CN212193200U

CN212193200U - Pulley type under-actuated three-joint manipulator

Info

Publication number: CN212193200U
Application number: CN202020876413.7U
Authority: CN
Inventors: 郭瑞峰; 黄亚东; 贾榕; 闫浩; 胡星
Original assignee: Xian University of Architecture and Technology
Current assignee: Xian University of Architecture and Technology
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2020-12-22
Anticipated expiration: 2030-05-22

Abstract

The utility model discloses a pulley type underactuated three-joint manipulator, including three underactuated finger, three underactuated finger interval sets up on strutting arrangement, and every underactuated finger has three degree of freedom, and strutting arrangement's bottom is provided with driving system, and driving system passes through wire rope to be connected with the finger fingertip of three underactuated finger respectively, is provided with differential mechanism between wire rope and the three underactuated finger. The utility model discloses simple structure, reasonable in design snatchs in a flexible way, reliably, possesses fine shape closed characteristic.

Description

Pulley type under-actuated three-joint manipulator

Technical Field

The utility model belongs to the technical field of mechanical production, concretely relates to pulley type is owed and is driven three joint manipulators.

Background

Due to the overall development of industrial automation and the continuous improvement of scientific technology, the improvement of working efficiency is urgent. The requirement of industrial automation cannot be met by simple manual work, so that the requirement of industrial automation is met by using advanced equipment to produce automatic machinery to replace human labor. The manipulator is one of important products in the development process, improves the labor production efficiency, can replace human beings to finish high-intensity, dangerous and repeatedly boring work, reduces the labor intensity of the human beings, and achieves two purposes. In the mechanical industry, manipulators are increasingly widely used, and can be used for assembling parts and transporting, loading and unloading machined workpieces, and are particularly more commonly used on automatic numerical control machines and combined machines.

Currently, robots have been developed as an important component of flexible manufacturing systems and flexible manufacturing units. The machine tool equipment and the manipulator form a flexible processing system or a flexible manufacturing unit together, so that a huge workpiece conveying device can be saved, the structure is compact, and the adaptability is strong. However, the industrial manipulator technology and the engineering application level and the foreign ratio of the industrial manipulator technology in China have certain distance, the application scale and the industrialization level are low, the research and the development of the manipulator directly influence the improvement of the automatic production level of the mechanical industry in China, and the improvement is necessary from the economic and technical consideration. Therefore, it is important to design and study the manipulator.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that not enough among the above-mentioned prior art is directed against, provide a pulley type underactuated three-joint manipulator, can indicate three-joint manipulator through single motor drive and realize snatching the operation, the manipulator can be adaptive to the diameter and be about 100 mm's globular and various special-shaped object to snatch reliably, possess fine shape closed characteristic.

The utility model adopts the following technical scheme:

the pulley type under-actuated three-joint manipulator comprises three under-actuated fingers, wherein the three under-actuated fingers are arranged on a supporting device at intervals, each under-actuated finger has three degrees of freedom, a power system is arranged at the bottom of the supporting device, the power system is respectively connected with finger tips of the three under-actuated fingers through a steel wire rope, and a differential mechanism is arranged between the steel wire rope and the three under-actuated fingers.

Specifically, the power system comprises a transmission case, the transmission case is connected with one side of a fixing plate of the supporting device, the other side of the fixing plate is connected with a retaining plate through three guide rods, three base joints are arranged on the retaining plate, and the three base joints are correspondingly connected with three under-actuated fingers.

Furthermore, the differential mechanism comprises a first movable pulley and a second movable pulley, the first sliding block and the second sliding block are respectively arranged on two adjacent guide rods, and the first movable pulley and the second movable pulley are correspondingly arranged on the first sliding block and the second sliding block; one end of the steel wire rope is connected with a steel wire arranged in the transmission case around a shaft, and the other end of the steel wire rope is respectively connected with the three under-actuated finger tips through the first movable pulley and the second movable pulley.

