WO2021092846A1

WO2021092846A1 - Zoom tracking method and system, lens, imaging apparatus and unmanned aerial vehicle

Info

Publication number: WO2021092846A1
Application number: PCT/CN2019/118431
Authority: WO
Inventors: 韩守谦; 潘子逸
Original assignee: 深圳市大疆创新科技有限公司
Priority date: 2019-11-14
Filing date: 2019-11-14
Publication date: 2021-05-20
Also published as: CN112313940A

Abstract

Disclosed are a zoom tracking method and system, a lens, an imaging apparatus and an unmanned aerial vehicle. The zoom tracking method comprises: executing a zoom process, and measuring the object distance of an imaging target in real time during the zoom process (S101); and a zoom lens passing a plurality of zoom positions during the zoom process, and executing the following operations at each zoom position: obtaining the image distance at the zoom position according to the focal length corresponding to the zoom position, the object distance that is measured in real time, and an imaging formula; and a focus lens moving to a focus position corresponding to the image distance (S102).

Description

Zoom tracking method and system, lens, imaging device and unmanned aerial vehicle

Technical field

The present disclosure relates to the field of camera technology, and in particular to a zoom tracking method and system, a lens, an imaging device, and an unmanned aerial vehicle.

Background technique

When shooting with a zoomable imaging device, the focal length of the imaging device can be adjusted according to different subjects. During the zooming process, if you do not change the focus position, you cannot maintain a clear image of the subject. In order to maintain focus during zooming, zoom tracking technology has emerged. Using the zoom tracking technology, the focus position can be changed according to the change of the focal length during the zooming process to achieve the purpose of maintaining a clear image of the subject. The proportional mapping method is an existing zoom tracking technology.

Public content

The present disclosure provides a zoom tracking method, including:

Performing a zooming process in which the object distance of the imaging object is measured in real time during the zooming process;

The zoom lens passes through multiple zoom positions during the zooming process, and performs the following operations at each of the zoom positions:

Obtaining the image distance at the zoom position according to the focal length corresponding to the zoom position, the object distance measured in real time, and an imaging formula;

The focusing lens moves to the focusing position corresponding to the image distance.

The present disclosure also provides a zoom tracking system, including:

The zoom lens passes through multiple zoom positions during the zooming process;

The distance measuring unit is used to measure the object distance of the imaging object in real time during the zooming process;

A processing unit, configured to perform the following operations at each of the zoom positions: obtain the image distance at the zoom position according to the focal length corresponding to the zoom position, the object distance measured in real time, and an imaging formula;

The focusing lens is used to move to the focusing position corresponding to the image distance.

The present disclosure also provides a lens including: the above-mentioned zoom tracking system.

The present disclosure also provides an imaging device, including an imaging device body and the above-mentioned lens, and the lens is fixedly or detachably mounted on the imaging device body.

The present disclosure also provides an unmanned aerial vehicle, including: an unmanned aerial vehicle body, a power device, and the above-mentioned imaging device.

The present disclosure can obtain the image distance and focus position at the zoom position according to the focal length, the object distance and the imaging formula, which eliminates the error magnification problem of the isometric mapping method; and is also effective for high-magnification zoom lenses; when the object distance occurs The precise focus position can still be obtained when changing, which is suitable for scenes where the object distance changes.

Description of the drawings

The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the attached picture:

Figure 1 shows the zoom tracking curve.

Figure 2 is a schematic diagram of the error magnification of the isometric mapping method.

Figure 3 shows the object distance range of a high-magnification zoom lens at different focal lengths.

FIG. 4 is a flowchart of a zoom tracking method according to an embodiment of the disclosure.

Figure 5 shows the change in the position of the zoom lens during zooming.

Figure 6 shows the change in the position of the focus lens during zooming.

FIG. 7 is a flowchart of the focus lens moving to the focus position corresponding to the image distance in the zoom tracking method according to the embodiment of the disclosure.

FIG. 8 is a schematic structural diagram of a zoom tracking system according to an embodiment of the disclosure.

FIG. 9 is a schematic structural diagram of an imaging device according to an embodiment of the disclosure.

