Laser radar and laser radar speed control method

Abstract

The invention relates to the technical field of laser radars, in particular to a laser radar and a laser radar speed control method. The laser radar comprises a light emitting assembly, a light receiving assembly, a rotating mirror, a motor and a controller, the light receiving assembly comprises an optical sensor, a light guide path is arranged between the optical sensor and the rotating mirror, the light emitting assembly can emit laser, and the rotating mirror can reflect the laser to the light guide path when rotating to a preset position. The laser is transmitted to the optical sensor, the optical sensor can receive a light spot signal of the laser, and the controller can obtain the actual rotating speed and the rotating angle of the rotating mirror through the light spot signal. The device utilization rate of the laser radar is high, the position of the rotating mirror is detected in the distance measuring process, the detection signal in the speed measuring process directly comes from the rotating mirror, and the light path of the light guide path is flexible and is not limited by the structure of the laser radar, so that the laser radar is suitable for most laser radar structures, and the application range is wider.

Description

Technical Field

[0001] The present application relates to the field of laser radar technology, and in particular to a laser radar and a laser radar speed control method. Background Art

[0002] Laser radar can be used to measure the distance of a target and is widely used in robots. Laser radar is mainly composed of four core components: laser, receiver, signal processing unit and rotating mechanism. Generally speaking, the speed control and rotation position measurement of the rotating mechanism require the use of common means such as code disks for detection, thereby forming a feedback closed-loop control and real-time mirror angle position data output. Existing ranging radars basically use code disks to achieve speed detection and speed control, which are costly, large in size and have a relatively complex structure. Summary of the invention

[0003] The implementation methods of the present application mainly solve the technical problems that the existing laser radar uses code disks and other means to detect rotation speed, which is costly and complex to control.

[0004] In order to solve the above technical problems, a technical solution adopted in the embodiment of the present application is: providing a laser radar, including a light emitting component, a light receiving component, a rotating mirror, a motor and a controller, wherein the light receiving component includes an optical sensor, and a light guide path is provided between the optical sensor and the rotating mirror;

[0005] The light emitting assembly is used to emit laser light to the rotating mirror;

[0006] The motor is used to drive the rotating mirror to rotate;

[0007] The rotating mirror is used to reflect the laser to the light guide path when rotating to a preset position, and transmit the laser to the optical sensor through the light guide path;

[0008] The optical sensor is used to receive the spot signal of the laser;

[0009] The controller is used to obtain the actual rotation speed and rotation angle of the rotating mirror through the light spot signal.

[0010] Optionally, the light receiving component further includes a light receiving lens;

[0011] The rotating mirror is used to reflect the laser to the surrounding environment when rotating to a non-preset position, and is also used to transmit part of the light diffusely reflected by the surrounding environment to the light receiving lens;

[0012] The light receiving lens is used to receive the light transmitted by the rotating mirror and provide it to the optical sensor.

[0013] Optionally, the rotating mirror is a double-sided reflecting mirror, so that when the rotating mirror rotates one circle, the optical sensor receives the light spot signal twice.

[0014] Optionally, the light guide path is an optical fiber or a light guide tube.

[0015] Optionally, the light path output position of the light guide path corresponds to a corner position of the optical sensor.

[0016] Optionally, the laser radar also includes a supporting frame, and the light emitting component and the light receiving component are fixedly arranged on the supporting frame, wherein the central axis of the light emitting component and the optical sensor are located in the same vertical plane, and the optical sensor is perpendicular to the central axis of the light emitting component.

[0017] Optionally, a laser collimation component is provided at at least one end of the light guide path, and the laser collimation component is used to improve the stability of the laser input and / or output of the light guide path.

[0018] In order to solve the above technical problems, another technical solution adopted in the embodiment of the present application is: to provide a laser radar speed control method, which is applied to the above-mentioned laser radar, and the method includes:

[0019] Determining a driving signal according to a desired rotation speed of the rotating mirror, wherein the driving signal is used to control the motor to drive the rotating mirror to rotate;

[0020] Acquire a light spot signal, and acquire an actual rotation speed and a rotation angle of the rotating mirror through the light spot signal;

[0021] A rotation speed feedback signal is determined according to the desired rotation speed and the actual rotation speed, and feedback adjustment is performed on the drive signal based on the rotation speed feedback signal.

