CN108818017B

CN108818017B - Thin-walled workpiece mirror image milling top bracing device guided by vision

Info

Publication number: CN108818017B
Application number: CN201810748473.8A
Authority: CN
Inventors: 和延立; 张圣光; 朱胜伟
Original assignee: Northwestern Polytechnical University
Current assignee: Northwestern Polytechnical University
Priority date: 2018-07-10
Filing date: 2018-07-10
Publication date: 2021-01-05
Anticipated expiration: 2038-07-10
Also published as: CN108818017A

Abstract

The invention discloses a vision-guided mirror image milling jacking device for a thin-walled workpiece, which consists of a jacking device vision part and a mechanical arm movement part; and the visual part of the jacking device adopts two binocular vision cameras to look at any pose of the processing head in real time. The binocular vision camera is placed on one side of the machining head of the mirror milling machine tool. Before processing, a characteristic picture of the processing head is shot and stored in the computer. When a workpiece is machined, the pose of the workpiece is shot in real time by the binocular camera, and each image is matched with the image stored in the computer in advance by applying a feature matching technology based on a GMS algorithm. And determining the pose conversion relation between the camera coordinate system and the mechanical arm coordinate system. When the tail end of the machining head moves, the tail end executor of the mechanical arm moves in real time in a mirror image synchronization mode along with the machining head. The servo motors of all joints of the mechanical arm are controlled by a computer to realize waist rotation, shoulder rotation, elbow rotation and wrist rotation, and the movement of the tail end jacking part is realized.

Description

Thin-walled workpiece mirror image milling top bracing device guided by vision

Technical Field

The invention relates to the technical field of aerospace manufacturing, in particular to a vision-guided mirror-image milling and jacking device for a thin-walled workpiece.

Background

Aerospace vehicles have many large-sized thin-walled parts, such as aircraft skins, which are extremely easily deformed during the manufacturing process and become difficult to machine. The traditional processing technology is chemical milling, and the processing technology has the disadvantages of complex flow, low precision, large environmental pollution and great threat to the health of operators. In recent years, some large-scale manufacturers abroad develop numerical control machine tools to replace chemical milling, so that the numerical control machine tools are free from pollution to the environment and human bodies and become a new green manufacturing result. The most prominent result of numerical control machining of thin-walled parts is mirror milling. The mirror image mirror device is composed of two five-coordinate horizontal machine tools which move synchronously, a main shaft of one machine tool is a processing head, a main shaft of the other machine tool is a jacking head, the jacking head and the processing head are respectively positioned at two sides of a thin-wall part in the processing process, and the jacking head and the processing head move synchronously on the workpiece along the same normal line.

The invention patent CN104440158A discloses an airplane skin mirror image milling jacking method and equipment, which is characterized in that the equipment comprises a front push head, a back jacking and a lubricating device. But it cannot follow up according to the position and attitude of the tool.

Disclosure of Invention

In order to avoid the defects in the prior art and overcome the defect of poor follow-up performance of a mirror image milling machining equipment top bracing technology, the invention provides a visual-guiding thin-wall part mirror image milling top bracing device.

The invention solves the technical problem by adopting the technical scheme that the device comprises a jacking device vision part and a mechanical arm movement jacking part, wherein the vision part adopts two binocular vision cameras which are arranged on one side of a machining head of a mirror milling machine tool; storing the characteristic picture shot by the processing head into a computer; the motion control card controls the rotation angle and the rotation speed of the motor so as to control the motion of the mechanical arm, the mechanical arm motion top bracing part comprises a waist rotating mechanism, a shoulder rotating mechanism, an elbow rotating mechanism, a wrist rotating mechanism and a tail end top bracing mechanism, it is characterized in that the waist rotating mechanism comprises a mechanical arm base, a waist servo motor, a rotating shaft leather pad, a waist small belt wheel, a waist driving belt, a waist large belt wheel and a waist turntable, the quadrilateral of the mechanical arm base is fixed on the ground through bolts, the waist servo motor is arranged below the mechanical arm base, the small waist belt wheel is arranged on a rotating shaft of the waist servo motor, the large waist belt wheel is fixed on the waist turntable, the small belt wheel is a driving wheel, the belt drives the large belt wheel and the waist turntable to rotate, and the rotating shaft leather pad is fixed on the mechanical arm base through bolts, so that the effects of reducing the waist turntable and the mechanical arm base are achieved;

