CN113829328A

CN113829328A - Flexible mechanical arm with positive angle compensation

Info

Publication number: CN113829328A
Application number: CN202111026811.5A
Authority: CN
Inventors: 杨灿军; 武鑫; 李佳; 赵起超
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2021-09-02
Filing date: 2021-09-02
Publication date: 2021-12-24
Anticipated expiration: 2041-09-02
Also published as: CN113829328B

Abstract

The invention discloses a flexible mechanical arm with positive angle compensation. The flexible mechanical arm is linearly stacked through the segmented flexible units, the length of the whole flexible mechanical arm can be controlled by selecting the number of stacked segments according to actual needs when the flexible mechanical arm is used, and the length adjustment design is very simple; through designing into every section flexible unit to become by a plurality of flexible modules that form the annular range and form, all articulated between each flexible module and between the four isosceles trapezoid piece of constituteing every flexible module to can design many haulage ropes as required, when using haulage rope control flexible arm to shorten, can realize the flexible length difference in different positions of flexible arm through the work between the different haulage ropes of control, thereby make flexible arm can be crooked to different directions, and do not confine to the flexible of linear direction.

Description

Flexible mechanical arm with positive angle compensation

Technical Field

The invention relates to the technical field of flexible mechanical arm design, in particular to a flexible mechanical arm with positive angle compensation.

Background

The paper folding robot is a robot prepared by paper folding technology research, the inspiration of the paper folding robot is derived from the paper folding technology of Japan, firstly, scientists change the shape of paper by researching the way of paper folding, and simultaneously utilize the flexibility and toughness of the paper to complete target action and assigned tasks, and then more and more scientists are invested in the field of paper folding robots, but the paper folding mechanism has small rigidity and is difficult to bear larger force and moment. Therefore, the paper folding robot is difficult to be practically used. Meanwhile, the kinematic model and the dynamic model of the paper folding robot are extremely complex, and the precision of the paper folding robot is limited, so that the precision control of the robot is difficult to ensure.

For example, the invention application with publication number CN110394795A discloses a high-storage-rate self-folding pneumatic soft mechanical arm based on the paper folding theory, which comprises a soft driver, upper and lower end cover plates and an inflation system, wherein the soft driver is a similar cylindrical shell, two ends of the soft driver are sealed and fixed with the upper and lower end cover plates, an inner cavity of the soft driver is inflatable, the shell is of a multi-layer soft laminated structure, and an airtight layer, an elastic layer, a limiting layer and a thermal protection layer are sequentially arranged from inside to outside. The soft driver shell is designed into a topological form based on a paper folding theory, can realize axial large-stroke telescopic driving, is driven to expand in an inflation mode of an inflation system to an inner cavity, and is self-folded in a mode of releasing elastic potential energy of an elastic layer after the inner cavity is exhausted. The device may also include a restraining cable to effect the bending drive.

For another example, the invention application with publication number CN112223259A discloses a bionic pneumatic soft worm robot with high storage rate based on paper folding theory, which comprises a flexible driver, front and rear end cover plates, pneumatic feet and an inflation system. Two ends of the flexible driver are respectively bonded with the front end cover plate and the rear end cover plate, and the flexible driver is expanded in a manner of inflating through an inflation system to drive the front exhaust movable foot to move forwards; the flexible driver is used for driving the exhaust movable foot to move forwards, so that the axial large-stroke bionic crawling is realized. The pneumatic foot is stretched and contracted through the air bag, and the included angle between the hinge connecting piece and the ground is adjusted, so that the friction form between the pneumatic foot and the ground is changed to realize unidirectional movement.

In the prior art, the paper folding structures are pneumatically controlled, only simple extension and shortening can be performed, and the moving direction cannot be actively controlled; and the design length of the paper folding structure is fixed and cannot be adjusted according to the requirement.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the flexible mechanical arm with the forward angle compensation based on the paper folding theory.

