TOF camera calibration method and TOF camera calibration device

Abstract

The present invention relates to a calibration method for a TOF camera and a calibration device for a TOF camera. The calibration method for a TOF camera comprises the following steps: fixing a TOF camera and a calibration plate so that a fixed distance d0 is provided between the TOF camera and the calibration plate; adjusting the phase difference of the TOF camera to a first phase difference #imgabs0# and obtaining a first measurement distance d1 through the TOF camera; adjusting the phase difference of the TOF camera to a second phase difference #imgabs1# and obtaining a second measurement distance d2 through the TOF camera; performing several measurement steps to obtain a third measurement distance d3 to an nth measurement distance d n ; Calculate the moving distance △d corresponding to the TOF camera under the second phase difference #imgabs2#; Calculate the actual distance according to the moving distance △d; Calibrate the TOF camera based on the corresponding relationship between the measured distance and the actual distance. The present invention reduces the calibration cost of the TOF camera, shortens the calibration time of the TOF camera, and improves the calibration accuracy of the TOF camera.

Description

Technical Field

[0001] The present invention relates to the technical field of TOF ranging, and in particular to a calibration method and a calibration device for a TOF camera. Background Art

[0002] Before using a TOF (Time of Flight) camera for distance measurement, it is necessary to calibrate the accuracy of the TOF camera's distance measurement to reduce or eliminate the measurement error caused by the measurement accuracy of the TOF camera itself. Currently, there are two main ways to calibrate a TOF camera, namely, a method of using a track to move the calibration plate and a method of using multiple calibration plates at different distances. Among them, the method of using a track to move the calibration plate is to move the position of the calibration plate along a track multiple times during the calibration process, so that the calibration plate is at different distances from the TOF camera to be calibrated, and the TOF camera is calibrated using the correlation between the distance measured by the TOF camera and the actual distance. The method of using multiple calibration plates at different distances is to fix the position of the TOF camera to be calibrated, and set multiple calibration plates with different distances on the TOF camera, so that the TOF camera has multiple distances with the multiple calibration plates, and the TOF camera is calibrated using the correlation between the distance measured by the TOF camera and the actual distance (that is, the actual distance between the TOF camera and each calibration plate).

[0003] However, in the method of using a track to move the calibration plate, the cost of the track and the moving equipment is high, which increases the calibration cost of the TOF camera. Moreover, in the method of using a track to move the calibration plate, the more times it moves, the better the accuracy of the TOF camera calibration, but the corresponding time spent is also more. In addition, in the process of moving the calibration plate through the track, the angle between the TOF camera and the calibration plate may change, affecting the accuracy of the calibration data, and then affecting the calibration accuracy of the TOF camera. The method of using multiple calibration plates at different distances requires the use of equipment with complex structures, such as the need to stably fix each calibration plate, which greatly increases the difficulty of calibration. In addition, the method of using multiple calibration plates at different distances can only be calibrated for a single module, which limits the application of this calibration method.

[0004] Therefore, how to reduce the calibration cost of TOF cameras, reduce the calibration time of TOF, improve the calibration efficiency of TOF cameras, and improve the calibration accuracy of TOF cameras is a technical problem that needs to be solved urgently. Summary of the invention

[0005] The present invention provides a TOF camera calibration method and a TOF camera calibration device, which are used to solve the problems of high calibration cost and long calibration time of existing TOF cameras, so as to improve the calibration efficiency and calibration accuracy of TOF cameras while reducing the TOF camera calibration cost.

