Angular measurement device for scanning device of laser radar, angular measurement method

Abstract

The application discloses an angle measuring device, method and laser radar of a scanning device. The device comprises a conductor, an angle measuring circuit; wherein the scanning device comprises a scanning mirror, one side of the scanning mirror is a reflecting surface, the other side is a mounting surface, and the scanning mirror can be deflected around at least one axis; the conductor is fixed on the mounting surface; the angle measuring circuit comprises a resonance system and a sampling part, the resonance system comprises an inductive element and a capacitor, the inductive element is fixedly arranged at a preset distance from the static position of the conductor; the sampling part samples and outputs the electric signal of the resonance system, and is used for determining the parameters of the resonance system, so as to determine the deflection angle of the scanning mirror. The purpose of measuring the deflection angle of the scanning mirror is achieved.

Description

Technical Field

[0001] This application relates to the field of laser detection, and in particular to an angle measurement device, an angle measurement method, and a lidar scanning device. Background Technology

[0002] LiDAR (LiDAR) can use scanners to scan at different angles. The LiDAR transmitter uses a scanner whose angle changes over time to deflect the detection beam at different angles, thus achieving scanning detection at various angles. The echo signal reflected by the target object returns to the LiDAR, is received by the photodetector at the receiver, and converted into an electrical signal. After signal processing, information such as the target's distance is obtained, or 3D imaging is achieved. Commonly used scanners may include scanning mirrors.

[0003] In operation, scanning mirror lidar requires measuring the deflection or oscillation angle of the scanning mirror to determine the spatial angular position of each detection beam when it encounters the target. These spatial angular positions are combined with the target distance calculated based on the flight time to determine the three-dimensional spatial position of the target.

[0004] Existing methods for measuring scanning mirror angles include optical lever measurement and piezoelectric / piezoresistive measurement. The principle of optical lever measurement is as follows: Figure 1 As shown, the normal direction of the mirror M at its initial position is horizontal. The scale mark S0 is observed through the telescope T. When the mirror rotates by an angle θ to position M', the mirror normal (the line passing through the geometric center of the mirror and perpendicular to the mirror) rotates by an angle θ, and the scale mark S is observed through the telescope. This is based on the principle of light reflection: The angle θ through which the mirror has rotated can be calculated. The sensitivity and signal-to-noise ratio of the optical lever measurement method are proportional to the length D of the optical lever. Therefore, there is a balance between device size and angle measurement signal-to-noise ratio. It is impossible to improve the signal-to-noise ratio while reducing the device size, which does not conform to the trend of equipment miniaturization.

[0005] Figure 2 This diagram illustrates an angle measurement method based on the piezoelectric / piezoresistive principle. The piezoelectric / piezoresistive measurement method utilizes the deformation structure of the scanning mirror (such as...) Figure 2 Piezoelectric or piezoresistive elements are integrated on the drive beam shown, such as Figure 2 As shown, when the drive beam deflects the scanning mirror, the drive beam itself undergoes deformations such as stretching, compression, or torsion, generating pressure changes on the piezoelectric / piezoresistive elements. This causes changes in the voltage / resistance of the elements, which can be converted into angular changes by measuring the change in voltage / resistance. However, this measurement method can only obtain the angular change and cannot measure the absolute angle of the scanning mirror. When the scanning mirror is deformed or translated (moved along the normal direction of the mirror surface) due to factors such as thermal deformation, this method will produce angular measurement errors. Summary of the Invention

[0006] This application provides an angle measurement device and an angle measurement method for a lidar scanning device.

[0007] In a first aspect, this application provides an angle measuring device for a laser radar scanning apparatus, comprising: the scanning apparatus including a scanning mirror, at least one side of which is a reflective surface and is deflectable about at least one axis to change the direction of the laser radar emitted or reflected beam; a conductor fixed on the scanning mirror; and an angle measuring circuit including a resonant system and a sampling unit, wherein the conductor affects the resonant characteristics of the resonant system, and the sampling unit samples and outputs the electrical signal of the resonant system to determine the parameters of the resonant system in order to determine the deflection angle of the scanning mirror.

[0008] Secondly, embodiments of this application provide a lidar, including a transmitting device for emitting a detection beam; a scanning device including a scanning mirror for deflecting the detection beam toward a target space, the scanning mirror being rotatable about at least one axis; a detection device for receiving the echo beam of the detection beam reflected by the target object and converting it into an electrical signal; and an angle measuring device for the scanning device described in the first aspect for determining the deflection angle of the scanning mirror.

[0009] Thirdly, embodiments of this application provide an angle measurement method, which uses the angle measuring device described in the first aspect to measure the deflection angle of a lidar scanning device. The scanning device includes a scanning mirror, one side of which is a reflective surface and can deflect around at least one axis. The method includes: when the scanning device is in operation, acquiring parameters of the resonant system output by the angle measuring circuit of the scanning device; wherein the angle measuring circuit includes a resonant system; and determining the deflection angle of the scanning mirror based on the parameters.

[0010] The angle measuring device and method for a LiDAR scanning device provided in this application embodiment, by setting a conductor and an angle measuring circuit in the scanning device, including a resonant system, can measure the parameters of the resonant system at resonance, and determine the deflection angle of the scanning mirror through the parameters. The angle measuring device does not require power-supply components on the scanning mirror; therefore, there is no increased demand for power supply and heat dissipation for the scanning mirror, and thus, the angle measuring device does not affect the reliability of the scanning device. Furthermore, the angle measuring device has a simple and compact structure, which can reduce the cost of measuring the deflection angle of the scanning device.

