Angle measuring device and method for scanning device in laser radar

Abstract

The device, method and laser radar for measuring the angle of a scanning device include a conductor (11) and an angle measuring circuit (12), the scanning device includes a scanning mirror (10), the scanning mirror (10) has a reflecting surface on one side and a mounting surface on the other side, and is deflectable around at least one axis, the conductor (11) is fixed to the mounting surface, the angle measuring circuit (12) includes a resonant system (120) and a sampling unit (121), the resonant system (120) includes an inductance element (1201) and a capacitance (1202), the inductance element (1201) is fixedly installed at a predetermined distance from the rest position of the conductor (11), and the sampling unit (121) samples and outputs the electrical signal of the resonant system (120) to determine the parameters of the resonant system (120), thereby determining the deflection angle of the scanning mirror (10). The purpose of measuring the deflection angle of the scanning mirror is achieved.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to a Chinese patent application bearing application number 202110442203.6 filed on April 23, 2021 and entitled "Angle measurement device and angle measurement method for scanning device in laser radar," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the field of laser detection, and in particular to an angle measuring device for a scanning device in a laser radar, an angle measuring method, and a laser radar. [Background technology]

[0003] Laser radar can achieve scanning at different angles using a scanner. The emitting end of the laser radar deflects the emitted detection beam at different angles by a scanner whose angle changes over time, thereby achieving scanning and detection at different angles. The echo signal of the detection beam reflected by the target returns to the laser radar, is received by the photodetector at the receiving end and converted into an electrical signal, and is processed to obtain information such as the distance to the target, or to achieve three-dimensional imaging. A typical scanner may include a scanning mirror.

[0004] During operation, a scanning mirror laser radar must determine the spatial angular position of each detection beam when it encounters a target by measuring the deflection or wobble angle of the scanning mirror, and these spatial angular positions, in combination with the target range calculated based on the time of flight, determine the three-dimensional spatial position of the target.

[0005] Conventional methods for measuring the angle of a scanning mirror include the optical lever measurement method and the piezoelectric / piezoresistive measurement method. The principle of the optical lever measurement is as shown in Figure 1. The normal direction of the initial position of the mirror surface M is set to be horizontal, and the scale graduation S0 is seen from the telescope T. When the mirror surface rotates by an angle of θ, it reaches the position M', and the mirror surface normal (a line passing through the geometric center of the mirror surface and perpendicular to the mirror surface) rotates by an angle of θ, and the scale graduation S is seen from the telescope. The angle θ by which the mirror surface rotates can be calculated from the principle of light reflection, tan2θ=(S-S_0) / D. The sensitivity and signal-to-noise ratio of the optical lever measurement method are proportional to the length D of the optical lever, so there is a balanced relationship between the device size and the signal-to-noise ratio of the angle measurement. It is not possible to increase the signal-to-noise ratio while reducing the volume of the device, which does not fit the trend of equipment miniaturization.

[0006] Figure 2 shows a schematic diagram of an angle measurement method based on the piezoelectric / piezoresistive principle. In the piezoelectric / piezoresistive measurement method, a piezoelectric element or a piezoresistive element is integrated in the strain structure of the scanning mirror (the driving beam shown in Figure 2). As shown in Figure 2, when the driving beam drives and deflects the scanning mirror, the driving beam itself is strained by tension, compression, twist, etc., and a pressure change occurs in the piezoelectric / piezoresistive element, which changes the voltage / resistance of the element. By measuring the amount of change in voltage / resistance, it can be converted into an angle change. However, this measurement method can only obtain the amount of angle change and cannot measure the absolute angle of the scanning mirror. In the case of deformation of the scanning mirror due to factors such as thermal deformation or translational motion (movement of the mirror surface along the normal direction), angle measurement errors may occur. Summary of the Invention

[0007] The present application provides an angle measuring device and an angle measuring method for a scanning device in a laser radar, and a laser radar.

[0008] In a first aspect, the present application provides an angle measurement device for a scanning device in a laser radar, comprising a conductor and an angle measurement circuit, wherein the scanning device comprises a scanning mirror, at least one side of which is a reflective surface and which is deflectable around at least one axis to change the direction of an emitted beam or a reflected beam of the laser radar, the conductor is fixed to the scanning mirror, the angle measurement circuit comprises a resonance system and a sampling unit, the conductor affects the resonance characteristics of the resonance system, and the sampling unit samples and outputs an electrical signal of the resonance system to determine parameters of the resonance system, thereby determining the deflection angle of the scanning mirror.

[0009] In a second aspect, an embodiment of the present application provides a laser radar including an emission device for emitting a detection beam, a scanning device including a scanning mirror deflectable about at least one axis, for deflecting the detection beam into a target space and for reflecting an echo beam reflected by the detection beam from a target, a detection device for receiving the echo beam and converting it into an electrical signal, and an angle measurement device of the scanning device according to the first aspect for determining the deflection angle of the scanning mirror.

[0010] In a third aspect, an embodiment of the present application provides an angle measuring method for measuring a deflection angle of a laser radar scanning device using the angle measuring device described in the first aspect, wherein the scanning device includes a scanning mirror, a conductor is fixed to the scanning mirror, and the angle measuring circuit includes a resonant system, the angle measuring method comprising the steps of: acquiring parameters of the resonant system; and determining a deflection angle of the scanning mirror based on the parameters.

[0011] The angle measuring device and angle measuring method of the scanning device in the laser radar provided by the embodiment of the present application can measure parameters at the time of resonance in the resonance system by installing a conductor in the scanning device and an angle measuring circuit including a resonant system, and determine the deflection angle of the scanning mirror by the parameters. The angle measuring device of the scanning device does not require components that require power supply to be installed on the scanning mirror, so there is no requirement for power supply or heat dissipation for the scanning mirror, and therefore the angle measuring device does not affect the reliability of the scanning device. In addition, the angle measuring device has a simple and compact structure, and can reduce the cost of measuring the deflection angle of the scanning device.