[0022] Optionally, acquiring the light spot signal includes:

[0023] When the rotating mirror rotates to a preset position, it reflects the laser light to the optical path, and transmits the laser light to the optical sensor through the optical path;

[0024] The optical sensor receives the optical signal of the laser and converts the optical signal into an electrical signal, which is the light spot signal.

[0025] Optionally, acquiring the actual rotation speed and rotation angle of the rotating mirror through the light spot signal includes:

[0026] Acquire time information of receiving the light spot signal at least twice;

[0027] Calculate the actual rotation speed of the rotating mirror according to the time information;

[0028] The rotation angle of the rotating mirror is calculated according to the actual rotation speed.

[0029] Optionally, the driving signal is a PWM signal, and the feedback adjustment of the driving signal based on the speed feedback signal includes:

[0030] The duty cycle of the PWM signal is adjusted based on the speed feedback signal.

[0031] Different from the related art, the embodiment of the present application provides a laser radar and a laser radar speed control method. The laser radar includes a light emitting component, a light receiving component, a rotating mirror, a motor and a controller, wherein the light receiving component includes an optical sensor, wherein a light guide path is provided between the optical sensor and the rotating mirror, wherein the light emitting component can emit laser to the rotating mirror, and the rotating mirror can reflect the laser to the light guide path when rotating to a preset position, and transmit the laser to the optical sensor through the light guide path, and the optical sensor can receive the laser spot signal, and the controller can obtain the actual rotation speed and rotation angle of the rotating mirror through the spot signal. The laser radar has a high device utilization rate. The laser emitted by the laser transmitter is only used for speed measurement when the mirror rotates to a specific angle, and the rest of the positions are used for ranging and obstacle avoidance. The mirror position detection is also performed during the ranging process. Since the detection signal of the speed measurement process comes directly from the mirror itself, there is no structural installation error caused by traditional auxiliary detection methods such as photoelectric code disks. Moreover, the optical path of the optical guide path is flexible and not constrained by the structure of the laser radar. It is suitable for most laser radar structures and has a wider range of applications. Because both the detection and transmission sides are based on the laser light source and sensor of the radar main optical path, the detection data is more accurate, which can also save unit module space and reduce the cost of additional detection devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and the figures in the drawings do not constitute proportional limitations unless otherwise stated.

[0033] Figure 1 is a schematic diagram of the structure of a laser radar provided in an embodiment of the present application;

[0034] Figure 2 is a schematic diagram of the structure of a laser radar from another angle provided in an embodiment of the present application;

[0035] Figure 3 It is a flow chart of a laser radar speed control method provided in an embodiment of the present application;

[0036] Figure 4It is a block diagram of a dynamic structure system of a laser radar operation provided in an embodiment of the present application;

[0037] Figure 5 This is a block diagram of a laser radar transfer mirror driving system provided in an embodiment of the present application;

[0038] Figure 6 This is an example diagram of the laser radar operation process provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0040] It should be noted that, if there is no conflict, the various features in the embodiments of the present application can be combined with each other, all within the protection scope of the present application. In addition, although the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in an order different from that in the flow chart. Unless otherwise defined, all technical and scientific terms used in this specification are the same as the meanings generally understood by those skilled in the art of the present application. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not used to limit the present application. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0041] Laser radar determines the distance between the object and the test point by emitting a laser beam to the object, receiving the reflected wave of the laser beam, and recording the time difference. Among them, the distance measurement and speed measurement of laser radar are basic functions. In order to improve the user experience, we try to optimize the structure of laser radar and control the cost. However, we found the following technical problems: analyzing the speed measurement method of laser radar, the existing laser radar usually uses a photoelectric encoder to detect the rotation speed and control the speed. The photoelectric encoder occupies a large volume compared to laser radar, the cost is relatively high, and the photoelectric encoder sometimes needs to be calibrated, which is not convenient to use.

[0042] In view of the above technical problems, the present application embodiment provides a laser radar, please refer to Figure 1 and Figure 2 , the dotted line in the figure represents the laser light, Figure 1The schematic diagram of the structure of the approximate cross section of the laser radar from a top-down perspective is shown. The laser radar 100 includes a light emitting component, a light receiving component, a rotating mirror 12, a motor (not shown) and a controller (not shown). In some embodiments, the light emitting component may be a laser emitter 11, and the light receiving component may be an optical sensor 14. A light guide path 13 is provided between the optical sensor 14 and the rotating mirror 12, and the light emitting component and the light receiving component are fixedly provided on the support frame 10. The central axis of the light emitting component and the optical sensor 14 are located in the same vertical plane, and the optical sensor 14 is perpendicular to the central axis of the light emitting component. The rotating mirror 12 is controlled to rotate by a motor (not shown) so that the rotating mirror 12 rotates based on its central axis. The motor may use a belt, gear or other transmission method to drive the rotating mirror to rotate, which is not limited in the embodiments of the present application.

