusoidal signal asinα into an a-phase square wave signal s_a_1.
S_a_2: S_A_1 performs cross redundancy to generate an A-phase square wave redundancy signal S_A_2.
S_b_1: the second comparator converts the B-phase cosine signal Bcos α into a B-phase square wave signal s_b_1.
S_b_2: and S_B_1 is subjected to redundancy to generate a B-phase square wave redundancy signal S_B_2.
S_R: and the three pairs of reference point increment signals R+ and R-output by the three pairs of increment sine and cosine encoders of the proportional amplification differential shaping circuit are subjected to differential shaping and proportional amplification and then converted into reference point R square wave signals S_R by the three comparators. The sine increment signals A+ and A-, the cosine increment signals B+ and B-, and the reference point increment signals R+ and R-are transmitted in a differential signal mode.
It should be noted that the present invention is not focused on these components themselves, such as the three proportional-plus-differential shaping circuits 1 to 3, the three comparators 4 to 6, the adder circuit 7, the subtractor 8, the inverter 9, etc., but rather refers to the concept of a preprocessing signal with safety and redundancy functions, which is mainly composed of these components (the three proportional-plus-differential shaping circuits 1 to 3, the three comparators 4 to 6, the adder circuit 7, the subtractor 8, the inverter 9, etc.), and which is required to complete the present invention. Just like circuits, the resistances, inductances, chips, etc. that make up the circuits are inherent in the prior art, but not because of their existence, it means that the circuits made up of them must be obvious and must be a routine choice for a person skilled in the art, otherwise, the continual innovation of the circuits is hampered, and the purpose of the patent laws is violated. The invention is intended to be expressed herein as: the electrical structure of the preprocessing circuit of the incremental sine and cosine encoder signal of the present invention is not retrieved before the application of the present invention, and the design of the preprocessing circuit of the incremental sine and cosine encoder signal of the present invention requires creative effort, at least not done by a person skilled in the art.
The typical amplitude of output voltage signals a and B is 1VPP for a 1VPP sine and cosine delta, with an electronic angle of 90 deg. phase difference, according to the hadamard encoder interface definition. The interface signals are three pairs of differential signals. In the preprocessing circuit of the present invention, differential shaping, proportional amplification, etc. are required for differential signals to obtain A, B two-phase signals, i.e., an a-phase sine signal asinα and a B-phase cosine signal Bcos α. Meanwhile, in order to obtain square wave signals (mainly referred to as square wave signals) by the A, B two-phase signals through the comparator, the obtained high and low levels are required to meet the requirements of sampling chips or FPGA pins and the like.
Referring to fig. 2, each proportional amplifying differential shaping circuit may include a differential shaping circuit that performs differential shaping on an input signal and a proportional amplifying circuit that performs proportional amplification. In this embodiment, each proportional amplifying differential shaping circuit includes resistors R1 to R6, resistor R20, capacitors C1 to C5, capacitor C7, and operational amplifiers U1 to U3.
The sine increment signal A+ is input into the in-phase end of the operational amplifier U1, the sine increment signal A-is input into the in-phase end of the operational amplifier U2, a resistor R1 is connected in series between the two in-phase ends of the operational amplifier U1 and the operational amplifier U2, the two in-phase ends of the operational amplifier U1 and the operational amplifier U2 are respectively connected with the capacitor C1 and the capacitor C2 in parallel, first-order RC filtering is built, and the two opposite-phase ends of the operational amplifier U1 and the operational amplifier U2 are respectively connected with the respective output ends to form negative feedback. The output end of the operational amplifier U1 is connected with the in-phase end of the operational amplifier U3 through a resistor R2, the output end of the operational amplifier U2 is connected with the anti-phase end of the operational amplifier U3 through a resistor R3, the in-phase end of the operational amplifier U3 is grounded through capacitors C4 and C3, the resistor R4 is connected in parallel with the capacitor C4, and a power supply is connected between the capacitors C4 and C3. The inverting terminal of the operational amplifier U3 is connected with the output terminal of the operational amplifier U3 through a capacitor C5, a resistor R5 is connected in parallel with the capacitor C5, one end of a capacitor C7 is connected between a resistor R6 and a resistor 20, and the other end of the capacitor C7 is grounded. The output end of the operational amplifier U3 is also used as the output end of the proportional amplifying differential shaping circuit through a resistor R6 and a resistor R20.
