On-orbit automatic calibration method and device for scanning laser radar MEMS swing mirror control parameters

Abstract

The application provides a scanning laser radar MEMS swing mirror control parameter on-orbit automatic calibration method and device, the method comprises the following steps: establishing a reference point of swing mirror control parameters according to the swing mirror application range and the maximum swing mirror deflection angle range; selecting a single-point measurement residence time according to the update period of the nominal deflection angle data of the MEMS swing mirror; configuring the measurement parameters of the laser radar during calibration, including the measurement distance threshold value of the laser, the frequency of the laser, the bias angle of the laser and the scaling coefficient of the laser; after receiving the ground instruction or according to the pre-set calibration time, the swing mirror reaches the corresponding angle position and stays for the single-point measurement residence time according to the reference point set in step S1, so that the swing mirror is in a stable state, and the corresponding angle A / D value is recorded; a fitting model is established, the data is fitted according to the angle A / D value, and the model parameter value is obtained; the obtained model parameter value is loaded into the processor for real-time processing application of the processor.

Description

TECHNICAL FIELD

[0001] The application relates to a scanning laser radar MEMS swing mirror control parameter on-orbit automatic calibration method and device, which is suitable for real-time on-orbit automatic calibration of MEMS swing mirror control parameters, so that the control parameters can be autonomously calibrated and changed according to the on-orbit environmental conditions, external environmental changes are avoided to affect product mechanical and electrical parameters, the parameters pre-calibrated on the ground are prevented from drifting, and the measurement accuracy of the product is affected. BACKGROUND

[0002] With the progress of space technology and the diversified development of space tasks, the demand for the measurement of the attitude of a space non-cooperative target is more and more urgent. The application of laser to obtain the point cloud of a space non-cooperative target has the characteristics of long action distance, high ranging accuracy, small influence of external light environment, and all-day working capability, and is a commonly used measurement system for the pose measurement of a space non-cooperative target.

[0003] In the development process of a laser radar product, a MEMS swing mirror control parameter calibration technology is involved. The technology directly determines whether the laser beam can accurately point to a target in the closed-loop tracking and aiming process of the target. The pointing direction of the laser is controlled by the deflection angle of the MEMS swing mirror, and the deflection angle is controlled by a 10-bit D / A converter. The maximum control code value of the MEMS swing mirror is [0, 4095]. In order to measure the deflection angle of the MEMS swing mirror, an A / D converter is arranged to measure the actual deflection angle of the MEMS swing mirror, and the value range of the A / D is [0, 16383]. In the tracking and aiming process of the target, a basic process is that in the target capturing process, the A / D value of the effective data of the MEMS swing mirror is read and the average value is obtained to obtain the angle value of the position of the target. Then, the D / A value is set to control the MEMS swing mirror to rotate a specific angle to point to the target, so as to realize the tracking and aiming process of the target once.

[0004] Therefore, for the tracking and aiming process of the above laser radar, it is necessary to determine the parameters between the A / D value of the angle measurement of the MEMS swing mirror and the D / A value of the angle control. A commonly used method is to perform an external calibration test on the ground to determine and load the parameters for long-term use. However, for a scanning laser radar, the calibration parameters are very critical, and with the changes of the external environment such as temperature, air pressure and vibration impact, the parameters may drift to a certain extent, which affects the tracking and aiming performance of the laser radar. SUMMARY

[0005] In order to realize real-time on-orbit automatic calibration of the MEMS swing mirror control parameters of the laser radar, and overcome the parameter drift problem of the ground calibration parameters caused by external environment changes, the application provides an on-orbit automatic calibration method for the MEMS swing mirror control parameters of a scanning laser radar.

[0006] The technical scheme provided by the application is as follows:

[0007] In a first aspect, an on-orbit automatic calibration method for the MEMS swing mirror control parameters of a scanning laser radar comprises the following steps:

[0008] S1, establishing reference points of the swing mirror control parameters according to the swing mirror application range and the maximum swing mirror deflection angle range, the number of reference points in the azimuth angle direction and the elevation angle direction is not less than 5;

[0009] S2, selecting a single-point measurement residence time according to the update period of the nominal deflection angle data of the MEMS swing mirror;

[0010] S3, configuring the measurement parameters of the laser radar during calibration, including the measurement distance threshold value of the laser, the frequency of the laser, the bias angle of the laser, and the scaling coefficient of the laser;

[0011] S4, after receiving the ground instruction or according to the pre-set calibration time, controlling the swing mirror to reach the corresponding angle position and stay for the single-point measurement residence time according to the reference points set in step S1, so that the swing mirror is in a stable state, and the corresponding angle A / D value is recorded;

[0012] S5, establishing a fitting model, fitting the data according to the angle A / D value obtained in step S4 to obtain the model parameter value;

[0013] S6, loading the model parameter value obtained in step S5 into the processor for real-time processing application by the processor.

