Motion capture test method, location detection method of occlusion points in motion capture process

Abstract

The present invention discloses a motion capture test method and a method for detecting the position of occluded points in a motion capture process. The method comprises the following steps: collecting the position data of a capture target point and a plurality of capture reference points in a static state of a captured object in an unobstructed space; collecting the position data of the plurality of capture reference points in a dynamic state of a captured object in an obstructed space; fitting the position of the occluded point in the motion capture process according to the collected position data of the plurality of capture reference points in the dynamic state of the captured object in the obstructed space and the position data of the capture target point and the plurality of capture reference points in the static state of the captured object in the unobstructed space. The present invention uses the position data of the captured object in a static state in an unobstructed space to fit the position of the occluded point of the captured object in a dynamic state in an obstructed space, thereby solving the problem of missing position information of the occluded point during motion.

Description

Technical Field

[0001] The present invention relates to the technical field of motion capture, and in particular to a method for detecting a position of an occlusion point in a motion capture process and a motion capture test method. Background Art

[0002] Based on optical motion capture technology, the three-dimensional spatial position of moving objects can be accurately measured. The optical motion capture system includes an infrared camera, an information conversion box, a calibration frame and a reflective ball. The infrared camera is used to transmit and receive infrared light for measurement, the information conversion box is used for signal processing, the calibration frame is used to calibrate the spatial position to establish the spatial relationship of multiple cameras, and the reflective ball is attached to the subject's body. The camera measures the position of the point through infrared light. Due to its accurate and reliable characteristics, this technology is widely used in ergonomics, medical health, sports training and other fields. In the field of ergonomics, optical motion capture technology can measure the body's movements and postures in real time and calculate the body's kinematic data. Its principle is to attach reflective balls to the body's joints, use optical principles to measure the spatial position of each reflective ball, establish a body's kinematic model, and solve the kinematic data. Compared with wearable inertial sensors, optical motion capture systems are more accurate and can arrange more points to capture the differences in movement details of different parts.

[0003] However, for the application scenarios of ergonomics, during the movement, part of the human body may be blocked by an obstruction. At this time, the reflective ball at the blocked position cannot be captured by the system, and the spatial position data of the point disappears, and the movement information of the disappeared part cannot be obtained. If the movement data of the part is the key position point of human-computer interaction, it will bring difficulties to ergonomics analysis. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for detecting the position of occlusion points in a motion capture process, an electronic device and a motion capture test method which can solve the problem of missing position information of occlusion points during motion.

[0005] To achieve the above object, a first aspect of the present invention provides a method for detecting the position of an occlusion point in a motion capture process, comprising the following steps:

[0006] Collect the position data of the capture target point and multiple capture reference points of the captured object in a static state in an unobstructed space;

[0007] Collecting position data of the plurality of capture reference points in a dynamic state of the captured object in the obstructed space;

[0008] The positions of the occluded points in the motion capture process are fitted based on the collected position data of multiple capture reference points in the dynamic state of the captured object in the occluded space, and the position data of the capture target point and the multiple capture reference points in the static state of the captured object in the unobstructed space.

[0009] Further, the position of the occlusion point in the motion capture process is fitted based on the collected position data of multiple capture reference points in the dynamic state of the captured object in the occlusion space, and the position data of the capture target point and the multiple capture reference points in the static state of the captured object in the unobstructed space, including:

[0010] Calculate static distance data between the capture target point and each capture reference point based on position data of the capture target point and the plurality of capture reference points in a static state of the captured object in an unobstructed space;

[0011] Obtain virtual position data of the capture target point in the dynamic state of the captured object according to the static distance data and the position data of the multiple capture reference points in the dynamic state of the captured object in the occluded space;

[0012] Iteratively processing the virtual position data according to a predetermined formula to obtain iterative position data of the capture target point in the dynamic state of the captured object;

[0013] Calculate the dynamic distance data of the capture target point in the dynamic state of the captured object according to the iterative position data and the position data of the multiple capture reference points in the static state of the captured object;

[0014] When the dynamic distance data and the static distance data satisfy a predetermined condition, the iterative position data of the capture target point in the dynamic state is the position of the occlusion point in the dynamic state.