FIG. 10 is a schematic structural diagram of an unmanned aerial vehicle according to an embodiment of the disclosure.

Detailed ways

The proportional mapping method is a method of mapping the focus position of the current focal length to the focal position of the target focal length based on the zoom tracking curve and the principle of proportional mapping. Among them, the zoom tracking curve is a curve representing the relationship between the zoom position of the zoom lens and the diagonal position of the focus lens under different object distances.

Figure 1 shows an example of a zoom tracking curve. The zoom tracking curve includes a curve 400 corresponding to the infinity end, a curve 402 corresponding to the nearest end, and curves corresponding to various object distances between the infinity end and the nearest end.

In the zoom tracking process, assuming that the object distance of the subject is between the infinity end and the closest end, at the current zoom position, the corresponding current focus position is P1. At this time, the distance between the current focus position P1 and the nearest end curve 402 is b, and the distance between the infinity end curve 400 and the nearest end curve 402 at the current zoom position is a+b, and thus the ratio b/ of the current focus position P1 is obtained. (a+b).

At the target zoom position after zooming, the distance between the infinite end curve 400 and the closest end curve 402 is a'+b'. In the isometric mapping method, the position P2 where the distance from the closest curve 402 is b'and the ratio of b'to the distance a'+b' is equal to b/(a+b) is taken as the target focus position.

For a zoom lens, the numerical range of the image distance expands as the focal length increases. For example, for a 2x zoom lens, if at the wide end (wide end), the stroke of the focus motor is n, then at the tele end (tele), the stroke of the focus motor is 2×n. As shown in Figure 2, the focus motor has a total of 5 steps in the wide end and 10 steps in the tele end. If the focus position of the wide end (ie the ideal focus position) is at step 4.5, the actual focus position of the focus motor is at step 4. Step or Step 5, that is, the error between the actual focus position and the ideal focus position is 0.5 step. After zooming to the tele end, according to the isometric mapping method, the actual focus position of the focus motor is the 8th or 10th step, and the error between the 9th step and the ideal focus position of the tele end is 1 step, so the focus position error The magnification is doubled (from 0.5 step to 1 step). If it is a 6x zoom lens, as shown in Figure 2, the error will be magnified six times for similar reasons. For high magnification zoom lenses of ten times or tens of times, the error will also be magnified by the corresponding magnification. Therefore, the isometric mapping method has the disadvantage of amplifying errors.

For high-magnification zoom lenses, the range of object distances at different focal lengths varies greatly. Figure 3 shows a lens with a wide end of the closest focusing distance of 0.5m, a hyperfocal distance of 4m, and a tele end of the lens with a shortest focusing distance of 10m and a hyperfocal distance of 1000m. If the lens of FIG. 3 images a subject with an object distance of 8 m at the wide end, the object distance of 8 m corresponds to the infinite end curve 400 in FIG. 1. According to the proportional projection method, after zooming to the tele end, the target focus position is still a point on the infinity end curve 400. However, for the tele end, the object distance of 8 m is smaller than the closest focus distance of the tele end, which corresponds to the closest end curve 402, and the target focus position of the tele end should actually be on the closest end curve 402. Therefore, for a high-magnification zoom lens, the isometric mapping method cannot obtain the correct target focus position and is completely ineffective.

In addition, if the subject and the lens move relative to each other during the zooming process, and the object distance changes, it is difficult for the isometric mapping method to ensure that the focus is maintained during the zooming process, that is, the isometric projection method is not suitable for scenes with varying object distances. At the same time, the proportional projection method also requires the lens to be in focus before zooming, which depends on the focus state before zooming.

In summary, the equal-proportion projection method has the defects of magnification errors, failure of high-magnification zoom lenses, unsuitable scenes with varying object distances, and dependence on the focus state before zooming.

The present disclosure provides a zoom tracking method and a zoom tracking system, as well as a lens, an imaging device and an unmanned aerial vehicle including the zoom tracking system. The zoom tracking method and zoom tracking system of the present disclosure have high accuracy and strong adaptability, and do not have the problem of magnification errors, are suitable for high-magnification zoomable lenses and scenes with varying object distances, and do not rely on the focus state before zooming.

