Large-deflection deformation flexible shaft hole assembling method and device based on tactile perception, storage equipment and program product

Abstract

The invention discloses a large-deflection deformation flexible shaft hole assembly method and device based on tactile perception, storage equipment and a program product, and belongs to the technical field of robot assembly. The problem that an existing assembling method does not consider the influence of non-linear large-deflection deformation of the flexible shaft on the assembling precision of the shaft hole is solved. Based on pressure distribution data fed back by the tactile sensor, the deformation condition of the shaft can be estimated and adjusted, the flexible shaft workpiece makes effective contact with the rigid plane where the target hole is located, whether the shaft passes through the hole or not is monitored in real time in the blind hole searching process, and after the hole is searched, the mechanical arm is controlled to automatically align the shaft hole, so that the hole searching efficiency is improved. And the shaft insertion action is completed. The device is mainly used for shaft hole assembly of the large-deflection deformation flexible shaft workpiece.

Description

Technical Field

[0001] The invention belongs to the technical field of robot assembly, and in particular relates to a shaft hole assembly method for a flexible shaft with large deflection deformation based on tactile perception. Background Art

[0002] With the improvement of robot control theory and the development of various skill learning methods, robots have been able to operate rigid objects autonomously, but they still have difficulty handling non-rigid flexible materials. In the operation of flexible objects, due to their strong nonlinearity, strong deformation and other characteristics, coupled with high precision, unstructured environment and other task requirements, there are huge challenges in sensing, modeling, planning and controlling flexible objects. Shaft-hole assembly is a typical task in robot assembly technology. Conventional rigid shaft-hole assembly methods generally use robot force feedback control, which is difficult to directly apply to flexible shafts with large deflection deformation characteristics. Shaft-hole assembly technology for flexible shafts is generally based on visual methods, such as using depth and color images, and model-based tracking to achieve real-time perception of flexible objects, estimate the elastic modulus and posture of the grasped object, and predict deformation. However, this method has not been verified under complex force interactions. Based on visual servoing, the deformation of the end of the deformable slender shaft is modeled, and the differential motion relationship between the image features and the robot joints is derived. When the image features converge to the expected features, the shaft-hole alignment is completed. The vision-based method is limited by factors such as image quality and occlusion. However, this method is applied to specific tasks and is not easy to generalize. Subsequently, a model-free robust adaptive control (MFRAC) strategy was proposed to control a robot with unknown dynamics to operate a flexible rubber object with unknown elasticity. They used a Gaussian mixture model (GMM) based on a combined distribution similarity measure (DSM) to model the contact state of the rubber rod. However, the flexible rubber rod they used has a small aspect ratio, that is, it is not easy to undergo large deflection deformation, and cannot be transferred to a more general flexible slender shaft.

[0003] With the advancement of sensing technology, tactile sensors are widely used in robot operation tasks, such as object attribute recognition, grasping operations, human-computer interaction, etc. Robot tactile sensing technology generally includes resistive tactile sensors, capacitive tactile sensors, visual tactile sensors, etc., which have one-dimensional or multi-dimensional force sensing capabilities and provide robots with the ability to perceive the local touch of the end effector.

[0004] There are many precedents of successfully applying tactile sensors to assembly tasks. Robots with tactile perception can estimate the posture of the clamped object through touch, thereby implementing accurate assembly without relying on vision and additional force sensors. However, the posture of the flexible shaft is more difficult to estimate. To complete the shaft-hole assembly task, existing tactile perception robots do not consider the impact of the flexible shaft's nonlinear large deflection on the shaft-hole assembly accuracy, so it is necessary to design a method that considers the nonlinear large deflection deformation of the flexible shaft. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that the existing assembly method does not consider the influence of the nonlinear large deflection deformation of the flexible shaft on the shaft hole assembly accuracy. The present invention provides a large deflection deformation flexible shaft hole assembly method, device, storage device and program product based on tactile perception.

