JP2020096481A - Electric motor control device and control method, and object detection device - Google Patents

Abstract

To change the change amount of a rotation angle per unit time in a desired rotation angle or a desired rotation angle range in one rotation cycle of an electric motor.SOLUTION: A control device 100 of an electric motor 20 includes a rotation angle detection unit 12 that detects the rotation angle of the electric motor 20, and a control unit 10 that controls the amount of change in the rotation angle of the electric motor 20 per unit time according to the rotation angle detected by the rotation angle detection unit 12. The control unit 10 makes the amount of change in a first rotation angle range different from the amount of change in a second rotation angle range other than the first rotation angle range in one rotation cycle of the electric motor 20.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an electric motor control device and control method, and an object detection device including the electric motor control device.

There has been proposed a speed control device for controlling a motor at a constant speed in an optical deflector having a polygon mirror at one end of the motor (for example, Patent Document 1).

JP-A-7-105249

However, for example, in a distance measuring device that measures a distance by rotating a polyhedron with an electric motor, when the electric motor is rotationally driven at a constant speed, the absolute distance measuring accuracy at a desired rotation angle, that is, the SN ratio is improved. Can't plan. Further, in an apparatus in which a rotating body is rotationally driven by an electric motor to execute various kinds of processing, processing accuracy for a desired rotation angle or a desired rotation angle range cannot be improved more than processing accuracy for other rotation angles or rotation angle ranges. ..

Therefore, it is required to change the change amount of the rotation angle per unit time in a desired rotation angle or a desired rotation angle range in one rotation cycle of the electric motor.

The present disclosure can be implemented as the following aspects.

The first aspect provides a control device for an electric motor. A motor control device according to a first aspect includes a rotation angle detection unit that detects a rotation angle of the electric motor, and a rotation angle per unit time of the electric motor according to the rotation angle detected by the rotation angle detection unit. In the one rotation cycle of the electric motor, the change amount in the first rotation angle range is changed in the second rotation angle range other than the first rotation angle range. And a control unit for changing the amount.

According to the motor control device of the first aspect, it is possible to change the amount of change in the rotation angle per unit time in a desired rotation angle or a desired rotation angle range in one rotation cycle of the motor.

The second aspect provides a method for controlling an electric motor. A method for controlling an electric motor according to a second aspect detects a rotation angle of the electric motor and, in one rotation cycle of the electric motor, detects the rotation angle of the electric motor in a first rotation angle range in accordance with the detected rotation angle. The amount of change in the rotation angle per unit time is made different from the amount of change in the second rotation angle range other than the first rotation angle range.

According to the electric motor control method of the second aspect, the change amount of the rotation angle per unit time in the desired rotation angle or the desired rotation angle range can be changed in one rotation cycle of the electric motor. The present disclosure can also be realized as a control method program for an electric motor or a computer-readable recording medium that records the program.

FIG. 3 is an explanatory diagram showing an example of an electric motor control device and an object detection device according to the first embodiment. The flowchart which shows the process flow of the rotation angle control process of the electric motor performed by the control device of the electric motor which concerns on 1st Embodiment. Explanatory drawing which shows the relationship between the rotation speed command value and the azimuth angle of an electric motor in 1st Embodiment. FIG. 3 is an explanatory diagram showing S/N characteristics realized by the motor control device according to the first embodiment. The flowchart which shows the process flow of the rotation angle control process of the other electric motor performed by the control device of the electric motor which concerns on 1st Embodiment. Explanatory drawing which shows an example of the rotation speed command value output from the control apparatus of the electric motor which concerns on 1st Embodiment. Explanatory drawing which shows an example of the rotation speed command value output from the control apparatus of the electric motor which concerns on 1st Embodiment. Explanatory drawing which shows an example of the rotation speed command value output from the control apparatus of the electric motor which concerns on 1st Embodiment. Explanatory drawing which shows the azimuth angle command value in 2nd Embodiment and the conventional azimuth angle command value in contrast. Explanatory drawing which shows the relationship between the light emission timing and azimuth as a comparative example. Explanatory drawing which shows the relationship between the light emission timing and azimuth angle in 3rd Embodiment. Explanatory drawing which shows the relationship between the azimuth angle position command value and time in 4th Embodiment.

