JP2021087223A - Servo device using estimated angular speed by motor torque - Google Patents

Abstract

To provide a servo device capable of reducing vibration without using an expensive angle detector.SOLUTION: A servo device of the invention controls a gimbal device 200 which comprises a first angle detector 13 driven by a first motor 15 and detecting a rotation angle of an AZ flame 11 rotated about an AZ axis 12, and a first motor characteristic detector 17 detecting motor characteristics in response to a rotating torque of the first motor 15. A first angular speed estimator 43 is provided to calculate a control angular speed respectively from a differential angular speed calculated by differentiating an output from the first angle detector 13 and an integral angular speed calculated by integrating an output from the first motor characteristic detector 17.SELECTED DRAWING: Figure 2

Description

The present invention relates to a servo device, and more particularly to a servo device used for controlling a gimbal device that adjusts the orientation while holding a camera, for example.

Conventionally, the gimbal device 200 shown in FIG. 1 has been used as a device for freely following the direction of the camera toward the target. The gimbal device 200 includes two orthogonal axes, a two-axis AZ provided with an AZ axis 12 and an EL axis 22, and EL frames 11 and 21. Inside the one AZ frame 11, an EL frame 21 provided with a camera 30 is provided. In both frames 11, 21, the first and second motors 15, 25, and the first and second angle detectors 13 are used to rotate each frame 11, 21 by a finite angle and to detect an angle. , 23 are provided respectively. The first and second motors 15 and 25 and the first and second angle detectors 13 and 23 are motor resolvers of the first and second motors 15 and 25 and the resolver arranged coaxially with each other, or the first. It is configured as a motor encoder of the first and second motors 15 and 25 and an encoder, respectively. The camera 30 is controlled by the servo device 40 shown in FIG. 4 with the outputs of the first and second angle detectors 13 and 23 and the operation signal. Each detection angle output from the first and second angle detectors 13 and 23 is differentiated by the angular velocity calculators 55 and 56 provided in the servo device 40, and the control angular velocity is calculated. FIG. 5 shows the outputs of the angle detectors 13 and 23 of the gimbal device 200 in the stopped state.

Japanese Patent Application Laid-Open No. 2000-39486

However, as shown in FIG. 5, the output values of the angle detectors 13 and 23 fluctuate by one resolution even when the gimbal device 200 is stopped. When the outputs from the angle detectors 13 and 23 are differentiated in order to calculate the control angular velocity, the signal including the fluctuation of one resolution is differentiated and becomes a large value of the angular velocity, which becomes noise. FIG. 6 shows the calculated angular velocities when the outputs of the angle detectors 13 and 23 shown in FIG. 5 are differentiated. Due to the noise included in the calculated angular velocity, the gimbal device 200 moves in small steps even though the first and second motors 15 and 25 of the gimbal device 200 are actually stopped. As a result, small movements of the camera 30 fixed to the gimbal device 200, so-called picking, occur. As a method of reducing the picking of the gimbal device 200, there is a method of using angle detectors with high accuracy, that is, high resolution, for the first and second angle detectors 13 and 23 of the gimbal device 200. However, a high-precision angle detector has a drawback of being expensive.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a servo device capable of reducing picking without using an expensive angle detector.

The servo device according to the present invention includes an angle detector that detects the rotation angle of a frame that is driven by a motor and rotates about an axis, and a two-motor characteristic detector that detects motor characteristics according to the rotation torque of the motor. A servo device that controls a gimbal device equipped with, and is a controlled angular velocity from the differential angular velocity calculated by differentiating the output from the angle detector and the integrated angular velocity calculated by integrating the output from the motor characteristic detector. An angular velocity estimator is provided to calculate.

Further, in the servo device according to the present invention, the angular velocity estimator may add the differential angular velocity and the integrated angular velocity by weighting each according to the frequency domain.

Further, in the servo device according to the present invention, the ratio of the differential angular velocity is made larger on the lower frequency side than the ratio of the integrated angular velocity in the low frequency region with the reference frequency at which the differential angular velocity and the integrated angular velocity are summed at the same ratio as a boundary. In the high frequency region, the ratio of the integrated angular velocity may be increased toward the higher frequency side than the ratio of the differential angular velocity and summed.

Further, in the servo device according to the present invention, the motor characteristic detector may be a current sensor that detects the driving current of the motor.