The technical solutions of the present disclosure will be clearly and completely described below in conjunction with the embodiments and the drawings in the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present disclosure.

The zoom tracking method of an embodiment of the present disclosure, referring to FIG. 4, includes:

Step S101: Perform a zooming process, during which the object distance of the imaging object is measured in real time.

Step S102: The zoom lens passes through multiple zoom positions during the zooming process, and performs the following operations at each of the zoom positions:

The image distance at the zoom position is obtained according to the focal length corresponding to the zoom position, the object distance measured in real time, and an imaging formula.

The zoom tracking method of this embodiment is for a zoom lens. The zoomable lens includes a zoom lens and a focus lens, and a zoom lens drive unit and a focus lens drive unit for driving the zoom lens and the focus lens, respectively. Driven by the zoom lens drive unit and the focus lens drive unit, the zoom lens and the focus lens can move along the axis of the lens.

The zooming process of this embodiment will be described below. When performing a zooming process, first obtain the target zoom position of the zoom lens. The target focal length is usually input by the user, and the corresponding target zoom position can be obtained after receiving the target focal length. Then, the current zoom position of the zoom lens is used as the starting zoom position, and the zoom lens driving unit drives the zoom lens to move from the starting zoom position to the target zoom position along the axis of the lens.

During the movement, the zoom lens usually passes through at least one intermediate zoom position, and these intermediate zoom positions are located between the initial zoom position and the target zoom position. For example, in Figure 5, the zoom lens first moves from the initial zoom position to the first zoom position, then from the first zoom position to the second zoom position, and so on, and finally moves to the target zoom position. This embodiment does not limit the number of intermediate zoom positions, and the number is generally determined according to the zoom range, that is, the distance between the initial zoom position and the target zoom position.

For two adjacent zoom positions, the zoom change amount between the next zoom position and the previous zoom position is obtained, and the zoom lens moves by the zoom change amount to reach the next zoom position. For example, in Figure 5, when the zoom lens is moved from the first zoom position to the second zoom position, first obtain the zoom change amount between the second zoom position and the first zoom position, and the zoom lens can move to the second zoom position by moving the zoom change amount . The same is true for other zoom positions, each zoom position is reached through the above-mentioned method.

It should be noted that during the zooming process, the object distance of the shooting object may be fixed or may change, for example, at least one of the shooting object and the shooting device has moved. In this case, the object distances of the various zoom positions are not equal.

After the zoom lens moves to each zoom position after the initial zoom position, the focus position corresponding to the zoom position is determined, and the focus lens drive unit drives the focus lens to move to the focus position, so that the focus lens is in the closed position at the zoom position. Focus state, and then the zoom lens moves to the next zoom position. Repeat the above process until the zoom lens moves to the target zoom position. At this time, the focus lens is also in focus at the target zoom position, and the entire zoom process is completed. For example, in FIG. 6, the focus lens first moves to the first focus position, and then moves from the first focus position to the second focus position, and so on, and finally moves to the target focus position.

In the moving process of the zoom lens, the current focus position is first obtained, and then the focus change amount between the next focus position and the current focus position is obtained. The focus lens moves by the focus change amount to reach the next focus position.

That is to say, the zoom process in this embodiment is a dynamic process. The zoom lens moves one step, and the focus lens moves one step; then the zoom lens moves one more step, and the focus lens also moves one step, and so on until the target focus position is reached. In focus.

In the zoom tracking method of this embodiment, a distance measuring unit is provided on the lens or the imaging device on which the lens is installed. The distance measuring unit measures the object distance of the subject in real time during the aforementioned zooming process. The zoom lens can be at any zoom position. Get the corresponding object distance. In this embodiment, the object distance can be measured in any one or several of the following methods: monocular distance measurement, binocular distance measurement, laser distance measurement, TOF distance measurement, and structured light distance measurement. The foregoing is only an example, this embodiment does not limit the object distance measurement method, and it may also be any other type of method.

The following describes how to obtain the corresponding focus position at each zoom position after the initial zoom position, so that the focus lens is in focus at the zoom position.