[0006] In order to solve the above problems, the present invention provides a TOF camera calibration method, comprising the following steps:

[0007] Fixing the TOF camera and the calibration plate so that there is a fixed distance d0 between the TOF camera and the calibration plate, the TOF camera has a standard measurement range d, and d0<d;

[0008] Adjust the phase difference of the TOF camera to the first phase difference and obtaining the first phase difference through the TOF camera The first measured distance d1 between the TOF camera and the calibration plate is as follows, wherein the first phase difference is 0;

[0009] Adjust the phase difference of the TOF camera to the second phase difference and obtaining the second phase difference by the TOF camera A second measurement distance d2 between the TOF camera and the calibration plate;

[0010] Perform several measurement steps to obtain the third phase difference with the TOF camera To nth phase difference The third measurement distance d3 to the nth measurement distance d3 correspond to each other. n The measuring step includes: adjusting the TOF camera to the xth phase difference And respectively obtain the x-th phase difference through the TOF camera The xth measured distance d between the TOF camera and the calibration plate x ,in x is a positive integer from 3 to n, and n is a positive integer greater than or equal to 3;

[0011] The second phase difference of the TOF camera is calculated by the following formula The corresponding moving distance Δd is:

[0012] Δd=(d×k) / n

[0013] k=(d+d n -d1) / d;

[0014] The first phase difference is calculated based on the moving distance Δd. To nth phase difference The corresponding first actual distance to the nth actual distance between the TOF camera and the calibration plate;

[0015] According to the first measurement distance d1 to the nth measurement distance d n The first actual distance L1 to the nth actual distance L n The correspondence between them is used to calibrate the TOF camera.

[0016] Optionally, the specific steps of fixing the TOF camera and the calibration board include:

[0017] The TOF camera and the calibration plate are fixed along a direction in which an optical axis of a lens of the TOF camera is perpendicular to a calibration plane of the calibration plate.

[0018] Optionally, the visual range of the TOF camera is the entire calibration plane of the calibration plate, and the TOF camera is used to obtain the first phase difference The specific steps of measuring the first distance d1 between the TOF camera and the calibration plate include:

[0019] The TOF camera captures the first phase difference The depth value of several frames under ;

[0020] An average depth value corresponding to depth values ​​of a plurality of frames is calculated, and the average depth value is used as the first measured distance d1.

[0021] Optionally, adjust the phase difference of the TOF camera to a second phase difference The specific steps include:

[0022] Control the modulation signal of the TOF camera to be delayed for a preset time so that the modulation signal and the demodulation signal of the TOF camera have a second phase difference

[0023] Optionally, the specific steps of controlling the modulation signal of the TOF camera to delay a preset time include:

[0024] Setting a delay circuit structure;

[0025] The modulation signal of the TOF camera is controlled to be delayed for a preset time through the delay circuit structure.

[0026] Optionally, the nth measured distance d n Greater than or equal to the standard measuring range d.

[0027] Optionally, according to the first measurement distance d1 to the nth measurement distance d nThe first actual distance L1 to the nth actual distance L n Before calibrating the TOF camera, the following steps are also included:

[0028] Determine the first measurement distance d1 to the nth measurement distance d n , and the first actual distance L1 to the nth actual distance L n Whether there is a distance value exceeding the standard measurement range d, if so, subtract the standard measurement range d from the distance value exceeding the standard measurement range d.

[0029] In order to solve the above problem, the present invention also provides a calibration device for a TOF camera, comprising:

[0030] A fixing module, used for fixing the TOF camera and the calibration plate, so that there is a fixed distance d0 between the TOF camera and the calibration plate, the TOF camera has a standard measurement range d, and d0<d;

[0031] A control module is used to adjust the phase difference of the TOF camera to the first phase difference and obtaining the first phase difference through the TOF camera The first measured distance d1 between the TOF camera and the calibration plate is as follows, wherein the first phase difference The control module is also used to adjust the phase difference of the TOF camera to the second phase difference and obtaining the second phase difference by the TOF camera The control module is also used to perform several measurement steps to obtain a third phase difference with the TOF camera. To nth phase difference The third measurement distance d3 to the nth measurement distance d3 correspond to each other. n The measuring step includes: the control module adjusts the TOF camera to the xth phase difference And respectively obtain the x-th phase difference through the TOF camera The xth measured distance d between the TOF camera and the calibration plate x ,in x is a positive integer from 3 to n, and n is a positive integer greater than or equal to 3;