An electric motor control device, a control method, and an object detection device according to the present disclosure will be described below based on some embodiments.

First embodiment:
As shown in FIG. 1, the electric motor control device 100 according to the first embodiment is used by being mounted on an object detection device 300 as an example. The control device 100 may include at least the control unit 10 and the rotation angle sensor 12. The object detection device 300 is, for example, Lidar (Light Detection and Ranging), and includes an electric motor 20, an electric motor driver 21, a light emitting unit 32, a light receiving unit 36, and a rotating body 34. The target to be mounted with the electric motor 20 and the control device 100 is not limited to the object detection device 300, and a device for which the S/N is required to be improved with respect to a desired rotation angle range over other rotation angle ranges, for example, a light source. It may be a light irradiation device for irradiation, a spraying device for spraying a drug or the like, or an imaging device.

The control unit 10 is a microprocessor including a calculation unit, a storage unit, and an input/output unit, and is detected by the rotation angle sensor 12 by expanding and executing various programs stored in the storage unit in the storage unit. The amount of change in the rotation angle of the electric motor 20 per unit time is controlled according to the rotation angle. More specifically, the control unit 10 controls the amount of change in the rotation angle by controlling the rotation speed or the position of the electric motor 20 according to the rotation control signal, and further, as shown in FIG. In one rotation cycle, the change amount of the rotation angle in the first rotation angle range Ra1 is controlled to be smaller than the change amount of the rotation angle in the second rotation angle range Ra2 which is the rotation angle range other than the first rotation angle range Ra1. To do. As a result, it is possible to improve the SN ratio in the first rotation angle range Ra1 as compared with the related art in which the change amount of the rotation angle is not changed. In the first embodiment, the first rotation angle range Ra1 corresponds to a region of interest in which the accuracy of object detection in the object detection device 300 is desired to be improved. Note that, in the first embodiment, the electric motor 20 is used as a drive unit of the rotating body 34 in the object detection device 300, and the detected azimuth of the object is detected. Call. The control unit 10 further controls the light emission timing of the irradiation light output from the light emitting unit 32, and calculates the distance to the reflected object using time until the irradiation light hits the object and is received as reflected light by the light receiving unit 36. To do. The control unit 10 is connected to the rotation angle sensor 12, the electric motor driver 21, the light emitting unit 32, and the light receiving unit 36 by a signal line, receives a detection signal from the rotation angle sensor 12 and the light receiving unit 36, and A control signal is transmitted to the light emitting unit 32.

The rotation angle sensor 12 is a rotation angle detection unit for detecting the rotation angle of the electric motor 20. The rotation angle sensor 12 is, for example, a sensor that outputs the rotation angle as an absolute value, that is, as a rotation angle value, or the rotation angle as a count value, that is, the detection of a detection tooth or a detection hole is performed as a voltage value or a current value. It is a sensor that outputs as a value. The rotation angle sensor 12 is preferably a sensor that can detect the rotation angle of the electric motor 20 accurately and quickly. For example, a rotary encoder capable of optically reading a scale engraved on a rotating disk and outputting a detected angle value. Can be used. The detection of the rotation angle of the electric motor 20 can also be called detection of the position or the rotational position of the electric motor 20. Other than this, as the rotation angle sensor 12, for example, a Hall element sensor or a resolver can be used.

The electric motor 20 includes a rotating body 34 at the end of the output shaft, and drives the rotating body 34 to rotate. The rotation speed and position of the electric motor 20 are controlled by the electric motor driver 21 which receives the rotation control signal from the control unit 10. As the electric motor 20, various electric motors such as a brush motor can be used, but it is desirable to use a brushless motor that can easily control the instantaneous torque by the rotation angle.

In the first embodiment, the light emitting unit 32, the light receiving unit 36, and the rotating body 34 form an object detecting unit. The light emitting unit 32 includes, for example, a laser diode as a light source and emits infrared laser light. The light emitting unit 32 includes a light source driver (not shown), and drives the laser diode in a light emitting pattern according to a light emission control signal input from the control unit 10 to emit laser light. The light source forming the light emitting unit 32 may be one or plural.