[0011] Based on this, by setting up a reference angle measurement circuit and an edge angle measurement circuit, or by setting up multiple edge angle measurement circuits, the measurement deviation caused by the change in the absolute angle of the scanning mirror due to factors such as thermal deformation and translation can be eliminated, significantly improving the accuracy and reliability of the scanning mirror angle measurement. Attached Figure Description

[0012] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0013] Figure 1 This is a schematic diagram illustrating the angle measurement principle of a LiDAR scanning device in a related technology.

[0014] Figure 2 This is a schematic diagram illustrating the angle measurement principle of a LiDAR scanning device in another related technology.

[0015] Figure 3A Schematic diagrams of the structure of some embodiments of the angle measuring device of the LiDAR scanning device provided in the embodiments of this application;

[0016] Figure 3B for Figure 3A A top view of the scanning mirror and inductor in the embodiment shown;

[0017] Figure 4 for Figure 3A The equivalent circuit diagram of the angle measuring device shown is shown.

[0018] Figure 5 A schematic diagram of the sampling unit for acquiring parameters of a resonant system provided in some embodiments;

[0019] Figure 6 A schematic diagram of the sampling unit for acquiring parameters of a resonant system, provided in some other embodiments;

[0020] Figure 7 For application Figure 3A A schematic diagram illustrating the principle of a scanning mirror deflection angle measuring device for a lidar scanning apparatus according to the embodiment shown.

[0021] Figure 8A Schematic diagrams of the structure of the angle measuring device of the scanning device of the lidar provided in the embodiments of this application;

[0022] Figure 8B for Figure 8A A top view of the scanning mirror and inductor in the illustrated embodiment;

[0023] Figure 9A Schematic diagrams of the structure of the angle measuring device of the scanning device of the lidar provided in the embodiments of this application;

[0024] Figure 9B for Figure 9AA top view of the scanning mirror and inductor in the illustrated embodiment;

[0025] Figure 10 A top view schematic diagram of another scanning mirror and inductor element provided in the embodiments of this application;

[0026] Figure 11 A top view schematic diagram of another scanning mirror and inductor element provided in the embodiments of this application for the scanning device;

[0027] Figure 12 This is a flowchart illustrating the angle measurement method provided in an embodiment of this application. Detailed Implementation

[0028] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] Please combine Figure 3A , Figure 3B , Figure 3A The diagram shows some examples of the angle measurement device of the LiDAR scanning device provided in this application. Figure 3B It shows Figure 3A A top view schematic diagram of the scanning mirror and inductor components.

[0031] The scanning device described above may include a scanning mirror 10. At least one side of the scanning mirror 10 is a reflective surface. The scanning mirror 10 may include one or more axes. The scanning mirror 10 may deflect about at least one axis to change the direction of the laser radar's emitted or reflected beam.

[0032] Figure 3A The image shown is a side view of the scanning mirror.

[0033] The angle measuring device of the aforementioned scanning apparatus includes a conductor 11 and an angle measuring circuit 12. The conductor 11 is fixed to the scanning mirror 10. Optionally, the conductor is fixed on the side of the scanning mirror opposite to the reflecting surface. The conductor 11 can have good conductivity, for example, it is made of a metal material with high conductivity (e.g., aluminum, copper, or their alloys).

[0034] The angle measurement circuit 12 includes a resonant system 120 and a sampling unit 121. The resonant system operates in a resonant state when the scanning mirror rotates. The conductor 11 affects the resonant characteristics of the resonant system. The sampling unit 121 samples and outputs the electrical signal from the resonant system 120 to determine the parameters of the resonant system 120, thereby determining the deflection angle of the scanning mirror 10. These parameters may include equivalent inductance, resonant frequency, resonant period, etc.

[0035] When measuring the deflection angle of the scanning mirror, the angle measuring device of the LiDAR scanning device uses the parameters to determine the deflection distance of the edge of the scanning mirror, and then uses the deflection distance to determine the deflection angle.

[0036] In some applications, the parameter is the resonant frequency or resonant period of the resonant system, and the angle measuring device uses the resonant frequency or resonant period to determine the deflection angle of the scanning mirror.

[0037] In other application scenarios, the parameter is the equivalent inductance of the resonant system, and the angle measuring device uses the equivalent inductance to determine the deflection angle of the scanning mirror.

[0038] This embodiment incorporates a conductor and an angle measurement circuit within the scanning device. The angle measurement circuit includes a resonant system that measures the frequency parameters at resonance. These parameters are used to determine the equivalent inductance of the inductor and the conductor, and the deflection angle of the scanning mirror is then determined based on this equivalent inductance. This angle measurement device eliminates the need for power-supply components on the scanning mirror, thus eliminating the need for power supply and heat dissipation for the scanning mirror. Consequently, the angle measurement device does not affect the reliability of the scanning device. Furthermore, its simple and compact structure reduces the cost of measuring the deflection angle of the scanning device.

[0039] Optionally, as shown in the figure, the resonant system 120 includes an inductor 1201 and a capacitor 1202. The inductor 1201 is fixedly positioned at a preset distance d0 from the conductor 11 at its rest position.

[0040] Typically, the preset distance between the inductor 1201 and the conductor 11 can be greater than the maximum amplitude of the scanning mirror 10. However, if the preset distance is too large, it will reduce the measurement sensitivity. Therefore, the preset distance can be set to be slightly larger than the maximum amplitude of the scanning mirror 10. During operation, the scanning mirror 10 deflects around its axis. The maximum amplitude of the scanning mirror 10 refers to the distance by which the edge of the scanning mirror 10 deviates from its initial position when the deflection amplitude is at its maximum in the normal direction of the initial position of the scanning mirror 10 (that is, the normal direction of the plane where the coil is located).