[0015] Further, the predetermined formula is:

[0016]

[0017] in, To capture the coordinates of the target point in a dynamic state, To capture the coordinates of the reference point in a dynamic state, is the distance between the capture target point and the capture reference point in the dynamic state, l MsAs , l MsBs , l MsCs is the distance between the capture target point and the capture reference point in the static state, and k is 0.3~0.5.

[0018] Furthermore, the predetermined condition is:

[0019]

[0020] in, is the distance between the capture target point and the capture reference point in the dynamic state, l MsAs , l MsBs , l MsCs is the distance between the capture target point and the capture reference point in a static state, and a is a predetermined constant.

[0021] A second aspect of the present invention provides an electronic device, comprising:

[0022] one or more processors; and

[0023] A storage device is used to store one or more programs, and when the one or more programs are executed by the one or more processors, the one or more processors implement the position detection method as described in the first aspect.

[0024] A third aspect of the present invention provides a motion capture test method, comprising the following steps:

[0025] Determine the blocked area and the unblocked area according to the relative position of the captured object and the blocking object during the movement of the captured object in the blocked space;

[0026] A position acquisition device is set in the shielded area to correspond to the capture target point, and multiple position acquisition devices are set in the unshielded area to correspond to multiple capture reference points;

[0027] When the captured object is in a static state in an unobstructed space, collecting position data of the capture target point and the multiple capture reference points;

[0028] The position acquisition device provided in the shielding area is removed, and the position data of the multiple capture reference points are acquired when the captured object is in a dynamic state in the shielding space.

[0029] Further, the method further comprises the following steps:

[0030] The position of the occluding point in the dynamic state is fitted based on the collected position data of multiple capture reference points of the captured object in the dynamic state in the occluded space, and the position data of the capture target point and the multiple capture reference points of the captured object in the static state in the unobstructed space.

[0031] Further, the position of the occlusion point in the dynamic state is fitted based on the collected position data of multiple capture reference points of the captured object in the dynamic state in the occluded space, and the position data of the capture target point and the multiple capture reference points of the captured object in the static state in the unobstructed space, including:

[0032] Calculate static distance data between the capture target point and each capture reference point based on position data of the capture target point and the plurality of capture reference points in a static state of the captured object in an unobstructed space;

[0033] Obtain virtual position data of the capture target point in the dynamic state of the captured object according to the static distance data and the position data of the multiple capture reference points in the dynamic state of the captured object in the occluded space;

[0034] Iteratively processing the virtual position data according to a predetermined formula to obtain iterative position data of the capture target point in the dynamic state of the captured object;

[0035] Calculate the dynamic distance data of the capture target point in the dynamic state of the captured object according to the iterative position data and the position data of the multiple capture reference points in the static state of the captured object;

[0036] When the dynamic distance data and the static distance data satisfy a predetermined condition, the iterative position data of the capture target point in the dynamic state is the position of the occlusion point in the dynamic state.

[0037] Further, the predetermined formula is:

[0038]

[0039] in, To capture the coordinates of the target point in a dynamic state, To capture the coordinates of the reference point in a dynamic state, is the distance between the capture target point and the capture reference point in the dynamic state, l MsAs , l MsBs , l MsCs is the distance between the capture target point and the capture reference point in the static state, and k is 0.3~0.5.

[0040] Furthermore, the predetermined condition is:

[0041]

[0042] in, is the distance between the capture target point and the capture reference point in the dynamic state, l MsAs , l MsBs , l MsCs is the distance between the capture target point and the capture reference point in a static state, and a is a predetermined constant.

[0043] The present invention utilizes the position data of the captured object in a static state in an unobstructed space to fit the position of the occlusion point of the captured object in a dynamic state in an occluded space, thereby solving the problem of missing position information of the occlusion point during movement.

[0044] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0046] Figure 1 A schematic diagram of the locations of collection points of a motion capture test method according to an embodiment of the present invention;

[0047] Figure 2 It is a flow chart of a method for detecting the position of an occlusion point in a motion capture process according to an embodiment of the present invention;

[0048] Figure 3 It is a flow chart of a method for detecting the position of an occlusion point in a motion capture process according to another embodiment of the present invention;

[0049] Figure 4 The figure is a flow chart of a motion capture testing method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the present invention will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0051] In addition, the described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present invention. However, those skilled in the art will appreciate that the technical solution of the present invention can be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring various aspects of the present invention.

