A nonlinear adaptive angular position control method for AC servo motors

Abstract

This invention discloses a nonlinear adaptive AC servo motor angular position control method, relating to the field of motor angular position control technology. The invention includes: S1: Selecting a servo motor and a CPU controlling the servo motor according to requirements; setting a planar sensor and a timer T1 in the servo motor; setting a digital signal processing module in the CPU; pre-setting the CPU main program for the planar sensor in the digital signal processing module; the CPU main program initializes the system of the digital signal processing module and simultaneously initializes timer T1; S2: The CPU control program initializes the external analog-to-digital converter; S3: Starting timer T1 controlled by the CPU main program, timer T1 enters an infinite loop measurement, waiting for the timer T1 period to be interrupted. This invention, through an adjustment method based on the output signal of a planar inductive angular position sensor, can remove the carrier wave in the sensor signal and reduce noise in the sensor output signal.

Description

Technical Field

[0001] The invention belongs to the technical field of motor angular position control, and in particular relates to a nonlinear adaptive AC servo motor angular position control method. Background Art

[0002] In applications such as high-precision servo motor control systems, the accuracy of angular position and angular velocity feedback signals must be very high. Common measurement devices for obtaining these feedback signals are photoelectric encoders and resolvers. Photoelectric encoders can achieve very high accuracy, but they cannot work in harsh environments such as high temperature, severe cold, humidity, and severe vibration. Although resolvers can work in harsh environments, high-precision resolvers are very expensive, and the signals output by resolvers need to be decoded by expensive chips to obtain angular position and angular velocity.

[0003] The current planar inductive angular position sensor is a recently emerging high-precision, low-cost sensor that can adapt to harsh environments. The working principle and signal form of this sensor are similar to those of a rotary transformer, but due to the planar structure of its stator part, the coils on the stator are coupled to each other, thereby generating high-frequency coupling noise in the sensor output signal.

[0004] In the existing nonlinear adaptive AC servo motor angular position control measurement, the planar inductive angular position sensor has high-frequency coupling noise, and the photoelectric encoder has high accuracy but cannot be used in harsh environments such as high temperature. Therefore, we propose a nonlinear adaptive AC servo motor angular position control method. Summary of the invention

[0005] The purpose of the present invention is to provide a nonlinear adaptive AC servo motor angular position control method to solve the problem that in the existing nonlinear adaptive AC servo motor angular position control measurement, the planar inductive angular position sensor has high-frequency coupling noise, and the photoelectric encoder has high accuracy but cannot be used in harsh environments such as high temperature.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0007] The present invention is a nonlinear adaptive AC servo motor angular position control method, comprising the following steps:

[0008] S1: Select a servo motor and a CPU for controlling the servo motor according to the requirements, set a plane sensor and a timer T1 in the servo motor, set a digital signal processing module in the CPU, preset a CPU main program of the plane sensor in the digital signal processing module, and the CPU main program performs system initialization on the digital signal processing module, and at the same time, the CPU main program initializes the timer T1;

[0009] S2: The CPU main program initializes the off-chip analog-to-digital converter;

[0010] S3: start the timer T1 controlled by the CPU main program, the timer T1 enters an infinite loop measurement, and waits for the timer T1 period interruption, wherein the CPU is in an idle state during the main program waiting process;

[0011] S4: Select the motor rotor angle encoder, and input the measurement result of the main program into the electrode rotor angle encoder to obtain the current rotor angle position data of the motor;

[0012] S5: Obtain the target rotor angle position of the motor according to user requirements, compare the target rotor angle position with the current rotor angle position data, and determine whether the motor rotor angle data are equal;

[0013] S6: If they are not equal, the difference is calculated and input into the motor rotor angle position control module preset in the CPU, and adjustment is performed according to the standard rotor angle position and the current rotor angle position data.

[0014] When the timer period is interrupted, the main program jumps to the interrupt service program to execute the timer interrupt service program, the timer interrupt service program performs analog-to-digital conversion to obtain the digital quantity of the demodulated output sine signal and the digital quantity of the cosine signal, the timer interrupt service program starts to execute the three-phase synchronous phase-locked loop (SRF-PLL) or dual synchronous reference frame phase-locked loop (DSRF-PLL) algorithm program, and finally, the timer interrupt service program clears the interrupt flag. The timer interrupt service program returns to the main program and waits for the next timer period interrupt.

