Ultrasonic motor speed measuring device and speed measuring method

Abstract

The invention discloses an ultrasonic motor speed measuring device and a speed measuring method. The device comprises a single-chip microcomputer, a photoelectric encoder, a power supply module, an input setting module, an interface module and a communication module. The power module is used for supplying power to other modules; the input setting module is connected with the single-chip microcomputer and sets initial parameters for the single-chip microcomputer. The interface module is used for connecting the single-chip microcomputer and the photoelectric encoder and transmitting a measured output pulse signal to the single-chip microcomputer; the single-chip microcomputer is used for rotating speed calculation. And the communication module is used for transmitting the obtained rotating speed data to an upper computer. The speed measurement method of the ultrasonic motor device is used for performing formula calculation on pulse signals measured in unit time to obtain the rotating speed N of the ultrasonic motor. The technical scheme of the invention has the advantages of high speed measurement precision and short response time.

Description

Technical Field

[0001] The invention belongs to the technical field of ultrasonic motors, and in particular relates to an ultrasonic motor speed measuring device and a speed measuring method. Background Art

[0002] Ultrasonic motor is a new concept of motor with simple internal structure, no magnetic poles and windings. Compared with the traditional motor working on the principle of electromagnetic induction, it is easy to design in miniature, light weight, large torque at low speed, zero electromagnetic interference, high control accuracy, fast response when speed changes, and no noise interference. However, due to the particularity of the piezoelectric material of the ultrasonic motor, friction heating and environmental changes, the friction force driving the rotor produces serious nonlinear changes. This change greatly increases the difficulty of controlling the uniform rotation of the motor and the difficulty of measuring the motor speed. In addition, due to the miniaturization requirements of ultrasonic motors, it is impossible to build in sensors to measure the speed of the motor. The above problems have brought great challenges to the accurate measurement of the speed of ultrasonic motors.

[0003] In order to solve these problems, the current existing practice is to use a photoelectric tachometer to measure or connect a Hall sensor to the shaft of the ultrasonic motor to achieve speed measurement, but the former will cause a large speed measurement error, and the latter has problems of signal variation with temperature and nonlinear output. Therefore, the present invention designs a speed measurement device and measurement method for an ultrasonic motor based on a photoelectric encoder and a single-chip microcomputer, which can effectively reduce the speed measurement error and improve the speed measurement accuracy. Summary of the invention

[0004] The present invention designs an ultrasonic motor speed measuring device, comprising: a single chip microcomputer, a photoelectric encoder, a power supply module, an input setting module, an interface module and a communication module;

[0005] The power supply module is respectively connected to the single-chip microcomputer, the input setting module, the interface module and the communication module, and is used to supply power to other modules; the input setting module is connected to the single-chip microcomputer, and is used to set parameters for the single-chip microcomputer; the output end of the interface module is connected to the single-chip microcomputer, and the input end of the interface module is respectively connected to the A, B, and Z three-phases of the photoelectric encoder, and the interface module is used to transmit the pulse signal of the photoelectric encoder to the single-chip microcomputer; the single-chip microcomputer calculates the speed of the ultrasonic motor based on the parameters of the input setting module and the pulse signal of the photoelectric encoder transmitted by the interface module; one end of the communication module is connected to the single-chip microcomputer, and the other end is connected to the host computer, and is used to send the ultrasonic motor speed data calculated by the above-mentioned single-chip microcomputer to the host computer.

[0006] Preferably, the input setting module sets initial parameters for the single chip microcomputer, including: interrupt time, timer overflow value and overflow times.

[0007] Preferably, the interface module comprises: a power interface unit, a pulse signal interface unit, and a communication interface unit; the power interface unit is connected to the power module and connected to the positive pole and the ground terminal of the photoelectric encoder power supply; the input end of the pulse signal interface unit is connected to the signal output end of the photoelectric encoder, and the output end is connected to the single-chip microcomputer; the input end of the communication interface unit is connected to the single-chip microcomputer, and the output end is connected to the host computer.

