CN110614648A

CN110614648A - Under-actuated self-adaptive two-finger clamping jaw

Info

Publication number: CN110614648A
Application number: CN201910751089.8A
Authority: CN
Inventors: 刘冬; 丛明; 缪跃; 吕志
Original assignee: Jiangsu Research Institute Co Ltd of Dalian University of Technology
Current assignee: Jiangsu Research Institute Co Ltd of Dalian University of Technology
Priority date: 2019-08-15
Filing date: 2019-08-15
Publication date: 2019-12-27

Abstract

The invention discloses an under-actuated self-adaptive two-finger clamping jaw, and belongs to the field of end effectors of robots. The two-finger gripper includes a finger, a base, and a flange. Two fingers of the two-finger clamping jaw consist of 4 finger joints, have 2 degrees of freedom and are driven by 1 micro motor. Each knuckle is connected in a twisting mode through matching of the shaft and the hole, and the fingers can achieve opening and closing actions. The two finger grippers may be connected to the robotic arm by flanges. The invention has high flexibility, simple and compact structure and can effectively realize the self-adaptive grabbing of objects with different sizes and shapes.

Description

Under-actuated self-adaptive two-finger clamping jaw

Technical Field

The invention belongs to the field of end effectors of robots, and relates to an under-actuated self-adaptive two-finger clamping jaw.

Background

Currently, most robot end effectors fall into three major categories. One is a low degree of freedom clamp designed to accomplish a single task, one is a multi-fingered dexterous hand with multiple degrees of freedom, and the other is an under-actuated clamp. The low-freedom-degree clamp is simple, stable in performance and low in cost. However, the problem is that the operation is single, the flexibility is poor, and only a specific operation can be completed. They mostly have only one degree of freedom and can only perform one simple action. The multi-degree-of-freedom dexterous hand is very flexible, mostly imitates the design of hands, can grab irregular-shaped objects, and can complete complex actions. However, due to the increase of the degree of freedom, the mechanical structure is necessarily complex, the transmission is not stable enough, and the robustness is poor. In addition, in order to complete complex grabbing actions, a plurality of sensors are required to be configured as feedback, so that the integration difficulty of the control system is increased, and the cost is greatly increased. In order to optimize the disadvantages of both grippers, underactuated grippers are therefore emerging. The underactuated clamp holder is an end effector, and an actuating mechanism of the underactuated clamp holder is less than the degree of freedom, so that the degree of freedom is increased, the adaptability of the underactuated clamp holder is stronger, and the structure is not too complex. Currently, there are TH-1 hands of the university of Qinghua, Harada hands of the California's college of science, HIT/DLR hands of the university of Harbin industry, etc., which have achieved some success in the study of end-point clamping hands.

An end effector multi-finger dexterous hand, as disclosed in patent CN102085662A, is composed of an electric thumb, four electric fingers and a mechanical palm. Except that the thumb has 4 main degrees of freedom, the structures of the other fingers are the same, and the fingers all have three main degrees of freedom and one driven degree of freedom. The fingers are coupled with the gear through a link mechanism for transmission, and each finger is driven by a motor. The defects that the gear transmission ratio of the joints of the fingers except the thumb is determined, the fingers can only be bent at a determined speed, the adaptability of grabbing objects is poor, the structure is relatively complex, and the palm size is large. Another underactuated actuator, for example, patent CN109732639A, is a liquid isobaric underactuated bionic robot paw, which is composed of a base, a driving mechanism and fingers, and realizes isobaric actuation by hydraulic actuation and pipeline hydraulic through manner. The hydraulic drive mode is adopted, the problem that a transmission mechanism is complex is solved, but the requirement on pipeline tightness is strict.

Currently, the difficulty and key technology of end effector research are in the research of structural design and driving manner. If the multi-degree-of-freedom grabbing function is realized, the structural design and a transmission system are necessarily very complex; if the mechanical structure is simplified, the multiple degrees of freedom and high adaptability of the fingers cannot be guaranteed. Therefore, how to simplify the mechanical transmission structure under the condition of satisfying the high-adaptability grabbing function constitutes a research hotspot for the present day.

Disclosure of Invention

The invention aims to provide an under-actuated self-adaptive two-finger clamping jaw, which has 2 degrees of freedom, simple and reliable structure and strong adaptability and can realize enveloping and two-finger clamping. The fixture may be used in a variety of automated scenarios, such as automated assembly lines, mobile operations in structured or unstructured environments, remote operations, fixture-less robotic welding, machine management, parts sorting, and bin picking, among others.