[0032] The calculation module is used to calculate the second phase difference of the TOF camera by the following formula: The corresponding moving distance Δd is:

[0033] Δd=(d×k) / n

[0034] k=(d+d n -d1) / d;

[0035] A processing module, used to calculate the first phase difference according to the moving distance Δd To nth phase difference The corresponding first actual distance to the nth actual distance between the TOF camera and the calibration plate;

[0036] A calibration module is used to calibrate the first measured distance d1 to the nth measured distance dn and the first actual distance L1 to the nth actual distance Ln according to the first measured distance d1 to the nth measured distance dn. n The correspondence between them is used to calibrate the TOF camera.

[0037] Optionally, the fixing module is used to fix the TOF camera and the calibration plate along a direction in which an optical axis of the lens of the TOF camera is perpendicular to a calibration plane of the calibration plate.

[0038] Optionally, the visual range of the TOF camera is entirely the calibration plane of the calibration plate;

[0039] The control module is used to capture the image at the first phase difference through the TOF camera. The depth values ​​of several frames under the above conditions are obtained, and an average depth value corresponding to the depth values ​​of the several frames is calculated, and the average depth value is used as the first measured distance d1.

[0040] Optionally, the control module is used to control the modulation signal of the TOF camera to be delayed for a preset time, so that the modulation signal and the demodulation signal of the TOF camera have a second phase difference

[0041] Optionally, the control module includes a delay circuit structure, and the delay circuit structure is used to control the modulation signal of the TOF camera to delay a preset time.

[0042] Optionally, the nth measured distance d n Greater than or equal to the standard measuring range d.

[0043] Optionally, also include:

[0044] A judging module is used to judge the first measuring distance d1 to the nth measuring distance d n , and whether there is a distance value exceeding the standard measurement range d among the first actual distance L1 to the nth actual distance Ln, and if so, subtract the standard measurement range d from the distance value exceeding the standard measurement range d.

[0045] The TOF camera calibration method and TOF camera calibration device provided by the present invention achieve the purpose of adjusting the distance between the TOF camera and the calibration plate by adjusting the phase difference of the TOF camera, that is, the movement of the calibration plate or the TOF camera is replaced by adjusting the phase difference of the TOF camera, thereby simplifying the TOF camera calibration steps, reducing the TOF camera calibration cost, shortening the TOF camera calibration time, and improving the TOF camera calibration efficiency. At the same time, since the TOF camera and the calibration plate are both kept fixed during the calibration process, the problem of the angle between the TOF camera and the calibration plate being easily changed during the calibration process is avoided, thereby improving the calibration accuracy of the TOF camera. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Attached Figure 1 is a flow chart of a calibration method for a TOF camera in a specific embodiment of the present invention;

[0047] Attached Figure 2 It is a structural block diagram of a calibration device for a TOF camera in a specific implementation manner of the present invention. DETAILED DESCRIPTION

[0048] The specific implementation manner of the TOF camera calibration method and the TOF camera calibration device provided by the present invention is described in detail below with reference to the accompanying drawings.

[0049] This specific implementation provides a TOF camera calibration method, Figure 1 FIG. 1 is a flow chart of a calibration method for a TOF camera in a specific embodiment of the present invention. Figure 1 As shown, the TOF camera calibration method provided in this specific embodiment includes the following steps:

[0050] Step S11 , fixing the TOF camera and the calibration plate so that there is a fixed distance d0 between the TOF camera and the calibration plate, the TOF camera has a standard measurement range d, and d0<d.

[0051] Specifically, the TOF camera and the calibration plate are fixed respectively so that the distance between the TOF camera and the calibration plate is the fixed distance d0, and during the entire calibration process of the TOF camera, the TOF camera and the calibration plate remain fixed, that is, the physical relative position relationship between the TOF camera and the calibration plate remains unchanged. Those skilled in the art can choose a suitable method to fix the TOF camera and the calibration plate according to actual needs, as long as it can ensure that there is a fixed distance d0 between the TOF camera and the calibration plate. The standard measurement range d refers to the distance range that the TOF camera can accurately measure. When the measured distance exceeds the standard measurement range d of the TOF camera, the TOF camera starts measuring the part exceeding the standard measurement range d again from 0.