[0041] The above parameters can be the equivalent inductance of the resonant system 120. The equivalent inductance represents the mutual inductance between the conductor 11 and the inductor 1201, and is related to the distance between the inductor 1201 and the conductor 11.

[0042] The projection of the geometric center of the aforementioned inductor 1201 onto the scanning mirror 10 is offset from the geometric center of the scanning mirror 10. In some applications, the aforementioned angle measurement circuit 12 can be an edge angle measurement circuit. The projection of the inductor 1201 of the aforementioned edge angle measurement circuit 12 onto the scanning mirror 10 is located at the edge of the scanning mirror 10.

[0043] Here, the aforementioned inductor 1201 may include, but is not limited to, a coil. The coil may face the conductor 11, and the plane containing the coil is parallel to the plane containing the conductor 11 in its stationary state.

[0044] Figure 4 It shows Figure 3A The equivalent circuit diagram of the angle measuring device shown is illustrated.

[0045] like Figure 4 As shown, the conductor described above can be equivalent to an inductor-resistor model. The angle measurement circuit 12 also includes an excitation source i. s Incentive source i s This enables the aforementioned resonant system to operate in a resonant state.

[0046] Since the inductor 1201 is oriented towards the conductor, a mutual inductance (L) will be generated between the inductor 1201 and the conductor 11. m The above mutual inductance L m The mutual inductance is modulated by the distance between the inductor and the conductor; that is, the mutual inductance changes as the distance between the inductor and the conductor changes.

[0047] The aforementioned inductor 1201 can be connected in parallel or series with capacitor 1202 to form a resonant circuit. For example... Figure 4 The diagram shows a resonant circuit formed by an inductor and a capacitor connected in parallel, with excitation source i. s This causes the resonant circuit to operate at its resonant point. When the resonant circuit operates at its resonant point, the resonant frequency is:

[0048] (1);

[0049] The above The above is the equivalent inductance, and C is the capacitance value of the capacitor.

[0050] Furthermore, when the scanning mirror 10 deflects around its axis, the conductor 11 mounted on the mounting surface of the scanning mirror 10 deflects with it, and the distance between the conductor 11 and the inductor 1201 changes. Because of this change in distance between the conductor 11 and the inductor 1201, the mutual inductance Lm between them changes, thereby affecting the equivalent inductance of the resonant circuit. The changes occur. By adjusting the excitation signal of the excitation source is, the resonant system is kept in a resonant state. According to formula (1), the frequency of the resonant system is measured, and the equivalent inductance of the resonant system can be obtained. Furthermore, the distance between the conductor and the inductor is determined based on the equivalent inductance at resonance. Then, the deflection angle of the scanning mirror is determined based on this distance.

[0051] The sampling unit 121 can be used to sample the electrical signal of the resonant system 120 and output the sampled signal. The resonant frequency or resonant period of the resonant system 120 can be determined based on the sampled signal output by the sampling unit 121. The equivalent inductance can be determined based on the resonant frequency or resonant period. Then, the actual distance between the conductor 11 and the inductor element 1201 can be determined, and the deflection angle of the scanning mirror 10 can be determined based on the actual distance and the initial distance.

[0052] As an optional implementation, the sampling unit 121 includes an analog-to-digital converter (ADC). The input terminal of the ADC is connected to the resonant system to sample the electrical signal of the resonant system. Figure 5 As shown, the two ends of the parallel inductor and capacitor are connected to the input terminals of the analog-to-digital converter (ADC). The ADC is used to acquire the oscillating sinusoidal wave of the resonant system. The time corresponding to one oscillation, i.e., the oscillation period, is obtained from the sinusoidal analog signal. The resonant frequency is then determined based on the oscillation period.

[0053] As an optional implementation, the sampling unit 121 includes a comparator and a time-to-digital converter, wherein the two signal input terminals of the comparator can be connected to the resonant system, and the output terminal of the comparator is connected to the input terminal of the time-to-digital converter to sample the electrical signal of the resonant system. Figure 6 As shown, the two ends of the parallel inductor and capacitor are connected to the two input terminals of the comparator, respectively. The output terminal of the comparator is connected to a time-to-digital converter. The comparator and time-to-digital converter can convert a sine wave into a square wave, and determine the resonant period or resonant frequency of the resonant system based on the square wave period. The time-to-digital converter has high time resolution, low temperature drift, and high measurement accuracy.

[0054] Furthermore, the angle measuring device of the above-mentioned scanning device also includes a processing unit (not shown in the figure), which is used to determine the resonant frequency of the resonant system based on the output of the above-mentioned sampling unit (when the resonant period is determined, the resonant frequency of the resonant system can be determined based on the relationship between frequency and period).

[0055] After determining the resonant frequency, the equivalent inductance corresponding to the resonant frequency can be calculated according to the above formula (1). Based on the above analysis, the aforementioned equivalent inductance This relates to the distance between the inductor and the conductor. Let d represent the distance between the inductor and the conductor, and the equivalent inductance of the LC resonant system be... =f(d)( It is a function of d.

[0056] As one implementation method, when d is small, ≈L0+k×d, where L0 is the equivalent inductance when d=0, and k is the influence coefficient of d.

