TW202317336A - Motor driver with improvement accuracy of measurement and robotic arm thereof - Google Patents

Abstract

The disclosure provides a motor driver with improvement accuracy of measurement and robotic arm thereof. The motor driver measures a motor current to generate a current sensing signal, and corrects the current sensing signal according to a first temperature, a first current offset, a second temperature, and a second current offset for improving the performance of the motor.

Description

Motor drive and its robotic arm to improve measurement accuracy

The present invention relates to a motor driver and its mechanical arm that improve the accuracy of measurement, especially to improve the accuracy of measuring motor current, reduce the torque ripple of the motor, and drive the motor driver and its mechanical arm to reduce the vibration of the motor and the mechanical arm. .

Generally, the motor current and rotation speed are controlled by the motor driver. However, the motor driver is easily affected by temperature, which causes the value or signal generated by the operation of the circuit to deviate. In this way, the motor driver will misjudge the motor current value obtained from the motor detection. After running for a long time, the performance of the motor is getting worse, such as serious vibration.

In view of the above problems, the present invention provides a motor driver. After improving the accuracy of measuring the motor current, it can detect errors in time and dynamically compensate the motor current, and precisely control the motor current to reduce the torque ripple of the motor and reduce the vibration of the motor. .

The object of the present invention is to provide a motor driver and its mechanical arm that improve the accuracy of measurement. After the motor driver improves the accuracy of measuring the motor current, it can detect errors in time and dynamically compensate the motor current, and precisely control the motor current. The vibration of the mechanical arm is reduced.

In order to achieve the purpose of the foregoing invention, the motor driver of the present invention measures a motor flow to generate a current sensing signal, and correct the current sensing signal according to a first temperature, a first current offset, a second temperature and a second current offset.

Alternatively, the motor driver measures the motor current at the first temperature and has the first current offset, and measures the motor current at the second temperature with the second current offset, according to the first temperature, the first current offset The displacement, the second temperature and the second current offset establish a correction straight line to obtain a correction value of the current sensing signal to correct the current sensing signal.

Or, before the motor driver executes the task, it measures the motor current at the first temperature with the first current offset, and measures the motor current with the second current offset at the second temperature, and according to the first A temperature, the first current offset, the second temperature and the second current offset establish a compensation formula. In this way, the motor driver measures the motor current at a third temperature to obtain a current sensing signal when performing a task, calculates a correction value according to the third temperature and the compensation formula, and corrects the current sensing signal according to the correction value.

10: Motor driver

30:Position control module

31: The first operation circuit

32: Position controller

40: Speed control module

41: The second operation circuit

42: Speed controller

50: Current control module

51: Current operation circuit

52: Current controller

53:Temperature sensor

54: Current sensing circuit

541: current sensor

55: Digital to analog conversion circuit

56: Microprocessor

60: motor

70:Speed Calculator

80: Encoder

a: motor current

ADC1: digital to analog conversion circuit

ADC2: digital to analog conversion circuit

ADC3: digital to analog conversion circuit

b: motor current

c: motor current

cmd: current command

Cp: correction value

GND: ground voltage

L56: Calibration straight line

O1: offset

O2: offset

RefV1: reference voltage

RefV2: reference voltage

RefV3: reference voltage

V31: The first computing signal

V32: Position control signal

V41: Second computing signal

V42: Speed control signal

V51: current calculation signal

V52: motor control voltage

V55: Analog signal

V56: Feedback signal

V70: Motor position signal

V80: motor speed signal

Va_T: current sensing signal

Va_T1: current sensing signal

Va_T2: current sensing signal

Va_T3: current sensing signal

Vb_T: current sensing signal

Vc_T: current sensing signal

T: temperature information

T1: temperature information

T2: temperature information

T3: Temperature Information

The first figure is a circuit diagram of an embodiment of correcting temperature effects of the motor driver of the present invention.

