CN116476034B

CN116476034B - Four-degree-of-freedom miniature parallel robot and manufacturing and control method thereof

Info

Publication number: CN116476034B
Application number: CN202310510732.4A
Authority: CN
Inventors: 刘一得; 冯博; 曲绍兴
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2023-05-08
Filing date: 2023-05-08
Publication date: 2023-11-28
Anticipated expiration: 2043-05-08
Also published as: CN116476034A

Abstract

The invention discloses a four-degree-of-freedom miniature parallel robot and a manufacturing and control method thereof, and belongs to the field of miniature parallel robots. The invention realizes the manufacture of the four-degree-of-freedom micro parallel robot by means of plane dimension design, layering design, intelligent composite material production and splicing assembly, and provides a corresponding high-precision control method. The miniature parallel robot has the volume smaller than 40 cubic centimeters, the working space of 810 cubic millimeters, high-frequency working potential, repeated positioning accuracy of 20 micrometers, 4-degree-of-freedom motion capability and in-situ rotation.

Description

Four-degree-of-freedom miniature parallel robot and manufacturing and control method thereof

Technical Field

The invention belongs to the field of micro parallel robots, and particularly relates to a four-degree-of-freedom micro parallel robot and a manufacturing and control method thereof.

Background

Parallel ROBOTS, generally referred to as closed loop kinematic chain mechanisms, have a motion platform connected to a base by separate kinematic chains (Hamid D.Taghirad.PARALLEL ROBOTS MECHANICS AND CONTROL ISBN 987-7-111-58959-7). The miniature parallel robot generally refers to a parallel robot with a size below 5cm, and has higher precision and better dynamic response capability compared with a large parallel robot. However, due to the limitation of the dimension requirement, the design and the manufacture of the micro parallel robot cannot be realized in the traditional mode, and the micro parallel robot generally adopts a planar design and manufacture method at present. Planar material, meaning a material having a thickness that is much less (at least 1 order of magnitude) than its length and width, includes, but is not limited to: rigid planar materials such as metal plates, plastic plates, wood plates, carbon fiber plates, and soft planar materials such as high polymer films, gel layers, woven fabrics, metal foils, and the like. Planarization, the manner in which a planar material is processed, includes, but is not limited to: additive manufacturing modes such as 3D printing, spraying, extrusion, chemical synthesis and the like, or subtractive manufacturing modes such as cutting, linear cutting, laser ablation, photoetching, chemical etching and the like.

The intelligent composite material is a multilayer composite planar material manufactured by carrying out planarization processing and bonding on a planar material, and the composite planar material has the freedom of movement, so that different functions can be realized through three-dimensional. After planarization processing, the hard planar material in the intelligent composite material clamps the soft planar material, wherein the hard planar material can be utilized to rotate along a segmentation boundary after being segmented by planarization processing, so that the degree of freedom of movement is obtained. The specific structure of the intelligent composite material is shown in fig. 1, wherein materials 01 and 05 are hard plane materials, materials 02 and 04 are adhesive materials, material 03 is soft plane material, a division boundary obtained by carrying out planarization processing on the hard plane material is arranged in a dotted line square frame, and the dotted line is a rotating shaft of the hard plane material rotating along the division boundary by utilizing the soft plane material.

The design and manufacture of intelligent composite materials is a common way to construct miniature parallel robots. The parts and kinematic pairs can be constructed by utilizing the rigidity of the hard planar material and the degree of freedom of rotary motion brought by the soft planar material, so that the intelligent composite material meets the mechanical motion principle, and the intelligent composite material can be three-dimensionally arranged according to the requirement through planarization design, thereby constructing various micro-mechanisms and micro-robots.

A high-precision operation device generally employs a servo motor or piezoelectric ceramics as a drive. The traditional mechanical mechanism is generally driven by a servo motor, the precision is in the order of hundred micrometers, but the volume often exceeds thousand cubic centimeters, and high-frequency operation higher than 50Hz cannot be realized. The operating device for medical treatment and precision machining is generally driven by piezoelectric ceramics, the precision can reach the micron level, but the working space is generally smaller than hundred cubic millimeters, the price is high, and the load capacity is low.

Disclosure of Invention

The traditional parallel robot is limited by a design mode and a manufacturing process, and is difficult to compress the volume to the centimeter scale, so that the operation precision of the micrometer level is realized. There are thus many application difficulties in microscale operation. The existing micro-operation platform can realize the operation precision of the micron level, but has the defects of huge volume, high price, low operation freedom degree and the like relative to the operation range, and the micro-operation platform capable of realizing the translation and simultaneously combining the in-situ rotation operation functions is not available at present.

In order to solve the large-range operation requirement of high-degree-of-freedom high-precision operation, reduce the volume, weight and manufacturing cost of the miniature operation equipment, realize the translational and in-situ rotation combined four-degree-of-freedom operation, simultaneously have the micron-level operation precision, and the operation space reaches the hundred cubic millimeter level, the invention provides a four-degree-of-freedom miniature parallel robot.

The specific technical scheme adopted by the invention is as follows:

in a first aspect, the present invention provides a four-degree-of-freedom miniature parallel robot comprising a miniature parallel robot and a drive transmission mechanism;

the miniature parallel robot comprises four branched chains, and each branched chain is divided into a fixed platform part and a movable platform part;

the fixed platform part comprises a fixed platform connecting rod and a first connecting rod, and the fixed platform connecting rod is connected with the first connecting rod through a first common hinge; four fixed platform connecting rods in the four branched chains are spliced through the male and female heads to form a complete fixed platform;

the movable platform part comprises a second connecting rod, a third connecting rod, a fourth connecting rod, a fifth connecting rod, a sixth connecting rod, a seventh connecting rod, an eighth connecting rod and a ninth connecting rod; the second connecting rod is connected with the third connecting rod through a second common hinge; the four connecting rods are symmetrically distributed on two sides of the third connecting rod and are respectively connected with the third connecting rod through a third common hinge; the two fifth connecting rods are symmetrically arranged on the side where the two fourth connecting rods are located, and are respectively connected with the two fourth connecting rods through a fourth common hinge; the six connecting rods are symmetrically arranged on the sides where the two fifth connecting rods are arranged, and are respectively connected with the two fifth connecting rods through a fifth common hinge; the seventh connecting rod is positioned between the two sixth connecting rods and is connected with the two sixth connecting rods through a sixth common hinge respectively; the third connecting rod, the fourth connecting rod, the fifth connecting rod, the sixth connecting rod, the seventh connecting rod, the other sixth connecting rod, the other fifth connecting rod and the other fourth connecting rod are connected end to end, and in a non-working state, the fourth connecting rod, the fifth connecting rod and the sixth connecting rod are all vertical to the third connecting rod and the seventh connecting rod, inserting grooves are formed in the two fourth connecting rods and the two sixth connecting rods, and the two fourth connecting rods and the two sixth connecting rods are respectively connected and sealed by inserting a first inserting piece into the inserting grooves, so that a parallel four-bar structure is formed; the eighth connecting rod is connected with the seventh connecting rod through a seventh common hinge, a vacant area for placing the ninth connecting rod is arranged in the eighth connecting rod, and the ninth connecting rod is connected with the eighth connecting rod through the eighth common hinge; the ninth connecting rod is also provided with a splicing groove;

The four second connecting rods positioned at the bottoms of the four movable platform parts are respectively and correspondingly attached to the four first connecting rods around the fixed platform in a one-to-one correspondence manner, and the ninth connecting rods positioned at the tops of the four movable platform parts are gathered towards the center; the second plug-in pieces are jointly fixed through plug-in grooves of four ninth connecting rods and serve as a movable platform of the whole micro parallel robot;

the driving transmission mechanism comprises four sub-driving mechanisms which are arranged on the base, and the four sub-driving mechanisms are in one-to-one correspondence to drive four branched chains of the micro parallel robot; each sub-driving mechanism comprises a first driving connecting rod, a second driving connecting rod, a third driving connecting rod and a driving motor, wherein an output shaft of the driving motor is fixed with one end of the third driving connecting rod and forms transmission, the other end of the third driving connecting rod is hinged with one end of the second driving connecting rod, the other end of the second driving connecting rod is hinged with one end of the first driving connecting rod, the other end of the first driving connecting rod is fixedly connected with a first connecting rod in a driven branched chain, and the first driving connecting rod, the second driving connecting rod and the third driving connecting rod form parallel four-rod transmission, so that the rotation angle output by the driving motor is transmitted to the first connecting rod of the miniature parallel robot in equal proportion.

As a preferable aspect of the foregoing first aspect, all the connecting rods that constitute the micro parallel robot are processed by using a composite layered material, the middle layer of the composite layered material is a flexible planar material layer, two sides of the middle layer are hard planar material layers, the flexible planar material layer and the hard planar material layer are adhered and fixed by an adhesive material layer, two adjacent connecting rods keep the flexible planar material layer at a common hinge position and the hard planar material layer is broken, and edges of the hard planar material layers at two sides of the broken position are all provided with rectangular grooves at intervals and are mutually embedded by saw-tooth type edges formed by the rectangular grooves, so that the micro parallel robot can freely rotate around the common hinge under the coupling action of the flexible planar material layers.