Furthermore, the steel wire rope comprises a first steel wire rope, a second steel wire rope and a third steel wire rope, one end of the first steel wire rope is connected with the motor in the transmission case, and the other end of the first steel wire rope is fixed on the first sliding block; one end of a second steel wire rope is connected with the fingertip of an under-actuated finger, and the other end of the second steel wire rope is connected with a second sliding block through a first movable pulley; and a third steel wire rope is wound on the second movable pulley, and two ends of the third steel wire rope are respectively connected with the fingertips of the remaining two under-actuated fingers.

Specifically, the under-actuated finger comprises a first knuckle, a second knuckle and a third knuckle, wherein one end of the first knuckle is connected with the base joint shaft, the other end of the first knuckle is connected with one end shaft of the second knuckle, and the other end of the second knuckle is connected with one end shaft of the third knuckle.

Furthermore, a first driving wheel is arranged on a connecting shaft of the first knuckle and the base joint, a second driving wheel is arranged on a connecting shaft at the joint of the first knuckle and the second knuckle joint, and a third driving wheel is arranged on a connecting shaft at the joint of the second knuckle and the third knuckle joint.

Furthermore, a first fixed pulley is arranged on the first knuckle, and a second fixed pulley is arranged on the second knuckle.

Further, a first spring is arranged between the first knuckle and the base joint; a second spring is arranged between the first knuckle and the second knuckle; and a third spring is arranged between the second knuckle and the third knuckle.

Specifically, a stepping motor is arranged in the transmission case, the stepping motor is connected with a driving bevel gear through a coupler, the driving bevel gear is meshed with a driven bevel gear sleeved on a steel wire shaft, and two ends of the steel wire shaft are movably connected with the protection shell through bearings respectively.

Compared with the prior art, the utility model discloses following beneficial effect has at least:

the utility model relates to a pulley type underactuated three-joint manipulator, which has 9 degrees of freedom and is driven by a motor; the transmission mechanism is formed by connecting two groups of movable pulleys in series, and the self-adaptability of the manipulator is ensured due to the rotation of the movable pulleys, namely when one finger is blocked and cannot rotate continuously, the other two fingers can still rotate continuously until the other two fingers completely contact the object to be grabbed; the underactuated mechanism among the three underactuated fingers uses a driver to drive the bending and stretching actions of the three fingers, adopts a differential mechanism formed by connecting two stages of movable pulleys in series, and has self-adaptability, namely when one or more fingers are fixed and can not move continuously due to resistance when contacting a grasped object, other fingers can move continuously, and when all the fingers stably contact the grasped object, the driving force can be uniformly distributed to all the fingers through the underactuated mechanism, and larger grasping force can be ensured as much as possible when stably grasping, and in order to ensure that the grasped object is reliable and the design is convenient and beautiful, the three fingers are uniformly distributed at 120 degrees.

Furthermore, a differential structure formed by two movable pulleys is one of important conditions for realizing the mechanical arm under-actuated principle. When one or more fingers are blocked due to obstacles and cannot move continuously, other fingers can move continuously due to the existence of the movable pulley, and the acting force is continuously transmitted to the next link.

Furthermore, the supporting device plays a role in holding the fingers up and down, the fixing plate is connected with the base joint so as to bear the whole finger part, the sliding block is arranged on the guide rod in the middle, the three guide rods play a role of a guide rail and can provide mechanical support, and the length, the width and the height of the guide rod are selected according to kinematic analysis and determined after the rope contraction and the extension length of the fingers when the grabbed object is opened or closed are determined.

Furthermore, the three under-actuated fingers are respectively fixed on a holding plate of the supporting device through corresponding base joints, and the near joint, the middle joint and the far joint respectively have one degree of freedom, so that the structural complexity of the fingers is reduced, and the requirement of envelope grabbing can be met.