[0052] Optionally, the specific steps of fixing the TOF camera and the calibration board include:

[0053] The TOF camera and the calibration plate are fixed along a direction in which an optical axis of a lens of the TOF camera is perpendicular to a calibration plane of the calibration plate.

[0054] Specifically, the calibration plane of the calibration plate is the surface of the calibration plate facing the lens of the TOF camera, that is, the plane of the calibration plate used to reflect the light emitted by the TOF camera. By fixing the TOF camera and the calibration plate in a direction in which the optical axis of the lens of the TOF camera is perpendicular to the calibration plane of the calibration plate, the accuracy of the TOF camera in measuring distance can be improved.

[0055] Step S12, adjusting the phase difference of the TOF camera to the first phase difference and obtaining the first phase difference through the TOF camera The first measured distance d1 between the TOF camera and the calibration plate is as follows, wherein the first phase difference is 0.

[0056] Optionally, the visual range of the TOF camera is the entire calibration plane of the calibration plate, and the TOF camera is used to obtain the first phase difference The specific steps of measuring the first distance d1 between the TOF camera and the calibration plate include:

[0057] The TOF camera captures the first phase difference The depth value of several frames under ;

[0058] An average depth value corresponding to depth values ​​of a plurality of frames is calculated, and the average depth value is used as the first measured distance d1.

[0059] Specifically, first, the TOF camera is adjusted so that the phase difference between the modulation signal and the demodulation signal of the TOF camera is the first phase difference And the first phase difference Afterwards, the TOF camera captures several frames of depth values, and the captured several frames of depth values ​​are the depth information from the TOF camera to the calibration plane of the calibration plate measured by the TOF camera. Then, the depth values ​​of the captured several frames are averaged to obtain the depth information at the first phase difference. The average depth value under the first phase difference The average depth value under the first phase difference is obtained by the TOF camera The first measured distance d1 between the TOF camera and the calibration plate is obtained. The more frames are selected, the more depth value data is obtained, and the higher the accuracy of the first measured distance d1 is obtained; however, if too many frames are selected, the acquisition time of the first measured distance d1 will be prolonged. In this specific embodiment, the TOF camera can capture the depth value of the first phase difference in the first phase difference. The depth values ​​of the next 5 to 20 frames are obtained, thereby obtaining 5 to 20 depth values.

[0060] Step S13, adjusting the phase difference of the TOF camera to the second phase difference and obtaining the second phase difference by the TOF camera The second measured distance d2 between the TOF camera and the calibration plate.

[0061] Optionally, adjust the phase difference of the TOF camera to a second phase difference The specific steps include:

[0062] Control the modulation signal of the TOF camera to be delayed for a preset time so that the modulation signal and the demodulation signal of the TOF camera have a second phase difference

[0063] Optionally, the specific steps of controlling the modulation signal of the TOF camera to delay a preset time include:

[0064] Setting a delay circuit structure;

[0065] The modulation signal of the TOF camera is controlled to be delayed for a preset time through the delay circuit structure.

[0066] Specifically, a delay circuit structure can be added to the circuit board of the TOF camera, and the modulation signal output by the modulation signal sensor inside the TOF camera can be controlled by the delay circuit structure to delay a preset time, thereby controlling the modulation signal of the TOF camera and the demodulation signal of the TOF camera to have a second phase difference. The specific structure of the delay circuit structure can be set by those skilled in the art according to actual needs, as long as the modulation signal of the TOF camera can be controlled to delay the preset time.

[0067] This specific implementation is described by taking the example of setting the delay circuit structure inside the TOF camera. Those skilled in the art may also set the delay circuit structure outside the TOF camera according to actual needs. In addition, those skilled in the art may also control the modulation signal to delay the preset time by software program instead of setting the delay circuit structure according to actual needs.