As a preferable aspect of the first aspect, two insertion grooves are spaced apart on each ninth connecting rod, two second insertion pieces are inserted and fixed on the four ninth connecting rods in parallel, and two second insertion pieces are provided with mounting pieces for being matched with equipment to be driven.

As a preferable aspect of the first aspect, in each sub-driving mechanism of the driving transmission mechanism, the driving arm of the first driving link is parallel to the first link, the first driving link and the second driving link are hinged through a first bearing, the second driving link and the third driving link are hinged through a second bearing, and the distance from the output shaft of the driving motor to the second bearing is equal to the distance from the first bearing to the first common hinge corresponding to the current sub-driving mechanism, and the distance from the first bearing to the second bearing is equal to the distance from the output shaft of the driving motor to the first common hinge corresponding to the current sub-driving mechanism.

Preferably, in the first aspect, the driving motor is a micro servo motor.

Preferably, the flexible flat material layer is a soft polymer film, a soft gel layer, a soft woven fabric, or a soft metal foil; the hard flat material layer is a hard metal plate, a hard plastic plate, a hard glass plate, a hard resin plate, a hard wood plate and a hard composite material plate.

As a preferable aspect of the above first aspect, in the four branched fixed-platform part, two of the four fixed-platform links have male heads and two have female heads, and the four fixed-platform links are assembled into one body by the male heads and the female heads.

In a second aspect, the present invention provides a method for manufacturing a four-degree-of-freedom micro parallel robot according to any one of the first aspect, comprising the steps of:

s1, integrally arranging four fixed platform parts of four branched chains on a first drawing to serve as parallel processing objects, integrally arranging four movable platform parts of four branched chains on a second drawing to serve as parallel processing objects, and processing flexible plane material layers, hard plane material layers and bonding material layers corresponding to the four fixed platform parts and the four movable platform parts layer by layer according to the two drawings; in each processed material layer, the area of each connecting rod needs to be temporarily connected with the plate substrate;

S2, sequentially superposing and assembling material layers obtained by processing according to a first drawing to form a first plate which simultaneously comprises four fixed platform parts, sequentially superposing and assembling material layers obtained by processing according to a second drawing to form a second plate which simultaneously comprises four movable platform parts, removing all temporary connections on the first plate and the second plate, and separating the four fixed platform parts and the four movable platform parts from a plate substrate respectively by cutting;

s3, arranging first inserting pieces and second inserting pieces required by the four branched chains on a third drawing, processing the flexible flat material layer, the hard flat material layer and the bonding material layer by layer according to the third drawing, sequentially stacking the processed material layers, and separating all the first inserting pieces and the second inserting pieces from the plate substrate through cutting;

s3, assembling the four fixed platform parts and the four movable platform parts in a one-to-one correspondence manner to form four branched chains, splicing four fixed platform connecting rods at the bottoms of the four branched chains through male and female heads to form a complete fixed platform, simultaneously installing all first plug-in pieces on each pair of sixth connecting rods of the four branched chains in a plug-in manner, and installing second plug-in pieces on four ninth connecting rods at the tops of the four branched chains in a plug-in manner to serve as a movable platform of the whole micro parallel robot;

S4, respectively installing one sub-driving mechanism on the four first connecting rods of the miniature parallel robot, and fixedly installing the four sub-driving mechanisms into the base, so that interference between the four sub-driving mechanisms and the base in the working process is avoided, and the manufacturing of the miniature parallel robot with four degrees of freedom is completed.

As a preferable aspect of the second aspect described above, in S3, all the first plug pieces and the second plug pieces required on the four branches are arranged on the same drawing sheet as the parallel processing object.

In a second aspect, the present invention provides a control method for a four-degree-of-freedom micro parallel robot according to any one of the first aspect, including the steps of:

s1, determining a target space position vector t of a moving platform center point P in a fixed platform coordinate system { G } according to a control target, and calculating a rotation angle gamma of any ith branched chain _i I=1, 2,3,4, the formula is:

wherein: ^G R _P is a transformation matrix of a coordinate system from a fixed platform coordinate system { G } to a movable platform coordinate system { P }, and a line vector P _i ＝[rcosβ _i ,rsinβ _i ,-h]Angle beta _i Taking 60 degrees, 120 degrees, 240 degrees and 300 degrees for i=1, i=2, i=3 and i=4 respectively, wherein r is the distance from the center of the second plug sheet to the center line of the formed plug groove, and h is the length of the eighth connecting rod; normal vector s= [ -sin alpha _i ,cosα _i ,0]Angle alpha _i Taking 0 ° for i=1, i=2, i=3, i=4, respectively90°180°270°；The length of the fifth connecting rod;

s2, according to the cos gamma of each branched chain _i Calculating the angle theta of the output required by the driving motor in the sub-driving mechanism connected with the ith branched chain _i The calculation formula is:

wherein: a. the calculation formula of the three intermediate parameters b and c is as follows:

wherein: zeta type toy ₁ ＝[1,0,0] ^T ，ξ ₂ ＝[0,1,0] ^T ，ξ ₃ ＝[0,0,1] ^T The method comprises the steps of carrying out a first treatment on the surface of the Vector b _i ＝[Rcosα _i ,Rsinα _i ,0]R is the distance from the center of the fixed platform to the first common hinge; length ofL ₁ For the length of the first link L ₂ For the length of the second link, _s a thickness of the composite layered material;

s3, according to the angle theta of the required output of the driving motor in the sub-driving mechanism connected with each branched chain _i Issuing control instructions to the corresponding driving motors to drive the driving motors to output corresponding angles theta _i Make the center of the movable platformThe point P reaches the target position.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a four-degree-of-freedom miniature parallel robot based on an intelligent composite material and a planarization manufacturing process and a manufacturing and control method thereof, and the four-degree-of-freedom miniature parallel robot with small size, high precision, high frequency response, high operation bandwidth, large working space and high load can be manufactured. In the embodiment of the invention, the manufactured four-degree-of-freedom micro parallel robot can have repeated positioning accuracy of 20 mu m, high frequency response potential and 810mm at most ³ Working space, 12N/mm load stiffness. The robot has higher working condition adaptability, can replace the operation head according to different actual demands, realizes tasks such as cutting, puncturing and the like, and has stronger practicability.

Drawings

FIG. 1 is a schematic diagram of a specific structure of an intelligent composite material;

FIG. 2 is a plan view of a branched chain in an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating the rectangular groove opening in an embodiment of the present invention;

FIG. 4 is a schematic diagram of an arrangement of islands-chains in an embodiment of the present invention;

FIG. 5 is an overall design of 4 branches according to an embodiment of the present invention;

FIG. 6 is a drawing of a four-degree-of-freedom micro parallel robot in an embodiment of the invention;

FIG. 7 is a flow chart of the actual production of the four-degree-of-freedom micro parallel robot in the embodiment of the invention;

FIG. 8 is a schematic diagram illustrating an assembly process of a movable platform part and a fixed platform part according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of two types of plug connectors according to an embodiment of the present invention;

FIG. 10 is a flowchart of the plugging assembly of a micro parallel robot in an embodiment of the present invention;

FIG. 11 is an assembly schematic diagram of a micro parallel robot and a driving transmission mechanism thereof according to an embodiment of the present invention;

FIG. 12 is a diagram showing a comparison of a geometric model of a four-degree-of-freedom micro-robot with a conventional X4 in accordance with an embodiment of the present invention;

FIG. 13 is a schematic view of controlling the pose of a micro-robot movable platform by changing the rotation angle of a motor according to the embodiment of the invention;

FIG. 14 is a graph showing the comparison of actual moving platform trajectory data with theoretical trajectory data in an embodiment of the present invention;

fig. 15 shows an implementation example under three different tasks in the embodiment of the present invention.

Detailed Description

In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the invention, whereby the invention is not limited to the specific embodiments disclosed below. The technical features of the embodiments of the invention can be combined correspondingly on the premise of no mutual conflict.

In the description of the present invention, it should be understood that the terms "first" and "second" are used solely for the purpose of distinguishing between the descriptions and not necessarily for the purpose of indicating or implying a relative importance or implicitly indicating the number of features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature.

In order to solve the large-range operation requirement of high-degree-of-freedom high-precision operation, reduce the volume, weight and manufacturing cost of the miniature operation equipment, realize the translational and in-situ rotation combined four-degree-of-freedom operation, simultaneously have the micron-level operation precision, and the operation space reaches the hundred cubic millimeter level, the invention provides a four-degree-of-freedom miniature parallel robot. It should be noted that the concept of the degree of freedom of the present invention refers to the motion that the robot can perform in space, and in the three-dimensional space described by the cartesian coordinate system (ozz), the rigid body has at most six degrees of freedom, which are translation along three axes X, Y and Z and rotation about three axes X, Y and Z, respectively.

The four-degree-of-freedom Micro parallel robot (hereinafter also referred to as Micro-X4) of the present invention is described in detail below.