A flexible mechanical arm with positive angle compensation comprises a plurality of sections of flexible units which are linearly stacked and a driving mechanism for driving each flexible unit to stretch and retract;

each flexible unit comprises a plurality of telescopic modules which are arranged in an annular mode, each telescopic module comprises four isosceles trapezoid sheets, the side faces of the four isosceles trapezoid sheets are sequentially hinged to form a telescopic module of a quadrangular frustum structure, when the plurality of telescopic modules of each flexible unit are arranged in an annular mode, the top face of the quadrangular frustum structure faces the center of the inner side of the annular mode, and the bottom face of the quadrangular frustum structure deviates from the center of the inner side of the annular mode;

the isosceles trapezoid sheets used by the telescopic modules in each section of flexible unit are all the same in size and shape, and the adjacent telescopic modules in each section of flexible unit are hinged through the upper bottom sides of the two isosceles trapezoid sheets which are attached to each other; the height of isosceles trapezoid piece is shown as h, and the upper base is an, and the lower base is b, and every section of flexible unit includes n flexible module, then satisfies:

the drive mechanism includes: the drawing rope sequentially penetrates through at least part of the isosceles trapezoid sheets in each section of flexible unit, the drawing rope used for drawing at least one side of the flexible unit to be folded and shortened, and the retracting unit located on the outer side of the section of flexible unit at the tail end and used for retracting the drawing rope.

The flexible mechanical arm is in a minimum compression state, the angle projected to the horizontal plane by the telescopic module is minimum, when the flexible mechanical arm is in a maximum stretching state, the angle projected to the horizontal plane by the telescopic module is maximum, and the angle compensation is gradually increased in the process of transferring from the maximum stretching state to the minimum compression state, so that the angle compensation is provided. In order to meet the requirements of maximum stretching and minimum compensation, when the flexible mechanical arm is in a maximum stretching state, the angle compensation is set to be 0, at the moment, all the telescopic modules are tightly attached, and the size relation of the isosceles trapezoid pieces is determined according to the state at the moment. Under the condition that the shape of the isosceles trapezoid sheet meets the formula, the flexible unit can be stretched to the maximum length, and if the shape deviates from the relationship of the formula, the flexible unit cannot be stretched to the maximum length when being folded and stretched.

Preferably, each section of flexible unit comprises at least 3 telescopic modules. More preferably, each section of flexible unit comprises 3, 4, 6 or 8 telescopic modules.

Preferably, the outside that is located a lesson flexible unit of tail end is equipped with a mounting panel, and one side that the mounting panel deviates from flexible unit is equipped with receive and release the unit, every haulage rope correspondence is equipped with a set of unit that receive and releases, receive and release the unit and include the take-up reel to and drive take-up reel pivoted motor, be equipped with the hole of dodging that supplies the haulage rope to pass on the mounting panel.

Preferably, all the telescopic modules of all the flexible units are grouped, and all the telescopic modules arranged on the same straight line between adjacent flexible units are grouped into one group and controlled by one traction rope.

Preferably, each section of flexible unit comprises an even number of telescopic modules,

grouping all the telescopic modules of all the flexible units, dividing every two telescopic modules of the same flexible unit into a small group,

the small groups arranged on the same straight line between the adjacent flexible units are divided into a large group and controlled by a traction rope.

The flexible mechanical arm is pulled by the pulling rope to fold the isosceles trapezoid pieces in the telescopic module, the pulling rope is required to be released after the folding to keep the flexible unit in a stretched state so as to recover the shape of the flexible mechanical arm, and the flexible mechanical arm can be vertically used and recovered by means of gravity under the condition that a corresponding recovery driving structure is not arranged.

Preferably, the two isosceles trapezoid pieces are hinged in a hinge structure. More preferably, a torsion spring for keeping the flexible unit in a stretched state is further provided in the hinge structure. Hinge structure is including the articulated hole post that is located isosceles trapezoid piece side and the axle core that passes articulated hole post, can set up automatic recovery's torsional spring on the axle core and realize making the purpose that flexible unit keeps tensile state, like this, at the tensile in-process of haulage rope, as long as overcome the torsion of torsional spring and just can make the folding compression of flexible unit, and with the haulage rope release back, the torsional spring can provide the power that resumes again and make flexible arm extension straighten. When the hinge structure is used, the isosceles trapezoid sheet and the corresponding hinge hole column can be integrally formed and manufactured in a 3D printing mode.

