CN106863356A - A kind of constant force exports actuator - Google Patents

Abstract

The invention discloses a constant force output actuator, which comprises at least four automatic adjustment cylinders, a column body, a top cover and a bottom cover and a controller, and the output pressure of each automatic adjustment cylinder is automatically adjusted to realize constant output pressure of the actuator. The automatic adjustment cylinder includes an air supply pipeline, two solenoid valves and three cylinders, the first cylinder is arranged above the second cylinder, and two pistons are arranged in the first cylinder, wherein the upper piston is provided with a push rod connected thereto , the lower piston is fixedly connected with the piston in the second cylinder through a rigid connecting rod, the top of the third cylinder is connected with the lower part of the first cylinder through a pipeline, and the part between the first cylinder, the second cylinder and the third cylinder is filled with hydraulic oil. An air port is provided on the top and bottom of a cylinder, and the four air ports are respectively connected to the air supply pipeline through two electromagnetic valves. The invention can be used in conjunction with the robot to keep the grinding wheel and the irregular workpiece in constant contact.

Description

A constant force output actuator

technical field

The invention relates to the technical field of robot end effectors, in particular to a constant force output actuator.

Background technique

In the field of machinery industry processing, automation technology is more and more widely used, and robots are the key to automatic production, so they have been applied in more and more fields. With the development of robots in a deeper and wider direction and their intelligence With the continuous improvement of automation, the application range of robots will also become larger and larger, extending from the automotive industry to other manufacturing fields. People's requirements for robots will also be higher and higher. Robots need to have higher sensitivity and flexibility in order to engage in more precise automation work and ensure the quality of processing. Therefore, there is a need for an actuator that can be used in conjunction with a robot, can automatically compensate for the impact of gravity, and maintain a constant force output, so that more demanding work can be automated.

Contents of the invention

The purpose of this invention is to design a device that can freely expand and contract and keep in contact with the workpiece, can automatically compensate the influence of the gravity of the top cover itself, measure and feed back the value of the actual output force in real time, and save all the data within 20 seconds before the current point in time. , an actuator that always maintains a constant force output.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A constant force output actuator, comprising a cylindrical column and at least four automatic adjustment cylinders, the column includes a top cover, a bottom cover and a column body, the bottom cover is fixedly connected with the column body, the top The cover is a movable cover; the cylinder body of each automatic adjustment cylinder is fixedly connected with the bottom cover, and the freely telescopic push rod on the top of each automatic adjustment cylinder is fixedly connected with the top cover. One of the automatic adjustment cylinders is located at At the center of the bottom cover, other automatic adjustment cylinders are symmetrically distributed around the center of the bottom cover; the automatic adjustment cylinders include an air supply pipeline, a first solenoid valve, a second solenoid valve, a first cylinder, a second cylinder, and a third cylinder Cylinder, the first cylinder is located above the second cylinder, the first cylinder is provided with two pistons, wherein the upper piston is provided with a push rod that can extend out of the top of the first cylinder, the lower piston and the piston in the second cylinder pass through The rigid connecting rod is fixedly connected, the top of the third cylinder is connected with the lower side of the first cylinder through a communication pipe, the part between the two pistons of the first cylinder and the part above the piston of the third cylinder are filled with hydraulic oil, the top of the first cylinder and The bottom of the third cylinder is respectively provided with gas port 1 and gas port 4, and the top and bottom of the second cylinder are respectively provided with gas port 2 and gas port 3. The gas port 1 and gas port 4 are connected with the gas supply pipeline through the first solenoid valve, The control gas port 1 and gas port 4 are respectively connected to the gas supply pipeline or to exhaust the atmosphere. The gas port 2 and gas port 3 are connected to the gas supply pipeline or to exhaust the atmosphere through the second solenoid valve. Air supply line or exhaust atmosphere.

As an improvement, the bottom cover is provided with a controller and a gravity sensor, and the gravity sensor connects the measured inclination angle data of the bottom cover to the controller, and the controller controls the first electromagnetic valve and the first solenoid valve of each automatic adjustment cylinder. The opening size and valve position of the second solenoid valve.

As an improvement, a pressure sensor for detecting hydraulic oil pressure is provided on the side of the first cylinder to compensate the influence of the gravity of the top cover on the output pressure of each automatic adjustment cylinder.

As an improvement, the air supply pipeline is provided with an air filter device for filtering and decompressing the compressed air.

The working principle of the constant force output actuator described in the present invention is as follows: the automatic adjustment cylinder is used to generate the required constant output force. Since the gas is compressible and the output force range of the cylinder is not large, the automatic adjustment of the hydraulic cylinder is controlled by the cylinder. Adjust the cylinder to generate a constant output force, install a pressure sensor on the side of each hydraulic cylinder that automatically adjusts the cylinder, detect the pressure value of the hydraulic cylinder in real time, and feed back to the controller, and store the data within 20 seconds in the controller In the database, at the same time through the controller I/O port to output different control signals to adjust the opening and closing of different channels of the first solenoid valve and the second solenoid valve in real time to change the flow direction of the compressed gas, thereby ensuring constant force output. Due to the influence of the gravity of the constant force output actuator, the pressure output by the push rod of each automatic adjustment cylinder will deviate from the set pressure value. A gravity sensor is installed inside the constant force output actuator to detect different pose states through the gravity sensor The deviation angle is lower, and the controller calculates the additional output pressure due to the need to compensate the influence of the gravity of the top cover itself, and the controller I/O port outputs different control signals to adjust the opening and closing of different channels of the solenoid valve in real time. Change the output pressure of the cylinder to achieve the purpose of constant force output of the actuator.