In one embodiment of the invention, a four-degree-of-freedom micro parallel robot is provided, the basic composition of which can be divided into two parts of the micro parallel robot and a driving transmission mechanism. Specific structural implementation forms of the micro parallel robot and the driving transmission mechanism are described in detail below.

The miniature parallel robot comprises four branched chains, and each branched chain is divided into a fixed platform part and a movable platform part. The fixed platform part is used for assembling to form a complete fixed platform and is also provided with a part of connecting rod connected with the movable platform part, the movable platform part is assembled on the fixed platform, and the top is used for installing the movable platform. The specific structural forms of the fixed platform part and the movable platform part are described in detail below.

As shown in the left view of fig. 2, the above-mentioned fixed platform part of the present invention includes a fixed platform link 0 and a first link 1, and the fixed platform link 0 and the first link 1 are connected by a first common hinge. Four fixed platform connecting rods 0 in the four branched chains are spliced through the male and female heads to form a complete fixed platform. Because the four branched fixed platform parts are not completely consistent because the fixed platform parts are spliced according to the male and female heads, specifically, two of the four fixed platform connecting rods 0 are provided with the male heads and two of the four fixed platform connecting rods are provided with the female heads, and therefore, the four fixed platform connecting rods 0 can be assembled into a whole through the male heads and the female heads. It should be noted that, the left diagram of fig. 2 only shows the fixed platform portion in the form of a male head, and the fixed platform portion in the form of a female head may be correspondingly disposed according to the assembly relationship. Finally, as can be seen from the left-hand view of fig. 2, the entire stationary platen portion is mirror-symmetrical left-right.

As shown in the right view of fig. 2, the above-mentioned movable platform part of the present invention includes a second link 2, a third link 3, a fourth link 4, a fifth link 5, a sixth link 6, a seventh link 7, an eighth link 8, and a ninth link 9. The remaining second, third, fourth, fifth, sixth, seventh and ninth links 2, 3, 4, 5, 6, 7 and 9 are each rectangular plate-shaped except for the eighth link 8, and the eighth link 8 is L-shaped, specifically, is formed by opening a sub-rectangular region accommodating the ninth link 9 in the rectangle. For convenience of description, four directions up, down, left, and right are defined in the posture shown in fig. 2, whereby the connection relationship between all links of each movable platform part is as follows: the lower edge of the second connecting rod 2 is connected with the upper edge of the third connecting rod 3 through a second common hinge; the four connecting rods 4 are symmetrically distributed on the left side and the right side of the third connecting rod 3 and are respectively connected with the left side and the right side of the third connecting rod 3 through third common hinges, so the third common hinges are symmetrically provided with two; the two fifth connecting rods 5 are symmetrically arranged on the sides of the two fourth connecting rods 4, and the upper edges of the two fifth connecting rods 5 are respectively connected with the lower edges of the two fourth connecting rods 4 through fourth common hinges, so the fourth common hinges are symmetrically provided with two; the two sixth connecting rods 6 are symmetrically arranged on the sides of the two fifth connecting rods 5, and the lower edges of the sixth connecting rods 6 are respectively connected with the upper edges of the two fifth connecting rods 5 through fifth common hinges, so that the five common hinges are symmetrically two; the seventh connecting rod 7 is located between the two sixth connecting rods 6, and the left and right sides of the seventh connecting rod 7 are respectively connected with the two sixth connecting rods 6 through sixth common hinges, so that the sixth common hinges have two symmetrical hinges. The third connecting rod 3, the fourth connecting rod 4, the fifth connecting rod 5, the sixth connecting rod 6, the seventh connecting rod 7, the other sixth connecting rod 6, the other fifth connecting rod 5 and the other fourth connecting rod 4 are connected end to end, a rectangular gap is formed by enclosing the inside, and the fourth connecting rod 4, the fifth connecting rod 5 and the sixth connecting rod 6 are vertical to the third connecting rod 3 and the seventh connecting rod 7 in the assembled non-working state; the two fourth connecting rods 4 and the two sixth connecting rods 6 are respectively provided with an inserting groove, and the two fourth connecting rods 4 and the two sixth connecting rods 6 are respectively connected and sealed by inserting the first inserting sheets 32 into the inserting grooves, so that a parallel four-rod structure is formed. The upper edge of the eighth connecting rod 8 is connected with the lower edge of the seventh connecting rod 7 through a seventh common hinge, a vacant area for placing the ninth connecting rod 9 is arranged in the eighth connecting rod 8, and the right edge of the ninth connecting rod 9 is connected with the left edge of the eighth connecting rod 8 through the eighth common hinge; the ninth connecting rod 9 is also provided with a plugging slot, and the plugging slot is used for connecting the movable platform. Finally, it can be seen from the right-hand view of fig. 2 that the entire movable platform section is mirror-symmetrical left and right, except for the eighth link 8 and the ninth link 9.

As shown in fig. 10, four second connecting rods 2 at the bottom of the four movable platform parts are respectively attached to four first connecting rods 1 around the fixed platform in a one-to-one correspondence manner, and a ninth connecting rod 9 at the top of the four movable platform parts gathers towards the center. The second connecting piece 33 is jointly fixed through the connecting grooves of the four ninth connecting rods 9 and serves as a movable platform of the whole micro parallel robot. In the present invention, the second insertion piece 33 is used for mounting a device that needs to be driven later, such as a blade, a micro camera, an injection needle, a lens, a suction cup, etc. The number of second inserting pieces 33 is selected according to the equipment condition to be installed, so as to ensure stability and control accuracy. In the embodiment of the invention, two inserting grooves are arranged on each ninth connecting rod 9 at intervals, two corresponding second inserting pieces 33 are arranged and are inserted and fixed on the four ninth connecting rods 9 in parallel, and the two second inserting pieces 33 are provided with mounting pieces for being matched with equipment to be driven. The mounting member may be a mounting hole, or may be other fastening and sleeving structures, which is not limited thereto.

In the embodiment of the invention, all connecting rods forming the miniature parallel robot are processed by adopting composite lamellar materials. The middle layer of the composite lamellar material is a flexible plane material layer, two sides of the middle layer are hard plane material layers, the flexible plane material layers and the hard plane material layers are fixedly bonded through bonding material layers, two adjacent connecting rods keep the flexible plane material layers at a common hinge position continuously and the hard plane material layers are disconnected, and edges of the hard plane material layers at two sides of the disconnected position are respectively provided with rectangular grooves at intervals and are mutually embedded through saw-tooth type edges formed by the rectangular grooves, so that the flexible plane material layers can freely rotate around the common hinge under the connection effect of the flexible plane material layers.

The composite layered material can be formed into an intelligent composite material in a multi-layer composite plane structure by carrying out planarization processing on the plane material and combining with an adhesive manufacturing procedure. In the composite laminar material, the middle layer is a flexible plane material layer, the two outermost sides are hard plane material layers, and the flexible plane material layer and the hard plane material layer are fixed through an adhesive material layer. Hard planar materials include, but are not limited to: rigid metal sheets, rigid plastic sheets, rigid glass sheets, rigid resin sheets, rigid wood sheets, rigid composite sheets (e.g., rigid carbon fiber sheets), and the like, flexible planar materials including, but not limited to: flexible high molecular polymer film, flexible gel layer, flexible woven cloth, flexible metal foil, etc. The adhesive material layer can be in the form of adhesive, glue or hot-pressed adhesive tape. After the composite laminar material is subjected to planarization processing, the hard plane material layers in the intelligent composite material are clamped by the flexible plane material layers, the hard plane material layers at the two sides can be broken linearly at the joint position, the flexible plane material layer in the middle still keeps continuous, and a linear rotating shaft, namely the public hinge, can be formed. The linear rotating shaft is a linear rotating mechanism connected through flexible planar material layers, and the hard planar material layers on two sides can be utilized to rotate along the linear rotating shaft after being subjected to planarization processing and segmentation, so that the degree of freedom of motion is obtained, and the degree of freedom of rotation required by the robot joint is formed. Since the hard planar material layers on each side of the flexible planar material layer are engaged by serrations at the articulation positions, there is no translational degree of freedom between the two, but the rotational degree of freedom of the wound rotary shaft is not affected. Based on the connecting rod component formed by processing the intelligent composite material, the motion freedom degree of the device can be further designed in a three-dimensional mode according to requirements, and different actuation functions are further achieved.

In the present invention, the micro parallel robot is controlled by driving a transmission mechanism.

The power input required for controlling the micro parallel robot is transmitted through the first link 1. Under the condition that the fixed platform is fixed, the four-degree-of-freedom control of the movable platform, namely the second inserting piece 33, in the working space of the micro parallel robot can be realized by performing angle control on the 4 first connecting rods 1. The angle control can adopt various common driving modes according to working conditions and precision requirements, for example: piezoelectric ceramic drive, motor drive, wire drive, electromagnetic drive, friction drive, shape memory alloy drive, flexible material deformation drive, and the like. The invention adopts motor drive and mechanical parallel four-bar transmission as realization modes.

