An insertion optical positioning device and positioning method

Abstract

The application provides an optical positioning device and a positioning method. The optical positioning device comprises a light emitter, a light receiver and a prism. The light emitter and the light receiver are located on the same side of a detection area, and the prism is located on the other side of the detection area. The prism is used for collimating light emitted from the light emitter into parallel light and reflecting the parallel light into the light receiver. The optical positioning device provided by the application has the advantages of simple structure, low manufacturing cost, small space occupation, high positioning accuracy (up to sub-pixel level), high positioning speed, and low assembly requirement of the light emitter and the light receiver.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of positioning of industrial automation motion systems, and particularly relates to an insertion type optical positioning device and a positioning method. BACKGROUND

[0002] In systems with motion mechanisms, the motion mechanisms need to be positioned, such as positioning of a linear slide coordinate origin in an automation device, positioning of an initial position of a robot hand, etc. The positioning methods are usually mechanical limiting, positioning by using a distance measuring sensor or an industrial camera, and optical positioning.

[0003] The mechanical limiting is a contact type positioning, and has poor positioning accuracy, and long time use can cause wear of the mechanism, further reducing the positioning accuracy. The positioning by using a distance measuring sensor or an industrial camera has high cost, is complex to use, occupies large space, and has slow response speed.

[0004] The optical positioning generally uses a slot switch, when the motion mechanism or the detected object blocks the optical axis of the slot switch, the slot switch outputs a signal to a control system, and the motion of the motion mechanism or the detected object is stopped.

[0005] Figure 1 A common optical positioning device is shown in FIG. 1. A detection optical axis 2' is located in a slot switch 1', and there is only one detection optical axis 2'. A motion mechanism 4' slides on a guide rail 5' which is fixed between two brackets 6'. In addition, the motion mechanism 4' has an occlusion 3' for occluding the detection optical axis 2'. In the process of the motion mechanism 4' (or the occlusion 3' on the motion mechanism 4') approaching the detection optical axis, no matter how much the occlusion 3' occludes the detection optical axis 2', the slot switch 1' will output a signal to the control system to stop the motion of the motion mechanism or the detected object. However, the detection optical axis 2' of the slot switch 1' is not a single point light, but a light beam with a certain diameter range, and there is a delay from the slot switch outputting the signal to the control system to control the motion mechanism 4' or the occlusion 3' to stop. Thus, the single point positioning by using the slot switch has low positioning accuracy. Moreover, the motion mechanism 4' or the occlusion 3' needs to move back and forth to find the detection optical axis 2' of the slot switch, and when approaching the detection optical axis 2', the motion speed is slowed down, thereby affecting the positioning speed and indirectly affecting the operation speed and work efficiency of the device.

[0006] Patent document CN201811295843.3 discloses an optical positioning device with multiple light emitters and multiple light receivers. The light emitters and the light receivers are respectively installed on different side walls of a groove, and the positional relationship between them is one-to-one correspondence. When the detection object moves in the groove, some light receivers receive the light emitted by multiple light emitters, and the position of the detection object is determined according to the state of the light received by the light receivers. This method can improve the positioning accuracy to some extent. It does not need to search for the optical axis back and forth, and it also speeds up the positioning to some extent. However, multiple light emitters and light receivers are required, which increases the production cost. In addition, the positional correspondence relationship between the light emitters and the light receivers is required to be high, and if there is deviation, it will affect the measurement accuracy. In addition, when the detection object is at the intermediate position of the two light emitters, the device still cannot accurately determine the precise position of the detection object.

[0007] It can be seen that the existing optical positioning device has low positioning accuracy and high assembly requirements for light emitters and light receivers. SUMMARY

[0008] Therefore, in order to further improve the positioning accuracy and reduce the assembly requirements for light emitters and light receivers, the application provides an insertion type optical positioning device.

[0009] The technical scheme of the application is as follows:

[0010] The application provides an optical positioning device, which comprises a light emitter, a light receiver and a prism. The light emitter and the light receiver are located on the same side of a detection area, and the prism is located on the other side of the detection area. The prism is used for collimating the light emitted by the light emitter into parallel light and reflecting it into the light receiver.

[0011] In the above-mentioned optical positioning device, the light receiver is a one-dimensional image sensor.