[0012] Furthermore, by installing a reference angle measurement circuit and an edge angle measurement circuit, or by installing multiple edge angle measurement circuits, it is possible to eliminate measurement variations due to changes in the absolute angle of the scanning mirror caused by factors such as thermal deformation and translational motion, and to significantly improve the angle measurement accuracy and reliability of the scanning mirror. [Brief description of the drawings]

[0013] Other characteristics, objects and advantages of the present application will become more apparent upon reading the detailed description given below of non-limiting examples with reference to the drawings in which: [Figure 1] FIG. 1 is a schematic diagram of the angle measurement principle of a scanning device in a laser radar in one related art. [Diagram 2] FIG. 13 is a schematic diagram of the angle measurement principle of a scanning device in a laser radar according to another related technology. [Figure 3A] 1A to 1C are configuration diagrams of several embodiments of an angle measuring device of a scanning device in a laser radar provided by an embodiment of the present application. [Figure 3B] FIG. 3B is a plan view of the scanning mirror and the inductance element in the embodiment shown in FIG. 3A. [Figure 4] 3B is an equivalent circuit schematic diagram of the angle measuring device shown in FIG. 3A. [Diagram 5] FIG. 1 is a block diagram of a sampling unit provided by some embodiments for collecting parameters of a resonant system. [Figure 6] FIG. 11 is a configuration diagram for collecting parameters of a resonant system using a sampling unit provided in some other embodiments. [Figure 7] 3B is a schematic diagram showing the principle of measuring the deflection angle of a scanning mirror, which is applied to the angle measuring device of the scanning device in the laser radar according to the embodiment shown in FIG. 3A. [Figure 8A] 10A to 10C are configuration diagrams of several other embodiments of an angle measuring device of a scanning device in a laser radar provided by an embodiment of the present application. [Figure 8B] FIG. 8B is a plan view of the scanning mirror and the inductance element in the embodiment shown in FIG. 8A. [Figure 9A] 10A to 10C are configuration diagrams of several other embodiments of an angle measuring device of a scanning device in a laser radar provided by an embodiment of the present application. [Figure 9B] FIG. 9B is a plan view of the scanning mirror and the inductance element in the embodiment shown in FIG. 9A. [Figure 10] 11 is a plan view of another scanning mirror and inductance element of a scanning device provided by an embodiment of the present application. FIG. [Figure 11] 1 is a plan view of another scanning mirror and inductance element of a scanning device provided by an embodiment of the present application. [Figure 12] 1 is a flowchart of an angle measurement method provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present application will be described in more detail below with reference to the drawings and examples. It can be understood that the specific examples described in this specification are merely for the purpose of interpreting the relevant invention, and do not limit the invention. It should be further explained that, for the convenience of explanation, only the parts related to the invention are shown in the drawings.

[0015] It should be noted that the embodiments and features in the embodiments of the present application may be combined with each other as long as they are not mutually exclusive. The present application will now be described in detail based on the embodiments with reference to the accompanying drawings.

[0016] Please refer to FIG. 3A which shows a configuration diagram of some examples of angle measuring devices of a scanning device in a laser radar provided by the present application, and FIG. 3B which shows a plan view of the scanning mirror and inductance element in FIG. 3A.

[0017] The scanning device may include a scanning mirror 10. The scanning mirror 10 has at least one reflective surface on one side. The scanning mirror 10 may include one or more axes. The scanning mirror 10 may be deflected about at least one axis to change the direction of the laser radar's emitted beam or reflected beam.

[0018] FIG. 3A shows a side view of the scanning mirror.

[0019] The angle measuring device of the scanning device includes a conductor 11 and an angle measuring circuit 12. The conductor 11 is fixed to the scanning mirror 10. Optionally, the conductor 11 is fixed to the surface of the scanning mirror 10 opposite to the reflecting surface. The conductor 11 may have good electrical conductivity, such as being made of a metal material with high electrical conductivity (e.g., aluminum, copper, or an alloy thereof).

[0020] 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 resonance characteristics of the resonant system. The sampling unit 121 samples and outputs an electrical signal of the resonant system 120 to determine parameters of the resonant system 120, thereby determining the deflection angle of the scanning mirror 10. The parameters may include an equivalent inductance, a resonant frequency, a resonant period, etc.

[0021] When measuring the deflection angle of the scanning mirror 10, the angle measuring device of the scanning device in 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.

[0022] In some application scenarios, the parameter is a resonant frequency or a resonant period of the resonant system, and the angle measuring device uses the resonant frequency or the resonant period to determine the deflection angle of the scanning mirror.

[0023] In some other application scenarios, the parameter is an equivalent inductance of the resonant system, and the angle measurement device uses the equivalent inductance to determine the deflection angle of a scanning mirror.

[0024] In this embodiment, a conductor is installed in the scanning device, and an angle measuring circuit including a resonant system is installed, so that the parameters at the time of resonance in the resonant system are measured, and the equivalent inductance of the inductance element and the conductor is determined by the parameters, and then the deflection angle of the scanning mirror can be determined based on the equivalent inductance. The angle measuring device of the scanning device does not require any components that require power supply to be installed on the scanning mirror, so there is no requirement for power supply or heat dissipation for the scanning mirror, and therefore the angle measuring device does not affect the reliability of the scanning device. In addition, the angle measuring device has a simple and compact structure, and can reduce the cost of measuring the deflection angle of the scanning device.

[0025] 3A, the resonant system 120 includes an inductance element 1201 and a capacitance 1202. The inductance element 1201 is fixedly installed at a preset distance d0 from the rest position of the conductor 11.