[0014] In a second aspect, an on-orbit automatic calibration system for the MEMS swing mirror control parameters of a scanning laser radar comprises:

[0015] A reference point selection module is configured to establish reference points of the swing mirror control parameters according to the swing mirror application range and the maximum swing mirror deflection angle range, and the number of reference points in the azimuth angle direction and the elevation angle direction is not less than 5;

[0016] A single-point measurement residence time determination module is configured to select a single-point measurement residence time according to the update period of the nominal deflection angle data of the MEMS swing mirror;

[0017] a laser radar measurement parameter determination module configured to determine measurement parameters of the laser radar during calibration, including a measurement distance threshold value of the laser, a frequency of the laser, a bias angle of the laser, and a scaling coefficient of the laser;

[0018] a ground instruction receiving module configured to receive a ground instruction and drive the fitting model setting module

[0019] an A / D value determination module configured to control the mirror to reach a corresponding angle position and stay at a single point for measuring the dwell time according to a set reference point, make the mirror in a stable state, and record a corresponding angle A / D value;

[0020] a fitting model setting module configured to fit data and obtain a model parameter value according to the obtained angle A / D value;

[0021] a loading module configured to load the obtained model parameter value into a processor for real-time processing and application by the processor.

[0022] In a third aspect, a scanning laser radar MEMS mirror control parameter on-orbit automatic calibration device is provided, comprising:

[0023] one or more processors;

[0024] a storage device configured to store one or more programs,

[0025] when the one or more programs are executed by the one or more processors, the one or more processors implement the scanning laser radar MEMS mirror control parameter on-orbit automatic calibration method of the first aspect.

[0026] In a fourth aspect, a readable storage medium is provided, and the readable storage medium stores a computer program, which is executed by a processor to implement the scanning laser radar MEMS mirror control parameter on-orbit automatic calibration method of the first aspect.

[0027] According to the scanning laser radar MEMS mirror control parameter on-orbit automatic calibration method and device provided by the present application, the following beneficial effects are achieved:

[0028] (1) The scanning laser radar MEMS mirror control parameter on-orbit automatic calibration method and device provided by the present application realize the on-orbit automatic calibration of the MEMS mirror control parameter, can correct the MEMS mirror control parameter in time according to the change of external environmental factors, and ensure the pointing accuracy of the laser beam.

[0029] (2) The application provides a scanning laser radar MEMS swing mirror control parameter on-orbit automatic calibration method and device. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A flowchart of the scanning laser radar MEMS swing mirror control parameter on-orbit automatic calibration method of the application;

[0031] Figure 2 The data fitting curve in the azimuth direction in Example 1;

[0032] Figure 3 The data fitting curve in the elevation direction in Example 1;

[0033] Figure 4 The results before and after correction of the MEMS swing mirror DA-AD curve in Example 1;

[0034] Figure 5 The tracking and pointing measurement effect diagram of the laser radar on a static target before and after correction of the MEMS swing mirror DA-AD curve in Example 1. DETAILED DESCRIPTION

[0035] The characteristics and advantages of the application will become more apparent with the following detailed description of the application.

[0036] The special word "exemplary" here means "serving as an example, embodiment or illustration". Any embodiment described as "exemplary" here is not necessarily to be construed as superior or better than other embodiments. The drawings are not necessarily drawn to scale, unless otherwise specified.

[0037] According to a first aspect of the application, a scanning laser radar MEMS swing mirror control parameter on-orbit automatic calibration method is provided, as shown in Figure 1 The method comprises the following steps:

[0038] S1, establishing a reference point of the swing mirror control parameter, the number of reference points in each angle direction is not less than 5, and the distribution of the reference points fully considers the swing mirror application range and the maximum swing mirror deflection angle range.

[0039] In the step S1, the number of reference points in each angle direction is not less than 5, the number of reference points is symmetrically distributed at the center point position of the swing mirror control variable, and the center commonly used field of view weight is not less than the edge field of view weight on the distribution interval.

[0040] S2, according to the update period of the nominal deflection angle data of the MEMS swing mirror, a single-point measurement residence time is selected.

[0041] In this step S2, the single-point measurement residence time is greater than the update period of the nominal deflection angle data of the MEMS swing mirror, and is usually 2-5 update periods of the nominal deflection angle data of the MEMS swing mirror.