[0006] A flexible shaft hole assembly method with large deflection deformation based on tactile perception, the method comprising:

[0007] S1, preparation stage: after installing the thin film pressure tactile sensor array on the end gripper of the robot arm, control the end gripper of the robot arm to grip the flexible shaft workpiece and keep the flexible shaft workpiece perpendicular to the rigid plane where the target hole is located, and prepare for assembly operation; wherein the thin film pressure tactile sensor array is used to sense the distribution data of the gripping force;

[0008] S2, operation close to the target hole: the tactile sensing deformation control algorithm controls the flexible shaft workpiece and the rigid plane to form effective contact according to the sensed clamping force distribution data; the effective contact is the height z of the flexible shaft workpiece after deformation. est In the effective deformation range [z min , z max ] and keep the flexible shaft workpiece in contact with the upper surface of the rigid plane; the height z of the flexible shaft workpiece after deformation est is the vertical height between the clamping jaw and the bottom end of the flexible shaft workpiece; z min The minimum height value to prevent the shaft hole from getting stuck, z max is the maximum height value of the axis and the rigid surface to produce stable contact, and z max Smaller than the length of the flexible shaft workpiece in the free state;

[0009] S3, target hole search operation: control the robot arm to move in the horizontal direction according to the set hole search trajectory, so that the bottom end of the flexible shaft workpiece moves back and forth linearly along the preset path to slide the rigid plane, and search for the target hole according to the change in the clamping force distribution data sensed at the current moment and the previous moment. When it is determined that the flexible shaft workpiece passes through the target hole at the current moment, the robot arm stops moving;

[0010] S4, jack operation: according to the deviation between the current perceived clamping force distribution data and the perceived clamping force distribution data in the initial preparation stage, the relative position error between the axis and the hole is calculated, and the control amount of the horizontal movement direction and movement distance of the robot arm is determined according to the relative position error between the axis and the hole to control the movement of the robot arm to achieve the alignment of the flexible axis workpiece with the target hole, and then control the robot arm to move downward to a given depth h step , complete the jack.

[0011] Preferably, in step S2, the tactile sensing deformation control algorithm controls the flexible shaft workpiece to form effective contact with the rigid plane according to the sensed clamping force distribution data, and the implementation method includes the following steps:

[0012] S21, controlling the flexible shaft workpiece to move toward the rigid plane according to the spatial position of the rigid plane, and the bottom end of the flexible shaft workpiece contacts the upper surface of the rigid plane;

[0013] S22, the pre-trained CNN network predicts the height z of the flexible shaft workpiece after deformation based on the numerical matrix M formed by the clamping force distribution data sensed by the thin film pressure tactile sensor array est ;

[0014] S23, determine whether z is satisfied est In the effective deformation range [z min , z max ], if the result is yes, it is determined that the flexible shaft workpiece forms effective contact with the rigid plane, and step S25 is executed; if the result is no, step S24 is executed;

[0015] S24, controlling the robot arm to move upward in the vertical direction, and returning to step S22;

[0016] S25, maintain the height z of the flexible shaft workpiece after deformation est Constant.

[0017] Preferably, in step S3, the implementation method of searching for the target hole according to the change in the clamping force distribution data sensed at the current moment and the previous moment is:

[0018] When the variation between the numerical matrix formed by the clamping force distribution data sensed by the thin film pressure tactile sensor array at the current moment and the previous moment is greater than the preset threshold, it is determined that the flexible shaft workpiece passes through the target hole at the current moment and the target hole search is completed.

[0019] Preferably, in step S4, the calculation of the relative position error e between the shaft and the hole is implemented as follows:

[0020] e=mean(M t -M Target );

[0021] Mt is the numerical matrix of the clamping force distribution data sensed by the pressure tactile sensor array at the current time t, M Target is the numerical matrix of the clamping force distribution data sensed by the pressure tactile sensor array when the flexible shaft workpiece is not subjected to external forces except the clamping force, and mean() is the column-wise average of the vector.

[0022] Preferably, in step S4, the implementation method of determining the control amount of the horizontal movement direction and movement distance of the robot arm according to the relative position error between the shaft and the hole includes:

[0023] When the relative position error between the axis and the hole is greater than the preset relative position tolerance error, the PID control generates a control quantity for controlling the horizontal movement direction and movement distance of the robot arm according to the relative position error between the axis and the hole.