The output end of the proportional amplification differential shaping circuit I1 is connected with the non-inverting end of the comparator I4, so that the non-inverting end of the comparator I receives an A-phase sinusoidal signal Asinα, the inverting end of the comparator I4 is connected with a power supply Vcc to serve as bias voltage on one hand, and is grounded through a capacitor C6 on the other hand, and the output end of the comparator I4 outputs an A-phase square wave signal S_A_1. Similarly, the output end of the proportional amplifying differential shaping circuit 2 is connected to the in-phase end of the comparator 5, so that the in-phase end of the comparator receives the B-phase cosine signal Bcos α, the opposite-phase end of the comparator 5 is connected to a power supply (not shown) for being used as a bias voltage, and is grounded via a capacitor (not shown), and the output end of the comparator 5 outputs the B-phase square wave signal s_b_1. The output end of the proportional amplifying differential shaping circuit three 3 is connected with the non-inverting end of the comparator three 6, the inverting end of the comparator three 6 is connected with a power supply (not shown) to serve as bias voltage, and the output end of the comparator three 6 is grounded through a capacitor (not shown) to output a reference point R square wave signal S_R.
The sinusoidal incremental signals a and B coming out of the encoder interface are a pair of differential signals with an amplitude of 1V, which are 90 degrees apart, where the differential signals a and B are processed separately. Taking differential signals A+ and A-as an example, amplifying the signals respectively through two paths of amplifiers U1 and U2, then entering an amplifier U3 for differential integration, outputting a path of sinusoidal signal Asin alpha with the amplitude range of 0V-3.3V, simultaneously inputting the sinusoidal signal Asin alpha into a comparator U4, and obtaining a path of signal similar to a square wave according to the characteristic parameters of the comparator through the bias voltage of 1.5V, wherein the amplitude range of the signal is 0.4V-2.6V. Fig. 4 and 3 are square wave signals obtained by simulating the differential shaping circuit in fig. 1 by MATLAB, and sine and cosine signal waveforms of a phase and B phase which are 90 degrees out of phase, respectively.
Referring to fig. 5, the adder includes resistors R7 to R11 and an operational amplifier U5. The Asina and Bcosa are respectively connected with the in-phase end of the operational amplifier U5 through resistors R7 and R8, the inverting end of the operational amplifier U5 is grounded through a resistor R10, the two ends of the resistor R9 are respectively connected with the inverting end and the output end of the operational amplifier U5, and the output end of the operational amplifier U5 outputs Asin (alpha+45 DEG) through a resistor R11.
The partial circuit is a single circuit of differential shaping, proportional amplification and comparison, and generates an A-phase sinusoidal signal Asinalpha. Finally, the square wave signals with the low level of 0.4V and the high level of 2.6V, namely the A-phase square wave signal S_A, are output through the comparison of the offset voltage of 1.5V. The inverting adder circuit 7 outputs a value of 0.707 (i.e) Is multiplied by the ratio of (c).
And at the same direction end of the adder U5, two paths of sine and cosine signals Asin alpha and Bco alpha which are output by the differential shaping circuit and have 90-degree phase difference are input, and meanwhile, the amplitudes of the two phases of sine and cosine signals are equal. To satisfy the following:
the above-described relationship coefficient is satisfied by adjusting the resistance values of the resistors R8, R7, R10, and R9 in fig. 5.
According to the virtual break, no current passes through the same directional input terminal, resulting in equal current through resistors R8 and R7, and equal current through resistors R10 and R9.
Thus:
according to the broken line of the virtual machine,
V + ＝V -
from this, it can be derived that:
fig. 6 is a waveform of an output signal obtained by simulating a circuit by MATLAB, and in fig. 6, it can be seen that, after two-phase signals of phase a and phase B are input to the same direction end of the adder, the waveform is shifted by 45 ° and the amplitude is increased by about 1.414 times, and the waveform of the output signal Asin (α+45°) can be obtained by reducing the amplitude by 0.707 times by adjusting the resistance values of the resistors R8, R7, R10 and R9.