[0057] As one implementation method, calibration can be used to determine d and The relationship. Measuring the corresponding values ​​of d. , to obtain d and The distance-inductance relationship, such as d~ A curve or corresponding table is used to store this correspondence in the lidar. In practical applications, the equivalent inductance is determined based on the resonant frequency measured in real time for the resonant system. By finding the corresponding relationship, the value of the distance d between the inductor and the conductor can be obtained.

[0058] Furthermore, the relationship between d and the resonant frequency (or resonant period) of the resonant system can be determined using calibration methods. By measuring the resonant frequency (or resonant period) corresponding to different d values, the corresponding relationship between d and the resonant frequency (or resonant period) can be obtained, such as a relationship curve or a correspondence table. This correspondence can be stored in the lidar. In practical applications, based on the real-time measured resonant frequency (or resonant period) of the resonant system, the frequency-distance correspondence can be looked up to obtain the value of the distance d between the inductive element and the conductor. Please refer to [reference needed]. Figure 7 It shows the application of Figure 3A The illustrated embodiment provides a schematic diagram of the angle measuring device for measuring the deflection angle of a scanning mirror. Since the conductor is fixedly connected to the scanning mirror, in the schematic diagram, the deflection angle of the conductor is equivalent to the deflection angle of the scanning mirror. Figure 7 As shown, the initial state of conductor 11 (stationary state, such as...) Figure 7 The initial distance between the conductor 11 and the inductor 1201 is d0. After the conductor 11 deflects by an angle θ with the scanning mirror, it reaches position 11' (as shown). Figure 7 (As shown by the dashed line), the distance between conductor 11' and inductor 1201 is d1. The deflection distance x of the scanning mirror edge in the normal direction of the plane containing the coil can be calculated. The change in distance x between conductor 11 and inductor 1201, and the deflection angle θ of the scanning mirror, satisfy the tangent trigonometric function relationship. The change in distance x between conductor 11 and inductor 1201 can be regarded as the deflection distance of the scanning mirror edge. The change x = d0 - d1. Assuming the distance from the center of the conductor to the edge of the conductor is h, the deflection angle θ of the scanning mirror satisfies the following tangent trigonometric function relationship with h and x:

[0059] (1);

[0060] Therefore, (2);

[0061] The distance d0 between the projection of the geometric center of the inductor element onto the center of the scanning mirror and the center of the scanning mirror can be determined, as well as the above x. Then, the deflection angle θ of the scanning mirror can be determined according to formula (2).

[0062] One approach is to use a calibration method to determine the correspondence between θ and the aforementioned parameters (resonant frequency or equivalent inductance). For example, the angle-inductance correspondence between θ and the equivalent inductance, or the angle-frequency correspondence between θ and the resonant frequency, can be stored in the lidar. In practical applications, the real-time deflection angle of the scanning mirror can be obtained simply by looking up the corresponding relationships based on the aforementioned parameters of the resonant system.

[0063] In some applications, the above correspondence serves as a calibration curve. In these applications, the angle measurement circuit can determine the deflection angle using the pre-set parameters and the deflection angle calibration curve. That is, in practical applications, it is only necessary to determine the real-time deflection angle of the scanning mirror based on the above parameters of the resonant system and the calibration curve.

[0064] It should be noted that the angle measuring device of the present invention is not limited to... Figure 3A and Figure 7 The conductor shown is fixed to the side of the scanning mirror opposite to the reflecting surface. However, the conductor can be fixed in other locations on the scanning mirror. Alternatively, the conductor can be fixed to the side edge of the scanning mirror.

[0065] The resonant system is not limited to fixing the inductor at a predetermined distance from the conductor in the direction normal to the scanning mirror. As long as the deflection of the scanning mirror can cause the conductor to deflect or move, changing the equivalent inductance of the resonant system, the parameters of the resonant system can be used to characterize the deflection angle of the scanning mirror. As one implementation, the inductor and conductor can be in the same plane at a stationary position. The conductor is fixed on the side of the scanning mirror opposite to the reflecting surface, and the inductor is spaced at a predetermined distance from the conductor in the same plane, i.e., the inductor is positioned around the scanning mirror. As another implementation, the conductor is fixed to the side edge of the scanning mirror, and the inductor is positioned around the scanning mirror at a predetermined distance from the conductor.

[0066] In this embodiment, by providing a conductor and an angle measurement circuit in the scanning device, the angle measurement circuit includes a resonant system. The parameters of the resonant system at resonance can be measured to determine the equivalent inductance of the inductor and the conductor. The deflection angle of the scanning mirror is then determined based on this equivalent inductance. The angle measurement device of the scanning device does not require power-supply components on the scanning mirror. Therefore, there is no need for power supply and heat dissipation for the scanning mirror, and the angle measurement device does not affect the reliability of the scanning device. Furthermore, the angle measurement device has a simple and compact structure, which reduces the cost of measuring the deflection angle of the scanning device.

[0067] Please refer to Figure 8A and Figure 8B This illustrates a structural schematic diagram of the angle measuring device of a scanning apparatus according to other embodiments provided in this application. Figure 8B for Figure 8A A top view of the relative positions of the scanning mirror and inductor components.

[0068] In these embodiments, the angle measuring device of the scanning device includes multiple angle measuring circuits.

[0069] like Figure 8A As shown, the angle measurement circuit includes a reference angle measurement circuit 12' and at least one edge angle measurement circuit 12. Figure 8B As shown, the center of the reference inductor element of the reference angle measurement circuit 12' is substantially overlapped with the geometric center of the scanning mirror in its projection onto the scanning mirror. Each reference angle measurement circuit and edge angle measurement circuit has an inductor element; for example, the reference angle measurement circuit includes a reference inductor element, and the edge angle measurement circuit 12 may include a first inductor element.