[0024] Preferably, the gripper is implemented as an adaptive two-finger gripper.

[0025] Preferably, a thin film pressure tactile sensor array is mounted on one or both sides of the adaptive two-finger gripper.

[0026] A flexible shaft hole assembly device based on tactile perception includes a storage device, a processor, and a computer program stored in the storage device and executable on the processor. The processor executes the computer program to implement the flexible shaft hole assembly method with large deflection deformation based on tactile perception.

[0027] A computer-readable storage device stores a computer program, and when the computer program is executed, the flexible shaft-hole assembly method with tactile perception is implemented.

[0028] A computer program product comprises a computer program, which, when executed by a processor, implements the tactile-perceived flexible shaft-hole assembly method as described above.

[0029] The beneficial effects brought by the present invention are:

[0030] In view of the fact that a flexible shaft may experience large deflection deformation when interacting with the environment, the present invention innovatively applies tactile sensing technology and designs effective solutions for each major process of shaft-hole assembly.

[0031] First of all, in order to control the deformation of the flexible shaft during operation, traditional vision technology requires complex image processing algorithms and cannot cope with operating requirements under harsh working conditions such as obstacle obstruction and insufficient light. A single wrist force sensor cannot accurately sense the deformation of the flexible shaft. The tactile technology used in the present invention can accurately and efficiently sense the deformation of the flexible shaft to facilitate control.

[0032] Secondly, the present invention does not need to estimate the specific position of the end of the flexible shaft workpiece, and can quickly enable the shaft to find the hole according to the tactile response.

[0033] Finally, the present invention does not require additional force control and relies on tactile feedback to align the hole axis and complete the insertion.

[0034] Compared with the prior art, the present invention only uses single-dimensional tactile perception, enabling the robot to automatically and accurately complete the shaft hole assembly task of the flexible workpiece. The cost of the visual and force sensors used in the prior art is generally high, while the thin film tactile sensor used in the present invention is low in cost and has a very high cost-effectiveness in completing the same task, greatly reducing the cost and complexity of the assembly system.

[0035] The present invention establishes a shaft hole assembly strategy for a flexible shaft workpiece with large deflection deformation based on tactile perception. The application of the present invention can realize a smart and precise assembly operation of the flexible shaft workpiece, which has a certain inspiration and optimization effect on the industrial assembly of flexible parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of the method for assembling a flexible shaft hole with large deflection deformation based on tactile perception according to the present invention;

[0037] Figure 2 Flow chart for controlling the flexible shaft workpiece to form effective contact with the rigid plane;

[0038] Figure 3 Schematic diagram of hole searching process;

[0039] Figure 4 A schematic diagram of the interaction between a flexible shaft workpiece and a rigid plane is given; among them,

[0040] Figure 4 a is a schematic diagram of the state when the flexible shaft workpiece and the rigid plane produce contact deformation. Figure 4 b is a schematic diagram of the state when the flexible shaft workpiece meets the target hole on the rigid plane. Figure 4 c is a schematic diagram of the state when the shaft hole is blocked. Figure 4 d is a schematic diagram of the state when the shaft hole is blocked and the large deformation is caused by inserting the hole downward;

[0041] Figure 5 This is a graph showing the measurement value change trend of a sensing unit in the thin film pressure tactile sensor array during the shaft hole assembly process. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0044] The present invention designs a method for guiding a robot to perform shaft hole assembly operations by using the measurement value feedback of a tactile sensor, which can realize deformation control of a flexible shaft workpiece, blind hole search and plug-in. The present invention installs an array-type thin film pressure tactile sensor in the clamp as a tactile sensing device, which can detect the distribution data of the normal clamping force. At the same time, the robot is not equipped with any additional six-dimensional force sensor or visual sensor for additional force feedback or visual feedback. The object to be operated is a slender shaft made of soft material as a flexible shaft workpiece, which can achieve elastic deformation with large deflection under the action of external force.