As described in step S102, at each zoom position, the image distance at the zoom position is obtained according to the focal length corresponding to the zoom position, the object distance measured in real time, and the imaging formula; the focus lens is moved to the corresponding image distance The focus position.

In this embodiment, the imaging formula is a Gaussian imaging formula. The Gaussian imaging formula is:

1/u+1/v=1/f

Among them, u is the object distance, v is the image distance, and f is the focal length.

Specifically, at each zoom position, the focal length f corresponding to the zoom position and the object distance u measured in real time are substituted into the above-mentioned Gaussian imaging formula to obtain the image distance at the zoom position.

For example, when the zoom lens moves to the first zoom position, assuming that the focal length corresponding to the first zoom position is f1, the measured object distance of the subject is u1. Substituting f1 and u1 into the Gaussian imaging formula can be obtained in the first zoom position. Image distance v1 at the zoom position. The same is true for other intermediate zoom positions. When the zoom lens moves to the target zoom position, the image distance at the target zoom position is obtained.

Among them, the zoom position and the focal length f have a fixed correspondence relationship, and this correspondence relationship is determined in advance and stored in the lens. The zoom position can be obtained from a sensor set in the lens or a zoom lens drive unit. After the zoom position is obtained, the focal length f can be obtained through the corresponding relationship.

After the image distance at the zoom position is obtained, the image distance is converted to a focus position, and the focus lens is moved to the focus position.

For example, after the image distance u1 at the first zoom position is obtained, the image distance u1 is converted to the first focus position, and the focus lens is moved to the first focus position, so that the focus lens is in focus. The same is true for other intermediate zoom positions, so that the focus lens is in focus at each intermediate zoom position. When the image distance at the target zoom position is obtained, the focus lens is moved to the target focus position so that the focus lens is in focus at the target zoom position.

Similar to the zoom position and the focal length f, the focus position and the image distance v also have a fixed correspondence relationship, which is determined in advance and stored in the lens. First, the focus position corresponding to the image distance v is obtained according to the corresponding relationship, and then the focus lens driving unit drives the focus lens to move to the focus position.

In this embodiment, the image distance at the zoom position can be obtained in various ways.

As a way, the focal length corresponding to the zoom position and the object distance measured in real time can be directly substituted into the Gaussian imaging formula to calculate the image distance at the zoom position.

As another way, a correspondence table may be prepared in advance according to a Gaussian imaging formula, and the correspondence table reflects the numerical correspondence between the object distance, the focal length, and the image distance, and the correspondence table is stored in the lens. When the image distance needs to be calculated, the correspondence table is read from the lens, and the focal length corresponding to the zoom position and the image at the zoom position corresponding to the object distance measured in real time are found in the correspondence table by looking up the table. distance.

It can be seen that, in the zoom tracking method of this embodiment, at each zoom position, the image distance and focus position at the zoom position can be obtained only according to the focal length and the object distance, instead of focusing on the current focal length like the isometric mapping method. The position is mapped to the focus position of the target focal length. Therefore, the error magnification problem of the isometric mapping method when zooming from the wide end to the tele end is fundamentally eliminated, and the zoom tracking accuracy is greatly improved. For high-magnification zoom lenses, whether on the wide end or the tele end, accurate image distance and focus position can be obtained, so it is also effective for high-magnification zoom lenses. During the entire zooming process, the object distance of the subject may change. Because the zoom tracking method of this embodiment measures the object distance in real time, and the image distance at the zoom position is obtained based on the real-time measurement value of the object distance, even if the object When the distance changes, the precise focus position can still be obtained, so it is suitable for scenes where the object distance changes. And when acquiring the image distance and focus position at the zoom position, it does not depend on the focus state of the zoom position before the zoom position, that is to say, the focus of the next zoom position can be obtained without focusing at the previous zoom position. The location is in focus. As shown in FIG. 6, when acquiring the first focus position, at the initial zoom position, there is no need to focus the focus lens. Therefore, the zoom tracking method of this embodiment has the advantages of small errors, high zoom tracking accuracy, suitable for high-magnification zoom lenses and scenes with varying object distances, and independent of the focus state before zooming.

