Driver for driving a moving part of a laser radar, control method thereof, laser radar, and terminal device

Abstract

The present disclosure relates to a driver for driving a moving component of a laser radar, a control method thereof, the laser radar, and a terminal device. The driver includes a rotor, a stator, and a code disc. The rotor can move around an axis. The moving component is disposed on the rotor. The stator includes an electromagnetic member. The electromagnetic member can drive the rotor to move. The code disc can determine a rotation angle of the rotor. The driver is configured to output a quadrature-axis current to the electromagnetic member. The driver is configured to output a direct-axis current to the electromagnetic member within a time window. This can improve the temperature of the code disc. It helps to reduce or eliminate condensation / icing on the code disc.

Description

Technical Field

[0001] This disclosure relates to the field of photoelectric detection, and more specifically to a driver for driving moving parts of a lidar, a lidar, a terminal device, and a control method for the driver of a lidar. Background Technology

[0002] Lidar (Light Detection and Ranging) is a radar system that uses emitted laser beams to detect the position, velocity, and other characteristics of objects. Due to its advantages such as high resolution, strong resistance to active interference, good detection performance, small size, and light weight, lidar is widely used in fields such as autonomous driving, transportation communication, drones, intelligent robots, and resource exploration.

[0003] A lidar system comprises a laser emitting section and a signal receiving section. The light signal emitted by the lidar is reflected off an object, generating an echo. This echo is received by the signal receiving section and converted into an electrical signal. After demodulation, information such as distance can be obtained. Scanning lidar systems also include moving parts and actuators. The actuators drive the moving parts to change the direction of the laser, enabling one-dimensional or two-dimensional scanning. A code disk can be used in the actuator to measure the rotation angle of the moving parts. Under certain environmental conditions, water vapor may condense on the code disk, forming condensation or frost. Condensation or frost can affect the code disk's measurement of the rotation angle of the moving parts, thus affecting the lidar's performance. Summary of the Invention

[0004] This disclosure provides a driver for driving the moving parts of a lidar, which can increase the temperature of the code disk, thereby helping to reduce or eliminate condensation or frost on the code disk.

[0005] According to a first aspect of this disclosure, a driver is provided for driving a moving part of a lidar sensor. The driver includes: a rotor configured to move about an axis, the moving part being disposed on the rotor; a stator including an electromagnetic element configured to drive the rotor; and an encoder disk configured to determine a rotation angle of the rotor; the driver is configured to output a quadrature-axis current to the electromagnetic element; wherein the driver is configured to output a direct-axis current to the electromagnetic element within a time window.

[0006] Optionally, the time window includes a first time window, and the driver is configured to: within the first time window, make the direct-axis current and the quadrature-axis current satisfy a preset relationship.

[0007] Optionally, the preset relationship includes: the sum of the squares of the direct-axis current and the quadrature-axis current remains constant.

[0008] Optionally, the length of the first time window is adjustable.

[0009] Optionally, the time window includes a second time window, and the driver is configured to gradually increase the direct-axis current within the second time window.

[0010] Optionally, the time window includes a third time window, and the driver is configured to gradually reduce the direct-axis current within the third time window.

[0011] Optionally, the moving component includes a rotating mirror or rotating bracket of the lidar, and the moving component is configured to rotate about the axis.

[0012] Optionally, the driver is configured to output a constant direct-axis current to the electromagnetic element.

[0013] Optionally, the moving component includes a pendulum mirror or a galvanometer mirror, and the moving component is configured to reciprocate about the axis.

[0014] Optionally, when the rotor is in the equilibrium position, the direct-axis current has a first value; and when the rotor is in the maximum rotation angle, the direct-axis current has a second value, wherein the first value is greater than the second value.

[0015] Optionally, the electromagnetic component includes a core and a coil wound around the core.

[0016] Optionally, the driver further includes a controller configured to control the driver to output the direct-axis current to the electromagnetic component within the time window under preset conditions.

[0017] Optionally, the preset conditions include preset scenarios, temperature conditions, control commands, or the determination that condensation / frost exists on the encoder.

[0018] Optionally, the driver further includes a code reader configured to detect the code disk to determine the rotation angle of the rotor.

[0019] Optionally, the controller is configured to adjust the direct-axis current of the electromagnetic component based on the rotation angle of the rotor.

[0020] According to a second aspect of this disclosure, a lidar is provided, including a moving part and a driver as described above. The driver is configured to drive the moving part.

[0021] According to a third aspect of this disclosure, a terminal device is provided, including the lidar described above.

[0022] According to a fourth aspect of this disclosure, a control method for a driver of a lidar is provided. The control method includes outputting a quadrature-axis current to an electromagnetic component to drive a rotor to rotate; and outputting a direct-axis current to the electromagnetic component within a time window.

[0023] Optionally, the time window includes a first time window, and the control method further includes: within the first time window, ensuring that the direct-axis current and the quadrature-axis current satisfy a preset relationship.

[0024] Optionally, the preset relationship includes: the sum of the squares of the direct-axis current and the quadrature-axis current remains constant.

[0025] Optionally, the control method further includes: adjusting the length of the first time window.

[0026] Optionally, the time window includes a second time window, and the control method further includes: gradually increasing the direct-axis current within the second time window.

[0027] Optionally, the time window includes a third time window, and the control method further includes: gradually reducing the direct-axis current within the third time window.

[0028] Optionally, the control method further includes: outputting a constant direct-axis current to the electromagnetic component.

[0029] Optionally, the control method further includes: when the rotor is in the equilibrium position, giving the direct-axis current a first value; and when the rotor is in the maximum rotation angle, giving the direct-axis current a second value, wherein the first value is greater than the second value.

[0030] Optionally, the step of outputting the direct-axis current to the electromagnetic component within the time window is in response to satisfying a preset condition.

[0031] Optionally, the preset conditions include preset scenarios, temperature conditions, control commands, or the determination that condensation / frost exists on the encoder.

[0032] The driver disclosed herein can output direct-axis current to the electromagnetic component within a time window, which can increase the temperature of the code disk. Heating the code disk can help reduce or eliminate condensation / frost on the code disk, effectively addressing the impact of condensation / frost on the performance of the lidar. Furthermore, the driver disclosed herein can simultaneously achieve both motion control and code disk heating functions, and code disk heating can be performed using existing hardware circuitry without incurring additional costs. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be introduced as examples below. The drawings described below are merely embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort. The drawings are used to provide a further understanding of this disclosure and constitute a part of the specification. They are used together with the embodiments of this disclosure to explain this disclosure and do not constitute a limitation of this disclosure. In the drawings:

[0034] Figure 1 An example structural block diagram of an exemplary lidar consistent with some embodiments of this disclosure is shown.

