A control method for a multi-segment individually rotatable continuum robot

Abstract

The application provides a control method for a multi-segment independently rotatable continuum robot, comprising the following steps: S1, establishing a forward kinematics model of the continuum robot; S2, solving configuration parameters according to an end pose of the continuum robot; S3, solving length variation of each segment driving wire; S4, performing parameter compensation on structure coupling; S5, performing parameter compensation on driving coupling; and S6, obtaining a target position of a driving variable gear. Through analysis on the continuum robot, coupling caused by mechanical structure is compensated in the solving process of driving parameters to realize decoupling, so that each segment can be independently controlled and does not affect each other, and when the rotation segment is fixed, the movement segment can make the actuator accurately reach a target pose as expected, misoperation in surgery is avoided, and control precision is improved.

Description

Technical Field

[0001] This invention relates to the field of flexible robot control technology, and in particular to a control method for a multi-segment, individually rotatable continuous robot. Background Technology

[0002] With the continuous development of medical technology, surgical procedures are evolving from traditional multi-port laparoscopic surgery to single-port transumbilical laparoscopic surgery and even NOTES (Natural Orifice Transvaginal Surgery). NOTES procedures utilize natural orifices of the body, such as the mouth, urethra, and vagina, to deliver surgical instruments to the target surgical site. For gynecological diseases, transvaginal surgery is more suitable than other approaches. Transvaginal Natural Orifice Transvaginal Endoscopic Surgery (vNOTES) combines transvaginal surgery with endoscopic techniques, providing gynecologists with a completely new surgical approach, offering advantages such as minimal invasiveness and no scarring.

[0003] Currently, common transvaginal natural orifice (TN) surgical instruments mainly fall into two categories: One type consists of purely flexible catheters and other slender medical devices. Their advantage lies in their flexible structure, allowing them to be delivered to the patient's tissues through complex, winding cavities. However, due to a lack of rigidity, these instruments can only perform simple operations, lacking precision and freedom of movement, making them unsuitable for complex surgical tasks such as dissection and suturing. The other type consists of purely rigid instruments with sufficient rigidity to ensure the execution of complex surgical procedures, but their limited space for movement makes operation very difficult. During transvaginal TN endoscopy, the surgical instruments enter through the vagina, while the surgical area is located in the pelvic cavity behind the instruments. This requires the instruments to be rotated at a certain angle for manipulation, and often necessitates delicate operations such as tissue dissection. Therefore, neither the purely rigid nor purely flexible instruments mentioned above are suitable for the needs of this type of surgery.

[0004] Multi-segment nested continuum robots have multiple nested segments, each capable of bending and rotating independently. Complex surgical procedures can be performed at varying rotational angles through the bending and rotational movements of different segments. However, a portion of the nested inner segments must conform to the curvature of the outer segments. This curvature compliance leads to multi-segment coupling effects, causing interference between the motion control of different robot segments. This can introduce errors in the movement of the end effector and even damage other tissues in the patient, necessitating decoupling. To address these issues, it is essential to design and develop a control method for this type of multi-segment, individually rotatable continuum robot suitable for vNOTES. Summary of the Invention

[0005] In view of this, the present invention proposes a control method for a multi-segment rotatable continuum robot that fully considers the coupling between surgical robot segments and decouples them through hierarchical drive compensation.

[0006] The technical solution of this invention is implemented as follows: This invention provides a control method for a multi-segment, individually rotatable continuous robot, comprising:

[0007] S1: Establish the forward kinematics model of the continuum robot;

[0008] S2: Solve for configuration parameters based on the end-effector pose of the continuum robot;

[0009] S3: Solve for the change in length of the driving wire in each segment;

[0010] S4: Perform parameter compensation for structural coupling;

[0011] S5: Perform parameter compensation for drive coupling;

[0012] S6: Obtain the target position of the driving variable gear.

[0013] Based on the above technical solutions, preferably, the continuum robot includes two bendable segments and an end effector. The first bendable segment is a rotary segment, used to achieve large-angle rotation, keeping the second bendable segment and the end effector facing the patient. The second bendable segment is a motion segment, used to allow the end effector to directly contact each patient point based on the positioning of the rotary segment, so as to perform vNOTES surgery. Each segment is provided with a drive wire. The bending motion of each segment is converted into linear motion of the drive wire by a motor-driven gear and a screw transmission mechanism. The rotational motion of each segment is directly driven by the motor-driven gear through gear meshing.