[0045] Based on the pressure distribution data fed back by the tactile sensor, the deformation of the shaft can be estimated and adjusted to make the flexible shaft workpiece effectively contact the rigid plane where the target hole is located. During the blind hole search process, it is monitored in real time whether the shaft passes through the hole. After finding the hole, the control robot automatically aligns the shaft hole to complete the shaft insertion. The specific implementation methods provided are as follows:

[0046] Specific implementation method 1, refer to 1 to explain this implementation method, the large deflection deformation flexible shaft hole assembly method based on tactile perception described in this implementation method includes:

[0047] S1, preparation stage: after installing the thin film pressure tactile sensor array on the end gripper of the robot arm, control the end gripper of the robot arm to grip the flexible shaft workpiece and keep the flexible shaft workpiece perpendicular to the rigid plane where the target hole is located, and prepare for assembly operation; wherein the thin film pressure tactile sensor array is used to sense the distribution data of the gripping force;

[0048] S2, operation close to the target hole: the tactile sensing deformation control algorithm controls the flexible shaft workpiece and the rigid plane to form effective contact according to the sensed clamping force distribution data; the effective contact is the height z of the flexible shaft workpiece after deformation. est In the effective deformation range [z min , z max ] and keep the flexible shaft workpiece in contact with the upper surface of the rigid plane; the height z of the flexible shaft workpiece after deformation est is the vertical height between the clamping jaw and the bottom end of the flexible shaft workpiece; zmin The minimum height value to prevent the shaft hole from getting stuck, z max is the maximum height value of the axis and the rigid surface to produce stable contact, and z max Smaller than the length of the flexible shaft workpiece in the free state;

[0049] S3, search target hole operation: control the robot arm to move in the horizontal direction according to the set hole search trajectory, so that the bottom of the flexible shaft workpiece moves back and forth in a linear motion along the preset path to slide the rigid plane, and search for the target hole according to the change in the clamping force distribution data sensed at the current moment and the previous moment. When it is determined that the flexible shaft workpiece passes through the target hole at the current moment, the robot arm stops moving. For details, see Figure 3 ;

[0050] S4, jack operation: according to the deviation between the current perceived clamping force distribution data and the perceived clamping force distribution data in the initial preparation stage, the relative position error between the axis and the hole is calculated, and the control amount of the horizontal movement direction and movement distance of the robot arm is determined according to the relative position error between the axis and the hole to control the movement of the robot arm to achieve the alignment of the flexible axis workpiece with the target hole, and then control the robot arm to move downward to a given depth h step , complete the jack.

[0051] This specific implementation adopts a simple and low-cost thin-film pressure tactile sensor array, so that the robot arm can perform tactile perception during the operation process. The pressure distribution felt by the tactile unit can reflect the large deflection deformation of the flexible shaft. In the process of approaching the target hole, the deformation control algorithm based on tactile perception is used to adjust the deformation degree of the flexible shaft, and in the process of searching for the target hole, the change of the clamping force distribution is sensed by tactile perception to detect the encounter of the hole and the shaft. Finally, tactile feedback is used to guide the robot arm to eliminate the relative position error of the shaft and the hole to complete the insertion. Compared with the prior art, the present invention adopts a single-dimensional tactile feedback, which is low in cost and high in efficiency. It not only reduces the complexity of the assembly system, but also ensures that the robot arm automatically controls the deformation of the shaft, accurately finds holes and inserts holes, and is easy to use.

[0052] The implementation basis of shaft-hole assembly is to establish effective force contact between the shaft and the plane. Traditional rigid shaft-hole assembly often uses force-position hybrid control or impedance control, which are difficult to directly apply to shafts with large inherent compliance. For flexible shaft workpieces, deformation control is the key to controlling the interaction between the shaft and the environment. Due to the uncertainty of the rigid plane where the target hole is located in the z direction, it is necessary to determine the contact between the shaft and the plane and the hole by detecting the deformation of the shaft. Figure 4As shown in the figure, when the shaft is bent from a free state, it means that the shaft is in contact with the plane, that is, the plane is found. According to the deformation theory of flexible shaft workpieces, greater deformation will cause more obvious changes in sensor values ​​and facilitate detection, but excessive deformation may sometimes cause some unexpected situations, such as shaft hole jamming. Figure 4 c. The horizontal movement of the clamp cannot make the shaft fall into the hole. When the deformation caused by the interaction between the shaft and the plane is too large, the shaft will get stuck when passing over the hole. In this case, no matter how the horizontal position of the shaft is adjusted, the error of the shaft-hole posture cannot be eliminated. If the shaft is controlled to be inserted downward at this time, not only will the shaft fail to fall into the hole, but it will also produce greater deformation. Therefore, it is necessary to design a reasonable deformation control strategy to make the shaft and the plane have effective contact while avoiding excessive deformation.