[0042] S3, the measurement parameters of the laser radar during calibration are configured, including the measurement distance threshold value of the laser, the frequency of the laser, the bias angle of the laser, and the scaling coefficient of the laser.

[0043] In this step S3, the lower limit of the measurement distance threshold value of the laser is set to zero, and the upper limit is set to the maximum ranging value, so as to ensure that all scanning points in a frame of laser scanning are recognized as valid scanning points by the product. The scaling coefficient of the laser should be set to a large value to ensure that all scanning points in a frame of laser are concentrated in the bias angle range, so that the scanned laser becomes a laser beam with very small divergence angle.

[0044] S4, after receiving the ground instruction or according to the pre-set calibration time, the reference point set in step S1 is controlled to control the swing mirror to reach the corresponding angle position and stay for a single-point measurement residence time, so that the swing mirror is in a stable state, and the corresponding angle A / D value is recorded.

[0045] S5, a fitting model is established, and the angle A / D value obtained in step S4 is used to fit the data to obtain the model parameter value.

[0046] In this step S5, a fitting model is established according to the input and output characteristics of the MEMS swing mirror control quantity, and the fitting model is preferably a linear fitting model or a polynomial fitting model, and the data fitting method is preferably the least square method.

[0047] S6, the model parameter value obtained in step S5 is loaded into the processor in orbit for real-time processing application by the processor.

[0048] In this step S6, the step of loading the parameter value obtained in step S5 into the processor in orbit includes modifying the fitting model of the MEMS swing mirror by injecting instructions, and modifying the specific value of the fitting model parameter.

[0049] According to the second aspect of the present application, a scanning laser radar MEMS swing mirror control parameter on-orbit automatic calibration device is provided, comprising:

[0050] The reference point selection module is used to establish the reference point of the swing mirror control parameter, and the number of reference points in each angle direction is not less than 5, and the distribution of the reference points fully considers the swing mirror application range and the maximum swing mirror deflection angle range.

[0051] The single-point measurement residence time determination module is configured to determine the single-point measurement residence time according to an update period of the nominal deflection angle data of the MEMS swing mirror.

[0052] The laser radar measurement parameter determination module is configured to configure measurement parameters of the laser radar during calibration, including a measurement distance threshold value of the laser, a frequency of the laser, a bias angle of the laser, and a scaling coefficient of the laser.

[0053] The ground instruction receiving module is configured to receive a ground instruction to drive the fitting model setting module

[0054] The A / D value determination module is configured to control the swing mirror to reach a corresponding angle position and stay for a single-point measurement residence time according to a set reference point, so that the swing mirror is in a stable state, and a corresponding angle A / D value is recorded.

[0055] The fitting model setting module is configured to fit data according to the obtained angle A / D value to obtain a model parameter value.

[0056] The loading module is configured to load the obtained model parameter value into the processor for real-time processing and application by the processor.

[0057] According to a third aspect of the present application, a scanning laser radar MEMS swing mirror control parameter on-orbit automatic calibration device is provided, comprising:

[0058] One or more processors;

[0059] A storage device configured to store one or more programs,

[0060] When the one or more programs are executed by the one or more processors, the one or more processors implement the scanning laser radar MEMS swing mirror control parameter on-orbit automatic calibration method of the first aspect.

[0061] According to a fourth aspect of the present application, a readable storage medium is provided, which stores a computer program that is executed by a processor to implement the scanning laser radar MEMS swing mirror control parameter on-orbit automatic calibration method of the first aspect.

[0062] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described device and equipment can refer to the corresponding process in the foregoing method, and will not be described here.

[0063] In several embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other manners. For example, the described apparatus embodiments are merely schematic. For example, the division of the modules is merely a logical function division. There can be another division manner for the actual implementation. For example, a plurality of modules or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections can be indirect couplings or communication connections through some interfaces, devices or modules, and can be in electrical, mechanical or other forms.

[0064] In addition, each functional module in the present application can be integrated in one device, or each module can be physically present alone, or two or more modules can be integrated in one device. The integrated system can be realized in the form of hardware or in the form of a software functional unit.

[0065] When the integrated device is realized in the form of a software functional module and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0066] Those skilled in the art should realize that the functions described in the present application can be realized by hardware, software, firmware or any combination thereof. When realized by software, these functions can be stored in a computer readable medium or transmitted as one or more instructions or codes on a computer readable medium. The computer readable medium includes a computer storage medium and a communication medium, wherein the communication medium includes any medium that facilitates the transmission of a computer program from one place to another. The storage medium can be any available medium that can be accessed by a general or special purpose computer.

