CN110053064A - A kind of flexible cable traction finger manipulator of drive lacking four with elastic joint - Google Patents

Abstract

The invention discloses a flexible cable traction underactuated four-finger manipulator with elastic joints, which comprises an underactuated finger part, an installation base part and a power drive part, and the underactuated finger part is connected with the power drive part through the installation base part; The manipulator is mounted on the end of the manipulator or the fixed base through the mounting base part. The four underactuated fingers of the present invention are distributed side by side, and a set of drivers simultaneously drives the two side by side underactuated fingers. The structure is simple, reliable, small in size, and light in weight; due to the elastic joints, the shape and size of the grasped object have a good effect. Strong adaptability, reduces the difficulty of control when grasping objects, reduces the requirements of the device on the control system, realizes less driver to drive more degrees of freedom of finger joints, and has the ability to grasp objects of different shapes and sizes. Self-adaptive; and fingers formed by two knuckles can be used to form two-knuckle underactuated fingers, which realizes the modularization of fingers to a certain extent.

Description

An underactuated four-finger manipulator with flexible cable traction with elastic joints

technical field

The invention belongs to the technical field of robotics, in particular to a four-fingered manipulator with elastic joints for traction under-actuated by a flexible cable.

technical background

Similar to human, the hand structure is an important part of the robot humanoid actuator. In order to increase the humanoidization of the hand, the hand should be designed with more joint degrees of freedom; however, in order to reduce the difficulty of control, reduce the volume of the hand , weight, and the need to reduce the number of drives, there is a certain contradiction between the two; in addition, in order to better grasp the object, it is also necessary for the fingers to have a certain degree of adaptability when grasping the object. An existing self-adaptive underactuated manipulator device, such as the United States invention patent US5762390, has the disadvantage that the motor, pulley transmission mechanism and screw transmission mechanism of the device are not only complicated in device, but also heavier and bulkier. It is too large and cannot be installed in the finger knuckles, but can only be installed in the palm base, resulting in a large volume of the palm base; the multiple four-bar linkage mechanisms that realize the sequential rotation of the finger knuckles are complicated and have high manufacturing costs; it is not suitable for installation in industrial used on the robot. An existing self-adaptive underactuated mechanical finger device, such as Chinese invention patent CN1365875A, includes a first knuckle, an active plate, a second knuckle, and an underactuated joint. The disadvantage of this device is that the device adopts multi-stage gear transmission, which is a gear box at the joint, and the volume is large: the active plate rotates, so that the end away from the joint is too far from the surface of the first knuckle, As a result, one end of the finger is much thicker than the other end, which is quite different from the human hand; although the device is basically feasible to imitate the thumb, it is not suitable for imitating other fingers except the thumb. , ring finger and little finger, the appearance will be too different from the human hand.

Therefore, the present invention designs a four-fingered manipulator with flexible cable traction underactuated with elastic joints, which can better realize more joint degrees of freedom, less number of drivers, and stronger performance when grasping objects of different shapes and sizes. Adaptability to these three goals.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies in the prior art, and propose a four-fingered manipulator with flexible cable traction under-actuated with elastic joints. Driving a four-finger manipulator, the device is simple in structure, small in size and low in cost. It is used to achieve more degrees of freedom of finger joints driven by fewer drivers. It has good grasping performance and certain operating performance, and has good research and Value.

The concrete structure of the present invention is as follows:

A flexible cable traction underactuated four-finger manipulator with elastic joints is characterized in that: it comprises an underactuated finger part, an installation base part and a power drive part, and the underactuated finger part is connected with the power drive part through the installation base part;