As a description of the constant force control part of the present invention, in order to ensure that the actuator can communicate with almost all brands of robot control systems on the market, the controller should have Ethernet TCP/IP, Profibus, CANopen, Analog I/O, XML, DeviceNet, ProfiNet, Modbus TCP and dual combo communication protocols.

As an explanation of the constant force control part of the present invention, the database can record all data within 20 seconds before any point in time, so as to analyze the pressure output change of the actuator within 20 seconds.

As a description of the constant force executive part of the present invention, there are four cylinders installed in the cylinder of the constant force output actuator, one cylinder is installed in the center of the cylinder bottom cover, and the other three cylinders are installed around it. 120 degree angle evenly distributed. The hydraulic cylinders are respectively fixedly installed on the side of each automatic adjustment cylinder, used in conjunction with the automatic adjustment cylinder, and the hydraulic oil is driven by the cylinder to generate stable pressure.

The beneficial effects of the present invention are:

Through the use of the constant force output actuator of the present invention in conjunction with the robot, the constant force output actuator can effectively ensure that it is always in contact with the workpiece, can automatically compensate the influence of gravity, measure and feed back the actual force value, and save the existing one All the data within 20 seconds before the time point always maintain the required constant force output.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the constant force output actuator.

Figure 2 is a schematic diagram of the automatic adjustment of the elongation of the cylinder push rod.

Fig. 3 is a schematic diagram of automatically adjusting cylinder push rod boosting.

Fig. 4 is a schematic diagram of automatically adjusting the shortening of the cylinder push rod.

Fig. 5 is a block diagram of the control system of the present invention.

Figure 6 is a schematic diagram of gravity sensor compensation calculation.

Explanation of symbols in the figure:

1-column; 2-controller; 3-gravity sensor, 41-cylinder A, 42-cylinder O, 43-cylinder B, 44-cylinder C, 51-hydraulic cylinder A, 52-hydraulic cylinder O, 53-hydraulic Cylinder B, 54-hydraulic cylinder C, 61-pressure sensor A, 62-pressure sensor O, 63-pressure sensor B, 64-pressure sensor C, 7-power supply and communication interface, 8-compressed air interface, 91-cylinder A 92-the focus of cylinder O, 93-the focus of cylinder B, 94-the focus of cylinder C, 10-air source, 11-the first solenoid valve, 12-the second solenoid valve, 13-the first One cylinder, 14-second cylinder, 15-third cylinder, 16-push rod, 17-air port one, 18-air port two, 19-air port three, 20-air port four, 21-rigid connecting rod, 22-air filter Device, 23-top cover, 24-bottom cover, 25-pressure sensor.

detailed description

The present invention will be illustrated below in conjunction with the accompanying drawings.

As shown in Figure 2, a kind of automatic adjustment cylinder of constant force output actuator comprises air source 10, air supply pipeline, first solenoid valve 11, second solenoid valve 12, first cylinder 13, second cylinder 14, and The third cylinder 15, the first cylinder 13 is located above the second cylinder 14, the first cylinder 13 is provided with two pistons, wherein the upper piston is provided with a push rod 16 that can stretch out the top of the first cylinder 13, and the lower piston It is fixedly connected with the piston in the second cylinder 14 through a rigid connecting rod 21, the top of the third cylinder 15 is connected with the lower side of the first cylinder 13 through a communication pipe, the part between the two pistons of the first cylinder 13 and the third cylinder 15 The parts above the piston are filled with hydraulic oil, the top of the first cylinder 13 and the bottom of the third cylinder 15 are respectively provided with air port one 17 and air port four 20, and the top and bottom of the second cylinder 14 are respectively provided with air port two 18 and air port three 19, so Said air port one 17 and air port four 20 are connected to the output pipe of the first electromagnetic valve 11 through the air supply pipeline, and the input end of the first electromagnetic valve 11 is connected to the gas source 10 or the exhaust air through the air intake pipeline, and the first electromagnetic valve 11 is controlled to connect with the air port respectively. The air supply pipeline connected to the first 17 and the air port four 20 is connected to the air intake pipe or exhausted to the atmosphere. The second air port 18 and the third air port 19 are connected to the output pipeline of the second electromagnetic valve 12 through the air supply pipeline, and the input end of the second electromagnetic valve 12 The air intake pipe is connected to the air source 10 or the air is exhausted, and the second electromagnetic valve 12 controls the air supply pipes connected to the air port two 18 and the air port three 19 respectively to be connected to the air intake pipe or to exhaust the air.