Furthermore, the transmission case is mainly responsible for providing motion and power for the mechanical gripper, and more importantly, the reasonable design of the transmission case can ensure the underactuated effect and the self-adaptive performance of the manipulator, so that the three fingers and six degrees of freedom can be driven by one driving motor to move simultaneously, and when one or two fingers are obstructed due to contact with a gripped object and cannot continue to perform gripping motion, the other fingers can still continue to bend until the fingers completely contact the gripped object.

To sum up, the utility model discloses simple structure, reasonable in design snatchs in a flexible way, reliably, possesses fine shape closed characteristic.

The technical solution of the present invention is further described in detail by the accompanying drawings and examples.

Drawings

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

FIG. 2 is a diagram of the finger structure of the present invention, wherein (a) is a diagram of the structure and (b) is a diagram of the transmission;

FIG. 3 is a schematic diagram of the movement of the transmission mechanism for different finger members of the present invention;

FIG. 4 is a schematic view of the overall layout of the fingers of the present invention;

FIG. 5 is a schematic view of the transmission case of the present invention;

FIG. 6 is a schematic view of the guide bar and the support of the present invention;

fig. 7 is an assembly view of the manipulator fingers of the present invention.

Wherein: 1. a transmission case; 2. a fixing plate; 3. a slider; 3-1, a first slide block; 3-2. a second slide block; 4. a movable pulley; 4-1, a first movable pulley; 4-2, a second movable pulley; 5. a guide bar; 6. a wire rope; 6-1, a first steel wire rope; 6-2. a second steel wire rope; 6-3, a third steel wire rope; 7. a holding plate; 8. a base joint; 9. an under-actuated finger; 9-1. a first knuckle; 9-2. a second knuckle; 9-3. third knuckle; 10. a first drive wheel; 11. a first fixed pulley; 12. a second drive wheel; 13. a second fixed pulley; 14. a third drive wheel; 15. a first spring; 16. a second spring; 17. a third spring; 18 drive bevel gears; 19. winding the steel wire around a shaft; 20. a bearing; 21. a protective housing; 22. a driven bevel gear.

Detailed Description

Referring to fig. 1 and 7, the pulley type under-actuated three-joint manipulator of the present invention includes a power system, a transmission system, a supporting device and an under-actuated finger 9. The power system comprises a transmission case 1, three support devices are arranged on the transmission case 1, the number of the under-actuated fingers 9 is three, the under-actuated fingers are arranged at the top ends of the support devices at intervals, and the transmission system is arranged on the support devices. The transmission system comprises a steel wire rope 6, one end of the steel wire rope 6 is connected to a power input end, the other end of the steel wire rope 6 is respectively fixed at steel rings of finger tips of three under-actuated fingers 9 through a differential mechanism formed by connecting two stages of movable pulleys in series, and the whole finger carries out power and motion transmission through the steel wire rope 6 and driving wheels arranged at each joint.

Referring to fig. 6, the supporting device includes a fixing plate 2, a guide rod 5 and a holding plate 7; the transmission system comprises a sliding block 3, a pulley 4 and a steel wire rope 6; the fixed plate 2 is arranged on the transmission case 1, the guide rods 5 comprise three guide rods, one end of each guide rod is connected with the fixed plate 2, the other end of each guide rod is connected with the retaining plate 7, the three guide rods 5 are arranged at intervals, the first sliding block 3-1 and the second sliding block 3-2 are respectively arranged on the two adjacent guide rods 5, and the first sliding block 3-1 and the second sliding block 3-2 are correspondingly provided with a first movable pulley 4-1 and a second movable pulley 4-2; one end of the steel wire rope 6 is connected with a steel wire shaft 19 arranged in the transmission case 1, and the other end is respectively connected with three under-actuated fingers 9 through a first movable pulley 4-1 and a second movable pulley 4-2.