In order to achieve the purpose, the invention adopts the technical scheme that:

an under-actuated self-adaptive two-finger clamping jaw comprises a flange, a base and two fingers, wherein each finger is a link mechanism. One end of the flange is connected with the base through a screw perpendicular to the bottom surface of the base, and the other end of the flange is used for connecting the clamping jaw with devices such as a mechanical arm and the like; the base is a buckling type shell mechanism, a motor, a driving controller and a transmission mechanism are arranged in the base, and internal components are arranged in parallel with the base; the finger part is a five-link mechanism, two fingers are vertically installed with the base under the closed state, wherein the near end of the base is provided with two connecting rods, a rod piece connected with the transmission part is named as a driving knuckle, the other near end connecting rod of the base is named as a rotating knuckle, the connecting rod connected with the driving rod is named as a limiting knuckle, the clamping knuckle is connected with the limiting knuckle and the rotating connecting rod and is provided with a rough contact surface; the fingers are connected with a shaft parallel to the bottom surface of the base through driving knuckles, and the driving shaft is named as a driving shaft; connecting shafts of the other knuckles and the knuckle are respectively named as a finger shaft I, a finger shaft II, a finger shaft III and a finger shaft IV from near to far from the base, the finger shaft I is connected with the rotating knuckle and the base, the finger shaft II is connected with the driving knuckle and the limiting knuckle, the finger shaft III is connected with the limiting knuckle and the clamping knuckle, and the finger shaft IV is connected with the clamping knuckle and the rotating knuckle; wherein, a torsion spring which is superposed with the axis of the finger shaft is arranged on the finger shaft I and is arranged in the base; the shaft is connected with the knuckle through an oilless bushing, and the end face of the oilless bushing is contacted with the side face of the finger.

The base body of the base is formed by combining a first base shell, a second base shell and a position fixing piece. One part of the base shell is provided with a positioning hole and a finger mounting groove, one end of the base shell is provided with a torsion spring limiting hole, a speed reducer fastening positioning hole, a motor fastening positioning hole, a driving controller fastening positioning hole, a worm fastening positioning hole and a turbine shaft positioning hole, wherein the speed reducer fastening positioning hole, the motor fastening positioning hole and the driving controller fastening positioning hole are located on the same reference, the upper part of the base shell is provided with the worm fastening positioning hole, the uppermost end of the base shell is provided with the turbine shaft positioning hole, one corner of the base shell is respectively provided with a thread. The two end surfaces of the base shell are provided with threaded fastening holes at positions corresponding to one corner of the base shell, and the side surfaces of the two end surfaces of the base shell are provided with semicircular lead through holes and finger mounting grooves. The fasteners are respectively a first speed reducer fastener, a second speed reducer fastener, a first motor fastener, a second motor fastener and a worm fastener, the end faces of the first speed reducer fastener and the second motor fastener are semi-circles, and threaded holes are formed in the top faces of the first speed reducer fastener and the second motor fastener. The first speed reducer fastener and the first motor fastener are fixedly positioned with the first base shell through the two rows of holes in the left side, and the second speed reducer fastener and the second motor fastener are fixedly positioned and fastened with the first speed reducer fastener and the first motor fastener through top threaded holes respectively in the upper portions of the speed reducer and the motor. The worm fastener is fixed with the first base shell through the positioning hole on the upper portions of the motor and the speed reducer. The axes of the motor and the output shaft of the speed reducer are parallel to the intersecting line of the bottom surface and the side surface of the base, the output shaft of the motor is provided with a first cylindrical gear, the first cylindrical gear is meshed with a second cylindrical gear, the second cylindrical gear is coaxially and fixedly installed with a worm, the worm is a double-rotation-direction worm and is installed through a worm fastener, and the worm fastener are provided with oil-free bushings. The turbine hole is D type hole, and is fixed with the installation of turbine D type axle, and turbine D type axle head portion is the step shaft, and base worm fastening locating hole upper end shaft hole is coaxial, through oilless bush erection joint. The torsion spring and the shaft are coaxially installed, one end of the torsion arm of the torsion spring is fixedly installed with the shaft I, and the other end of the torsion arm of the torsion spring is fixedly installed with the torsion spring limiting hole of the base shell. The first base shell and the second base shell are fixedly connected through threaded fastening holes.