The servo device according to the present invention is an angular velocity estimator that calculates the control angular velocity from the differential angular velocity calculated by differentiating the output from the angle detector and the integrated angular velocity calculated by integrating the output from the motor characteristic detector. Since it has, it is possible to reduce the influence of high frequency noise associated with differentiating the output from the angle detector.

In the angular velocity estimator in the servo device according to the present invention, the differential angular velocity and the integrated angular velocity are weighted and summed according to the frequency domain, so that a useful controlled angular velocity can be obtained according to the frequency.

In the servo device according to the present invention, the weighting increases the ratio of the differential angular velocity toward the low frequency side in the low frequency region with the reference frequency at which the differential angular velocity and the integrated angular velocity are summed at the same ratio as the boundary, and in the high frequency region. Since the ratio of the integrated angular velocity is increased toward the high frequency side, the optimum control angular velocity can be calculated for each system.

Since the motor characteristic detector in the servo device according to the present invention uses a current sensor that detects the drive current of the motor, the motor characteristic detector can also be used as a current sensor for monitoring the overcurrent of the motor, and is a low-cost and compact servo device. Can be.

It is a side view which provided the servo device which concerns on embodiment of this invention, and showed the space stabilizer for explaining the conventional structure. It is a block diagram which showed the control of the servo device which concerns on embodiment of this invention. It is a control characteristic diagram which showed the control of the servo device of FIG. It is a block diagram which showed the control of the conventional servo device. It is a characteristic diagram which showed the angle output of the angle detector in the servo device of FIG. It is a characteristic diagram which showed the angular velocity obtained by calculating the angular output of the angle detector in the servo device of FIG.

<Embodiment>
Hereinafter, the servo device 40 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 3. The same or equivalent parts as those of the conventional example will be described using the same reference numerals.

FIG. 1 is a side view showing the gimbal device 200 according to the embodiment of the present invention. Further, FIG. 2 is a block diagram showing control of the servo device 40 according to the embodiment of the present invention. Further, FIG. 3 is a control characteristic diagram showing the control characteristics of the servo device 40.

The gimbal device 200 has a base 10 having an AZ axis 12, a square frame-shaped AZ frame 11 rotatably held by the AZ axis 12, and a finite operation for rotating the AZ frame 11 via the AZ axis 12. The first motor 15 and the first angle detector 13 at the corner, the square frame-shaped EL frame 21 having the EL shaft 22 penetrating the two opposing sides, and the camera 30 provided on the front side of the EL frame 21. A servo device 40 that controls the gimbal angle according to an operation signal, a second motor 25 for rotating the EL frame 21 together with the camera 30, and a second angle detection for detecting the rotation angle of the second motor 25. It is equipped with a vessel 23.

The base 10 is a member that holds the gimbal device 200. The base 10 is fixed to, for example, a building, a vehicle, an aircraft, or the like to which a camera or the like is fixed.

The base 10 includes an AZ axis 12 that rotatably holds the AZ frame 11, a first angle detector 13 that detects the rotation angle of the AZ frame 11 with respect to the base 10 around the AZ axis 12, and an AZ frame. It has a first motor 15 for rotating 11, a first drive circuit (not shown) for driving the first motor 15, and a first motor characteristic detector 17 for detecting an operating state of the first motor 15.

As described above, the AZ frame 11 is a hollow member formed in a square frame shape. It is rotatably held by the AZ axis 12 of the base 10 via a first motor 15 on one of the two sides of the corresponding set and a first angle detector 13 on the other. Inside the AZ frame 11, the first motor 15 and the first angle detector 13 are provided on one of the other opposing sets of sides, which is not the opposite set of sides. A second angle detector 23 is provided on either side of the second motor 25. An EL shaft 12 is inserted into the center of the second motor 25 and the center of the second angle detector 23, and the EL frame 21 is rotatably held in a state different from the AZ frame 11 by 90 °. ing. Further, the EL frame 21 is provided with a second drive circuit (not shown) for driving the second motor 25 and a second motor characteristic detector 27 for detecting the operating state of the second motor 25.

The AZ axis 12 that rotatably holds the AZ frame 11 is arranged so as to be perpendicular to the ground, for example. Further, the EL shaft 12 that rotatably holds the EL frame 21 is arranged so as to form a right angle to the AZ shaft 12. The EL frame 21 is a member whose orientation is controlled by the gimbal device 200, and is provided with, for example, a camera 30.