Referring to fig. 7, the subtracter includes resistors R12 to R16 and an operational amplifier U6. The A-phase sine signal Asinα is connected with the inverting terminal of the operational amplifier U6 through a resistor R12, the B-phase cosine signal Bcosα is connected with the non-inverting terminal of the operational amplifier U6 through a resistor R13, the non-inverting terminal of the operational amplifier U6 is grounded through a resistor R14, two ends of the resistor R15 are respectively connected with the inverting terminal and the output terminal of the operational amplifier U6, and the output terminal of the operational amplifier U6 outputs a signal through a resistor R16
The inverter includes resistors R17 to R19 and an operational amplifier U7. Signal signalThe inverting terminal of the operational amplifier U7 is input, the non-inverting terminal of the operational amplifier U7 is grounded through a resistor R17, two ends of a resistor R18 are respectively connected with the inverting terminal and the output terminal of the operational amplifier U7, and the output terminal of the operational amplifier U7 outputs a B-phase 45 DEG phase-shifting and inverting signal-Bco (alpha+45 DEG) through a resistor R19.
For the accurate position interpolation unit in the DSP, for example, the interpolation unit performs time division interpolation on one period of the analog signal, for example, the interpolation unit divides the period into 8 equal parts, so that the interpolated resolution=one period/8=360×3600/(2048×8) = 79.1015625 radians seconds of the analog signal, which is the resolution of the rotor position counting system obtained by performing 8 equal division interpolation subdivision on one period of the signal, and obviously, the resolution is improved by 1 time compared with the coarse position counting resolution. For another example, a high-precision CNC machine requires rotor position accuracy of ±5 radians, and then the number of interpolation subdivisions required for a signal cycle=360×3600/(2×5×2048) = 63.28125, i.e. only 64 equal divisions of interpolation processing is required for a signal cycle, so that rotor position accuracy of less than ±5 radians is obtained.
In addition to receiving signals Asin alpha and Bcos alpha from the preprocessing circuit and performing rotor real-time position and real-time speed calculation according to the signals, the DSP also receives safety signals Asin (alpha+45°) and-Bcos (alpha+45°) from the preprocessing circuit and performs rotor real-time position and real-time speed calculation according to the safety signals, the DSP performs cross comparison on two groups of calculation results of the rotor real-time position and the rotor real-time speed, and performs safety operation on the comparison results.
And inputting sine and cosine signals Asin alpha and Bco alpha which are output by the differential shaping circuit and have 90-degree phase difference into different directional ends of the subtracter, wherein the amplitudes of the two sine and cosine signals are equal, and simultaneously inputting the obtained output signals into the inverter for inversion. To satisfy the following:
the above-described relationship coefficient is satisfied by adjusting the resistance values of the resistors R13, R12, R14, and R15 in fig. 7.
According to the virtual break, no current passes through the U6 unidirectional input, resulting in equal current through resistors R12 and R13, and equal current through resistors R14 and R15.
Thus:
according to the broken line of the virtual machine,
V + ＝V -
from this, it can be derived that:
the obtained cosine signal with the amplitude increased by about 1.414 times is input into an inverter, and the amplitude is reduced by 0.707 times and the phase is inverted by 180 degrees by adjusting the resistance values of the resistors R16 and R18.
In U7, the same-direction ground of the operational amplifier is grounded. According to the virtual short, the reverse terminal voltage is 0V. According to the virtual break, the reverse input terminal inputs a high resistance, almost no current is input and output, the resistors R16 and R18 are connected in series, and the current passing through the resistors R16 and R18 is equal.
Current through resistor R16:
current through resistor R18: i 7 ＝(V _ -Vout)/R 18
According to deficiency, V + ＝V _
From this, it can be derived that:
FIG. 8 is a waveform of an output signal obtained by simulating the circuit of FIG. 7 with MATLAB, in which it can be seen that the waveform is phase shifted by 45 degrees after subtractor processing by inputting two phase signals of A and B at different directional ends of the subtractor, and the amplitude is increased by about 1.414 times by adjusting the resistance values of R13, R12, R14 and R15 to obtain an output signalThe waveform of the output signal Bco (alpha+45°) can be obtained by adjusting the resistance values of R16 and R18 to reduce the amplitude by 0.707 times and simultaneously inverting the phase.
Fig. 9 shows that two paths of signals Asin (α+45°) and-Bcos (α+45°) which are finally output are compared in MATLAB, and after being processed by an adder and a subtracter and an inverter from the start point of the output signal, the two paths of sine and cosine signals Asin (α+45°) and-Bcos (α+45°) have a phase difference of 135 °, but from the continuous view of the signals, the processed signals have a phase difference of 90 degrees as the phase difference of the phase a and the phase B two-phase signals. Therefore, the phase difference at the beginning of the signal is negligible.
