CN111409096A

CN111409096A - Two-degree-of-freedom joint applied to dexterous robot hand

Info

Publication number: CN111409096A
Application number: CN201911018671.XA
Authority: CN
Inventors: 陶志成; 陈志培; 杨邦出; 葛涵; 朱李垚; 鲍官军
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2019-10-24
Filing date: 2019-10-24
Publication date: 2020-07-14
Anticipated expiration: 2039-10-24
Also published as: CN111409096B

Abstract

The invention discloses a two-degree-of-freedom joint applied to a dexterous robot hand, and aims to achieve two purposes, namely, solving the problem that the existing under-actuated mode is adopted for driving and has the defect of inflexibility, and the other purpose is to ensure that the moment arm in the motion process of the joint is constant and facilitate actual control. The invention comprises three knuckles which can rotate relatively and a rotating joint which is rotatably connected between the knuckles, wherein the rotating joint comprises a tendon rope fixing shaft, a rotating pulley and an auxiliary pulley are rotatably connected on the adjacent knuckle below the knuckle far away from the root of the dexterous hand, the outside of the rotating joint pulley and the auxiliary pulley is sleeved with a tendon rope, the tendon rope fixing shaft is provided with a through hole, the tendon rope passes through the through hole, and the diameter of the end part of the tendon rope is larger than that of the through hole. The dexterous hand is driven in a full-driving mode, and the maneuverability is good; the moment arm in the movement process of the joint is constant, so that the output quantity of the controller works in a reasonable interval.

Description

Two-degree-of-freedom joint applied to dexterous robot hand

Technical Field

The invention relates to the field of robots, in particular to the field of dexterous hands of robots.

Background

At present, the dexterous hand driven by the tendon mainly adopts an underactuated mode, namely a plurality of joints are driven by one driver. Although the underactuated driving mode has the advantage of reducing the number of drivers, a plurality of joints are driven by a single driver, so that certain coupling problem exists among the motions of the joints, and the dexterous degree of dexterous hands is reduced. If one actuator is provided for each joint, coupling problems between the joint and the joint motion may still be unavoidable. The coupling of the drives between the joints can lead to undesirable effects such as increased complexity and decreased accuracy of the control system, and even to movement of non-target joints.

Chinese patent publication No. CN109745157A, entitled "a multi-joint bionic dexterous tendon transmission artificial hand", which discloses a multi-joint bionic dexterous tendon transmission artificial hand, comprising a palm cavity, wherein a plurality of multi-joint bionic fingers are arranged on the palm cavity, a driven part is arranged in the palm cavity, and an active part which can be arranged on an arm and can drive the driven part to gradually advance by taking the relative rotation of the arm joint as power is arranged outside the palm cavity; the active part and the passive part are linked and drive the multi-joint bionic fingers through the tendon transmission part, so that all the multi-joint bionic fingers on the artificial hand are gradually closed or opened along with the gradual propulsion of the passive part. It adopts under-actuated mode to make combination, and the dexterous degree of dexterous hand is reduced.

Disclosure of Invention

The invention overcomes the problem that the prior dexterous hand is not flexible in driving by adopting an underactuated mode, provides a two-degree-of-freedom joint applied to the dexterous hand of a robot, and aims to realize a fully-driven dexterous hand with consistent moment arm, the dexterous hand is more flexible than the underactuated dexterous hand, the manipulator is fully driven and is not coupled, the moment arm in the movement process of the joint is ensured to be constant in the process, the actual control is convenient, the change relation between the displacement of a tendon rope and the angular displacement of the joint is a linear relation, the control difficulty is increased due to the nonlinear characteristic of a controlled object is reduced, and the output quantity of a controller is enabled to work in a reasonable interval.