the shoulder rotating mechanism comprises a shoulder servo motor, shoulder small belt wheels, shoulder belts and a shoulder rotating shaft, the shoulder servo motor is composed of two components with the same structure, the shoulder servo motor is positioned in a motor groove of the waist turntable, the two shoulder small belt wheels with the same structure are respectively fixed on an output shaft of the shoulder servo motor, the shoulder rotating shaft is installed on the waist rotating shaft through screws and bolts, the shoulder rotating shaft is provided with wheel grooves of the two belt wheels, and the two belts are respectively sleeved on the wheel groove of the shoulder rotating shaft and the wheel groove of the shoulder small belt wheel; one side of the waist rotating shaft is connected with the connecting pipe through a bolt and a nut;

the elbow rotating mechanism comprises an elbow base, an elbow servo motor, an elbow small belt wheel, an elbow transmission belt, an elbow rotating shaft gasket, an elbow connecting wheel, an elbow axial servo motor, an elbow axial rotating shaft, an elbow axial bearing and an elbow wrist connecting piece, wherein the elbow base is connected with a waist and elbow connecting pipe by bolts and nuts, the elbow servo motor is arranged on a motor groove of the elbow servo motor, the elbow small belt wheel is arranged on a rotating shaft of the elbow servo motor, the elbow connecting wheel is arranged on a shaft of the elbow base by the bolts and nuts, an elbow rotating shaft is arranged between the elbow connecting wheel and a shaft of the elbow base, an elbow axial bearing is installed on the elbow axial rotating shaft, an elbow axial servo motor is installed on a motor groove of an axial motor of the elbow connecting wheel, and an elbow wrist connecting piece is respectively connected with the elbow wrist connecting pipe and the elbow axial rotating shaft through bolts and nuts;

wrist slewing mechanism includes wrist base, wrist servo motor, wrist band pulley, wrist belt, wrist fifth wheel, wrist rotation packing ring, and the wrist base is installed on elbow and elbow wrist connecting pipe, and wrist servo motor installs on the motor groove of wrist base, and the wrist band pulley is installed in wrist servo motor's axis of rotation, and the wrist fifth wheel passes through bolt and nut and installs on the wrist base.

The tail end jacking mechanism comprises a jacking head ball, a jacking head and a jacking head spring, the jacking head is positioned on the wrist connecting wheel and is connected by threads, and the jacking head ball and the spring are respectively installed in the jacking head.

Advantageous effects

The invention provides a vision-guided mirror image milling top bracing device for a thin-walled workpiece. The device comprises a top bracing device vision part and a mechanical arm movement top bracing part, wherein the vision part adopts two binocular vision cameras which are arranged on one side of a processing head of a mirror milling machine tool; storing the characteristic picture shot by the processing head into a computer; the motion control card controls the rotation angle and the rotation speed of the motor so as to control the motion of the mechanical arm, and the mechanical arm motion top support part comprises a waist rotating mechanism, a shoulder rotating mechanism, an elbow rotating mechanism, a wrist rotating mechanism and a tail end top support mechanism.

Firstly, determining a pose conversion relation between a camera coordinate system and a mechanical arm coordinate system, and determining a pose relation between end effectors of the mechanical arm according to the pose of a processing head and by considering the thickness compensation of a tool workpiece. Therefore, when the end of the processing head moves, the end effector of the mechanical arm moves in real time in mirror image synchronization with the processing head.