The processing of the encoder signals includes DSP processing (coarse position counting and fine position interpolation) and encoder signal preprocessing. The processing of the incremental sine and cosine encoder signals is a key and unique way for obtaining the real-time position of the rotor of the servo motor (particularly the real-time position of the rotor with high resolution), and is a necessary material foundation for improving the precision of a servo shaft (comprising a linear shaft and a rotating shaft) by using execution components such as a high-precision CNC machine tool, a servo manipulator, a numerical control rotary table, a multifunctional numerical control angle milling head, an electric spindle and the like. The processing (counting and safety) and digitization of encoder signals are all the time short plates of the national equipment manufacturing industry, and the precision of position detection and feedback of high-grade numerical control machine tools and alternating current servo transmission in China is improved to be raised to the national height for breaking western technical monopoly. The document "Innovative development engineering implementation of Intelligent manufacturing equipment" (modified from high skill [2014] 2072) requires, in the description of an all-digital AC servo system, the implementation of the full digitization of the AC servo drive internal control and measurement unit. The AC servo drive internal control and measurement unit mentioned in the document refers to an AC servo permanent magnet synchronous motor widely used in CNC field and a sine and cosine signal encoder in the motor. It can be seen that the significance of the processing of the sine-cosine signal encoder signal is significant.
There are a number of documents that propose circuits or methods for multiplying 4 times the square wave signal of an encoder (mainly a TTL signal encoder) and then performing a coarse position count; there are few documents that mention a method of square-wave processing an analog signal of an incremental sine-cosine encoder, converting the analog signal into a square-wave signal, and then performing coarse position counting by using a method similar to the method of processing the square-wave signal encoder, such as patent documents ZL201520574867.8, ZL201520570360.5, 201510465550.5, 201510467898.8, 201510465547.3, 201610517319.0, 201610518856.7, 2016120690307.3 (hereinafter referred to as patent document combinations) all refer to a method of converting an analog signal of an incremental sine-cosine encoder into a square-wave signal and then performing coarse position counting; the patent literature combination also mentions that the phase shift of the analog signal of the incremental sine and cosine encoder is equal to the preprocessing, and then the DSP is utilized to conduct accurate position interpolation, so that the process flow of more accurate real-time position of the rotor of the servo motor is obtained; the patent literature combination also mentions the process flow of the security encoder signal. The patent literature combination does not suggest a detailed implementation method of the preprocessing circuit and a theoretical basis of the implementation thereof.
In addition, in order to enhance confidentiality of the encoder signal preprocessing and post-processing, developed countries have adopted more efficient methods than the patented methods, i.e., designing an IP core for the encoder signal preprocessing and post-processing, encapsulating design circuits and algorithms into the IP core, and users purchase the use, and cannot know why the use is made; even special ASIC chips are designed and manufactured.
The processing of the encoder signal comprises two parts, namely DSP processing and encoder signal preprocessing, which have very important functions and are indispensable. The DSP processing is mainly responsible for algorithm processing and is a theoretical basis; the encoder signal preprocessing is responsible for providing a proper signal source for the DSP algorithm and is a material basis. The preprocessing of the incremental sine and cosine encoder signal provided by the invention is responsible for providing a signal source for DSP processing (not described in the present case), and comprises the following specific contents: the method comprises the steps that A+, A-, B+, B-, R+ and R-six original (a sign A, B, R used in the invention is only used for distinguishing signal phases and does not have amplitude meaning, the amplitude 1VPP is the same as the amplitude) differential signals of an incremental sine-cosine encoder are subjected to a preprocessing circuit of the encoder signals to generate 9 paths of signals, the 9 paths of signals are provided for a DSP processing unit, square wave signals S_B_1 and S_A_1 are provided for rough position counting one (not in the scheme) of the DSP processing unit, and the rough position counting one is used for roughly counting the real-time position of a rotor of a servo motor; the square wave signals S_B_2 and S_A_2 are provided for a rough position count two (not in the scheme) of the DSP processing unit and are used for carrying out safety operation and CRC redundancy check on the result of the rough position count one and two pairs of the real-time position count of the servo motor rotor; S_R is a signal added by a full circle of the rotor, each S-R comes, rough position counts one and two are cleared, and a full circle counter is +1; the Asinα and Bcosα provide the accurate position interpolation one (not in the present case) for the DSP processing unit, and are used for accurately counting the interpolation subdivision of the real-time position of the servo motor rotor; the Asin (alpha+45 DEG) and the Bco (alpha+45 DEG) are provided for the accurate position interpolation II (not in the present case) of the DSP processing unit, and are used for carrying out accurate interpolation subdivision counting on the real-time position of the servo motor rotor; the accurate position interpolation performs a security operation and a CRC redundancy check on the count results of the first and second pairs.