In order to solve the technical problems, the invention adopts the following technical scheme:

the utility model provides a be applied to two degree of freedom joints of dexterous hand of robot, includes that the three section can relatively pivoted knuckle and rotate two rotation joints of connection between two liang of knuckles, rotate the joint include with keep away from the knuckle fixed axle that the knuckle of dexterous hand root is connected rotate on keeping away from the knuckle below adjacent knuckle of dexterous hand root and be connected with and rotate pulley and auxiliary pulley, the auxiliary pulley setting is in rotating the pulley below, the outside cover of rotating joint pulley and auxiliary pulley is equipped with the tendon rope, the tendon rope is fixed to be wound on rotating pulley and auxiliary pulley, is equipped with the through-hole on the tendon rope fixed axle, and the tendon rope passes through the through-hole, and the through-hole of tendon rope tip diameter is big.

Each joint of the scheme can be independently controlled, so that the scheme has better controllability, is more flexible than an underactuated driving mode, and can move more. For one joint, it is placed between two knuckles, the upper knuckle being hingedly connected to the lower knuckle. Specifically, the end part of the upper knuckle is provided with two through holes, the lower knuckle is also provided with two corresponding grooves, the end part of the upper knuckle is inserted into the lower knuckle and is connected through a rotating shaft, and a rotating pulley is sleeved and fixed on the rotating shaft in a gap between the two through holes. The same auxiliary pulley is also provided directly below the rotating pulley, and the circumferential surfaces of the two pulleys are on the same plane. The two ends of the outer edge of each pulley are high, the middle of the outer edge of each pulley is low, a groove for passing the wire is formed, the groove passes through the tendon rope, the tendon rope is wrapped on the two pulleys, the end parts of the tendon rope upwards extend into the wire through holes, the wire through holes are formed in the tendon rope fixing shafts, and the tendon rope fixing shafts are fixedly connected to the joints which rotate correspondingly. The fixed mode of tendon rope can be for its tip knot make its direct grow, also can overlap the shrink that this structure of diameter ratio passed through the tendon rope and realize corresponding articular rotation, and simultaneously, the both ends of tendon rope set up on rotating the pulley, and in the finger motion process, the tendon rope remains unchanged for finger joint's arm of force all the time, can not change for finger joint angle's change. Without the tendon rope securing axle, the rotating pulley would be subjected to a considerable load and would have a short life.

Preferably, the rotating pulley and the auxiliary pulley are fixedly sleeved on a rotating shaft, and the rotating shaft is rotatably connected to the knuckle. The rotating shaft and the corresponding pulley are connected through a key or the shaft body is in an asymmetric shape, and the pulley core part is provided with a groove corresponding to the pulley.

Preferably, the rotating shaft of the rotating joint far away from the fingertip and the fixed shaft of the tendon rope are provided with thread through holes for passing the tendon rope, and the tendon rope passes through the thread through holes and is wound and fixed on the rotating pulley and the auxiliary pulley of the rotating joint near the fingertip. The lower rotating shaft and the tendon rope fixing shaft are provided with wire through holes which are used for realizing the basis of static decoupling through the tendon ropes of the upper rotating joint.

Preferably, an avoiding groove is arranged at the position of the line passing hole on a rotating shaft of the rotating joint far away from the fingertip, the avoiding groove is arranged in the rotating direction of the fingertip, an angle bending section used for reducing friction of the tendon rope is arranged at the joint of the avoiding groove and the line passing hole, and the avoiding groove enables the tendon rope to still pass through the axis of the rotating shaft when the tendon rope is bent. If the avoidance groove is not arranged, when the lower joint rotates, the tendon rope inevitably interferes with the rotating shaft, and the deflection center of the tendon rope is the friction part with the rotating shaft and is not the shaft center of the rotating shaft any more, so that coupling is caused. One end of the avoiding groove is arranged on the wire passing hole, the other end of the avoiding groove penetrates through the rotating shaft, and a bent section formed by the avoiding groove and the rotating shaft is easily contacted by the tendon rope, so that an outwards convex bent angle section is arranged. The angled sections may reduce friction and stress on the tendon rope. The avoiding groove can avoid friction between the tendon rope and the outer edge of the end part of the hole of the wire passing hole, and can ensure that the tendon rope can still pass through the axis of the rotating shaft when being bent, so that decoupling is realized.