The mechanical arm top support device is fixed on the ground, and the rotation angle and the rotation speed of the servo motor are controlled by the motion control card so as to control each motor of the mechanical arm to move the mechanical arm. The mechanical arm base is fixed on the ground through four bolts, so that the stability of the top bracing device is enhanced. A rotating belt is arranged between the mechanical arm base and the waist turntable, so that the waist can rotate flexibly, and friction is reduced. Waist servo motor passes through the rotation that the transmission mode of band pulley drove the waist carousel, and the band pulley transmission not only can realize slowing down, more can play overload protection's effect, prevents that certain joint of arm from leading to the damage of motor because of the load is too big. The two shoulder servo motors also drive the waist rotating shaft to rotate in a belt wheel transmission mode, and the two servo motors can provide enough power for the waist rotating shaft and realize the acceleration and overload protection effects. The elbow is provided with an axial rotating servo motor, and the aim of increasing the freedom degree is to improve the flexibility of the mechanical arm end effector. Similarly, the transmission mode that the wrist servo motor drives the wrist to be connected also adopts the transmission of a belt wheel. The jacking device of the end effector adopts flexible steel balls and springs to match with the jacking, and plays a role in preventing processed parts from being scratched in the jacking process.

Drawings

The invention relates to a visual guide thin-wall part mirror image milling top bracing device, which is further described in detail with reference to the accompanying drawings and embodiments.

FIG. 1 is a schematic view of a machining head, a binocular camera and a jacking device working together to machine a thin-walled part.

Fig. 2 is a schematic structural diagram of an intelligent shoring device for mirror-image milling of thin-wall parts.

Fig. 3 is a schematic view of the belt wheel transmission of the waist rotating base.

FIG. 4a is a front view of the lumbar carousel; figure 4b is a cross-sectional view of the lumbar carousel.

FIG. 5 is a front view of the shoulder spindle.

Fig. 6 is a schematic view of the shoulder rotating small belt pulley driving the waist rotating shaft under the action of the belt pulley.

FIG. 7a is a front view of the elbow attachment wheel; figure 7b is a top view of the elbow attachment wheel.

Figure 8 is a schematic illustration of an elbow fifth wheel drive.

FIG. 9a is a schematic illustration of the assembly between the elbow attachment wheel, elbow steering bearing, elbow wrist attachment, and elbow axial bearing; fig. 9b is a cross-sectional view taken along line a-a of fig. 9 a.

FIG. 10a is a front view of the elbow base; figure 10b is a cross-sectional view of the elbow base.

Figure 11 is a cross-sectional view of the wrist base.

Figure 12 is a schematic view of a wrist-rotating pulley drive.

FIG. 13a is a wrist coupling wheel; figure 13b is a cross-sectional view of the wrist coupling wheel.

FIG. 14 is a schematic view of a head support structure.

In the drawings

1. The mechanical arm comprises a mechanical arm base 2, a waist servo motor 3, a rotating shaft leather pad 4, a waist small belt wheel 5, a waist transmission belt 6, a waist large belt wheel 7, a waist rotary table 8, a shoulder servo motor 9, a shoulder small belt wheel 10, a shoulder belt 11, a shoulder rotating shaft 12, a shoulder rotating shaft washer 13, a first connecting pipe 14, an elbow base 15, an elbow servo motor 16, an elbow small belt wheel 17, an elbow transmission belt 18, an elbow rotating shaft washer 19, an elbow connecting wheel 20, an elbow axial motor 21, an elbow axial rotating shaft 22, an elbow axial bearing 23, an elbow wrist connecting piece 24, a wrist connecting pipe 25, a wrist base 26, a wrist servo motor 27, a wrist small belt wheel 28, a wrist belt 29, a wrist connecting wheel 30, a wrist rotating washer 31, a jacking head ball 32, a jacking head 33 and a jacking head spring.

Detailed Description

The embodiment is a vision-guided mirror image top bracing milling device for thin-walled workpieces.

Firstly, two binocular vision cameras are arranged on one side of a processing head, so that the binocular vision cameras can see any pose of the processing head in real time. The vision part adopts two binocular vision cameras 35 which are arranged on one side of a mirror image milling machine tool processing head 36. Before processing, a characteristic picture of the processing head is shot and stored in the computer. When the processing head is processing the workpiece 34, the binocular camera can shoot the pose in real time, each image and the image stored in the computer before are subjected to feature matching by applying a feature matching technology based on GMS algorithm, and the pose of the processing head relative to the camera is calculated in real time by using an RPNP technology after matching is finished. And determining a pose conversion relation between a camera coordinate system and a mechanical arm coordinate system, and determining a pose relation between the mechanical arm end effector according to the pose of the processing head and by considering the thickness compensation of the tool workpiece. Therefore, when the end of the processing head moves, the end effector of the mechanical arm moves in real time in mirror image synchronization with the processing head. In the device for moving the mechanical arm, the mechanical arm has 5 degrees of freedom, and 6 servo motors are driven, and each servo motor independently controls the motion of the servo motor under the action of a motion control card. Therefore, the top supporting device at the tail end moves flexibly.