Referring to fig. 3 and 4, the wire rope 6 includes a first wire rope 6-1, a second wire rope 6-2 and a third wire rope 6-3, the first movable pulley 4-1 is disposed on the first guide rod through the first slider 3-1, and the second movable pulley 4-2 is disposed on the second guide rod through the second slider 3-2; one end of a first steel wire rope 6-1 is fixed on a steel wire shaft and is connected with a motor in the transmission case 1 through a bevel gear and a coupler, and the other end of the first steel wire rope is fixed on a first sliding block 3-1 and is responsible for transmitting power generated by the motor to the first sliding block 3-1; one end of a second steel wire rope 6-2 is connected with the fingertip of an underactuated finger 9 through a first driving wheel 10, a first fixed pulley 11, a second driving wheel 12, a second fixed pulley 13 and a third driving wheel 14 to drive the bending motion of the finger, and the other end of the second steel wire rope is connected with a second sliding block 3-2 through a first movable pulley 4-1 to transmit power to the second sliding block 3-2; the third steel wire rope 6-3 is wound on the second movable pulley 4-2, and two ends of the third steel wire rope are respectively connected with fingertips of the other two under-actuated fingers 9 through the corresponding first driving wheel 10, first fixed pulley 11, second driving wheel 12, second fixed pulley 13 and third driving wheel 14, and are responsible for driving finger bending movement of the two remaining under-actuated fingers 9.

Referring to fig. 5, a stepping motor is installed at the bottom of the transmission case 1, the stepping motor is connected with a driving bevel gear 18 through a coupler, the driving bevel gear 18 is in meshing transmission with a driven bevel gear 22 sleeved on a steel wire shaft 19, two ends of the steel wire shaft 15 are movably connected with a protective shell 21 through bearings 20, power generated by the stepping motor is sequentially transmitted to the driving bevel gear 18 and the driven bevel gear 22 meshed with the driving bevel gear, the steel wire shaft 19 and the driven bevel gear 18 rotate together, and meanwhile, a first steel wire rope 6-1 is wound on the steel wire shaft 15 to transmit force to a next system.

Referring to fig. 2, through functional analysis of the human hand, it is found that most of the grasping and operating processes of the human hand are mainly completed by three fingers, namely a thumb, an index finger and a middle finger, the ring finger and the little finger mainly play an auxiliary role, and the number of the fingers is 3 in order to reduce the complexity of the mechanism. The under-actuated fingers 9 comprise a first knuckle 9-1, a second knuckle 9-2 and a third knuckle 9-3, the degree of freedom of each under-actuated finger 9 is 3, and the three under-actuated fingers 9 are uniformly distributed on the retaining plate 7 at 120 degrees for the purposes of reliably gripping objects and conveniently designing and beautifying.

The base joint 8 is connected with one end shaft of the first knuckle 9-1, the other end of the first knuckle 9-1 is connected with one end shaft of the second knuckle 9-2, and the other end of the second knuckle 9-2 is connected with one end shaft of the third knuckle 9-3. A first driving wheel 10 is arranged on a connecting shaft of the first knuckle 9-1 and the base joint 8, a second driving wheel 12 is arranged on a connecting shaft at the joint of the first knuckle 9-1 and the second knuckle 9-2, and a third driving wheel 14 is arranged on a connecting shaft at the joint of the second knuckle 9-2 and the third knuckle 9-3.

The first driving wheel 10 is fixedly connected with the first knuckle 9-1, the second driving wheel 12 is fixedly connected with the second knuckle 9-2, and the third driving wheel 13 is fixedly connected with the third guide 9-3.

The base joint 8 of the finger is fixed on the holding plate 7, a torsion spring 15 is installed between the first knuckle 9-1 and the base joint 8, a torsion spring 16 is installed between the second knuckle 9-2 and the first knuckle, and a torsion spring 17 is installed between the third knuckle 9-3 and the second knuckle. The torsion spring provides certain spring force for ensuring that the finger is in a normally open state when the finger is in a natural state when not grabbing an object.

The steel wire rope winds into the first driving wheel 10 from the lower part, winds around the first driving wheel 10 for a circle, then passes through the first fixed pulley 11, winds into the second driving wheel 12 from the lower part, winds around the second driving wheel 12 for a circle, then passes through the second fixed pulley 13, winds into the third driving wheel 14 from the lower part, winds around the driving wheel 14 for a circle, and finally is fixedly connected to the finger tip.