[0015] It also includes a photoelectric encoder, which is an incremental photoelectric encoder. One rotation can generate 2500 pulses. The photoelectric encoder outputs three pairs of mutually anti-phase signals A+, A-; B+, B-; Z+, Z-, which are respectively an angular position A phase signal pair, an angular position B phase signal pair and a zero mark signal pair. The two signals in each signal pair contain common mode noise, and the signals are differentially processed to obtain one signal.

[0016] The signal after the differentiation is optically isolated, firstly to further reduce noise, and secondly to protect the safety of some devices and human body. The output signal of the optical coupler is connected to the QEP module of DSP. The QEP module will extract the steering information from the two-phase signals A and B with a phase difference of 90 degrees, and the QEP module will generate new counting pulses at the rising and falling edges of A and B. In this way, when the photoelectric encoder rotates one circle, the QEP module will generate 4 times the number of pulses, which is equivalent to increasing the accuracy of the photoelectric encoder by 4 times.

[0017] The invention comprises a measuring body, a planar inductive angular position sensor, a motor, an incremental photoelectric encoder, a photoelectric encoder output signal distributor and a motor driver. The sensor used in the motor driver is a photoelectric encoder installed on the motor.

[0018] The planar inductive angular position sensor is installed on the motor, the sensor stator is stationary, and the sensor rotor can rotate with the motor. Then the remaining parts of the measurement system based on the planar inductive sensor are connected to the stator of the planar inductive angular position sensor through cables. In order to evaluate the performance of the measurement system based on the planar inductive sensor, a measurement device based on a photoelectric encoder is also required. It is only necessary to connect the output signal of the photoelectric encoder to the measurement device based on the photoelectric encoder (differential and optical coupling isolation circuit) through a homemade photoelectric encoder output signal splitter. The digital quantities obtained by analog-to-digital conversion are stored in the PC through the DSP program development software CCS for easy analysis. Plotting or analyzing these data are all carried out in MATLAB software.

[0019] The digital quantities obtained by the analog-to-digital conversion are stored in the PC through the development software debugger of the digital signal processing module.

[0020] The present invention has the following beneficial effects:

[0021] The planar inductive angular position sensor used in the present invention has the advantages of low cost, high accuracy and adaptability to harsh environments. It can replace the photoelectric encoders and rotary transformers currently widely used in the field of motor angular position control. At the same time, the adjustment method based on the output signal of the planar inductive angular position sensor can effectively remove the carrier in the sensor signal and reduce the noise in the sensor output signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 It is the main program flow chart of the present invention;

[0024] Figure 2 It is a flow chart of the timer interrupt service program in the present invention;

[0025] Figure 3 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0026] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0027] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] See also Figure 1-3 The present invention is a nonlinear adaptive AC servo motor angular position control method, comprising the following steps:

[0030] The present invention is a nonlinear adaptive AC servo motor angular position control method, comprising the following steps:

[0031] S1: Select a servo motor and a CPU for controlling the servo motor according to the requirements, set a plane sensor and a timer T1 in the servo motor, set a digital signal processing module in the CPU, preset a CPU main program of the plane sensor in the digital signal processing module, and the CPU main program performs system initialization on the digital signal processing module, and at the same time, the CPU main program initializes the timer T1;

[0032] S2: The CPU controls the main program to initialize the off-chip analog-to-digital converter;

[0033] S3: start the timer T1 controlled by the CPU main program, the timer T1 enters an infinite loop measurement, and waits for the timer T1 period interruption, wherein the CPU is in an idle state during the main program waiting process;

[0034] S4: Select the motor rotor angle encoder, and input the measurement result of the main program into the electrode rotor angle encoder to obtain the current rotor angle position data of the motor;

[0035] S5: Obtain the target rotor angle position of the motor according to user requirements, compare the target rotor angle position with the current rotor angle position data, and determine whether the motor rotor angle data are equal;

[0036] S6: If they are not equal, the difference is calculated and input into the motor rotor angle position control module preset in the CPU, and adjustment is performed according to the standard rotor angle position and the current rotor angle position data.