As shown in fig. 11, an assembly schematic diagram of a micro parallel robot and a driving transmission mechanism thereof is shown, the driving transmission mechanism comprises four sub-driving mechanisms installed on a base 48, the four sub-driving mechanisms are in one-to-one correspondence to drive four branched chains of the micro parallel robot, each sub-driving mechanism comprises a first driving connecting rod 35, a second driving connecting rod 37, a third driving connecting rod 39 and a driving motor 40, an output shaft of the driving motor 40 is fixed with one end of the third driving connecting rod 39 and forms transmission, the other end of the third driving connecting rod 39 is hinged with one end of the second driving connecting rod 37, the other end of the second driving connecting rod 37 is hinged with one end of the first driving connecting rod 35, the other end of the first driving connecting rod 35 is fixedly connected with a first connecting rod 1 in the driven branched chains, and the first driving connecting rod 35, the second driving connecting rod 37 and the third driving connecting rod 39 form parallel four-bar transmission, so that the rotation angle output by the driving motor 40 is transferred to the first connecting rod 1 of the micro parallel robot in equal proportion.

In each sub-driving mechanism of the driving transmission mechanism, parallel four-bar transmission is a key for ensuring that the micro parallel robot can realize accurate motion control. In an embodiment of the invention, the parallel four-bar transmission is designed by controlling the length of each drive link, in particular: the driving arm of the first driving link 35 is parallel to the first link 1, the first driving link 35 and the second driving link 37 are hinged through a first bearing 36, the second driving link 37 and the third driving link 39 are hinged through a second bearing 38, and the distance from the output shaft of the driving motor 40 to the second bearing 38 is equal to the distance from the first bearing to the first common hinge corresponding to the current sub-driving mechanism, and the distance from the first bearing 36 to the second bearing 38 is equal to the distance from the output shaft of the driving motor 40 to the first common hinge corresponding to the current sub-driving mechanism.

In addition, in the embodiment of the invention, a manufacturing method of the four-degree-of-freedom micro parallel robot is also provided, which comprises the following steps:

s1, integrally arranging four fixed platform parts of four branched chains on a first drawing to serve as parallel processing objects, integrally arranging four movable platform parts of four branched chains on a second drawing to serve as parallel processing objects, and processing flexible plane material layers, hard plane material layers and bonding material layers corresponding to the four fixed platform parts and the four movable platform parts layer by layer according to the two drawings; and in each material layer after processing, the area of each connecting rod needs to be temporarily connected with the plate substrate.

It should be noted that, the first drawing and the second drawing are all drawing sets, each material layer needs to be correspondingly designed to a corresponding drawing, and the material layers of the same connecting rod in all the drawings need to be correspondingly positioned, so that corresponding connecting rod components can be formed after subsequent superposition and assembly.

S2, sequentially superposing and assembling the material layers obtained by processing according to the first drawing to form a first plate with four fixed platform parts, sequentially superposing and assembling the material layers obtained by processing according to the second drawing to form a second plate with four movable platform parts, removing all temporary connections on the first plate and the second plate, and separating the four fixed platform parts and the four movable platform parts from the plate substrate respectively by cutting.

It should be noted that the temporary connection may be disposed on the drawing at the design stage of the drawing, so as to facilitate subsequent processing. The form of temporary connection is not limited and may generally be achieved by leaving a narrower rectangular connection area in the material layer.

S3, arranging first inserting pieces 32 and second inserting pieces 33 required by the four branched chains on a third drawing, processing the flexible flat material layer, the hard flat material layer and the adhesive material layer by layer according to the third drawing, sequentially stacking the processed material layers, and then separating all the first inserting pieces 32 and the second inserting pieces 33 from the plate substrate by cutting.

In the present invention, the first insertion piece 32 and the second insertion piece 33 each have a plurality of pieces, and theoretically, the pieces can be processed separately, but a parallel processing method is preferable. In the embodiment of the present invention, all the first insertion pieces 32 and the second insertion pieces 33 required on the four branches may be arranged on the same drawing sheet as parallel processing objects, and then processed in the same manner as the aforementioned connecting rod.

S3, assembling the four fixed platform parts and the four movable platform parts in a one-to-one correspondence manner to form four branched chains, splicing the four fixed platform connecting rods 0 at the bottoms of the four branched chains through male and female heads to form a complete fixed platform, simultaneously installing all the first inserting pieces 32 on each pair of sixth connecting rods 6 of the four branched chains in an inserting manner, and installing the second inserting pieces 33 on the four ninth connecting rods 9 at the tops of the four branched chains in an inserting manner to serve as a movable platform of the whole micro parallel robot.

S4, respectively installing one sub-driving mechanism on the four first connecting rods 1 of the miniature parallel robot, and fixedly installing the four sub-driving mechanisms into the base 48, so that interference between the four sub-driving mechanisms and the base 48 in the working process is avoided, and the manufacturing of the miniature parallel robot with four degrees of freedom is completed.

In order to ensure miniaturization of the drive transmission mechanism, in the embodiment of the present invention, the drive motor 40 is implemented using a micro servo motor.

In addition, the inverse kinematics of the four-degree-of-freedom Micro parallel robot Micro-X4 of the present invention has a certain similarity to that of the conventional X4 mechanism, but differs therefrom in that the two revolute pairs of the robot arm comprise a parallel four-bar mechanism, the so-called R (Pa) R arm. In the traditional robotics industry, such structures are typically manufactured from gimbals or ball pairs with constraints in order to ensure axis uniformity. However, due to the design of the planarization technology, the motion pairs on the branched chains have offset, and the offset between the parallel four-bar mechanism and the adjacent rotating pairs thereof causes the difference of Micro-X4 and traditional X4 kinematics.

Therefore, in an embodiment of the present invention, there is also provided a control method of the four-degree-of-freedom micro parallel robot, including the steps of:

Wherein: ^G R _P is a transformation matrix of a coordinate system from a fixed platform coordinate system { G } to a movable platform coordinate system { P }, and a line vector P _i ＝[rcosβ _i ,rsinβ _i ,-h]Angle beta _i For i=1, i=2, i=3, i=4, 60 °, 120 °, 240 °, 300 °, r is the distance from the center of the second insertion tab 33 to the center line of the insertion slot, h is the length of the eighth link 8; normal vector s= [ -sin alpha _i ,cosα _i ,0]Angle alpha _i Taking 0 ° 90 ° 180 ° 270 ° for i=1, i=2, i=3, i=4, respectively;is the length of the fifth connecting rod 5;

s2, according to the cos gamma of each branched chain _i Calculating the angle theta of the output required by the drive motor 40 in the sub-drive mechanism to which the ith branch is connected _i The calculation formula is:

wherein: zeta type toy ₁ ＝[1,0,0] ^T ，ξ ₂ ＝[0,1,0] ^T ，ξ ₃ ＝[0,0,1] ^T The method comprises the steps of carrying out a first treatment on the surface of the Vector b _i ＝[Rcosα _i ,Rsinα _i ,0]R is the distance from the center of the fixed platform to the first common hinge; length ofL ₁ For the length of the first connecting rod 1, L ₂ For the length of the second link 2, _s a thickness of the composite layered material;

s3, according to the angle theta of the required output of the driving motor 40 in the sub-driving mechanism connected with each branched chain _i A control command is issued to the corresponding driving motor 40, and each driving motor 40 is further driven to output a corresponding angle theta _i The center point P of the movable platform reaches the target position.

Finally, the intelligent composite material manufactured by planarization and the parallel four-bar transmission mode can finally realize the volume of 3.7cm multiplied by 2.8cm and the working space of 810mm based on the specific control method ³ The working frequency is 50Hz, the repeated positioning precision is 20um, and the miniature parallel robot with four degrees of freedom of translation along the X, Y, Z axis and rotation along the Z axis is provided.

For further understanding, the present invention further illustrates the design, fabrication and control process of the four-degree-of-freedom Micro parallel robot Micro-X4 described above by way of a specific preferred example.

Examples

In the preferred example, the four-degree-of-freedom Micro parallel robot Micro-X4 is made of intelligent composite materials, and the design and manufacturing flow is divided into 4 steps, namely: 1. and (3) plane dimension design, 2, layering design, 3, intelligent composite material production, and 4, splicing assembly. Wherein the planarization design step determines the geometric features of the robot; the layering design step is complementary process design which is performed on the basis of the first-step planarization design in order to meet the processing requirement of the intelligent composite material; the intelligent composite material production step is to obtain all components forming the robot by processing and bonding the soft and hard plates according to the processing drawing generated in the second step; the plugging assembly step is to assemble the components produced in the third step and obtain the final four-degree-of-freedom miniature parallel robot.

The first step: planar dimension design

The four-degree-of-freedom miniature parallel robot has central rotational symmetry, can be assembled by splicing 4 branched chains with similar shapes, and each branched chain is divided into a fixed platform and a movable platform. Fig. 2 is a plan view of the above-mentioned branched chain, in which the left side is a fixed platform portion, the right side is a movable platform portion, the solid line is a contour line of a robot part, and the broken line is a flexible hinge. The connecting rod assembly relationship of the micro parallel robot is as described above and will not be described again.