[0035] Figure 2 A structural block diagram of an exemplary vehicle system consistent with some embodiments of this disclosure is shown.

[0036] Figure 3 A schematic structural diagram of a scanning device for lidar, consistent with some embodiments of the present disclosure, is shown.

[0037] Figure 4 An exemplary schematic diagram of the direct-axis current within a second time window, consistent with some embodiments of this disclosure, is shown.

[0038] Figure 5 An exemplary schematic diagram of the direct-axis current within a third time window, consistent with some embodiments of this disclosure, is shown.

[0039] Figure 6 An exemplary schematic diagram showing the variation of direct-axis current and rotation angle over time, consistent with some embodiments of this disclosure, is shown.

[0040] Figure 7 A flowchart of a control method for a driver for a lidar, consistent with some embodiments of this disclosure, is shown.

[0041] Figure 8 An exemplary schematic diagram showing the variation of cross-axis current and rotation angle over time, consistent with some embodiments of this disclosure, is shown. Detailed Implementation

[0042] The embodiments of this disclosure will be described below. It should be noted that, in order to provide a concise description of these embodiments, this specification cannot exhaustively describe all features of the actual embodiments. It should be understood that, in the actual implementation of any embodiment, changes may occur from one embodiment to another to achieve specific objectives. Furthermore, it is also understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content of this disclosure, some design, manufacturing, or production modifications based on the technical content disclosed in this disclosure are merely conventional technical means and should not be construed as insufficient content of this disclosure.

[0043] Unless otherwise defined, the technical or scientific terms used in the claims and description shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar words used in this patent application description and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms “an” or “a” and similar words do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar words mean that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. The terms “connected,” “coupled,” or “linked” and similar words are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0044] Unless otherwise specified, all embodiments mentioned herein can be combined to form new technical solutions. Furthermore, unless otherwise specified, all technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0045] In this disclosure, the terms "or" and "and / or" describe the relationship between related objects and indicate a non-exclusive inclusion. For example, "A and / or B" and "A or B" can include: the presence of only "A", the presence of only "B", and the presence of both "A" and "B", where "A" and "B" can be singular or plural. As another example, "A, B, and / or C" and "A, B, or C" can include: the presence of only "A", the presence of only "B", the presence of only "C", the presence of both "A" and "B", the presence of both "A" and "C", the presence of both "B" and "C", and the presence of both "A", "B", and "C", where "A", "B", and "C" can be singular or plural. Furthermore, the symbol " / " in this disclosure indicates an "or" relationship between the related objects before and after the symbol. In this disclosure, the term "at least one A or B" has the same meaning as "A or B" described above. The term "at least one A, B or C" has the same meaning as "A, B or C" above.

[0046] LiDAR (Light Detection and Ranging) is a remote sensing technology. LiDAR uses lasers to measure distances and create three-dimensional (3D) images of objects and landscapes. During object detection, the LiDAR emits a laser beam. The laser beam is reflected from the object's surface upon encountering it. The reflected light (also called the echo) is received by the LiDAR and converted into an electrical signal. The LiDAR processes this electrical signal to determine information about the object, such as its distance, position, or velocity. The LiDAR system 110 can also be configured to create a real-time 3D model of the environment, which can be represented as a point cloud. A point cloud can be a collection of 3D data points representing the surfaces of objects, structures, and the environment within a specific area. Each data point in the point cloud can be defined by its X, Y, and Z coordinates in space, representing its position in 3D space. Using point clouds, vehicles can accurately identify the positions of objects on the road, such as cars, pedestrians, and / or cyclists.

[0047] In some examples, LiDAR can generate point clouds, which simplifies and simplifies the processing of driver assistance algorithms. LiDAR can provide vehicles (such as intelligent vehicles) with high-resolution 3D perception, enhancing their perception capabilities to handle more complex road conditions (such as dark environments or unknown objects on highways). LiDAR can further provide high-performance automotive-grade LiDAR solutions, ensuring safer and smarter driver assistance, such as L2+ assisted driving. When configured, LiDAR can be widely used in passenger cars and commercial vehicles equipped with advanced driver assistance systems (ADAS) and / or autonomous driving (e.g., automated traffic). LiDAR can also be applied to any suitable end device, such as drones or robots. For example, LiDAR can support robotic applications such as delivery robots and logistics robots.

[0048] In some examples, LiDAR can be a long-range LiDAR sensor with a long detection range, such as from hundreds of meters to thousands of meters. Long-range LiDAR sensors can detect and classify objects at long distances. They can be mounted on the roof of a vehicle (e.g., the front and / or rear roof) to provide an unobstructed view of the road ahead and / or behind, and to detect objects at greater distances. This is extremely useful for highway driving and for detecting distant objects as early as possible.

[0049] In some examples, LiDAR can be a short-range LiDAR sensor with a short detection range, such as a few meters to tens of meters around the LiDAR, and a wide field of view (FOV), such as 60 degrees to 360 degrees horizontally. Short-range LiDAR sensors can detect objects at close range and provide a more comprehensive view of the surrounding environment / objects. Short-range LiDAR sensors can be mounted near or to the side of the vehicle's headlights to improve perception capabilities and assist in lane keeping and / or lane changing, parking, and other maneuvers.

[0050] In some examples, the lidar can be a mid-range lidar sensor. Mid-range lidar sensors strike a balance between long-range and short-range lidar sensors in terms of detection range (e.g., from a few meters to several hundred meters) and field of view (e.g., from 30 degrees to 180 degrees horizontally). Mid-range lidar sensors can be mounted on the front bumper, side panels, or rear bumper to detect objects near the vehicle.

[0051] In some examples, a lidar system with multiple lidar sensors is deployed around the vehicle. These multiple lidar sensors can be configured to have different detection ranges and fields of view to cover the area around the vehicle. In some embodiments, the lidar system includes one or more of a near-range lidar sensor, a mid-range lidar sensor, and a long-range lidar sensor. By combining lidar sensors at different locations on the vehicle, the lidar system can provide a comprehensive view of the environment. Data from these lidar sensors can be processed with data from other sensors, such as cameras and / or millimeter-wave radar, to make real-time decisions for safe and efficient autonomous driving. The combination of lidar sensors with different detection ranges, fields of view, and locations allows for a balance between long-range visibility and near-range object detection, while also considering aesthetics and cost.