Preferably, a rotating pulley of the rotating joint far away from the fingertip is connected with a shaft sleeve used for positioning, the shaft sleeve is provided with a line passing hole and an avoiding groove used for passing the tendon rope, the avoiding groove is arranged in the rotating direction of the fingertip along the circumferential direction of the shaft sleeve, one end, far away from the line passing hole, of the avoiding groove is provided with an angle bending end used for reducing friction of the tendon rope, and the avoiding groove enables the tendon rope to still pass through the shaft sleeve axis when the tendon rope is bent. The purpose of the avoiding groove is consistent with that of the avoiding groove on the rotating shaft, the avoiding groove is arranged along the circumferential direction of the shaft sleeve in order to realize dynamic coupling, and one end of the avoiding groove is arranged on the wire passing hole.

Preferably, an axial gap is provided between the shaft and the knuckle. This axial clearance can be used to prevent interference between the shaft and the joint due to contact, and to improve the reliability of the machine. The axial gap can be further enlarged to add a hall sensor or a rotary rheostat to achieve feedback of angular displacement.

Preferably, the tendon ropes include driving and restoring tendon ropes wrapped on both sides of the auxiliary pulley and wrapped on the rotating pulley from the other direction, the tendon ropes passing through the through-hole of the corresponding tendon rope fixing shaft. The driving tendon rope and the restoring tendon rope are wrapped on the two pulleys in an 8-shaped manner, the wrapping directions of the two tendon ropes are opposite, and the two groups of pulleys are adopted to form a larger wrap angle on the rotating pulleys so as to prevent the tendon ropes from sliding out of the pulleys in the movement process.

Preferably, the two ends of the rotating shaft are thin and the middle is thick, and a bearing is arranged between the rotating shaft and the knuckle. The bearing inner ring is fixedly connected with the rotating shaft, and the rotating shaft rotates relative to the knuckle through interference fit of the outer ring and the knuckle below the outer ring.

Preferably, the two revolute joints are spaced apart. The tendon rope wound by the upper rotary joint is bent only in one plane, so that the tendon rope can be better ensured to pass through the axis of the lower rotary shaft during bending, and the force arms are ensured to be consistent.

Compared with the prior art, the invention has the beneficial effects that: (1) the dexterous hand is driven in a full-driving mode, so that the dexterous hand is more flexible and has better maneuverability; (2) the moment arm in the movement process of the joint is constant, so that the actual control is facilitated, the change relation between the displacement of the tendon rope and the angular displacement of the joint is a linear relation, the control difficulty is increased due to the nonlinear characteristic of a controlled object is reduced, and the output quantity of the controller works in a reasonable interval; (3) the coupling-free motion of each joint of the fingers is realized while the full drive of the fingers is realized, so that the single joint can be independently controlled.

Drawings

FIG. 1 is a partial cross-sectional view of a finger of the present invention;

FIG. 2 is an enlarged view taken at line A-A of FIG. 1;

FIG. 3 is an enlarged view taken at FIG. 1B-B;

FIG. 4 is a perspective view of the rotating shaft of the present invention;

FIG. 5 is a partial cross-sectional view of the present invention taken in a vertical direction relative to FIG. 1;

FIG. 6 is a perspective view of the rotating pulley of the present invention;

in the figure: the tendon rope comprises a knuckle 1, a rotary joint 2, a groove 3, a tendon rope fixing shaft 4, a rotary pulley 5, a rotary shaft 6, an auxiliary pulley 7, an auxiliary rotary shaft 8, a bearing 9, a tendon rope 10, a wire through hole 11, a wire through hole 12, a driving tendon rope 13, a restoring tendon rope 14, an avoiding groove 15, a limiting plate 16, a bend section 17 and a shaft sleeve 18.