[0070] The geometric center of the first inductor element of the edge angle measurement circuit 12 is offset from the geometric center of the scanning mirror 10 in the projection of the scanning mirror 10.

[0071] The scanning mirror 10 has at least one axis, and the geometric center of the first inductive element of the edge angle measuring circuit is located on the axis in which the projection of the scanning mirror 10 lies. Figure 8B As shown, the geometric center of the first inductor element is projected onto the axis R1-R1' in the scanning mirror 10.

[0072] The distance d0 between the reference inductor and the conductor, measured using the reference angle measuring circuit, can be considered as the reference distance between the inductor and the conductor when they are stationary. The first distance d2 between the first inductor and the conductor 11 in the edge angle measuring circuit 12 after the scanning mirror 10 deflects can be measured using the edge angle measuring circuit 12. The deflection angle of the scanning mirror 10 can be determined based on the reference distance d0 and the first distance d2. This embodiment uses an equivalent inductance parameter as an example for illustration.

[0073] Taking an edge angle measurement circuit of 1 as an example, such as Figure 7 As shown, a reference angle measuring circuit 12 is set at the position corresponding to the center of rotation of the scanning mirror. The reference angle measuring circuit consists of a reference inductor, a parallel capacitor, and an excitation circuit. Figure 4 The measurement circuit shown is used to measure the reference distance d0 based on the parameters of the resonant system and the equivalent inductance Le0. An edge angle measurement circuit 12 is set at the position where the deflection amplitude of the scanning mirror 10 is the largest (vibration edge). The edge angle measurement circuit 12 includes a first inductor element, which is also connected to a capacitor and an excitation power supply to form an LC resonant system. It measures the angle change d2 based on the equivalent inductance Le1. The angle change of the scanning mirror is then determined by the difference between the two values, x = d2 - d0.

[0074] In addition, the correspondence between Le1-Le0 and x can be determined. After measuring Le1 and Le0, the difference is calculated, and the corresponding relationship is found based on the difference result Le1-Le0 to obtain the value of x.

[0075] Due to factors such as thermal deformation, the reference distance d0 of the scanning mirror will change. After thermal deformation, the distance d2 between the conductor 11 and the first inductor element corresponding to the same deflection angle of the scanning mirror 10 will change. Figure 8A and Figure 8B In the example shown, the thermal expansion and contraction of the scanning mirror 10 causes d0 and d2 to change synchronously. Therefore, by measuring the distance d0 using the reference inductor and detecting the deflected distance d2 using the first inductor, the angle measurement deviation caused by the change in d0 and d2 due to thermal deformation can be eliminated by the difference x = d2 - d0, thus obtaining the scanning mirror deflection angle more accurately.

[0076] By setting up a reference angle measurement circuit and an edge angle measurement circuit, the deflection distance of the scanning mirror can be measured at different positions. By combining the deflection distances of the scanning mirror measured by the reference angle measurement circuit and the edge angle measurement circuit, the deflection angle of the scanning mirror can be calculated, which can improve the accuracy of angle measurement and eliminate measurement deviations caused by factors such as thermal deformation and translation.

[0077] Please refer to Figure 9A and Figure 9B , Figure 9A This application provides schematic diagrams illustrating the structure of an angle measuring device of a scanning apparatus according to other embodiments. Figure 9B It shows Figure 9A A top view schematic diagram showing the relative positional relationship between the scanning mirror and the inductive element in the scanning device shown.

[0078] In these embodiments, the angle measuring device of the scanning device includes multiple angle measuring circuits. This embodiment uses an equivalent inductance parameter as an example for illustration.

[0079] The angle measurement circuit includes multiple edge angle measurement circuits, wherein the geometric center of the inductive element of the edge angle measurement circuit is offset from the geometric center of the scanning mirror in the projection of the scanning mirror.

[0080] The scanning mirror has at least one axis, and the geometric centers of the inductive elements of at least two edge angle measurement circuits are located at both ends of one of the axes in the projection of the scanning mirror, and are symmetrical about the geometric center of the scanning mirror. Figure 9B As shown, the two edge angle measurement circuits correspond to inductors 1201-1 and 1201-2 respectively. The geometric centers of inductors 1201-1 and 1201-2 are projected onto the axis R2-R2' of the scanning mirror 10.

[0081] For the deflection angle about the first axis, the inductor elements can be set into two groups, corresponding to a second axis perpendicular to the first axis, for example, the second axis... Figure 9B The axis R2-R2' is shown. The geometric centers of the two inductors 1201-1 and 1201-2 are projected onto the scanning mirror at the two ends of the second axis, respectively, to measure the displacements of opposite phase positions on the mirror surface. Figure 9A As shown, the edge angle measurement circuit 12-1 and the edge angle measurement circuit 12-2 are located on the same axis of the scanning mirror at the two ends where the scanning mirror deflection angle is the largest, and are symmetrical about the geometric center of the scanning mirror.

[0082] Edge angle measurement circuit 12-1 may include a first inductor, and edge angle measurement circuit 12-2 may include a second inductor. The equivalent inductance of edge angle measurement circuit 12-1 is Le2, and the equivalent inductance of edge angle measurement circuit 12-2 is Le3. The distance between the first inductor in edge angle measurement circuit 12-1 and conductor 11 is d3. The distance between the second inductor in edge angle measurement circuit 12-2 and conductor 11 is d4.