[0014] Preferably, the step S1 of establishing the forward kinematics model of the continuum robot involves constructing coordinate systems O0X0Y0Z0, O1X1Y1Z1, O2X2Y2Z2, O3X3Y3Z3, O4X4Y4Z4, and O5X5Y5Z5 for the reference position, the rotary segment, the rigid connection between the rotary segment and the motion segment, the motion segment, the rigid connection between the motion segment and the end effector, and the end effector, respectively; Let For the (i+1)th coordinate system O i+1 X i+1 Y i+1 Z i+1 Relative to the i-th coordinate system O i X i Y i Z i The transformation matrix, It describes the change in the reference position of the rotating segment relative to the continuous robot; This describes the transformation matrix of the rigid connection between the rotating segment and the moving segment relative to the rotating segment. This describes the transformation matrix of the moving segment relative to the rotating segment and the rigid connection between the moving segment and the rotating segment. This describes the transformation matrix between the rigid connection between the moving segment and the end effector and the moving segment. The transformation matrix described is the transformation matrix of the end effector relative to the rigid connection between the motion segment and the end effector; then the pose T of the end effector relative to the reference position of the continuum robot is expressed as:

[0015]

[0016]

[0017] In the above expression, s represents the sine function sin, c represents the cosine function cos, and θ1 represents the bending angle of the rotation segment; θ represents the rotation angle of the rotating segment about Z0 of the coordinate system O0X0Y0Z0; l1 is the length of the rotating segment; lu1 is the length of the rigid connection between the rotating segment and the moving segment; θ2 represents the bending angle of the moving segment. l2 represents the rotation angle of the moving segment around Z2 of the coordinate system O2X2Y2Z2; l2 is the length of the moving segment; lu2 is the length of the rigid connection between the moving segment and the end effector. l3 represents the rotation angle of the end effector around Z4 of the coordinate system O4X4Y4Z4; l3 is the length of the end effector.

[0018] More preferably, in step S2, the configuration parameters are solved based on the end-effector pose of the continuum robot by letting parameters l1, l2, l3, lu1, and lu2 be known; and letting parameters θ1, θ2, ... and For the unknown configuration parameters to be solved; the pose T of the end effector relative to the reference position of the continuum robot is rewritten as the following homogeneous transformation matrix: Where p x p y and p z This indicates the position of the origin of coordinate system O5X5Y5Z5 within coordinate system O0X0Y0Z0; n x n y and n z a represents the unit vector of the X5 axis of coordinate system O5X5Y5Z5 in coordinate system O0X0Y0Z0; x a y and a z b represents the unit vector of the Y5 axis of coordinate system O5X5Y5Z5 in coordinate system O0X0Y0Z0; x b yand b z Let Z5 be the unit vector of the Z5 axis in coordinate system O5X5Y5Z5 in coordinate system O0X0Y0Z0; by taking the inverse of the alignment transformation matrix, the configuration parameters θ1 and θ2 of the end effector pose of the continuum robot can be obtained. and

[0019] More preferably, in step S3, the calculation of the change in length of the driving wire in each segment is performed by letting d1 be the offset of the driving wire from the center of the segment's cross-section in the rotating segment; then, in the rotating segment, the change in length of the driving wire Δl 10 =d1θ1; In the motion segment, let d2 be the offset of the driving wire from the center of the segment's cross-section, and let Δl be the change in the length of the driving wire. 20 =d2θ2.

[0020] More preferably, the parameter compensation for structural coupling in step S4 involves the following: For the moving segment, a portion of its length lies within the rotating segment. When the rotating segment is in a bent state, the length of the driving wire in that portion of the moving segment changes accordingly. This type of coupling needs to be decoupled, and the change is compensated for in the length of the driving wire. The change in the length of the driving wire after parameter compensation for structural coupling is:

[0021] In a further preferred embodiment, the parameter compensation for the drive coupling described in step S5 is to eliminate the bending of the corresponding segment caused by the linear motion tension of the drive wire. When the corresponding rotating gear rotates clockwise while the corresponding bent gear remains stationary, for the screw drive mechanism, this is equivalent to the bent gear experiencing a counterclockwise rotational drive coupling effect. To decouple the bending gear, the corresponding bent gear moves simultaneously with the corresponding rotating gear. The parameter compensation for this is as follows: Where k is the transmission ratio of the lead screw drive mechanism.