[0043] It is understandable that the description in this embodiment that the central axes of the light emitting component and the optical sensor are "located in the same vertical plane", and the central axes of the optical sensor and the light emitting component are "perpendicular", etc., are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0044] For details, please combine Figure 2 , Figure 2 This is a schematic diagram of the approximate cross-section of the laser radar from a normal viewing angle. It should be noted that: Figure 2 The dotted line is only used to facilitate the description of the transmission path of the laser. The laser transmitter 11 can emit laser light to the rotating mirror 12. The motor drives the rotating mirror 12 to rotate. When the rotating mirror 12 rotates to a preset angle, it can reflect the laser light to the optical path 13. Figure 2 It can be seen that the other end of the light guide path 13 is set corresponding to the receiving end of the optical sensor 14, and the rotating mirror 12 can also transmit the laser to the optical sensor 14 through the light guide path 13. The optical sensor 14 can receive the spot signal of the laser transmitted by the light guide path 13. The controller is electrically connected to the optical sensor 14, and the actual rotation speed and rotation angle of the rotating mirror 12 can be obtained through the spot signal. The controller is also electrically connected to the motor, and the rotation speed of the rotating mirror can be controlled by controlling the motor.

[0045] Existing rotating mirror laser radars generally work based on a fixed optical transceiver component and a rotating passive optical component (rotating mirror). The detection of the real-time speed and position of the rotating mirror is controlled by a functional unit that implements closed-loop speed control and angle position data output. The traditional detection method generally uses a set of auxiliary functional devices to achieve the above functions, such as optical code disks, electromagnetic Hall devices, etc. However, the detection accuracy of optical code disks or electromagnetic Hall devices is easily limited by the assembly and the detection device itself is a digital nonlinear device. There are many limitations such as limited detection accuracy and limited data information provided to the back-end algorithm.

[0046] Therefore, in order to solve the above problems, the laser radar provided in the embodiment of the present application can effectively reuse the space and time of the main optical transceiver components by means of a light-guiding path in combination with a rotating mirror, and simultaneously detect the position of the rotating mirror during the ranging process, so as to achieve accurate speed and position detection, so as to solve the above problems. Among them, the light-guiding path can be an optical fiber, a light pipe, or other suitable light-guiding path. In the embodiment of the present application, optical fiber is used as an example for explanation. Compared with the traditional photoelectric code disk speed measurement, the volume occupied by the optical fiber is small, and the shape is not easily restricted by the laser radar structure, and the application is more extensive. In this scheme, there is no need to change the optical transceiver unit component of the laser radar (including the original laser transmitter, rotating mirror and optical sensor). By utilizing the spatial relationship in the structural design of the optical transceiver unit component, a certain position is obtained as the optical path input point of the optical path during the laser reflection process by the rotating mirror, and the optical path output point of the optical path is obtained at a certain position in the non-main optical path of the optical receiving component, thereby forming a light spot signal of a periodic specific laser at a specific time and a specific space. At the same time, since this signal has a very large characteristic isolation from the normal optical signal of the laser ranging, the controller can easily separate the laser spot signal of the speed measurement optical fiber optical path, and it is also convenient to further improve the detection accuracy through algorithm processing.

[0047] The normal optical signal of laser ranging refers to the optical signal reflected by the rotating mirror received by the optical sensor when the laser radar is measuring the distance normally. Figure 2 As shown, the light receiving assembly also includes a light receiving lens 15, the central axis of the light receiving lens 15 is located in the same vertical plane as the central axis of the light emitting assembly 11 and the light receiving assembly 14, and the light receiving assembly 14 is perpendicular to the central axis of the light receiving lens 15. When the laser radar is used for ranging, the rotating mirror 12 reflects the laser to the surrounding environment when it is rotated to a non-preset position (in order to distinguish it from the description adopted by the above reflection to the light guide path), and transmits part of the light diffusely reflected by the surrounding environment to the light receiving lens 15; the light receiving lens 15 can receive the light transmitted by the rotating mirror 12 and provide it to the optical sensor 14, and the optical sensor 14 can perform laser radar ranging based on the information of these lights.