Because the steel wire rope can only bear pulling force and can not bear pressure or pushing force, the manipulator needs to keep a normally open state, the steel wire rope is pulled to bend and grab the fingers, the torsion spring at the joint of the manipulator restores to the initial position, and therefore a certain initial angle is needed to ensure the normally open state of the fingers when the torsion spring is installed. However, according to the design principle of the fingers, the stiffness of the spring at each joint directly affects the motion state of the fingers, so that the stiffness of the spring needs to be selected by comprehensively considering various factors, the stiffness of the torsion spring of each joint can be preliminarily determined through calculation, the initial angle during installation can be further determined, and the initial angle during installation of the torsion spring is preliminarily determined to be 80 degrees through calculation. However, in consideration of the error between the calculation and the actual model, a certain margin should be left for the installation of the torsion spring, so that when the structure of the manipulator finger is designed, an adjustable device needs to be designed to adjust the initial installation angle of the torsion spring within a certain range, so as to ensure a reliable and compact normally open state of the finger. Meanwhile, in order to ensure the gradual bending sequence of the knuckles when the object is grabbed, the rigidity of the torsion springs 15, 16 and 17 is increased in sequence.

The utility model relates to a three joint manipulator of pulley type underactuated's theory of operation as follows:

the wire rope is wound around three

drive wheels

10, 12, 14, and when the wire rope is pulled, friction is generated between the wire rope and the drive wheels, and rotational torque is generated on the

drive wheels

10, 12, 14. Because the spring 15 has small elastic force, and the spring force of the

springs

16 and 17 is large, the steel wire rope 6 is difficult to pull the second driving wheel 12 and the third driving wheel 14 to rotate around corresponding shafts at the beginning, so that the three knuckles 9-1, 9-2 and 9-3 are taken as a whole, and rotate around the base joint 8 against the constraint force of the spring 15 under the action of the first driving wheel 10, so as to realize the rotating action of the base joint; when the first knuckle 9-1 contacts an object, the first knuckle cannot rotate continuously, the tension of the steel wire rope 6 is increased, and the steel wire rope 6 pulls the second driving wheel 12 to overcome the restraining force of the second spring 16, so that the second knuckle 9-2 and the third knuckle 9-3 rotate around the proximal joint as a whole. When the second knuckle 9-2 contacts an object, the second knuckle cannot rotate continuously, the tension of the steel wire rope 6 is further increased, and the steel wire rope 6 pulls the third driving wheel 14 to overcome the restraining force of the third spring 17, so that the third knuckle 9-3 rotates around a far joint. And the robot stops until contacting an object, and finally realizes the rotation of the far joint and the grabbing and wrapping.

The utility model discloses an owe the actuating arm so can carry out bending motion through three fingers of a motor simultaneous drive, mainly rely on the principle of movable pulley, when movable pulley drives the movable pulley under the effect of tension and moves along the guide rail, the wire rope of cover on the movable pulley also follows the movable pulley and removes, if the atress of wire rope both sides is inhomogeneous, the movable pulley can also rotate around self axis. If the two ends of the steel wire rope are respectively fixed on the fingertips of two fingers, the steel wire rope can simultaneously drive the two fingers to move, and then if the two movable pulleys are connected in series, namely one output end of the first-stage movable pulley is directly connected with an under-actuated finger, and the other output end of the first-stage movable pulley is connected with the second-stage movable pulley, the two movable pulleys are connected in series, so that the three under-actuated fingers can be simultaneously driven to bend to move.

The above contents are only for explaining the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby, and any modification made on the basis of the technical solution according to the technical idea of the present invention all fall within the protection scope of the claims of the present invention.