[0068] When adjusting the phase difference of the TOF camera to the second phase difference Afterwards, a method similar to the measurement method under the first phase difference can be used to control the TOF camera to capture depth values ​​of several frames. Then, the depth values ​​of the captured several frames are averaged to obtain the depth values ​​under the second phase difference. The average depth value under the second phase difference The average depth value under the second phase difference is obtained by the TOF camera The second measured distance d2 between the TOF camera and the calibration plate.

[0069] Step S14, performing several measurement steps to obtain the third phase difference with the TOF camera To nth phase difference The third measurement distance d3 to the nth measurement distance d3 correspond to each other. n The measuring step includes: adjusting the TOF camera to the xth phase difference And respectively obtain the x-th phase difference through the TOF camera The xth measured distance d between the TOF camera and the calibration plate x ,in x is a positive integer from 3 to n, and n is a positive integer greater than or equal to 3.

[0070] For example, the first measurement step is performed: adjusting the TOF camera to the third phase difference and respectively obtain the phase difference at the third phase through the TOF camera The third measurement distance d3 between the TOF camera and the calibration plate is as follows: Perform the second measurement step: adjust the TOF camera to the 4th phase difference and respectively obtain the phase difference at the fourth The fourth measurement distance d4 between the TOF camera and the calibration plate is as follows: Perform the third measurement step: adjust the TOF camera to the 5th phase difference and respectively obtain the phase difference at the 5th The fifth measured distance d5 between the TOF camera and the calibration plate is as follows: And so on, until the (n-2)th measurement step is performed: adjust the TOF camera to the nth phase difference And respectively obtain the phase difference at the nth The nth measured distance d between the TOF camera and the calibration plate n ,in In the process of executing each measurement step, the phase difference can be adjusted in the same manner as the second phase difference, and the measured distance can be obtained in the same manner as the first phase difference.

[0071] Optionally, the nth measured distance d n Greater than or equal to the standard measuring range d.

[0072] Specifically, in order to improve the accuracy and precision of the TOF camera calibration, the measured distance should cover the entire standard measurement range d of the TOF camera, i.e., d1, d2, d3, ..., d n The minimum value of the n measuring distances should be less than or equal to the standard measuring range d, and the maximum value of the n measuring distances should be greater than or equal to the standard measuring range d.

[0073] Step S15, calculating the second phase difference of the TOF camera by the following formula The corresponding moving distance Δd is:

[0074] Δd=(d×k) / n

[0075] k=(d+d n -d1) / d.

[0076] Specifically, first, through the formula k = (d + d n -d1) / d to find the first phase difference To nth phase difference The multiple value k between the phase difference of one cycle (2π). By the formula k=(d+dn -d1) / d can be used to find the maximum phase difference within the measurement range of the TOF camera index = n / k, where n / k is an integer and (n / k) ≤ n. Then, the corresponding phase differences within the measurement range of the TOF camera are selected from the n measurement distances: the first phase difference Second phase difference The third phase difference n / kth phase difference Correspondingly, the measured distance values ​​obtained within the measurement range of the TOF camera are: the first measured distance d1, the second measured distance d2, the third measured distance d3, ..., the n / kth measured distance d n / k .

[0077] Next, according to the ranging principle of the TOF camera, changing the phase difference of the TOF camera is equivalent to adjusting the distance between the TOF camera and the calibration plane of the calibration plate, so the TOF camera at the second phase difference is calculated by the formula Δd = (d × k) / n. The corresponding moving distance Δd is generated below.

[0078] Step S16, calculating the first phase difference according to the moving distance Δd To nth phase difference The corresponding 1st actual distance to the nth actual distance between the TOF camera and the calibration plate.

[0079] Table 1 shows the correspondence between the measured distance and the actual distance under different phase differences. The multiple relationship between them is used to calculate the actual distance corresponding to each phase difference.