In fig. 2, the serial numbers and main design parameters of the parts involved in the micro parallel robot are marked: the fixed platform connecting rod 0 is a fixed platform of the robot 1/4 and is marked with a fixed platform radius R1, and the fixed platform is distributed at an angle gamma 1; the length of the connecting rod 1 is L1, and the width is W1; the length of the connecting rod 2 is L2, the width of the connecting rod is W2, the length of the connecting rod 3 is L3, and the width of the connecting rod is W3; the length of the connecting rod 4 is L4, and the width is W4; the length of the connecting rod 5 is L5, and the width W5; the length L6 and width W6 (not shown) of the link 6 generally correspond to the link 4; the length of the connecting rod 7 is L7, and the width is W7; the length of the connecting rod 8 is L8, and the width is W8; the length of the connecting rod 9 is L9, the width of the connecting rod 9 is W9, the width of the inserting groove is J1, and the depth of the inserting groove is J2.

The values of the above parameters can be chosen arbitrarily under the condition that the geometric closure can be achieved, and in this example, the following parameters are preferred for the purpose of taking into account the small robot volume and the large working space volume: r1=6 mm, γ1=45°, l1=12.5 mm, w1=6 mm, w2=6 mm, l2=4.5 mm, w2=6 mm, l3=4 mm, w3=5 mm, l4=2.8 mm, w4=4.6 mm, l5=13 mm, w5=3.6 mm, l6=2.8 mm, w6=w4, l7=4 mm, w7=5.5 mm, l8=6.8 mm, w8=2.5 mm, l9=5.6 mm, w9=3 mm, j1=0.5 mm, j2=1.2 mm.

The dashed lines in fig. 2 represent the flexible common hinge, and to increase the rigidity of the hinge, rectangular grooves must be etched in the rigid material to allow the rigid parts to engage with each other as they rotate about the flexible hinge, which engagement may increase the rigidity of the hinge.

The dimensions of the rectangular grooves are shown in fig. 3, labeled with the groove length CL and the groove width CW. The length CL of the rectangular groove is determined by the thickness of the rigid material and the rotation angle range of the hinge, and is within 3 times of the thickness of the rigid material, and generally 1 time of the thickness of the rigid material. The width CW of the rectangular slot is determined by the thickness of the rigid material, the hinge length, the machining precision, etc., and has a value greater than 1/3 of the thickness of the rigid material and less than 1/3 of the hinge length. In this example, cl=0.55 mm and cw=0.2 mm are preferably taken.

The remaining three branches are similar in shape to the branches described above and will be shown in detail in the next step.

And a second step of: hierarchical design

As shown in fig. 4, due to the processing and manufacturing requirements of the intelligent composite material, in order to facilitate the subsequent bonding process and ensure the processing precision, the relative positions of all parts of the micro-robot should be fixed during the processing of the plate without being separated from the plate. To meet the above-mentioned process requirements, a complementary design is required for the design drawing, and the design drawing on the left side of fig. 4 adds a temporary connection design of the parts and the board on the basis of fig. 2, which may be called "island chain" in this example. These islands are separated in the figure by pairs of dashed lines, which are broken along the dashed lines after the bonding process is completed to free the formed smart composite member from the sheet. The white portion of the three right-hand side of the figure shows the sheet that has been removed, the shaded fill shows the parts remaining after processing, and all parts can be seen connected to the sheet base by island chains.

For convenience of description, in this example, the length of the broken line is defined as the length DL of the island chain, and the pitch of the paired broken lines is defined as the width DW of the island chain. The island chain length DL is chosen to be determined by the strength, thickness and part geometry of the rigid material and is typically greater than 1/5 of the length of the part being joined. The width of the island chain is selected to facilitate processing and is generally less than the maximum feature size of the connected parts.

Fig. 5 is a design drawing of 4 branches required for producing a four-degree-of-freedom micro parallel robot, wherein the upper side is a movable platform part, and the lower side is a fixed platform part. It can be seen that the 4 similar branches constituting the micro parallel robot are identical in pairs, namely, the branch 10 is identical to the branch 11, and the branch 12 is identical to the branch 13. Two differences exist between different branched chains, the first difference is that the shapes of the splicing structures of the two branched chain fixed platform connecting rods 0 are complementary to form a male head and a female head, and the second difference is that the two branched chains are mirror symmetry except the first difference and the hinge grooves.

And a third step of: intelligent composite material production

Fig. 6 is a drawing of a four-degree-of-freedom micro parallel robot production process with the broken lines for freeing the robot from the sheet substrate hidden on the basis of fig. 5. The drawing No. 14 is used for processing the upper rigid layer material and the upper bonding layer material of the movable platform, the drawing No. 15 is used for processing the upper rigid layer material and the upper bonding layer material of the fixed platform, the drawing No. 16 is used for processing the lower rigid layer material and the lower bonding layer material of the movable platform, the drawing No. 17 is used for processing the lower rigid layer material and the lower bonding layer material of the fixed platform, the drawing No. 18 is used for processing the intermediate layer flexible layer material of the movable platform, the drawing No. 19 is used for processing the intermediate layer flexible layer material of the fixed platform, and the drawing No. 20 is used for processing the bonding layer material for bonding the fixed platform layer and the movable platform layer. In the drawings, the drawing No. 14 and the drawing No. 16 are respectively corresponding to the upper layer and the lower layer, the drawing No. 15 and the drawing No. 17 are respectively corresponding to the upper layer and the lower layer, and the differences are that the hinge grooves are symmetrical about the center line of the hinge, the enveloping relation of the male head and the female head and the direction marks on the right side.

Fig. 7 is a flow chart of actual production of the four-degree-of-freedom micro parallel robot, and the processing flow is as follows: a. sequentially bonding a No. 21 material (upper rigid layer material), a No. 23 material (middle flexible layer material) and a No. 25 material (lower rigid layer material) by using a No. 22 material (upper bonding layer material), a No. 24 material (lower bonding layer material); b. machining the required parts from the plate substrate along the broken lines; c. obtaining a robot moving platform with only the tail end fixed with the plate substrate; d. sequentially bonding a No. 26 material, a No. 28 material and a No. 30 material by using a No. 27 material and a No. 29 material; e. machining the required parts from the plate substrate along the broken lines; f. a robot stator platform is obtained with only the ends fixed to the plate substrate. Material No. 21, material No. 22 in sub-graph a of fig. 7 correspond to drawing No. 14 in fig. 6, material No. 23 corresponds to drawing No. 18 in fig. 6, and material No. 24, sheet material No. 25 corresponds to drawing No. 16 in fig. 6. Material No. 26, material No. 27 correspond to drawing No. 15 in fig. 6, material No. 28 corresponds to drawing No. 19 in fig. 6, material No. 29, material No. 30 corresponds to drawing No. 17 in fig. 6 in sub-panel b.

In fig. 8, the movable platform layer and the fixed platform layer obtained in the processing flow of fig. 7 are connected by an adhesive material, and then the complete branched chain is released from the material substrate along the above-mentioned broken line processing. a. Connecting a movable platform layer and a fixed platform layer shown in a sub graph c and a sub graph f in FIG. 7 through a No. 31 material; b. releasing the bonded branches from the material substrate along the broken line; c. removing the branched chain state after all island chains; d. and separating the complete branched chain from the material substrate, and completing the processing steps of the miniature parallel robot.

In the example, the hard planar material is 500-micron-thick twill bidirectional weaving carbon fiber, the soft planar material is 50-micron-thick polyimide film, the soft planar material and the hard planar material are bonded through a 13-micron-thick hot-pressing adhesive tape, the auxiliary piece material is 500-micron-thick alumina ceramic, and the processing mode is high-precision laser ablation processing.

Fourth step: plug-in assembly

In fig. 9, sub-graph a is a plug-in piece 32 of a parallel four-bar micro parallel robot, and main design parameters required by the plug-in piece design are marked: the length of the inserting piece is L32, the width of the inserting piece is W32, the interval of inserting grooves is J3, the width of the inserting grooves is J4, and the depth of the inserting grooves is J5. Wherein J3 is equal to W3; the J4 value is determined by the selected materials, the thickness of the hard material in the 5-layer structure of the intelligent conforming material is T1, the thickness of the bonding material is T2, and the thickness of the soft material is T3, then J4=2× (T1+T2) +T3; the length of J5 is less than W9-J2.

In fig. 9, sub-graph b is a plug 33 forming a movable platform of the micro-parallel robot, the reference radius of the plug of the movable platform is R2, the distribution angle of the rotating shaft of the movable platform is γ2, the distribution angle of the plug groove is γ3, the distance from the rotating shaft to the bottom of the plug groove is DL, the length of the plug is L33, the width of the plug groove is J5, the depth of the plug groove is J6, the boundary width of the plug area is J7, the width of the plug area is W33, and two process fillets DR1 and DR2 are further included.