[0083] As one implementation method, it can be calibrated The correspondence with d4-d3 is determined by measuring the equivalent inductance between the inductor element of the edge angle measuring circuit 12-1 and the conductor 11 according to the method of the embodiment shown in Figure 3. The equivalent inductance between the inductor element and conductor 11 in the edge angle measurement circuit 12-2 Then the difference between the two is calculated. Then, based on the correspondence, determine the corresponding x = d1 - d2.

[0084] By using different sets of edge angle measurement circuits, the deflection distance of the scanning mirror can be measured at different positions. By combining the deflection distances of the scanning mirror measured by the reference angle measurement circuit and the edge angle measurement circuit, the deflection angle of the scanning mirror can be calculated, which can improve the accuracy of angle measurement and eliminate measurement deviations caused by factors such as thermal deformation and translation.

[0085] If there are more than two sets of edge angle measurement circuits, multiple sets of edge angle measurement circuits can be set up to correspond to the second axis mentioned above. The projections of the geometric centers of the inductors of the multiple sets of edge angle measurement circuits onto the scanning mirror are respectively located on the second axis. Multiple deflection distances can be measured using multiple sets of edge angle measurement circuits, and multiple deflection angles can be calibrated. The final scanning mirror deflection angle is determined based on the multiple deflection angles and the position of the inductors. For example, if the projections of the geometric centers of the inductors of two sets of edge angle measurement circuits onto the scanning mirror are located on the same side of the second axis relative to the geometric center of the scanning mirror, the deflection angles measured by the two sets of edge angle measurement circuits can be averaged. If the projections of the geometric centers of the inductors of two sets of edge angle measurement circuits onto the scanning mirror are located at opposite ends of the second axis relative to the geometric center of the scanning mirror, the difference between the deflection angles measured by the two sets of edge angle measurement circuits can be used to calculate the final scanning mirror deflection angle.

[0086] Please refer to Figure 10 This illustrates a schematic diagram showing the relative positional relationship between the inductive element and the scanning mirror in the angle measuring device of a scanning apparatus according to some other embodiments of the present application.

[0087] The angle measuring device may include multiple angle measuring circuits. The projection of the geometric center of the inductor element of the angle measuring circuit onto the scanning mirror 10 is offset from the geometric center of the scanning mirror 10. That is, the multiple angle measuring circuits mentioned above include multiple edge angle measuring circuits. The projections of the inductor elements corresponding to at least two angle measuring circuits onto the scanning mirror 10 are respectively located on different axes of the scanning mirror 10.

[0088] like Figure 10 As shown, the geometric center of the first inductor 1201-3 in an edge angle measurement circuit is projected onto the scanning mirror along the axis R2-R2' of the scanning mirror. The geometric center of the first inductor 1201-4 in an edge angle measurement circuit is projected onto the scanning mirror along the axis R3-R3' of the scanning mirror. Axis axes R2-R2' and R3-R3' are perpendicular to the first axis, respectively.

[0089] According to Figure 3A The angle measuring device of the scanning device provided in the embodiment measures the angle by using the edge angle measuring circuit where the first inductor element 1201-3 is located to measure the deflection angle of the axis R2-R2' of the scanning mirror around the first axis; and using the edge angle measuring circuit where the first inductor element 1201-4 is located to measure the deflection angle of the axis R3-R3' of the scanning mirror around the first axis.

[0090] exist Figure 10 In this method, the deflection angle of the scanning mirror in both axes is measured by setting the edge angle measurement circuit on two axes.

[0091] Please refer to Figure 11 This illustrates a schematic diagram showing the relative positional relationship between the inductive element and the scanning mirror in the angle measuring device of a scanning apparatus according to some other embodiments of the present application.

[0092] In these embodiments, the angle measuring device of the scanning device includes multiple angle measuring circuits.

[0093] The two-dimensional scanning mirror has two mutually perpendicular deflection axes: axis R4-R4' and axis R5-R5'. Axis R4-R4' and axis R5-R5' are perpendicular to a first axis. The geometric centers of the inductive elements of at least two edge angle measurement circuits are projected onto the scanning mirror at both ends of one of the axes and are symmetrical about the geometric center of the scanning mirror.

[0094] like Figure 11 As shown, edge angle measurement circuits can be sequentially set at the edge positions of the scanning mirrors on both axes.

[0095] The deflection angle of the scanning mirror axis R4-R4' around the first axis is measured using the edge angle measuring circuits located at the first inductors 1201-5 and 1201-6, respectively. The deflection angle of the scanning mirror axis R5-R5' along the first axis is measured using the edge angle measuring circuits located at the first inductors 1201-7 and 1201-8, respectively. Reference can be made during the measurement. Figure 9A , Figure 9B The example illustrates a deflection angle measurement scheme. This scheme yields highly accurate deflection angle measurements along both axes of the scanning mirror.

[0096] In some alternative implementations, Figure 8A and Figure 8B , Figure 9A and Figure 9B , Figure 10 , Figure 11 In the angle measurement devices of the LiDAR scanning apparatus in various embodiments, each angle measurement circuit includes a resonant system and an excitation source. By controlling the excitation source of each angle measurement circuit separately, the resonant system of each angle measurement circuit can operate at its own specific resonant frequency. The resonant frequencies of the resonant systems of at least two angle measurement circuits are different. In some application scenarios, the resonant frequencies of the resonant systems corresponding to multiple angle measurement circuits may be different.

[0097] In these alternative implementations, by making the resonant systems of at least two angle measurement circuits different, the mutual interference between the resonant systems can be reduced, thereby improving the accuracy of the measurement results of each angle measurement circuit.