[0037] When the timer period interrupts, the main program jumps to the interrupt service program to execute the timer interrupt service program. The timer interrupt service program performs analog-to-digital conversion to obtain the digital quantity of the demodulated output sine signal and the digital quantity of the cosine signal. The timer interrupt service program starts to execute the three-phase synchronous phase-locked loop (SRF-PLL) or dual synchronous reference phase-locked loop (DSRF-PLL) algorithm program. Finally, the timer interrupt service program clears the interrupt flag. The timer interrupt service program returns to the main program and waits for the next timer period interrupt.

[0038] It also includes a photoelectric encoder, which is an incremental photoelectric encoder. One rotation can generate 2500 pulses. The photoelectric encoder outputs three pairs of anti-phase signals A+, A-; B+, B-; Z+, Z-, which are angular position A phase signal pair, angular position B phase signal pair and zero mark signal pair respectively. The two signals in each signal pair contain common mode noise, and the signals are differentially processed to obtain one signal.

[0039] The signal after differentiation is isolated by optical coupling, firstly to further reduce noise, and secondly to protect the safety of some devices and human body. The output signal of the optical coupling is connected to the QEP module of DSP. The QEP module will extract the steering information from the two-phase signals A and B with a phase difference of 90 degrees, and the QEP module will generate new counting pulses at the rising and falling edges of A and B. In this way, when the photoelectric encoder rotates one circle, the QEP module will generate 4 times the number of pulses, which is equivalent to increasing the accuracy of the photoelectric encoder by 4 times.

[0040] It includes a measuring body, a planar inductive angular position sensor, a motor, an incremental photoelectric encoder, a photoelectric encoder output signal distributor and a motor driver. The sensor used in the motor driver is a photoelectric encoder installed on the motor.

[0041] The planar inductive angular position sensor is installed on the motor. The sensor stator is stationary, and the sensor rotor can rotate with the motor. Then the remaining components of the measurement system based on the planar inductive sensor are connected to the stator of the planar inductive angular position sensor through cables. In order to evaluate the performance of the measurement system based on the planar inductive sensor, a measurement device based on a photoelectric encoder is also required. It is only necessary to connect the output signal of the photoelectric encoder to the measurement device based on the photoelectric encoder (differential and optical coupling isolation circuit) through a homemade photoelectric encoder output signal splitter. The digital quantities obtained by analog-to-digital conversion are saved in the PC through the DSP program development software CCS for easy analysis. Plotting or analyzing these data are all done in MATLAB software.

[0042] The digital quantities obtained by analog-to-digital conversion are saved in the PC through the development software debugger of the digital signal processing module.

[0043] The planar sensor consists of two parts: the stator and the rotor. The stator is a 4-layer PCB with copper foil coils in each layer, including 1 excitation coil, 1 sine coil and 1 cosine coil. The rotor is an LC resonator, consisting of a 20mm long ferrite rod (inductor) and a capacitor wound by the coil. When the sensor is in use, the stator remains stationary and the rotor rotates with the rotating object being measured.

[0044] First, give the excitation coil a sinusoidal excitation voltage:

[0045] v e =V e sin(ω e t)

[0046] Among them, v e is the amplitude of the excitation voltage, ω e =2πfe is the excitation angular frequency. The excitation frequency fe is generally 100k to 4MHz.

[0047] The sinusoidal excitation voltage generates an alternating excitation current in the excitation coil, and the alternating excitation current excites an alternating magnetic field. The rotor is in this alternating magnetic field. The rotor is an LC resonator, and its resonant frequency is equal to the excitation frequency. The alternating electromotive force induced in the LC resonator loop generates a large alternating current. The alternating current in the LC resonator excites an alternating magnetic field. The stator's sine coil and cosine coil are in this alternating magnetic field, and they each induce a voltage signal

[23] . Due to the special structure of the sensor, the voltage signals on the sine coil and cosine coil are functions of the angular position:

[0048] v s =Vsin(θ m )sin(ω c t+90°)+cs

[0049] v c =Vcos(θ m )sin(ω c t+90°)+c c

[0050] Where V is a constant, θ m is the angular position of the object being measured, ω c is the carrier angular frequency, c s and c c These are the coupled noises on the two coils respectively.