The underactuated finger part includes four underactuated fingers with the same structure, and the underactuated fingers include end knuckles, middle knuckles, proximal knuckles, and two elastic body joints, and the two elastic body joints have two ends. They are embedded between the end knuckles, the middle knuckles and between the middle knuckles and the proximal knuckles respectively; the end knuckles include the end knuckle inner plate, the end knuckle outer plate and the end knuckle friction rubber pad , the inner plate of the end phalanx and the outer plate of the end phalanx are wedged together through the dovetail groove, and the friction-increasing rubber pad of the end phalanx is embedded in the T-shaped groove opened on the inner side of the inner plate of the end phalanx; the middle phalanx includes the middle phalanx The inner plate, the outer plate of the middle phalanx and the rubber pad for increasing the friction of the middle phalanx, the inner plate of the middle phalanx and the outer plate of the middle phalanx are wedged by the dovetail groove, and the rubber pad of increasing the friction of the middle phalanx is embedded in the inner side of the inner plate of the middle phalanx. In the T-shaped groove of Through dovetail groove wedging, the proximal phalanx friction-increasing rubber pads are embedded in the T-shaped grooves on the inner side of the proximal phalanx inner plate; each friction-increasing rubber pad covers the surface of each phalanx inner plate, so that on the one hand, the finger surface and the object The soft finger surface contact between them increases the degree of restraint of the fingers on the object, and on the other hand, it can also increase the friction force, thereby improving the stability of grasping the object;

The power drive part is used for power supply in the whole grasping process of the manipulator, including a stepping motor, a coupling, a traction cable winding wheel and a motor synchronously driving the rotating shaft;

The installation base part includes an upper panel of the base, a left panel of the base, and a right panel of the base. The upper panel of the base is installed on the left panel of the base and the right panel of the base. The upper panel of the base is provided with four Underactuated finger connection seat, four underactuated finger connection seat are used to connect four identical underactuated fingers, four underactuated finger connection seat are symmetrically arranged in two pairs, underactuated finger connection seat includes double-ended stud, miniature guide wheel, A pair of L-shaped fixed lugs and a rectangular hole for flexible cable traction, the pair of L-shaped fixed lugs are fixed back-to-back on the upper side panel of the base with bolts, and the stud bolts are fixed on a pair of L-shaped fixed lugs through nuts , the miniature guide wheel is sleeved on the stud bolt and is located between the two L-shaped fixed lugs, and the upper side panel of the base located between the two L-shaped lugs is provided with a rectangular hole for pulling a flexible cable; the proximal knuckle rotates Installed on the stud; two miniature bearings are symmetrically installed on the right panel of the base and the left panel of the base, and two pairs of miniature bearings are fixed between two motors to drive the shaft synchronously, and two traction flex cable reels The fixed sleeve is mounted on the two motor synchronous driving shafts, the two stepping motors are respectively connected with the corresponding motor synchronous driving shafts through the coupling, and the two stepping motors are installed on the right panel of the base through the motor mounting bracket;

The inner and outer plates of the end, middle and proximal phalanx of the underactuated fingers are all provided with small holes, one end of the flexible cable of each underactuated finger is fixed on the end phalanx, and the other end passes through the end, middle and proximal ends The small holes on the inner and outer plates of the knuckles and the rectangular holes for cable traction are fixed on the corresponding traction cable reels.

The described under-actuated four-finger manipulator with flexible cable traction with elastic joints is characterized in that: the diameter of the double-ended stud is 5 mm, and the proximal phalanx of the under-actuated finger passes through the proximal phalanx inner plate, The circular through holes formed by the semicircular through holes symmetrically opened on the outer plate of the proximal phalanx are rotatably mounted on the stud bolts, and the traction cable winding wheel is located in the middle of the proximal phalanx.

The flexible cable traction under-actuated four-finger manipulator with elastic joints is characterized in that: the traction flexible cable winding wheel is in the form of thin middle and thick ends, the central cylindrical hole is used to place the motor synchronously driven rotating shaft, and the two There are positioning threaded holes on the head of the cylinder with the thicker end for fixing the synchronous driving shaft of the motor, so that the traction cable reel and the synchronous driving shaft of the motor rotate at the same time without deviation. There is a spiral groove, which can limit the flexible cable in the groove to prevent falling off and dislocation.