The light receiving unit 36 includes, for example, one or a plurality of photodiodes as a light receiving element or a light receiving element array. The light receiving unit 36 converts a current corresponding to the amount of incident light incident on each light receiving element into a voltage and outputs it as a light receiving signal to the control unit 10.

The rotating body 34 includes, for example, a monohedral or a polygonal mirror such as a polygon mirror, and is rotationally driven by the electric motor 20. By arranging the light emitting unit 32 and the light receiving unit 36 along the rotation axis of the rotating body 34, the laser light emitted from the light emitting unit 32 is transmitted through the mirror, for example, over an azimuth angle of 360° in the horizontal direction. Illuminated to scan the object. The laser light reflected by the object passes through the same optical path as the irradiation light and is incident on the light receiving unit 36 via the mirror. This allows scanning over 360° azimuth to detect objects. When a plurality of light sources are provided as the light emitting unit 32, or when a mirror included in the rotating body 34 or a separate mirror swings in the vertical direction or is a polygon mirror, as a line in the horizontal direction It is possible to perform not only the scanning of, but also the scanning of the plane including the vertical direction. Further, the light emitting unit 32 and the light receiving unit 36 may be mounted on the rotating body 34 together with the mirror and may rotate together with the rotating body 34, or may be separate from the rotating body 34. Further, the rotating body 34 is provided with a plurality of light emitting portions 32 and light receiving portions 36 arranged in an array without a mirror, and directly irradiates the outside with laser light and directly receives reflected light. May be provided. The scanning range and the scanning rotation angle of the object detection device 300, that is, the scanning execution range accompanied by the irradiation of the laser beam executed by the object detection unit may not be 360°, and may be 180° or more or less than 180°. Such a scanning range may be used. However, even in this case, the rotating body 34 is rotationally driven.

With reference to FIG. 2, a rotation control process of the electric motor 20 executed by the electric motor control device 100, more specifically, the control unit 10, will be described. In the rotation control process of the electric motor 20 according to the first embodiment, the rotation speed is controlled by the rotation control signal to change the rotation angle of the electric motor 20 per unit time according to the rotation angle detected by the rotation angle sensor 12. Control the amount. The process flow shown in FIG. 2 is repeatedly executed, for example, at a predetermined interval, for example, in units of several msec after the electric motor 20 is started. In the case where the electric motor 20 is used as a drive unit of the object detection device 300 and the object detection device 300 is mounted in a vehicle, a period from when the system of the vehicle is activated until the system is terminated. Alternatively, while the operation switch of the object detection device 300 is turned on, it is repeatedly executed at a predetermined interval, for example, a unit of several msec.

The control unit 10 acquires the azimuth angle θ using the rotation angle signal input from the rotation angle sensor 12 (step S100). When the rotation angle signal is an absolute value signal, the control unit 10 acquires the rotation angle or the rotation position indicated by the rotation angle signal as the azimuth angle θ of the electric motor 20, and the rotation angle signal is the count signal. In this case, the azimuth angle θ of the electric motor 20 is acquired by adding it to the reference rotation angle or the reference position.

The control unit 10 acquires the rotation speed command value x according to the acquired azimuth angle θ (step S102). The rotation speed command value x is calculated and acquired by the control unit 10 calculating the following function, for example.
When θ ^* =mod(θ, 2π) is defined, the rotational speed command value x can be defined as a function f(θ ^* ) having θ ^* as a variable, that is, x=f(θ ^* ). Note that θ is the detected rotation angle of the electric motor 20.

The control unit 10 outputs a rotation control signal indicating the acquired rotation speed command value x to the electric motor driver 21 (step S104), and ends this processing routine. The electric motor driver 21 supplies a current value or a voltage value according to the input rotational speed command value x to the electric motor 20 to control the rotational speed N (rpm) of the electric motor 20.