The plug-in piece 33 is divided into two areas, the areas contained in the two parallel lines with the interval L33 are non-plug-in areas, the rest is plug-in areas, and the 4 plug-in areas respectively contain one plug-in groove. In the notation shown in fig. 9, subplot b: r2 and gamma 2 determine the distribution of the rotating shafts of the movable platform, and the corresponding hinges of the rotating shafts belong to a connecting rod 8 and a connecting rod 9; gamma 3 determines the opening direction of the inserting groove; the distance from the rotating shaft to the bottom of the plugging groove is DL, and the value of the distance is determined by a connecting rod 9 and is equal to W9-J2; l33 determines the area of the non-plugging area and the rotating range of the movable platform; the width J5 of the inserting groove is determined by the thickness of 5 layers of intelligent composite materials; j6, determining the plugging depth so as to influence the strength of plugging fit; j7 affects the strength of the mating zone; w33 is the width of the plug area, the value of which affects the strength of the plug area.

The values of the above parameters can be chosen arbitrarily under the condition that the geometric closure can be achieved, and in this example, the following parameters are preferred for the purpose of taking into account the small robot volume and the large working space volume: l32=3.7mm, w32=8.5mm, j3=5 mm, j4=1.1mm, j5=2 mm, r2=5 mm, γ2=60°, γ3=90°, dl=1.8mm, l33=4.2mm, j5=1.1mm, j6=1.07 mm, w33=2.68 mm, j7=1 mm, dr1=2.8 mm, dr2=0.5 mm.

Fig. 10 shows a plugging assembly flow of the micro parallel robot. As shown in the sub-graph a, the branched chain is rotated by 90 degrees along the common hinge of the connecting rod 3 and the connecting rod 4 and the symmetrical hinge thereof, and then rotated by 90 degrees along the common hinge of the connecting rod 6 and the connecting rod 7 and the symmetrical hinge thereof, so that the connecting rod 4, the connecting rod 5, the connecting rod 6 and the symmetrical connecting rod thereof are perpendicular to the connecting rod 3 and the connecting rod 7 to form a parallel four-rod structure, and four shafts of the parallel four rods are the rotating shafts. As shown in sub-graph b, the 32-number plug connector is respectively inserted into the plug grooves formed in the connecting rod 4 and the symmetrical connecting rod thereof and the plug grooves of the connecting rod 6 and the symmetrical connecting rod thereof along the direction indicated by the arrow, and the parallel four-bar structure is fixed through plug fit. As shown in sub c, the male heads and the female heads of the four branched chains are inserted and fixed (described in the second step of the production step), and the specific structures of the male heads and the female heads are shown as a plate 15 and a plate 17 in fig. 6. As shown in sub-figure d, two 33-piece connectors are inserted into the inserting grooves formed in the connecting rod 9 along the direction indicated by the arrow. As shown in sub e, the 4 branched chains are matched with the 33 # plug pieces in a plug-in manner through the male and female connectors to complete the sealing, and the miniature parallel robot is in a finished structure.

The power input required for controlling the micro parallel robot is transmitted through the connecting rod 1. Under the condition that the fixed platform (formed by splicing fixed platform connecting rods 0) is fixed, the four-degree-of-freedom control of the movable platform (splicing piece 33) in the working space of the miniature parallel robot can be realized by performing angle control on the 4 connecting rods 1. The angle control can adopt various common driving modes according to working conditions and precision requirements, for example: piezoelectric ceramic drive, motor drive, wire drive, electromagnetic drive, friction drive, shape memory alloy drive, flexible material deformation drive, and the like. This example uses a motor drive and a mechanical parallel four bar drive as the demonstration.

Fig. 11 shows a micro parallel robot and its drive transmission system. The sub-graph a of fig. 11 is a transmission schematic diagram, and the motor angle α is set to 1 by using the principle of parallel four-bar opposite side parallelism: the ratio 1 is transmitted to the miniature parallel robot connecting rod 1. The length of the driving arm of the connecting rod 1 is L1, the length of the motor driving arm is L3, L1=L3, the distance between the two rotating supports is L2, and the length of the connecting rod connecting the driving arm of the connecting rod 1 and the motor driving arm is L2.

Drawing b of fig. 11 is an assembly drawing of a driving system for connecting the micro parallel robot and the motor, in which No. 34 is the micro parallel robot, no. 35 is the No. 1 driving link, no. 36 is the No. 1 bearing, no. 37 is the No. 2 driving link, no. 38 is the No. 2 bearing, no. 39 is the No. 3 driving link, and No. 40 is the small-sized servo motor. The No. 1 driving connecting rod is connected with a connecting rod 1 of the miniature parallel robot; the No. 1 bearing is arranged in the No. 1 driving connecting rod along the arrow direction; the second driving connecting rod is respectively provided with a bearing No. 1 and a bearing No. 2 along the arrow direction; and a No. 3 driving connecting rod is arranged in the No. 2 bearing along the arrow direction, and the No. 3 driving connecting rod is connected with the small-sized servo motor.

Drawing c of fig. 11 shows the above-mentioned assembly connection of the driving system, with No. 41 being a No. 1 bolt, no. 42 being a No. 1 nut, and No. 43 being a No. 2 bolt. The No. 1 driving connecting rod and the miniature parallel robot connecting rod 1 are fixed by matching the No. 1 bolt and the No. 1 nut; and the No. 2 bolt is matched with the threaded hole on the motor to fix the No. 3 fixed connecting rod and the motor. The effect after the assembly connection is shown in sub-graph d. Sub-graph e of fig. 11 is a front view of sub-graph d, and L1, L2, L3, α marked in sub-graph e correspond to the transmission schematic diagram shown in sub-graph a.

Subimage f of fig. 11 is a schematic diagram of the process of loading the micro parallel robot, drive system, and motor into the base, wherein a portion of the links are hidden for ease of viewing. The number 44 of the pieces shown in the figure is a number 3 bolt, the number 45 of the pieces is a number 4 bolt, the number 46 of the pieces is a robot base, the number 47 of the pieces is a stand column, the number 48 of the pieces is a base, the number 49 of the pieces is a number 1 gasket, and the number 50 of the pieces is a number 5 bolt. The No. 3 bolt passes through a round hole on the fixed platform along the direction indicated by an arrow and is matched with a threaded hole on the robot base to fix the miniature parallel robot on the robot base; the No. 4 bolt is placed into a counter bore on the robot base along the direction indicated by the arrow and matched with a hole at the top of the upright post to fix the robot base on the upright post; the No. 5 bearing passes through the No. 1 gasket along the direction indicated by the arrow and is placed into the counter bore of the base to be matched with the threaded hole at the bottom of the upright post so as to fix the upright post on the base. Drawing g of fig. 11 is a schematic diagram of the result of completing the assembly process described above.

Drawing h of fig. 11 is a schematic flow chart of fixing the small-sized servo motor to the base. The 51 pieces are washers 2 and the 52 pieces are bolts 6. The No. 6 bolt passes through the No. 2 gasket along the direction indicated by the arrow and is matched with the hole of the side plate of the base and the bolt hole on the motor to fix the motor on the base. Sub-graph i is a schematic diagram of the result of completing the assembly process.

In addition, FIG. 12 shows a comparison of the four degree of freedom Micro-robot Micro-X4 of the present invention with a conventional X4 geometric model, wherein (a) the conventional X4 geometric model..b) the process of the present invention produces a Micro-X4 geometric model containing a paranoid (C.) point C _i With GA _i B _i The angle gamma between the faces _i Resulting deviation d _γi

The inverse kinematics of Micro-X4 are similar to that of the traditional X4 mechanism, but are modified. The robot arm comprises a parallel four-bar mechanism between two rotating pairs, namely a so-called R (Pa) R arm. In the traditional robotics industry, such structures are typically manufactured from gimbals or ball pairs with constraints in order to ensure axis uniformity. To adapt the SCM method to such complex closed-chain 4 degree of freedom drives, we have adopted a break-recombination approach to enable it to be manufactured by planarization processes. Because of the design requirement of the planarization process, the motion pairs on the branched chains are offset, and the offset between the parallel four-bar mechanism and the adjacent rotating pairs thereof causes the difference between Micro-X4 and traditional X4 kinematics. Here we first demonstrate the inverse kinematics of the traditional X4 structure and then perform an inverse kinematics analysis on the biased Micro-X4.

For conventional X4, its geometry is shown as sub-graph (a) in fig. 12. The fixed platform coordinate system and the movable platform coordinate system are respectively defined as { G } and { P }. The center point of the movable platform is P. To solve for the inverse kinematics, the pose of the point P in { G } is given in the figure, i.e. the spatial position vector t= (x, y, z) ^T And an angle alpha. In the following derivation, vectors and matrices are represented in bold, and scalars are represented in plain. Solving the input angle theta of each branched chain by the inverse kinematics solving target of the X4 mechanism under the condition that t is known _i . The principle of the solution is briefly described below for easy understanding.