The flexible cable traction under-actuated four-finger manipulator with elastic joints is characterized in that: the inner diameter of the miniature bearing is 6mm and the outer diameter is 15mm, and each miniature bearing is respectively embedded in the left panel of the base and the right panel of the base , The inner ring of the miniature bearing is matched with the synchronous drive shaft of the motor.

The described four-finger manipulator with flexible cable traction underactuated with elastic joints is characterized in that: the left side panel of the base and the right side panel of the base are provided with threaded holes for connecting the upper side panel of the base, and the bottoms are provided with threaded holes. There are countersunk sockets for anchor screws, which are used to fix the manipulator on the base.

The flexible cable traction under-actuated four-finger manipulator with elastic joints is characterized in that the flexible cable is a steel wire rope with a diameter of 0.45 mm.

The underactuated four-fingered manipulator with flexible cable traction with elastic joints is characterized in that: the end, middle and proximal knuckles of the underactuated fingers are made of PLA material, which can be processed by 3D printing, to a greater extent. At the same time, due to the lubricating effect of the PLA material, the bearings between the proximal knuckles, studs and L-shaped fixed lugs are omitted.

The described four-fingered manipulator with flexible cable traction under-actuated with elastic joints is characterized in that: the elastic joints are made of elastic rubber material, which can provide restoring force when the release action is performed.

The described underactuated four-fingered manipulator with flexible cable traction with elastic joints is characterized in that: the underactuated fingers can also be composed of end knuckles and proximal knuckles to form two knuckle underactuated fingers, so as to complete a smaller-diameter underactuated finger. Grasping of objects.

The present invention has the following advantages and outstanding effects:

The four underactuated fingers of the present invention are arranged side by side, and one set of drivers simultaneously drives two side by side underactuated fingers. The structure is simple, reliable, small in size, and light in weight; due to the elastic joints, the shape and size of the grasped object have a good effect. Strong adaptability, reduces the difficulty of control when grasping objects, reduces the requirements of the device on the control system, realizes less driver to drive more degrees of freedom of finger joints, and has the ability to grasp objects of different shapes and sizes. Self-adaptive; and two-phalangeal underactuated hands can be formed by using fingers formed by two knuckles, realizing finger modularization to a certain extent.

Description of drawings

Fig. 1 is the overall structure diagram of the underactuated four-finger manipulator with flexible cable traction;

Figure 2 is an intuitive view of the finger;

Figure 3 is a schematic diagram of each part of the finger composition;

Figure 4(a) is a perspective view of the outer plate of the terminal knuckle;

Figure 4(b) is a schematic front view of the outer plate of the terminal knuckle;

Figure 4(c) is a schematic bottom view of the outer plate of the distal knuckle;

Figure 5(a) is a perspective view of the inner plate of the distal knuckle;

Figure 5(b) is a schematic front view of the inner plate of the end knuckle;

Figure 5(c) is a schematic bottom view of the inner plate of the distal knuckle;

Figure 6 is a schematic diagram of an interphalangeal elastic body joint;

Fig. 7 is the schematic diagram of the base part;

Figure 8 is a schematic diagram of the components of the base top plate;

Figure 9 is a schematic diagram of each part of the right side plate of the base;

Figure 10 is a schematic diagram of each part of the left side plate of the base;

Figure 11 is a schematic diagram of the structure of the winding wheel;

Figure 12 is a schematic diagram of a two-knuckle finger;

Figure 13 is a schematic diagram of each part of the drive components.

Detailed ways

The specific embodiments of the underactuated four-fingered manipulator with flexible cable traction with elastic joints of the present invention are given below, and described with reference to the accompanying drawings.

As shown in FIG. 1 , a specific implementation of the present invention provides an underactuated four-finger manipulator with elastic joints for cable traction, including an underactuated finger part 1 , a mounting base part 2 and a power drive part 3 . The underactuated finger part 1 is connected to the power drive part 3 through the mounting base part 2, and the manipulator is installed on the end of the manipulator or the fixed base through the mounting base part, and is applied to the grasping execution device at the end of different industrial robots.

