KR102590227B1 - Galvano Mirror Scanner - Google Patents

Abstract

A galvano mirror scanner is disclosed that can minimize the stationary section of a mirror by generating a drive waveform for driving a drive motor in consideration of the inertia due to rotation of the mirror.
The disclosed galvano mirror scanner,
mirror; a drive motor that rotates a rotation axis connected to the mirror; It includes a motor control unit that generates a drive waveform for driving the drive motor in consideration of inertia according to rotation of the mirror.

Description

Galvano Mirror Scanner {Galvano Mirror Scanner}

The present invention relates to a galvano mirror scanner that can minimize the stationary section of the mirror by generating a drive waveform for driving a drive motor in consideration of the inertia due to rotation of the mirror.

Recently, as vehicles have become more intelligent, research on autonomous vehicles and advanced driver assistance systems (ADAS) has been actively conducted.

Figure 1 is a diagram showing an example of the detection range of various sensors applied to a vehicle.

In order to implement such autonomous vehicles or vehicle driving assistance systems, various sensors are essentially required. These sensors include RADAR, LIDAR, cameras, ultrasonic sensors, etc., as shown in FIG. 1. In particular, in the case of LIDAR, although the accuracy of object identification is somewhat low, due to its advantage in obtaining accurate distance information, it is installed and used on the front and rear of most autonomous vehicles.

Meanwhile, in the case of a LIDAR mounted on a vehicle, it includes a transmitter that generates light and transmits it to an object, a receiver that receives light reflected from the object, and a signal processor that processes signals for the light of these transmitters and receivers. do. Of course, these transmitting units, receiving units, and signal processing units are provided in a housing, and a window cover made of a transparent material is installed on the housing to allow light to enter and exit.

In particular, methods for scanning light from the lidar transmitter include mechanical scan, MEMS mirror scan, and galvano scan.

In the case of the mechanical scanning method, it is easy to increase the detection distance by using a motor to increase the size of the mirror, but it is bulky.

In the case of the MEMS mirror scan method, the MEMS mirror is not shared in the optical path of the transmitter and receiver due to limitations in mirror size, and the scanning angle is limited. Because the scanning angle is small, the MEMS mirror scan method is expensive as multiple MEMS configurations must be applied, and optical distortion occurs as post optics are applied to the front. In addition, the MEMS mirror scan method is not only vulnerable to optical noise because the receiver has a wide viewing angle, but also the optical system configuration of the transmitter inevitably becomes complicated due to limitations in mirror size.

Meanwhile, the galvano scan method uses a galvanometer scanner and allows for a wider scanning angle than the MEMS mirror scan method.

Figure 2 is a diagram showing the driving waveform of a galvano mirror scanner according to the prior art. At this time, the driving waveform may mean the voltage value of the driving motor that rotates the galvano mirror.

Referring to FIG. 2, the driving waveform of the galvano mirror scanner according to the prior art can be broadly classified into three sections. Section Ⅰ is a forward voltage increase section for forward rotation of the galvano mirror, and section Ⅲ is a reverse voltage increase section for reverse rotation of the galvano mirror.

Section Ⅱ is a rotation stop section to change the rotation direction of the galvano mirror and is a voltage maintenance section. In section Ⅱ, the rotation of the galvano mirror is temporarily stopped, so no actual scanning operation is performed during this section, so object detection may be temporarily suspended. This may increase the likelihood of a vehicle accident occurring.

Therefore, the development of a galvano mirror scanner that can minimize the stop section of the galvano mirror is required.

Korean Patent Publication No. 10-2022-0024759

The purpose of the present invention is to provide a galvano mirror scanner that can minimize the stationary section of the mirror by generating a drive waveform for driving a drive motor in consideration of the inertia due to rotation of the mirror.

The galvano mirror scanner according to an embodiment of the present invention,

mirror; a drive motor that rotates a rotation axis connected to the mirror; It includes a motor control unit that generates a drive waveform for driving the drive motor in consideration of inertia according to rotation of the mirror.

In the galvano mirror scanner according to an embodiment of the present invention, the drive waveform is a voltage value waveform of the drive motor that rotates the mirror, and the voltage value increases from the beginning of the one-way rotation section of the mirror to the end of the one-way rotation section. It may be a waveform with a decreasing slope.

In the galvano mirror scanner according to an embodiment of the present invention, when the average rotational angular speed during one cycle (T) of the mirror is referred to as a reference speed, and the voltage value that makes the reference speed is referred to as a reference voltage, the rotation section includes at least one acceleration section and at least one deceleration section, wherein the acceleration section has a voltage value set to have a slope greater than the slope of the reference voltage, and the deceleration section has a slope less than the slope of the reference voltage. The voltage value can be set.