[0022] More preferably, in step S6, obtaining the target position of the driving variable gear means that, for the rotary segment, the rotation of the corresponding gear directly causes the segment to rotate; for the moving segment, when the rotary segment's corresponding gear moves clockwise while the moving segment's corresponding gear is stationary, it is equivalent to the moving segment's corresponding gear moving counterclockwise. After compensating for the coupling effects of the bending and rotational motions one by one, a set of driving variables is obtained: The aforementioned driving variables correspond to the target positions of a set of gears.

[0023] The present invention provides a control method for a multi-segment, individually rotatable continuous robot, which has the following advantages compared to the prior art:

[0024] (1) This method decouples the segments by hierarchical drive compensation, realizing independent control of each segment and offsetting the coupling effect by the coordinated cooperation of multiple drive units.

[0025] (2) Current common solutions rely on expensive external measuring equipment or sensors to track and control the end effector pose of the continuum robot. Furthermore, the robotic arm of the surgical robot is a consumable and needs to be replaced after a certain number of surgeries, requiring reconfiguration and recalibration of the corresponding measuring equipment or sensors. Additionally, surgical robots performing transoral surgeries are relatively small, making it difficult to integrate sensors and other measuring equipment systems into the surgical system, thus limiting their versatility. This method departs from the traditional compensation method's reliance on hardware sensors. It starts from the causes of error, analyzing and compensating for each factor contributing to the error, thereby solving the problem of inaccurate positioning. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart of a control method for a multi-segment, individually rotatable continuum robot according to the present invention;

[0028] Figure 2 This is a schematic diagram illustrating the establishment of coordinate systems for different positions of multiple segments in a control method for a multi-segment rotatable continuous robot according to the present invention.

[0029] Figure 3 This is a schematic diagram showing the rotation angle or bending angle of each segment in a control method for a multi-segment rotatable continuum robot according to the present invention.

[0030] Figure 4 This is a schematic diagram illustrating parameter compensation for structural coupling in a control method for a multi-segment, independently rotatable continuous robot according to the present invention. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] like Figures 1-4 As shown, the present invention provides a control method for a multi-segment, individually rotatable continuous robot, comprising:

[0033] S1: Establish the forward kinematics model of the continuum robot.

[0034] like Figure 2 As shown, the continuum robot of this scheme includes two bendable segments and an end effector. The first bendable segment is a rotary segment, used to achieve large-angle rotation, keeping the second bendable segment and the end effector facing the patient. The second bendable segment is a motion segment, used to allow the end effector to directly contact each patient point based on the positioning of the rotary segment, so as to perform vNOTES surgery. Each segment is equipped with a drive wire. The bending motion of each segment is converted into linear motion of the drive wire by a motor-driven gear and a screw transmission mechanism. The rotational motion of each segment is directly driven by the motor-driven gear through gear meshing.

[0035] The step of establishing the forward kinematics model of the continuum robot is based on... Figure 2 The coordinate system origin is used to construct coordinate systems O0X0Y0Z0, O1X1Y1Z1, O2X2Y2Z2, O3X3Y3Z3, O4X4Y4Z4, and O5X5Y5Z5 for the reference position, rotary segment, rigid connection between rotary segment and motion segment, motion segment, rigid connection between motion segment and end effector, and end effector, respectively. The origin of coordinate system O0X0Y0Z0 is located at the center of the end of rotary segment away from motion segment. The origin of coordinate system O2X2Y2Z2 is located at the center of the end of the rotary section near the center of the moving section; the origin of coordinate system O3X3Y3Z3 is located at the center of the end of the moving section away from the end actuator; the origin of coordinate system O4X4Y4Z4 is located at the center of the end of the moving section near the end actuator; and the origin of coordinate system O5X5Y5Z5 is located at the center of the end of the end actuator away from the moving section.