The second figure is a circuit diagram of an embodiment of the current control module correcting the temperature effect of the present invention.

The third figure is a flowchart of an embodiment of the present invention for estimating the influence of temperature on a motor driver.

FIG. 4 is a schematic diagram of an embodiment of a calibration straight line of the current control module of the present invention.

The fifth figure is a flow chart of an embodiment of the online temperature correction of the mechanical arm of the present invention.

Relevant present invention is to achieve above-mentioned object, the technical means that adopts and effect thereof, give embodiment hereby, and cooperate drawing to illustrate as follows.

Please refer to the first diagram, which is a circuit diagram of an embodiment of correcting temperature effects of the motor driver of the present invention. As shown in the figure, the motor driver 10 controls the operation of the motor 60, and measures a motor current a to generate a current sensing signal Va_T, but the motor driver 10 will be affected by temperature, and the level of the current sensing signal Va_T is not the actual motor. Current a. Therefore, at different temperatures, such as a first temperature and a second temperature, the motor driver 10 will have a first current offset and a second current offset, and the motor driver 10 of the present invention utilizes the first temperature, the second temperature Two temperature, the first current offset and the second current offset correct the current sensing signal Va_T to obtain the correct motor current a, improve the accuracy of measurement, and can precisely control the motor current a to slow down the vibration of the motor . in this way. When the motor driver 10 of the present invention is applied to a robot arm, it can also reduce the vibration of the robot arm during operation.

The motor driver 10 includes a position control module 30, a speed control module 40 and a current control module 50, the motor driver 10 receives a current command cmd, the position control module 30, the speed control module 40 and the current control module 50 controls the operation of motor 60 according to the current command cmd. The current control module 50 generates a motor control voltage V52 to control the operation of the motor 60 according to the current command cmd. The current control module 50 includes a current controller 52 , a current sensing circuit 54 and a microprocessor 56 . In this way, the current controller 52 outputs the motor control voltage V52 according to the current command cmd at the first temperature to control the operation of the motor 60 to generate the motor current a, and outputs the motor control voltage V52 according to the current command cmd at the second temperature to control the motor 60 running produces motor current a. Wherein, it is assumed that the motor current a generated by the operation of the motor 60 complies with the control of the current command cmd, and there is no obvious deviation.

The current sensing circuit 54 measures the motor current a at the first temperature to generate a current sensing signal Va_T1 at the first temperature (as shown in the third figure), and measures the motor current a at the second temperature to generate Generate a current sensing signal Va_T2 at the second temperature (as shown in FIG. 3 ). The microprocessor 56 calculates the current command cmd and the current sensing signal Va_T1 at the first temperature to generate the first current offset; and calculates the current command cmd and the current sensing signal Va_T2 at the second temperature to generate the second current offset. current offset. In this way, the microprocessor 56 calculates the first current offset and the second current offset according to the current command cmd and the current sensing signal Va_T measured at different temperatures. In another embodiment, a temperature sensor 53 is used to measure the first temperature and the second temperature to generate a first temperature information (such as the third figure) and a second temperature information (such as the third figure), so the microprocessor The device 56 stores the first current offset and the second current offset at different temperatures, and stores the first temperature information T1 and the second temperature information T2 at different temperatures.

Therefore, the motor driver 10 has a first current offset when measuring the motor current a at the first temperature, and has a second current offset when measuring the motor current a at the second temperature, and according to the first temperature, the first current The offset, the second temperature, and the second current offset establish a compensation calculation formula, and a correction value Cp of the current sensing signal Va_T can be obtained according to the compensation calculation formula. In other words, the microprocessor 56 uses the stored first current offset, the second current offset, the first temperature information T1 and the second temperature information T2 to establish a compensation calculation formula to calculate the correction of the current sensing signal Va_T Value Cp. In this way, the accuracy of measuring the motor current a is improved by the correction value Cp, and the corrected current sensing signal Va_T can enable the motor driver 10 to detect errors in time and dynamically compensate the motor current a, so as to accurately control the motor current a to reach the motor current a. 60 with reduced vibration of the mechanical arm.