[0026] In general, the preset distance between the inductance element 1201 and the conductor 11 may be larger than the maximum amplitude of the scan mirror 10. However, if the preset distance is too large, the measurement sensitivity decreases, so the preset distance may be set to a value slightly larger than the maximum amplitude of the scan mirror 10. The scan mirror 10 deflects around its axis during operation, and the maximum amplitude of the scan mirror 10 refers to the distance that the edge of the scan mirror 10 is displaced from its initial position when the deflection width of the scan mirror 10 is maximum in the normal direction of the initial position of the scan mirror 10 (i.e., the normal direction of the plane on which the coil is located).

[0027] Said parameter may be the equivalent inductance of the resonant system 120 , which represents the mutual inductance between the conductor 11 and the inductance element 1201 and is related to the distance between the inductance element 1201 and said conductor 11 .

[0028] The projection of the geometric center of the inductance element 1201 on the scanning mirror 10 is offset from the geometric center of the scanning mirror 10. In some application scenarios, the angle measurement circuit 12 may be an edge angle measurement circuit. The projection of the inductance element 1201 of the edge angle measurement circuit 12 on the scanning mirror 10 is at the edge of the scanning mirror 10.

[0029] Here, the inductance element 1201 may include, but is not limited to, a coil. The coil may face the conductor 11, and the plane in which the coil is located is parallel to the plane in which the conductor 11 is located in a stationary state.

[0030] FIG. 4 shows a schematic diagram of an equivalent circuit of the angle measuring device shown in FIG. 3A.

[0031] As shown in FIG. 4, the conductor may be equivalent to an inductance-resistance model. The angle measurement circuit 12 includes an excitation source (i.e., an excitation circuit in the figure) i s Further includes an excitation source i s causes the resonant system to operate in a resonant state.

[0032] Since the inductance element 1201 faces the conductor, a mutual inductance (L m ) occurs. The above mutual inductance L m is modulated by the distance between the inductance element and the conductor, i.e., the mutual inductance (L m ) changes with the change in the distance between the inductance element 1201 and the conductor 11.

[0033] The inductance element 1201 can be connected in parallel or in series with the capacitance 1202 to form a resonant circuit. FIG. 4 shows a resonant circuit consisting of an inductance element and a capacitance connected in parallel, and an excitation source i s causes the resonant circuit to operate at the resonance point. When the resonant circuit operates at the resonance point, the resonant frequency is given by the following equation (1). JPEG0007669520000001.jpg1330(1)

[0034] the above JPEG0007669520000002.jpg77 is the equivalent inductance above, and C above is the capacitance value of the capacitance.

[0035] Furthermore, when the scan mirror 10 is deflected around the axis, the conductor 11 attached to the mounting surface of the scan mirror 10 is deflected following the scan mirror, and the distance between the conductor 11 and the inductance element 1201 changes. Since the distance between the conductor 11 and the inductance element 1201 changes, the mutual inductance L between the conductor 11 and the inductance element 1201 changes. m changes, and the equivalent inductance of the resonant circuit JPEG0007669520000003.jpg77 changes. Excitation source i s By adjusting the excitation signal, the resonant system is always operated in a resonant state, the frequency of the resonant system is measured according to equation (1), and the equivalent inductance of the resonant system is calculated. JPEG0007669520000004.jpg77 is obtained, and the distance between the conductor and the inductance element can be determined based on the equivalent inductance at resonance. Furthermore, the deflection angle of the scanning mirror 10 is determined based on the distance between the conductor 11 and the inductance element 1201.

[0036] The sampling unit 121 can sample the electrical signal of the resonance system 120 and output the sampling signal. The resonance frequency or resonance period of the resonance system 120 can be determined based on the sampling signal output from the sampling unit 121, and the equivalent inductance can be determined based on the resonance frequency or resonance period, and then the actual distance between the conductor 11 and the inductance element 1201 can be determined based on the equivalent inductance, and the deflection angle of the scanning mirror 10 can be determined based on the actual distance and the initial distance.

[0037] As an alternative implementation, the sampling unit 121 includes an analog-digital converter. An input end of the analog-digital converter is connected to the resonant system to achieve sampling of the electrical signal of the resonant system. As shown in FIG. 5, both ends of an inductance element and a capacitance connected in parallel are respectively connected to input ends of the analog-digital converter. The analog-digital converter is used to collect the oscillating sine wave of the resonant system, and the time corresponding to one oscillation, i.e., the oscillation period, is obtained based on the sine wave analog signal. The resonant frequency is determined based on the oscillation period.

[0038] As an alternative implementation, the sampling unit 121 includes a comparator and a time-to-digital converter (TDC), two signal input terminals of the comparator may be connected to the resonant system, and an output terminal of the comparator is connected to an input terminal of the time-to-digital converter to achieve sampling of the electrical signal of the resonant system. As shown in FIG. 6, both ends of the parallel-connected inductance element and capacitance are respectively connected to two input terminals of the comparator. The output terminal of the comparator is connected to the time-to-digital converter. The comparator and the time-to-digital converter (TDC) can convert a sine wave into a square wave, and determine the resonant period or resonant frequency of the resonant system according to the square wave period. The time-to-digital converter (TDC) has high time resolution, small temperature drift, and high measurement accuracy.

[0039] Furthermore, the angle measuring device of the scanning device further includes a processing unit (not shown), which is for determining the resonant frequency of the resonant system based on the output of the sampling unit (when the resonant period is determined, the resonant frequency of the resonant system can be determined based on the relationship between the frequency and the period).

[0040] After the resonant frequency is determined, the equivalent inductance corresponding to the resonant frequency is calculated according to the above formula (1). According to the above analysis, the equivalent inductance JPEG0007669520000006.jpg77 is related to the distance between the inductance element and the above conductor. The distance between the inductance element and the conductor is represented as d, and the equivalent inductance of the LC resonant system is JPEG0007669520000007.jpg77=f(d)( JPEG0007669520000008.jpg77 is a function of d).

[0041] In one embodiment, when d is small, JPEG0007669520000009.jpg711L0+kxd, where L0 is the equivalent inductance when d=0, and k is the influence coefficient of d.