For a zoom lens, ideally, the corresponding relationship between the focus position and the image distance v should remain unchanged. However, due to the influence of lens consistency, temperature and other factors, in fact, it is difficult to maintain the correspondence between the focus position and the image distance v. For example, the error introduced in the lens manufacturing process makes the correspondence between the focus position and the image distance v of different batches of lenses different. When the temperature of the shooting environment changes drastically, the corresponding relationship between the focus position and the image distance v of the same lens will also change.

In view of the above situation, in the zoom tracking method of this embodiment, after obtaining the image distance at the zoom position, moving the focus lens to the focus position corresponding to the image distance includes the following steps:

Step S201: Correct the focus position corresponding to the image distance according to the calibration coefficient;

Step S202: the focus lens is moved to the corrected focus position.

The calibration coefficient can be determined by calibrating the lens in advance and stored in the lens. The calibration of the lens can be performed in the following manner. Firstly, multiple sets of focus positions and their corresponding image distances are actually measured, and the actually measured multiple sets of focus positions and their corresponding image distances can be fitted to obtain the actual corresponding relationship between the focus positions and the image distance v. Then, the calibration coefficient is obtained according to the difference between the actual corresponding relationship and the theoretical corresponding relationship.

After the focus position corresponding to the image distance is corrected by using the calibration coefficient, the focus position will be more accurate, thereby further improving the accuracy of zoom tracking, and the imaging effect is clearer.

Another embodiment of the present disclosure provides a zoom tracking system, as shown in FIG. 8, including: a zoom lens, a focus lens, a zoom lens drive unit, a focus lens drive unit, a zoom position sensor, a focus position sensor, a distance measuring unit, Processing unit and memory.

The zoom lens passes through multiple zoom positions during zooming.

The distance measuring unit is used to measure the object distance of the imaging object in real time during the zooming process.

The processing unit is configured to perform the following operations at each zoom position: obtain the image distance at the zoom position according to the focal length corresponding to the zoom position, the object distance measured in real time, and an imaging formula.

The focus lens moves to the focus position corresponding to the image distance.

When the zoom tracking system performs a zooming process, it first obtains the target zoom position of the zoom lens. The target focal length is usually input by the user, and the corresponding target zoom position can be obtained after receiving the target focal length. Then, the current zoom position of the zoom lens is used as the starting zoom position, and the zoom lens driving unit drives the zoom lens to move from the starting zoom position to the target zoom position along the axis of the lens.

During the movement, the zoom lens usually passes through at least one intermediate zoom position, and these intermediate zoom positions are located between the initial zoom position and the target zoom position. This embodiment does not limit the number of intermediate zoom positions, and the number is generally determined according to the zoom range, that is, the distance between the initial zoom position and the target zoom position.

For two adjacent zoom positions, the zoom position sensor detects the next zoom position and the previous zoom position, the processing unit calculates the amount of zoom change between the next zoom position and the previous zoom position, and the zoom lens drive unit drives the zoom lens Move the zoom change amount to reach the next zoom position. Through the above method to reach each zoom position.

After the zoom lens moves to each zoom position after the initial zoom position, the focus position corresponding to the zoom position is determined, and the focus lens drive unit drives the focus lens to move to the focus position, so that the focus lens is in the closed position at the zoom position. Focus state, and then the zoom lens moves to the next zoom position. Repeat the above process until the zoom lens moves to the target zoom position. At this time, the focus lens is also in focus at the target zoom position, and the entire zoom process is completed.

During the movement of the zoom lens, the focus position sensor obtains the current focus position and the next focus position, the processing unit calculates the focus change amount between the next focus position and the current focus position, and the focus lens drive unit drives the focus lens to move the focus change amount. Can reach the next focus position.

In the zoom tracking system of this embodiment, the distance measuring unit measures the object distance of the shooting object in real time during the above-mentioned zooming process, and the zoom lens can obtain the corresponding object distance at any zoom position. The distance measuring unit of this embodiment may be one or more of the following: a monocular distance measuring camera, a binocular vision camera, a lidar, a TOF distance meter, and a structured light distance meter. The foregoing is only an example, this embodiment does not limit the specific type of the ranging unit, and it may also be any other type of ranging unit.