Referring back to FIG. 1 , the current control module 50 of the motor driver 10 includes a digital-to-analog conversion circuit 55 coupled to the current sensing circuit 54 to convert the current sensing signal Va_T into an analog signal V55 . The microprocessor 56 is coupled to the digital-to-analog conversion circuit 55 to receive the analog signal V55 to generate a feedback signal V56. A current operation circuit 51 receives the feedback signal V56 and a speed control signal signal V42 to generate a current calculation signal V51. In this way, the current controller 52 generates the motor control voltage V52 according to the current calculation signal V51, and can adjust the motor current a according to the highly accurate feedback signal V56 (current sensing signal Va_T). In addition, there is a feedback loop between the motor 60 and the current computing circuit 51, and the signals therein can be regarded as feedback signals.

The motor driver 10 includes an encoder 70 and a speed calculator 80 . The encoder 70 detects a motor rotation position of the motor 60 to generate a motor position signal V70. The speed calculator 80 is coupled to the encoder 70 to generate a motor speed signal V80 according to the motor position signal V70. The position control module 30 includes a first calculation circuit 31 and a position controller 32. The first calculation circuit 31 receives the current command cmd and the motor position signal V70 to generate a first calculation signal V31. The position controller 32 generates a first calculation signal V31 according to the first calculation The signal V31 generates a position control signal V32. The speed control module 40 includes a second computing circuit 41 and a speed controller 42. The second computing circuit 41 receives the position control signal V32 and the motor speed signal V80 to generate a second computing signal V41. The speed controller 40 generates a second computing signal V41 according to the second The calculation signal V41 generates a speed control signal V42.

Therefore, the motor driver 10 establishes a compensation calculation formula according to the first temperature, the first current offset, the second temperature, and the second current offset before driving to perform a task, and the motor driver 10 measures a first when driving to perform a task. The current sensing signal Va_T3 is obtained from the motor current a at the three temperatures, and another correction value Cp is calculated according to the third temperature and the compensation formula, and the current sensing signal Va_T3 is corrected according to the correction value Cp. Wherein, the first temperature is different from the second temperature, but it is not limited whether the third temperature is the same as the first temperature and the second temperature. In addition, if the motor driver 10 calibrates the current sensing signal Va_T1 measured at the first temperature before delivery, the motor driver 10 does not have the first current offset, that is, the first current offset is 0.

Please refer to the second figure, which is one of the correction temperature effects of the current control module of the present invention Example circuit diagram. As shown in the figure, the motor driver 10 is provided with a plurality of current sensing circuits 54 for detecting the complex motor currents a, b, and c, and these current sensing circuits 54 respectively include a current sensor 541 and a plurality of impedance elements, so as to After the motor currents a, b, and c are respectively detected, current sensing signals Va_T, Vb_T, Vc_T are respectively generated to the ADC circuit 55 . Furthermore, the current sensors 541 of the current sensing circuits 54 are respectively coupled to the reference voltages Ref V1, Rer V2, Rer V3 for operation, and the three reference voltages Ref V1, Rer V2, Rer V2, Rer V3 can be the same or different from each other, which is a design option. Therefore, the embodiment in the second figure includes a plurality of ADC circuits 55 , such as ADC1 , ADC2 , and ADC3 , which are respectively coupled to three current sensing circuits 54 from top to bottom in the second figure. Moreover, the ADC1 circuit, the ADC2 circuit and the ADC3 circuit are arranged in the microprocessor 56, or can be arranged outside the microprocessor 56 as in the embodiment of the first figure, which are all design options, and the implementation of the present invention is not limited.