First, for branch i, its closed-chain equation can be written as:

t+ ^G R _P p _i ＝b _i +L ₁ m _i +L ₂ n _i (1)

wherein t= (x, y)，z) ^T Is the spatial position vector of point P in { G }, P _i Is PC (personal computer) _i Line vector in { P }, P _i ＝[rcosβ _i ，rsinβ _i ，-h]R corresponds to the dimension R2 in FIG. 9, h is a branch C _i D _i Corresponding to the dimension L8 in figure 2, ^G R _P is a conversion matrix of a coordinate system from { G } to { P }, b _i Is GA _i Line vector, b described under coordinate system { G } _i ＝[Rcosa _i ，Rsina _i ，0]With alpha to the current branch i _i ＝0，L ₁ Is a branched chain A _i B _i Length L of (2) ₂ Is the length of the parallel four bars BiCi, corresponds to the dimension L5, m in FIG. 2 _i Is a connecting rod A _i B _i Unit vector, m _i ＝ ^G R _A [0，0，1] ^T ＝[ca _i cθ _i ，sa _i cθ _i ，sθ _i ] ^T ，θ _i Is a connecting rod A _i B _i N, n _i Is a center line B of a parallel four-bar mechanism _i C _i Is a unit vector of (a).

To solve equation 1, first square the two sides of the equation to obtain:

by simplifying equation 2, it is possible to obtain:

equation 3 is constant on the left and trigonometric function on the right, and the entire equation can be solved by:

compared with the traditional X4, the Micro-X4 manufactured by the invention has the geometrical difference that the parallel four-bar mechanism is between the adjacent revolute pair thereof Is shown (sub-graph b in fig. 12). These two biases B _i X _1i And X is _2i C _i Having the same unit vector n _ii The sum of their lengths is d, corresponding to the dimension L3+L7 in FIG. 2, so the closed-chain equation 1 for the branches can be written as:

in the middle ofIs a central line X of a parallel four-bar mechanism ₁ X ₂ Length n of (2) _i Is X ₁ X ₂ The definition of the other symbols is the same as that of formula 1.

Let b in equation 5 _i Andtwo terms are moved to the left side, and square is carried out on two sides, so that the following steps are obtained:

the above equation has two additional terms compared to equation 2: d, d ² Andwherein->Is an unknown item.

Due to n _i And n _ii Respectively X _1i X _2i And B is connected with _i X _1i So there are:

n _i ·n _ii ＝cosγ _i (7)

wherein gamma is _i Is X _1i X _2i Rotation angle with respect to the rectangle. Equation 6 can be written as:

thus, can pass through GA _i B _i Surface to solve for gamma _i . Let s be the face GA _i B _i Normal vectors in the coordinate system { G }, there are:

s＝[-sinα _i ，cosα _i ，0]. (10)

let d _γi For point C _i To the surface GA _i B _i Deviation of d _γi Can be expressed as:

it can be seen that the deviation d _γi By X only _1i X _2i Is rotated by an angle of rotation gamma _i Causing. Thus the deviation d _γi Can be written as:

thus sin gamma _i And cos gamma _i Can be solved, i.e., equation 9 can be solved. Therefore, the inverse kinematics solution theta of the four branches of the Micro-X4 robot can be solved by rotationally adjusting the position of each branch in space _i 。

Based on the above principle description, the geometric structure shown in fig. 12 is specifically corresponding to the Micro-X4 robot of the entity, so as to obtain the control method adopted in the example, which is specifically as follows:

wherein: ^G R _p is a transformation matrix of a coordinate system from a fixed platform coordinate system { G } to a movable platform coordinate system { P }, and a line vector P _i ＝[rcosβ _i ，rsinβ _i ，-h]Angle beta _i For i=1, i=2, i=3, i=4, 60 °, 120 °, 240 °, 300 °, r is the distance from the center of the second insertion tab 33 to the center line of the insertion slot, h is the length of the eighth link 8; normal vector s= [ -sin alpha _i ，cosα _i ，0]Angle alpha _i Taking 0 ° 90 ° 180 ° 270 ° for i=1, i=2, i=3, i=4, respectively;is the length of the fifth connecting rod 5;

wherein: zeta type toy ₁ ＝[1，0，0] ^T ，ξ ₂ ＝[0，1，0] ^T ，ξ ₃ ＝[0，0，1] ^T The method comprises the steps of carrying out a first treatment on the surface of the Vector b _i ＝[Rcosα _i ，Rsinα _i ，0]R is the distance from the center of the fixed platform to the first common hinge; length ofL ₁ For the length of the first connecting rod 1, L ₂ Is the length d of the second connecting rod 2 _s A thickness of the composite layered material;

Fig. 13 is a schematic view showing the control of the pose of the movable platform of the micro-robot by changing the rotation angle of the motor. An acute angle between a plane formed by a rotation axis between the fixed platform connecting rod 0 and the connecting rod 1 and a rotation axis between the connecting rod 2 and the connecting rod 3 and a fixed platform plane formed by the fixed platform connecting rod 0 is defined as an input angle. The sub-graph a of fig. 13 shows the pose of the moving platform when the input angles of the connecting rods are all 0 degrees, the fixed platform coordinate system is taken as a reference, the position vectors of the characteristic points of the moving platform are (0, 24.585), the units are millimeters, and the rotation angle is 90 degrees; drawing b shows that the input angle of the connecting rod I is-3.3049 degrees, the input angle of the connecting rod II is-0.4842 degrees, the input angle of the connecting rod III is 3.6713 degrees, the input angle of the connecting rod IV is 1.1 degrees, a fixed platform coordinate system is taken as a reference, at the moment, the position vector of the characteristic point of the movable platform is (1, 0, 24.585), the unit is millimeter, and the rotation angle is 45 degrees; drawing c shows that the input angle of the No. I connecting rod is-0.2967 degrees, the input angle of the No. II connecting rod is 11.9128 degrees, the input angle of the No. III connecting rod is 7.0219 degrees, the input angle of the No. IV connecting rod is 17.2524 degrees, a fixed platform coordinate system is taken as a reference, at the moment, the position vector of the characteristic point of the movable platform is (1, 0, 24.585), the unit is millimeter, and the rotation angle is 90 degrees.

Fig. 14 is a diagram showing a comparison between actual moving platform trajectory data and theoretical trajectory data obtained by controlling the rotation of a motor through trajectory planning of a micro parallel robot moving platform. It can be seen from the data that the micro parallel robot has a repeated positioning accuracy higher than 20um and an absolute positioning accuracy of 200 um.

The miniature parallel robot can carry different equipment to face various working conditions by carrying out shape design on the non-plug-in area of the plug-in sheet 33. For example: the blade, the miniature camera, the injection needle, the lens, the sucker and the like can enable the robot to complete various tasks such as cutting, positioning photography, puncture injection, laser control, adsorption grabbing and the like. In this example, 3 embodiments of the blade, the injection needle and the suction cup are illustrated in fig. 15. In the sub-graph a of fig. 15, a movable platform pinboard required for implementing the cutting task is listed, and a miniature parallel robot model with a mounted blade is attached; in fig. 15, sub-view b, a movable platform pinboard required for performing the puncture task is listed, and a micro parallel robot model after installing an injection needle is attached; in fig. 15, sub-graph c, a movable platform pinboard required for performing the suction gripping task is listed, and a micro parallel robot model with suction cups is attached.

The above embodiment is only a preferred embodiment of the present invention, but it is not intended to limit the present invention. Various changes and modifications may be made by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present invention. Therefore, all the technical schemes obtained by adopting the equivalent substitution or equivalent transformation are within the protection scope of the invention.

Claims

1. The four-degree-of-freedom miniature parallel robot is characterized by comprising the miniature parallel robot and a driving transmission mechanism;

the fixed platform part comprises a fixed platform connecting rod (0) and a first connecting rod (1), and the fixed platform connecting rod (0) is connected with the first connecting rod (1) through a first common hinge; four fixed platform connecting rods (0) in the four branched chains are spliced through male and female heads to form a complete fixed platform;

the movable platform part comprises a second connecting rod (2), a third connecting rod (3), a fourth connecting rod (4), a fifth connecting rod (5), a sixth connecting rod (6), a seventh connecting rod (7), an eighth connecting rod (8) and a ninth connecting rod (9); the second connecting rod (2) is connected with the third connecting rod (3) through a second common hinge; the four connecting rods (4) are symmetrically distributed on two sides of the third connecting rod (3) and are respectively connected with the third connecting rod (3) through a third common hinge; the two fifth connecting rods (5) are symmetrically arranged on the sides of the two fourth connecting rods (4), and the two fifth connecting rods (5) are respectively connected with the two fourth connecting rods (4) through fourth common hinges; the six connecting rods (6) are symmetrically arranged on the sides of the two fifth connecting rods (5), and the six connecting rods (6) are respectively connected with the two fifth connecting rods (5) through fifth common hinges; the seventh connecting rod (7) is positioned between the two sixth connecting rods (6) and is connected with the two sixth connecting rods (6) through a sixth common hinge respectively; the four-bar linkage comprises a third connecting rod (3), a fourth connecting rod (4), a fifth connecting rod (5), a sixth connecting rod (6), a seventh connecting rod (7), another sixth connecting rod (6), another fifth connecting rod (5) and another fourth connecting rod (4) which are connected end to end, wherein the fourth connecting rod (4), the fifth connecting rod (5) and the sixth connecting rod (6) are vertical to the third connecting rod (3) and the seventh connecting rod (7) in a non-working state, inserting grooves are formed in the two fourth connecting rods (4) and the two sixth connecting rods (6), and the two fourth connecting rods (4) and the two sixth connecting rods (6) are respectively connected and sealed by inserting first inserting tabs (32) in the inserting grooves, so that a parallel four-bar structure is formed; the eighth connecting rod (8) is connected with the seventh connecting rod (7) through a seventh common hinge, a vacant area for placing the ninth connecting rod (9) is arranged in the eighth connecting rod (8), and the ninth connecting rod (9) is connected with the eighth connecting rod (8) through the eighth common hinge; the ninth connecting rod (9) is also provided with a splicing groove;