[0052] In some examples, multiple lidar sensors are activated in a lidar system. In some embodiments, multiple lidar sensors are activated or deactivated depending on different scenarios or requirements. For example, when the vehicle is traveling at high speeds (e.g., above 40 mph), one or more short-range lidar sensors may be deactivated, while one or more long-range and / or mid-range lidar sensors may be activated. As another example, when the vehicle is traveling at lower speeds (e.g., below 40 mph), one or more long-range lidar sensors may be deactivated, while one or more short-range and mid-range lidar sensors may be activated. This effectively saves energy and extends the lifespan of the lidar system.

[0053] Figure 1 An example structural block diagram of an exemplary lidar consistent with some embodiments of this disclosure is shown. In some examples, reference is made to... Figure 1 The lidar 100 includes a laser emitting system 110, a laser receiving system 120, and a control and processing system 130. Optionally, the lidar 100 also includes a scanning system 140. The scanning system 140 may include a rotating optomechanical system, a rotating mirror, a reciprocating oscillating mirror or galvanometer (e.g., a MEMS mirror, a Galvo mirror, etc.), and other components that can direct the laser beam to different directions in the environment (e.g., prisms, gratings, diffractive optical elements, etc.).

[0054] In some examples, the laser emitting system 110 can emit a laser. When the laser encounters an object 10, it is reflected from the surface of the object 10, forming an echo. The echo returns to the lidar 100. The laser receiving system 120 can receive the reflected echo and convert it into an electrical signal. This electrical signal is pre-processed to determine echo data, such as the echo reception time, and provided to the control and processing system 130. The control and processing system 130 processes the echo data to determine information about the object 10, such as its distance, position, or velocity. Repeating this process multiple times can create an accurate, real-time 3D environment map, such as a point cloud. Computers in terminal devices such as vehicles can then perform safe navigation based on this point cloud.

[0055] In some examples, the laser emitting system 110 includes a driving circuit, a laser, and emitting optics. The laser emits laser light under the drive of the driving circuit, and the laser light exits through the emitting optics. In some embodiments, the laser may include a semiconductor laser, such as a vertical-cavity surface-emitting laser (VCSEL), an edge-emitting laser (EEL), or other semiconductor lasers capable of generating laser light. In other embodiments, the laser may also include a fiber laser. The laser emits laser light at a wavelength of 905 nm, 940 nm, or 1550 nm, and may also emit laser light at other wavelengths. The driving circuit may include a driver integrated circuit, such as an analog chip or a digital-analog hybrid chip.

[0056] In some examples, the laser receiving system 120 includes receiving optics and a receiver. The receiving optics collects the echo reflected from an object and focuses the echo onto the receiver. The receiver uses the photoelectric effect to convert the echo into an electrical signal. In some embodiments, the receiver may include a single-photon detector, such as an avalanche photodiode (APD), a single-photon avalanche diode (SPAD), or a silicon photomultiplier (SiPM). The lidar 100 may also include preprocessing circuitry. This preprocessing circuitry may include digitization circuitry, such as an analog-to-digital converter (ADC), to convert analog signals into digital signals for use with the control and processing system 130. Alternatively, the preprocessing circuitry may include a time-to-digital converter (TDC). The echo is detected and converted into an electrical signal by the receiver, which is then provided to the TDC. Based on the received electrical signal, the TDC can determine the timing information (e.g., a timestamp) of the echo and convert the timing information into a digital signal for use with the control and processing system 130. The preprocessing circuit may also include analog front-end circuitry for channel selection and analog signal amplification. In some embodiments, the preprocessing circuit may be implemented as a system-on-chip (SOC) or an application-specific integrated circuit (ASIC). The transmitting and receiving optics include, for example, one or more optical components such as lenses / lens groups, mirrors, filters, beam splitters, apertures, and homogenizers. The transmitting and receiving optics may be independently configured or may be wholly or partially multiplexed. For example, the transmitting and receiving optics may include at least one of a common lens, a common lens group, a common mirror, a common aperture, and a common beam splitter. The laser emitted by the laser and the echo reflected by the object may pass through at least one of the common lens, a common lens group, a common mirror, a common aperture, and a common beam splitter.

[0057] In some examples, the control and processing system 130 may include an information processing circuit and a light source control circuit. The information processing circuit processes electrical signals to determine information about the object. For example, the information processing circuit may include circuits implemented using an ASIC or a programmable logic device (PLD), such as a field-programmable gate array (FPGA), a microcontroller unit (MCU), or a digital signal processor (DSP). Alternatively, the information processing circuit may include a central processing unit (CPU). The light source control circuit sends control signals to the excitation source to control the excitation source to drive the laser to emit light, achieving pulsed laser emission. For example, the light source control circuit may send timing signals to control the laser emission timing. Furthermore, the light source control circuit may control one or more of the pulse interval, pulse intensity, and pulse width. Adding pulse coding functionality can enhance the anti-interference capability of the lidar. Optionally, the light source control circuit and the information processing circuit may be integrated together, for example, integrated into a main control chip, or they may be separate or partially separate chips. In some embodiments, when the lidar 100 includes a scanning system 140, the control and processing system 130 may further include a scanning control circuit for controlling the scanning system. The scanning control circuit may be integrated with one or all of the light source control circuit and the information processing circuit; for example, the scanning control circuit, the light source control circuit, and the information processing circuit may be integrated into a main control chip; or they may each be independent or partially independent chips. In some embodiments, the control and processing system 130 may be implemented in the form of a System-on-Chip (SoC) or an Application-on-ASIC (ASIC).

[0058] In some examples, lidar can be installed on terminal devices to transmit the detected sensing data. The terminal devices can then utilize this sensing data to perform one or more functions, such as analysis, decision-making, or control. Examples of terminal devices include vehicles, ships, aircraft (e.g., flying vehicles or drones), and robots (e.g., industrial robots or home robots).

