CN113084850A

CN113084850A - Two-degree-of-freedom force-increasing type mechanical arm

Info

Publication number: CN113084850A
Application number: CN202110407154.2A
Authority: CN
Inventors: 王栋; 崔建伟; 姜汇策; 崔林威
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2021-04-15
Filing date: 2021-04-15
Publication date: 2021-07-09

Abstract

The invention provides a two-degree-of-freedom force-boosting type mechanical arm which comprises a shell, a motor support, a base, a servo motor, a bidirectional screw rod, a circular bearing, a vertical seat bearing, a side plate, a spring, a connecting rod, a magnetic encoder and the like. The servo motor is divided into a left servo motor and a right servo motor, the side plates comprise a left side plate and a right side plate, and the number of the springs is two, and the springs are respectively fixed at the upper part and the lower part of the circular bearings of the left side plate and the right side plate. The invention has the advantages that firstly, the spring device is added, so that the target object can be reliably fixed and clamped in the grabbing process; and secondly, the manipulator can be opened and closed and can also rotate, so that the degree of freedom of the manipulator is increased, and the manipulator is more favorable for realizing clamping operation. In addition, the clamping device has the advantages of simple structure, small volume, difficult deformation and strong practicability.

Description

Two-degree-of-freedom force-increasing type mechanical arm

Technical Field

The invention relates to the technical field of robots, in particular to a two-degree-of-freedom reinforcement type manipulator.

Background

With the continuous progress of science and technology, the development of robot technology is faster and faster, and more places begin to adopt robots to replace human beings to finish work. In ordinary production life, a robot is not convenient for grabbing plate materials, but grabbing of objects of the type is quite a lot in real life, such as grabbing a file box in a file repository, grabbing a book in a library or grabbing glass in a glass factory. For such plate objects, the existing mechanical arm is mostly designed to be a dexterous hand with an adsorption function, and the plate materials are grabbed by establishing a vacuum environment. However, the air pressure generated by the manipulator is not very high, so that the manipulator has general grabbing and lifting capacity, cannot grab objects with heavy weight, and is easy to leak air once the surfaces of the plate objects are not very flat, so that grabbing failure and falling-off are caused.

Therefore, there is a need for an improved conventional manipulator for grasping plate-like materials, which can reliably grasp heavy objects without falling off during movement. Typically, the motors on the robot are selected to be rated higher to increase torque, but in this case a greater input voltage or current is required. At the same time, a larger load may require a larger motor, resulting in an increase in the volume and weight of the robot arm, causing additional burden.

Disclosure of Invention

In order to solve the problems, the invention provides a two-degree-of-freedom reinforcement type manipulator and a control method, which are used for realizing reliable grabbing of plate objects.

The invention provides a two-degree-of-freedom boosting type manipulator which comprises a left side plate, a right side plate, a shell, a left servo motor, a right servo motor, a base, a vertical seat bearing, a bidirectional screw rod, a connecting rod, a coupler and a spring, wherein the vertical seat bearing is fixed on the base; right side servo motor passes through the shaft coupling to be fixed with the flange, the flange suit links to each other with positive and negative nut and two-way lead screw on circular bearing, controls the manipulator and opens and closed, left side board and right side board pass through circular bearing and install on two-way lead screw to fix on the base through the connecting rod, install positive and negative nut on the two-way lead screw and realize that corresponding curb plate opens and closed, the spring is total two, fixes respectively in the upper and lower two departments of the circular bearing of left side board and right side board, follows left side board and right side board and stretch or compress.

As a further improvement of the invention, the left servo motor comprises a magnetic encoder for controlling the rotation of the manipulator, and the right servo motor comprises a magnetic encoder for controlling the opening and closing of the manipulator.

Compared with the existing analysis method, the method has the characteristics and beneficial effects that:

firstly, the manipulator is additionally provided with the spring device in the process of grabbing an object, so that the grabbing force is increased, and the target object can be reliably fixed and clamped. And for the motors with the same rated power, the manipulator can clamp objects with larger weight. And secondly, the manipulator can be opened and closed and can also rotate, so that the degree of freedom of the manipulator is increased, and the manipulator is more favorable for realizing clamping operation. In addition, the clamping device has the advantages of simple structure, small volume, difficult deformation and strong practicability.