[0052] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0053] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0054] like Figure 2 As shown, the first aspect of the present invention provides a method for detecting the position of an occlusion point in a motion capture process, comprising the following steps:

[0055] Step S200: Collecting the position data of the capture target point and multiple capture reference points of the captured object in a static state in an unobstructed space. For example, taking the captured object as a human body, Figure 1 Point M is the capture target point, and points A, B, and C are capture reference points. In the occluded space, point M is blocked by the occluder, while points A, B, and C are not blocked. It should be noted that the captured object can be not only a human body, but also an animal or mechanical equipment. The number and position of the capture reference points are not limited to those shown in the figure, and the present invention is not limited thereto. The collected position data can be position coordinates, etc.

[0056] Step S210: Collecting the position data of the multiple capture reference points in the dynamic state of the captured object in the occluded space. Since the capture target point in the dynamic state of the captured object in the occluded space is occluded, the capture reference point is not occluded, and only the position data of the capture reference point in the dynamic state can be collected at this time.

[0057] Step S220: Fit the position of the occlusion point in the motion capture process based on the collected position data of multiple capture reference points in the dynamic state of the captured object in the occluded space, and the position data of the capture target point and the multiple capture reference points in the static state of the captured object in the unobstructed space.

[0058] The present invention utilizes the position data of the captured object in a static state in an unobstructed space to fit the position of the occlusion point of the captured object in a dynamic state in an occluded space, thereby solving the problem of missing position information of the occlusion point during movement.

[0059] like Figure 3 As shown, step S220 may further include steps S221-S225:

[0060] Step S221: Calculate the static distance data between the capture target point and each capture reference point according to the position data of the capture target point and the multiple capture reference points in the static state of the captured object in the unobstructed space. The coordinates of the capture target point in the static state are M s , the coordinates of the three snap reference points are A s , B s , C s, we can calculate the distances l between the capture target point and the three capture reference points MsAs , l MsBs , l MsCs .

[0061] Step S222: Obtain virtual position data of the capture target point in the dynamic state of the captured object based on the static distance data and the position data of the multiple capture reference points in the dynamic state of the captured object in the occluded space. The position data of the capture target point M in the dynamic state of the captured object is missing due to occlusion, and the initial virtual coordinates M of the capture target point M can be set. d , virtual coordinate M d To capture the reference point A coordinate, move it up ncm, where n is generally the distance l from M to A calculated in the static experiment. MsAs It should be noted that the calculation of the initial virtual coordinates of the capture target point M is only an example, and it can also be calculated based on other capture reference points and the relative position relationship between the capture reference point and the capture target point, and the present invention is not limited to this.

[0062] Step S223: iteratively process the virtual position data according to a predetermined formula to obtain iterative position data of the capture target point in the dynamic state of the captured object.

[0063] Continuously iterate M according to the following formula d Point coordinates The k value is 0.3~0.5.

[0064]

[0065] in, To capture the coordinates of the target point in a dynamic state, To capture the coordinates of the reference point in a dynamic state, is the distance between the capture target point and the capture reference point in the dynamic state, l MsAs , l MsBs , l MsCs It is the distance between the capture target point and the capture reference point in static state.

[0066] Step S224: Calculate the dynamic distance data of the capture target point in the dynamic state of the captured object according to the iterative position data and the position data of the multiple capture reference points in the static state of the captured object.

[0067] In the dynamic acquisition results, capture the target point M d The coordinates are Snap reference point A d , B d , C d The coordinates are Calculate the capture target point M dTo three snap reference points A d , B d , C d Distance

[0068] Step S225: When the dynamic distance data and the static distance data satisfy a predetermined condition, the iterative position data of the capture target point in the dynamic state is the position of the occlusion point in the dynamic state.

[0069] When the sum of the dynamic and static distance differences from the target point M to the three reference points A, B, and C is less than a, the error of the calculation result is considered to meet the requirements. The predetermined conditions are as follows:

[0070]

[0071] in, is the distance between the capture target point and the capture reference point in the dynamic state, l MsAs , l MsBs , l MsCs is the distance between the capture target point and the capture reference point in a static state, and a is a predetermined constant.