[0042] In one embodiment, d and The relationship between JPEG0007669520000010.jpg77 can be determined by a calibration method. Measure JPEG0007669520000011.jpg77 and find d and JPEG0007669520000012.jpg77 distance-inductance correspondence, e.g., d~ JPEG0007669520000013.jpg77 curve or correspondence table is obtained, and the correspondence is stored in the laser radar. In practical application, the equivalent inductance is calculated based on the resonance frequency of the resonance system measured in real time. By determining JPEG0007669520000014.jpg77 and searching for the corresponding relationship, the value of the distance d between the inductance element and the conductor can be obtained.

[0043] Also, the relationship between d and the resonant frequency (or resonant period) of the resonant system can be determined by a calibration method. The resonant frequency (or resonant period) corresponding to different d values ​​is measured to obtain a correspondence relationship between d and the resonant frequency (or resonant period), for example, a relation curve or a correspondence table, and the correspondence relationship is stored in the laser radar. In practical applications, the frequency-distance correspondence relationship can be searched based on the resonant frequency (or resonant period) measured in real time for the resonant system, thereby obtaining the value of the distance d between the inductance element 1201 and the conductor 11. Please refer to FIG. 7 showing a principle schematic diagram of measuring the deflection angle of the scanning mirror applied to the angle measuring device according to the embodiment shown in FIG. 3A. Since the conductor 11 and the scanning mirror 10 are fixedly connected, in the principle schematic diagram, the deflection angle of the conductor 11 is equivalent to the deflection angle of the scanning mirror 10. As shown in FIG. 7, the initial distance between the initial state of the conductor 11 (the stationary state shown by the solid line in FIG. 7) and the inductance element 1201 is set to d0. After the conductor 11 follows the scan mirror and is deflected by an angle θ, it reaches position 11' (shown by the dashed line in FIG. 7), and the distance between the conductor 11' and the inductance element 1201 becomes d1. The deflection distance x of the edge of the scan mirror 10 in the normal direction of the plane on which the coil is located can be calculated. The deflection angle θ of the scan mirror 10 and the change amount x of the distance between the conductor 11 and the inductance element 1201 satisfy a tangent trigonometric function relationship. The change amount x of the distance between the conductor 11 and the inductance element 1201 can be regarded as the deflection distance of the edge of the scan mirror 10. The change amount x=d0-d1. If the distance from the center of the conductor to the edge of the conductor is h, the deflection angle θ of the scan mirror, h, and x satisfy the following tangent trigonometric function relationship: JPEG0007669520000015.jpg1234(2), Therefore, JPEG0007669520000016.jpg1233(3).

[0044] By determining the distance d0 between the projection of the geometric center of the inductance element on the scanning mirror and the center of the scanning mirror, and the above x, the deflection angle θ of the scanning mirror can then be determined according to equation (3).

[0045] In one embodiment, the corresponding relationship between θ and the above parameters (resonant frequency or equivalent inductance), such as the angle-inductance corresponding relationship between θ and equivalent inductance, or the angle-frequency corresponding relationship between θ and resonant frequency, can be determined by a calibration method and stored in the laser radar. In practical application, the real-time deflection angle of the scanning mirror can be obtained by simply searching the corresponding relationship based on the above parameters of the resonant system.

[0046] In some application scenarios, the above-mentioned correspondence is a calibration curve. In these application scenarios, the angle measurement circuit can determine the deflection angle using the preset calibration curve of the above-mentioned parameters and the deflection angle. That is, in practical application, it is only necessary to determine the real-time deflection angle of the scanning mirror based on the above-mentioned parameters of the resonant system and the calibration curve.

[0047] It should be noted that the angle measuring device of the present invention is not limited to the aspect in which the conductor 11 is fixed to the surface opposite to the reflecting surface of the scanning mirror 10 as shown in Figures 3A and 7, and the conductor 11 may be fixed to other positions on the scanning mirror 10. In one embodiment, the conductor 11 may be fixed to a side edge of the scanning mirror 10.

[0048] The resonant system is not limited to a fixed type in which the inductance element is spaced a predetermined distance from the conductor 11 in the normal direction of the scan mirror 10, but may be such that the deflection of the scan mirror 10 drives the conductor 11 to deflect or move, changing the equivalent inductance of the resonant system, and the resonant system parameters can be used to characterize the deflection angle of the scan mirror. In one embodiment, the inductance element 1201 may be located in the same plane as the rest position of the conductor 11. The conductor 11 is fixed to the surface of the scan mirror opposite to the reflecting surface, and the inductance element 1201 is spaced a predetermined distance from the conductor 11 in the plane in which the conductor 11 is located, i.e., the inductance element 1201 is located around the scan mirror 10. In another implementation, the conductor 11 is fixed to a side edge of the scan mirror 10, and the inductance element 1201 is spaced a predetermined distance from the conductor 11 and located around the scan mirror 10.

[0049] In this embodiment, the conductor 11 is installed in the scanning device, and an angle measuring circuit including a resonant system is installed, so that the parameters at the time of resonance in the resonant system are measured, and the equivalent inductance of the inductance element and the conductor is determined by the parameters, and then the deflection angle of the scanning mirror can be determined based on the equivalent inductance. The angle measuring device of the scanning device does not require any components that require power supply to be installed on the scanning mirror, so there is no requirement for power supply or heat dissipation for the scanning mirror, and therefore the angle measuring device does not affect the reliability of the scanning device. In addition, the angle measuring device has a simple and compact structure, and can reduce the cost of measuring the deflection angle of the scanning device.

[0050] Please refer to FIG. 8A which shows a configuration diagram of an angle measuring device of a scanning device according to some other embodiments provided by the present application, and FIG. 8B which is a plan view of the relative positions of the scanning mirror and the inductance element in FIG. 8A.