Detailed Description

The technical scheme of the invention is further described in detail by the following specific embodiments in combination with the attached drawings:

example (b):

a two-degree-of-freedom joint applied to a dexterous robot hand is shown in figure 1 and comprises three finger joints 1 capable of rotating relatively and two rotating joints 2 rotatably connected between every two finger joints 1, wherein each finger joint 1 is formed by combining two symmetrical components, and the two components are fixedly connected with corresponding screws through three fixing holes formed in the two components. The hinged joint between the upper knuckle 1 and the lower knuckle 1 of two connected knuckles 1 is provided with two oppositely arranged grooves 3, the two grooves 3 are used for reducing the contact area between the two knuckles 1 and reducing the friction force, and meanwhile, the two grooves 3 can store lubricating oil and reduce the abrasion. As shown in figures 2 and 3, the rotary joint 2 comprises a tendon rope fixing shaft 4 connected with a knuckle 1 far away from the root of the dexterous hand, a rotary pulley 5 and an auxiliary pulley 7 are rotatably connected on the adjacent knuckle 1 below the knuckle 1 far away from the root of the dexterous hand, and the end surfaces of the rotary pulley and the auxiliary pulley protrude in the circumferential direction to form a wire groove which prevents the tendon rope from falling off. The tendon rope fixing shaft and the knuckle above the tendon rope fixing shaft are integrally formed. The rotating pulley 5 and the auxiliary pulley 7 are fixedly sleeved on a rotating shaft, the rotating shaft where the rotating pulley 5 is located is a rotating shaft 6, the rotating shaft where the auxiliary pulley 7 is located is an auxiliary rotating shaft 8, and the rotating shafts are rotatably connected to the knuckle 1. The two ends of the rotating shaft 6 are thin and the middle is thick, and a bearing 9 is arranged between the rotating shaft and the knuckle 1. The inner ring of the bearing 9 is fixedly connected with the rotating shaft, and the outer ring is in interference fit with the knuckle 1 below to realize the rotation of the rotating shaft relative to the knuckle 1. The rotating shaft and the corresponding pulley are connected through a key or the shaft body is in an asymmetric shape, and the pulley core part is provided with a groove corresponding to the pulley.

The auxiliary pulley 7 is arranged below the rotating pulley 5, the outer sides of the pulley of the rotating joint 2 and the auxiliary pulley 7 are sleeved with the tendon rope 10, the tendon rope 10 is fixedly wound on the rotating pulley 5 and the auxiliary pulley 7, the tendon rope fixing shaft 4 is provided with a through hole 11, the tendon rope 10 passes through the through hole 11, and the diameter of the end part of the tendon rope 10 is larger than that of the through hole 11. As shown in fig. 3, the rotating shaft of the rotating joint 2 far away from the fingertip and the tendon rope fixing shaft 4 are provided with thread passing holes 12 for passing the tendon ropes 10, and the tendon ropes 10 are wound and fixed on the rotating pulley 5 and the auxiliary pulley 7 of the rotating joint 2 near the fingertip through the thread passing holes 11. The lower spindle and tendon string fixing shaft 4 has a through thread hole 12 for static decoupling by the tendon string 10 of the upper revolute joint 2. As shown in fig. 5, the tendon string 10 includes a driving tendon string 13 and a returning tendon string 14, the driving tendon string 13 and the returning tendon string 14 being wrapped on both sides of the auxiliary pulley 7 and on the rotating pulley 5 from the other direction, the tendon string 10 passing through the through-hole 11 of the corresponding tendon string fixing shaft 4. The driving tendon rope 13 and the restoring tendon rope 14 are wrapped on the two pulleys in an 8 shape, the wrapping directions of the two tendon ropes 10 are opposite, and the two groups of pulleys are used for forming a larger wrapping angle on the rotating pulley 5 and preventing the tendon ropes 10 from sliding out of the pulleys in the movement process.