Referring to fig. 1 to 14, the visually guided mirror image milling jacking device for thin-walled workpieces of the present embodiment is composed of a jacking device visual part and a mechanical arm movement jacking part; the vision part adopts two binocular vision cameras which are arranged on one side of the processing head of the mirror milling machine tool; storing the characteristic picture shot by the processing head into a computer; the motion control card controls the rotation angle and the rotation speed of the motor, so as to control the motion of the mechanical arm, the mechanical arm motion top support part comprises a waist rotating mechanism, a shoulder rotating mechanism, an elbow rotating mechanism and a wrist rotating mechanism, wherein the waist rotates to be the first degree of freedom of the mechanical arm, and the waist rotating mechanism comprises a mechanical arm base 1, a waist servo motor 2, a rotating shaft leather pad 3, a waist small belt wheel 4, a waist driving belt 5, a waist large belt wheel 6 and a waist rotary table 7. Arm base 1 is the quadrangle, fix subaerial with 4 screws, waist servo motor 2 installs the below at the arm base with bolt and nut, waist belt lace wheel 4 is installed in waist servo motor's axis of rotation, waist belt lace wheel 6 is fixed on the waist carousel, belt lace wheel is the action wheel, drive belt lace wheel and waist carousel 7 rotation under the drive of belt, axis of rotation leather packing 3 is bolted fixation on the arm base with the bolt, play the effect that reduces waist carousel and arm base. When the computer transmits a driving signal to the waist servo motor, the waist servo motor 2 is installed to drive the waist small belt wheel 4 to rotate after receiving the signal transmitted by the computer, and the waist driving belt 5 drives the waist large belt wheel 6 fixed on the waist turntable to rotate, so that the waist is rotated.

Shoulder rotation is the second degree of freedom of the mechanical arm; the shoulder rotating mechanism consists of two identical shoulder servo motors 8, two identical shoulder small belt wheels 9, a shoulder belt 10 and a shoulder rotating shaft 11. Two same shoulder servo motors 8 are installed in a motor groove of the waist turntable, 2 same shoulder small belt wheels 9 are installed on a rotating shaft of the shoulder servo motors 8 respectively, a shoulder rotating shaft is installed on the waist rotating shaft through screws and bolts, wheel grooves of 2 belt wheels are formed in the shoulder rotating shaft, and 2 belts are sleeved on the wheel grooves of the shoulder rotating shaft and the wheel grooves of the shoulder small belt wheels respectively. When the computer transmits a driving signal to the shoulder servo motors, 2 identical shoulder servo motors 8 respectively drive the shoulder small belt wheels 9 after receiving the signal transmitted by the computer, and the shoulder small belt wheels 9 drive the shoulder rotating shafts 11 to rotate through the shoulder belts 10, so that the shoulder is rotated.