Drawings

FIG. 1 is a front external view of the present invention;

FIG. 2 is a right side elevational view of the present invention;

FIG. 3 is a schematic diagram of the force applied during clamping of the present invention;

description of the figure numbering:

111. a left side plate; 112. a right side plate; 12. a housing; 131. a left servo motor; 132. a right servo motor; 14. a base; 15. a vertical seat bearing; 16. a bidirectional screw rod; 17. a connecting rod; 18. a coupling; 19. a spring; 21. a motor bracket; 22. a circular bearing; 23. a positive and negative nut; 24. a flange; 25. a magnetic encoder.

Detailed Description

The invention is described in further detail below with reference to the following detailed description and accompanying drawings:

the invention provides a two-degree-of-freedom boosting type mechanical arm and a control method, and reliable grabbing of plate objects is realized.

Fig. 1 is a front external view of the present invention, which includes a left side plate 111, a right side plate 112, a housing 12, a left servo motor 131, a right servo motor 132, a base 14, a vertical seat bearing 15, a bidirectional screw 16, a connecting rod 17, a coupling 18, and a spring 19.

Fig. 2 is a right external view of the present invention, which includes a motor bracket 21, a circular bearing 22, a positive and negative nut 23, a flange 24, and a magnetic encoder 25.

The working principle is as follows: the left and

right servo motors

131 and 132 are fixed to the motor bracket 21 and the housing 12, and the motor bracket 21 is also fixed to the housing 12. The left side plate 111 and the right side plate 112 are mounted on the bidirectional screw rod 16 through the bearing 22 and fixed on the base 14 through the connecting rod 17. The right servo motor 132 is provided with a magnetic encoder 25, and is connected with the bidirectional screw rod 16 through a coupler 18, a flange 24, a bearing 22 and a positive and negative nut 23 to control the left side plate 111 and the right side plate 112 to realize opening and closing operations. The left servo motor 131 is equipped with a magnetic encoder 25, and is fixed with the vertical seat bearing 15 through a coupler 18 to drive the base 14 and control the rotation of the left side plate 111 and the right side plate 112. The spring device 19 is installed between the left side plate 111 and the right side plate 112, and the spring 19 is still in a stretching state in the gap left by the left side plate 111 and the right side plate 112 in the minimum closing state, so when the left side plate 111 and the right side plate 112 clamp an object, not only the inward pressing force generated by the motor 132 but also the inward elastic force from the spring 19 are generated on the left side plate 111 and the right side plate 112. In addition, the front ends of the left side plate 111 and the right side plate 112 are designed to be wedge-shaped, which is beneficial to completing the clamping operation deep into the gap.

The relative motion of the screw pair in the bidirectional screw rod under the action of moment and axial load can be seen as that the horizontal force acting on the middle diameter pushes the sliding block (object) to move along the screw thread.

The torque acting on the screw pair is related to the axial load driving force as follows:

in the formula 1, T is the moment on the screw pair, namely the moment provided by the bidirectional screw rod; f_aFor axial load drivesThe power is the extrusion force provided by the motor on the screw rod when clamping an object; d₂The diameter of a cylinder on the threaded screw rod is called the pitch diameter, and the widths of a tooth-shaped groove and a protrusion on a bus of the cylinder are equal; psi is the lead angle, at the pitch diameter d₂On the cylinder, the tangent line of the spiral line forms an included angle with a plane vertical to the axis of the thread; ρ is the rubbing angle.

The torque normally provided by the screw is known, so that the driving force F can be derived from equation 1_aThe derivation formula is as follows:

therefore, the larger the weight of the foreign object, the larger the driving force required by the foreign object, the larger the corresponding torque and the larger the motor power.