[0059] Figure 2 A structural block diagram of an exemplary vehicle system consistent with some embodiments of this disclosure is shown. In some examples, reference is made to... Figure 2The vehicle system 200 includes a sensor system 202, a perception system 204, a planning system 206, and a control system 208. The vehicle system 200 may possess autonomous capabilities, for example, having at least one function, characteristic, device, and / or similar device that enables the vehicle to operate partially or fully without human intervention, including but not limited to fully autonomous vehicles (e.g., abandoning vehicles dependent on human intervention), highly autonomous vehicles (e.g., abandoning vehicles dependent on human intervention in certain situations), and / or similar devices. The sensor system 202 includes one or more devices, such as lidar 202a, radar 202b, camera 202c, sonar 202d, global positioning system (GPS) 202e, and inertial measurement unit (IMU) 202f. Lidar 202a may include lidar sensors, such as long-range lidar sensors, mid-range lidar sensors, or short-range lidar sensors. In some embodiments, the sensor system 202 may use one or more devices included in the sensor system 202 to generate environment-related data. The data generated by the sensor system 202 can be used by one or more systems to observe the environment in which the vehicle is located.

[0060] In some examples, the perception system 204 can receive data associated with objects in the environment and classify those objects. In some examples, the perception system 204 can receive image data (e.g., point clouds) associated with objects captured by a lidar system. In such examples, the perception system 204 can classify objects based on groupings of objects (e.g., bicycles, vehicles, traffic signs, pedestrians, and / or similar objects). In some embodiments, the perception system 204 can transmit data related to object classification to the planning system 206.

[0061] In some examples, the planning system 206 may receive destination-related data and generate route or trajectory-related data. A vehicle may then travel along this route or trajectory towards its destination. In some embodiments, the planning system 206 may periodically or continuously receive data from the sensing system 204 and update the route or trajectory based on the data generated by the sensing system 204.

[0062] In some examples, control system 208 can receive trajectory-related data from planning system 206, and control system 208 can control the operation of the vehicle. In some embodiments, control system 208 includes steering control system 208a and powertrain control system 208b. Control system 208 can control the operation of steering control system 208a and powertrain control system 208b according to the received trajectory. In some embodiments, powertrain control system 208b can receive control signals from control system 208 to start, stop, accelerate, decelerate, turn left, turn right, or perform similar operations on the vehicle. Steering control system 208a can receive control signals from control system 208 to turn one or more wheels of the vehicle. In some examples, when the trajectory includes a left turn, control system 208 transmits control signals to cause steering control system 208a to adjust the direction.

[0063] According to some embodiments of this disclosure, a driver is provided for driving a moving component of a lidar. The driver includes a rotor, a stator, and a code disk. The rotor is movable about an axis. A moving component is disposed on the rotor. The stator includes an electromagnetic element. The electromagnetic element can drive the rotor to move. The code disk can determine the rotation angle of the rotor. The driver can output a quadrature-axis current to the electromagnetic element. The driver can also output a direct-axis current to the electromagnetic element within a time window. In some embodiments, the moving component may include a mirror for reflecting at least one of a probe light and an echo. The mirror can be driven by the driver to rotate about an axis, thereby changing the emission angle of the probe light or the reception angle of the echo, scanning the field of view of the lidar. For example, the moving component may include a rotating mirror, a tilting mirror, or a galvanometer mirror. In some embodiments, the moving component may include a rotating bracket for supporting an optomechanical system. The rotating bracket can be driven by the driver to rotate about an axis, thereby driving the optomechanical system to rotate.

[0064] See Figure 3 The diagram illustrates a schematic structural design of a scanning device for lidar that is consistent with some embodiments of this disclosure. For example, the scanning device may be as follows: Figure 1 The scanning system 140 shown.

[0065] In some embodiments, the scanning device may include a moving component 20 and a driver 300. The moving component 20 may be mounted on the driver 300 and driven by the driver 300 to rotate about an axis. The driver 300 may include a stator 310 and a rotor 320. The rotor 320 may move about an axis. The moving component 20 may be disposed on the rotor 320. For example, the rotor may be configured to surround the stator and be capable of moving around the stator. Alternatively, the rotor may be disposed inside the stator. Figure 3The embodiment described herein uses a rotor 320 arranged to surround a stator 310 as an example, but the present disclosure is not limited thereto. The stator 310 may include an electromagnetic component. This electromagnetic component can drive the rotor 320 to move. By controlling the change in current in the electromagnetic component to generate a change in the magnetic field, the rotor 320 can be driven to move relative to the stator 310. During the movement of the rotor 320, the moving component 20 can be driven to move synchronously.

[0066] In some embodiments, the driver 300 can drive the moving part 20 to reciprocate within a specific angular range. Figure 3 In this embodiment, the rotor 320 can be in a balanced position relative to the stator 310 (i.e., Figure 3 (As shown in the image). The rotor 320 is capable of oscillating back and forth within a specific angular range on either side of the equilibrium position. This is described in detail below.

[0067] In some embodiments, the stator 310 may include an optional first magnetic element 311. The rotor 320 includes an optional second magnetic element 321. The first magnetic element 311 and the second magnetic element 321 can interact with each other. For example, the first magnetic element 311 and the second magnetic element 321 repel each other, causing the rotor 320 to return to the equilibrium position when it deviates from the equilibrium position by a certain angle. This allows the rotor 320 to drive the motion component 20 to reciprocate around the equilibrium position at a specific frequency and angular range. For example, the motion component 20 reciprocating about an axis may include a swivel mirror or galvanometer of a lidar.

[0068] In some embodiments, the driver 300 may include a stator 310 and a rotor 320 rotatable about an axis. The stator 310 can move the rotor 320 from an equilibrium position. A first magnetic element 311 and a second magnetic element 321 interact to return the rotor 320 to the equilibrium position. For example, the driver 300 may include, Figure 3 The illustrated 2-pole brushless DC motor. Those skilled in the art will understand that the number of pole pairs can be increased, or the driver 300 can include any drive structure capable of moving the rotor 320 relative to the stator 310.

[0069] by Figure 3Taking the driver 300 shown as an example, the rotor 320 may include a rotor body portion 32. The rotor body portion 32 can move about an axis, for example, by reciprocating about an axis. The stator 310 may include a stator body portion 31. The rotor body portion 32 may be disposed outside the stator body portion 31 so that the moving component 20 can be directly connected to the rotor body portion 32. It will be readily understood by those skilled in the art that the rotor body portion 32 may also be disposed inside the stator body portion 31, for example, by means of an extension structure to connect the moving component 20 to the rotor body portion 32 and move with the rotor body portion 32. The stator body portion 31 and the rotor body portion 32 cooperate with each other so that the rotor can move from the equilibrium position. In this embodiment, the second magnetic element 321 is connected to the rotor body portion 32, and the second magnetic element 321 interacts with the first magnetic element 311 to drive the rotor body portion 32 back to the equilibrium position.