The structure of the underactuated finger portion 1 is shown in Figures 2 and 3. The underactuated finger portion includes four underactuated fingers with the same structure, and the underactuated fingers include end knuckles, middle knuckles, proximal knuckles, and two underactuated fingers. two elastic body joints 1401, the two ends of the two elastic body joints 1401 are respectively embedded between the end knuckles, the middle knuckles and between the middle knuckles and the proximal knuckles; as shown in Figures 4 and 5, the end knuckles include End knuckle inner plate 1102, end knuckle outer plate 1103 and end knuckle friction increasing rubber pad 1101, end knuckle inner plate 1102 and end knuckle outer plate 1103 are wedged by dovetail groove, end knuckle friction increasing rubber pad 1101 The middle phalanx includes the middle phalanx inner plate 1202, the middle phalanx outer plate 1203, the middle phalanx friction-increasing rubber pad 1201, the middle phalanx inner plate 1202 and The outer plate 1203 of the middle phalanx is wedged together by a dovetail groove, and the friction-increasing rubber pad 1201 of the middle phalanx is embedded in the T-shaped groove opened on the inner side of the inner plate 1202 of the middle phalanx; the proximal phalanx includes the inner plate 1302 of the proximal phalanx, the The end phalanx outer plate 1303 and the proximal phalanx friction-increasing rubber pad 1301, the proximal phalanx inner plate 1302 and the proximal phalanx outer plate 1303 are wedged through a dovetail groove, and the proximal phalanx friction-increasing rubber pad 1301 is embedded in the proximal end In the T-shaped grooves opened on the inner side of the knuckle plate 1302; each friction-increasing rubber pad covers the surface of each knuckle inner plate, so that on the one hand, the soft finger surface contact between the finger surface and the object increases the degree of restraint of the finger on the object, On the other hand, it can also increase the friction force, thereby improving the stability of grasping objects;

As shown in FIG. 6 , the elastic body joint 1401 is designed with convex bodies at the left and right ends to cooperate with the proximal knuckle, the middle knuckle and the end knuckle, which can prevent the elastic joint 1401 from being in the finger knuckles during operation. Rotation, there is a rectangular hole next to the convex body, which is convenient for the connection between the two, and can make the elastic body joint 1401 and the knuckle width consistent, maintain the integrity of the appearance of the finger, and use the T-shaped groove to prevent the left and right direction of the knuckle. When the underactuated fingers are installed, the end knuckle friction increasing rubber pad 1101, the middle knuckle friction increasing rubber pad 1201, and the proximal knuckle friction increasing rubber pad 1301 are respectively installed on the three knuckles through the T-slot, and the elastic The body joint 1401 is nested on the head end of the proximal phalanx and the end of the distal phalanx. The outer plate 1103 of the distal phalanx and the outer plate 1302 of the proximal phalanx are respectively connected with the inner plate 1102 of the distal phalanx and the inner plate of the proximal phalanx. The dovetail grooves on the 1302 are matched to fix one end of the elastomer joint 1401, and then the unconnected ends are respectively sleeved on both ends of the middle phalanx inner plate 1202, and the middle phalanx outer plate 1203 and the middle phalanx inner plate 1202 are passed through the dovetail groove. Mate to complete the underactuated finger assembly.