The stress situation and the working steps of the invention when clamping an object are described with reference to fig. 3:

1. the device of the invention is mounted on other devices, such as industrial robots, mechanical arms, through the housing 12, and is driven by the other devices to approach the target object. And when the object reaches the working position, scanning the information on the target through the scanning device, and confirming the object to be clamped. The left side plate 111 and the right side plate 112 are opened and go deep between the objects to start to clamp the objects. In the clamping process, the manipulator can rotate by the left motor 131, the grabbing posture is adjusted, the adjustment is not needed by an external mechanical arm, the joint freedom degree is increased equivalently, and the design mode is more flexible and is simple to operate. The left and

right side plates

111 and 112 are inserted into the inclined object space, and then the robot arm is rotated to perform the aligning process.

2. The stress condition of the left side plate 111 and the right side plate 112 during the process of clamping the object is shown in fig. 3. Taking the right side plate 112 as an example, the torque from the right servo motor 132 is first applied to the lead screw to provide an inward motor pressing force F_a. Since the spring 19 is always in tension during the movementIn the stretching state, the direction of the elastic force generated by the elastic force is consistent with the direction of the force provided by the motor, and the magnitude is F_SK × x, where k is the elastic coefficient and x is the deformation amount. Because the manipulator of the invention is provided with two spring devices, the total pressure provided when the right side plate is closed is F_a+2×F_S. In the same way, the extrusion force provided by the left side plate is the same as that of the right side plate, and the direction is inward and points to the back splint object.

Therefore, on the premise of the same rated power and rated torque, the two-degree-of-freedom force-increasing type manipulator device designed by the invention can provide larger extrusion force due to the existence of the spring 19, so that an object with larger weight can be clamped, the clamping effect is safer and more reliable, and the two-degree-of-freedom force-increasing type manipulator device is not easy to fall off in the movement process. On the other hand, it is also shown that, in the case that the weight of the object to be gripped is known, the gripping force required can be estimated, and the motor torque required by the invention is smaller under the tensile force of the spring, and the motor power is correspondingly smaller, so that the volume is smaller and the price is lower. In addition, due to the existence of the spring 19, a certain fixing effect is achieved on the left side plate 111 and the right side plate 112, and the manipulator can keep a synchronous state in the rotating process without deformation and other problems.

The above description is only one of the preferred embodiments of the present invention, and is not intended to limit the present invention in any way, but any modifications or equivalent variations made in accordance with the technical spirit of the present invention are within the scope of the present invention as claimed.

Claims

1. Two degree of freedom reinforcement formula manipulators contains left side board (111), right side board (112), shell (12), left servo motor (131), right servo motor (132), base (14), vertical seat bearing (15), two-way lead screw (16), connecting rod (17), shaft coupling (18) and spring (19), its characterized in that: the vertical seat bearing (15) is fixed on the base (14), the left servo motor (131) and the right servo motor (132) are fixed with the shell (12) through the motor support (21), the motor support (21) is fixed on the shell (12), the shell (12) is fixed on the robot, and the left servo motor (131) is fixed with the vertical seat bearing (15) through the coupler (18) and drives the vertical seat bearing (15) to rotate so as to realize rotation of the manipulator; right side servo motor (132) are fixed with flange (24) through shaft coupling (18), flange (24) suit is on circular bearing (22) and positive and negative nut (23) and two-way lead screw (16) link to each other, and the control manipulator opens and closes, left side board (111) and right side board (112) are installed on two-way lead screw (16) through circular bearing (22) to fix on base (14) through connecting rod (17), install positive and negative nut (23) on two-way lead screw (16) and realize that corresponding curb plate opens and the closure, spring (19) are total two, fix respectively in the upper and lower two places of circular bearing (22) of left side board (111) and right side board (112), follow left side board (111) and right side board (112) and stretch or compression.

2. The two-degree-of-freedom force-increasing manipulator of claim 1, wherein: left servo motor (131) contain control manipulator rotatory magnetic encoder (25), right servo motor (132) contain control manipulator open and closed magnetic encoder (25).