The processing unit performs the following operations at each zoom position: obtaining the image distance at the zoom position according to the focal length corresponding to the zoom position, the object distance measured in real time, and the imaging formula. The focus lens moves to the focus position corresponding to the image distance.

1/u+1/v=1/f

Specifically, at each zoom position, the processing unit substitutes the focal length f corresponding to the zoom position and the object distance u measured in real time into the above-mentioned Gaussian imaging formula to obtain the image distance at the zoom position.

For example, when the zoom lens moves to the first zoom position, assuming that the focal length corresponding to the first zoom position is f1, the object distance measured by the distance measuring unit is u1, and the processing unit substitutes f1 and u1 into the Gaussian imaging formula, namely The image distance v1 at the first zoom position can be obtained. The same is true for other intermediate zoom positions. When the zoom lens moves to the target zoom position, the image distance at the target zoom position is obtained.

Wherein, the zoom position and the focal length f have a fixed correspondence relationship, and this correspondence relationship is determined in advance and stored in the memory. After the zoom position sensor detects the zoom position, the processing unit reads the corresponding relationship from the memory, and the focal length f can be obtained through the corresponding relationship.

After obtaining the image distance at the zoom position, the processing unit converts the image distance into a focus position, and the focus lens driving unit moves the focus lens to the focus position. After the processing unit obtains the image distance at the target focus position, the focus lens driving unit moves the focus lens to the target focus position so that the focus lens is in focus at the target zoom position.

Similar to the zoom position and the focal length f, the focus position and the image distance v also have a fixed correspondence relationship, which is determined in advance and stored in the memory. The processing unit reads the correspondence relationship from the memory, obtains the focus position corresponding to the image distance v according to the correspondence relationship, and then the focus lens driving unit drives the focus lens to move the focus position.

As a way, the processing unit may directly substitute the focal length corresponding to the zoom position and the object distance measured in real time into the Gaussian imaging formula to calculate the image distance at the zoom position.

As another way, a correspondence table may be prepared in advance according to a Gaussian imaging formula, and the correspondence table reflects the numerical correspondence between the object distance, the focal length, and the image distance, and the correspondence table is stored in the memory. When the image distance needs to be calculated, the processing unit reads the correspondence table from the memory, and finds the focal length corresponding to the zoom position and the zoom position corresponding to the object distance measured in real time in the correspondence table by looking up the table. The image distance.

It can be seen that, in the zoom tracking system of this embodiment, at each zoom position, the image distance and focus position at the zoom position can be obtained only according to the focal length and the object distance, instead of focusing on the current focal length like the isometric mapping method. The position is mapped to the focus position of the target focal length. Therefore, the error magnification problem of the isometric mapping method when zooming from the wide end to the tele end is fundamentally eliminated, and the zoom tracking accuracy is greatly improved. For high-magnification zoom lenses, whether on the wide end or the tele end, accurate image distance and focus position can be obtained, so it is also effective for high-magnification zoom lenses. During the entire zooming process, the object distance of the subject may change. Because the zoom tracking system of this embodiment measures the object distance in real time, and the image distance at the zoom position is obtained based on the real-time measurement value of the object distance, even if the object When the distance changes, the precise focus position can still be obtained, so it is suitable for scenes where the object distance changes. And when acquiring the image distance and focus position at the zoom position, it does not depend on the focus state of the zoom position before the zoom position, that is to say, the focus of the next zoom position can be obtained without focusing at the previous zoom position. The location is in focus. Therefore, the zoom tracking method of this embodiment has the advantages of small errors, high zoom tracking accuracy, suitable for high-magnification zoom lenses and scenes with varying object distances, and independent of the focus state before zooming.

In the zoom tracking system of this embodiment, the processing unit corrects the focus position corresponding to the image distance according to the calibration coefficient, and the focus lens driving unit drives the focus lens to move to the corrected focus position.