[0036] make For the (i+1)th coordinate system O i+1 X i+1 Y i+1 Z i+1 Relative to the i-th coordinate system O i X i Y i Z i The transformation matrix, It describes the change in the reference position of the rotating segment relative to the continuous robot; This describes the transformation matrix of the rigid connection between the rotating segment and the moving segment relative to the rotating segment. This describes the transformation matrix of the moving segment relative to the rotating segment and the rigid connection between the moving segment and the rotating segment. This describes the transformation matrix between the rigid connection between the moving segment and the end effector and the moving segment. The transformation matrix described is the transformation matrix of the end effector relative to the rigid connection between the motion segment and the end effector; then the pose T of the end effector relative to the reference position of the continuum robot is expressed as:

[0037]

[0038]

[0039]

[0040]

[0041] In the above expression, s represents the abbreviation of the sine function sin, c represents the abbreviation of the cosine function cos, and θ1 represents the bending angle of the rotation segment. θ represents the rotation angle of the rotating segment about Z0 of the coordinate system O0X0Y0Z0; l1 is the length of the rotating segment, that is, the axial length in the direction of the moving segment; lu1 is the length of the rigid connection between the rotating segment and the moving segment; θ2 represents the bending angle of the moving segment. l2 represents the rotation angle of the moving segment around Z2 of the coordinate system O2X2Y2Z2; l2 is the length of the moving segment; lu2 is the length of the rigid connection between the moving segment and the end effector. l3 represents the rotation angle of the end effector around Z4 of the coordinate system O4X4Y4Z4; l3 is the length of the end effector.

[0042] S2: Solve for configuration parameters based on the end-effector pose of the continuum robot.

[0043] The specific steps for solving the configuration parameters based on the end-effector pose of the continuum robot are as follows: Let parameters l1, l2, l3, lu1, and lu2 be known; let parameters θ1, θ2, ... and For the unknown configuration parameters to be solved; the pose T of the end effector relative to the reference position of the continuum robot is rewritten as the following homogeneous transformation matrix: Where p x p y and p z This indicates the position of the origin of coordinate system O5X5Y5Z5 within coordinate system O0X0Y0Z0; n x n yand n z a represents the unit vector of the X5 axis of coordinate system O5X5Y5Z5 in coordinate system O0X0Y0Z0; x a y and a z b represents the unit vector of the Y5 axis of coordinate system O5X5Y5Z5 in coordinate system O0X0Y0Z0; x b y and b z Let Z5 be the unit vector of the Z5 axis in coordinate system O5X5Y5Z5 in coordinate system O0X0Y0Z0; by taking the inverse of the alignment transformation matrix, the configuration parameters θ1 and θ2 of the end effector pose of the continuum robot can be obtained. and

[0044] S3: Solve for the change in length of the driving wire in each segment.

[0045] More preferably, in step S3, the calculation of the change in length of each segment of the drive wire is performed by setting the lengths of the two drive wires inside the rotating segment to be: In the rotary section, the lengths of the two drive wires are l respectively. 1A and l 1B Let d1 be the offset of the driving wire from the center of the segment's cross-section in the rotating segment; combining the above two equations, we can see that the change in the length of the driving wire Δl in the rotating segment is... 10 =d1θ1.

[0046] During the motion segment, let the lengths of the two drive wires inside be... The total lengths of the two drive wires in the motion segment are l. 2A and l 2B d2 is the offset of the driving wire from the center of the segment's cross-section during the motion segment. Combining the two equations above, we can see that the change in the length of the driving wire Δl during the motion segment is... 20 =d2θ2.

[0047] In summary, neglecting coupling effects, the change in the length of the driving wire in each segment is:

[0048] Δl 10 =d1θ1;Δl 20 =d2θ2.

[0049] S4: Perform parameter compensation for structural coupling.

[0050] Parameter compensation for structural coupling is necessary because a portion of the moving section is within the rotation section, and the curvature of the drive wire in this portion is affected by the rotation section. This type of coupling needs to be decoupled, and the change is compensated in the length of the drive wire.