[0051] In these embodiments, the scanning device angle measurement device includes a plurality of angle measurement circuits.

[0052] As shown in Fig. 8A, the angle measurement circuit includes a reference angle measurement circuit 12' and at least one edge angle measurement circuit 12. As shown in Fig. 8B, the projection of the center of the reference inductance element of the reference angle measurement circuit 12' on the scanning mirror substantially overlaps with the geometric center of the scanning mirror. Each of the reference angle measurement circuit 12' and the edge angle measurement circuit 12 may have one inductance element, for example, the reference angle measurement circuit 12' may include a reference inductance element and the edge angle measurement circuit 12 may include a first inductance element.

[0053] The projection of the geometric center of the first inductance element of the edge angle measurement circuit 12 onto the scanning mirror 10 is offset from the geometric center of the scanning mirror.

[0054] The scan mirror 10 has at least one axis, and the projection of the geometric center of the first inductance element of the edge angle measurement circuit 12 on the scan mirror 10 is located on the axis. As shown in FIG. 8B, the projection of the geometric center of the first inductance element on the scan mirror 10 is located on the axis R1-R1'.

[0055] The distance d0 between the reference inductance element and the conductor 11 measured by the reference angle measurement circuit 12' can be regarded as a reference distance between the inductance element and the conductor 11 at rest. The edge angle measurement circuit 12 can be used to measure a first distance d2 between a first inductance element in the edge angle measurement circuit 12 and the conductor 11 after the scanning mirror 10 is deflected. The deflection angle of the scanning mirror 10 can be determined from the reference distance d0 and the first distance d2. In this embodiment, an example will be described in which the parameter is equivalent inductance.

[0056] Taking the number of edge angle measuring circuits 12 as an example, the reference angle measuring circuit 12 is installed at a position corresponding to the rotation center of the scanning mirror as shown in Fig. 7. The reference inductance element in the reference angle measuring circuit is connected in parallel with the capacitance and the excitation circuit to form the measurement circuit shown in Fig. 4, and the parameters of the resonant system, the equivalent inductance L e0The edge angle measurement circuit 12 is installed at a position (vibration edge) where the deflection width of the scanning mirror 10 is maximum. The edge angle measurement circuit 12 includes a first inductance element, which is similarly connected to a capacitance and an excitation power source to form an LC resonance system, and has an equivalent inductance L e1 Then, the difference between the two, x=d2-d0, is used to determine the angle change of the scanning mirror.

[0057] Also, L e1 -L e0 Calibrate the correspondence between and x, and L e1 and L e0 Measure and calculate the difference, and the result of the difference is L e1 -L e0 You can also find the x value by searching for the correspondence from

[0058] Since the reference distance d0 of the scan mirror changes due to factors such as thermal strain, the distance d2 between the conductor 11 and the first inductance element corresponding to the same angle of deflection of the scan mirror 10 after thermal deformation changes. In the example shown in Figures 8A and 8B, d0 and d2 change synchronously due to thermal expansion and cold contraction of the scan mirror 10. Therefore, based on the difference between x = d2 - d0, the angle measurement deviation due to the changes in d0 and d2 caused by thermal deformation can be eliminated from the distance d0 measured by the reference inductance element and the distance d2 after deflection detected by the first inductance element, and the deflection angle of the scan mirror can be obtained more accurately.

[0059] Since a reference angle measurement circuit and an edge angle measurement circuit are installed, the deflection distance of the scanning mirror can be measured at different positions, and the deflection angle of the scanning mirror can be calculated by combining the deflection distances of the scanning mirror measured by the reference angle measurement circuit and the edge angle measurement circuit, thereby improving the accuracy of the angle measurement and eliminating measurement variations due to factors such as thermal deformation and translational motion.

[0060] Please refer to FIG. 9A which shows a schematic diagram of an angle measuring device of a scanning device of some other embodiments provided by the present application, and FIG. 9B which shows a plan view of the relative positional relationship between the scanning mirror and the inductance element in the scanning device shown in FIG. 9A.

[0061] In these embodiments, the angle measuring device of the scanning device includes a plurality of angle measuring circuits. In this embodiment, the parameter is taken as an example to be the equivalent inductance.

[0062] The angle measurement circuit includes a plurality of edge angle measurement circuits, and the projections of the geometric centers of the inductance elements of the edge angle measurement circuits on the scanning mirror are offset from the geometric center of the scanning mirror.

[0063] The scanning mirror has at least one axis, and the projections of the geometric centers of the inductance elements of at least two edge angle measurement circuits on the scanning mirror are located at both ends of one of the axes and are symmetrical with respect to the geometric center of the scanning mirror. As shown in Fig. 9B, the two edge angle measurement circuits correspond to the inductance elements 1201-1 and 1201-2, respectively, and the projections of the geometric centers of the inductance elements 1201-1 and 1201-2 on the scanning mirror 10 are located on the axis R2-R2'.

[0064] The inductance elements can be two sets with respect to the deflection angle around the first axis, each corresponding to a second axis perpendicular to the first axis, for example, the axis R2-R2' shown in FIG. 9B. The projections of the geometric centers of the two inductance elements 1201-1 and 1201-2 on the scanning mirror are located at both ends of the second axis, respectively, and measure the displacement of the positions on the mirror surface with opposite motion phases. As shown in FIG. 9A, the edge angle measurement circuit 12-1 and the edge angle measurement circuit 12-2 are located at both ends of the scanning mirror on the same axis where the deflection angle of the scanning mirror is maximum, and are symmetrical with respect to the geometric center of the scanning mirror.

[0065] The edge angle measurement circuit 12-1 may include a first inductance element, and the edge angle measurement circuit 12-2 may include a second inductance element. The equivalent inductance of the edge angle measurement circuit 12-1 is Le2, and the equivalent inductance of the edge angle measurement circuit 12-2 is Le3. The distance between the first inductance element and the conductor 11 in the edge angle measurement circuit 12-1 is d3. The distance between the second inductance element and the conductor 11 in the edge angle measurement circuit 12-2 is d4.