[0067] Example 1

[0068] A scanning laser radar MEMS swing mirror control parameter on-orbit automatic calibration method, as shown in Figure 1 The steps are as follows:

[0069] (1) Establish the reference point of the mirror control parameters, the number of reference points in each angle direction is not less than 5, for the laser radar in this project, the input value range of the MEMS mirror control quantity is [0, 4095], the value 2048 is taken as the center input value of the MEMS mirror control quantity, and the other reference points are symmetrically distributed around the value 2048, the selected reference points in the pitch direction are (1048, 1548, 2048, 2548, 3248), and the selected reference points in the azimuth direction are (1048, 1548, 2048, 2548, 3248);

[0070] (2) According to the product data update period, select the appropriate single-point measurement residence time, the single-point measurement residence time in this project is selected to be two data update periods 320ms, and the measurement time of five pairs of reference points is 1600ms;

[0071] (3) Configure the laser radar measurement parameters, including the measurement distance threshold value of the laser, the frequency of the laser, the bias angle of the laser, and the scaling coefficient of the laser, in this project, the lower limit value of the measurement distance threshold of the laser is set to zero, the upper limit of the measurement distance threshold of the laser is set to the maximum ranging value, the scaling coefficient of the laser is set to 10, and the frequency of the laser is set to 40kHz;

[0072] (4) According to the reference points set in the first step, control the mirror to reach the corresponding angle position in turn and stay for a period of time, so that the mirror is in a stable state, and the corresponding angle A / D value is recorded, in this project, the number of buffer variables in the running system is set to 20, the buffer variables in the azimuth angle direction are set to 10, the buffer variables in the pitch angle direction are set to 10, the recorded MEMS angle output values in the azimuth angle direction are (3759, 5783, 7808, 9832, 12660), and the recorded MEMS angle output values in the pitch angle direction are (4021, 5837, 7654, 9471, 12015);

[0073] (5) Data processing and analysis, establish a suitable fitting model, fit the data according to the measurement data of the fourth step, and obtain the model parameter value, in this project, the fitting model adopts a linear model, as shown in the following formula,

[0074] y1=a1x1+b1 (1)

[0075] y2=a2x2+b2 (2)

[0076] Wherein, y1, y2 respectively represent the control input quantity of MEMS in two directions (azimuth direction, elevation direction), x1, x2 respectively represent the angle output quantity of MEMS in two directions, a1, a2, b1, b2 are model coefficients, the relationship between MEMS swing mirror control quantity and angle output quantity is processed according to the fitting model formula by using the least square method, and the fitting parameter values are respectively,

[0077] a1=0.2471

[0078] a2=0.2752

[0079] b1=118.7

[0080] b2=-58.45

[0081] The fitting curve of data is as shown in Figure 2 、 Figure 3

[0082] (6) Model data binding, the parameter values obtained in the fifth step are loaded into the processor for real-time processing application by the processor.

[0083] Using the method in the application, as shown in Figure 4 , the MEMS swing mirror DA-AD curve can be quickly and automatically corrected to the vicinity of the ideal MEMS swing mirror DA-AD curve under ground experiment or on-orbit working conditions, so that the laser radar is more accurate in pointing and tracking targets. Figure 5 As shown in Figure 5 , before correcting the MEMS swing mirror DA-AD curve, the corresponding relationship model parameters of the MEMS angle measurement quantity and the MEMS swing mirror control quantity have a large difference from the ideal parameters, so that the laser radar cannot control the MEMS swing mirror to the appropriate position, and the measured target is in the center position of the field of view.After correction by the method, accurate pointing and tracking of the laser radar target is realized, and the target is in the center position of the field of view of the laser radar.

[0084] The calibration method of the application is simple and fast, does not need the intervention and preparation of an external calibration field, can replace the calibration model and update the parameters at any time according to the pointing condition of the MEMS swing mirror controlled light beam under ground or on-orbit working conditions, and increases the flexibility of the standard update of the MEMS swing mirror control parameters. The application realizes the on-orbit automatic calibration of the MEMS swing mirror control parameters, can correct the MEMS swing mirror control parameters in time according to the change of external environmental factors, and ensures the pointing accuracy of the laser beam.

[0085] The present application is described in detail above in connection with specific embodiments and exemplary examples, but the description is not to be construed to limit the present application. It will be understood by those skilled in the art that various equivalents, modifications and substitutions can be made to the present application and its embodiments without departing from the spirit and scope of the present application, and these are to be construed to fall within the scope of the present application. The scope of the present application is defined by the appended claims.

[0086] The contents not described in detail in the specification of the present application are known to those skilled in the art.