[0008] The present invention provides a speed measuring method of a speed measuring device of an ultrasonic motor, the method comprising the following steps:

[0009] S1: The positive and negative poles of the photoelectric encoder are connected to the power interface unit, and the pulse signal output end of the photoelectric encoder is connected to the pulse signal interface unit;

[0010] S2: Set initialization parameters;

[0011] S3: The single chip microcomputer records the number M of pulse signals output by the photoelectric encoder per unit time;

[0012] S4: The MCU enters the update interrupt, and calculates the total value S per unit time according to the number M of pulse signals output by the photoelectric encoder per unit time in step 3;

[0013] S5: Calculate the speed of the ultrasonic motor according to the total value S per unit time obtained in step S4;

[0014] S6: Transmit the speed data to the host computer through the serial communication module.

[0015] Preferably, the specific calculation method of the total value S per unit time in step S4 is as follows:

[0016]

[0017] Where: C re is the timer overflow value, n is the number of timer overflows. The current pulse count value M is greater than the timer overflow value M re When the pulse number M is reset and the count is restarted, the timer overflows n++; when the pulse signal number M is less than the timer overflow value M re When , the total value S per unit time is the number of pulse signals recorded by the microcontroller.

[0018] Preferably, the timer overflow value in step S4 is specifically as follows:

[0019] In step S3, when the number of pulse signals output by the photoelectric encoder of the single-chip microcomputer per unit time is greater than the maximum value of the timer overflow, the timer enters an update interrupt, the timer overflows n++ times and clears the count value, and restarts counting.

[0020] Preferably, in step S5, the specific calculation method of the ultrasonic motor speed is as follows:

[0021] The speed value of the ultrasonic motor is the count value per unit time divided by the total resolution of the encoder and the time coefficient.

[0022] N=S / R*m

[0023] Where: N is the motor speed value; R is the total resolution of the encoder; m is the time coefficient.

[0024] Beneficial effects of the present invention:

[0025] 1. The present invention measures the speed of the ultrasonic motor based on its transient characteristics. It has high speed measurement accuracy and speed resolution, and the speed measurement accuracy can reach 99.7%. The speed resolution can reach 0.0001RPM (revolutions / minute).

[0026] 2. The algorithm is transformed through the relationship between the number of pulses output by the photoelectric encoder and the timing interrupt time of the microcontroller, so that both high-speed and low-speed algorithms can be met to further improve the speed measurement accuracy of the ultrasonic motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly understand the embodiments of the present invention, the accompanying drawings to be used in the embodiments are described below:

[0028] Figure 1 It is a hardware block diagram of the ultrasonic motor speed measuring device provided by the present invention.

[0029] Figure 2 It is a program flow chart of the ultrasonic motor speed measurement method provided by the present invention. DETAILED DESCRIPTION

[0030] The specific implementation of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] like Figure 1 As shown, the present invention designs an ultrasonic motor speed measuring device, including: a single chip microcomputer, a photoelectric encoder, a power supply module, an input setting module, an interface module, a communication module and a host computer;

[0032] The power module is respectively connected to the single-chip microcomputer, the interface module, the communication module and the speed measurement module, and is used to supply power to other modules; the input setting module is connected to the single-chip microcomputer, and is used to set parameters for the single-chip microcomputer; the output end of the interface module is connected to the single-chip microcomputer, and the input end of the interface module is respectively connected to the A, B, and Z three-phases of the photoelectric encoder, and the interface module is used to transmit the pulse signal of the photoelectric encoder to the single-chip microcomputer; the single-chip microcomputer calculates the speed of the ultrasonic motor based on the parameters of the input setting module and the pulse signal of the photoelectric encoder transmitted by the interface module; one end of the communication module is connected to the single-chip microcomputer, and the other end is connected to the host computer, and is used to send the ultrasonic motor speed data calculated by the above-mentioned single-chip microcomputer to the host computer.