In the galvano mirror scanner according to an embodiment of the present invention, the rotation section further includes a constant speed section in which the voltage value is set to have the same slope as the slope of the reference voltage, and the constant speed section includes the acceleration section and the deceleration section. can be formed in between.

In the galvano mirror scanner according to an embodiment of the present invention, the driving waveform may be configured in a linear form.

In the galvano mirror scanner according to an embodiment of the present invention, the driving waveform may be configured in a non-linear form in the remaining sections excluding the constant velocity section.

In the galvano mirror scanner according to an embodiment of the present invention, the driving waveform may have a non-linear form in which the slope of the voltage value increases in the acceleration section and may have a non-linear form in which the slope of the voltage value decreases in the deceleration section. there is.

Details of other implementations of various aspects of the present invention are included in the detailed description below.

According to the galvano mirror scanner according to an embodiment of the present invention, the motor control unit generates a driving waveform in which the voltage value is set so that the voltage value slope decreases from the beginning to the end of the rotation section, so that the rotation direction of the mirror is changed at the point. By reducing the effect of inertia due to rotation of the mirror, the pause period of the mirror can be minimized. Accordingly, the scanning stop section can be minimized, thereby reducing the possibility of a vehicle accident occurring.

Figure 1 is a diagram showing an example of the detection range of various sensors applied to a vehicle.
Figure 2 is a diagram showing the driving waveform of a galvano mirror scanner according to the prior art.
Figure 3 is a block diagram showing the configuration of a LIDAR including a galvano mirror scanner according to an embodiment of the present invention.
Figure 4 is a diagram showing a galvano mirror scanner according to an embodiment of the present invention.
Figure 5 is a diagram illustrating a first drive waveform generated by the motor control unit of a galvano mirror scanner according to an embodiment of the present invention.
Figure 6 is a diagram showing a second drive waveform generated by the motor control unit of the galvano mirror scanner according to an embodiment of the present invention.
Figure 7 is a diagram illustrating a computing device according to an embodiment of the present invention.

Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be exemplified and explained in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all transformations, equivalents, and substitutes included in the spirit and technical scope of the present invention.

The terms used in the present invention are only used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as 'include' or 'have' are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof. Hereinafter, a galvano mirror scanner according to an embodiment of the present invention will be described with reference to the drawings.

Figure 3 is a block diagram showing the configuration of a LIDAR including a galvano mirror scanner according to an embodiment of the present invention.

LiDAR according to an embodiment of the present invention is a sensor device that can generate information about an object (OB) outside the vehicle using laser light. The lidar according to an embodiment of the present invention may be implemented in a driven manner. In the case of a driven type, it is rotated by a motor and can detect objects (OB) around the vehicle.

In addition, the lidar according to an embodiment of the present invention detects an object OB based on a time of flight (TOF) method or a phase-shift method using laser light, and determines the location of the detected object OB, The distance to the detected object (OB), relative speed, etc. can be detected.

Additionally, the lidar according to an embodiment of the present invention may be placed at an appropriate location in the vehicle to detect an object (OB) located in front, behind, or on the side of the vehicle. At this time, the vehicle may be an autonomous vehicle or may be equipped with an advanced driver assistance system (ADAS), etc., and may operate autonomously using information detected by the lidar according to an embodiment of the present invention. Alternatively, vehicle driver assistance operations, etc. may be performed.

Specifically, the lidar according to an embodiment of the present invention may include a transmitter 100, a receiver 200, and a signal processor 300, as shown in FIG. 3.

The transmitter 100 generates laser light and transmits it to the object OB. The transmitter 100 includes a light source unit 110 that generates laser light, and a galvano mirror scanner 120 that scans the laser light incident from the light source unit 110 at various angles of view.

The light source unit 110 may generate laser lights of the same wavelength or different wavelengths. For example, the light source unit 110 can generate laser light with a specific wavelength or variable wavelength in the wavelength range of 250 nm to 11 μm, and can be implemented through a small, low-power semiconductor laser diode. , but is not limited to this. The galvano mirror scanner 120 will be described later with reference to FIGS. 4 and 5.

The receiver 200 receives light reflected from the object OB. For example, the receiver 200 may convert light reflected and received from the object OB into an electrical signal (current, etc.) using a photoelectric conversion element such as a photodiode. At this time, the measurement angle of the receiver 200 may be referred to as FOV (Field Of View).