The first motor characteristic detector 17 and the second motor characteristic detector 27 are detectors that detect the operating states of the first motor 15 and the second motor 25, respectively. The first motor characteristic detector 17 and the second motor characteristic detector 27 are, for example, a first current sensor 17A and a second current sensor 27A that detect the drive currents of the first motor 15 and the second motor 25 in operation, respectively. It is configured.

Alternatively, the first motor characteristic detector 17 and the second motor characteristic detector 27 may be a first torque sensor 17B and a second torque sensor 27B that detect the rotational torque of the motor, respectively. Alternatively, one of the first motor characteristic detector 17 and the second motor characteristic detector 27 may be a current sensor and any other may be a torque sensor.

Next, in the servo device 40 according to the present invention, the first and second angle controllers 41 and 45 and the first and second angle controllers 41, in which the angle command θcom is input via the first subtractors 51 and 53, The first and second angular velocity controllers 42, 46 in which 45 is connected via the second subtractors 52, 54, and the first and second angular velocity estimators 43 connected to the second subtractors 52, 54. , 47, and is configured as shown in FIG. When there are a plurality of rotating systems that are pivotally supported and rotate as in the present embodiment, the control angles of each rotating system can be calculated. For example, the rotating system that rotates the AZ frame 11 with respect to the base 10 has a first angle controller 41, a first angular velocity controller 42, and a first angular velocity estimator 43. Further, the rotating system for rotating the EL frame 21 includes a second angular velocity controller 45, a second angular velocity controller 46, and a second angular velocity estimator 47. Specifically, one servo device 40 includes angle controllers 41 and 45, angular velocity controllers 42 and 46, and angular velocity estimators 43 and 47, which control each rotating system, respectively. ing. Alternatively, two sets of servo devices including one set of an angle controller, an angular velocity controller, and an angular velocity estimator may be provided.

As described above, in the present embodiment, the first and second angle detectors 13, 23, the first and second motor characteristic detectors 17, 27, the first and second angle controllers 41, 45, first and The second angular velocity controllers 42 and 46, and the first and second angular velocity estimators 43 and 47 are provided in each rotating system, respectively, and a total of two sets are provided. Since each rotating system is provided with the same functional one, in the following description, the rotating system for rotating the AZ frame 11 with respect to the base 10 and the corresponding first angle controller 41 will be described. The servo device 40 having the first angular velocity controller 42 and the first angular velocity estimator 43 will be described. The rotating system that rotates the EL frame 21 with respect to the AZ frame 11, the corresponding second angle controller 45, the second angular velocity controller 46, and the second angular velocity estimator 47 also function in the same manner. It is configured to do. In other words, the second angle controller 45 has the same functions as the first angle controller 41, the second angular velocity controller 46 has the same functions as the first angular velocity controller 42, and the second angular velocity estimator 47 has the same functions as the first angular velocity estimator 43. doing.

The output of the first angle detector 13 is input to the angular velocity estimator 43 and differentiated to calculate the angular velocity. Further, the output of the first motor characteristic detector 17 is input to the angular velocity estimator 43 and integrated to calculate the angular velocity. The angular velocity obtained by differentiating the angular output of the first angle detector 13, that is, the differential angular velocity and the angular velocity obtained by integrating the output of the first motor characteristic detector 17, that is, the integrated angular velocity are the angular velocity estimators. Total within 43.

The motor torque and the motor drive current have a proportional relationship, and they and the angular acceleration have the following relationship.

According to the above equation, if the motor torque is detected by the torque sensor or the motor drive current is detected by the current sensor, the angular acceleration can be calculated by the above equations 1 and 2. In addition, in order to control the current of the motor, a current sensor may be provided in the first drive circuit 16 which is a motor drive circuit. In that case, since the current sensor for the present invention can also be used as a current sensor for overcurrent monitoring, it is not necessary to newly provide a current sensor.