The flexible mechanical arm is linearly stacked through the segmented flexible units, the length of the whole flexible mechanical arm can be controlled by selecting the number of stacked segments according to actual needs when the flexible mechanical arm is used, and the length adjustment design is very simple; through designing into every section flexible unit to become by a plurality of flexible modules that form the annular range and form, all articulated between each flexible module and between the four isosceles trapezoid piece of constituteing every flexible module to can design many haulage ropes as required, when using haulage rope control flexible arm to shorten, can realize the flexible length difference in different positions of flexible arm through the work between the different haulage ropes of control, thereby make flexible arm can be crooked to different directions, and do not confine to the flexible of linear direction.

Drawings

Fig. 1 is a schematic side view of a flexible robot arm according to the present invention.

Fig. 2 is a schematic perspective view of the flexible manipulator of the present invention without a pulling rope.

Fig. 3 is a schematic top view of the flexible robot arm of the present invention.

Fig. 4 is a perspective view of another perspective view of the flexible manipulator of the present invention without a pull rope.

Fig. 5 is a schematic perspective view of a linear stacking of flexible units.

Fig. 6 is a schematic perspective view of a single flexible unit.

Fig. 7 is a schematic perspective view of a telescopic module.

Fig. 8 is a perspective view of the telescopic module in a folded state.

Fig. 9 is a schematic structural diagram of a first use state of the flexible manipulator of the present invention.

Fig. 10 is a structural schematic diagram of a second use state of the flexible mechanical arm of the invention.

Fig. 11 is a geometric relationship diagram.

Detailed Description

As shown in fig. 1 to 5, a flexible mechanical arm with positive angle compensation based on a paper folding theory includes a plurality of sections of linearly stacked flexible units 1 and a driving mechanism for driving each flexible unit 1 to stretch. The structure shown in the figure is a flexible unit 1 with 5 sections. When the flexible manipulator is used, the length of the whole flexible manipulator can be controlled by selecting the number of stacked sections according to actual needs, and the length adjustment design is very simple.

As shown in fig. 6-8, each section of flexible unit 1 comprises a plurality of flexible modules 2 arranged in a ring shape, each flexible module 2 comprises four isosceles trapezoid plates 3, the side surfaces of the four isosceles trapezoid plates 3 are sequentially hinged to form the flexible modules 2 of the quadrangular frustum structure, when the plurality of flexible modules 2 of each section of flexible unit 1 are arranged in a ring shape, the top surface of the quadrangular frustum structure faces towards the inner side center of the ring shape, and the bottom surface of the quadrangular frustum structure deviates from the inner side center of the ring shape. Namely, the two waist positions of the isosceles trapezoid pieces 3 are hinged with the waist positions of the two adjacent isosceles trapezoid pieces 3, and the four isosceles trapezoid pieces 3 surround a circle. The upper bottom and the lower bottom of the quadrangular frustum structure are hollow, so that after the quadrangular frustum structure is stressed and extruded in the side direction, the quadrangular frustum structure deforms, the cross section of the quadrangular frustum structure is changed into a rhombus from a square, and the size of the quadrangular frustum structure in the stress direction is compressed and shortened.

The number of the telescopic modules 2 in each section of the flexible unit 1 can be selected according to actual needs, the smaller the number is, the coarser the control precision of the whole flexible mechanical arm is, the larger the number is, and the finer the control precision of the whole flexible mechanical arm is. Typically at least 3 telescopic modules 2 are included, for example each section of flexible unit 1 may comprise 3, 4, 6 or 8 telescopic modules 2.

The adjacent telescopic modules 2 in each section of flexible unit 1 are hinged through the upper bottom sides of two isosceles trapezoid sheets 3 which are attached to each other. Generally, the isosceles trapezoid-shaped pieces 3 used by the telescopic modules 2 in each section of the flexible unit 1 are all the same in size and shape, so that the production is convenient, and the control is easy. The height of isosceles trapezoid piece 3 is shown as h, and the upper base is an, and the lower base is b, and every section of flexible unit 1 includes n flexible modules, then satisfies:

if the shape of the isosceles trapezoid piece 3 satisfies the above formula, the flexible unit 1 can be stretched to the maximum thickness, and if the shape deviates from the relationship of the formula, the flexible unit 1 cannot be stretched to the maximum thickness when stretched.