The signal processing unit 300 processes light signals from the transmitting unit 100 and the receiving unit 200. The signal processing unit 300 may include a processor that is electrically connected to the transmitting unit 100 and the receiving unit 200, processes the received signal, and generates data for the object OB based on the processed signal. . At this time, the signal processing unit 300 can calculate the separation distance of the object OB, etc. by collecting and processing data according to the light.

For example, the signal processing unit 300 may convert the output detected by the receiving unit 200 into a voltage, amplify it, and then convert the amplified signal into a digital signal using an analog to digital converter (ADC). Additionally, the signal processing unit 300 may detect the distance, shape, etc. of the object (OB) by performing signal processing on the changed data using a time-of-flight (TOF) method, a phase-shift method, etc.

At this time, the TOF method measures the time for the pulse signal reflected from the object (OB) within the detection range to arrive at the receiver 200 after the laser pulse signal is emitted from the transmitter 100, thereby determining the separation distance from the object (OB). This is a method of measuring.

In addition, the phase-shift method emits a laser beam that is continuously modulated with a specific frequency from the transmitter 100, and then measures the amount of phase change of the signal reflected and returned from the object (OB) within the detection range, thereby measuring the corresponding time and This is a method of calculating the separation distance.

Figure 4 is a diagram showing a galvano mirror scanner according to an embodiment of the present invention, and Figure 5 is a diagram showing a first drive waveform generated by the motor control unit of the galvano mirror scanner according to an embodiment of the present invention. It is a diagram, and FIG. 6 is a diagram illustrating a second drive waveform generated by the motor control unit of a galvano mirror scanner according to an embodiment of the present invention.

As shown in FIG. 4, the galvano mirror scanner 120 according to an embodiment of the present invention includes a mirror 121 connected to the rotation axis 122, and a rotation axis 122 to adjust the angle of the mirror 121. It includes a drive motor 123 that rotates. In other words, the galvanometer scanner 120 can be used as a means to control the optical path by deflecting the angle of the laser light. The galvanometer scanner 120 is controlled by the drive motor 123 so that the mirror 121 rotates within a certain angle range.

At this time, the motor control unit 124 considers the inertia according to the rotation of the mirror 121 and generates a drive waveform as shown in FIG. 5 or FIG. 6 to drive the drive motor 123, thereby minimizing the mirror stop section. . At this time, the driving waveform may mean the voltage value of the driving motor 123 that rotates the galvano mirror 121.

5 and 6, the time interval 0 to 1/2T is the forward (e.g. clockwise) rotation section of the mirror 121, and the time section 1/2T to 1T is the reverse direction (e.g. clockwise) rotation section of the mirror 121. , counterclockwise) is a rotation section, and T is a period in which the mirror 121 performs forward/reverse rotation at a predetermined angle.

Each rotation section is divided into at least two or more detailed sections, and each detailed section may consist of at least one acceleration section and at least one deceleration section. Additionally, at least one constant speed section may be further included depending on selection. 5 and 6 show that the forward rotation section (0 to 1/2T) and the reverse rotation section (1/2T to 1T) are each an acceleration section (A1, A4), a constant speed section (A2, A5), and a deceleration section. The case consisting of (A3, A6) is exemplified. The virtual straight line L1 is the reference speed of the forward rotation section, and the virtual straight line L2 is the reference speed of the reverse rotation section. The reference speed is the average rotational angular speed during one cycle T time, and the reference speeds L1 and L2 are straight lines with the same size and different signs (+,-). The voltage value that sets the standard speed is called the reference voltage.

In Figure 5(a), the change in voltage value over time is shown as a first driving waveform. The motor control unit 124 sets the voltage value to have a slope greater than the slope of the reference voltage at the beginning of each rotation section (acceleration section), and sets the voltage value to have a slope smaller than the slope of the reference voltage at the end of the rotation section (deceleration section). Set . And, optionally, a constant speed section can be set, and the voltage value of the constant speed section is set to have the same slope as the slope of the reference voltage. The constant speed section is formed between the acceleration section and the deceleration section.

In Figure 5(b), the change in voltage value in Figure 5(a) is shown converted into a voltage slope. In terms of slope, the motor control unit 124 sets the voltage value so that the voltage slope decreases from the beginning to the end of each rotation section. (regardless of sign)

In Figure 6, the change in voltage value over time is shown as a second driving waveform. While the drive waveform in FIG. 5 is linear throughout the entire section, the drive waveform in FIG. 6 is non-linear in all sections except for the constant speed sections A2 and A5. Specifically, the voltage value has a non-linear form in which the slope increases in the acceleration sections (A1, A4) of the second driving waveform, and has a non-linear form in which the slope decreases in the deceleration sections (A3, A6).