As shown in fig. 4, an avoiding groove is arranged at the position of the line passing hole on the rotating shaft of the rotating joint far away from the fingertip, the avoiding groove is arranged in the rotating direction of the fingertip, a bent angle section 17 for reducing friction of the tendon rope is arranged at the joint of the avoiding groove and the line passing hole, and the avoiding groove enables the tendon rope to still pass through the axis of the rotating shaft when the tendon rope is bent. If the avoidance groove is not arranged, when the lower joint rotates, the tendon rope inevitably interferes with the avoidance groove, and the deflection center of the tendon rope is the friction part between the tendon rope and the rotating shaft and is not the shaft center of the rotating shaft any more, so that coupling is caused. One end of the avoiding groove is arranged on the wire passing hole, the other end of the avoiding groove penetrates through the rotating shaft, and the bending section 17 formed by the avoiding groove and the rotating shaft is easily contacted by the tendon rope, so that the bending section 17 protruding outwards is arranged. The angled sections may reduce friction and stress on the tendon rope. The avoiding groove can avoid friction between the tendon rope and the outer edge of the end part of the hole of the wire passing hole, and can ensure that the tendon rope can still pass through the axis of the rotating shaft to cause coupling when being bent. As shown in fig. 6, a shaft sleeve 18 for positioning is connected to a rotating pulley of a rotating joint far away from a fingertip, a line passing hole 12 for passing a tendon rope and an avoiding groove 15 are arranged on the shaft sleeve 18, the avoiding groove 15 is arranged in the rotating direction of the fingertip along the circumferential direction of the shaft sleeve 18, a bent angle end 17 for reducing friction of the tendon rope is arranged at one end of the avoiding groove far away from the line passing hole, and the avoiding groove enables the tendon rope to still pass through the shaft sleeve axis when being bent. The purpose of the avoiding groove is consistent with that of the avoiding groove on the rotating shaft, the avoiding groove is arranged along the circumferential direction of the shaft sleeve in order to realize dynamic coupling, and one end of the avoiding groove is arranged on the wire passing hole.

An axial clearance is arranged between the rotating shaft and the knuckle 1. This axial clearance can be used to prevent interference between the shaft and the joint due to contact, and to improve the reliability of the machine. The axial gap can be further enlarged to add a hall sensor or a rotary rheostat to achieve feedback of angular displacement. The pulley shaft is connected with a shaft sleeve, the shaft sleeve is connected to the rotating shaft, and the wire passing hole passes through the shaft sleeve, so that the shaft sleeve is also provided with a corresponding hole and an avoiding groove. The two revolute joints 2 are arranged at intervals. The tendon rope 10 wound by the upper rotary joint 2 is bent only in one plane, so that the tendon rope 10 can be better ensured to pass through the axis of the lower rotary shaft when being bent, and the force arms are ensured to be consistent. The knuckle 1 distant from the fingertip is called a proximal end, and has, below the corresponding revolute joint 2, stopper plates 16 for stopping the tendon strings 10 connected to the two revolute joints 2, respectively, and the stopper plates 16 have two holes for passing through the different revolute joints 2, respectively. Two ends of the rotating pulley 5 and the auxiliary pulley 7 extend out to form a wire groove for avoiding wire falling.

Each joint of the scheme can be independently controlled, so that the scheme has better controllability, is more flexible than an underactuated driving mode, and can move more. For one joint, it is placed between two knuckles, the upper knuckle being hingedly connected to the lower knuckle. Specifically, the end part of the upper knuckle is provided with two through holes, the lower knuckle is also provided with two corresponding grooves, the end part of the upper knuckle is inserted into the lower knuckle and is connected through a rotating shaft, and a rotating pulley is sleeved and fixed on the rotating shaft in a gap between the two through holes. The same auxiliary pulley is also provided directly below the rotating pulley, and the circumferential surfaces of the two pulleys are on the same plane. The two ends of the outer edge of each pulley are high, the middle of the outer edge of each pulley is low, a groove for passing the wire is formed, the groove passes through the tendon rope, the tendon rope is wrapped on the two pulleys, the end parts of the tendon rope upwards extend into the wire through holes, the wire through holes are formed in the tendon rope fixing shafts, and the tendon rope fixing shafts are fixedly connected to the joints which rotate correspondingly. The fixed mode of tendon rope can be for its tip knot make its direct grow, also can overlap the diameter ratio and this structure realizes corresponding articular rotation through the shrink of tendon rope, and simultaneously, the both ends of tendon rope set up on rotating the pulley, and the arm of force is unanimous, and the power of reply and drive is unanimous. Without the tendon rope securing axle, the rotating pulley would be subjected to a considerable load and would have a short life.