The operation characteristics of the electric motor 20 when the rotation control signal for instructing the rotational speed command value x is output to the electric motor driver 21 using the above function will be described with reference to FIG. In FIG. 3, a characteristic line L1 indicated by a solid line indicates a rotation control signal, and a characteristic line L2 indicated by a broken line indicates an actual rotation angle of the electric motor 20, that is, an azimuth angle. When the azimuth angle θ of the electric motor 20=the first determination azimuth angle θa, the rotation speed command value x takes a value that reduces the rotation speed N of the electric motor 20 from the normal rotation speed N1 toward the reduced rotation speed N2. When the azimuth θ exceeds the second determination azimuth θb, the rotation speed command value x takes a value that increases the rotation speed N of the electric motor 20 from the reduced rotation speed N2 toward the normal rotation speed N1. Although the actual azimuth θ of the electric motor 20 has a time lag, it changes following the rotation control signal.

With reference to FIG. 4, a technical advantage of the object detection device 300 obtained by changing the amount of change in the rotation angle of the electric motor 20 will be described. As described above, in one rotation cycle of the electric motor 20, the change amount of the rotation angle in the first rotation angle range Ra1 is calculated from the change amount of the rotation angle in the second rotation angle range Ra2 other than the first rotation angle range Ra1. If the control is also made small, the SN ratio in the first rotation angle range Ra1 can be improved as compared with the related art in which the change amount of the rotation angle is not changed. In FIG. 4, a characteristic line L3 indicated by a solid line is an S/N characteristic in the first embodiment, and a characteristic line L4 indicated by a broken line is a conventional example, that is, an S/N when the amount of change in the rotation angle of the electric motor 20 is not changed. Show the characteristics. Further, the S/N characteristics shown in FIG. 4 are characteristics in a system in which the relationship of S/N∝(x) ^-0.5 is established. As shown in FIG. 4, according to the electric motor control device 100 according to the first embodiment, the S/N in the first rotation angle range Ra1 is improved as compared with the case where the change amount of the rotation angle is not changed. be able to. Therefore, the S/N characteristic in the first rotation angle range Ra1 can be absolutely improved. Further, according to the electric motor control device 100 of the first embodiment, it becomes possible to improve the S/N in the first rotation angle range Ra1 more than the S/N in the second rotation angle range Ra2. It is possible to reduce the S/N characteristic in the unnecessary rotation angle range while improving the S/N characteristic in the required rotation angle range.

According to the electric motor control device 100 according to the first embodiment described above, in one rotation cycle of the electric motor 20, the amount of change in the rotational angle in the first rotational angle range Ra1 is determined according to the rotational angle of the electric motor 20. , And the change amount of the rotation angle in the second rotation angle range Ra2 can be made different. That is, according to the electric motor control device 100 of the first embodiment, the rotation speed N of the electric motor 20 in the first rotation angle range Ra1 is lower than the rotation speed N of the electric motor 20 in the second rotation angle range Ra2. By doing so, the amount of change in the rotation angle in the first rotation angle range Ra1 can be reduced. When the motor control device 100 is used as a drive unit of the detection unit of the object detection device 300, the first rotation angle range Ra1 corresponds to a region of interest in which the accuracy of object detection in the object detection device 300 is desired to be improved. Therefore, according to the object detection device 300 according to the first embodiment, it is possible to secure the detection time and the integration time in the first rotation angle range Ra1, improve the detection resolution, and the first rotation. The S/N characteristic in the angular range Ra1 can be absolutely improved with respect to the S/N characteristic in the second rotation angle range Ra2. The amount of change in the rotation angle in the first rotation angle range Ra1 makes the rotation speed N of the electric motor 20 in the first rotation angle range Ra1 higher than the rotation speed N of the electric motor 20 in the second rotation angle range Ra2. Therefore, it may be larger than the second rotation angle range Ra2. For example, when the position change of the detection target is fast, by increasing the rotation speed N of the electric motor 20 in the first rotation angle range Ra1, it is possible to suppress or prevent the accuracy decrease due to the fast position change.

In the above-described first embodiment, the rotation speed command value x is acquired by calculation using a function. On the other hand, as shown in FIG. 5, the rotation speed N of the electric motor 20 may be controlled using the normal rotation speed command value and the reduced rotation speed command value prepared in advance. The process flow shown in FIG. 5 is executed under the same conditions as the process flow shown in FIG.