[0072] If it is within the allowed range, the iteration stops. The smaller a is, the smaller the error is, but the calculation time will be longer. At this time, the coordinates of point M are the estimated values ​​of the coordinates of the occluded point.

[0073] like Figure 4 As shown, the second aspect of the present invention also provides a motion capture test method, comprising the following steps:

[0074] Step S400: Determine the blocked area and the unblocked area according to the relative position between the captured object and the blocking object during the movement of the captured object in the blocked space. Figure 1 As shown, the area where the capture target point M is located is the occluded area, and the capture reference points A, B, and C are the unoccluded area. The occluded area and the unoccluded area are determined according to the relative position of the captured object and the occluder. The occluded area is the area where the captured object is blocked by the occluder, and the unoccluded area is the area where the captured object is not blocked.

[0075] Step S410: a position acquisition device is set in the shielded area to correspond to the capture target point, and multiple position acquisition devices are set in the unshielded area to correspond to multiple capture reference points. The position acquisition device can be a reflective ball, etc., but the present invention is not limited thereto.

[0076] Step S420: When the captured object is in a static state in an unobstructed space, the position data of the capture target point and the multiple capture reference points are collected.

[0077] Step S430: remove the position acquisition device provided in the shielding area, and collect the position data of the multiple capture reference points in the dynamic state of the captured object in the shielding space.

[0078] The motion capture test method of this embodiment also includes the following steps:

[0079] The position of the occlusion point in the dynamic state is fitted based on the collected position data of multiple capture reference points of the captured object in the occlusion space in the dynamic state, and the position data of the capture target point and the multiple capture reference points of the captured object in the unobstructed space in the static state. The occlusion point position detection method and principle of this step have been Figure 2 and Figure 3 The embodiments are described in detail in the embodiments and will not be repeated here.

[0080] The third aspect of the present invention further provides an electronic device, comprising:

[0081] one or more processors; and

[0082] The storage device is used to store one or more programs, and when the one or more programs are executed by the one or more processors, the one or more processors implement the position detection method as described in the first aspect. The position detection method has been described in detail in the above embodiment and will not be repeated here.

[0083] The fourth aspect of the present invention further provides a computer-readable medium, which may be included in the electronic device described in the above embodiment; or may exist independently without being assembled into the electronic device. The above computer-readable medium carries one or more programs, and when the above one or more programs are executed by an electronic device, the electronic device implements the position detection method described in the above embodiment.

[0084] According to an embodiment of the present invention, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present invention includes a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication part, and / or installed from a removable medium. When the computer program is executed by a central processing unit (CPU), the above-mentioned functions defined in the system of the present application are executed.

[0085] It should be noted that the computer-readable medium shown in the present invention may be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, device or device. In the present invention, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries a computer-readable program code. This propagated data signal may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate or transmit a program for use by or in conjunction with an instruction execution system, apparatus or device. The program code contained on the computer-readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wire, optical cable, RF, etc., or any suitable combination of the above.

[0086] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present invention. In this regard, each box in the flow chart or block diagram can represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of a code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flow chart, and the combination of the boxes in the block diagram or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0087] The modules involved in the embodiments of the present invention may be implemented by software or hardware, and the modules described may also be arranged in a processor. The names of these modules do not, in some cases, limit the modules themselves.

[0088] It should be noted that, although several modules or units of the equipment for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to an embodiment of the present invention, the features and functions of two or more modules or units described above can be embodied in one module or unit. On the contrary, the features and functions of one module or unit described above can be further divided into being embodied by multiple modules or units.

[0089] Through the description of the above implementation, it is easy for those skilled in the art to understand that the example implementation described here can be implemented by software, or by software combined with necessary hardware. Therefore, the technical solution according to the implementation of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, including several instructions to enable a computing device (which can be a personal computer, a server, a touch terminal, or a network device, etc.) to execute the method according to the implementation of the present invention.