The two finger parts are identical in structural layout, are symmetrical about the center line of the base and comprise driving knuckle parts, limiting knuckle parts, clamping knuckle parts and rotating knuckle parts. The D-shaped shaft of the turbine protrudes out of the shaft shoulder and is mounted with the end face of the turbine in a fitting mode, a D-shaped hole is formed in one end face of the drive knuckle and is mounted with the end face of the turbine in a fitting mode, the D-shaped shaft of the turbine is fixed together through the three of the D-shaped shaft of the turbine, the D-shaped shaft of the turbine is fixedly mounted through matching with the first base shell and the second base shell positioning hole, and the oil-free bushing. The limiting knuckle is connected and mounted with the driving knuckle through a second finger shaft, the driving knuckle is matched with a groove at one end of the limiting knuckle, and an oilless bushing is mounted on the matching surface of the shaft hole; the groove at the other end of the limiting knuckle and the clamping knuckle are installed in a matched mode through a finger shaft III, and oil-free bushes are arranged on the inner side of the groove and the end face of the clamping knuckle; the other end of the clamping knuckle is matched with the groove of the rotating knuckle and is connected and installed through a finger shaft IV, and the inner side of the groove and the end surface of the clamping knuckle are provided with oilless bushings; the other end of the rotating knuckle is matched with the base shell through a first finger shaft, and an oilless bushing is arranged on the matching surface of the shaft hole; and the center positions of the side surfaces of the finger shaft II, the finger shaft III and the finger shaft IV are provided with jackscrew holes, and finger knuckles and the shafts are tightly connected through jackscrews.

The invention has high flexibility, simple and compact structure and can effectively realize the self-adaptive grabbing of objects with different sizes and shapes.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic diagram of the left side of the finger according to the present invention;

FIG. 3 is a schematic diagram of the finger movement principle of the present invention;

FIG. 4 is a schematic diagram of the finger movement principle of the present invention;

FIG. 5 is a schematic diagram of the finger movement principle of the present invention;

FIG. 6 is a schematic view of a base transmission structure according to the present invention;

in the figure: 1, finger tip; 2, clamping knuckle; 3 connecting the shaft; 4, rotating the knuckle; 5, limiting knuckle; 6 driving knuckle; 7, a base; 8, connecting a flange; 9 grasping an object; 10 a four-bar mechanism; 301 oilless liner; a clamp spring for the shaft 302; 701 left-hand turbine; a 702D-type shaft; 703 double-handed worm; 704 cylindrical gear; 705 a cylindrical gear; 706 reducer support base; 707 a motor base; 708 a torsion spring; 709 oil-free lining; 710 a worm bearing mount; 711 drive controller.

Detailed Description

The specific structure and operation of the present invention will be further described with reference to the accompanying drawings.

The invention relates to an under-actuated self-adaptive two-finger clamping jaw, which comprises a base and two fingers, wherein the two finger units comprise fingertips 1, clamping finger sections 2, a connecting shaft 3, a rotating finger section 4, a limiting finger section 5 and a driving finger section 6, as shown in figure 1. The two fingers are in a stretched state, and the rotating knuckle is vertically arranged with the bottom surface of the base; the knuckle is connected with the knuckle through a rotating shaft. And 8, the connecting flange is used for connecting the clamping jaw with other mechanical arms, the large end face of the flange is arranged in parallel with the bottom surface of the base, and the small end face of the flange is arranged in parallel with the connecting face of the mechanical arm.

As shown in figure 2, the two fingers are symmetrically arranged in the direction of the normal of the plane of the base, the fingers are composed of four parts, namely a clamping knuckle 2, a rotating knuckle 4, a limiting knuckle 5 and a driving knuckle 6, and the knuckles are connected through a shaft. The driving joint 6 is connected with the internal transmission structure through the D-shaped notch and used as a driving rod piece of a finger, the other end of the driving joint 6 is inserted into the groove of the limiting knuckle 5, and a limiting convex rod is arranged on the driving joint. The groove at the other end of the limiting knuckle 5 is connected with the protruding end of the clamping knuckle 2 in a twisting mode through a shaft 3, and an oilless bushing 301 and a shaft clamp spring 302 are installed on the side of the shaft end. The other protruding end of the clamping knuckle 2 is matched with the groove end of the rotating knuckle 4 and is connected with the upper portion of the clamping knuckle 2 in a twisting mode through a shaft, and the upper portion of the clamping knuckle 2 is fixed with the fingertip 1 in a parallel mode. The rotating knuckle 4 is connected with the base in a twisting mode through a shaft, 708 is a torsion spring, one supporting end of the torsion spring is fixedly connected with the fingers, the other end of the torsion spring is fixedly connected with the base, and the torsion force of the torsion spring always tends to enable the clamping jaws to be in a closed state.