[0066] In one embodiment, The correspondence between JPEG0007669520000017.jpg715 and d4-d3 is calibrated, and the equivalent inductance between the inductance element of the edge angle measurement circuit 12-1 and the conductor 11 is calculated by the method of the embodiment shown in FIG. JPEG0007669520000018.jpg77, and the equivalent inductance between the inductance element of the edge angle measurement circuit 12-2 and the conductor 11 JPEG0007669520000019.jpg77 was measured, and the difference between the two was JPEG0007669520000020.jpg715 is obtained, and then the corresponding x=d1-d2 can be determined based on the correspondence relationship.

[0067] By using different sets of edge angle measurement circuits, the deflection distance of the scanning mirror can be measured at different positions, and the deflection distance of the scanning mirror measured by the reference angle measurement circuit and the edge angle measurement circuit can be combined to calculate the deflection angle of the scanning mirror, thereby improving the accuracy of the angle measurement and eliminating measurement variations due to factors such as thermal deformation and translational movement.

[0068] When there are more than two sets of edge angle measuring circuits, the multiple sets of edge angle measuring circuits can be installed to correspond to the second axis, the projections of the geometric centers of the inductance elements of the multiple sets of edge angle measuring circuits on the scanning mirror are located on the second axis, the multiple sets of edge angle measuring circuits measure multiple deflection distances, calibrate multiple deflection angles, and determine the final deflection angle of the scanning mirror by combining the multiple deflection angles and the positions of the inductance elements. For example, the projections of the geometric centers of the inductance elements of two of the edge angle measuring circuits on the scanning mirror are located on the same side of the geometric center of the scanning mirror on the second axis, and the average value of the deflection angles measured by the two sets of edge angle measuring circuits can be obtained. When the projections of the geometric centers of the inductance elements of the two of the edge angle measuring circuits on the scanning mirror are located on both ends of the geometric center of the scanning mirror on the second axis, the difference between the deflection angles measured by the two sets of edge angle measuring circuits can be obtained and used to calculate the final deflection angle of the scanning mirror.

[0069] Please refer to FIG. 10 which shows a schematic diagram of the relative positional relationship between an inductance element and a scanning mirror in an angle measuring device of a scanning device according to some other embodiments provided by the present application.

[0070] The angle measuring device may include a plurality of angle measuring circuits. The projections of the geometric centers corresponding to the inductance elements of the angle measuring circuits on the scanning mirror 10 are shifted from the geometric center of the scanning mirror 10. That is, the plurality of angle measuring circuits include a plurality of edge angle measuring circuits. The projections of the inductance elements corresponding to at least two angle measuring circuits on the scanning mirror 10 are located on different axes of the scanning mirror 10.

[0071] 10, the projection of the geometric center of the first inductance element 1201-3 of one edge angle measurement circuit on the scanning mirror is located on the axis R2-R2' of the scanning mirror. The projection of the geometric center of the first inductance element 1201-4 of one edge angle measurement circuit on the scanning mirror is located on the axis R3-R3' of the scanning mirror. The axes R2-R2' and R3-R3' are each perpendicular to the first axis.

[0072] The angle measuring means of the angle measuring device of the scanning device provided by the embodiment shown in Figure 3A can measure the deflection angle of the axis R2-R2' of the scanning mirror about the first axis using the edge angle measuring circuit in which the first inductance element 1201-3 is located, and can measure the deflection angle of the axis R3-R3' of the scanning mirror about the first axis using the edge angle measuring circuit in which the first inductance element 1201-4 is located.

[0073] In FIG. 10, the edge angle measurement circuits are provided on the two axial lines to realize the measurement of the deflection angles in the two axial directions of the scanning mirror.

[0074] Please refer to FIG. 11 which shows a schematic diagram of the relative positional relationship between an inductance element and a scanning mirror in an angle measuring device of a scanning device according to some other embodiments provided by the present application.

[0075] In these embodiments, the angle measurement device of the scanning device includes a plurality of angle measurement circuits.

[0076] The two-dimensional scanning mirror has two deflection axes, namely, an axis R4-R4' and an axis R5-R5', which are perpendicular to each other. The axis R4-R4' and the axis R5-R5' are each perpendicular to a first axis. Projections of the geometric centers of the inductance elements of at least two edge angle measurement circuits on the scanning mirror are located at both ends of one of the axes and are symmetrical with respect to the geometric center of the scanning mirror.

[0077] As shown in FIG. 11, edge angle measurement circuits may be provided in sequence at the edge positions of the scanning mirror on the two axes.

[0078] The deflection angle of the scanning mirror axis R4-R4' around the first axis is measured using the edge angle measurement circuits in which the first inductance elements 1201-5 and 1201-6 are located, respectively. The deflection angle of the scanning mirror axis R5-R5' along the first axis is measured using the edge angle measurement circuits in which the first inductance elements 1207 and 1208 are located, respectively. For the measurement, the deflection angle measurement means described in the examples shown in Figures 9A and 9B can be referred to. Highly accurate deflection angle measurement results can be obtained on the two axial directions of the scanning mirror.

[0079] In some alternative implementations, in the angle measuring device of the laser radar scanning device according to the embodiments of Fig. 8A and Fig. 8B, Fig. 9A and Fig. 9B, Fig. 10, and Fig. 11, each angle measuring circuit includes a resonant system and an excitation source. By controlling the excitation source of each angle measuring circuit, the resonant system of each angle measuring circuit can be operated at a specific resonant frequency. The resonant frequencies of the resonant systems of at least two angle measuring circuits are different. In some application scenarios, the resonant frequencies of the resonant systems corresponding to the multiple angle measuring circuits may be different.