The control unit 10 acquires the azimuth angle θ using the rotation angle signal input from the rotation angle sensor 12 (step S200). The control unit 10 determines whether the acquired azimuth angle θ is equal to or greater than the first determination azimuth angle θa and equal to or less than the second determination azimuth angle θb, that is, whether the relationship of θa≦θ≦θb is satisfied. Yes (step S202). The first determination azimuth angle θa is a start azimuth angle of the first rotation angle range Ra1, and the second determination azimuth angle θb is an end azimuth angle of the first rotation angle range Ra1.

When determining that the acquired azimuth angle θ satisfies the relationship of θa≦θ≦θb (step S202: Yes), the control unit 10 sets the rotation speed command value x to the reduced rotation speed N2 (step S204). , And proceeds to step S208. In this embodiment, as shown in FIGS. 6 and 7, as the rotation speed command value x for instructing the rotation speed N of the electric motor 20, a command value for instructing the normal rotation speed N1 in the normal time and a reduction rotation in the reduction time are used. The command value for instructing the speed N2 may be prepared in advance and stored in the map, or a discontinuous function for outputting the rotation speed command value x shown in FIGS. 6 and 7 as a calculation result may be used. .. In the example of FIG. 6, the first rotation angle range Ra1 and the second rotation angle range Ra2 are the same range, and in the example of FIG. 7, the first rotation angle range Ra1 is the second rotation angle range Ra2. Is more narrowly defined. Note that the normal rotation speed N1>reduced rotation speed N2. Further, the difference between the maximum value of the rotation speed command value x, that is, the normal rotation speed N1 and the minimum value, that is, the reduction rotation speed N2 is at least twice or more, in other words, the reduction rotation speed with respect to the normal rotation speed N1. It is desirable to secure a sufficient detection time and measurement time by setting the speed of N2 to 1/2 or less. Further, in order to avoid the delay of the detection time, it is desirable that the rotation angle range in which the rotation speed command value x has the minimum value is 0.5π[rad] or less.

When determining that the acquired azimuth angle θ does not satisfy the relationship of θa≦θ≦θb (step S202: No), the control unit 10 sets the rotation speed command value x to the normal rotation speed N1 (step S202). S206) and the process proceeds to step S208.

When the discontinuous normal rotation speed N1 and the reduced rotation speed N2 are used as the rotation speed command value x, the rotation speed command value x is discontinuous, that is, changes stepwise, so that there is a sharp S/N ratio. Allocation can be realized. As shown in FIG. 7, when the attention area is narrow, the first rotation angle range Ra1 is set to be narrow to increase the rotation range of the higher normal rotation speed N1 and to increase the average rotation speed of the electric motor 20. The frame rate can be increased and the frame rate can be improved. Note that a function showing a sine wave as shown in FIG. 8 may be used in order to reduce large acceleration/deceleration due to a large speed change rate when using a discontinuous function and generation of bending.

Second embodiment:
In the first embodiment, by controlling the rotation speed N of the electric motor 20, the change amount of the rotation angle in the first rotation angle range Ra1 is smaller than the change amount of the rotation angle in the second rotation angle range Ra2. Was made smaller. In the second embodiment, by controlling the position of the electric motor 20, the change amount of the rotation angle in the first rotation angle range Ra1 is made smaller than the change amount of the rotation angle in the second rotation angle range Ra2. It Since the configurations of the electric motor control device 100 and the object detection device 300 are the same as those in the first embodiment, the same reference numerals are given and the description of each configuration is omitted.

The rotation control process of the electric motor 20 according to the second embodiment, more specifically, the rotation control process of the electric motor 20 executed by the control unit 10 is the rotation speed command value x in step S102 in the process flow shown in FIG. Instead, the difference is that the azimuth position command value θin is used, and the other steps are the same, so the same step numbers are assigned and detailed description is omitted. Further, the execution conditions of the processing flow in the second embodiment are the same as the execution conditions in the processing flow shown in FIG. The azimuth position command value is synonymous with the rotation angle position command value.

