Variable length continuous robot and capture method

Abstract

The application belongs to the field of robots, in particular to a variable-length continuous robot and a capturing method. The robot comprises a control box, a base joint, a flexible catcher and a length extender. The flexible catcher realizes envelope mode capturing of a target by controlling the length of a driving line. The length extender is connected with the flexible catcher, and pushes out or retracts the flexible catcher to realize increase or decrease of the effective capturing length. The base joint is located between the length extender and the control box, and realizes adjustment of the flexible catcher to targets with different direction angles in a two-dimensional plane. A control structure of the driving line and a controller are arranged in the control box, and the control module is used for issuing instructions to control the driving line, the length extender and the base joint. The application expands the range of captured targets for capturing targets with different sizes and shapes, and has the advantages of simple control and wide application.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of robots, and particularly relates to a variable-length continuous robot and a capturing method. BACKGROUND

[0002] The existing variable-length continuous robots mainly have a tension structure, a paper folding structure and a concentric tube structure. The tension structure realizes the change and bending of the length of the robot through the movement of multiple unit connecting rods, but the structure is complex and difficult to be applied in practice. The paper folding structure realizes the stretching, bending and twisting of the robot by using the unfoldability of the structure, but the continuous robot based on the paper folding structure is usually driven by fluid, and the maintenance of the driving device is difficult. In addition, the materials of the above two kinds of variable-length continuous robots are mainly rigid rods, which are easy to cause damage to the targets with light and soft texture. SUMMARY

[0003] The application aims to provide a variable-length continuous robot and a capturing method, and solve the problems that the existing variable-length continuous robots are easy to cause damage to the targets with light and soft texture and difficult to control.

[0004] The application provides a variable-length continuous robot. The robot is driven by a motor rope to complete the bending movement of the robot and realize the enveloping capture of the target. The robot is provided with rigid and flexible double tubes to realize the change of the length of the robot and capture the targets with different sizes and shapes, expand the range of the captured targets, and has the advantages of simple control and wide application, and can be used for internal fault detection of a spacecraft, disaster environment detection, space debris cleaning and the like, and is mainly applied in the fields of rescue, medical treatment, aerospace and the like.

[0005] The application is achieved in the following manner. A variable-length continuous robot comprises:

[0006] a control box, a base joint, a flexible catcher and a length extender;

[0007] The flexible catcher realizes the enveloping capture of the target by controlling the length of the driving line.

[0008] The length extender is connected with the flexible catcher to push out or retract the flexible catcher and realize the increase and decrease of the effective capture length.

[0009] The base joint is located between the length extender and the control box to realize the adjustment of the flexible catcher to the targets in different directions in a two-dimensional plane.

[0010] The control box is internally provided with a control structure of a driving line and a controller, and the control module is used to issue instructions to control the driving line, the length extender and the base joint.

[0011] Further, the flexible gripper comprises a plurality of joint discs fixed on two flexible skeletons, the cross section of the joint disc is circular, and three penetrating holes are distributed at equal angles of the center of the joint disc, and the three penetrating holes are used to penetrate the two flexible skeletons and a driving line respectively.

[0012] Further, the joint discs have a spacing, the flexible skeleton is made of super-elastic nickel-titanium alloy, and the driving line is made of nylon material.

[0013] Further, the length extender comprises a hard support sleeve and an extensible rod connected with the hard support sleeve, the extensible rod is fixed with the flexible gripper, a sensor mounting seat is installed at the distal end of the flexible gripper, and the effective capture length is from the starting point of the distal end of the hard sleeve to the terminal point of the exposed distal end of the flexible gripper, i.e. the sensor mounting seat.

[0014] Further, the base joint comprises a rotating joint and a motor C, and the rotating joint is controlled by the motor C according to the control module.

[0015] Further, a motor A is arranged in the control box, the motor A is connected with the driving line through a shaft coupling, a tension sensor is installed on the driving line, signals collected by the tension sensor are transmitted to a data acquisition card, and the information acquisition card is used to upload the signals to the control module and an upper computer.

[0016] A capture method of a variable-length continuous robot, according to the information of a target position and size known in advance, the motor B and the motor C are adjusted to make the elongation and the rotation angle reach the expected value, and then the flexible gripper forms a bending angle to capture the target in an envelope form, and the method specifically comprises the following steps:

[0017] Plane rotation, the base joint is rotated in a plane by the motor C, and the capture direction is determined according to the position of the target;

[0018] Length adjustment, after the plane rotation is completed, the effective capture length is determined according to the size and shape of the target, and then the elongation is adjusted by the motor B;

[0019] Winding capture, after the length is adjusted, the driving line starts to be tightened to capture the target, the deformation of the flexible gripper is realized by the motor A to control the driving line, and then the full envelope is formed to complete the capture of the target.