[0048] The light mentioned here is the normal light signal of laser ranging. It can be understood that compared with the light spot signal provided by the optical path to the optical sensor in the above-mentioned embodiment, there is a very large characteristic isolation between the two. Therefore, the controller can easily separate the light spot signal of the laser of the speed measurement optical fiber optical path, so as to obtain the actual rotation speed of the rotating mirror. In some embodiments, in order to reduce the influence of the light spot signal on the normal light signal of laser ranging, the light path output position of the optical path of the optical path can be set corresponding to the corner position of the optical sensor. It can be seen that in the laser radar provided in the embodiment of the present application, only the reflected light of the rotating mirror when it is rotated to a preset position is used for speed measurement, that is, the rotating mirror is only used for speed measurement when it is rotated to a specific angle, and the other rotation positions are used for conventional ranging and obstacle avoidance. Only one optical sensor is needed to complete the ranging function and speed measurement function of the laser radar.

[0049] In some embodiments, the rotating mirror is a double-sided reflector, based on which, each time the rotating mirror rotates a circle, the reflected light will pass through the optical fiber twice, and the optical sensor will receive the laser spot signal twice. The controller monitors the rotating speed of the rotating mirror in real time through the collected laser spot signal, and adjusts and controls the rotating speed of the rotating mirror in real time by real-time regulation of the motor. Specifically, the rotating mirror angle or position information can be obtained by iteratively calculating the spot characteristics of the optical fiber each time it returns to the receiving light sensor. Since the sampling spatial resolution of the optical sensor can be approximately 0.5 degrees per frame, the optical sensor will have at least three or more sampling data acquisitions for the high-brightness Gaussian spot signal transmitted back by the optical fiber, thereby confirming the peak point of the spot at that moment, thereby confirming the rotating mirror position at that moment, and then obtaining the rotating mirror angle or position information.

[0050] In some embodiments, at least one end of the light guide path is further provided with a laser collimation component. Taking the optical fiber as an example, optical devices such as laser collimation or light splitting are provided at both ends of the optical fiber, so that the spot signal of the input or output laser can be further optically processed according to the actual signal requirements, such as improving the stability of the laser input and / or output of the light guide path. Of course, if the current scenario does not require such processing, based on cost considerations, similar optical devices may not be added, and the complete optical fiber end face may be directly used as input or output.

[0051] The laser radar provided by the embodiment of the present application includes a light emitting component, a light receiving component, a rotating mirror, a motor and a controller, the light receiving component includes an optical sensor, and a light guide path is arranged between the optical sensor and the rotating mirror, wherein the light emitting component can emit laser to the rotating mirror, the rotating mirror can reflect the laser to the light guide path when rotating to a preset position, and transmit the laser to the optical sensor through the light guide path, the optical sensor can receive the spot signal of the laser, and the controller can obtain the actual rotation speed and rotation angle of the rotating mirror through the spot signal. The laser radar has a high device utilization rate, the laser emitted by the laser transmitter is only used for speed measurement when the rotating mirror rotates to a specific angle, and the remaining positions are used for distance measurement and obstacle avoidance. At the same time, the detection signal of the speed measurement process comes directly from the rotating mirror itself, and there is no structural installation error caused by traditional auxiliary detection methods (such as photoelectric code disks), and the light path of the light guide path is flexible and not constrained by the structure of the laser radar, and is suitable for most laser radar structures. Compared with the speed measurement structure of the photoelectric code disk, its application range is wider. In addition, the detection light signal transmitted from the rotating mirror through the optical path is applied to the light receiving component as a continuous detection signal, which not only reduces the error but also provides the possibility for the back-end algorithm to achieve error convergence.

[0052] The present application embodiment provides a laser radar speed control method, which is applied to the laser radar in the above embodiment. Figure 3 , the method comprising:

[0053] S11, determining a driving signal according to the expected rotation speed of the rotating mirror, wherein the driving signal is used to control the motor to drive the rotating mirror to rotate. The expected rotation speed of the rotating mirror refers to the rotation speed of the rotating mirror desired by the user, that is, the target rotation speed.