[0012] In particular, in the above-mentioned optical positioning device, the prism comprises an incident surface, an exit surface, a first reflection surface and a second reflection surface. The incident surface is connected with the exit surface and is located on one side of the prism. The first reflection surface and the second reflection surface are 90° and are respectively located on the other two sides of the prism. The incident surface is convex outward in the shape of a convex lens, which is used for collimating the light emitted by the light emitter into parallel light. The parallel light is reflected by the first reflection surface and the second reflection surface in sequence and then emitted from the exit surface.

[0013] Further, in the above-mentioned optical positioning device, the principal axis of the incident surface is parallel to the perpendicular line of the exit surface.

[0014] Further, in the above-mentioned optical positioning device, the prism is integrally formed.

[0015] Further, the optical positioning device has the light emitter and the light receiver arranged on the same circuit board.

[0016] The optical positioning device has the light emitter being a LED point light source or a laser emitter.

[0017] Further, the optical positioning device has a housing, the circuit board and the prism are fixed at two ends of the housing respectively, the light emitter faces the incident plane, the light receiver faces the exit plane, and the detection area is located between the light receiver and the exit plane, and the detected object can move back and forth in the detection area.

[0018] Further, the optical positioning device has a baffle arranged between the light emitter and the light receiver and extending to the joint of the incident plane and the exit plane in the direction of the prism to prevent the light emitted from the light emitter from directly entering the detection area.

[0019] Further, the optical positioning device has a filter arranged in front of the light receiver and facing the detection area.

[0020] Further, the optical positioning device has the length direction of the one-dimensional sensor being parallel to the moving direction of the detected object.

[0021] In particular, the optical positioning device has a lead port arranged on the housing, and the signal line is connected to the circuit board through the lead port.

[0022] On the other hand, the application provides an optical positioning system with plug-in type, which comprises a control system and the optical positioning device, the control system is connected with the optical positioning device in communication to obtain a projection image, read the gray value of the pixel on the projection image, and calculate the position of the detected object.

[0023] The optical positioning device and the positioning system with plug-in type provided by the application have the following advantages:

[0024] 1. The light emitter and the light receiver which need wiring are arranged on the same side or the same circuit board, the signal line can be led out from one lead port, which provides a convenient and flexible wiring mode, and reduces the position precision requirement of the light emitter and the light receiver during assembly.

[0025] 2. The whole positioning device only needs one light emitter and one light receiver, which has simple structure, small space occupation, and saves manufacturing cost.

[0026] 3. When the detection object enters the detection area, it will block the light beam from the exit plane, thus forming a projection image on the light receiver. Because parallel light is used, the size and position of the projection indirectly reflect the size and position of the detection object. Compared with single-point positioning, the detection object does not need to move back and forth to find the optical axis, thus improving the positioning speed; and no matter the depth of the detection object entering the detection area, the position of the detection object can be accurately positioned.

[0027] 4. A one-dimensional image sensor is used as the light receiver, and the control system determines the position of the detection object through the projection image. Compared with multi-point positioning, the positioning accuracy can reach the pixel level.

[0028] 5. The projection image obtained by the projection method has clear edges and uniform pixel signal strength, and is not affected by the uneven reflection of the surface of the detection object.

[0029] On the other hand, in order to improve the positioning speed and positioning accuracy, the application provides an insertion type optical positioning method.

[0030] The technical scheme of the application is as follows:

[0031] The application provides a positioning method using the above optical positioning device, and the specific method comprises:

[0032] The light emitter emits light;

[0033] The light receiver is exposed;

[0034] The projection image is obtained;

[0035] The gray value of each pixel on the projection image is read, and the position of the detection object is determined according to the gray value of each pixel.

[0036] Further, in the above positioning method, before the projection image is obtained, the exposure time of the light receiver is extended to fully expose the light receiver.

[0037] Further, in the above positioning method, when the gray value of the pixel on the projection image is read,

[0038] the pixel signal strength V n-1 at the fully illuminated position is read;

[0039] the pixel signal strength V n+1 of the projection area is read;

[0040] the pixel signal strength V n at the projection boundary is read;

[0041] The pixel offset d is calculated, and the pixel offset d satisfies:

[0042]

[0043] wherein D is a single pixel size.