[0080] In these selectable implementation forms, by making the resonant frequencies of the resonant systems of at least two angle measurement circuits different, it is possible to reduce mutual interference between the resonant systems and to increase the accuracy of the measurement results by each angle measurement circuit.

[0081] In some other embodiments, each angle measurement circuit includes a resonant system and an excitation source, and the excitation source of each angle measurement circuit is controlled to operate the resonant system at a specific resonant frequency. The operation timings of the resonant systems of at least two angle measurement circuits are different.

[0082] Specifically, each operation timing can be set for each angle measurement circuit. Here, the operation timings of the resonance systems of at least two angle measurement circuits may be different. Within each operation timing, the angle measurement circuit corresponding to that operation timing is put into an operating state, and the resonance system corresponding to that operation timing is put into a resonant state by being driven by an excitation circuit. After that timing ends, the excitation current of that angle measurement circuit is cut off. This makes it possible to avoid interference between the resonance systems of each angle measurement circuit and ensure the accuracy of the measurement of the deflection angle.

[0083] In these selectable realization modes, in order to improve the efficiency of measuring the deflection angle, different resonant frequencies can be set for different angle measurement circuits, and multiple resonant systems with little interference can be simultaneously brought into a resonant state within the same operation timing. That is, within the same operation timing, angle measurement circuits corresponding to at least two resonant systems with little mutual interference are simultaneously brought into an operating state, and the resonant systems of these angle measurement circuits are brought into a resonant state by an excitation circuit to measure the deflection angle of the scanning mirror.

[0084] The present application further provides a laser radar including an emission device for emitting a detection beam, a scanning device including a scanning mirror deflectable around at least one axis, deflecting the detection beam into a target space and reflecting an echo beam reflected by the target from the detection beam, a detection device for receiving the echo beam and converting it into an electrical signal, and an angle measurement device of the scanning device as shown in one of Figures 3A-3B, 8A-8B, 9A-9B, 10 and 11 for determining the deflection angle of the scanning mirror.

[0085] Please refer to FIG. 12, which shows a schematic flow diagram of one of the angle measurement methods provided by the present disclosure, which is applied to the angle measurement device of the scanning device shown in one of FIGS. 3A-3B, 8A-8B, 9A-9B, 10 and 11.

[0086] As shown in FIG. 12, the angle measurement method includes steps 101 and 102.

[0087] In step 101, the parameters of the resonant system are obtained.

[0088] When the scanning device is in an operating state, parameters of a resonant system output by an angle measurement circuit of the scanning device can be obtained, where the angle measurement circuit includes the resonant system.

[0089] In step 102, a deflection angle of the scanning mirror is determined based on the parameters.

[0090] 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 attached to a mounting surface of the scanning mirror, and the conductor affects the resonant characteristics of the resonant system.

[0091] When the scanning device is in operation, the scanning mirror deflects, the conductor attached to the scanning mirror deflects accordingly, and the parameters of the resonant system change with the deflection of the scanning mirror and the conductor.

[0092] The deflection angle of the scanning mirror can be determined based on the parameters of the resonant system.

[0093] Specifically, the resonant system may include an inductance element and a capacitance, the inductance element being fixedly installed at a preset distance from the rest position of the conductor.

[0094] Mutual inductance occurs between the inductance element and the conductor, and the equivalent inductance is determined by the inductance element and the mutual inductance. The mutual inductance is related to the distance between the inductance element and the conductor. Thus, the equivalent inductance is modulated by the distance between the inductance element and the conductor.

[0095] The angle measuring method for the scanning device further includes, before step 101, a step of operating the resonant system in a resonant state using an excitation source.

[0096] The above resonant system can operate in a resonant state under the action of an excitation signal. When the resonant system is resonating, the resonant frequency, the capacitance, and the equivalent inductance satisfy the relationship of the above formula (1). Therefore, the above equivalent inductance can be determined from the measured resonant frequency.

[0097] In some alternative implementations, step 102 includes: The method includes a step of determining a current distance between the inductance element and the conductor based on a previously determined distance-parameter correspondence relationship, the distance-parameter correspondence relationship indicating a correspondence relationship between the distance between the inductance element and the conductor and a parameter of a resonant system, and a step of determining a deflection angle of a scanning mirror based on the distance.

[0098] A calibration curve between the deflection angle of the scanning mirror and the parameters of the resonant system can be determined in advance through a calibration method, and after the angle measurement circuit outputs the parameters of the resonant system, the deflection angle of the scanning mirror can be determined according to the calibration curve.

[0099] In this embodiment, the angle measuring circuit further includes a sampling unit, and the above step 101 further includes a step in which the sampling unit samples and outputs the electrical signal output by the resonant system to determine the parameters. The parameters include the equivalent inductance, resonant frequency, or resonant period of the resonant system. The resonant frequency can be determined from the resonant period.

[0100] The angle measuring circuit further includes a processing unit that receives the output of the sampling unit and determines the change period of the electrical signal as the resonance period of the resonance system.

[0101] In some selectable implementations, the angle measurement circuit includes a reference angle measurement circuit and at least one edge angle measurement circuit, the reference angle measurement circuit and the edge angle measurement circuit each have one inductance element, a projection of a geometric center of a reference inductance element of the reference angle measurement circuit onto the scanning mirror substantially overlaps with the geometric center of the scanning mirror, and a projection of a geometric center of a first inductance element of the edge angle measurement circuit onto the scanning mirror is offset from the geometric center of the scanning mirror, and the above step 102 includes the following sub-steps 1021 and 1022.

[0102] In sub-step 1021, a reference distance between the reference inductance element and the geometric center of the scanning mirror is determined based on the reference equivalent inductance output by the reference angle measurement circuit.

[0103] In sub-step 1022, a first distance between the first inductance element and a geometric center of the scanning mirror is determined based on the measured equivalent inductance output by the edge angle measurement circuit.

[0104] Furthermore, step 102 includes determining a deflection angle of the scanning mirror based on the reference distance and the first distance.