The installation base part 2 is mainly used to realize the connection between the underactuated finger part 1 and the power drive part 3, and can be fixed on the base. Its structure is shown in Figure 7, including the upper side panel of the base, the left panel of the base, and the right side of the base Panel, as shown in FIG. 8 , the upper side panel of the base includes an upper side panel 2105, and the upper side panel 2105 is provided with four underactuated finger connection seats, and the four underactuated finger connection seats are used to connect four identical underactuated fingers. Finger 1, the four underactuated finger connecting bases are symmetrically arranged in pairs, the underactuated finger connecting bases include double-ended studs 2101, miniature guide wheels 2102, a pair of L-shaped fixing lugs 2103, flexible cable traction rectangular holes 2104, and the upper side Panel 2105, two L-shaped fixed lugs 2103 are fixed on the upper side panel 2105 with bolts, the underactuated finger part 1 is placed between the left and right L-shaped fixed lugs 2103, and the miniature guide wheels 2102 are aligned close to The through hole at the end of the end knuckle is placed in the middle, the double-ended stud 2101 passes through the through hole in turn, the two ends of the double-ended stud 2101 are fixed with nuts, and are located on the upper panel 2105 between the two L-shaped ear seats 2103 There is a rectangular hole 2104 for cable traction; the right side panel of the base is mainly used to install the stepper motor 3004 and the fixed traction cable winding wheel 3001. Its structure is shown in Figure 9, including the motor mounting bracket 2201 and the right side panel. 2202, miniature bearing 2203, the motor mounting bracket 2201 is connected to the stepper motor 3004 through four bolts, the right side panel 2202 and the motor mounting bracket 2201 are fixed with the same specification bolts, the left side panel of the base is used to resist traction The other end of the cable reel 3001, as shown in Figure 10, includes a left side panel 2301 and a miniature bearing 2302. The left side panel 2301 and the right side panel 2202 have threaded holes for connecting the upper side panel 2105 , there are anchor screw countersunk seats under it, which are used to fix the manipulator on the base, the inner countersunk seats are respectively embedded in the miniature bearing 2302 and the miniature bearing 2203, the outer ring of the miniature bearing 2302 is fixed, and the inner ring of the bearing is One end of the motor synchronous driving shaft 3002 is matched, and the inner ring of the micro bearing 2203 is matched with the other end of the motor synchronous driving shaft 3002.

The power drive part 3 is mainly used for the power supply in the whole manipulator grasping process. 3002, the stepper motor 3004 and the motor mounting bracket 2201 are fixed with bolts.

The structure of the traction cable reel 3001 is shown in FIG. 11 , the two ends are symmetrically distributed, and the central cylindrical hole is used to place the motor synchronous drive shaft 3002. The traction cable reel 3001 is designed to be thin in the middle and thick at both ends. In the form, there are positioning threaded holes on the head of the thick cylinder at both ends to fix the motor synchronous drive shaft 3002, so that the traction cable reel 3001 and the motor synchronous drive shaft 3002 rotate at the same time without offset, and the traction is flexible. There are spiral grooves at both ends of the thin cylinder between the cable winding wheels 3001, which can restrict the flexible cable in the grooves to prevent falling off and dislocation. The motor synchronous driving shaft 3002 is installed between the left side panel 2301 and the right side panel 2202 through the micro bearing 2203 and the micro bearing 2302. The coupling 3003 is connected to the stepping motor 3004 and the motor synchronous driving shaft 3002 and performs synchronous transmission .

The flexible cable-driven under-actuated four-finger manipulator with elastic joints of the present invention works as follows:

When the manipulator grabs the object, after the optimization calculation is carried out for the specific object to be grabbed, the stretching length range of the wire rope is designed, and the grabbing posture and contact point position corresponding to the required grasping force can be calculated. The point position is controlled precisely and cooperatively by the rotation angle of the two traction cable reels 3001 and the stepping motor 3004, so as to achieve both degree of freedom adaptability, non-destructive and reliable grasping of various types of complex objects.