[0098] In some alternative implementations, each angle measurement circuit includes a resonant system and an excitation source. Controlling the excitation source of each angle measurement circuit allows the resonant system to operate at a specific resonant frequency. The timing sequence of the resonant systems in at least two angle measurement circuits is different.

[0099] Specifically, each angle measurement circuit can be configured with its own operating timing sequence. The operating timing sequences of the resonant systems of at least two angle measurement circuits can be different. Within each operating timing sequence, the corresponding angle measurement circuit is in an active state, driven by an excitation circuit to bring its resonant system to a resonant state. After the timing sequence ends, the excitation current of the angle measurement circuit is disconnected. This avoids interference between the resonant systems of the various angle measurement circuits, ensuring the accuracy of the deflection angle measurement.

[0100] In these optional implementations, to improve the efficiency of deflection angle measurement, different resonant frequencies can be set for different angle measurement circuits, allowing multiple resonant systems with minimal interference to simultaneously reach resonance within the same operating sequence. That is, within the same operating sequence, the angle measurement circuits corresponding to at least two resonant systems with minimal mutual interference are simultaneously operational. An excitation circuit is used to bring the resonant systems of these angle measurement circuits to resonance, thereby measuring the deflection angle of the scanning mirror.

[0101] This application also provides a lidar, comprising: a transmitting device for emitting a detection beam; a scanning device including a scanning mirror that deflects the detection beam toward a target space and reflects an echo beam reflected by the target object, the scanning mirror being deflectable about at least one axis; a detection device for receiving the echo beam and converting it into an electrical signal; and as described above. Figures 3A-3B , Figures 8A-8B , Figures 9A-9B , Figure 10 , Figure 11 An angle measuring device of one of the scanning devices is used to determine the deflection angle of the scanning mirror.

[0102] Please refer to Figure 12 It shows a schematic flowchart of an angle measurement method provided in this disclosure, which applies... Figures 3A-3B , Figures 8A-8B , Figures 9A-9B , Figure 10 , Figure 11 An angle measuring device for the scanning device shown in one of the examples.

[0103] like Figure 12 As shown, the above angle measurement method includes:

[0104] Step 101: When the scanning device is in working condition, acquire the parameters of the resonant system output by the angle measurement circuit of the scanning device; wherein, the angle measurement circuit includes the resonant system.

[0105] Step 102: Determine the deflection angle of the scanning mirror based on the parameters.

[0106] In this embodiment, the scanning device may include a scanning mirror. At least one side of the scanning mirror is a reflective surface. The angle measuring device of the scanning device may include a conductor and an angle measuring circuit. The angle measuring circuit includes a resonant system. The conductor is mounted on the mounting surface of the scanning mirror, and the conductor affects the resonant characteristics of the resonant system.

[0107] When the scanning device is in operation, the scanning mirror deflects. The conductor mounted on the scanning mirror also deflects with the scanning mirror. The parameters of the resonant system change with the deflection of the scanning mirror and the conductor.

[0108] The deflection angle of the scanning mirror can be determined based on the parameters of the resonant system.

[0109] Specifically, the resonant system may include an inductor and a capacitor. The inductor is fixed at a predetermined distance from the stationary position of the conductor.

[0110] An inductor and a conductor generate mutual inductance, and the inductor and mutual inductance determine the equivalent inductance. The mutual inductance is related to the distance between the inductor and the conductor. Thus, the equivalent inductance is modulated by the distance between the inductor and the conductor.

[0111] Prior to step 101 above, the angle measurement method of the scanning device further includes: using an excitation source to make the resonant system work in a resonant state.

[0112] The aforementioned resonant system can operate in a resonant state under the action of an excitation signal. When the resonant system resonates, the resonant frequency, capacitance, and equivalent inductance satisfy the relationship of the above formula (1). Therefore, the equivalent inductance can be determined by measuring the resonant frequency.

[0113] In some alternative implementations, step 102 above includes the following steps:

[0114] The current distance between the inductor and the conductor is determined according to a predetermined distance-parameter correspondence; wherein the distance-parameter correspondence reflects the correspondence between the distance between the inductor and the conductor and the parameters of the resonant system; the deflection angle of the scanning mirror is determined according to the distance.

[0115] A calibration curve relating the deflection angle of the scanning mirror to the parameters of the resonant system can be determined beforehand through calibration. After the angle measurement circuit outputs the parameters of the resonant system, the deflection angle of the scanning mirror can be determined based on the aforementioned calibration curve.

[0116] In this embodiment, the angle measurement circuit further includes a sampling unit, and step 101 further includes: the sampling unit samples and outputs the electrical signal output by the resonant system to determine the parameters. These parameters include the equivalent inductance of the resonant system, the resonant frequency, or the resonant period. The resonant frequency can be determined by the resonant period.

[0117] Furthermore, the aforementioned angle measurement circuit also includes a processing unit. The processing unit receives the output of the sampling unit and determines the period of change of the electrical signal as the resonant period of the resonant system.

[0118] In some optional implementations, the angle measurement circuit includes a reference angle measurement circuit and at least one edge angle measurement circuit; each reference angle measurement circuit and the edge angle measurement circuit has an inductor element, the geometric center of the reference inductor element of the reference angle measurement circuit substantially overlaps with the geometric center of the scanning mirror in its projection on the scanning mirror; the geometric center of the first inductor element of the edge angle measurement circuit is offset from the geometric center of the scanning mirror in its projection on the scanning mirror; and step 102 above includes the following sub-steps:

[0119] Sub-step 1021: Determine the reference distance between the reference inductor element and the geometric center of the scanning mirror based on the reference equivalent inductance output by the reference angle measurement circuit.