[0044] Further, in the positioning method, when judging the position of the detected object, the number of the projection boundaries is judged.

[0045] If the number of the projection boundaries is 1, the edge position P1 of the detected object is calculated, and P1 satisfies:

[0046] P1 = d + (a-1)*D

[0047] wherein a is the sum of the number of the pixels in the projection region and the number of the pixels at the projection boundaries, counted from the direction in which the detected object extends into the detection region.

[0048] If the number of the projection boundaries is 2, the center position P2 of the detected object is calculated, and P2 satisfies:

[0049]

[0050] wherein,

[0051] a1 is the number of the pixels counted from the direction in which the detected object extends into the detection region to the first projection boundary, including the pixel at the first projection boundary.

[0052] d1 is the pixel offset of the first projection boundary.

[0053] a2 is the number of the pixels counted from the direction in which the detected object extends into the detection region to the second projection boundary, including the pixel at the second projection boundary.

[0054] d2 is the pixel offset of the second projection boundary.

[0055] The optical positioning method provided by the present application can accurately position the position of the detected object by reading the gray value (signal intensity) of the pixel, and the positioning precision can reach the pixel level.

[0056] In addition, the optical positioning method provided by the present application can calculate the pixel signal intensity ratio at the projection boundary, so as to calculate the pixel offset; when the position of the detected object is determined, the pixel offset is considered, and the positioning precision can be further improved to the sub-pixel level.

[0057] Furthermore, the optical positioning method provided by the present application can realize edge positioning, and can calculate the center position by recognizing two edges of the detected object, so as to realize center positioning. BRIEF DESCRIPTION OF DRAWINGS

[0058] In order to make the technical solutions in the specific embodiments or prior art of the present application clearer, the accompanying drawings needed in the specific embodiments or prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and all other embodiments obtained by a person of ordinary skill in the art without any creative effort on the basis of the embodiments in the present application shall fall within the protection scope of the present application.

[0059] Figure 1 A schematic diagram of a common slot switch single-point optical positioning device.

[0060] Figure 2 A schematic diagram of an optical positioning device provided by an embodiment of the present application;

[0061] Figure 3 A perspective view of an optical positioning device provided by an embodiment of the present application;

[0062] Figure 4 A schematic diagram of a prism provided by an embodiment of the present application;

[0063] Figure 5 An optical path diagram of an optical positioning device provided by an embodiment of the present application;

[0064] Figure 6 An optical positioning method provided by an embodiment of the present application;

[0065] Figure 7 A pixel offset calculation principle diagram provided by an embodiment of the present application.

[0066] Explanation of reference signs:

[0067] 1 - light emitter; 2 - circuit board; 3 - shell; 4 - light receiver; 5 - optical filter; 6 - prism; 7 - signal line; 8 - detection area; 9 - mounting hole; 10 - baffle;

[0068] 61 - incident surface; 62 - first reflection plane; 63 - second reflection plane; 64 - exit plane. DETAILED DESCRIPTION

[0069] The technical solutions of the present application will be described clearly and completely in combination with the accompanying drawings. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without any creative effort shall fall within the protection scope of the present application.

[0070] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0071] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as there is no conflict between them.

[0072] Embodiment 1

[0073] Figures 2-5 For the first embodiment of the present application, specifically, Figure 2 The positioning device provided for the first embodiment of the present application is shown schematically, Figure 3 is a perspective view of the positioning device, Figure 4 is a schematic view of the prism, Figure 5 is a light path diagram. The light emitter 1 and the light receiver 4 are arranged on the same circuit board 2, and the positions of the light emitter 1 and the light receiver 4 are reserved on the circuit board 2, which not only avoids fine adjustment of the positions of the light emitter 1 and the light receiver 4 during installation, but also ensures the installation accuracy of the two, in addition, it is also convenient to realize circuit synchronization and optimize the structural design of the positioning device. The circuit board 2 and the prism 6 are located on the two sides of the shell 3 respectively. The light emitted from the light emitter 1 is collimated into a parallel light beam by the prism 6 and reflected into the light receiver 4. The light emitter 1 and the light receiver 4 are arranged on the same side, which avoids the need for precise adjustment of the positional relationship when they are arranged opposite each other, and the parallel light beam enters the light receiver 4 during specific positioning, which increases the error range in the left-right direction during the positional assembly of the two.