[0080] Table 1 Correspondence between measured distance and actual distance under different phase differences

[0081]

[0082] Step S17, according to the first measurement distance d1 to the nth measurement distance d n The first actual distance L1 to the nth actual distance L n The correspondence between them is used to calibrate the TOF camera.

[0083] In order to improve the accuracy of further calibration, optionally, according to the first measurement distance d1 to the nth measurement distance d n The first actual distance L1 to the nth actual distance L n Before calibrating the TOF camera, the following steps are also included:

[0084] Determine the first measurement distance d1 to the nth measurement distance d n , and the first actual distance L1 to the nth actual distance L n Whether there is a distance value exceeding the standard measurement range d, if so, subtract the standard measurement range d from the distance value exceeding the standard measurement range d.

[0085] In addition, this specific embodiment also provides a calibration device for a TOF camera. Figure 2 is a structural block diagram of a TOF camera calibration device in a specific embodiment of the present invention. The TOF camera calibration device provided in this specific embodiment can be used as follows Figure 1 The TOF camera calibration method shown in FIG. Figure 2 As shown, the calibration device of the TOF camera includes:

[0086] A fixing module 20, used for fixing the TOF camera and the calibration plate, so that there is a fixed distance d0 between the TOF camera and the calibration plate, and the TOF camera has a standard measurement range d, and d0<d;

[0087] The control module 21 is used to adjust the phase difference of the TOF camera to the first phase difference. and obtaining the first phase difference through the TOF camera The first measured distance d1 between the TOF camera and the calibration plate is as follows, wherein the first phase difference The control module 21 is also used to adjust the phase difference of the TOF camera to the second phase difference and obtaining the second phase difference by the TOF camera The control module 21 is also used to perform several measurement steps to obtain a third phase difference with the TOF camera. To nth phase difference The third measurement distance d3 to the nth measurement distance d3 correspond to each other. n The measuring step includes: the control module 21 adjusts the TOF camera to the xth phase difference And respectively obtain the x-th phase difference through the TOF camera The xth measured distance d between the TOF camera and the calibration plate x ,in x is a positive integer from 3 to n, and n is a positive integer greater than or equal to 3;

[0088] The calculation module 22 is used to calculate the second phase difference of the TOF camera by the following formula: The corresponding moving distance Δd is:

[0089] Δd=(d×k) / n

[0090] k=(d+d n -d1) / d;

[0091] The processing module 23 is used to calculate the first phase difference according to the moving distance Δd. To nth phase difference The corresponding first actual distance to the nth actual distance between the TOF camera and the calibration plate;

[0092] The calibration module 25 is used to calibrate the first measured distance d1 to the nth measured distance dn and the first actual distance L1 to the nth actual distance Ln according to the first measured distance d1 to the nth measured distance dn. n The correspondence between them is used to calibrate the TOF camera.

[0093] Optionally, the fixing module 20 is used to fix the TOF camera and the calibration plate along a direction in which the optical axis of the lens of the TOF camera is perpendicular to the calibration plane of the calibration plate.

[0094] Optionally, the visual range of the TOF camera is entirely the calibration plane of the calibration plate;

[0095] The control module 21 is used to capture the TOF camera at the first phase difference The depth values ​​of several frames under the above conditions are obtained, and an average depth value corresponding to the depth values ​​of the several frames is calculated, and the average depth value is used as the first measured distance d1.

[0096] Optionally, the control module 21 is used to control the modulation signal of the TOF camera to be delayed for a preset time, so that the modulation signal and the demodulation signal of the TOF camera have a second phase difference

[0097] Optionally, the control module 21 includes a delay circuit structure, and the delay circuit structure is used to control the modulation signal of the TOF camera to delay a preset time.

[0098] Optionally, the nth measured distance d n Greater than or equal to the standard measuring range d.

[0099] Optionally, the calibration device of the TOF camera further includes:

[0100] The judging module 24 is used to judge the first measuring distance d1 to the nth measuring distance d n, and whether there is a distance value exceeding the standard measurement range d among the first actual distance L1 to the nth actual distance Ln, and if so, subtract the standard measurement range d from the distance value exceeding the standard measurement range d.