[0070] In some embodiments, the stator 310 may further include an electromagnetic component. The electromagnetic component may include a core 313 and a coil 312 wound around the core 313. For example, the core 313 may be an iron core. When the coil 312 is energized, it generates a magnetic field. Changing the magnitude or direction of the current within the coil 312 can produce a change in the magnetic field. The rotor may further include a third magnetic component 322. The third magnetic component 322 is driven to move in the changing magnetic field, thereby driving the rotor 320 to move relative to the stator 310 from its equilibrium position. Figure 3 N and S in the text represent, for example, the polarity of the magnetic component. When coil 312 is energized, for example, when the positive and negative terminals of coil 312 are in... Figure 3 In the state shown, the N pole of the generated magnetic field points towards the direction of the second magnetic component 321, and the rotor 320 experiences a clockwise torque. When the positive and negative poles of the coil 312 are in the same direction as... Figure 3 Conversely, as shown, the rotor 320 is subjected to a counterclockwise torque, meaning that the stator 310 can cause the rotor 320 to move away from its equilibrium position.

[0071] exist Figure 3In this embodiment, when the rotor 320 moves from the equilibrium position relative to the stator 310, the first magnetic element 311 remains fixed, while the second magnetic element 321 moves with the rotor. The distance between the first magnetic element 311 and the second magnetic element 321 approaches (or moves away from) each other. The kinetic potential energy of the rotor 320 is absorbed by the magnetic field between the first magnetic element 311 and the second magnetic element 321, forming a spring-like structure. Its mechanical model can be considered as a spring element (or simply a magnetic spring) within a certain range. When the rotor 320 moves to its limit position, the potential energy accumulation of the magnetic spring reaches its limit. Releasing the potential energy can cause the rotor 320 to turn and return to the equilibrium position. By setting parameters such as the magnitude of the magnetic force between the first magnetic element 311 and the second magnetic element 321 and their distance, the stroke of the rotor 320, i.e., the swing angle range of the rotor 320 relative to the stator 310, can be set, thereby enabling the moving part 20 to move within a specific angle range. It should be noted that... Figure 3 The following description uses the example of the actuator 300 driving the moving part 20 to reciprocate, but the present disclosure is not limited thereto. In some embodiments of the present disclosure, the actuator 300 drives the moving part 20 to rotate about an axis in one direction.

[0072] In some embodiments, the driver may further include an encoder disk (not shown). The encoder disk can be used to determine the rotation angle of the rotor. The encoder disk may be disposed on the stator or the rotor. Optionally, the encoder disk may be in indirect or direct contact with the stator. Alternatively, the encoder disk may be in indirect or direct contact with the rotor.

[0073] In the dq coordinate system of the driver, the current applied to the electromagnetic component (e.g., the drive coil) can be decomposed into q-axis current (also referred to as quadrature-axis current) and d-axis current (also referred to as direct-axis current). The quadrature-axis current can provide driving force for the moving component. In some lidar systems, the direct-axis current does not provide the torque to rotate the moving component, so it is typically kept at zero or near zero, and only the quadrature-axis current is output to the electromagnetic component to reduce power consumption. In contrast, in some embodiments of this disclosure, the driver can output direct-axis current to the electromagnetic component (e.g., coil 312) within a time window. This direct-axis current can generate heat in the electromagnetic component to increase the temperature of the code disk. Heating the code disk can help reduce or eliminate condensation / frost on the code disk.

[0074] In some embodiments, the driver can simultaneously achieve motion control and encoder heating by controlling the current transmitted to the electromagnetic components of the stator, and encoder heating can be performed using existing hardware circuitry without incurring additional costs.

[0075] In some embodiments, the stator's electromagnetic components (e.g., coils) may have non-zero quadrature-axis currents to apply a driving force to the rotor. This allows the driver to drive the moving parts.

[0076] In some embodiments, the driver can output a direct-axis current to the electromagnetic component within a time window. Optionally, the driver can output a direct-axis current to the electromagnetic component throughout the entire movement of the moving part. Optionally, the driver can output a direct-axis current to the electromagnetic component during a portion of the movement process of the moving part. Optionally, the time window can be a period of time during which the code disk temperature needs to be increased. The time window can be determined based on the operating conditions of the lidar or environmental information. For example, the time window can be a period of time after the lidar is powered on. Another example is a period of time after the lidar detects condensation / frost on the code disk. Yet another example is a period of time after the ambient temperature of the lidar rapidly changes from a lower temperature to a higher temperature. Optionally, the length of the time window can be fixed or adjustable. For example, the length of the time window can be determined based on the degree of condensation / frost. Yet another example is a period of time determined based on the ambient temperature.

[0077] In some embodiments, the time window may include a first time window. Optionally, within the first time window, the driver may output a constant direct-axis current to the electromagnetic component, or the driver may output a varying direct-axis current to the electromagnetic component. Optionally, within the first time window, the direct-axis current transmitted to the electromagnetic component may be related to the value of the quadrature-axis current. For example, within the first time window, the driver may ensure that the direct-axis current and the quadrature-axis current satisfy a preset relationship. For example, the value of the direct-axis current may be kept constant with the sum of the values ​​of the quadrature-axis currents. For example, the value of the direct-axis current may be inversely proportional to the value of the quadrature-axis current. For example, when the quadrature-axis current increases, the direct-axis current decreases; when the quadrature-axis current decreases, the direct-axis current increases. Furthermore, the sum of the squares of the direct-axis current and the quadrature-axis current may be kept constant. Constantness may include complete constantness and substantial constantness. For example, the relationship between the direct-axis current and the quadrature-axis current may be expressed as: i d i represents the normalized direct-axis current. q This represents the normalized direct-axis current. In the driver's dq coordinate system, the driver's drive current can be decomposed into direct-axis current components and quadrature-axis current components. Keeping the sum of the squares of the direct-axis and quadrature-axis currents constant helps the driver operate with a constant drive current. This provides uniform heating power and maintains low power consumption. Optionally, within multiple first time windows, the driver can output a direct-axis current conforming to the same curve to the electromagnetic component; or, within multiple first time windows, the driver can output a direct-axis current conforming to different curves to the electromagnetic component. For example, the direct-axis current can be determined based on the operating conditions of the lidar or environmental information in different first time windows.