The calibration coefficient can be determined by calibrating the lens in advance and stored in the memory. The calibration of the lens can be performed in the following manner. Firstly, multiple sets of focus positions and their corresponding image distances are actually measured, and the actually measured multiple sets of focus positions and their corresponding image distances can be fitted to obtain the actual corresponding relationship between the focus positions and the image distance v. Then, the calibration coefficient is obtained according to the difference between the actual corresponding relationship and the theoretical corresponding relationship.

It should be noted that the memory is a non-volatile memory. The memory may include: at least one of EPROM, EEPROM, FLASH and other memories.

The zoom lens does not refer to a single lens, but a group of lenses, and this group of lenses includes at least one lens. At least part of the at least one lens is a movable lens. Driven by the zoom lens drive unit, at least part of the lens can move along the axial direction of the lens, thereby changing the focal length of the lens.

The focus lens also does not refer to a single lens, but a group of lenses, and this group of lenses includes at least one lens. At least part of the at least one lens is a movable lens. Driven by the focusing lens drive unit, at least part of the lens can move along the axial direction of the lens, thereby changing the focus position of the lens.

The zoom lens driving unit may include a transmission part and an actuator. The actuator may include a stepper motor. Transmission components may include components such as cam rings. The stepping motor drives the zoom lens to move along the axis of the lens through components such as cam rings.

The focus lens driving unit may include a transmission part and an actuator. The actuator may include a stepper motor. Transmission components may include components such as cam rings. The stepping motor drives the focusing lens to move along the axis of the lens through components such as cam rings.

The processing unit may include any type of data processing device with data processing capabilities, such as but not limited to CPU, DSP, FPGA, CPLD, etc.

Another embodiment of the present disclosure provides a lens including a lens barrel and the zoom tracking system of the previous embodiment.

Yet another embodiment of the present disclosure provides an imaging device, as shown in FIG. 9, comprising: an imaging device body and the lens of the previous embodiment, the lens being fixedly or detachably mounted on the imaging device body .

Yet another embodiment of the present disclosure provides an unmanned aerial vehicle, including: an unmanned aerial vehicle body, a power device, a pan/tilt, and the imaging device of the foregoing embodiments. The pan/tilt is mounted on the drone body, and the imaging device is mounted on the pan/tilt.

Those skilled in the art can clearly understand that for the convenience and conciseness of the description, only the division of the above-mentioned functional modules is used as an example. In practical applications, the above-mentioned functions can be allocated by different functional modules as required, that is, the device The internal structure is divided into different functional modules to complete all or part of the functions described above. For the specific working process of the device described above, reference may be made to the corresponding process in the foregoing method embodiment, which will not be repeated here.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, not to limit it; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; in the case of no conflict, the features in the embodiments of the present disclosure can be combined arbitrarily; and these modifications or replacements It does not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

A zoom tracking method, characterized in that it comprises:

Performing a zooming process, and measuring the object distance of the imaging object in real time during the zooming process;

The zoom lens passes through multiple zoom positions during the zooming process, and performs the following operations at each of the zoom positions:

Obtaining the image distance at the zoom position according to the focal length corresponding to the zoom position, the object distance measured in real time, and an imaging formula;

The focusing lens moves to the focusing position corresponding to the image distance.
The zoom tracking method according to claim 1, wherein the imaging formula is a Gaussian imaging formula.
The zoom tracking method according to claim 1, wherein the object distance of the imaging object is measured in real time by at least one of the following methods: monocular ranging, binocular ranging, laser ranging, TOF ranging , Structured light ranging.
The zoom tracking method according to claim 1, wherein the object distance changes during the zooming process, so that the object distances at at least some of the multiple zoom positions are not equal.
The zoom tracking method of claim 1, wherein the zoom lens passes through multiple zoom positions during the zooming process, including:

For two adjacent zoom positions, obtain the zoom change amount between the next zoom position and the previous zoom position;

The zoom lens moves by the zoom change amount to reach the next zoom position.
The zoom tracking method of claim 1, wherein the moving the focus lens to the focus position corresponding to the image distance comprises:

Get the current focus position;

Acquiring a focus change amount between the focus position corresponding to the image distance and the current focus position;