[0020] Further, the bending angle is predicted by using a RBF neural network, when the tension F(t) of the current driving line, the bending angle α(t), the elongation Δl(t) and the rotation angle θ(t) are known. Predicting the only bending angle at the next moment When the predicted angle satisfies , it is considered that the full envelope has been completed for the target.

[0021] Further, when the motor B and the motor C stop after reaching the specified state, the motor A is driven at an angle ω1, and according to the condition that the predicted angle satisfies , the motor A is driven at ω1 / 2 to grasp the target.

[0022] Further, in the process of forming a full envelope to grasp the target, the angular velocity of the motor A will capture a sudden change, i.e. the angular velocity is suddenly reduced, and according to the sudden change, it is judged whether the target has been grasped, otherwise the motor A continues to drive until the sudden change of the angular velocity is captured.

[0023] Compared with the prior art, the present application has the beneficial effects that:

[0024] The present application has strong adaptability, significant advantages in capturing non-cooperative targets in space, and independence of control.

[0025] 1: Strong self-adaptability.

[0026] Adaptability to targets of different shapes and sizes. First, according to the size of the target, the effective capture length of the length extender is adjusted, and then the flexible gripper is bent and deformed to capture the target. When the target is grasped, the gripper is used to grasp the target as a whole, and the final shape is determined by the shape and size of the target.

[0027] Adaptability to targets at different positions. A rotating joint is provided, which can adjust the direction angle in a two-dimensional plane under the premise of known target position, and as long as the relative position and size of the target are within the allowed range, the capture of targets at different positions can be realized, and the target can also be placed at different positions.

[0028] Adaptability to targets in different motion states. The gripper of the robot is flexible, and the "soft shell" protective cover can improve the robustness of the capture. For small amplitude motion targets, the capture task can be well completed in the case of slight collision of the target to the actuator, which presents the adaptability of the robot to the motion state of the object.

[0029] The realizability of the above operation in extreme environments. The length extender of the proposed robot is a rigid rod structure, and the flexible gripper is a joint disc-flexible skeleton structure. The power transmission between the joint discs is through the flexible skeleton and the nylon driving line, rather than liquid tendon or pneumatic muscle. As long as the appropriate materials are selected, it can be effectively applied in high vacuum, large temperature difference, strong radiation and other extreme environments for a long time, and has obvious advantages in reliability and service life.

[0030] 2: Significant advantage in capturing non-cooperative targets. When performing the capture task, the traditional robot may contact the irregularly moving target, which may cause it to roll and drift, so the robot with a manipulator for capture operation has the performance requirement of "soft capture". The multifunctional robot proposed in the application uses a new adaptive mode in the capture process, that is, the whole body of the robot envelops the captured target through the flexibility of the capture device. The contact force between the actuator and the target does not cause large impact and collision, and the soft capture can be achieved, which improves the capture efficiency and success rate.

[0031] 3: Independence of control. The existing continuous robot is generally based on multi-modal perception, planning and control, and requires multiple drivers to work together to finally achieve the capture of the target. Unlike the previous continuous robot, the robot proposed in the application uses three motors to independently control the plane rotation, length change and bending angle, which simplifies the requirements of the control system in the operation process of the robot. At the same time, the light rod structure of the length extender and the joint disc-flexible skeleton structure of the flexible capture device both reduce the weight burden of the robot and also reduce the requirement of motor torque. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The overall structure schematic diagram of the robot provided for the embodiment of the application is shown in the figure;

[0033] Figure 2 The structure schematic diagram of the flexible capture device of the robot provided for the embodiment of the application is shown in the figure;

[0034] Figure 3 The structure schematic diagram of the internal structure of the flexible capture device of the robot provided for the embodiment of the application is shown in the figure;

[0035] Figure 4 The structure schematic diagram of the control box of the robot provided for the embodiment of the application is shown in the figure;

[0036] Figure 5 The flowchart of the method provided for the embodiment of the application is shown in the figure. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the application clearer, the application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application.