Claims

1. A method for automatic on-orbit calibration of control parameters of a MEMS scanning lidar mirror, characterized in that, The steps include the following: S1. Based on the application range of the mirror and the maximum deflection angle range of the mirror, establish reference points for the mirror control parameters; the number of reference points in each angular direction shall not be less than 5, and the number of reference points shall be symmetrically distributed with respect to the center point of the mirror control quantity. In terms of the distribution interval, the weight of the commonly used field of view in the center shall not be less than the weight of the edge field of view. S2, select the single-point measurement dwell time according to the update cycle of the MEMS tilting mirror nominal deflection angle data; the single-point measurement dwell time is greater than the update cycle of the MEMS tilting mirror nominal deflection angle data. S3, Configure the measurement parameters of the calibration lidar, including the measurement distance threshold of the lidar, the frequency of the lidar, the offset angle of the lidar, and the scaling factor of the lidar; the lower limit of the measurement distance threshold of the lidar is set to zero, and the upper limit is set to the maximum ranging value, so that all scanning points are identified as valid scanning points; the scaling factor of the lidar ensures that the scanning points of a frame of lidar are concentrated within the offset angle range. S4. After receiving ground instructions or according to the preset calibration time, control the pendulum mirror to reach the corresponding angle position in sequence according to the reference point set in step S1 and stop at a single point to measure the dwell time, so that the pendulum mirror is in a stable state and the corresponding angle A / D value is recorded. S5. Establish a fitting model. Based on the angle A / D value obtained in step S4, fit the data to obtain the model parameter values. Specifically, establish a fitting model based on the input and output characteristics of the MEMS pendulum mirror control quantity. The fitting model is a linear fitting model or a polynomial fitting model. The least squares method is used for data fitting. S6. Load the model parameter values ​​obtained in step S5 into the processor in orbit for real-time processing and application.

2. The method for automatic on-orbit calibration of control parameters of a scanning lidar MEMS tilting mirror according to claim 1, characterized in that, The single-point measurement dwell time is 2 to 5 MEMS mirror nominal deflection angle data update cycles.

3. The method for automatic on-orbit calibration of control parameters of a scanning lidar MEMS tilting mirror according to claim 1, characterized in that, In step S6, the step of loading the parameter values ​​obtained in step S5 into the processor in orbit includes modifying the fitting model of the MEMS mirror by injecting instructions and modifying the specific values ​​of the fitting model parameters.

4. An on-orbit automatic calibration device for control parameters of a scanning lidar MEMS tilting mirror, characterized in that, include: The reference point selection module is used to establish reference points for the control parameters of the mirror based on the application range and maximum mirror deflection angle range. The number of reference points in both the azimuth and pitch directions is no less than 5. The number of reference points is symmetrically distributed with respect to the center point of the mirror control quantity. In terms of the distribution interval, the weight of the commonly used field of view in the center is no less than the weight of the edge field of view. The single-point measurement dwell time determination module is used to select the single-point measurement dwell time based on the update cycle of the MEMS tilting mirror nominal deflection angle data. The single-point measurement dwell time is greater than the update cycle of the MEMS tilting mirror nominal deflection angle data; The lidar measurement parameter determination module is used to configure the measurement parameters of the lidar during calibration, including the measurement distance threshold of the laser, the frequency of the laser, the offset angle of the laser, and the scaling factor of the laser. The lower limit of the measurement distance threshold of the laser is set to zero, and the upper limit is set to the maximum ranging value, so that all scanning points are identified as valid scanning points. The scaling factor of the laser ensures that the scanning points of a frame of laser are concentrated within the offset angle range. The ground command receiving module is used to receive ground commands and drive the fitting model setting module. The A / D value measurement module is used to control the pendulum mirror to reach the corresponding angle position in sequence according to the set reference point and stop at a single point to measure the dwell time, so that the pendulum mirror is in a stable state and the corresponding angle A / D value is recorded. The fitting model setting module is used to fit the data based on the obtained angle A / D values ​​to obtain model parameter values. Specifically, a fitting model is established based on the input and output characteristics of the MEMS pendulum mirror control quantity. The fitting model is either a linear fitting model or a polynomial fitting model, and the least squares method is used for data fitting. The loading module is used to load the obtained model parameter values ​​into the processor in orbit for real-time processing and application.

5. An on-orbit automatic calibration device for control parameters of a scanning lidar MEMS tilting mirror, characterized in that, include: One or more processors; Storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the on-orbit automatic calibration method for the control parameters of the scanning lidar MEMS tilting mirror as described in any one of claims 1 to 3.

6. A readable storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the on-orbit automatic calibration method for the control parameters of the scanning lidar MEMS tilting mirror as described in any one of claims 1 to 3.

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