The invention has the advantages that: not only a method for preprocessing the signal of the incremental sine and cosine encoder is provided, but also a practical implementation circuit is provided; the method comprises the steps of preprocessing an incremental sine and cosine encoder signal to obtain a square wave signal for coarse position counting, and conditioning the incremental sine and cosine encoder signal to obtain an analog signal for accurate position interpolation; the obtained square wave signals are subjected to normal rough position counting, and another square wave signal used for DSP processing and safety operation is generated; the obtained analog signals are subjected to normal and accurate position interpolation, and the other path of analog signals for performing security operation in DSP processing are obtained through shift-equal processing.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. A preprocessing circuit for an incremental sine and cosine encoder signal, which is characterized in that: the device comprises an adder, a subtracter, an inverter, three proportional amplifying differential shaping circuits and three comparators; the preprocessing circuit is used for outputting a preprocessing signal with safety and redundancy functions, and each frame of the preprocessing signal comprises the following signals:
asinα: the proportional amplification differential shaping circuit performs differential shaping and proportional amplification on a pair of sine increment signals A+ and A-, which are output by the pair of increment sine and cosine encoders, so as to generate an A-phase sine signal Asinα;
bcos α: the proportional amplification differential shaping circuit performs differential shaping and proportional amplification on a pair of cosine increment signals B+ and B < - > output by the two pairs of increment type sine and cosine encoders to generate a B-phase cosine signal Bcosa; wherein, the phase difference between the A phase sine signal Asinα and the B phase cosine signal Bcosα is 90 degrees;
asin (α+45°): the adder performs analog addition operation on the A-phase sine signal Asin alpha and the B-phase cosine signal Bcosalpha to form a signalMultiplying by a coefficient->Obtaining an A-phase 45 DEG phase-shifted signal Asin (alpha+45 DEG) which is 45 DEG phase-shifted relative to the A-phase sinusoidal signal Asin alpha;
bcos (α+45°): the subtracter performs analog subtraction operation on the B-phase cosine signal Bcosa minus the A-phase sine signal Asinα to form a signalMultiplying by a coefficient->Obtaining a B-phase 45 DEG phase-shift signal Bco (alpha+45 DEG) which is phase-shifted by 45 DEG relative to a B-phase cosine signal Bco alpha, and generating an inversion signal Bco (alpha+45 DEG) by inverting the B-phase-shift signal Bco (alpha+45 DEG);
s_a_1: the comparator I converts the A-phase sinusoidal signal Asinα into an A-phase square wave signal S_A_1;
s_a_2: S_A_1 carries out cross redundancy to generate an A-phase square wave redundancy signal S_A_2;
s_b_1: the second comparator converts the B-phase cosine signal Bcosα into a B-phase square wave signal S_B_1;
s_b_2: S_B_1 performs cross redundancy to generate a B-phase square wave redundancy signal S_B_2;
S_R: and the three pairs of reference point increment signals R+ and R-output by the three pairs of increment sine and cosine encoders of the proportional amplification differential shaping circuit are subjected to differential shaping and proportional amplification and then converted into reference point R square wave signals S_R by the three comparators.
2. The preprocessing circuit for an incremental sine-cosine encoder signal according to claim 1, wherein: each proportional amplifying differential shaping circuit comprises a differential shaping circuit for realizing differential shaping on an input signal and a proportional amplifying circuit for realizing proportional amplifying.