The control unit 10 acquires the azimuth angle θ using the rotation angle signal input from the rotation angle sensor 12 (step S100). The control unit 10 acquires the azimuth angle position command value θin according to the acquired azimuth angle θ. The azimuth position command value θin is calculated and acquired by the control unit 10 calculating the following function, for example. In the conventional azimuth position control, the azimuth position command value θin is a linear function of time t, and is defined as, for example, θin=a·t+b (where a and b are constants). On the other hand, in the second embodiment, the azimuth angle position command value θin is defined as a higher-order function with respect to time t. It should be noted that the function f(t) is a function whose output has a period of 2π[rad] with respect to the period of To [sec],
When t ^* =mod(t,To) and θin ^* (t)=mod(θin(t),2π), the azimuth position command value θin is θin ^* (t)=f(t ^* ). Can be defined as However, under the condition of maximizing the S/N at θin ^* =0,
|(dθin ^* (t)/dt)|=min(dθin ^* (t)/dt) (θin ^* =0).

The control unit 10 outputs a rotation control signal indicating the acquired azimuth position command value θin to the electric motor driver 21 (step S104), and ends this processing routine. The electric motor driver 21 supplies a current value or a voltage value according to the input azimuth position command value θin to the electric motor 20 to control the rotational position θ(rad) of the electric motor 20.

The operation characteristics of the electric motor 20 when the rotation control signal instructing the azimuth angle position command value θin is output to the electric motor driver 21 using the above function will be described with reference to FIG. 9. In FIG. 9, a characteristic line L5 shown by a solid line shows a rotation control signal in the second embodiment, and a characteristic line L6 shown by a broken line shows a conventional rotation control signal. According to the characteristic line L6 indicating the azimuth angle position command value calculated using the linear function, the position change amount is the same in all azimuth angles. On the other hand, according to the characteristic line L5 indicating the azimuth position command value calculated by using the higher-order function according to the second embodiment, the position change amount at θin ^* =0 is the minimum, and The position change amount in the azimuth angle corresponding to the first rotation angle range Ra1 is smaller than the position change amount in the azimuth angle corresponding to the second rotation angle range Ra2. According to the electric motor control device 100 according to the second embodiment, the S/N in the first rotation angle range Ra1 can be improved as compared with the case where the change amount of the rotation angle is not changed. Therefore, the S/N characteristic in the first rotation angle range Ra1 can be absolutely improved. Further, according to the electric motor control device 100 according to the second embodiment, it becomes possible to improve the S/N in the first rotation angle range Ra1 more than the S/N in the second rotation angle range Ra2. It is possible to improve the S/N characteristic in the required rotation angle range and reduce the S/N characteristic in the unnecessary rotation angle range.

According to the electric motor control device 100 according to the second embodiment described above, in one rotation cycle of the electric motor 20, the change amount of the rotation angle in the first rotation angle range Ra1 is calculated in the second rotation angle range Ra2. It can be different from the change amount of the rotation angle. That is, according to the electric motor control device 100 of the first embodiment, the displacement amount of the rotational position θ of the electric motor 20 in the first rotation angle range Ra1, that is, the time change amount is calculated in the second rotation angle range Ra2. By making it smaller than the amount of displacement of the rotational position θ of the electric motor 20, it is possible to reduce the amount of change in the rotation angle in the first rotation angle range Ra1. According to the electric motor control device 100 according to the second embodiment, there is a technical advantage that the rotational position of the electric motor 20 at each time t is clear and the rotational position control of the electric motor 20 is easy. As a result, it is easier to make the amount of change in the rotation angle of the electric motor 20 in the first rotation angle range Ra1 smaller than the amount of change in the second rotation angle range Ra2. Further, when the motor control device 100 according to the second embodiment is used as a drive unit of the detection unit of the object detection device 300, the same technical effect as that of the object detection device 300 according to the first embodiment can be obtained. You can Further, the time integrated value of the function for deriving the azimuth position command value θin, that is, the difference between the maximum value and the minimum value of the speed is at least twice or more, in other words, the minimum speed is 1 with respect to the maximum speed. It is desirable to secure sufficient detection time and measurement time at a speed of ½ or less. Further, in order to avoid the delay of the detection time, it is desirable that the rotation angle range in which the time integrated value of the function for deriving the azimuth angle command value θin becomes the minimum value is 0.5π[rad] or less. . The change amount of the rotation angle in the first rotation angle range Ra1 is the change amount of the rotation position θ of the electric motor 20 in the first rotation angle range Ra1 to the rotation position θ of the electric motor 20 in the second rotation angle range Ra2. It may be made larger than the second rotation angle range Ra2 by making it larger than the change amount. For example, when the position change of the detection target is fast, by increasing the amount of change of the rotational position θ of the electric motor 20 in the first rotation angle range Ra1, it is possible to suppress or prevent the accuracy decrease due to the fast position change. it can.