When the manipulator is stationary, the underactuated fingers remain in a hovering state; when the four-finger manipulator works, the stepping motor 3004 is programmed to rotate forward, and the rotation is transmitted to the motor synchronously to drive the shaft 3002 through the coupling 3003, and the motor The synchronous drive shaft 3002 and the traction cable reel 3001 are locked by screws to realize synchronous rotation of the two. In this embodiment, a traction cable reel 3001 drives two underactuated fingers to bend at the same time, and all the knuckles in the underactuated finger 1 adopt a modular design, which can be easily disassembled and assembled. Adding friction-increasing rubber pads can increase friction at the same time. force, thereby increasing the stability of the grasped object. In the underactuated finger 1, a small hole with a diameter of 1 mm is left on the inner plate 1102 of the distal phalanx, through which the steel wire rope is inserted, and successively passes through the inner plate 1102 of the distal phalanx, the inner plate 1202 of the middle phalanx, and the inner plate 1202 of the proximal phalanx. The inner plate 1302 is guided by the miniature guide wheel 2102 in the upper side panel of the base and then passes through the rectangular hole 2104 of the flexible cable traction. The opening of the cable pulling rectangular hole 2104 is large, which can prevent the wire rope from being greatly worn when it shrinks. The wire rope passes through the rectangular hole 2104 of the cable traction and then vertically enters the small hole on the traction cable reel 3001, ties the rope at the lower end to limit the position, and then pulls above the underactuated finger 1 to straighten the wire rope. Tethered knots at the knots. When the stepping motor 3004 is activated, the traction cable reel 3001 is rotated to guide the wire rope to shrink along the spiral groove, and the underdriven fingers are pulled to realize the function of bending and grasping; when the manipulator releases the object, the stepping motor 3004 reverses, The wire rope is loosened along the original path, and the elastic body joint provides the restoring force to restore the underactuated finger to the hovering state.

As shown in Figure 12, if the diameter of the grasping object is small and it is not suitable for touching part of the knuckles, the second knuckle can be removed and changed to a two-knuckle manipulator, which can also grasp objects.

To sum up, the present invention adopts the design concept of modular under-actuating. First, a corresponding installation mechanism is designed on the modular fingers for the rapid disassembly and assembly of the manipulator; second, the corresponding finger joints can be freely selected according to the actual use requirements. The number of knuckles can be freely selected, and the connection methods such as screws, studs, double-ended studs, dovetail grooves and T-slots can be used to avoid the tedious process of disassembling and assembling the manipulator, and only need to replace the corresponding fingers. In addition, the present invention also improves the degree of flexibility of the underactuated fingers, and the friction-increasing anti-skid layer adopts a flexible rubber material, which is more reliable for grasping some fragile items and has a wide range of applications.

Claims (9)