[0054] Please combine Figure 4 , Figure 4 is a block diagram of a dynamic structure system of a laser radar provided in an embodiment of the present application, in which w d is the expected speed, w s is the motor speed, w a is the actual mirror rotation speed, w c is the negative feedback sampling speed, U a is the PWM output voltage, U d is the interference voltage, U o is the voltage after considering the voltage disturbance.

[0055] The driving signal is determined according to the expected rotation speed of the rotating mirror, which refers to the expected rotation speed w d Determine the initial drive signal of the motor, which can be a PWM signal to facilitate subsequent feedback control. Figure 4, where G1 is the PWM adjustment link, which takes the error signal between the desired speed and the actual speed as input, and outputs the voltage signal as the motor drive signal after proportional calculation to adjust the motor. The expression of this link is G1=K1. It can be understood that w c is the negative feedback sampling speed. In the initial state, the motor has not started yet, its actual speed is 0, and the motor has not generated a speed feedback signal. The error signal is the drive signal corresponding to the expected speed. At this time, the drive signal is determined only by the expected speed of the rotating mirror, and the motor rotation is controlled by the drive signal. After the speed feedback signal is generated at least once, the drive signal will be affected by the feedback-related signal, that is, considering w c The generated driving signal adjusts the driving signal of the motor in real time.

[0056] For details, please combine Figure 4 , G2 is the mirror drive link, which uses the voltage signal output by PWM as the motor drive signal, that is, the input of the motor, to drive the motor to rotate. For the mirror drive system, in order to facilitate explanation, it is simplified to a brushless DC motor in this embodiment, and there is the following armature voltage balance equation:

[0057] T e =C t I a ;

[0058] E a =C e w s ;

[0059] Among them, T e is the output torque, C t is the torque coefficient, E a is the back electromotive force, C e is the electromotive force coefficient, w s is the output speed.

[0060] The torque balance equation is as follows:

[0061]

[0062] U o =I a R+E a .

[0063] The block diagram of the mirror drive system is as follows: Figure 5 As shown, its reference input U o The closed-loop transfer function under the action of (s) is as follows:

[0064]

[0065]

[0066] From the above analysis, it can be concluded that the transfer function expression of this link is as follows:

[0067]

[0068] G3 is the mirror rotation link. The mirror is driven by the motor of the previous link G2 to output the actual speed signal. The expression corresponding to this link is: G3=K3.

[0069] Please combine Figure 4 , G4 in the figure is the sampling fiber negative feedback link, which samples the laser spot signal through the fiber, and then processes the laser spot signal and its spot characteristics through the optical sensor to obtain the speed feedback signal. Its expression is: G4 = K4.

[0070] Specifically, S12, obtaining a spot signal, and obtaining the actual rotation speed and rotation angle of the rotating mirror through the spot signal. Wherein, obtaining the spot signal includes: when the rotating mirror rotates to a preset position, the laser is reflected to the optical path by the rotating mirror, and the laser is transmitted to the optical sensor through the optical path; then the optical sensor receives the optical signal of the laser, and converts the optical signal into an electrical signal, and the electrical signal is the spot signal. It can be understood that the transmission speed of the laser in the optical path is very fast. Therefore, it can be approximately understood that when the rotating mirror rotates to the preset position, the optical sensor can obtain the spot signal. In addition, the area of ​​the input end of the optical path is very small. During the rotation process, the time for the rotating mirror to reflect the laser to the optical path is very short, which can be approximately regarded as a moment.

[0071] Based on this, the actual rotation speed and rotation angle of the rotating mirror are obtained through the light spot signal. By obtaining the time information of receiving the light spot signal at least twice; calculating the actual rotation speed of the rotating mirror according to the time information; and calculating the rotation angle of the rotating mirror according to the actual rotation speed. It can be understood that, in the embodiment of the present application, taking a double-sided reflector as an example, assuming that the first light spot signal is received at moment a and the second light spot signal is received at moment b, then the time from moment b to moment a is the time for the rotating mirror to rotate 180 degrees, and the actual rotation speed of the rotating mirror can be calculated based on this. At the same time, the position of the rotating mirror corresponding to the moment when the light spot signal is received is known, because only when the rotating mirror rotates to the preset position can the optical sensor receive the light spot signal. Based on this, combined with the actual rotation speed of the rotating mirror, the rotation angle of the rotating mirror can be calculated.