The finger grabbing motion track is shown in fig. 3, 4 and 5, and the motion track is the process from opening to closing of the fingers. Fig. 3 shows the maximum finger opening state, and due to the torsional clamping force of the torsion spring 708, the clamping jaw is in the clamping state, the limit stop block is in contact with the limit knuckle 5, the contact force caused by the torsional force and the driving force solidifies the rotating knuckle 4 and the driving knuckle 6, the five-bar finger mechanism is simplified into the four-bar mechanism 10, and the gripped object 9 is in contact with the contact surface of the fingertip 1 to generate the clamping friction force, so that the gripped object is gripped. Fig. 4 shows the state that the fingers grab the object in the middle, the knuckle 6 is driven to rotate by a certain angle, at the moment, the five-bar finger mechanism is simplified into a four-bar mechanism 10, and the finger tip 1 is perpendicular to the bottom surface of the base in the operation process. FIG. 5 shows the final closed state of the finger, with the rotating knuckle 4 parallel to the plane of the fingertip 1 and the parallel plane perpendicular to the bottom surface of the base; the fingertip 1 is perpendicular to the bottom surface of the base in the operation process.

The base transmission structure is shown in fig. 6, and the base 7 is provided with a finger mounting groove and connected in a buckling mode. The torsion spring 708 is coaxially installed with the shaft, one end of the torsion spring 708 is fixedly connected with the side wall of the base through a limiting hole, and the other end of the torsion spring 708 is fixedly connected with the shaft. 711 is a driving controller, and the bottom surface of the driving controller 711 is parallel to the side surface of the base and is connected and installed through a positioning hole. 707 a motor base, which is divided into a motor upper cover and a motor base, fixed by bolts, and a top screw hole of the upper cover for installing a top screw to prevent the motor from rotating; 706 is the reduction gear supporting seat, and the reduction gear supporting seat divide into reduction gear supporting seat upper cover and reduction gear supporting seat base, and through the bolt fastening, reduction gear supporting seat upper cover jackscrew hole is used for installing the jackscrew, prevents that the reduction gear from rotating. 704. 705 is a cylindrical gear used for transmitting the rotation power of the output shaft of the motor, and the cylindrical gear 705 is coaxially arranged with the output shaft of the motor and is fixed with the output shaft of the motor through a jackscrew hole on a gear boss; the cylindrical gear 704 is coaxially arranged with the worm and fixedly connected with the worm through a top thread hole on the boss; the end faces of the cylindrical gear 704 and the cylindrical gear 705 are overlapped, and the two gears are assembled in a meshing mode. 703 is a bidirectional worm, the left end is a left-handed worm, the right end is a right-handed worm, and the worm and the turbine are assembled in a meshing way. The worm bearing seat 710 is used for supporting a double-rotation-direction worm, and an axial hole is formed in the end face of the worm bearing seat 710 and is coaxially mounted with the double-rotation-direction worm 703; 709 is oil-free bush, and is installed coaxially with the double-rotation-direction worm, and the end face of the oil-free bush is contacted with the end face of the worm supporting seat, so that the friction force is reduced. The 701 is a left-handed worm wheel which is meshed with a left-handed worm at the left end of the double-handed worm 703, the end face of the left-handed worm wheel is provided with a D-shaped groove hole which is coaxially matched and installed with a D-shaped shaft 702, and the D-shaped shaft is matched and installed with a D-shaped groove hole of the driving knuckle 6. The motor rotates and transmits the rotation to the cylindrical gear 704; the cylindrical gear 704 is fixedly connected with the double-rotation-direction worm 703, and the double-rotation-direction worm 703 rotates; the double-rotation-direction worm 703 is meshed with the turbine, the turbine 701 rotates, the turbine 701 is fixedly connected with the driving knuckle 6, the driving knuckle 6 rotates, and finally the motion action of the under-actuated self-adaptive two-finger clamping jaw is achieved.

The above-mentioned embodiments only express the embodiments of the present invention, but not should be understood as the limitation of the scope of the invention patent, it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the concept of the present invention, and these all fall into the protection scope of the present invention.