Third embodiment:
Another embodiment of using the electric motor control device 100 in the object detection device 300 will be described. In the object detection device 300 according to the first and second embodiments, since the amount of change in the rotation angle of the electric motor 20 is changed, scanning or distance measurement for object detection is performed at a constant light emission cycle shown in FIG. Even if it is executed, the S/N characteristic in the desired rotation angle range Ra can be improved. When the constant light emission cycle shown in FIG. 10 is adopted, it is possible to group the detection results of a plurality of times and use the average value as the detection value. However, in this case, since the azimuth angle of the electric motor 20 changes even while acquiring the detection results of a plurality of times, the detection accuracy of the object with respect to the azimuth angle of the electric motor 20, that is, the detection positions of the electric motor 20 and the object. The accuracy of correspondence with Therefore, in the third embodiment, as shown in FIG. 11, the execution interval of the detection to be averaged is shortened. As a result, it is possible to improve the acquisition accuracy of the azimuth angle of the electric motor 20 or suppress a decrease in the acquisition accuracy and improve the detection accuracy of the object in the object detection device 300. In the example of FIG. 11, since the number of times of measurement in the unit time is the same, the acquisition frequency of the detection value obtained by averaging is maintained.

Fourth Embodiment:
In the third embodiment, the problems and solutions when the detected values are obtained by averaging have been described. In the fourth embodiment, further, as shown in FIG. 12, during the time required to average the detected values, the change in the azimuth angle of the electric motor 20 is stopped, that is, the azimuth angle position at which the azimuth angle is stopped at any azimuth angle. The command value θd is used. In practice, the electric motor 20 does not completely stop in a short time due to the moment of inertia, but at least the command value for stopping the electric motor 20 at the desired azimuth angle is output as the azimuth position command value θd. The azimuth position control of the electric motor 20 that approximates the characteristic of the azimuth position command value θd is executed, and the detection accuracy of the object can be improved.

Other embodiments:
(1) In the above embodiment, Lidar that emits a laser beam is used as an example of the object detection device 300, but it may be applied to a radar that emits a radio wave. Scanning is also executed in the radar, and the technical advantages obtained in the above embodiment can be similarly enjoyed.

(2) In each of the above-described embodiments, a unit for determining the target rotation angle in the first rotation angle range Ra1, that is, the target azimuth angle is provided, and the function for deriving the rotation speed command value x in the target azimuth angle is provided. It may be determined so that the output value becomes the minimum and the time integral value of the function for deriving the azimuth angle position command value θin becomes the minimum. In this case, the detection accuracy or S/N at the azimuth angle of interest can be maximized. Further, as the azimuth angle of interest, when the object detection device 300 is mounted on a vehicle, for example, the vehicle azimuth is normally set, and the right/left turn azimuth is set for right/left turn. If detected, the azimuth of the falling object may be set as the azimuth of interest. In these cases, the object detection in the azimuth is more significant, and the improvement in the object detection accuracy can improve the effect of the driving support process. Further, in each of the above-described embodiments, the amount of change in the rotation angle of the electric motor 20 is changed between the first rotation angle range Ra1 and the second rotation angle range Ra2, but in the first rotation angle range Ra1 A target rotation angle range including the target azimuth angle may be determined, and the change amount in the first rotation angle range Ra1 may be set as the variable change amount. Specifically, the control unit 10 makes the amount of change in the target rotation angle range smaller than the amount of change in the other rotation angle ranges in the first rotation angle range Ra1, that is, further lowers the rotation speed in the target rotation angle range. Alternatively, the change amount of the azimuth angle position may be further reduced. In this case, it is possible to improve the object detection accuracy in the first rotation angle range Ra1 and further improve the object detection accuracy particularly in the noted rotation angle range. The amount of change in the rotation angle range of interest may be changed to be different from the amount of change in the other rotation angle range of the first rotation angle range Ra1. In the above example, the control unit 10 The change amount in the rotation angle range is larger than the change amounts in the other rotation angle ranges in the first rotation angle range Ra1, that is, the rotation speed in the target rotation angle range is further increased, or the change amount in the azimuth angle position is further increased. You can increase it.