The focus lens moves by the focus change amount to reach a focus position corresponding to the image distance.
The zoom tracking method according to claim 1, wherein the multiple zoom positions sequentially include: a starting zoom position, at least one intermediate zoom position, and a target zoom position.
The zoom tracking method of claim 1, wherein the moving the focus lens to the focus position corresponding to the image distance comprises:

Correcting the focus position corresponding to the image distance according to the calibration coefficient;

The focus lens moves to the corrected focus position.
The zoom tracking method of claim 1, wherein the obtaining the image distance at the zoom position according to the focal length corresponding to the zoom position, the object distance measured in real time, and an imaging formula includes:

The focal length corresponding to the zoom position and the object distance measured in real time are substituted into the imaging formula to calculate the image distance at the zoom position.
The zoom tracking method of claim 1, wherein the obtaining the image distance at the zoom position according to the focal length corresponding to the zoom position, the object distance measured in real time, and an imaging formula includes:

Reading a correspondence table of object distance, focal length and image distance, the correspondence table being determined according to the imaging formula;

Look up the correspondence table, and determine the focal length corresponding to the zoom position and the image distance at the zoom position corresponding to the object distance measured in real time.
A zoom tracking system, which is characterized in that it comprises:

The zoom lens passes through multiple zoom positions during the zooming process;

The distance measuring unit is used to measure the object distance of the imaging object in real time during the zooming process;

A processing unit, configured to perform the following operations at each of the zoom positions: obtain the image distance at the zoom position according to the focal length corresponding to the zoom position, the object distance measured in real time, and an imaging formula;

The focusing lens is used to move to the focusing position corresponding to the image distance.
The zoom tracking system of claim 11, wherein the imaging formula is a Gaussian imaging formula.
The zoom tracking system of claim 11, wherein the distance measurement unit comprises at least one of the following: a monocular rangefinder camera, a binocular vision camera, a lidar, a TOF rangefinder, a structured light rangefinder .
The zoom tracking system according to claim 11, wherein the object distance changes during the zooming process, so that the object distances at at least a part of the multiple zoom positions are not equal.
The zoom tracking system of claim 11, further comprising:

The zoom position sensor is used to obtain the next zoom position and the previous zoom position of two adjacent zoom positions;

Acquiring, by the processing unit, the amount of zoom change between the next zoom position and the previous zoom position;

The zoom lens driving unit is used to drive the zoom lens to move the zoom change amount to reach the next zoom position.
The zoom tracking system of claim 11, further comprising:

Focus position sensor, used to obtain the current focus position;

Acquiring, by the processing unit, the amount of focus change between the focus position corresponding to the image distance and the current focus position;

The focus lens driving unit drives the focus lens to move the focus change amount to reach the focus position corresponding to the image distance.
The zoom tracking system according to claim 11, wherein the multiple zoom positions sequentially include: a starting zoom position, at least one intermediate zoom position, and a target zoom position.
The zoom tracking system of claim 11, wherein the processing unit further corrects the focus position corresponding to the image distance according to a calibration coefficient;

The focus lens moves to the corrected focus position.
The zoom tracking system of claim 11, wherein the processing unit substitutes the focal length corresponding to the zoom position and the object distance measured in real time into the imaging formula to calculate the image at the zoom position distance.
The zoom tracking system according to claim 11, wherein the processing unit reads a correspondence table of object distance, focal length, and image distance, and the correspondence table is determined according to the imaging formula, and the correspondence relationship is searched. Table to determine the focal length corresponding to the zoom position and the image distance at the zoom position corresponding to the object distance measured in real time.
A lens, characterized by comprising: the zoom tracking system according to any one of claims 11 to 20.
An imaging device, characterized by comprising an imaging device body and the lens of claim 21, the lens being fixedly or detachably mounted on the imaging device body.
An unmanned aerial vehicle, characterized by comprising: an unmanned aerial vehicle body, a power device, and the imaging device according to claim 22.
The drone according to claim 23, further comprising: a pan/tilt; the pan/tilt is installed on the body of the drone, and the imaging device is mounted on the pan/tilt.