Furthermore, the temperature sensor 53 can also be optionally installed in the current control module 50 to measure the ambient temperature, such as the first temperature, the second temperature, and the third temperature. The ambient temperature can include the temperature generated by the operation of the motor driver 10 itself. temperature plus the overall temperature of the surrounding area. The temperature sensor 53 generates temperature information T after measuring the ambient temperature. The temperature information of the first temperature is T1 (as shown in the third figure), the temperature information of the second temperature is T2 (as shown in the third figure), and the temperature information of the third temperature is T2 (as shown in the third figure). The information is T3 (as shown in the fifth picture). Moreover, the current sensing signals Va_T, Vb_T, and Vc_T may also be affected by temperature changes, and cannot represent the correct motor currents a, b, and c. In this way, after the microprocessor 56 establishes the compensation formula according to the stored information, it can generate respective correction values Cp to correct the current sensing signals Va_T, Vb_T, Vc_T, and generate respective feedback signals V56.

Please refer to FIG. 3 , which is a flow chart of an embodiment of the present invention for estimating the influence of temperature on the motor driver. As shown in the figure, it is first estimated that the motor driver 10 is driven to perform tasks The current offset affected by temperature, and the motor driver 10 can be applied to the robot arm, in other words, estimate the current offset affected by the temperature before the robot performs tasks (such as welding, picking and placing workpieces or other collaborative tasks). When the motor driver 10 (or the robot arm) is first started, the ambient temperature should be low temperature or room temperature, that is, start step S11, the low (room) temperature (eg first temperature) offset estimation procedure. Step S12 , a controller is coupled to the motor driver 10 and outputs a current command cmd to the motor driver 10 to control the operation of the motor 60 . In step S13 , the current sensing circuit of the motor driver 10 measures the motor current a to generate a current sensing signal Va_T1 at low (room) temperature. Wherein, the motor 60 has three-phase motor currents a, b, and c, but the embodiment is usually described with one motor current a. In step S14 , the motor driver 10 (or the microprocessor 56 ) calculates the current offset (such as the first current offset) O1=cmd−Va_T1 of the current sensing signal Va_T1 at low (room) temperature. In step S15 , the temperature sensor 53 measures the temperature of the environment to generate temperature information T1 , that is, temperature information T1 of the first temperature. In step S16 , the motor driver 10 (or the microprocessor 56 ) stores the estimated current offset O1 and the measured temperature information T1 at the low (room) temperature.

Furthermore, the temperature of the motor driver 10 (or the mechanical arm) rises gradually after working for a period of time, which is the second temperature. In step S21, the high temperature offset estimation procedure is started. In step S22 , the controller also outputs the current command cmd to the motor driver 10 to control the operation of the motor 60 . However, it is not limited whether the current command cmd at the second temperature is the same as the current command cmd at the first temperature. In step S23 , the current sensing circuit 54 measures the motor current a to generate a current sensing signal Va_T2 at a high temperature (such as a second temperature). In step S24 , the microprocessor 56 calculates a current offset (such as a second current offset) O2 = cmd - Va_T2 of the current sensing signal Va_T2 at high temperature. In step S25 , the temperature sensor 53 measures the temperature of the environment to generate temperature information T2 , that is, temperature information T2 of the second temperature. In step S26 , the microprocessor 56 stores the estimated current offset O2 and the measured temperature information T2 at high temperature.