[0090] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0091] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for detecting the position of an occlusion point in a motion capture process, characterized in that: The steps include: Collect the position data of the capture target point and multiple capture reference points of the captured object in a static state in an unobstructed space; Collecting position data of the plurality of capture reference points in a dynamic state of the captured object in the obstructed space; The position of the occlusion point in the motion capture process is fitted based on the collected position data of multiple capture reference points in the dynamic state of the captured object in the occlusion space, and the position data of the capture target point and the multiple capture reference points in the static state of the captured object in the unobstructed space; The position of the occlusion point in the motion capture process is fitted based on the collected position data of multiple capture reference points in the dynamic state of the captured object in the occlusion space, and the position data of the capture target point and the multiple capture reference points in the static state of the captured object in the unobstructed space, including: Calculate static distance data between the capture target point and each capture reference point based on position data of the capture target point and the plurality of capture reference points in a static state of the captured object in an unobstructed space; Obtain virtual position data of the capture target point in the dynamic state of the captured object according to the static distance data and the position data of the multiple capture reference points in the dynamic state of the captured object in the occluded space; The virtual position data is iteratively processed according to a predetermined formula to obtain iterative position data of the capture target point in the dynamic state of the captured object; the predetermined formula is: in, To capture the coordinates of the target point in a dynamic state, To capture the coordinates of the reference point in a dynamic state, is the distance between the capture target point and the capture reference point in the dynamic state, l MsAs , l MsBs , l MsCs is the distance between the capture target point and the capture reference point in the static state, k is 0.3~0.5; Calculate the dynamic distance data of the capture target point in the dynamic state of the captured object according to the iterative position data and the position data of the multiple capture reference points in the static state of the captured object; When the dynamic distance data and the static distance data meet a predetermined condition, the iterative position data of the capture target point in the dynamic state is the position of the occlusion point in the dynamic state; the predetermined condition is: in, is the distance between the capture target point and the capture reference point in the dynamic state, l MsAs , l MsBs , l MsCs is the distance between the capture target point and the capture reference point in a static state, and a is a predetermined constant.

2. An electronic device, characterized in that: include: one or more processors; as well as A storage device for storing one or more programs, when the one or more programs are executed by the one or more processors, enables the one or more processors to implement the position detection method as claimed in claim 1.

3. The motion capture test method is characterized in that: The steps include: Determine the blocked area and the unblocked area according to the relative position of the captured object and the blocking object during the movement of the captured object in the blocked space; A position acquisition device is set in the shielded area to correspond to the capture target point, and multiple position acquisition devices are set in the unshielded area to correspond to multiple capture reference points; When the captured object is in a static state in an unobstructed space, collecting position data of the capture target point and the multiple capture reference points; Remove the position acquisition device provided in the shielding area, and collect the position data of the multiple capture reference points when the captured object is in a dynamic state in the shielding space; Fitting the position of the occluding point in the dynamic state according to the collected position data of multiple capturing reference points of the captured object in the dynamic state in the occluding space, and the position data of the capturing target point and the multiple capturing reference points of the captured object in the static state in the unobstructed space; Fitting the position of the occlusion point in the dynamic state according to the collected position data of multiple capture reference points of the captured object in the occlusion space in the dynamic state, and the position data of the capture target point and the multiple capture reference points of the captured object in the unobstructed space in the static state includes: Calculate static distance data between the capture target point and each capture reference point based on position data of the capture target point and the plurality of capture reference points in a static state of the captured object in an unobstructed space; Obtain virtual position data of the capture target point in the dynamic state of the captured object according to the static distance data and the position data of the multiple capture reference points in the dynamic state of the captured object in the occluded space; The virtual position data is iteratively processed according to a predetermined formula to obtain iterative position data of the capture target point in the dynamic state of the captured object; the predetermined formula is: in, To capture the coordinates of the target point in a dynamic state, To capture the coordinates of the reference point in a dynamic state, is the distance between the capture target point and the capture reference point in the dynamic state, l MsAs , l MsBs , l MsCs is the distance between the capture target point and the capture reference point in the static state, k is 0.3~0.5; Calculate the dynamic distance data of the capture target point in the dynamic state of the captured object according to the iterative position data and the position data of the multiple capture reference points in the static state of the captured object; When the dynamic distance data and the static distance data meet a predetermined condition, the iterative position data of the capture target point in the dynamic state is the position of the occlusion point in the dynamic state; the predetermined condition is: in, is the distance between the capture target point and the capture reference point in the dynamic state, l MsAs , l MsBs , l MsCs is the distance between the capture target point and the capture reference point in a static state, and a is a predetermined constant.

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