Claims

1. The pulley type under-actuated three-joint manipulator is characterized by comprising three under-actuated fingers (9), wherein the three under-actuated fingers (9) are arranged on a supporting device at intervals, each under-actuated finger (9) has three degrees of freedom, a power system is arranged at the bottom of the supporting device, the power system is respectively connected with finger tips of the three under-actuated fingers (9) through a steel wire rope (6), and a differential mechanism is arranged between the steel wire rope (6) and the three under-actuated fingers (9).

2. The pulley type under-actuated three-joint manipulator as claimed in claim 1, wherein the power system comprises a transmission case (1), the transmission case (1) is connected with one side of a fixing plate (2) of the supporting device, the other side of the fixing plate (2) is connected with a retaining plate (7) through three guide rods (5), three base joints (8) are arranged on the retaining plate (7), and the three base joints (8) are correspondingly connected with three under-actuated fingers (9).

3. The pulley type under-actuated three-joint manipulator according to claim 2, wherein the differential mechanism comprises a first movable pulley (4-1) and a second movable pulley (4-2), the first slider (3-1) and the second slider (3-2) are respectively arranged on two adjacent guide rods (5), and the first movable pulley (4-1) and the second movable pulley (4-2) are correspondingly arranged on the first slider (3-1) and the second slider (3-2); one end of the steel wire rope (6) is connected with a steel wire shaft (19) arranged in the transmission case (1), and the other end of the steel wire rope is respectively connected with the fingertips of the three under-actuated fingers (9) through a first movable pulley (4-1) and a second movable pulley (4-2).

4. The pulley type under-actuated three-joint manipulator according to claim 3, wherein the steel wire rope (6) comprises a first steel wire rope (6-1), a second steel wire rope (6-2) and a third steel wire rope (6-3), one end of the first steel wire rope (6-1) is connected with a motor in the transmission case (1), and the other end of the first steel wire rope is fixed on the first sliding block (3-1); one end of a second steel wire rope (6-2) is connected with the fingertip of an under-actuated finger (9), and the other end of the second steel wire rope is connected with a second sliding block (3-2) through a first movable pulley (4-1); a third steel wire rope (6-3) is wound on the second movable pulley (4-2), and two ends of the third steel wire rope are respectively connected with the finger tips of the remaining two under-actuated fingers (9).

5. The pulley type under-actuated three-joint manipulator according to claim 1, wherein the under-actuated finger (9) comprises a first knuckle (9-1), a second knuckle (9-2) and a third knuckle (9-3), one end of the first knuckle (9-1) is connected with the base joint (8) through a shaft, the other end of the first knuckle is connected with one end of the second knuckle (9-2) through a shaft, and the other end of the second knuckle (9-2) is connected with one end of the third knuckle (9-3) through a shaft.

6. The pulley type under-actuated three-joint manipulator according to claim 5, wherein a first driving wheel (10) is arranged on a connecting shaft of the first knuckle (9-1) and the base joint (8), a second driving wheel (12) is arranged on a connecting shaft at the joint of the first knuckle (9-1) and the second knuckle (9-2), and a third driving wheel (14) is arranged on a connecting shaft at the joint of the second knuckle (9-2) and the third knuckle (9-3).

7. The pulley type under-actuated three-joint manipulator according to claim 5, wherein the first knuckle (9-1) is provided with a first fixed pulley (11), and the second knuckle (9-2) is provided with a second fixed pulley (13).

8. The pulley type under-actuated three-joint manipulator according to claim 5, wherein a first spring (15) is arranged between the first knuckle (9-1) and the base joint (8); a second spring (16) is arranged between the first knuckle (9-1) and the second knuckle (9-2); a third spring (17) is arranged between the second knuckle (9-2) and the third knuckle (9-3).

9. The pulley type under-actuated three-joint manipulator according to claim 1, wherein a stepping motor is arranged in the transmission case (1), the stepping motor is connected with a driving bevel gear (18) through a coupler, the driving bevel gear (18) is engaged with a driven bevel gear (22) sleeved on a steel wire shaft (19), and two ends of the steel wire shaft (19) are movably connected with a protective shell (21) through bearings (20).