[0051] like Figure 4 As shown, the motion segment rotates △ The angle affects the length of the drive wire in the moving segment. Compensating for this change within the drive wire length, the lengths of the two drive wires within the moving segment are:

[0052] Combining the above two equations and the conclusion of step S3, the change in the length of the driving wire after parameter compensation for the structural coupling is: Δl 10 =d1θ1;

[0053] S5: Perform parameter compensation for drive coupling;

[0054] In this embodiment, both the bending and rotational motions of each segment are driven by a motor-driven gear transmission. The rotating gear and its corresponding controlled segment are integrated; gear rotation directly causes the corresponding segment to rotate. The bending gear converts gear rotation into linear motion of the driving wire via a lead screw transmission mechanism, and the tension of the driving wire's linear motion causes the corresponding segment to bend. When the rotating gear rotates clockwise while the bending gear remains stationary, for the lead screw transmission mechanism, this is equivalent to the bending gear rotating counterclockwise. To eliminate this driving coupling effect, the bending gear should move simultaneously with the rotating gear for decoupling. This also leads to changes in the driving wire of each segment, and parameter compensation is performed as follows:

[0055] Where k is the transmission ratio of the lead screw drive mechanism.

[0056] S6: Obtain the target position of the driving variable gear.

[0057] In this embodiment, the final driving variable is the target position of a set of gears. In order to achieve the final control of the continuum robot, it is necessary to convert the compensation of the change in the driving wire of each segment into a driving variable.

[0058] For the rotary segment, the rotation of the corresponding gear directly causes the segment to rotate; for the kinematic segment, when the rotary gear rotates clockwise while the kinematic gear remains stationary, it is equivalent to the kinematic gear rotating counterclockwise. After compensating for the coupling effects of the bending and rotational motions one by one, a set of driving variables is obtained:

[0059] We obtain a set of driving variables: It is important to note that the driving variables obtained above are the absolute values ​​of a set of drive unit positions, not the amount of motion required for each drive unit. In other words, what is obtained is the target position of a set of gears, not the amount of rotation required for each gear. The amount of motion of the drive unit needs to be obtained by subtracting the encoder feedback value from the drive parameters calculated by this method.

[0060] This solution analyzes the structure of the continuum robot and compensates for the coupling caused by the mechanical structure during the solution of the driving parameters to achieve decoupling. This allows each segment to be controlled independently without affecting each other. When the rotary segment is fixed, the motion segment enables the actuator to accurately reach the target pose as expected, avoiding misoperation during surgery and improving control accuracy.

[0061] By analyzing the drive structure and compensating for the coupling caused by the drive structure during the solution of drive parameters, decoupling is achieved, allowing each gear to control its corresponding segment degree of freedom without causing unintended effects on other degrees of freedom, thus improving control independence and accuracy.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method for a multi-segment, individually rotatable continuous robot, characterized in that, include: S1: Establish the forward kinematics model of the continuum robot; The continuum robot comprises two flexible segments and an end effector. The first flexible segment is a rotary segment, used to achieve large-angle rotation, keeping the second flexible segment and the end effector facing the patient. The second flexible segment is a motion segment, used to allow the end effector to directly contact each lesion point based on the positioning of the rotary segment, so as to perform vNOTES surgery. Each segment is equipped with a drive wire. The bending motion of each segment is converted into linear motion of the drive wire by a motor-driven gear and a screw transmission mechanism. The rotational motion of each segment is directly driven by the motor-driven gear through gear meshing. The establishment of the forward kinematics model of the continuum robot involves constructing coordinate systems O0X0Y0Z0, O1X1Y1Z1, O2X2Y2Z2, O3X3Y3Z3, O4X4Y4Z4, and O5X5Y5Z5 for the reference position, the rotary segment, the rigid connection between the rotary segment and the motion segment, the motion segment, the rigid connection between the motion segment and the end effector, and the end effector, respectively. θ1 represents the bending angle of the turning segment; θ1 represents the rotation angle of the rotating segment about Z0 of the coordinate system O0X0Y0Z0; θ2 represents the bending angle of the moving segment. This represents the rotation angle of the moving segment around Z2 of the coordinate system O2X2Y2Z2; This represents the rotation angle of the end effector about Z4 of the coordinate system O4X4Y4Z4; S2: Solve for configuration parameters based on the end-effector pose of the continuum robot; S3: Solve for the change in length of the driving wire in each segment; Step S3 involves determining the change in length of the driving wire in each segment. Let d1 be the offset of the driving wire from the center of the segment's cross-section in the rotating segment; then, in the rotating segment, the change in driving wire length Δl... 10 =d1θ1; In the motion segment, let d2 be the offset of the driving wire from the center of the segment's cross-section, and let Δl be the change in the length of the driving wire. 20 =d2θ2; S4: Perform parameter compensation for structural coupling; Step S4, which involves parameter compensation for structural coupling, addresses the issue that a portion of the moving segment's length lies within the rotating segment. When the rotating segment is in a bent state, the length of the driving wire in that portion of the moving segment changes accordingly. This type of coupling needs to be decoupled, and the change is compensated for in the length of the driving wire in the moving segment. The change in the length of the driving wire in the moving segment after parameter compensation for structural coupling is: S5: Perform parameter compensation for drive coupling; Step S5, which involves parameter compensation for the drive coupling, aims to eliminate the bending of the corresponding segment caused by the linear motion tension of the drive wire. When the corresponding rotating gear rotates clockwise while the corresponding bent gear remains stationary, for the screw drive mechanism, this is equivalent to the corresponding bent gear undergoing counterclockwise rotational drive coupling. To decouple the bending gear, the bent gear moves simultaneously with the corresponding rotating gear. The parameter compensation for this is as follows: Where k is the transmission ratio of the lead screw drive mechanism; S6: Obtain the target position of the driving variable gear.