[0074] The prism 6 is a combined lens used for collimating and reflecting the light beam. Specifically, the prism 6 includes an incident surface 61, a first reflection plane 62, a second reflection plane 63 and an exit plane 64. Among them, the incident surface 61 is connected with the exit plane 64, located on one side of the prism 6, the first reflection plane 62 and the second reflection plane 63 are 90°, respectively located on the other two sides of the prism 6. The incident surface 61 protrudes outward in the form of a convex lens, used for collimating incident light. In order to obtain a parallel light beam perpendicular to the exit, the principal axis of the incident surface 61 is parallel to the perpendicular line of the exit plane 64. In order to reduce the production cost and assembly error, and improve the positioning accuracy of the positioner, the prism 6 is integrally formed by injection molding.

[0075] The light emitter 1 is arranged opposite to the incident plane 61, and the light receiver 4 is arranged opposite to the exit plane 64. The space between the light receiver 4 and the exit plane 64 is the detection area 8, and the detected object can move back and forth in the detection area 8. The light emitter 1 is a common LED light source or a LED point light source or a laser emitter, and preferably a LED point light source. The LED point light source can obtain good collimation effect, and occupies small space, which is beneficial to the structure and light path design. The light receiver 4 is a one-dimensional image sensor, and preferably a CMOS image sensor, which is convenient for reading the signal of each pixel. The divergent light beam emitted from the light emitter 1 is collimated into a parallel light beam after passing through the incident plane 61. The parallel light beam is reflected by the first reflecting plane 62 and the second reflecting plane 63 arranged at right angles, and the direction of the light beam is deflected by 180°, and then the light beam is emitted to the detection area 8 and the light receiver 4. When there is a detected object in the detection area 8, a projection image with clear edges is formed on the light receiver 4 under the irradiation of the parallel light beam, and the projection image is not affected by the uneven reflection of the surface of the detected object. In order to obtain a better projection image, the length direction of the light receiver 4 is parallel to the moving direction of the detected object. Because the parallel light is used, the size and position of the projection indirectly reflect the size and position of the detected object. Moreover, the detected object does not need to move back and forth to find the optical axis in this process, which improves the positioning speed. In addition, the position of the detected object can be accurately positioned regardless of the depth of the detected object entering the detection area. The light receiver 4 is a one-dimensional image sensor, so the position of the detected object can be judged by reading the gray value or pixel signal intensity of each pixel on the projection image, and the positioning accuracy can reach the pixel level or sub-pixel level.

[0076] In particular, in order to filter out stray light, a filter 5 is arranged in front of the light receiver 4 and faces the detection area 8. In order to prevent the light emitted by the light emitter 1 from directly entering the detection area 8 or the light receiver 4, which affects the quality of the projection image, a baffle 10 is arranged between the light emitter 1 and the light receiver 4 and parallel to the exit direction of the parallel light beam. The baffle 10 extends towards the prism direction to the junction of the incident plane 61 and the exit plane 64.

[0077] Alternatively, in the embodiment of the present application, the light emitter 1 and the light receiver 4 can also not be arranged on the same circuit board, and only the circuit synchronization of the light emitter 1 and the light receiver 4 is required.

[0078] Embodiment 2

[0079] The embodiment provides an optical positioning system, which comprises a control system and the optical positioning device described in the embodiment 1. The control system is used for controlling the operation of the optical positioning device, acquiring a projection image, reading the gray value of a pixel on the projection image, calculating the position of the detected object and controlling the movement of the detected object. The optical positioning system provided by the embodiment can control the movement of the detected object, and can determine whether the detected object moves to a detection area by reading the gray value or signal strength of the pixel on the projection image. If the detected object does not move to the detection area, the movement of the detected object to the detection area can be controlled, the step of searching the optical axis back and forth is reduced, and the positioning speed is improved. If the detected object moves to the detection area, the accurate position of the detected object can be calculated, the positioning accuracy can reach the pixel level or even the sub-pixel level, and the positioning accuracy is greatly improved.