[0051] Carrier angular frequency ω c Equal to the excitation angular frequency ω e .v s and v c The reason for the coupling noise on the sensor is that the three coils on the sensor stator are on the same PCB, and the coupling noise is the superposition of odd harmonics of the carrier.

[0052] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A nonlinear adaptive AC servo motor angular position control method, characterized in that: The following steps are involved: S1: Select a servo motor and a CPU for controlling the servo motor according to the requirements, set a plane sensor and a timer T1 in the servo motor, set a digital signal processing module in the CPU, preset a CPU main program of the plane sensor in the digital signal processing module, and the CPU main program performs system initialization on the digital signal processing module, and at the same time, the CPU main program initializes the timer T1; S2: The CPU controls the main program to initialize the preset off-chip analog-to-digital converter; S3: start the timer T1 controlled by the CPU main program, the timer T1 enters an infinite loop measurement, and waits for the timer T1 period interruption, wherein the CPU is in an idle state during the main program waiting process; S4: Select the motor rotor angle encoder, and input the measurement result of the main program into the electrode rotor angle encoder to obtain the current rotor angle position data of the motor; S5: Obtain the target rotor angle position of the motor according to user requirements, compare the target rotor angle position with the current rotor angle position data, and determine whether the motor rotor angle data are equal; S6: If they are not equal, the difference is calculated and input into the motor rotor angle position control module preset in the CPU, and the traditional PID algorithm is used to calculate and adjust according to the standard rotor angle position and the current rotor angle position data.

2. A nonlinear adaptive AC servo motor angular position control method according to claim 1, characterized in that: When the timer period is interrupted, the main program jumps to the interrupt service program to execute the timer interrupt service program. The timer interrupt service program performs analog-to-digital conversion to obtain the digital quantity of the demodulated output sine signal and the digital quantity of the cosine signal. The timer interrupt service program starts to execute the three-phase synchronous phase-locked loop or dual synchronous reference phase-locked loop algorithm program. Finally, the timer interrupt service program clears the interrupt flag, and the timer interrupt service program returns to the main program to wait for the next timer period interrupt.

3. A nonlinear adaptive AC servo motor angular position control method according to claim 2, characterized in that: It also includes a photoelectric encoder, which is an incremental photoelectric encoder. One rotation can generate 2500 pulses. The photoelectric encoder outputs three pairs of mutually anti-phase signals A+, A-; B+, B-; Z+, Z-, which are respectively an angular position A phase signal pair, an angular position B phase signal pair and a zero mark signal pair. The two signals in each signal pair contain common mode noise, and the signals are differentially processed to obtain one signal.

4. A nonlinear adaptive AC servo motor angular position control method according to claim 3, characterized in that: The signal after the differentiation is optically isolated, and the output signal of the optical coupler is connected to the orthogonal coding pulse circuit module of the digital signal processing module. The orthogonal coding pulse circuit module extracts the steering information from the A and B two-phase signals with a phase difference of 90.

5. A nonlinear adaptive AC servo motor angular position control method according to claim 4, characterized in that: It also includes a measuring platform, which includes a measuring body, a planar inductive angular position sensor, a motor, an incremental photoelectric encoder, a photoelectric encoder output signal splitter and a motor driver. The measuring platform is mainly used to measure the current motor rotor angular position. The measuring body is the motor, the measuring system is the CPU main control program, the sensor used by the motor driver is a photoelectric encoder installed on the motor, and there is an electrical connection between the planar inductive angular position sensor, the motor, the incremental photoelectric encoder, the photoelectric encoder output signal splitter and the motor driver.

6. A nonlinear adaptive AC servo motor angular position control method according to claim 5, characterized in that: The digital quantities obtained by the analog-to-digital conversion are stored in the PC through the development software debugger of the digital signal processing module.

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