The drive mechanism includes: sequentially penetrates through at least part of the isosceles trapezoid sheets 3 in each section of the flexible unit 1, a traction rope 6 for driving at least one side of the flexible unit 1 to be folded and shortened, and a retracting and releasing unit which is positioned at the outer side of the section of the flexible unit 1 at the tail end and used for retracting and releasing the traction rope 6. The isosceles trapezoid sheet 3 is correspondingly provided with a traction hole 11 for the traction rope 6 to pass through. The outer side of the flexible unit 1 at the tail end is provided with a mounting plate 7, one side, deviating from the flexible unit 1, of the mounting plate 7 is provided with a winding and unwinding unit, each traction rope 6 is correspondingly provided with a group of winding and unwinding units, each winding and unwinding unit comprises a winding disc 8 and a motor 9 for driving the winding disc 8 to rotate, and the mounting plate 7 is provided with a avoiding hole 10 for the traction rope 6 to pass through.

In one embodiment, all the telescopic modules 2 of all the flexible units 1 are grouped, and the telescopic modules 2 arranged on the same line between adjacent flexible units 1 are grouped and controlled by a traction rope 6.

In another embodiment, each flexible unit 1 comprises an even number of telescopic modules 2, all the telescopic modules 2 of all the flexible units 1 are grouped, each telescopic module 2 of the same flexible unit 1 is divided into two groups, and each group arranged on the same straight line between adjacent flexible units 1 is divided into one large group and controlled by one hauling rope 6. The structure shown in the figure is that in this embodiment, each flexible unit 1 in the figure comprises 8 telescopic modules 2 which are divided into 4 large groups and controlled by using 4 traction ropes 6. And, every haulage rope 6 passes adjacent two in four isosceles trapezoid piece 3 of every flexible module 2 in proper order, after haulage rope 6 passed that the isosceles trapezoid piece 3 that leans on each other in two flexible modules 2 that are located same section flexible unit 1, one end passed that the isosceles trapezoid piece 3 that is close to receive and release unit one side in one of them flexible module 2, the other end passed that the isosceles trapezoid piece 3 of keeping away from receive and release unit one side in another flexible module 2, then the haulage rope passed that the isosceles trapezoid piece 3 that leans on each other in two flexible modules 2 that are located adjacent two sections flexible unit 1 again, haulage rope 6 wholly presents the broken line type.

The flexible mechanical arm is characterized in that the isosceles trapezoid pieces 3 in the telescopic module 2 are folded by the traction of the traction rope 6, the traction rope 6 is required to be released after the folding to keep the flexible unit 1 in a stretched state so as to recover the shape of the flexible mechanical arm, and the flexible mechanical arm can be vertically used and recovered by means of gravity under the condition that a corresponding recovery driving structure is not arranged.

In a preferred embodiment, as shown in the figures, two isosceles trapezoid plates 3 are hinged with each other in a hinge structure, and the hinge structure comprises hinge holes 4 at the side surfaces of the isosceles trapezoid plates 3 and a shaft core 5 penetrating through the hinge holes 4. In an embodiment, a torsion spring (in the embodiment shown in the figure, no torsion spring is used) for keeping the flexible unit 1 in a stretched state is further arranged in the hinge structure, and an automatically-restoring torsion spring can be arranged on the shaft core 5 to achieve the purpose of keeping the flexible unit 1 in the stretched state, so that in the stretching process of the traction rope 6, the flexible unit 1 can be folded and compressed as long as the torsion force of the torsion spring is overcome, and after the traction rope 6 is released, the torsion spring can provide restoring power to enable the flexible mechanical arm to extend and straighten. When the hinge structure is used, the isosceles trapezoid sheet 3 and the corresponding hinge hole column 4 can be integrally formed and manufactured in a 3D printing mode.

When in use, a mounting plate can be arranged on the outer side of the flexible unit 1 at the head end (the lower end in fig. 1), and the mounting plate is used for mounting some operating mechanisms on the flexible mechanical arm, so that the flexible mechanical arm can realize corresponding functions, such as some structures for grabbing articles and the like.

The following calculation of the formula required to be satisfied for stretching to the maximum thickness proves that the vertical arrangement of the flexible units 1 shown in the figure is taken as an example.

As shown in fig. 11, the projection of the telescopic module 2 in the vertical direction, wherein I, II represents two horizontal and vertical isosceles trapezoid shaped pieces; h is the height of the isosceles trapezoid piece 3, a is the upper base of the isosceles trapezoid piece 3, and b is the lower base of the isosceles trapezoid piece 3. d is the projection of the height of the isosceles trapezoid piece on a vertical plane. h' is the projection of the height of the isosceles trapezoid piece on the horizontal plane.