Four second connecting rods (2) positioned at the bottoms of the four movable platform parts are respectively and correspondingly attached to four first connecting rods (1) around the fixed platform one by one, and a ninth connecting rod (9) positioned at the top of the four movable platform parts gathers towards the center; the second inserting piece (33) is jointly fixed through inserting grooves of four ninth connecting rods (9) and is used as a movable platform of the whole micro parallel robot;

the driving transmission mechanism comprises four sub-driving mechanisms which are arranged on the base (48), and the four sub-driving mechanisms are in one-to-one correspondence to drive four branched chains of the micro parallel robot; each sub-driving mechanism comprises a first driving connecting rod (35), a second driving connecting rod (37), a third driving connecting rod (39) and a driving motor (40), wherein an output shaft of the driving motor (40) is fixed with one end of the third driving connecting rod (39) and forms transmission, the other end of the third driving connecting rod (39) is hinged with one end of the second driving connecting rod (37), the other end of the second driving connecting rod (37) is hinged with one end of the first driving connecting rod (35), the other end of the first driving connecting rod (35) is fixedly connected with a first connecting rod (1) in a driven branched chain, and the first driving connecting rod (35), the second driving connecting rod (37) and the third driving connecting rod (39) form parallel four-rod transmission, so that the rotation angle output by the driving motor (40) is transmitted to the first connecting rod (1) of the miniature parallel robot in an equal proportion.

2. The four-degree-of-freedom micro parallel robot of claim 1, wherein all the connecting rods constituting the micro parallel robot are processed by adopting composite layered materials, an intermediate layer of the composite layered materials is a flexible planar material layer, two sides of the intermediate layer are hard planar material layers, the flexible planar material layers and the hard planar material layers are adhered and fixed by an adhesive material layer, the flexible planar material layers are kept continuous by two adjacent connecting rods at a common hinge position, the hard planar material layers are broken, and the edges of the hard planar material layers at two sides of the broken position are provided with rectangular grooves at intervals and are mutually embedded by saw-tooth-shaped edges formed by the rectangular grooves, so that the flexible planar material layers can freely rotate around the common hinge under the connection action of the flexible planar material layers.

3. The four-degree-of-freedom miniature parallel robot according to claim 2, characterized in that two insertion grooves are formed in each ninth connecting rod (9) at intervals, two second insertion pieces (33) are inserted and fixed on the four ninth connecting rods (9) in parallel, and mounting pieces for being matched with equipment to be driven are formed in the two second insertion pieces (33).

4. Four-degree-of-freedom micro parallel robot according to claim 2, wherein in each sub-drive of the drive transmission, the drive arm of the first drive link (35) is parallel to the first link (1), the first drive link (35) and the second drive link (37) are hinged by a first bearing (36), the second drive link (37) and the third drive link (39) are hinged by a second bearing (38), and the distance from the output shaft of the drive motor (40) to the second bearing (38) is equal to the distance from the first bearing to the first common hinge corresponding to the current sub-drive, and the distance from the first bearing (36) to the second bearing (38) is equal to the distance from the output shaft of the drive motor (40) to the first common hinge corresponding to the current sub-drive.

5. The four-degree-of-freedom micro parallel robot of claim 2 wherein the drive motor (40) is a micro servo motor.

6. The four-degree-of-freedom micro parallel robot of claim 2, wherein the flexible planar material layer is a soft high molecular polymer film, a soft gel layer, a soft woven cloth, a soft metal foil; the hard flat material layer is a hard metal plate, a hard plastic plate, a hard glass plate, a hard resin plate, a hard wood plate and a hard composite material plate.

7. The four-degree-of-freedom miniature parallel robot according to claim 1, wherein two insertion grooves are formed in each ninth connecting rod (9) at intervals, two second insertion pieces (33) are inserted and fixed on the four ninth connecting rods (9) in parallel, and mounting pieces for being matched with equipment to be driven are formed in the two second insertion pieces (33).

8. Four-degree-of-freedom micro parallel robot according to claim 1, wherein in each sub-drive mechanism of the drive transmission mechanism, the drive arm of the first drive link (35) is parallel to the first link (1), the first drive link (35) and the second drive link (37) are hinged by a first bearing (36), the second drive link (37) and the third drive link (39) are hinged by a second bearing (38), and the distance from the output shaft of the drive motor (40) to the second bearing (38) is equal to the distance from the first bearing to the first common hinge corresponding to the current sub-drive mechanism, and the distance from the first bearing (36) to the second bearing (38) is equal to the distance from the output shaft of the drive motor (40) to the first common hinge corresponding to the current sub-drive mechanism.

9. The four-degree-of-freedom micro parallel robot of claim 1 wherein the drive motor (40) is a micro servo motor.

10. The four-degree-of-freedom micro-parallel robot of claim 1, wherein two of the four fixed platform links (0) have male heads and two have female heads in the fixed platform portions of the four branches, and the four fixed platform links (0) are assembled as one body through the male heads and the female heads.

11. A method of manufacturing a four-degree-of-freedom micro parallel robot according to any one of claims 2 to 6, comprising the steps of:

S3, arranging first inserting pieces (32) and second inserting pieces (33) required by the four branched chains on a third drawing, processing the flexible flat material layer, the hard flat material layer and the bonding material layer by layer according to the third drawing, sequentially stacking the processed material layers, and separating all the first inserting pieces (32) and the second inserting pieces (33) from the plate substrate by cutting;

s3, assembling the four fixed platform parts and the four movable platform parts in a one-to-one correspondence manner to form four branched chains, splicing four fixed platform connecting rods (0) at the bottoms of the four branched chains through male and female heads to form a complete fixed platform, simultaneously installing all first inserting pieces (32) on each pair of sixth connecting rods (6) of the four branched chains in an inserting manner respectively, and installing second inserting pieces (33) on four ninth connecting rods (9) at the tops of the four branched chains in an inserting manner to serve as a movable platform of the whole micro parallel robot;

s4, respectively installing one sub-driving mechanism on four first connecting rods (1) of the miniature parallel robot, and fixedly installing the four sub-driving mechanisms into a base (48), so that interference between the four sub-driving mechanisms and the base (48) in the working process is avoided, and the manufacturing of the miniature parallel robot with four degrees of freedom is completed.

12. The manufacturing method according to claim 11, wherein in S3, all the first insertion pieces (32) and the second insertion pieces (33) required on the four branches are arranged on the same drawing sheet as parallel processing objects.

13. A control method of the four-degree-of-freedom micro parallel robot according to any one of claims 1 to 10, comprising the steps of:

s1, according to the control purposeTarget, determining a target space position vector t of a moving platform center point P in a fixed platform coordinate system { G }, and calculating a rotation angle gamma of any ith branched chain _i I=1, 2,3,4, the formula is:

wherein: ^G R _P is a transformation matrix of a coordinate system from a fixed platform coordinate system { G } to a movable platform coordinate system { P }, and a line vector P _i ＝[rcosβ _i ,rsinβ _i ,-h]Angle beta _i For i=1, i=2, i=3, i=4, 60 °, 120 °, 240 °, 300 °, r is the distance from the center of the second insertion tab (33) to the center line of the insertion slot, h is the length of the eighth link (8); normal vector s= [ -sin alpha _i ,cosα _i ,0]Angle alpha _i Taking 0 ° 90 ° 180 ° 270 ° for i=1, i=2, i=3, i=4, respectively;is the length of the fifth connecting rod (5);

s2, according to the cos gamma of each branched chain _i Calculating the angle theta of the output required by the driving motor (40) in the sub-driving mechanism connected with the ith branched chain _i The calculation formula is:

wherein: zeta type toy ₁ ＝[1,0,0] ^T ，ξ ₂ ＝[0,1,0] ^T ，ξ ₃ ＝[0,0,1] ^T The method comprises the steps of carrying out a first treatment on the surface of the Vector b _i ＝[Rcosα _i ,Rsinα _i ,0]R is the distance from the center of the fixed platform to the first common hinge; length ofL ₁ Is the length of the first connecting rod (1), L ₂ Is the length d of the second connecting rod (2) _s A thickness of the composite layered material;

s3, according to the angle theta of the required output of the driving motor (40) in the sub-driving mechanism connected with each branched chain _i A control command is issued to the corresponding driving motors (40), and then the driving motors (40) are driven to output corresponding angles theta _i The center point P of the movable platform reaches the target position.