Figure 4 is a schematic diagram of an embodiment of the calibration straight line of the current control module of the present invention. The information stored in the motor driver 10 can establish a compensation calculation formula, and draw the first intersection point (O1, T1) and the second intersection point (O2, T2) to establish a correction line L56, and correct the current inductance according to the correction line L56 Test signal Va_T. However, when the manipulator is calibrated before leaving the factory, there is no first current offset O1, so the first intersection point can be changed to (0, T1), while the second intersection point remains unchanged, but the slope of the calibration line L55 is different . Wherein, the X-axis is the temperature information T related to the temperature, and the Y-axis is the current offset, so the Y-axis shows the compensation value required by the current sensing signal Va_T, which can also be called the correction value Cp. In other words, after the mechanical arm stores the relevant information of the calibration line L55, it starts to execute the task, that is, at the third temperature that is the same as or different from the first temperature or the second temperature, it can use the method of query, according to the third temperature (X axis) Correspondingly detect the current offset (Y axis) to correct the current sensing signal Va_T. In this way, the manipulator can choose not to calculate the correction value Cp through the compensation calculation formula during operation, which can also improve the accuracy of measuring the motor current a. In addition, the computation of the compensation formula is not limited to be performed by the microprocessor 56, and other computing capabilities (such as controllers) with matching capabilities can also handle the same computation.

Please refer to FIG. 5 , which is a flow chart of an embodiment of the online temperature correction of the mechanical arm of the present invention. As shown in the figure, in addition to querying the correction value Cp at different temperatures according to the correction line L56 in the embodiment in the fourth figure, the embodiment in the fifth figure can be used to obtain the correction value Cp through the compensation formula. The online calibration procedure starts in step S31, that is, the calibration is also performed while the mechanical arm (motor driver 10) is operating. The compensation calculation formula can be established and stored as described above, or as in step S32, read relevant information when needed, that is, read the current offset O1 and temperature information T1 of the low (room) temperature, and read the high temperature Current offset O2, temperature information T2. In step S33, according to the previously read information, a compensation formula for the current sensing module 50 in the robotic arm is established, which is Y=((O2-O1)/(T2-T1))*X+((O1T2-O2T1)/(T2-T1)). In step S34, the temperature sensor 53 in the robot arm measures the ambient temperature to generate temperature information T3 related to the third temperature. In step S35, bring the temperature information T3 into the above-mentioned compensation formula, which is Cp=((O2-O1)/(T2-T1))*T3+((O1T2-O2T1)/(T2-T1)), and obtain Correction value Cp. In step S36 , the current sensing module 50 measures the motor current a to generate a current sensing signal Va_T3 , and the current sensing signal at this time is measured at the third temperature, so it is marked as Va_T3 . In step S37, the current sensing signal Va_T3 at the third temperature is compensated, that is, the current sensing signal Va_T3 minus the temperature-affected current offset (such as the correction value Cp) is Va=Va_T3-Cp, and the actual The motor current a, that is, the effect of reducing the ambient temperature. In addition, the embodiment in the fifth figure is to establish the compensation calculation formula first, and then measure the temperature information T3 of the environment, but the implementation method can be changed to first measure the temperature information T3 of the environment, and then establish the compensation calculation formula, which is adjustable in the embodiment choice.

To sum up, the motor driver of the present invention measures a motor current to generate a current sensing signal, and corrects it according to a first temperature, a first current offset, a second temperature, and a second current offset current sense signal.

Alternatively, the motor driver measures the motor current at the first temperature and has the first current offset, and measures the motor current at the second temperature with the second current offset, according to the first temperature, the first current offset The displacement, the second temperature and the second current offset establish a correction straight line to obtain a correction value of the current sensing signal to correct the current sensing signal.

Or, before the motor driver executes the task, it measures the motor current at the first temperature with the first current offset, and measures the motor current with the second current offset at the second temperature, and according to the first A temperature, the first current offset, the second temperature and the second current offset establish a compensation formula. In this way, the motor driver measures the temperature at a third temperature when performing a task The motor current is used to obtain the current sensing signal, and the correction value is calculated according to the third temperature and the compensation calculation formula, and the current sensing signal is corrected according to the correction value.

Both of the above two implementations can detect errors in time and dynamically compensate the motor current, and precisely control the motor current to reduce the vibration of the motor. Moreover, the application to the mechanical arm can also reduce the vibration phenomenon of the arm.