[0101] The TOF camera calibration method and TOF camera calibration device provided in this specific embodiment achieve the purpose of adjusting the distance between the TOF camera and the calibration plate by adjusting the phase difference of the TOF camera, that is, the movement of the calibration plate or the TOF camera is replaced by adjusting the phase difference of the TOF camera, which simplifies the TOF camera calibration steps, reduces the TOF camera calibration cost, shortens the TOF camera calibration time, and improves the TOF camera calibration efficiency. At the same time, since the TOF camera and the calibration plate are both kept fixed during the calibration process, the problem of the angle between the TOF camera and the calibration plate being easily changed during the calibration process is avoided, thereby improving the calibration accuracy of the TOF camera.

[0102] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A TOF camera calibration method, characterized in that: The steps include: Fixing a TOF camera and a calibration plate so that there is a fixed distance d0 between the TOF camera and the calibration plate, the visual range of the TOF camera is entirely the calibration plane of the calibration plate, the TOF camera has a standard measurement range d, and d0<d, the standard measurement range d refers to the distance range that the TOF camera can accurately measure, and when the measured distance exceeds the standard measurement range d of the TOF camera, the TOF camera starts measuring the part exceeding the standard measurement range d again from 0; Adjusting the phase difference of the TOF camera to a first phase difference φ1, and obtaining, by the TOF camera, a first measurement distance d1 between the TOF camera and the calibration plate at the first phase difference φ1, wherein the first phase difference φ1 is 0; Adjusting the phase difference of the TOF camera to a second phase difference φ2, and acquiring, through the TOF camera, a second measured distance d2 between the TOF camera and the calibration plate at the second phase difference φ2; Perform several measurement steps to obtain the third phase difference φ3 to the nth phase difference φ with the TOF camera. n The third measurement distance d3 to the nth measurement distance d3 correspond to each other. n The measuring step includes: adjusting the TOF camera to the xth phase difference φ x , and respectively obtain the x-th phase difference φ through the TOF camera x The xth measured distance d between the TOF camera and the calibration plate x , where φ x =(x-1)φ2, x is a positive integer from 3 to n, and n is a positive integer greater than or equal to 3; the moving distance △d corresponding to the second phase difference φ2 of the TOF camera is calculated by the following formula: △d=(d×k) / n k=(d+d n -d1) / d; According to the moving distance Δd, the first phase difference φ1 to the nth phase difference φ are calculated respectively. n The corresponding first actual distance to the nth actual distance between the TOF camera and the calibration plate; According to the first measurement distance d1 to the nth measurement distance d n The first actual distance L1 to the nth actual distance L n The TOF camera is calibrated according to the corresponding relationship between them; According to the first measurement distance d1 to the nth measurement distance d n The first actual distance L1 to the nth actual distance L n Before calibrating the TOF camera, the method further comprises the following steps: determining the first measurement distance d1 to the nth measurement distance d n , and the first actual distance L1 to the nth actual distance L n Whether there is a distance value exceeding the standard measurement range d, if so, subtract the standard measurement range d from the distance value exceeding the standard measurement range d.

2. The calibration method of a TOF camera according to claim 1, characterized in that: The specific steps for fixing the TOF camera and the calibration board include: The TOF camera and the calibration plate are fixed along a direction in which an optical axis of a lens of the TOF camera is perpendicular to a calibration plane of the calibration plate.

3. The calibration method of a TOF camera according to claim 1, characterized in that: The specific steps of obtaining the first measured distance d1 between the TOF camera and the calibration plate at the first phase difference φ1 by the TOF camera include: The TOF camera captures depth values ​​of several frames at the first phase difference φ1; calculates an average depth value corresponding to the depth values ​​of the several frames, and uses the average depth value as the first measurement distance d1.