[0078] In some embodiments, the length of the first time window is adjustable. The first time window may correspond to the main cycle in which the driver heats the code disk. The length of the first time window can be adjusted based on the actual operating conditions of the LiDAR. The length of the first time window can be adjusted based on at least one of the severity of condensation / frost on the code disk, the ambient temperature of the LiDAR, and the application scenario of the LiDAR. For example, when condensation / frost is severe on the code disk, the length of the first time window can be longer; when condensation / frost is slight, the length of the first time window can be shorter. For example, when the LiDAR is in a relatively cold environment, the length of the first time window can be longer; when the LiDAR is in a relatively warm environment, the length of the first time window can be shorter.

[0079] In some embodiments, the time window may further include a second time window. Within the second time window, the driver may gradually increase the direct-axis current. See also Figure 4 The illustration shows an exemplary schematic diagram of the direct-axis current within a second time window, consistent with some embodiments of this disclosure. Within the second time window, the direct-axis current can increase from a first current value to a second current value, where the first current value can be greater than or equal to zero. This enables soft switching of the direct-axis current, avoiding the effects of sudden changes in the direct-axis current. For example, within the second time window, the direct-axis current can increase linearly with time, or it can increase non-linearly with time. For example, the slope of the increase in the direct-axis current and / or its relationship with time can be configured.

[0080] In some embodiments, the time window may further include a third time window. Within the third time window, the driver can gradually reduce the direct-axis current. See also Figure 5 The diagram illustrates an exemplary schematic of the direct-axis current within a third time window, consistent with some embodiments of this disclosure. Within the third time window, the direct-axis current can decrease from a third current value to a fourth current value, which can be greater than or equal to zero. This enables soft switching of the direct-axis current, avoiding the effects of sudden changes in the direct-axis current. For example, within the third time window, the direct-axis current can decrease linearly with time, or it can decrease non-linearly with time. For example, the slope of the direct-axis current decrease and / or its relationship with time can be configured.

[0081] In some embodiments, the time window may simultaneously include a second time window and a third time window. In some embodiments, the time window may include one of the second and third time windows. The durations of the second and third time windows may be the same or different. The curve of the direct-axis current increasing with time within the second time window may be the same as or different from the curve of the direct-axis current decreasing with time within the third time window. In some embodiments, a first time window may be included between the second and third time windows. Within the second time window, the direct-axis current may increase from a first current value to a second current value. Within the third time window, the direct-axis current may decrease from a third current value to a fourth current value. At the beginning of the first time window, the value of the direct-axis current may be the second current value. At the end of the first time window, the value of the direct-axis current may be the third current value. The second and third current values ​​may be the same or different.

[0082] In some embodiments, the time window may further include multiple second time windows. For example, within the multiple second time windows, the direct-axis current may increase with different curves. Alternatively, within the multiple second time windows, the direct-axis current may increase with the same curve. Multiple second time windows can achieve a staged increase in the direct-axis current.

[0083] In some embodiments, the time window may further include multiple third time windows. For example, within the multiple third time windows, the direct-axis current may decrease with different curves. Alternatively, within the multiple second time windows, the direct-axis current may decrease with the same curve. Multiple second time windows can achieve a staged decrease in the direct-axis current.

[0084] In some embodiments, the actuator can drive a moving part to rotate uniformly about an axis. The actuator can output a constant quadrature-axis current to the electromagnetic component to provide a constant driving force. The actuator can also output a constant direct-axis current to the electromagnetic component so that the actuator operates with a constant driving current. This provides uniform heating power. For example, the moving part rotating about an axis may include a rotating mirror or a rotating support of a lidar system.

[0085] In some embodiments, the driver can output a non-constant direct-axis current to the electromagnetic component. For example, the direct-axis current may have a first value when the rotor is in the equilibrium position. When the rotor is at its maximum rotation angle, the direct-axis current may have a second value. The first value may be greater than the second value. For example, the moving component may include a pendulum mirror, a galvanometer mirror, etc.

[0086] See Figure 6 The diagram illustrates an exemplary schematic showing the variation of direct-axis current and rotation angle over time, consistent with some embodiments of this disclosure. In this example, the rotation angle is defined as 0° when the rotor is in the equilibrium position. Figure 6 As shown, when the rotor is in the equilibrium position, the normalized direct-axis current id It can be between 0.9 and 1. The normalized direct-axis current i is when the rotor is at its maximum rotation angle (approximately ±30° in this example). d It can be between 0.1 and 0.5.

[0087] In some embodiments, the driver may further include a controller. The controller can control the driver to output direct-axis current to the electromagnetic component within a time window under preset conditions. Preset conditions may include preset scenarios, temperature conditions, control commands, or determination of condensation / frost on the encoder. For example, preset scenarios may include rainy or snowy weather conditions. For example, temperature conditions may include when the ambient temperature is lower than a preset temperature or when the rate of change of the ambient temperature is greater than a preset value. For example, control commands may include triggering an encoder heating command to output direct-axis current to the electromagnetic component when the driver starts. For example, control commands may also include sending a heating command to output direct-axis current to the electromagnetic component via a user interface when the operator detects a potential risk of condensation / frost or desires to heat the encoder. For example, the driver may also output direct-axis current to the electromagnetic component when condensation / frost is determined to exist on the encoder by a condensation / frost sensor or other condensation / frost detection method.

[0088] In some embodiments, the driver may further include a code reader. The code reader can detect the code disk to determine the rotation angle of the rotor. The code disk may be disposed on one of the stator and the rotor. The code reader may be disposed on the other of the stator and the rotor.

[0089] In some embodiments, the controller can also adjust the direct-axis current of the electromagnetic component based on the rotor's rotation angle. For example, in Figure 6 In one example, the controller can store the correspondence between the direct-axis current of the electromagnetic component and the rotation angle of the rotor, and adjust the direct-axis current of the electromagnetic component based on this correspondence. Alternatively, the controller can determine the direct-axis current of the electromagnetic component at different rotation angles based on the rotor's rotational speed at those angles.

[0090] According to another exemplary embodiment of this disclosure, a lidar is also provided.

