CN-117086906-B - Rope-traction type rigidity-variable flexible gripper

CN117086906BCN 117086906 BCN117086906 BCN 117086906BCN-117086906-B

Abstract

The invention provides a rope-traction type rigidity-variable flexible gripper which comprises a driving assembly, a connecting assembly, a rigidity-variable grabbing unit, a driving rope and a sensor assembly. The appearance of the variable-rigidity grabbing unit is fixed on the reconnection assembly like a clamp, the variable-rigidity grabbing unit is connected with the driving assembly through the driving rope, the variable-rigidity grabbing unit is opened and closed under the pulling of the driving rope, rigidity adjustment is carried out on the variable-rigidity grabbing unit according to the hardness attribute of the grabbed object sensed by the sensor assembly, and finally object grabbing is achieved. The flexible gripper has the characteristics of strong gripping self-adaption and good gripping precision, and can be applied to gripping of various objects.

Inventors

ZHAO YANZHI
DONG LIMING
SHAN YU
Pei Changlei

Assignees

燕山大学

Dates

Publication Date: 20260505
Application Date: 20231010

Claims (9)

1. The rope-pulling type rigidity-variable flexible gripper is characterized by comprising a driving assembly, a connecting assembly, a rigidity-variable grabbing unit, a driving rope and a sensor assembly; The variable-rigidity grabbing unit is fixed on the connecting assembly in a clamp-like shape, the driving assembly is connected with the variable-rigidity grabbing unit by means of the driving rope, the variable-rigidity grabbing unit is opened and closed under the pulling of the driving rope, and the sensor assembly is used for detecting the hardness of a grabbed object and adjusting the rigidity of the variable-rigidity grabbing unit based on the detected hardness of the grabbed object; The driving assembly comprises a driving motor and a boss disc, the driving motor drives the boss disc to rotate, the upper surface of the boss disc is in a circular disc shape, the lower part of the boss disc is in a reverse cone shape, and a plurality of circular threading holes which are uniformly distributed along the circumferential direction and are equal in size are formed in the edge of the circular disc shape; The connecting assembly comprises a flange plate, a protective cover and a connecting seat, wherein the flange plate is positioned at the topmost end of the gripper, the upper end of the flange plate is used for being connected with a remote operation arm, the lower end of the flange plate is connected with the protective cover, the appearance of the protective cover is in a boss shape, and the connecting seat is arranged in the protective cover and is used for connecting the driving assembly and the variable rigidity grabbing unit; The variable-rigidity grabbing unit comprises a variable-rigidity sealing device and grabbing units, wherein a plurality of grabbing units are stacked together and packaged by means of the variable-rigidity sealing device, and dynamic rigidity adjustment is achieved by changing the internal air pressure of the variable-rigidity grabbing units; The whole grabbing units are in a clip shape, the opening ends of the grabbing units are tail ends and are connected with the protective cover, and the tail ends of the grabbing units are provided with two rows of threading holes which are uniformly spaced; The driving ropes comprise a first driving rope and a second driving rope, the first driving rope and the second driving rope are respectively arranged at two sides of the variable-rigidity grabbing unit, and threading is completed in a parallel or crossed mode; the bending angle theta of the variable-rigidity grabbing unit when grabbing an object is expressed as an included angle between a tangent line of the final end point of the sensor and an extension line of the initial position of the sensor, X is a displacement value of the bending degree of the flexible gripper during grabbing, and each bending angle corresponds to one displacement value X, namely the bending angle theta is a function which is positively correlated with X; And carrying out data processing and fusion on the pressure signal and the bending angle signal which are monitored in real time, calculating the hardness of the object and defining the hardness by H in the process of identifying the hardness of the object, wherein the larger the H value is, the larger the hardness of the object is, and the calculation formula of the hardness H of the object is: ; Wherein F is the contact pressure measured when grabbing an object, and θ is the measured bending angle; And adjusting the internal air pressure of the variable-rigidity grabbing unit based on the calculated object hardness, and when the calculated object hardness H is greater than or equal to a hardness threshold H 0 , inflating the variable-rigidity grabbing unit to reduce the rigidity of the variable-rigidity grabbing unit, and controlling the flexible grippers to stably grab the grabbed object.
2. The rope-pulling type rigidity-variable flexible gripper according to claim 1, wherein the boss disc top is provided with a pin groove for connecting with a motor shaft of a driving motor, and the tail end of the motor shaft is inserted into the pin groove by means of a shaft pin to drive the boss disc to rotate.
3. The rope-pulling type rigidity-variable flexible gripper according to claim 2, wherein the number of threading holes at the edge of the surface of the boss disc, the total number of two rows of threading holes at the opening end of the rigidity-variable grabbing unit and the total number of threading holes at the two sides of the executing end of the rigidity-variable grabbing unit are equal.
4. The tethered variable stiffness flexible grip of claim 1, wherein the sensor assembly includes a tortuosity sensor and a thin film pressure sensor; The bending sensor comprises a signal conversion unit and a strip-shaped sensing unit, wherein the signal conversion unit is placed in a sensor limiting groove on the side edge of the protective cover, and the strip-shaped sensing unit is attached to the outer surface of the variable-rigidity grabbing unit and used for detecting the bending angle of the variable-rigidity grabbing unit when grabbing objects.
5. The rope-pulling type rigidity-variable flexible gripper according to claim 4, wherein the film pressure sensor is attached to the inner surface of the rigidity-variable gripping unit and used for detecting contact pressure when gripping an object.
6. The rope-pulled rigidity-variable flexible gripper according to claim 4, wherein the strip-shaped sensing unit is a Flex bending sensor.
7. The rope-pulled type rigidity-variable flexible gripper according to claim 1, wherein the rigidity-variable gripping unit is provided with at least three layers of gripping units.
8. The rope-pulled rigidity-variable flexible gripper of claim 1 wherein said rigidity-variable sealing means is a sealed bag.
9. A gripping method based on the rope-pulled type rigidity-variable flexible gripper according to claim 1, which is characterized by comprising the following steps: S1, in an initial state of a grabbing task, an execution end of a grabbing unit is in an opening shape, and a driving rope is in a loose state; s2, placing the gripped object in a range which can be gripped by the variable-rigidity gripping unit, controlling the motor to rotate, driving the boss disc to rotate synchronously with the motor, passively changing a driving rope tied on the boss disc from a loose state to a tight state, pulling clamping jaws at two sides of the variable-rigidity gripping unit to shrink inwards, and controlling the motor to stop when the clamping jaws completely wrap and attach the object; s3, judging hardness attribute of the object according to the sensing signal acquired by the sensor assembly, adjusting internal air pressure of the variable-rigidity grabbing unit based on the hardness attribute of the object, further changing rigidity of the variable-rigidity grabbing unit, and finally controlling the flexible grippers to stably grab the grabbed object; S4, after the grabbing is finished, the variable-rigidity grabbing unit is restored to an initial air pressure state, the motor is controlled to rotate reversely, the boss disc rotates in the opposite direction, the driving rope is further enabled to outwards open the variable-rigidity grabbing unit, an object is placed, and the working process is finished.