The elbow rotates with two degrees of freedom; the elbow rotating mechanism comprises an elbow base 14, an elbow servo motor 15, an elbow small belt wheel 16, an elbow transmission belt 17, an elbow rotating shaft gasket 18, an elbow connecting wheel 19, an elbow axial servo motor 20, an elbow axial rotating shaft 21, an elbow axial bearing 22 and an elbow wrist connecting piece 23. The elbow base 14 is connected with the waist and elbow connecting pipes through bolts and nuts, the elbow servo motor 15 is installed on a motor groove of the elbow servo motor, the elbow small belt wheel 16 is installed on a rotating shaft of the elbow servo motor, the elbow connecting wheel 19 is installed on a shaft of the elbow base through the bolts and nuts, and an elbow rotating shaft is placed between the elbow connecting wheel and the shaft of the elbow base. When the computer transmits a driving signal to the waist servo motor, the elbow servo motor 15 receives the signal transmitted by the computer and then drives the elbow small belt wheel to rotate, and the small belt wheel drives the elbow connecting wheel 19 to rotate by driving the elbow driving belt 17. This rotation is the first rotation of the elbow. The elbow axial rotating shaft 21 is a tie for connecting the servo motor and the wrist connecting piece, firstly, the elbow axial shaft 22 is installed on the elbow axial rotating shaft in a bearing mode, and the elbow axial servo motor is installed on a motor groove of the elbow connecting wheel axial motor. The elbow wrist connecting piece 23 is respectively connected with the elbow, the wrist connecting pipe and the elbow axial rotating shaft by bolts and nuts. When the computer transmits a driving signal to the waist servo motor, the elbow axial servo motor 20 drives the elbow axial rotating shaft 21 to rotate after receiving the signal transmitted by the computer, meanwhile, the elbow axial rotating shaft 21 is a tie for connecting the servo motor and the wrist connecting piece, firstly, the elbow axial bearing 22 is installed on the elbow axial rotating shaft, and the elbow axial servo motor is installed on a motor slot of the axial motor of the elbow connecting wheel. The rotation of the elbow axial rotating shaft 21 drives the rotation of the elbow wrist connecting piece 23 and the elbow wrist connecting pipe 24, so as to realize the elbow axial rotation. This rotation is the second rotation of the elbow.

The wrist rotation is the fifth degree of freedom of the mechanical arm; the wrist rotation mechanism includes a wrist base 25, a wrist servo motor 26, a wrist small belt wheel 27, a wrist belt 28, a wrist connecting wheel 29, and a wrist rotation washer 30. The wrist base 25 is installed on the elbow and wrist connecting pipe 24, the wrist servo motor 26 is installed on the motor groove of the wrist base, the wrist small belt wheel 27 is installed on the rotating shaft of the wrist servo motor, and the wrist connecting wheel is installed on the wrist base through a bolt and a nut. When the computer transmits a driving signal to the wrist servo motor, the wrist servo motor receives the signal transmitted by the computer and then drives the wrist small belt wheel to rotate, and the wrist small belt wheel drives the wrist connecting wheel to rotate under the transmission of the wrist belt, so that the rotation of the wrist is realized.

The tail end jacking mechanism comprises a jacking head ball 31, a jacking head 32 and a jacking head spring 33. The top supporting head is arranged on the wrist linking wheel and is connected by threads, and the ball of the top supporting head and the spring are respectively arranged in the top supporting head. The servo motors of all joints of the mechanical arm are controlled by a computer to realize waist rotation, shoulder rotation, elbow rotation and wrist rotation, and finally the movement of the tail end jacking part is realized.

Claims

1. A vision-guided shoring device for mirror-image milling of thin-walled workpieces comprises a shoring device vision part and a mechanical arm movement shoring part, wherein the vision part adopts two binocular vision cameras which are arranged on one side of a machining head of a mirror-image milling machine tool; storing the characteristic picture shot by the processing head into a computer; the motion control card controls the rotation angle and the rotation speed of the motor so as to control the motion of the mechanical arm, the mechanical arm motion top bracing part comprises a waist rotating mechanism, a shoulder rotating mechanism, an elbow rotating mechanism, a wrist rotating mechanism and a tail end top bracing mechanism, the method is characterized in that: the waist rotating mechanism comprises a mechanical arm base, a waist servo motor, a rotating shaft leather pad, a waist small belt wheel, a waist driving belt, a waist large belt wheel and a waist turntable, the quadrilateral of the mechanical arm base is fixed on the ground through bolts, the waist servo motor is arranged below the mechanical arm base, the small waist belt wheel is arranged on a rotating shaft of the waist servo motor, the large waist belt wheel is fixed on the waist turntable, the small belt wheel is a driving wheel, the belt drives the large belt wheel and the waist turntable to rotate, and the rotating shaft leather pad is fixed on the mechanical arm base through bolts, so that the effects of reducing the waist turntable and the mechanical arm base are achieved;

2. The vision-guided mirror-image milling top bracing device for thin-walled parts according to claim 1, wherein the terminal top bracing mechanism comprises a top bracing head ball, a top bracing head and a top bracing head spring, the top bracing head is positioned on the wrist connecting wheel and is in threaded connection, and the top bracing head ball and the spring are respectively installed in the top bracing head.