The above-described embodiments are merely preferred embodiments of the present invention, which is not intended to be limiting in any way, and other variations and modifications are possible without departing from the scope of the invention as set forth in the appended claims.

Claims

1. The utility model provides a be applied to two degree of freedom joints of dexterous hand of robot, includes that the three section can relatively pivoted knuckle and rotate two rotation joints of connection between two liang of knuckles, its characterized in that, rotate the joint include with keep away from the knuckle fixed axle that the knuckle of dexterous hand root is connected rotate the rotation pulley and the supplementary pulley of connection on keeping away from the knuckle below adjacent knuckle of dexterous hand root, supplementary pulley sets up in rotating the pulley below, and the outside cover of rotating joint pulley and supplementary pulley is equipped with the tendon rope, and the tendon rope is fixed to be wound on rotating pulley and supplementary pulley, is equipped with the through-hole on the tendon rope fixed axle, and the tendon rope passes through the through-hole, and the diameter of tendon rope tip is bigger than the through-hole.

2. The two-degree-of-freedom joint applied to the dexterous robot hand of claim 1, wherein the rotating pulley and the auxiliary pulley are fixedly sleeved on a rotating shaft, and the rotating shaft is rotatably connected to a knuckle.

3. The two-degree-of-freedom joint applied to the dexterous robot hand of claim 2, wherein the rotating shaft of the rotating joint far away from the fingertip and the fixing shaft of the tendon rope are provided with wire through holes for passing the tendon rope, and the tendon rope is wound and fixed on the rotating pulley and the auxiliary pulley of the rotating joint close to the fingertip through the wire through holes.

4. The two-degree-of-freedom joint applied to the dexterous hand of the robot as claimed in claim 3, wherein an avoiding groove is arranged at the position of the line passing hole on the rotating shaft of the rotating joint far away from the fingertip, the avoiding groove is arranged in the rotating direction of the fingertip, an angle bending section for reducing friction of the tendon rope is arranged at the joint of the avoiding groove and the line passing hole, and the avoiding groove enables the tendon rope to still pass through the axis of the rotating shaft when being bent.

5. The two-degree-of-freedom joint applied to the dexterous robot hand as claimed in claim 4, wherein the rotating pulley of the rotating joint far away from the fingertip is connected with a shaft sleeve for positioning, the shaft sleeve is provided with a line passing hole and an avoiding groove for passing the tendon rope, the avoiding groove is arranged in the rotating direction of the fingertip along the circumferential direction of the shaft sleeve, one end of the avoiding groove far away from the line passing hole is provided with an angle bending end for reducing the friction of the tendon rope, and the avoiding groove enables the tendon rope to still pass through the shaft sleeve axis when being bent.

6. The two-degree-of-freedom joint for a dexterous robot hand of claim 2, wherein an axial gap is provided between the shaft and the knuckle.

7. The two-degree-of-freedom joint applied to a dexterous robot hand of claim 1, wherein the tendon rope comprises a driving tendon rope and a restoring tendon rope, which are wrapped on both sides of the auxiliary pulley and wrapped on the rotating pulley from the other direction, and which pass through the through-hole of the fixing shaft of the corresponding tendon rope.

8. The two-degree-of-freedom joint applied to the dexterous hand of the robot as claimed in claim 2, wherein the two ends of the rotating shaft are thin and the middle is thick, and a bearing is arranged between the rotating shaft and the knuckle.

9. A two degree of freedom joint for a robotic dexterous hand according to any of claims 1 to 8, wherein the two revolute joints are spaced apart.