[0038] The multifunctional continuous robot prototype proposed in the application is shown in the figure Figure 1As shown, the robot comprises a control box 1, a base joint 2, a flexible gripper 4 and a length extender 3; the flexible gripper 4 realizes enveloping mode grasping of the target by controlling the length of the driving wire; the length extender 3 is connected with the flexible gripper 4 to push out or retract the flexible gripper 4, thereby realizing increase or decrease of the effective grasping length; the base joint is located between the length extender and the control box to realize adjustment of the flexible gripper to targets in different direction angles in a two-dimensional plane; the control box is provided with a control structure of the driving wire and a controller, and the control module is used to issue instructions to control the driving wire, the length extender and the base joint.

[0039] Referring to Figure 2 In combination Figure 3 As shown, the flexible gripper is fixed on two flexible skeletons by 15 joint disks 48, the cross section of the joint disk is circular, and three penetrating holes are distributed at equal angles of center in the joint disk, the three penetrating holes are respectively used for penetrating two flexible skeletons and one driving wire 45, and an external "soft shell" protective sleeve 42 is arranged, the joint disk is made of a 3D printer and printing material, the thickness of the adjacent joint disks is 1.5 mm, and the spacing is 15 mm. The materials of the first flexible skeleton 43 and the second flexible skeleton 44 and the driving wire 45 are super-elastic nickel-titanium alloy and nylon respectively. The parameters of the gripper are shown in Table 1. The driving cable pulls the supporting skeleton to deform flexibly, and the bending action of the gripper is completed.

[0040] Table I Parameters of the flexible gripper

[0041]

[0042] In order to realize grasping of targets with different shapes and sizes, a variable length design is introduced. As shown in Figure 2 As shown, the length extender is composed of a hard support sleeve 47 and a telescopic rod 46, the flexible gripper is fixed with the telescopic rod 46, and the effective grasping length is from the starting point of the distal end of the hard sleeve to the terminal point of the exposed distal end of the flexible gripper, i.e. the sensor mounting seat 41. The variable length mechanism of the continuous robot is realized by changing the extension of the telescopic rod 46 to control the effective grasping length of the actuator. The telescopic rod 46 pushes out or retracts the grasping mechanism, thereby realizing increase or decrease of the effective grasping length. The telescopic rod 46 is driven by a DC motor B (the DC motor B is located at the top of the telescopic rod 46), and the DC motor B drives the telescopic rod at a constant speed, so as to control the change of the effective grasping length of the continuous actuator by only controlling the length of the forward and reverse rotation time of the driving motor of the telescopic rod 46, thereby realizing grasping of different targets. The extension Δl of the telescopic rod 46 ranges from 0 mm to 150 mm, so the effective grasping length of the robot ranges from 250 mm to 400 mm. Figure 2

[0043] ​In addition, a base joint is arranged between the length extender and the control box, the base joint comprises a rotating joint, and a motor C is arranged to control the rotating joint. The capture of a target with different direction angles within ±80° can be realized in a two-dimensional plane.

[0044] Referring to Figure 4 The control box comprises a driving module, a control module and a sensing module, as shown in Figure 4 The driving module comprises a motor A for driving the driving wire of the flexible manipulator, and the motor A 16 is arranged on the driving wire reel 11 through the shaft coupling 12 to provide driving force for the flexible manipulator to realize bending deformation. The tension sensor 15 and the data acquisition card 13 constitute the sensing module.

[0045] During the driving of the manipulator, the tension sensor 5 is used to measure the tension of the driving wire, and the measurement data is recorded and saved by the information acquisition card 3 and then uploaded to the upper computer. In order to control the driving of the driving rope, adjust the effective capture length of the manipulator and the direction angle of the motor C (the control module sends instructions to the root motor, i.e. the motor C to realize the change of the direction angle), a control module 17 is designed, which is composed of a main control board Arduino Uno and a motor driving board L298N.

[0046] The continuous robot control method comprises:

[0047] Under the independent driving of the three motors A, B and C, the motion cycle of a capture experiment is divided into three steps,

[0048] (1) Planar rotation. The base joint is rotated by the motor C, and the capture direction is determined according to the positions of the two targets.

[0049] (2) Length adjustment. After the steering motion is completed, the length extension of the effective capture length is determined according to the size and shape of the target, and the extension is adjusted by the motor B.

[0050] (3) Winding capture. After the appropriate length is adjusted, the driving wire starts to tighten to capture the target, and the deformation of the flexible manipulator is realized by the motor C to complete the capture of the target.