The above-mentioned ones are only used to illustrate the embodiments of the present invention for convenience. The scope of the present invention is not limited to these embodiments. The scope of patent applications for inventions.

53:Temperature sensor

54: Current sensing circuit

541: current sensor

55: Digital to analog conversion circuit

56: Microprocessor

60: motor

a: motor current

ADC1: digital to analog conversion circuit

ADC2: digital to analog conversion circuit

ADC3: digital to analog conversion circuit

b: motor current

c: motor current

GND: ground voltage

RefV1: reference voltage

RefV2: reference voltage

RefV3: reference voltage

Va_T: current sensing signal

Vb_T: current sensing signal

Vc_T: current sensing signal

T: temperature information

Claims (9)

A mechanical arm, which includes a motor driver to measure a motor current to generate a current sensing signal, and according to a first temperature, a first current offset, a second temperature and a second current offset, Calibrate the current sense signal. The mechanical arm described in item 1 of the scope of the patent application, wherein the motor driver measures the motor current at the first temperature with the first current offset, and measures the motor current at the second temperature with the The second current offset is based on the first temperature, the first current offset, the second temperature and the second current offset to establish a compensation calculation formula, and the current sensing is obtained according to the compensation calculation formula A calibration value of the signal. The mechanical arm described in item 1 of the scope of the patent application, wherein the motor driver establishes a calibration line based on the first temperature, the first current offset, the second temperature, and the second current offset, according to The calibration straight line corrects the current sensing signal. The mechanical arm described in item 1 of the scope of the patent application, wherein the motor driver establishes a function according to the first temperature, the first current offset, the second temperature and the second current offset before performing the task. A compensation calculation formula, the motor driver measures the motor current at a third temperature to obtain the current sensing signal when performing a task, calculates a correction value based on the third temperature and the compensation calculation formula, and calculates a correction value based on the correction value Calibrate the current sense signal. The robotic arm described in item 1 of the scope of the patent application includes: a current controller, outputting a motor control voltage according to a current command at the first temperature to control the motor current; a current sensing circuit measuring the motor current to generate the current sensing signal at the first temperature; and A microprocessor calculates the current command and the current sensing signal to generate the first current offset. The mechanical arm described in item 5 of the scope of the patent application, wherein the current controller outputs the motor control voltage according to the current command at the second temperature to control the motor current, and the current sensing circuit measures the motor The current is used to generate the current sensing signal at the second temperature, and the microprocessor calculates the current command and the current sensing signal to generate the second current offset. The robotic arm described in item 6 of the scope of the patent application includes: a temperature sensor for measuring the first temperature and the second temperature to generate a first temperature information and a second temperature information; Wherein, the motor driver stores the first temperature information, the second temperature information, the first current offset and the second current offset. The robotic arm described in item 7 of the scope of the patent application includes: A digital-to-analog conversion circuit, coupled to the current sensing circuit, converts the current sensing signal into an analog signal; The microprocessor calculates the first current offset and the second current offset according to the current command and the current sensing signals measured at different temperatures, and stores the first temperature information and the second current offset. 2 temperature information, and store the first current offset and the second current offset to generate a correction value to correct the current sensing signal at a third temperature, and generate a feedback signal; A current calculation circuit, receiving the feedback signal and a speed control signal to generate a current calculation signal; and The current controller generates the motor control voltage according to the current operation signal to adjust the motor current. The robotic arm described in item 8 of the scope of the patent application includes: An encoder, which detects the rotational position of a motor and generates a motor position signal; A speed calculator, coupled to the encoder, generates a motor speed signal according to the motor position signal; A position control module, including a first computing circuit and a position controller, the first computing circuit receives the current command and the motor position signal to generate a first computing signal, the position controller according to the first computing signal generating a position control signal; and A speed control module, including a second computing circuit and a speed controller, the second computing circuit receives the position control signal and the motor speed signal to generate a second computing signal, the speed controller according to the second computing signal to generate the speed control signal.

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