4. The TOF camera calibration method according to claim 1, characterized in that: The specific steps of adjusting the phase difference of the TOF camera to the second phase difference φ2 include: The modulation signal of the TOF camera is controlled to be delayed for a preset time, so that there is a second phase difference φ2 between the modulation signal and the demodulation signal of the TOF camera.

5. The TOF camera calibration method according to claim 4, characterized in that: The specific steps of controlling the modulation signal of the TOF camera to delay a preset time include: Setting a delay circuit structure; The modulation signal of the TOF camera is controlled to be delayed for a preset time through the delay circuit structure.

6. The TOF camera calibration method according to claim 1, characterized in that: The nth measured distance d n Greater than or equal to the standard measuring range d.

7. A TOF camera calibration device, characterized in that: include: A fixing module, used for fixing a TOF camera and a calibration plate, so that there is a fixed distance d0 between the TOF camera and the calibration plate, the visual range of the TOF camera is entirely the calibration plane of the calibration plate, the TOF camera has a standard measurement range d, and d0<d, the standard measurement range d refers to the distance range that the TOF camera can accurately measure, when the measured distance exceeds the standard measurement range d of the TOF camera, the TOF camera starts measuring the part exceeding the standard measurement range d again from 0; A control module, used to adjust the phase difference of the TOF camera to a first phase difference φ1, and obtain a first measured distance d1 between the TOF camera and the calibration plate under the first phase difference φ1 through the TOF camera, wherein the first phase difference φ1 is 0; the control module is also used to adjust the phase difference of the TOF camera to a second phase difference φ2, and obtain a second measured distance d2 between the TOF camera and the calibration plate under the second phase difference φ2 through the TOF camera; the control module is also used to perform several measurement steps to obtain a third phase difference φ3 to an nth phase difference φ4 with the TOF camera n The third measurement distance d3 to the nth measurement distance d3 correspond to each other. n The measuring step includes: the control module adjusts the TOF camera to the xth phase difference φ x , and respectively obtain the x-th phase difference φ through the TOF camera x The xth measured distance d between the TOF camera and the calibration plate x , where φ x =(x-1)φ2, x is a positive integer from 3 to n, and n is a positive integer greater than or equal to 3; The calculation module is used to calculate the moving distance △d corresponding to the second phase difference φ2 of the TOF camera by the following formula: △d=(d×k) / n k=(d+d n -d1) / d; A processing module is used to calculate the first phase difference φ1 to the nth phase difference φ according to the moving distance Δd. n The corresponding first actual distance to the nth actual distance between the TOF camera and the calibration plate; A calibration module is used to calibrate the first measured distance d1 to the nth measured distance d n The first actual distance L1 to the nth actual distance L n The TOF camera is calibrated according to the corresponding relationship between them; A judging module is used to judge the first measuring distance d1 to the nth measuring distance d n , and the first actual distance L1 to the nth actual distance L n Whether there is a distance value exceeding the standard measurement range d, if so, subtract the standard measurement range d from the distance value exceeding the standard measurement range d.

8. The TOF camera calibration device according to claim 7, characterized in that: The fixing module is used to fix the TOF camera and the calibration plate along a direction in which the optical axis of the lens of the TOF camera is perpendicular to the calibration plane of the calibration plate.

9. The TOF camera calibration device according to claim 7, characterized in that: The control module is used to capture depth values ​​of several frames at the first phase difference φ1 through the TOF camera, calculate an average depth value corresponding to the depth values ​​of the several frames, and use the average depth value as the first measurement distance d1.

10. The TOF camera calibration device according to claim 7, characterized in that: The control module is used to control the modulation signal of the TOF camera to be delayed for a preset time, so that there is a second phase difference φ2 between the modulation signal and the demodulation signal of the TOF camera.

11. The TOF camera calibration device according to claim 10, characterized in that: The control module includes a delay circuit structure, and the delay circuit structure is used to control the modulation signal of the TOF camera to delay a preset time.

12. The TOF camera calibration device according to claim 7, characterized in that: The nth measured distance d n Greater than or equal to the standard measuring range d.

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