(3) In each of the above embodiments, the light emission interval in the first rotation angle range Ra1 and the light emission interval in the second rotation angle range Ra2 may be different. More preferably, it is desirable that the light emission interval in the first rotation angle range Ra1 be shorter than the light emission interval in the second rotation angle range Ra2 to improve the detection resolution.

(4) The control unit and the method thereof in each of the above-described embodiments are realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. , May be realized. Alternatively, the control unit and its method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described in the present disclosure are configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured by one or more hardware logic circuits. It may be realized by one or more dedicated computers. Further, the computer program may be stored in a computer-readable non-transition tangible recording medium as an instruction executed by a computer.

Although the present disclosure has been described above based on the embodiments and the modifications, the embodiments of the present invention described above are intended to facilitate understanding of the present disclosure and do not limit the present disclosure. The present disclosure may be modified or improved without departing from the spirit and scope of the claims, and the present disclosure includes equivalents thereof. For example, the technical features in the embodiments and modifications corresponding to the technical features in each mode described in the section of the summary of the invention are to solve some or all of the above problems, or In order to achieve some or all of the effects, it is possible to appropriately replace or combine them. If the technical features are not described as essential in this specification, they can be deleted as appropriate.

10... Control part, 12... Rotation angle sensor, 20... Electric motor, 21... Electric motor driver, 32... Light emitting part, 34... Rotating body, 36... Light receiving part, 100... Electric motor control device, 300... Object detection device.

Claims (8)

A control device (100) for an electric motor (20),
A rotation angle detection unit (12) for detecting the rotation angle of the electric motor,
A control unit (10) for controlling the amount of change in the rotation angle of the electric motor per unit time according to the rotation angle detected by the rotation angle detection unit, wherein A control unit for an electric motor, comprising: a control unit (10) that makes the amount of change in the rotation angle range different from the amount of change in the second rotation angle range other than the first rotation angle range. The motor control device according to claim 1,
The control unit of the electric motor, wherein the control unit makes the amount of change in the first rotation angle range smaller than the amount of change in the second rotation angle range. The control device for the electric motor according to claim 1,
The control unit controls the amount of change by changing a rotation speed command value for the electric motor, and defines the rotation speed in the first rotation angle range as the rotation speed in the second rotation angle range. A control device for an electric motor, which is made different or lower than the rotation speed in the second rotation angle range. The control device for the electric motor according to claim 3,
The control unit further determines a target rotation angle or a target rotation angle range in the first rotation angle range, and further makes the rotation speed in the target rotation angle or the target rotation angle range different or lower. Control device. The control device for the electric motor according to claim 1,
The control unit controls the amount of change by instructing the position of the electric motor, and sets the amount of displacement of the position in the first rotation angle range to the amount of displacement of the position in the second rotation angle range. Are different or smaller than the displacement amount of the position in the second rotation angle range. The control device for the electric motor according to claim 5,
The control unit further determines a target rotation angle or a target rotation angle range in the first rotation angle range, and further changes or reduces the position change amount in the target rotation angle or the target rotation angle range, Electric motor controller. An object detection device (300),
A control device (100) for an electric motor according to any one of claims 1 to 6,
An object detection unit (32, 34, 36) rotationally driven by the electric motor, the object detection unit detecting an object using a radio wave or a laser beam;
An object detection device comprising. A method of controlling an electric motor,
Detecting the rotation angle of the electric motor,
According to the detected rotation angle, in one rotation cycle of the electric motor, a change amount of the rotation angle of the electric motor per unit time in the first rotation angle range is set to a value other than the first rotation angle range. A method of controlling an electric motor, the method comprising: making the amount of change different from the amount of change in the rotation angle range of 2.

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