[0053] Therefore, it is necessary to limit the effective deformation range of the flexible shaft workpiece [z min , z max ], so that the height of the flexible shaft workpiece after deformation is in the effective deformation range [z min , z max ] to achieve accurate shaft-hole assembly, see Figure 2 , specifically give

[0054] In step S2, the tactile sensing deformation control algorithm controls the flexible shaft workpiece and the rigid plane to form effective contact according to the sensed clamping force distribution data, and the implementation method includes the following steps:

[0055] S21, controlling the flexible shaft workpiece to move toward the rigid plane according to the spatial position of the rigid plane, and the bottom end of the flexible shaft workpiece contacts the upper surface of the rigid plane;

[0056] S22, the pre-trained CNN network predicts the height z of the flexible shaft workpiece after deformation based on the numerical matrix M formed by the clamping force distribution data sensed by the thin film pressure tactile sensor array est ;

[0057] S23, determine whether z is satisfied est In the effective deformation range [z min , z max ], if the result is yes, it is determined that the flexible shaft workpiece forms effective contact with the rigid plane, and step S25 is executed; if the result is no, step S24 is executed;

[0058] S24, controlling the robot arm to move upward in the vertical direction, and returning to step S22;

[0059] S25, maintain the height z of the flexible shaft workpiece after deformation est Constant.

[0060] In this preferred embodiment, based on the tactile pressure distribution characteristics caused by large deflection of the flexible shaft, the necessary conditions for the flexible shaft to contact the plane are considered, and the situation that the flexible shaft will be blocked by the shaft hole and cause assembly failure when the deformation is too large is considered. The deformation range for controlling the flexible shaft workpiece to form effective contact with the rigid plane is given, and a CNN network is designed to establish the relationship between the deformation of the flexible shaft and the height z. est The mapping between them enables the robot arm to be adjusted in the vertical direction to change the deformation of the shaft, thereby making the shaft within the effective deformation range. It is precisely because the deformation of the flexible shaft is effectively controlled that the shaft hole jamming is avoided.

[0061] Specifically, in step S3, the implementation method of searching for the target hole according to the change in the clamping force distribution data sensed at the current moment and the previous moment is:

[0062] When the variation between the numerical matrix formed by the clamping force distribution data sensed by the thin film pressure tactile sensor array at the current moment and the previous moment is greater than the preset threshold, it is determined that the flexible shaft workpiece passes through the target hole at the current moment and the target hole search is completed.

[0063] Furthermore, in step S4, the relative position error e between the shaft and the hole is calculated as follows:

[0064] e=mean(M t -M Target );

[0065] M t is the numerical matrix of the clamping force distribution data sensed by the pressure tactile sensor array at the current time t, M Target is the numerical matrix of the clamping force distribution data sensed by the pressure tactile sensor array when the flexible shaft workpiece is not subjected to external forces except the clamping force, and mean() is the column-wise average of the vector.

[0066] Further, in step S4, the implementation method of determining the control amount of the horizontal movement direction and movement distance of the robot arm according to the relative position error between the shaft and the hole includes:

[0067] When the relative position error between the axis and the hole is greater than the preset relative position tolerance error, the PID control generates a control quantity for controlling the horizontal movement direction and movement distance of the robot arm according to the relative position error between the axis and the hole.

[0068] In this preferred embodiment, PID control can be implemented through existing technology to generate control quantities for controlling the horizontal movement direction and movement distance of the robot arm according to the relative position error between the shaft and the hole, and the advantage of this setting method for the jacking operation is that there is no need to consider the precise position of the end of the flexible shaft workpiece and the hole in the robot coordinate system. The tactile pressure distribution characteristics of the flexible shaft that do not undergo large deflection deformation when not subjected to any force except the clamping force are used as the control target, so that the robot can complete the shaft-hole alignment and jacking by only adjusting the relative position of the flexible shaft and the hole without knowing the precise position of the hole, thereby greatly reducing the complexity of the task.