2. The control method for a multi-segment independently rotatable continuous robot according to claim 1, characterized in that, make For the (i+1)th coordinate system O i+1 X i+1 Y i+1 Z i+1 Relative to the i-th coordinate system O i X i Y i Z i The transformation matrix, It describes the change in the reference position of the rotating segment relative to the continuous robot; This describes the transformation matrix of the rigid connection between the rotating segment and the moving segment relative to the rotating segment. This describes the transformation matrix of the moving segment relative to the rotating segment and the rigid connection between the moving segment and the rotating segment. This describes the transformation matrix between the rigid connection between the moving segment and the end effector and the moving segment. The transformation matrix described is the transformation matrix of the end effector relative to the rigid connection between the motion segment and the end effector; then the pose T of the end effector relative to the reference position of the continuum robot is expressed as: In the above expression, s represents the sine function sin, c represents the cosine function cos, l1 is the length of the rotary segment; lu1 is the length of the rigid connection between the rotary segment and the motion segment; l2 is the length of the motion segment; lu2 is the length of the rigid connection between the motion segment and the end effector; and l3 is the length of the end effector.

3. The control method for a multi-segment independently rotatable continuous robot according to claim 2, characterized in that, Step S2, which involves solving for the configuration parameters based on the end-effector pose of the continuum robot, assumes that parameters l1, l2, l3, lu1, and lu2 are known; and that parameters θ1, θ2, ... and For the unknown configuration parameters to be solved; the pose T of the end effector relative to the reference position of the continuum robot is rewritten as the following homogeneous transformation matrix: Where p x p y and p z This indicates the position of the origin of coordinate system O5X5Y5Z5 within coordinate system O0X0Y0Z0; n x n y and n z a represents the unit vector of the X5 axis of coordinate system O5X5Y5Z5 in coordinate system O0X0Y0Z0; x a y and a z b represents the unit vector of the Y5 axis of coordinate system O5X5Y5Z5 in coordinate system O0X0Y0Z0; x b y and b z The Z5 axis of coordinate system O5X5Y5Z5 represents the unit vector in coordinate system O0X0Y0Z0; By finding the inverse of the alignment transformation matrix, the configuration parameters θ1 and θ2 of the end effector pose of the continuum robot can be obtained. and 4. The control method for a multi-segment independently rotatable continuous robot according to claim 1, characterized in that, Step S6 describes obtaining the target position of the driving variable gear. For the rotary segment, the rotation of the corresponding gear directly causes the segment to rotate; for the moving segment, when the rotary gear moves clockwise while the moving gear is stationary, it is equivalent to the moving gear moving counterclockwise relative to the rotary segment. After compensating for the coupling effects of the bending and rotational motions one by one, a set of driving variables is obtained: The aforementioned driving variables correspond to the target positions of a set of gears.

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