Here, the difference between the differential angular velocity obtained by differentiating the angular output of the first angle detector 13 and the integrated angular velocity obtained by integrating the output of the first motor characteristic detector 17 will be described. FIG. 3 shows a conceptual diagram of the angle estimator 43 that sums the differential angular velocity and the integrated angular velocity. First, the differential angular velocity obtained by differentiating the angular output from the first angle detector 13 includes high-frequency noise associated with differentiating a value within one resolution. On the other hand, the integrated angular velocity obtained by integrating the motor characteristic output from the first motor characteristic detector 17 does not include high-frequency noise due to differentiation, but may include errors such as drift and low-frequency noise. is there. From the above, the differential angular velocity has a low noise region in the low frequency region, and the integrated angular velocity has a low noise region in the high frequency region. The present invention makes use of this point. By combining the calculated differential angular velocity and the integrated angular velocity, each defect is canceled. That is, the differential angular velocity by differentiating the angular output from the first angle detector 13 and the integrated angular velocity by integrating the output of the first motor characteristic detector 17 are calculated, and the total value thereof is calculated according to the frequency. By using a useful area, it is possible to reduce the picking when the gimbal device is stopped.

In FIG. 3, the frequency at the point where the line A showing the gain with respect to the frequency of the differential angular velocity and the line B showing the gain with respect to the frequency of the integrated angular velocity intersect is defined as the reference frequency C. At this reference frequency C, the differential angular velocity and the integrated angular velocity are summed at the same ratio. In the frequency region lower than the reference frequency C, the ratio of the differential acceleration obtained by differentiating the output from the first angle detector 13 and the ratio of the integrated acceleration obtained by integrating the output from the first motor characteristic detector 17 Gradually increase the lower frequency side and add up. Further, in the high frequency region, the ratio of the integrated acceleration obtained by integrating the output from the first motor characteristic detector 17 is on the higher frequency side than the ratio of the differential acceleration obtained by differentiating the output from the first angle detector 13. Gradually increase and add up.

The reference frequency C is configured to be adjustable according to the system. The reference frequency C is, for example, 10 Hz.

As described above, even when there are a plurality of rotating systems, the effect of the present invention can be obtained in each rotating system by controlling each rotating system in the same manner as described above.

The servo device 40 according to the embodiment of the present invention is driven by the first motor 15, and is driven by the first angle detector 13 that detects the rotation angle of a member that rotates about the first axis 12, and responds to the rotation torque of the motor. The differential angular velocity calculated by controlling the gimbal device including the first motor characteristic detector 17 for detecting the motor characteristic value and differentiating the output from the first angle detector 13 and the first motor characteristic detector. The control angular velocity is calculated from the integrated angular velocity calculated by integrating the outputs of.

Therefore, the servo device 40 according to the present invention can reduce the influence of the differential noise included in the control angular velocity obtained by differentiating the angle detector output, so that the picking of the gimbal device can be reduced.

10 base, 11 AZ frame, 12 AZ axis, 13 1st angle detector, 15 1st motor, 17 1st motor characteristic detector, 17A 1st current sensor, 21 EL frame, 22 EL axis, 23 2nd angle Detector, 25 2nd motor, 27 2nd motor characteristic detector, 27A 2nd current sensor, 43 1st angular velocity estimator, 47 2nd angular velocity estimator, 200 gimbal device

Claims (4)

A first angle detector (13) that detects the rotation angle of the AZ frame (11) that is driven by the first motor (15) and rotates about the AZ axis (12).
A second angle detector (23) that detects the rotation angle of the EL frame (21) that is driven by the second motor (25) and rotates about the EL axis (22).
A gimbal device (200) including first and second motor characteristic detectors (17, 27) that detect motor characteristics according to rotational torque of the first and second motors (15, 25), respectively, is controlled. It ’s a servo device,
Calculated by integrating the differential angular velocity calculated by differentiating the output from the first or second angle detector (13, 23) and the output from the first or second motor characteristic detector (17, 27). The angular velocity estimators (43, 47) that calculate the control angular velocity based on the integrated angular velocity are used for controlling the rotating system of the AZ axis (12) and for controlling the rotating system of the EL axis (22). A servo device provided in at least one of the above. The servo device according to claim 1, wherein the angular velocity estimator (43, 47) totals the differential angular velocity and the integrated angular velocity by weighting each of them according to a frequency domain. With the reference frequency at which the differential angular velocity and the integrated angular velocity are summed at the same ratio as a boundary, the ratio of the differential angular velocity is larger on the lower frequency side than the ratio of the integrated angular velocity in the low frequency region, and the integrated angular velocity in the high frequency region. The servo device according to claim 1 or 2, wherein the ratio of is larger on the high frequency side than the ratio of the differential angular velocity. The first and second motor characteristic detectors (17, 27) are current sensors (17A, 27A) that detect the drive currents of the first and second motors (15, 25), claims 1 to 3. The servo device according to any one of the above.

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