3. The preprocessing circuit for an incremental sine-cosine encoder signal according to claim 1, wherein: each proportional amplifying differential shaping circuit comprises resistors R1-R6, a resistor R20, capacitors C1-C5, a capacitor C7 and operational amplifiers U1-U3; the sinusoidal increment signal A+ is input into the in-phase end of the operational amplifier U1, the sinusoidal increment signal A-is input into the in-phase end of the operational amplifier U2, a resistor R1 is connected in series between the two in-phase ends of the operational amplifier U1 and the operational amplifier U2, the two in-phase ends of the operational amplifier U1 and the operational amplifier U2 are respectively connected with the capacitors C1 and C2 in parallel, a first-order RC filter is built, and the two opposite-phase ends of the operational amplifier U1 and the operational amplifier U2 are respectively connected with the respective output ends to form negative feedback; the output end of the operational amplifier U1 is connected with the in-phase end of the operational amplifier U3 through a resistor R2, the output end of the operational amplifier U2 is connected with the anti-phase end of the operational amplifier U3 through a resistor R3, the in-phase end of the operational amplifier U3 is grounded through capacitors C4 and C3, the resistor R4 is connected in parallel with the capacitor C4, and a power supply is connected between the capacitors C4 and C3; the inverting terminal of the operational amplifier U3 is connected with the output terminal of the operational amplifier U3 through a capacitor C5, a resistor R5 is connected in parallel with the capacitor C5, one end of a capacitor C7 is connected between a resistor R6 and a resistor 20, and the other end of the capacitor C7 is grounded; the output end of the operational amplifier U3 is also used as the output end of the proportional amplifying differential shaping circuit through a resistor R6 and a resistor R20.
4. The preprocessing circuit for an incremental sine-cosine encoder signal according to claim 1, wherein: the non-inverting terminal of the comparator receives the a-phase sinusoidal signal asina, the inverting terminal of the comparator is connected to a power supply for use as a bias voltage, and is grounded via a capacitor C6, and the output terminal of the comparator outputs an a-phase square wave signal s_a_1.
5. The preprocessing circuit for an incremental sine-cosine encoder signal according to claim 1, wherein: the non-inverting terminal of the second comparator receives the B-phase cosine signal Bcos α, the inverting terminal of the second comparator is connected to a power supply to serve as a bias voltage, and the inverting terminal of the second comparator is grounded via a capacitor to output the B-phase square wave signal s_b_1.
6. The preprocessing circuit for an incremental sine-cosine encoder signal according to claim 1, wherein: the output end of the proportional amplification differential shaping circuit III is connected with the same-phase end of the comparator III, the opposite-phase end of the comparator III is connected with a power supply to serve as bias voltage, and the other end of the comparator III is grounded through a capacitor to output a rectangular wave signal S_R of a reference point R.
7. The preprocessing circuit for an incremental sine-cosine encoder signal according to claim 1, wherein: the adder comprises resistors R7-R11 and an operational amplifier U5; the A-phase sine signal Asinα and the B-phase cosine signal Bcosα are respectively connected with the in-phase end of the operational amplifier U5 through a resistor R7 and a resistor R8, the anti-phase end of the operational amplifier U5 is grounded through a resistor R10, two ends of the resistor R9 are respectively connected with the anti-phase end and the output end of the operational amplifier U5, and the output end of the operational amplifier U5 outputs an A-phase 45 DEG phase-shifting signal Asin (alpha+45 DEG) through a resistor R11.
8. The preprocessing circuit for an incremental sine-cosine encoder signal according to claim 1, wherein: the subtracter comprises resistors R12-R16 and an operational amplifier U6; the A-phase sine signal Asinα is connected with the inverting terminal of the operational amplifier U6 through a resistor R12, the B-phase cosine signal Bcosα is connected with the non-inverting terminal of the operational amplifier U6 through a resistor R13, the non-inverting terminal of the operational amplifier U6 is grounded through a resistor R14, two ends of the resistor R15 are respectively connected with the inverting terminal and the output terminal of the operational amplifier U6, and the output terminal of the operational amplifier U6 outputs a signal through a resistor R16
9. The preprocessing circuit for an incremental sine-cosine encoder signal according to claim 1, wherein: the inverter comprises resistors R17-R19 and an operational amplifier U7; signal signalThe inverting terminal of the operational amplifier U7 is input, the non-inverting terminal of the operational amplifier U7 is grounded through a resistor R17, two ends of a resistor R18 are respectively connected with the inverting terminal and the output terminal of the operational amplifier U7, and the output terminal of the operational amplifier U7 outputs an inversion signal Bco (alpha+45°) through a resistor R19.
10. The preprocessing circuit for an incremental sine-cosine encoder signal according to claim 1, wherein: the sine increment signals A+ and A-, the cosine increment signals B+ and B-, and the reference point increment signals R+ and R-are transmitted in a differential signal mode.
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| CN110260797B (en) * | 2019-06-18 | 2020-06-26 | 西安交通大学 | Adaptive filtering method applied to constant/variable-speed grating signals |
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