Is the included angle between the isosceles trapezoid piece and the horizontal plane. θ is the projection angle of the telescopic module 2 in the horizontal direction. Psi denotes the angle of rotation of the isosceles trapezoid shaped pieces in the vertical direction about the central axis. Can be expressed as the following expression:

according to fig. 11(b), the projection angle of the telescopic module 2 in the horizontal direction can be expressed as:

as shown in fig. 11(d), the height of the isosceles trapezoid in the vertical direction is mainly determined by the rotation angle ψ:

by integrating the above formula, we can obtain a specific expression of the projection angle θ of the telescopic module 2 in the vertical direction as follows:

as shown in the above formula, θ changes continuously with the change of the rotation angle, and the key of the telescoping mechanism 2 in the process of continuous telescoping change is to ensure that a section of the flexible unit 1 composed of n telescoping modules 2 can form a circle on the circumference at any twisting stage, that is, the total angle of the space relative to the main axis of the flexible manipulator is always equal to 360 °. In order to compensate the angle loss in different torsion stages, an angle compensation mechanism needs to be designed to compensate the angle.

For the angle compensation mechanism, because the adjacent telescopic modules 2 in each section of flexible unit 1 are hinged through the upper bottom sides of the two isosceles trapezoid sheets 3 which are attached to each other, and the upper bottom sides are positioned inside the whole flexible mechanical arm, the angle compensation mechanism is an outward-open compensation mechanism, namely, the provided angle compensation is forward compensation.

The angle change is shown by the following formula, wherein theta_adaptiveTo compensate for the angle:

nθ+θ_adaptive＝360°

when the telescopic unit is stretched completely (psi ═ 0 °), θ reaches the maximum value, and because of adopting the angle compensation that opens outward, can only carry out forward compensation to the angle, at this moment, the compensation angle size that is located inboard, the upper base one end of isosceles trapezoid piece of flexible arm can provide is 0. The size of the isosceles trapezoid shaped piece should be determined according to the geometrical relationship at this time.

The following can be obtained:

as shown in fig. 9 and 10, each section of flexible unit 1 of the flexible mechanical arm is designed to be composed of a plurality of annularly arranged telescopic modules 2, and the telescopic modules 2 and the four isosceles trapezoid-shaped pieces 3 forming each telescopic module 2 are hinged to each other, so that a plurality of traction ropes 6 can be designed as required, when the traction ropes 6 are used for controlling the flexible mechanical arm to shorten, the telescopic lengths of different parts of the flexible mechanical arm can be different by controlling the work among different traction ropes 6, and the flexible mechanical arm can be bent to different directions without being limited to the linear telescopic extension.

Claims

1. The flexible mechanical arm with the positive angle compensation is characterized by comprising a plurality of sections of flexible units which are linearly stacked and a driving mechanism for driving the flexible units to stretch and retract;

2. The flexible robotic arm of claim 1, wherein each section of flexible units comprises at least 3 telescoping modules.

3. The flexible robotic arm of claim 2, wherein each section of flexible unit comprises 3, 4, 6 or 8 telescoping modules.

4. The flexible mechanical arm according to claim 1, wherein a mounting plate is arranged on the outer side of the tail-most flexible unit, the winding and unwinding units are arranged on the side, away from the flexible unit, of the mounting plate, a group of winding and unwinding units are correspondingly arranged on each traction rope, each winding and unwinding unit comprises a winding disc and a motor for driving the winding disc to rotate, and a avoiding hole for the traction rope to pass through is formed in the mounting plate.

5. The flexible robotic arm of claim 1, wherein all the telescopic modules of all the flexible units are grouped, and the telescopic modules arranged in the same line between adjacent flexible units are grouped and controlled by a pulling rope.

6. The flexible robotic arm of claim 1, wherein each section of flexible units comprises an even number of telescoping modules,

7. The flexible mechanical arm as claimed in claim 1, wherein the two isosceles trapezoid pieces are hinged with each other in a hinge structure.

8. The flexible robot arm of claim 7, further comprising a torsion spring disposed within the hinge structure for maintaining the flexible unit in tension.