Description

Rope-traction type rigidity-variable flexible gripper Technical Field The invention relates to the field of robot end execution, in particular to a rope-pulling type rigidity-variable flexible gripper. Background At present, the rigid manipulator mostly uses the rigid clamping jaw as the structural body, so that the quick, accurate and stable working effect can be realized when the target object is grabbed, and the rigid manipulator is widely applied in various industrial fields, but is usually designed for objects with specific shapes and sizes, and can not show enough adaptability and flexibility for objects with special shapes, curves or irregular shapes, so that the grabbing effect is poor. With the development of manipulator technology, soft manipulators can better handle irregularly shaped objects and perform more complex gripping and handling tasks due to their flexibility and deformability. This allows the soft hand to be more flexible and adaptable in handling various tasks. Furthermore, grasping and delivering are the main ways for robots to perform human-machine interaction. When the grabbing robot performs man-machine interaction operation, different tasks are required to be executed, and the safety of man-machine interaction is important. Compared with the traditional rigid grabbing robot, the soft grabbing robot has the advantage of high safety index. The chinese patent application of publication No. CN107718021a discloses a pneumatic multi-finger type soft manipulator, in which three soft finger units can realize large-scale bending deformation, but because of the pneumatic driving mode and no rigid support in the fingers, the problem of unstable gripping of the object due to insufficient gripping property during gripping is solved. The Chinese patent application with publication number CN113370241A discloses a multi-finger type soft manipulator with a net structure, which is driven by a rope to pull four soft fingers to open and close, has the characteristic of large grabbing range, but has difficulty in grabbing small rod pieces and plate objects. Disclosure of Invention In order to solve the defects in the prior art, the invention aims to provide the rope traction type rigidity-variable flexible gripper, which adopts a stepping motor to directly drive an execution end of a rope traction gripping unit to realize opening and closing of the flexible gripper, judges hardness properties of an object according to sensing signals acquired by a sensor assembly, and finally realizes rigidity-variable intelligent gripping of the object according to judging results. The invention provides a rope-pulling type rigidity-variable flexible gripper, which comprises a driving assembly, a connecting assembly, a rigidity-variable grabbing unit, a driving rope and a sensor assembly, wherein the driving assembly is connected with the connecting assembly; The variable-rigidity grabbing unit is fixed on the connecting assembly in a clamp-like shape, the driving assembly is connected with the variable-rigidity grabbing unit by means of the driving rope, the variable-rigidity grabbing unit is opened and closed under the pulling of the driving rope, and the sensor assembly is used for detecting the hardness of a grabbed object and adjusting the rigidity of the variable-rigidity grabbing unit based on the detected hardness of the grabbed object; The driving assembly comprises a driving motor and a boss disc, the driving motor drives the boss disc to rotate, the upper surface of the boss disc is in a circular disc shape, the lower part of the boss disc is in a reverse cone shape, a plurality of circular threading holes which are uniformly distributed along the circumferential direction and are equal in size are formed in the edge of the circular disc shape, and the driving rope sequentially penetrates through the threading holes in the disc; The connecting assembly comprises a flange plate, a protective cover and a connecting seat, wherein the flange plate is positioned at the topmost end of the gripper, the upper end of the flange plate is used for being connected with a remote operation arm, the lower end of the flange plate is connected with the protective cover, the appearance of the protective cover is in a boss shape, and the connecting seat is arranged in the protective cover and is used for connecting the driving assembly and the variable rigidity grabbing unit; The variable-rigidity grabbing unit comprises a variable-rigidity sealing device and grabbing units, wherein a plurality of grabbing units are stacked together and packaged by means of the variable-rigidity sealing device, and dynamic rigidity adjustment is achieved by changing the internal air pressure of the variable-rigidity grabbing units; The two sides of the gripping units are provided with threading holes uniformly distributed along the bottoms of the gripping units, and a driving rope sequentially penetrates through the threading holes to be co