1. A flexible cable traction underactuated four-finger manipulator with elastic joints, characterized in that: it comprises an underactuated finger part, a mounting base part and a power drive part, and the underactuated finger part is connected with the power drive part through the mounting base part ; The underactuated finger part includes four underactuated fingers with the same structure, and the underactuated fingers include end knuckles, middle knuckles, proximal knuckles, and two elastic body joints, and the two elastic body joints have two ends. They are embedded between the end knuckles, the middle knuckles and between the middle knuckles and the proximal knuckles respectively; the end knuckles include the end knuckle inner plate, the end knuckle outer plate and the end knuckle friction rubber pad , the inner plate of the end phalanx and the outer plate of the end phalanx are wedged together through the dovetail groove, and the friction-increasing rubber pad of the end phalanx is embedded in the T-shaped groove opened on the inner side of the inner plate of the end phalanx; the middle phalanx includes the middle phalanx The inner plate, the outer plate of the middle phalanx and the rubber pad for increasing the friction of the middle phalanx, the inner plate of the middle phalanx and the outer plate of the middle phalanx are wedged by the dovetail groove, and the rubber pad of increasing the friction of the middle phalanx is embedded in the inner side of the inner plate of the middle phalanx. In the T-shaped groove of Through dovetail groove wedging, the proximal phalanx friction-increasing rubber pad is embedded in the T-shaped groove opened on the inner side of the proximal phalanx inner plate; The power drive part is used for power supply in the whole grasping process of the manipulator, including a stepping motor, a coupling, a traction cable winding wheel and a motor synchronously driving the rotating shaft; The installation base part includes an upper panel of the base, a left panel of the base, and a right panel of the base. The upper panel of the base is installed on the left panel of the base and the right panel of the base. The upper panel of the base is provided with four Underactuated finger connection seat, four underactuated finger connection seat are used to connect four identical underactuated fingers, four underactuated finger connection seat are symmetrically arranged in two pairs, underactuated finger connection seat includes double-ended stud, miniature guide wheel, A pair of L-shaped fixed lugs and a rectangular hole for flexible cable traction, the pair of L-shaped fixed lugs are fixed back-to-back on the upper side panel of the base with bolts, and the stud bolts are fixed on a pair of L-shaped fixed lugs through nuts , the miniature guide wheel is sleeved on the stud bolt and is located between the two L-shaped fixed lugs, and the upper side panel of the base located between the two L-shaped lugs is provided with a rectangular hole for pulling a flexible cable; the proximal knuckle rotates Installed on the stud; two miniature bearings are symmetrically installed on the right panel of the base and the left panel of the base, and two pairs of miniature bearings are fixed between two motors to drive the shaft synchronously, and two traction flex cable reels The fixed sleeve is mounted on the two motor synchronous driving shafts, the two stepping motors are respectively connected with the corresponding motor synchronous driving shafts through the coupling, and the two stepping motors are installed on the right panel of the base through the motor mounting bracket; The inner and outer plates of the end, middle and proximal phalanx of the underactuated fingers are all provided with small holes, one end of the flexible cable of each underactuated finger is fixed on the end phalanx, and the other end passes through the end, middle and proximal ends The small holes on the inner and outer plates of the knuckles and the rectangular holes for cable traction are fixed on the corresponding traction cable reels. 2 . The underactuated four-fingered manipulator with flexible cable traction with elastic joints according to claim 1 , wherein the diameter of the double-ended stud is 5 mm, and the proximal knuckles of the underactuated fingers pass through the proximal phalanx of the underactuated finger. 3 . The circular through holes formed by the semicircular through holes symmetrically opened on the inner plate of the end phalanx and the outer plate of the proximal phalanx respectively are rotatably installed on the stud bolts, and the traction cable reel is located in the middle of the proximal phalanx. 3. A flexible cable traction under-actuated four-finger manipulator with elastic joints according to claim 1, characterized in that: the traction flexible cable reel is in the form of thin middle and thick ends, and the central cylindrical hole is used for placing The motor drives the shaft synchronously, and there are positioning threaded holes on the thick cylinder head at both ends to fix the motor synchronously drive shaft, so that the traction cable reel and the motor synchronously drive the shaft to rotate at the same time without offset. Both ends of the thin cylinder are provided with spiral grooves, which can restrict the flexible cable in the grooves to prevent falling off and dislocation. 4 . The four-fingered manipulator with flexible cable traction and underdrive according to claim 1 , wherein the inner diameter of the miniature bearing is 6mm and the outer diameter is 15mm, and each miniature bearing is respectively embedded in the left panel of the base. 5 . , In the right panel of the base, the inner ring of the miniature bearing is matched with the synchronous drive shaft of the motor. 5. The four-fingered manipulator with flexible cable traction under-actuated with elastic joints according to claim 1, characterized in that: there are threaded holes above the left panel of the base and the right panel of the base for connecting the upper side of the base The lower part of the panel is provided with an anchor screw countersunk head seat, which is used to fix the manipulator on the base. 6 . The under-actuated four-fingered manipulator with flexible cable traction with elastic joints according to claim 1 , wherein the flexible cable is a steel wire rope with a diameter of 0.45 mm. 7 . 7 . The underactuated four-finger manipulator with flexible cable traction with elastic joints according to claim 1 , wherein the end, middle and proximal knuckles of the underactuated fingers are made of PLA material, which can be 3D printed. 8 . way of processing. 8 . The underactuated four-fingered manipulator with flexible cable traction with elastic joints according to claim 1 , wherein the elastic joints are made of elastic rubber material. 9 . 9 . The underactuated four-fingered manipulator with flexible cable traction with elastic joints according to claim 1 , wherein the underactuated fingers can also be composed of two-knuckle underactuated fingers by terminal knuckles and proximal knuckles. 10 . .