[0080] Embodiment 3

[0081] Figure 6 The optical positioning method provided by the embodiment is used for the optical positioning device in the embodiment 1 or the optical positioning system in the embodiment 2. The method comprises the following steps.

[0082] Power on of the positioning device: the positioning device is connected to the power supply and / or the control system through the signal line, the on-off of the current is realized, and the normal work of the positioning device is prepared.

[0083] Light emission of the light emitter: the light beam emitted by the light emitter 1 is emitted to the incident surface 61, is collimated into a parallel light beam, is totally reflected by the first reflecting surface 62 and the second reflecting surface 63 in sequence, is deflected by 180 degrees in the direction of the light path and is emitted to the detection area 8 and the light receiver 4. In order to obtain a good collimation effect, the light emitter 1 is preferably a LED point light source or a laser emitter.

[0084] Exposure of the light receiver: the exposure of the light receiver is prepared for obtaining the projection image of the detected object. In order to obtain a projection image with clear boundaries and clear pixel signals, the light receiver 4 is preferably a one-dimensional CMOS image sensor.

[0085] Acquisition of the projection image: under the irradiation of the parallel light beam, a one-dimensional projection image is formed on the light receiver 4. Since the parallel light is irradiated, the size and position of the projection indirectly reflect the size and position of the detected object.

[0086] Stopping of the light emission of the light emitter and the exposure of the light receiver: in order to not affect the subsequent position determination, the light emission of the light emitter and the exposure of the light receiver are stopped.

[0087] Reading the gray value or signal intensity of each pixel on the projection image: if the detected object is in the detection area, the pixel in the projection area will output a signal intensity much lower than the fully illuminated area. If a certain pixel is exactly on the boundary of the projection area and the fully illuminated area, the signal intensity of the pixel will also be weakened accordingly. But the amount of light and the pixel signal intensity are proportional, that is, the more light, the stronger the output signal, so the control system can preliminarily judge the position of the detected object by reading the gray value or signal intensity of each pixel on the projection image.

[0088] Judging the number of projection boundaries: on the obtained one-dimensional projection image, the number of projection boundaries is judged according to the gray value of the pixel or the signal intensity of the pixel. If the number of projection boundaries is 1, the edge of the detected object can be positioned according to this boundary; if the number of projection boundaries is 2, the detected object is smaller than the size of the projection area, and the center of the detected object can be positioned according to the two boundaries. In addition, in the actual detection process, there may also be a case that the number of projection boundaries is 0 when judging the projection boundaries. If the number of projection boundaries is 0, it means that the detected object has not entered the detection area 8, at this time, the detected object can be continuously controlled to move towards the detection area 8, and then the above steps are performed.

[0089] Calculating the pixel offset at the projection boundary: since the gray value or signal intensity of the pixel is positively correlated with the amount of light, the pixel offset d can be calculated by comparing the pixel gray value or signal intensity of the fully illuminated area, the projection boundary and the projection area.

[0090]

[0091] Where D is the size of a single pixel, V n-1 is the pixel signal intensity of the fully illuminated area; V n+1 is the pixel signal intensity in the projection area; V n is the pixel signal intensity at the projection boundary. Figure 7 The calculation principle diagram of the pixel offset d is given.

[0092] Calculating the boundary or center position: if the number of projection boundaries is 1, the projection boundary position P1 is calculated, P1 satisfies

[0093] P1 = d + (a-1)*D

[0094] Where a is the count of the direction in which the detected object extends into the detection area 8, and the sum of the number of pixels in the projection area and the pixel at the projection boundary.

[0095] If the number of projection boundaries is 2, the center position P2 of the detected object is calculated, P2 satisfies:

[0096]

[0097] wherein,

[0098] a1 is the number of pixels from the direction of the detected object extending into the detection area 8 to the first projection boundary, including the pixel where the first projection boundary is located;

[0099] d1 is the pixel offset of the first projection boundary;

[0100] a2 is the number of pixels from the direction of the detected object extending into the detection area 8 to the second projection boundary, including the pixel where the second projection boundary is located;

[0101] d2 is the pixel offset of the second projection boundary.

[0102] Upload position information: uploading position information to a control system or other device.