[0033] like Figure 2 As shown, the present invention provides a speed measuring method of an ultrasonic motor speed measuring device, and the program flow chart is as follows:

[0034] Step 1: The speed measuring device starts running;

[0035] Step 2: The program starts initialization;

[0036] Step 3: Input parameter settings;

[0037] Step 4: The speed measurement subroutine starts running;

[0038] Step 5: Determine whether the interrupt is enabled for timer 0. If the interrupt is enabled for timer 0, proceed to the next step; if the interrupt is not enabled for timer 0, enable the interrupt for timer 0. Start and reset timer 0;

[0039] Step 6: Determine whether the pulse number M is greater than or equal to the timer overflow value M re If it is greater than or equal to the timer overflow value, it will enter the update interrupt; if it is less than the timer overflow value, it will directly calculate the speed;

[0040] Step 7: The timer enters the update interrupt;

[0041] Step 8: Timer overflow times n++;

[0042] Step 9: The microcontroller obtains the number of pulses M per unit time and starts calculating the motor speed;

[0043] Step 10: Transmit the measured speed data to the host computer via serial communication;

[0044] Step 11: End the run.

Claims

1. An ultrasonic motor speed measuring device, characterized in that: include: Single chip microcomputer, photoelectric encoder, power module, input setting module, interface module and communication module. The power module is respectively connected to the single-chip microcomputer, the input setting module, the interface module and the communication module, and is used to supply power to other modules; the input setting module is connected to the single-chip microcomputer, and is used to set parameters for the single-chip microcomputer; the interface module is used to transmit the pulse signal of the photoelectric encoder to the single-chip microcomputer; the single-chip microcomputer calculates the speed of the ultrasonic motor based on the parameters of the input setting module and the pulse signal of the photoelectric encoder transmitted by the interface module; the communication module is used to send the ultrasonic motor speed data calculated by the above-mentioned single-chip microcomputer to the host computer.

2. The ultrasonic motor speed measuring device according to claim 1, characterized in that: The input setting module sets initial parameters for the single-chip microcomputer, including: interrupt time, maximum overflow value of the timer and overflow times.

3. The ultrasonic motor speed measuring device according to claim 1, characterized in that: The interface module includes a power interface unit, a pulse signal interface unit, and a communication interface unit; the power interface unit is connected to the power module and is used to supply power to the photoelectric encoder and the single-chip microcomputer; the input end of the pulse signal interface unit is connected to the signal output end of the photoelectric encoder, and the output end is connected to the single-chip microcomputer; The input end of the communication interface unit is connected to the single chip microcomputer, and the output end is connected to the host computer.

4. A speed measuring method of an ultrasonic motor speed measuring device, characterized in that: The steps include: S1: Connect the positive and negative poles of the photoelectric encoder to the power interface unit, and connect the pulse signal output end of the photoelectric encoder to the pulse signal interface unit; S2: Set initialization parameters; S3: The single chip microcomputer records the number M of pulse signals output by the photoelectric encoder per unit time; S4: The microcontroller enters the update interrupt, according to the number of pulse signals M output by the photoelectric encoder per unit time in step S3 to calculate the total value S per unit time; S5: Calculate the speed of the ultrasonic motor according to the total value per unit time obtained in step S4; S6: Transmit the speed data to the host computer through the serial communication module.

5. A speed measuring method of an ultrasonic motor speed measuring device as claimed in claim 4, characterized in that: The specific calculation method of the total value S per unit time in step S4 is as follows: Where: C re is the timer overflow value, n is the number of timer overflows. The current pulse count value M is greater than the timer overflow value M re When the pulse number M is reset and the count is restarted, the timer overflows n++; when the pulse signal number M is less than the timer overflow value M re When , the total value S per unit time is the number of pulse signals recorded by the microcontroller.

6. A speed measuring method for an ultrasonic motor speed measuring device as claimed in claim 4, characterized in that: In step S5, the specific calculation method of the ultrasonic motor speed is as follows: N=S / R*m Where: N is the motor speed value; R is the total resolution of the encoder; m is the time coefficient.

7. A speed measuring method of an ultrasonic motor speed measuring device as claimed in claim 4, characterized in that: This method has high speed measurement accuracy and speed resolution. The speed measurement accuracy can reach 99.7%, and the speed resolution can reach 0.0001RPM (revolutions per minute).

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