[0072] In the process of the motor controlling the rotation of the rotating mirror according to the driving signal, the rotation speed of the rotating mirror can be indirectly calculated according to the rotation state of the motor. However, there may be errors in the calculated rotating mirror rotation speed. For example, it may be affected by interference factors such as the friction of the motor itself or the wear between the linkage parts, resulting in the actual rotation speed of the rotating mirror being different from the expected rotation speed that the user hopes to achieve through motor control. That is, the driving signal of the motor is determined according to the expected rotation speed, and the rotation of the motor is controlled according to this driving signal. In theory, the rotating mirror can be controlled to rotate at the expected rotation speed. However, due to the existence of interference factors, the actual rotation speed of the rotating mirror may not be the expected rotation speed. Therefore, it is necessary to feedback adjust the actual rotation speed of the rotating mirror according to the expected rotation speed and the actual rotation speed. To adjust the rotating mirror rotation speed, it is necessary to adjust the driving signal of the motor, thereby offsetting the influence of the interference factors and adjusting the actual rotation speed of the rotating mirror to the expected rotation speed.

[0073] Still Figure 4 Taking the schematic diagram of as an example, the above links are analyzed in the time domain:

[0074] For the G1 link, that is, the PWM regulation link:

[0075] U a (t) = K1w e (t);

[0076] For the G2 link, that is, the mirror drive link:

[0077]

[0078] For the G3 phase, i.e. the mirror rotation phase:

[0079] w a (t) = K3w s (t);

[0080] For the G4 link, i.e. the sampling fiber negative feedback link:

[0081] w c (t) = K4w a (t).

[0082] Based on this, the overall time domain model of the system is:

[0083] JbXj a (t)+(C t C e +K1K3K4C t ) a (t) = K1K3C t w d (t)+K3C t U d (t).

[0084] Perform a simplified calculation on the dynamic structure diagram to obtain the system transfer function:

[0085] The closed-loop transfer function under the reference input w(s) is as follows:

[0086]

[0087] In the interference d The closed-loop transfer function under the action of (s) is as follows:

[0088]

[0089] When the system is simultaneously subjected to target speed input and interference, the total output of the system can be obtained from the superposition principle as follows:

[0090]

[0091] S13, determining a speed feedback signal according to the expected speed and the actual speed, and performing feedback adjustment on the drive signal based on the speed feedback signal. Figure 6 , the Sensor in the figure represents the optical sensor, and the sensor speed measurement target is the spot signal where the optical sensor receives the laser. Figure 6 As an example, assume that the desired speed (i.e., the target speed in the figure) is w d =420rpm, at the initial moment, the PWM maximum value is given to make the motor start quickly, and then the speed output by the sensor speed target point (actual speed) is compared and analyzed with the target speed (expected speed). d >w c , that is, the actual speed is less than the expected speed, then the PWM duty cycle is increased to increase the control voltage Uo; if w d <w c , that is, the actual speed is greater than the expected speed, then the PWM duty cycle is reduced so that the control voltage U o In some embodiments, the following configuration may be performed: before the system is stable, the amplitude of each PWM adjustment is 10%, and after the system is stable, the amplitude of each PWM adjustment is 1%, so as to adjust to a suitable state as quickly as possible.

[0092] For the mirror drive system, a brushed DC motor can be used to drive the motor to rotate through the control voltage output by PWM. The transfer function of the mirror drive system is as follows:

[0093]

[0094] When used within its linear range, it can be approximately regarded as a linear system. Therefore, as the control voltage U o Increase, the output speed w of the mirror drive systems The mirror is increased accordingly, and after passing through a 4:1 reducer, it drives the rotating mirror to It can be understood that the above-mentioned 4:1 reducer is only an example of the rotation ratio of the motor and the rotating mirror provided in the embodiment of the present application, and is not a limitation thereto.

[0095] For the sampling fiber negative feedback link, the optical fiber sampling mirror reflects the light spot signal, and then the eight-bit ADC (analog-to-digital converter with 8-bit resolution) of the optical sensor samples the light spot signal, and finally calculates the current speed signal, that is, the actual speed. Among them, the period of the ADC signal is 203.7us, and a sampling counter can be set. When the ADC does not sample the light spot signal, the counter counts itself, and when the light spot signal is sampled, the rotation period of the mirror can be calculated by the value of the counter and the period value of the ADC, and then the actual speed signal output by the mirror, that is, the speed feedback signal, is obtained. Based on this, the actual speed is feedback-regulated based on the speed feedback signal through the negative feedback link.