[0051] When the multifunctional continuous robot captures the target in an envelope mode, the extension and the rotation angle of the manipulator are adjusted to the desired values by the motors B and C according to the known information of the target position and size, and then the flexible manipulator captures the target in an envelope mode. The working process is shown in the following figure. The RBF neural network is used to predict the bending angle, and when the current tension F(t), bending angle α(t), extension Δl(t) and rotation angle The unique bending angle at the next moment can be predicted When the predicted angle satisfies At this time, it is considered that the continuous actuator has completed full envelopment to the target.

[0052] When the motor B and the motor C reach the specified state, the motor A is driven at an angle ω1, and the motor A is driven at ω1 / 2 according to the condition that the predicted angle satisfies the judgment.

[0053] In the process of forming full envelopment to the target, the angular velocity of the motor A will capture a sudden change, i.e., the angular velocity is suddenly reduced, and thus it is judged that the target has been gripped, otherwise the motor A continues to be driven until the sudden change of the angular velocity is captured, and the control flow chart is shown in the following Figure 5 .

[0054] The above only describes the preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A variable length continuous type robot, characterized in that: The robot includes: Control box, base joint, flexible gripper and length extender; The flexible catcher controls the length of the driving line to capture the target in an envelope manner; The length extender is connected to the flexible catcher to push out or retract the flexible catcher to increase or decrease the effective catch length; The base joint is located between the length extender and the control box to achieve the adjustment of the flexible catcher to different angular targets in a two-dimensional plane; A control module for the driving line is provided in the control box, and the control module is used to issue instructions to control the driving line, the length expander and the base joint; The flexible catcher includes a plurality of segmented discs fixed on two flexible skeletons. The segmented discs have a circular cross section and three insertion holes are distributed at equal central angles on the segmented discs. The three insertion holes are used to insert the two flexible skeletons and a driving wire respectively. The length expander includes a hard support sleeve and a telescopic rod connected to the hard support sleeve. The telescopic rod is fixed to the flexible catcher. A sensor mounting seat is installed at the far end of the flexible catcher. The far end of the hard sleeve is the starting point and the far end of the exposed flexible catcher, i.e., the sensor mounting seat, is the end point. This length is the effective capture length.

2. The variable length continuous type robot according to claim 1, characterized in that: There is a distance between the node disks, the flexible skeleton is made of super elastic nickel titanium alloy, and the driving wire is made of nylon.

3. The variable length continuous type robot according to claim 1, characterized in that: The base joint includes a rotary joint and a motor C, and the rotary joint is controlled by the motor C according to the control module.

4. The variable length continuous type robot according to claim 1, characterized in that: A motor A is set in the control box, and the motor A is connected to the drive line through a coupling. A tension sensor is installed on the drive line. The signal collected by the tension sensor is transmitted to a data acquisition card, which is then uploaded to the control module and the host computer.

5. A method for capturing a variable-length continuous robot, using the variable-length continuous robot according to any one of claims 1 to 4, characterized in that: Based on the known target position and size, motors B and C are adjusted to achieve the desired extension and rotation angles. The flexible gripper then forms an envelope to form a bending angle to capture the target. Specifically, the following steps are performed: Planar rotation: Motor C is used to realize the horizontal rotation of the base joint and determine the capture direction according to the location of the target. Adjust the length. After the plane rotation is completed, the effective capture length extension is determined according to the size and shape of the target, and the extension is adjusted by motor B. After the winding capture is adjusted to the appropriate length, the driving line begins to tighten and capture the target. The motor A controls the driving line to realize the deformation of the flexible capture device and form a full envelope to complete the capture of the target.

6. The capture method according to claim 5, characterized in that: The bending angle is predicted using RBF neural network when the current tension of the driving line is known. , bending angle , elongation and rotation angle , predict the unique bending angle at the next moment , when the prediction angle satisfies When , the target is considered to be fully enveloping.

7. The capturing method according to claim 6, characterized in that: When motor B and motor C reach the specified state and stop, they will follow an angle. Drive motor A and meet the predicted angle according to the judgment conditions, with Drive motor A to clamp.

8. The capturing method according to claim 7, characterized in that: During the process of forming a full envelope and grasping the target, the angular velocity of motor A will capture a sudden change, that is, the angular velocity drops sharply. Based on this sudden change, it is determined whether the target has been grasped. Otherwise, motor A continues to drive until it captures a sudden change in angular velocity.

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