According to the galvano mirror scanner according to the embodiment of the present invention as described above, the motor control unit 124 generates a drive waveform in which the voltage value is set so that the voltage value slope decreases from the beginning to the end of the rotation section, thereby generating the mirror 121 ), the effect of inertia due to the rotation of the mirror 121 can be reduced at the point where the direction of rotation of the mirror 121 is changed, thereby minimizing the temporary stop section of the mirror 121. Accordingly, the scanning stop section can be minimized, thereby reducing the possibility of a vehicle accident occurring.

7 is a diagram illustrating a computing device according to an embodiment of the present invention. The computing device TN100 of FIG. 7 may be a hardware configuration of the motor control unit 124 described in this specification.

In the embodiment of FIG. 7, the computing device TN100 may include at least one processor TN110, a transceiver device TN120, and a memory TN130. Additionally, the computing device TN100 may further include a storage device TN140, an input interface device TN150, an output interface device TN160, etc. Components included in the computing device TN100 may be connected by a bus TN170 and communicate with each other.

The processor TN110 may execute a program command stored in at least one of the memory TN130 and the storage device TN140. The processor TN110 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Processor TN110 may be configured to implement procedures, functions, and methods described in connection with embodiments of the present invention. The processor TN110 may control each component of the computing device TN100.

Each of the memory TN130 and the storage device TN140 can store various information related to the operation of the processor TN110. Each of the memory TN130 and the storage device TN140 may be comprised of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory TN130 may be comprised of at least one of read only memory (ROM) and random access memory (RAM).

The transceiving device TN120 can transmit or receive wired signals or wireless signals. The transmitting and receiving device (TN120) can be connected to a network and perform communication.

Meanwhile, the present invention may be implemented as a computer program. The present invention can be combined with hardware and implemented as a computer program stored on a computer-readable recording medium.

Methods according to embodiments of the present invention may be implemented in the form of programs readable through various computer means and recorded on a computer-readable recording medium. Here, the recording medium may include program instructions, data files, data structures, etc., singly or in combination.

Program instructions recorded on the recording medium may be those specifically designed and constructed for the present invention, or may be known and available to those skilled in the art of computer software.

For example, recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CDROMs and DVDs, and magneto-optical media such as floptical disks. optical media), and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc.

Examples of program instructions may include machine language, such as that created by a compiler, as well as high-level languages that can be executed by a computer using an interpreter, etc.

These hardware devices may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

Above, an embodiment of the present invention has been described, but those skilled in the art can add, change, delete or add components without departing from the spirit of the present invention as set forth in the patent claims. The present invention may be modified and changed in various ways, and this will also be included within the scope of rights of the present invention.

100: Transmitting unit
110: light source unit
120: Galvano mirror scanner
121: Mirror 122: Rotation axis
123: drive motor 124: motor control unit
200: Receiving unit
300: signal processing unit

Claims (7)

mirror;
a drive motor that rotates a rotation axis connected to the mirror;
It includes a motor control unit that generates a drive waveform for driving the drive motor in consideration of inertia according to rotation of the mirror,
The drive waveform is a voltage value waveform of the drive motor that rotates the mirror, and is a waveform in which the voltage value slope decreases from the beginning of the one-way rotation section of the mirror to the end of the one-way rotation section,
When the average rotational angular speed during one cycle (T) of the mirror is referred to as a reference speed, and the voltage value that makes the reference speed is referred to as a reference voltage, the rotation section includes at least one acceleration section and at least one deceleration section. And
A galvano mirror scanner, wherein the acceleration section is set to have a voltage value greater than the slope of the reference voltage, and the deceleration section is set to have a voltage value smaller than the slope of the reference voltage.
delete delete In claim 1,
The rotation section further includes a constant speed section in which a voltage value is set to have the same slope as the slope of the reference voltage, and the constant speed section is formed between the acceleration section and the deceleration section.
In claim 4,
A galvano mirror scanner, wherein the driving waveform is configured in a linear form.
In claim 4,
The driving waveform is configured in a non-linear form in all sections except the constant velocity section.
In claim 6,
The driving waveform has a non-linear form in which the slope of the voltage value increases in the acceleration section and has a non-linear form in which the slope of the voltage value decreases in the deceleration section.

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