[0096] The laser radar speed control method provided in the embodiment of the present application is applied to the above-mentioned laser radar. Not only is the device utilization rate of the laser radar high, the laser emitted by the laser transmitter is only used for speed measurement when the rotating mirror is rotated to a specific angle, and the remaining positions are used for ranging and obstacle avoidance. Moreover, compared with traditional code disks, the optical path of the optical guide path is flexible and not constrained by the structure of the laser radar. It is suitable for most laser radar structures and has a wider range of applications. Since both the detection and transmission and reception sides are based on the laser light source and sensor of the radar main optical path, the detection data is more accurate, and it can also save unit module space and reduce the cost of additional detection devices.

[0097] Through the description of the above implementation methods, ordinary technicians in this field can clearly understand that each implementation method can be implemented by means of software plus a general hardware platform, and of course, it can also be implemented by hardware. Ordinary technicians in this field can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A laser radar, comprising a light emitting component, a light receiving component, a rotating mirror, a motor and a controller, wherein the light receiving component comprises an optical sensor, characterized in that: A light guide path is provided between the optical sensor and the rotating mirror; The light emitting assembly is used to emit laser light to the rotating mirror; The motor is used to drive the rotating mirror to rotate; The rotating mirror is used to reflect the laser to the light guide path when rotating to a preset position, and transmit the laser to the optical sensor through the light guide path; The optical sensor is used to receive the spot signal of the laser; The controller is used to obtain the actual rotation speed and rotation angle of the rotating mirror through the light spot signal.

2. The laser radar according to claim 1, characterized in that: The light receiving assembly also includes a light receiving lens; The rotating mirror is used to reflect the laser to the surrounding environment when rotating to a non-preset position, and is also used to transmit part of the light diffusely reflected by the surrounding environment to the light receiving lens; The light receiving lens is used to receive the light transmitted by the rotating mirror and provide it to the optical sensor.

3. The laser radar according to claim 1, characterized in that: The rotating mirror is a double-sided reflecting mirror, so that when the rotating mirror rotates one circle, the optical sensor receives the light spot signal twice.

4. The laser radar according to claim 1, characterized in that: The light guide path is an optical fiber or a light guide tube.

5. The laser radar according to claim 1, characterized in that: The light path output position of the light guide path corresponds to the corner position of the optical sensor.

6. The laser radar according to claim 1, characterized in that: The laser radar also includes a support frame, and the light emitting component and the light receiving component are fixedly arranged on the support frame, wherein the central axis of the light emitting component and the optical sensor are located in the same vertical plane, and the optical sensor is perpendicular to the central axis of the light emitting component.

7. The laser radar according to claim 1, characterized in that: At least one end of the optical path is provided with a laser collimation component, and the laser collimation component is used to improve the stability of the laser input and / or output of the optical path.

8. A laser radar speed control method, applied to the laser radar according to any one of claims 1 to 7, the method comprising: Determining a driving signal according to a desired rotation speed of the rotating mirror, wherein the driving signal is used to control the motor to drive the rotating mirror to rotate; Acquire a light spot signal, and acquire an actual rotation speed and a rotation angle of the rotating mirror through the light spot signal; A rotation speed feedback signal is determined according to the desired rotation speed and the actual rotation speed, and feedback adjustment is performed on the drive signal based on the rotation speed feedback signal.

9. The method according to claim 8, characterized in that The obtaining of the light spot signal comprises: When the rotating mirror rotates to a preset position, it reflects the laser light to the optical path, and transmits the laser light to the optical sensor through the optical path; The optical sensor receives the optical signal of the laser and converts the optical signal into an electrical signal, which is the light spot signal.

10. The method according to claim 8, characterized in that The obtaining the actual rotation speed and rotation angle of the rotating mirror through the light spot signal comprises: Acquire time information of receiving the light spot signal at least twice; Calculate the actual rotation speed of the rotating mirror according to the time information; The rotation angle of the rotating mirror is calculated according to the actual rotation speed.

11. The method according to claim 8, characterized in that The driving signal is a PWM signal, and the feedback adjustment of the driving signal based on the speed feedback signal includes: The duty cycle of the PWM signal is adjusted based on the speed feedback signal.

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