[0069] Furthermore, the clamp is implemented by an adaptive two-finger clamp. Specifically, the installation position of the thin film pressure tactile sensor array can be on one side or both sides of the adaptive two-finger clamp.

[0070] Specific embodiment 2: The flexible shaft hole assembly device based on tactile perception described in this embodiment includes a storage device, a processor, and a computer program stored in the storage device and executable on the processor. The processor executes the computer program to implement the large deflection deformation flexible shaft hole assembly method based on tactile perception as described in specific embodiment 1.

[0071] Specific implementation method three: This implementation method describes a computer-readable storage device, wherein the storage device stores a computer program, and when the computer program is executed, the tactilely-perceived flexible shaft hole assembly method described in specific implementation method one is implemented.

[0072] Specific implementation method 4: A computer program product described in this implementation method includes a computer program, and when the computer program is executed by a processor, the tactile perception flexible shaft hole assembly method described in specific implementation method 1 is implemented.

[0073] Verification test:

[0074] The effectiveness of the present invention is demonstrated by the following verification test. Specifically, the present invention method has been verified by the test, without using the optical camera and six-dimensional force sensor commonly used in the traditional assembly method, only the array-type thin film pressure distribution tactile sensor is equipped. During the test, the pressure change of a certain contact point in the tactile sensor array is as follows: Figure 5 As shown, Figure 5 The horizontal axis is the sampling point, and the vertical axis is the sensitivity (dimensionless), and its display range is 0-4095;

[0075] Figure 5It is reflected in that, in the stage close to the target hole, the flexible shaft and the plane have not yet contacted, and the pressure signal of the tactile unit is basically 0. When the flexible shaft establishes effective contact with the plane, the pressure signal of the tactile unit rises to a larger value. After estimating the deformation amount and confirming that the shaft is in the effective deformation range, the search begins. Since the deformation remains constant, the tactile signal also remains constant at this time. When the shaft passes over the hole, the pressure signal of the contact point shows obvious jitter. In the process of eliminating the relative position error of the shaft and hole, the pressure value of the tactile unit decreases once each time the robot arm is adjusted, until it finally approaches 0, indicating that the shaft and hole are aligned. At this time, the robot arm is controlled to insert the hole downward to complete the operation. Experimental verification shows that the tactile information used by the present invention can effectively and regularly guide the robot arm to complete the shaft hole assembly task of a flexible shaft with large deflection deformation.

[0076] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A flexible shaft hole assembly method with large deflection deformation based on tactile perception, characterized in that: Methods include: S1, preparation stage: after installing the thin film pressure tactile sensor array on the end gripper of the robot arm, control the end gripper of the robot arm to grip the flexible shaft workpiece and keep the flexible shaft workpiece perpendicular to the rigid plane where the target hole is located, and prepare for assembly operation; wherein the thin film pressure tactile sensor array is used to sense the distribution data of the gripping force; S2, operation close to the target hole: the tactile sensing deformation control algorithm controls the flexible shaft workpiece and the rigid plane to form effective contact according to the sensed clamping force distribution data; the effective contact is the height z of the flexible shaft workpiece after deformation. est In the effective deformation range [z min , z max ] and keep the flexible shaft workpiece in contact with the upper surface of the rigid plane; the height z of the flexible shaft workpiece after deformation est is the vertical height between the clamping jaw and the bottom end of the flexible shaft workpiece; z min The minimum height value to prevent the shaft hole from getting stuck, z max is the maximum height value of the axis and the rigid surface to produce stable contact, and z max Smaller than the length of the flexible shaft workpiece in the free state; S3, target hole search operation: control the robot arm to move in the horizontal direction according to the set hole search trajectory, so that the bottom end of the flexible shaft workpiece moves back and forth linearly along the preset path to slide the rigid plane, and search for the target hole according to the change in the clamping force distribution data sensed at the current moment and the previous moment. When it is determined that the flexible shaft workpiece passes through the target hole at the current moment, the robot arm stops moving; S4, jack operation: according to the deviation between the current perceived clamping force distribution data and the perceived clamping force distribution data in the initial preparation stage, the relative position error between the axis and the hole is calculated, and the control amount of the horizontal movement direction and movement distance of the robot arm is determined according to the relative position error between the axis and the hole to control the movement of the robot arm to achieve the alignment of the flexible axis workpiece with the target hole, and then control the robot arm to move downward to a given depth h step , complete the jack.