[0091] A lidar system may include moving parts and actuators. Moving parts may include at least one of a rotating support, a rotating mirror, a tilting mirror, and a galvanometer. When a lidar system includes multiple moving parts, it may also include multiple actuators. One actuator drives one or more moving parts.

[0092] According to another exemplary embodiment of this disclosure, a terminal device is also provided. The terminal device may include the lidar described above.

[0093] In some embodiments, lidar can be installed on a terminal device to transmit the detected sensing data to the terminal device. The terminal device then uses the sensing data to perform one or more functions such as analysis, decision-making, or control. Terminal devices may include, for example, vehicles, ships, aircraft (e.g., flying vehicles or drones), and robots (e.g., industrial robots or home robots).

[0094] According to another exemplary embodiment of this disclosure, a control method for a driver of a lidar is also provided. The control method can be executed by a driver as described in any of the foregoing embodiments or a combination of any of the foregoing embodiments. Reference Figure 7 The diagram shows a flowchart of a control method 700 for a driver of a lidar, consistent with some embodiments of this disclosure. Figure 7 As shown, the control method 700 for the driver of a lidar may include the following steps S710 to S730.

[0095] In step S710, a quadrature-axis current is output to the electromagnetic component to drive the rotor to rotate.

[0096] In step S730, a direct-axis current is output to the electromagnetic component within a time window. This increases the temperature of the code disk. Heating the code disk helps reduce or eliminate condensation / frost on it.

[0097] Optionally, the driver can output direct-axis current to the electromagnetic component throughout the entire movement of the moving part. Optionally, the driver can output direct-axis current to the electromagnetic component during a specific time period of the moving part's movement. Optionally, the time window can be a period during which the code disk temperature needs to be increased. The time window can be determined based on the LiDAR's operating status or environmental information. For example, the time window can be the period after the LiDAR is powered on. Another example is the period after the LiDAR detects condensation / frost on the code disk. Yet another example is the period after the LiDAR's ambient temperature rapidly changes from a lower to a higher temperature. Optionally, the length of the time window can be fixed or adjustable. For example, the length of the time window can be determined based on the degree of condensation / frost. Yet another example is the length of the time window based on the ambient temperature.

[0098] refer to Figure 8 The illustration shows an exemplary schematic diagram of the variation of quadrature-axis current and rotation angle over time, consistent with some embodiments of this disclosure. This embodiment can be applied to method 700. Figure 3 Let's take the driver 300 as an example. In this example, when the rotor 320 is in the equilibrium position, the rotation angle can be defined as 0°. Figure 8 As shown, when rotor 320 is in the equilibrium position, the normalized quadrature-axis current i qIt can be between 0 and 0.3. When rotor 320 is at its maximum rotation angle (approximately ±30° in this example), the normalized quadrature-axis current i q It can be between -0.9 and -1 or between 0.9 and 1.

[0099] In some embodiments, the time window may include a first time window. Optionally, within the first time window, the driver may output a constant direct-axis current to the electromagnetic component, or the driver may output a varying direct-axis current to the electromagnetic component. Optionally, within the first time window, the direct-axis current transmitted to the electromagnetic component may be related to the value of the quadrature-axis current. For example, the control method 700 may further include: within the first time window, ensuring that the direct-axis current and the quadrature-axis current satisfy a preset relationship. For example, the value of the direct-axis current may be kept constant with the sum of the values ​​of the quadrature-axis currents. For example, the value of the direct-axis current may be inversely proportional to the value of the quadrature-axis current. For example, when the quadrature-axis current increases, the direct-axis current decreases; when the quadrature-axis current decreases, the direct-axis current increases. Furthermore, the sum of the squares of the direct-axis current and the quadrature-axis current may be kept constant. Constantness may include complete constantness and substantial constantness. For example, the relationship between the direct-axis current and the quadrature-axis current may be expressed as: Where i d i represents the normalized direct-axis current. q This represents the normalized direct-axis current. In the driver's dq coordinate system, the driver's drive current can be decomposed into direct-axis current components and quadrature-axis current components. Keeping the sum of the squares of the direct-axis and quadrature-axis currents constant helps the driver operate with a constant drive current. This provides uniform heating power and maintains low power consumption. Optionally, within multiple first time windows, the driver can output a direct-axis current conforming to the same curve to the electromagnetic component; or, within multiple first time windows, the driver can output a direct-axis current conforming to different curves to the electromagnetic component. For example, the direct-axis current can be determined based on the operating conditions of the lidar or environmental information in different first time windows.

[0100] In some embodiments, the control method 700 may further include adjusting the length of a first time window. The first time window may correspond to the main cycle in which the driver heats the code disk. The length of the first time window may be adjusted based on the actual operating conditions of the lidar. The length of the first time window may be adjusted based on at least one of the severity of condensation / frost on the code disk, the ambient temperature of the lidar, and the application scenario of the lidar. For example, when condensation / frost is severe on the code disk, the length of the first time window may be longer; when condensation / frost is slight, the length of the first time window may be shorter. For example, when the lidar is in a relatively cold environment, the length of the first time window may be longer; when the lidar is in a relatively warm environment, the length of the first time window may be shorter.

[0101] In some embodiments, the control method 700 may further include: gradually increasing the direct-axis current within a second time window. See also Figure 4 The diagram illustrates an exemplary schematic of the direct-axis current within a second time window, consistent with some embodiments of this disclosure. Within this second time window, the direct-axis current can increase from a first current value to a second current value, where the first current value can be greater than or equal to zero. This enables soft switching of the direct-axis current, avoiding the effects of sudden changes in the direct-axis current.

[0102] In some embodiments, the control method 700 may further include: gradually reducing the direct-axis current within a third time window. See also Figure 5 The diagram illustrates an exemplary schematic of the direct-axis current within a third time window, consistent with some embodiments of this disclosure. Within the third time window, the direct-axis current can decrease from a third current value to a fourth current value, which can be greater than or equal to zero. This enables soft switching of the direct-axis current, avoiding the effects of sudden changes in the direct-axis current.

[0103] In some embodiments, the control method 700 may further include: outputting a constant direct-axis current to an electromagnetic component. This can drive a moving part to rotate uniformly about an axis. In this regard, a constant quadrature-axis current can be output to the electromagnetic component to provide a constant driving force. In this case, outputting a constant direct-axis current to the electromagnetic component allows the driver to operate with a constant driving current. This can provide uniform heating power. For example, the moving part rotating about an axis may include a rotating mirror or a rotating support of a lidar.