[0105] In some application scenarios, the angle measurement circuit includes a projection of a geometric center of a first inductance element of at least one edge angle measurement circuit on the scanning mirror, the projection being located on an axis of the scanning mirror, and determining a deflection angle of the scanning mirror on the axis based on the reference distance and the first distance.

[0106] In some alternative implementations, the angle measurement circuit includes a plurality of edge angle measurement circuits, and a projection of a geometric center of a first inductance element of the edge angle measurement circuit on the scanning mirror is offset from a geometric center of the scanning mirror, and step 102 further includes: The method further includes measuring a first distance between each inductance element and a conductor using a plurality of edge angle measurement circuits, respectively, and determining a deflection angle of the scanning mirror from the plurality of first distances.

[0107] In some alternative implementations, projections of geometric centers of inductance elements of at least two edge angle measurement circuits on the scanning mirror are symmetrical with respect to the geometric center of the scanning mirror; and the step of measuring a first distance between each inductance element and a conductor using a plurality of edge angle measurement circuits, and determining a deflection angle of the scanning mirror from the plurality of first distances, The method includes determining a deflection angle of the scanning mirror based on a first distance between each of the inductance elements and a conductor of the at least two edge angle measurement circuits.

[0108] The above is merely a description of the preferred embodiment and the technical principles applied in this application. It is obvious to those skilled in the art that the scope of the invention of this application is not limited to the technical means based on the specific combination of the above technical features, but should also include other technical means formed by any combination of the above technical features or equivalent features without departing from the above inventive concept. For example, it also includes technical means formed by replacing the above features with technical features having similar functions according to the disclosure of this application (not limited thereto).

Claims

1. An angle measuring device for a scanning device in a laser radar, comprising: a conductor; and an angle measuring circuit, the scanning device includes a scanning mirror, at least one side of which is a reflective surface, and which is deflectable about at least one axis to redirect an emitted beam or a reflected beam of the laser radar; the conductor is fixed to the scanning mirror; the angle measuring circuit includes a resonance system and a sampling unit, The conductor affects the resonance characteristics of the resonance system, the sampling unit samples and outputs the electrical signal of the resonant system to determine a parameter of the resonant system, thereby determining a deflection angle of the scanning mirror; An angle measuring device for a scanning device in a laser radar, wherein the parameter is an equivalent inductance of the resonant system, the angle measuring circuit and the conductor are arranged to produce a linear relationship between the equivalent inductance and the deflection distance of the scanning mirror, and the deflection angle is determined based on the deflection distance.

2. 2. The angle measuring device for a scanning device in a laser radar according to claim 1, wherein the resonant system includes an inductance element and a capacitance, and the inductance element is fixedly installed at a preset distance from a stationary position of the conductor.

3. 3. The angle measuring device for a scanning device in a laser radar according to claim 2, wherein a projection of a geometric center of the inductance element on the scanning mirror is offset from a geometric center of the scanning mirror.

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

5. 2. The angle measuring device of a scanner in a laser radar according to claim 1, wherein the angle measuring device of the scanner includes a plurality of angle measuring circuits.

6. the plurality of angle measuring circuits include a reference angle measuring circuit and at least one edge angle measuring circuit, each of the reference angle measuring circuit and the edge angle measuring circuit having an inductance element; a projection of a geometric center of an inductance element of the reference angle measurement circuit on the scanning mirror substantially overlaps with a geometric center of the scanning mirror; 6. The angle measuring device for a scanner in a laser radar according to claim 5, wherein a projection of a geometric center of an inductance element of the edge angle measuring circuit on the scanning mirror is offset from a geometric center of the scanning mirror.

7. 7. The angle measuring device for a scanning device in a laser radar according to claim 6, wherein the scanning mirror has at least one axis, and a projection of a geometric center of an inductance element of the edge angle measuring circuit on the scanning mirror is located on the axis.

8. 6. The angle measuring device for a scanning device in a laser radar according to claim 5, wherein the angle measuring circuit includes a plurality of edge angle measuring circuits, and projections of the geometric centers of the inductance elements of the edge angle measuring circuits on the scanning mirror are offset from the geometric center of the scanning mirror.

9. 9. An angle measuring device for a scanning device in a laser radar as described in claim 8, wherein the scanning mirror has at least one axis, and projections of the geometric centers of the inductance elements of at least two edge angle measuring circuits on the scanning mirror are located at both ends of one of the axes and are symmetrical with respect to the geometric center of the scanning mirror.

10. 2. The angle measuring device for a scanning device in a laser radar according to claim 1, wherein said angle measuring circuit determines the deflection angle by using a calibration curve of said preset parameters and said deflection angle.

11. 2. The angle measuring device for a scanner in a laser radar according to claim 1, further comprising a processing unit for determining parameters of the resonant system based on an output of the sampling unit.

12. 12. The angle measuring device for a scanner in a laser radar according to claim 11, wherein the processing unit determines a change period of the electrical signal as a resonance period of the resonance system.

13. 10. An angle measuring device for a scanner in a laser radar according to claim 5, wherein at least two angle measuring circuits have different resonant frequencies and / or different operation timings.

14. an emission device for emitting a detection beam; a scanning device including a scanning mirror deflectable about at least one axis for deflecting the detection beam into a target space and for reflecting an echo beam reflected by the target from the detection beam; a detector that receives the echo beam and converts it into an electrical signal; and an angle measuring device for a scanning device in a laser radar according to any one of claims 1 to 13 for determining the deflection angle of the scanning mirror.

15. A method for measuring a deflection angle of a scanning device in a laser radar using the angle measuring device according to any one of claims 1 to 13, the scanning device including a scanning mirror, a conductor fixed to the scanning mirror, and the angle measuring circuit including a resonant system, obtaining parameters of the resonant system; determining a deflection angle of the scanning mirror based on the parameters.

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