2. The method for assembling a flexible shaft hole with large deflection deformation based on tactile perception according to claim 1 is characterized in that: In step S2, the tactile sensing deformation control algorithm controls the flexible shaft workpiece and the rigid plane to form effective contact according to the sensed clamping force distribution data, and the implementation method includes the following steps: S21, controlling the flexible shaft workpiece to move toward the rigid plane according to the spatial position of the rigid plane, and the bottom end of the flexible shaft workpiece contacts the upper surface of the rigid plane; S22, the pre-trained CNN network predicts the height z of the flexible shaft workpiece after deformation based on the numerical matrix M formed by the clamping force distribution data sensed by the thin film pressure tactile sensor array est ; S23, determine whether z is satisfied est In the effective deformation range [z min , z max ], if the result is yes, it is determined that the flexible shaft workpiece forms effective contact with the rigid plane, and step S25 is executed; if the result is no, step S24 is executed; S24, controlling the robot arm to move upward in the vertical direction, and returning to step S22; S25, maintain the height z of the flexible shaft workpiece after deformation est Constant.

3. The method for assembling a flexible shaft hole with large deflection deformation based on tactile perception according to claim 1 is characterized in that: In step S3, the implementation method of searching for the target hole according to the change in the clamping force distribution data sensed at the current moment and the previous moment is: When the variation between the numerical matrix formed by the clamping force distribution data sensed by the thin film pressure tactile sensor array at the current moment and the previous moment is greater than the preset threshold, it is determined that the flexible shaft workpiece passes through the target hole at the current moment and the target hole search is completed.

4. The method for assembling a flexible shaft hole with large deflection deformation based on tactile perception according to claim 1 is characterized in that: In step S4, the relative position error e between the shaft and the hole is calculated as follows: e=mean(M t -M Target ); M t is the numerical matrix of the clamping force distribution data sensed by the pressure tactile sensor array at the current time t, M Target is the numerical matrix of the clamping force distribution data sensed by the pressure tactile sensor array when the flexible shaft workpiece is not subjected to external forces except the clamping force, and mean() is the column-wise average of the vector.

5. The method for assembling a flexible shaft hole with large deflection deformation based on tactile perception according to claim 1 is characterized in that: In step S4, the implementation method of determining the control amount of the horizontal movement direction and movement distance of the robot arm according to the relative position error between the shaft and the hole includes: When the relative position error between the axis and the hole is greater than the preset relative position tolerance error, the PID control generates a control quantity for controlling the horizontal movement direction and movement distance of the robot arm according to the relative position error between the axis and the hole.

6. The method for assembling a flexible shaft hole with large deflection deformation based on tactile perception according to claim 1 is characterized in that: The gripper is realized with an adaptive two-finger gripper.

7. The method for assembling a flexible shaft hole with large deflection deformation based on tactile perception according to claim 1 is characterized in that: An array of thin-film pressure tactile sensors is mounted on one or both sides of the adaptive two-finger gripper.

8. A flexible shaft-hole assembly device based on tactile perception, comprising a storage device, a processor, and a computer program stored in the storage device and executable on the processor, characterized in that: The processor executes a computer program to implement the large deflection deformation flexible shaft hole assembly method based on tactile perception as described in any one of claims 1 to 7.

9. A computer-readable storage device, characterized in that: The storage device stores a computer program, wherein the computer program, when executed, implements the tactilely perceived flexible shaft hole assembly method as claimed in any one of claims 1 to 7.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the tactilely-perceived flexible shaft-hole assembly method according to claims 1 to 7 is implemented.

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