[0104] In some embodiments, the control method 700 may further include: outputting a non-constant direct-axis current to an electromagnetic component. For example, when the rotor is in the equilibrium position, the direct-axis current has a first value. When the rotor is at its maximum rotation angle, the direct-axis current has a second value. The first value is greater than the second value. For example, the moving component may include a pendulum mirror, a galvanometer, etc.

[0105] See Figure 6 The diagram illustrates an exemplary schematic showing the variation of direct-axis current and rotation angle over time, consistent with some embodiments of this disclosure. In this example, the rotation angle can be defined as 0° when the rotor is in the equilibrium position. Figure 6 As shown, when the rotor is in the equilibrium position, the normalized direct-axis current i d It can be between 0.9 and 1. The normalized direct-axis current i is when the rotor is at its maximum rotation angle (approximately ±30° in this example). d It can be between 0.1 and 0.5.

[0106] In some embodiments, in step S730, the step of outputting direct-axis current to the electromagnetic component within a time window can be responsive to satisfying a preset condition. The preset condition may include a preset scenario, temperature conditions, control commands, or the determination that condensation / frost exists on the encoder. For example, a preset scenario may include rainy or snowy weather conditions. For example, temperature conditions may include when the ambient temperature is lower than a preset temperature or when the rate of change of the ambient temperature is greater than a preset value. For example, a control command may include triggering a encoder heating command to output direct-axis current to the electromagnetic component when the driver starts. For example, a control command may also include sending a heating command to output direct-axis current to the electromagnetic component via a user interface when the operator detects a potential risk of condensation / frost or desires to heat the encoder. For example, the driver may also output direct-axis current to the electromagnetic component when condensation / frost is determined to exist on the encoder by a condensation / frost sensor or other condensation / frost detection method.

[0107] This concludes the description of a driver for driving a moving part of a lidar, a lidar, a terminal device, and a control method for the lidar driver according to the present disclosure. Compared to lidar drivers that maintain the direct-axis current at zero or near zero, the driver of this disclosure can output direct-axis current to the electromagnetic component within a time window to increase the code disk temperature. Condensation / frost easily occurs when hot air encounters a cold object surface; increasing the code disk temperature can prevent condensation / frost formation on the code disk or accelerate the dissipation of condensation / frost at the code disk. This effectively solves the impact of condensation / frost on lidar performance. Furthermore, the driver of this disclosure can simultaneously achieve motion control and code disk heating functions, and code disk heating can be performed using existing hardware circuitry without incurring additional costs. This helps reduce the cost of lidar.

[0108] It should be understood that the above description is illustrative and not restrictive. For example, the above embodiments (and / or aspects thereof) can be used in combination with each other. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of the various embodiments of this disclosure without departing from the scope of this disclosure. While the dimensions and types of materials described herein are used to define parameters of the various embodiments of this disclosure, the embodiments are not intended to be restrictive but are exemplary. Many other embodiments will become apparent to those skilled in the art upon reading the above description. Therefore, the scope of the various embodiments of this disclosure should be determined by reference to the appended claims and the full scope of their equivalents.

Claims

1. A driver for driving a moving part of a lidar system, comprising: A rotor configured to move about an axis, wherein the moving parts are disposed on the rotor; A stator, the stator including an electromagnetic element configured to drive the rotor to move; as well as A code disk configured to determine the rotation angle of the rotor; The driver is configured to output a quadrature-axis current to the electromagnetic component. The driver is also configured to output a direct-axis current to the electromagnetic component within a time window.

2. The driver as claimed in claim 1, characterized in that, The time window includes a first time window, and the driver is configured to: within the first time window, make the direct-axis current and the quadrature-axis current satisfy a preset relationship.

3. The driver as claimed in claim 2, characterized in that, The preset relationship includes: the sum of the squares of the direct-axis current and the quadrature-axis current remains constant.

4. The driver as claimed in claim 2, characterized in that, The length of the first time window is adjustable.

5. The driver as claimed in claim 1, characterized in that, The time window includes a second time window and / or a third time window, and the driver is configured to: Within the second time window, the direct-axis current is gradually increased; and / or Within the third time window, the direct-axis current is gradually reduced.

6. The driver as claimed in claim 1, characterized in that, The driver is configured to output a constant direct-axis current to the electromagnetic component.

7. The driver as claimed in claim 1, characterized in that, When the rotor is in the equilibrium position, the direct-axis current has a first value; and When the rotor is at its maximum rotation angle, the direct-axis current has a second value, and the first value is greater than the second value.

8. The driver of claim 1, further comprising: A controller is configured to control the driver to output the direct-axis current to the electromagnetic component within the time window under preset conditions.

9. The driver as claimed in claim 8, characterized in that, The preset conditions include preset scenarios, temperature conditions, control commands, or the determination that condensation / frost exists on the encoder.

10. The driver of claim 8, further comprising: A code reader configured to detect the code disk to determine the rotation angle of the rotor; The controller is configured to adjust the direct-axis current of the electromagnetic component based on the rotation angle of the rotor.

11. A lidar, comprising: Moving parts; and One or more actuators as described in any one of claims 1-10 are configured to drive the moving part.

12. A terminal device comprising the lidar as described in claim 11.

13. A control method for a driver of a lidar system, the control method comprising: The electromagnetic component outputs a quadrature-axis current to drive the rotor to rotate; as well as Output direct-axis current to the electromagnetic component within the time window.

14. The control method as described in claim 13, characterized in that, The time window includes a first time window, and the control method further includes: within the first time window, ensuring that the direct-axis current and the quadrature-axis current satisfy a preset relationship.

15. The control method as described in claim 14, characterized in that, The preset relationship includes: the sum of the squares of the direct-axis current and the quadrature-axis current remains constant.

16. The control method as described in claim 13, characterized in that, The control method further includes: Within the second time window, the direct-axis current is gradually increased; and / or Within the third time window, the direct-axis current is gradually reduced.

17. The control method as described in claim 13, characterized in that, The control method further includes: outputting a constant direct-axis current to the electromagnetic component.

18. The control method as described in claim 13, characterized in that, The control method further includes: When the rotor is in the equilibrium position, the direct-axis current has a first value; and When the rotor is at its maximum rotation angle, the direct-axis current has a second value, and the first value is greater than the second value.

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