Claims

1. An under-actuated adaptive two-finger gripper device, characterized in that: the two-finger clamping jaw device comprises a base (7), two finger units, a connecting flange (8) and a rotating shaft (3); each finger is a link mechanism and has 2 degrees of freedom, each finger unit comprises a driving knuckle (6), a limiting knuckle (5), a clamping knuckle (2) and a rotating knuckle (4), the clamping knuckle (2) is connected with a fingertip (1), the knuckles are connected with each other through rotating shafts (3), and the knuckles are fixedly connected with the shaft through jackscrews; the connecting flange (8) is arranged below the base (7) and used for connecting the two-finger clamping jaw with other mechanical arms, the large end face of the connecting flange (8) is arranged in parallel with the bottom surface of the base (7), and the small end face of the connecting flange (8) is arranged in parallel with the connecting surface of the mechanical arm;

the two finger units are symmetrically arranged in the direction of the plane normal of the base (7), and the two fingers are arranged in a straight state in a way that the rotating knuckle (4) is vertical to the bottom surface of the base (7); one end of the driving joint (6) is connected with the internal transmission structure through the D-shaped notch to serve as a driving rod piece of the finger, the other end of the driving joint (6) is inserted into a groove at one end of the limiting knuckle (5), and a limiting convex rod is arranged on the driving joint (6); a groove at the other end of the limiting knuckle (5) is in torsional connection with a protruding end of the clamping knuckle (2) through a connecting shaft (3), and an oilless bushing (301) and a shaft clamp spring (302) are arranged on the shaft end side; the other protruding end of the clamping knuckle (2) is matched with the groove end of the rotating knuckle (4) and is connected with the groove end of the rotating knuckle in a twisting mode through a shaft, and the upper portion of the clamping knuckle (2) is fixed with the fingertip (1) in parallel;

the base (7) is provided with a finger mounting groove, the rotating knuckle (4) is in torsional connection with the base (7) through a shaft, and the base (7) comprises a left-handed worm wheel (701), a D-shaped shaft (702), a double-handed worm (703), a cylindrical gear (704), a cylindrical gear (705), a reducer supporting seat (706), a motor seat (707), a torsion spring (708), an oilless bushing (709), a worm bearing seat (710) and a driving controller (711); one end of the torsion spring (708) is fixedly connected with the side wall of the base through a limiting hole, the other end of the torsion spring is fixedly connected with the fingers, and the torsion force of the torsion spring (708) always tends to make the clamping jaws closed; the bottom surface of the driving controller (711) is parallel to the side surface of the base (7) and is connected and installed through a positioning hole; the motor base (707) is divided into a motor upper cover and a motor base and is fixed through bolts, and a jackscrew is installed in a jackscrew hole of the motor upper cover to prevent the motor from rotating; the speed reducer supporting seat (706) comprises a speed reducer supporting seat upper cover and a speed reducer supporting seat base, and is fixed through bolts, and a jackscrew hole of the speed reducer supporting seat upper cover is used for installing a jackscrew to prevent the speed reducer from rotating; the cylindrical gears (704) and (705) are used for transmitting the rotating power of the output shaft of the motor, and the cylindrical gears (705) are coaxially arranged with the output shaft of the motor and fixed with the output shaft of the motor through jackscrew holes in a gear boss; the cylindrical gear (704) is coaxially arranged with the worm and fixedly connected with the worm through a top thread hole on the boss; the end surfaces of the cylindrical gear (704) and the cylindrical gear (705) are superposed, and the two gears are assembled in a meshing way; the worm (703) is a double-rotation-direction worm, and the worm is meshed with the turbine and assembled; the worm bearing seat (710) is used for supporting the double-rotation-direction worm (703), and the end face of the worm bearing seat (710) is provided with a shaft hole which is coaxially arranged with the double-rotation-direction worm (703); the oilless bushing (709) is coaxially mounted with the double-rotation-direction worm (703), and the end face of the oilless bushing is in contact with the end face of the worm support seat and is used for reducing friction force; the left-handed worm wheel (701) is meshed with the left-handed worm of the double-handed worm (703), a D-shaped slotted hole is formed in the end face of the left-handed worm wheel (701) and is coaxially matched with the D-shaped shaft (702), and the D-shaped shaft (702) is matched with the driving knuckle (6);

the motor rotation is transmitted to the cylindrical gear (704) to drive the cylindrical gear to rotate; the cylindrical gear (704) is fixedly connected with the double-rotation-direction worm (703), and then the double-rotation-direction worm (703) rotates; the double-rotation-direction worm (703) is meshed with the turbine, the turbine (701) rotates, the turbine (701) is fixedly connected with the driving knuckle (6), and the driving knuckle (6) rotates to realize the motion action of the under-actuated self-adaptive two-finger clamping jaws.