[0120] Sub-step 1022: Determine the first distance between the first inductor element and the geometric center of the scanning mirror based on the measurement equivalent inductance output by the edge angle measurement circuit.

[0121] Further, step 102 above includes: determining the deflection angle of the scanning mirror based on the reference distance and the first distance.

[0122] In some application scenarios, the above-mentioned angle measurement circuit includes: the geometric center of the first inductor of at least one edge angle measurement circuit is located on the axis of the scanning mirror when its projection is on the axis of the scanning mirror, and the deflection angle of the scanning mirror on the axis is determined according to the reference distance and the first distance.

[0123] In some alternative implementations, the angle measurement circuit includes multiple edge angle measurement circuits, the geometric center of the first inductor element of the edge angle measurement circuit being offset from the geometric center of the scanning mirror in the projection of the scanning mirror, and step 102 further includes:

[0124] Multiple edge angle measurement circuits are used to measure the first distance between their respective inductive elements and conductors, and the deflection angle of the scanning mirror is determined by the multiple first distances.

[0125] In some alternative implementations, the geometric centers of the inductive elements of at least two edge angle measurement circuits are symmetrical about the geometric center of the scanning mirror in the projection of the inductor.

[0126] The method of using multiple edge angle measurement circuits to measure the first distance between their respective inductive elements and conductors, and determining the deflection angle of the scanning mirror through multiple first distances includes:

[0127] The deflection angle of the scanning mirror is determined based on the respective first distances between the inductor elements and conductors of the at least two edge angle measuring circuits.

[0128] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An angle measuring device for a lidar scanning apparatus, comprising: Conductor, multi-angle measurement circuit; in The scanning device includes a scanning mirror, at least one side of which is a reflective surface and can be deflected about at least one axis to change the direction of the laser radar emitted or reflected beam. The conductor is fixed to the scanning mirror; Each of the plurality of angle measurement circuits includes a resonant system and a sampling unit. The conductor affects the resonant characteristics of the resonant system. The sampling unit samples and outputs the electrical signal of the resonant system to determine the parameters of the resonant system, thereby determining the deflection angle of the scanning mirror. Wherein, the parameter is the equivalent inductance of the resonant system, and the angle measuring device uses the equivalent inductance to determine the deflection angle of the scanning mirror; the resonant system includes an LC resonant system, the LC resonant system includes an inductor and a capacitor, and the inductor is fixedly set at a preset distance from the stationary position of the conductor; The plurality of angle measurement circuits include a reference angle measurement circuit and at least one edge angle measurement circuit; the resonant systems of the reference angle measurement circuit and the edge angle measurement circuit each have an inductive element; the operating timing of the resonant systems of the reference angle measurement circuit and the at least one edge angle measurement circuit is different; The geometric center of the inductor element of the reference angle measuring circuit is substantially overlapped with the geometric center of the scanning mirror in the projection of the scanning mirror. The geometric center of the inductive element of the edge angle measurement circuit is offset from the geometric center of the scanning mirror in the projection of the scanning mirror.

2. The angle measuring device of the laser radar scanning device according to claim 1, wherein, The angle measuring device of the laser radar uses the parameters to determine the deflection distance of the scanning mirror edge, and then uses the deflection distance to determine the deflection angle.

3. The angle measuring device of the laser radar scanning device according to claim 1, wherein, The scanning mirror has at least one axis, and the geometric center of the inductive element of the edge angle measurement circuit is located on the axis in the projection of the scanning mirror.

4. The angle measuring device of the laser radar scanning device according to claim 1, wherein, The angle measurement circuit includes multiple edge angle measurement circuits, and the geometric center of the inductive element of the edge angle measurement circuit is offset from the geometric center of the scanning mirror in the projection of the scanning mirror.

5. The angle measuring device of the laser radar scanning device according to claim 4, wherein, The scanning mirror has at least one axis, and the geometric centers of the inductive elements of at least two edge angle measurement circuits are located at both ends of one of the axes in the projection of the scanning mirror, and are symmetrical about the geometric center of the scanning mirror.

6. The angle measuring device of the laser radar scanning device according to claim 1, wherein, The angle measurement circuit determines the deflection angle using the preset parameters and the calibration curve of the deflection angle.

7. The angle measuring device of a scanning device of a lidar according to claim 1, wherein, The angle measuring device of the scanning device further includes a processing unit, which is used to determine the parameters of the resonant system based on the output of the sampling unit.

8. The angle measuring device of the laser radar scanning apparatus according to claim 7, wherein the processing unit determines the change period of the electrical signal as the resonance period of the resonant system.

9. A lidar, comprising: A transmitting device used to emit a probe beam; A scanning device, including a scanning mirror, deflects the detection beam into the target space and reflects the echo beam reflected by the target object. The scanning mirror can be deflected about at least one axis. The detection device receives the echo beam and converts it into an electrical signal; and An angle measuring device of a scanning device of a lidar as claimed in one of claims 1 to 8 for determining a deflection angle of the scanning mirror.

10. A method of measuring an angle of deflection of a scanning device of a laser radar using an angle measuring device as claimed in any one of claims 1-8, wherein The scanning device comprises a scanning mirror on which a conductor is fixed, the angle measuring circuit comprises a resonant system, the method comprises: acquiring parameters of the resonant system; determining a deflection angle of the scanning mirror from the parameters.

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