[0103] The positioning method provided by the embodiment can achieve pixel-level positioning accuracy by preliminarily judging the gray value or signal strength of the pixel; further, by calculating the pixel offset, sub-pixel-level positioning accuracy can be achieved. Compared with existing optical positioning devices, the positioning accuracy can be significantly improved, and the positioning time can be saved.

[0104] Obviously, the above embodiments are merely examples for clear illustration, and are not intended to limit the embodiments. Based on the above description, those skilled in the art can make other different forms of changes or modifications. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or modifications derived therefrom are still within the protection scope of the present application.

Claims

1. An optical positioning device comprising a light emitter, a light receiver and a prism, characterized in that, The light emitter and the light receiver are located on the same side of the detection area, and the prism is located on the other side of the detection area; the light emitter and the light receiver are arranged on the same circuit board; the prism collimates the light emitted by the light emitter into parallel light and reflects the parallel light into the light receiver; The prism comprises an incident plane, an exit plane, a first reflection plane and a second reflection plane; the incident plane is connected with the exit plane and located on the same side of the prism; the incident plane is used for collimating the light emitted by the light emitter into parallel light; the parallel light is reflected by the first reflection plane and the second reflection plane in sequence and then is emitted from the exit plane; the main axis of the incident plane is parallel to the perpendicular line of the exit plane to obtain the parallel light beam emitted vertically.

2. The optical positioning device of claim 1, wherein, The light receiver is a one-dimensional image sensor, and the length direction of the one-dimensional image sensor is parallel to the moving direction of the detected object.

3. The optical positioning device according to claim 1 or 2, characterized in that The first reflection plane and the second reflection plane are 90° and are located on the other two sides of the prism respectively; the incident plane is convex outward in a convex lens shape; and the prism is integrally formed.

4. The optical positioning device of claim 3, wherein, The light emitter is an LED point light source or a laser emitter.

5. The optical positioning device of claim 4, wherein, The application further comprises a shell; the circuit board and the prism are fixed at two ends of the shell respectively, wherein the light emitter is arranged to face the incident plane, and the light receiver is arranged to face the exit plane; and the detection area is located between the light receiver and the exit plane, and the detected object can reciprocally move in the detection area.

6. The optical positioning device of claim 5, wherein, A baffle is arranged between the light emitter and the light receiver and parallel to the exit direction of the parallel light, the baffle extends to the joint of the incident plane and the exit plane in the direction of the prism to prevent the light emitted from the light emitter from directly entering the exit plane; and a filter is arranged in front of the light receiver in the direction facing the detection area.

7. An optical positioning system comprising a control system and an optical positioning device according to any one of claims 1-6, characterized in that, The control system is communicatively connected with the optical positioning device to obtain a projection image, read the gray value of a pixel on the projection image, and calculate the position of the detected object according to the gray value of the pixel.

8. An optical positioning method using the optical positioning device according to any one of claims 1 to 6, characterized by, The method comprises: The light emitter emits light; The light receiver is exposed to light; A projection image is obtained; The gray value of a pixel on the projection image is read, and the position of the detected object is determined according to the gray value of the pixel.

9. The optical positioning method according to claim 8, characterized in that, When the gray value of the pixel on the projection image is read: Reading the pixel signal intensity V at full illumination n-1 ; Reading the pixel signal intensity V of the projection area n+1 ; Reading the pixel signal intensity V at the projection boundary n ; The pixel offset d is calculated, and the pixel offset d satisfies: wherein D is the size of a single pixel.

10. The optical positioning method according to claim 9, characterized in that, When the position of the detected object is determined, the number of projection boundaries is determined; If the number of projection boundaries is 1, the edge position P1 of the detected object is located, and P1 satisfies: P1=d+(a-1)*D wherein a is the number of pixels from the direction in which the detected object extends into the detection area to the projection area and the pixel where the projection boundary is located; If the number of projection boundaries is 2, the center position P2 of the detected object is located, and P2 satisfies: wherein a1 is the number of pixels from the direction in which the detected object extends into the detection area to the first projection boundary, including the pixel where the first projection boundary is located; d1 is the pixel offset of the first projection boundary. a2 is the pixel number of the second projection boundary from the direction of the detected object extending into the detection area, including the pixel where the second projection boundary is located; d2 is the pixel offset of the second projection boundary.

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