The side of the first cylinder 13 is provided with a pressure sensor 25 for detecting the pressure of the hydraulic oil. In order to detect whether the pressure of the hydraulic oil pressure meets the set value through the controller 2, if not, the controller 2 controls the first solenoid valve 11 and the second solenoid valve 12 to control.

The air supply pipeline is provided with an air filter device 22 for filtering and decompressing the compressed air.

The automatic adjustment cylinder controls the output force of the push rod 16 according to the pressure sensor 25 detecting the hydraulic oil pressure. When the pressure sensor 25 detects that the hydraulic oil pressure is lower than the set value, the first solenoid valve 11 controls the gas port. The intake air volume of four 20 is used to increase the hydraulic oil pressure; when the push rod 16 of the automatic adjustment cylinder needs to be extended, the air intake volume of the air port four 20 is increased through the control of the first electromagnetic valve 11, and the discharge of the air port one 17 is increased at the same time air, so that the piston of the third cylinder 15 rises, and the piston of the first cylinder 13 rises through the transmission of hydraulic oil, thereby driving the push rod 16 to elongate. When the push rod 16 needs to be further elongated, it is controlled by the second solenoid valve 12 Air port 3 19 intakes air, and air port 2 18 exhausts, so that the piston of the second cylinder 14 rises, and the piston at the bottom of the first cylinder 13 is driven to further rise through the rigid connecting rod 21, so that the push rod 16 continues to extend; otherwise, when it is necessary to push When the rod 16 is shortened, the second solenoid valve 12 first controls the air intake at the second air port 18, and the air port three 19 exhausts, driving the lower piston of the first cylinder 13 to descend, and the push rod 16 connected with the upper piston of the first air cylinder 13 then descends. , if the push rod 16 needs to be further shortened, the first solenoid valve 11 controls the air intake through the air port one 17, and the air port four 20 exhausts, so the push rod 16 can be further shortened.

A constant force output actuator using the above-mentioned automatic adjustment cylinder, comprising a cylindrical column and four automatic adjustment cylinders, the column includes a top cover 23, a bottom cover 24 and a column body 1, the bottom cover 24 It is fixedly connected with the column body 1, and the top cover 23 is a movable cover; the cylinder bodies of the four automatic adjustment cylinders are all fixedly connected with the bottom cover 24, and the freely telescopic push rods 16 on the top of the four automatic adjustment cylinders are all connected with the top The cover 23 is loosely connected and fixedly connected, and the four automatic adjustment cylinders are respectively cylinder A41, cylinder B43, cylinder C44 and cylinder O42, wherein cylinder O42 is set at the center of the bottom cover 24, and cylinder A41, cylinder B43 and cylinder C44 are centered on cylinder O42 Symmetrically distributed, the bottom cover 24 is provided with a controller 2 and a gravity sensor 3, the inclination angle data of the bottom cover 24 measured by the gravity sensor 3 is connected to the controller 2, and the controller 2 controls each automatic adjustment cylinder The opening degree and valve position of the first electromagnetic valve 11 and the second electromagnetic valve 12, the angle measured by the gravity sensor 3 is the angle between the normal line of the bottom cover 24 and the horizontal plane, and each automatic adjustment is obtained through a series of calculations. Because the cylinder is affected by gravity, it is necessary to actually set the compensation value of the hydraulic oil pressure. The compensation value is used to correct the hydraulic oil pressure setting value of each automatic adjustment cylinder, so that each automatic adjustment cylinder actually acts on the top cover. The pressure equalization on the 23 is the same.

The column body 11 is also provided with a power supply and communication interface 7 and a compressed air interface 8 . The controller 2 communicates with an external robot through a power supply and a communication interface 7 .

The constant force output actuator of the present invention is mainly used on the robot arm, the bottom cover 24 of the constant force output actuator is fixedly connected with the robot arm, and the grinding wheel for workpiece grinding is installed on the top cover 23 of the constant force output actuator. If the shape of the grinding wheel is irregular, then in the grinding process, in order to maintain a balanced contact force between the grinding wheel and the workpiece, it is necessary to be able to automatically adjust the direction and contact pressure of the grinding wheel, and the purpose of the present invention is to provide an implementation that can automatically adjust the pressure angle. The device keeps the grinding wheel in constant contact with the irregular workpiece during the grinding process.

When the grinding wheel and the workpiece are in a parallel state, the bottom cover 24, the top cover 23 and the grinding wheel of the constant force output actuator are all in a parallel state, then each automatic adjustment cylinder output force of the constant force output actuator is the same, when the grinding wheel and the workpiece When not parallel, there is an angle between the grinding wheel and the workpiece, and the top cover 23 fixedly connected to the grinding wheel also tilts at a certain angle. In addition to the automatic adjustment cylinder located in the center of the constant force output actuator, some automatic adjustment cylinders are due to the top cover 23 and The distance between the bottom cover 24 becomes smaller and the compression causes the pressure on the push rod 16 to increase, and another part of the automatic adjustment cylinder will reduce the pressure on the push rod 16 due to the increase in the distance between the top cover 23 and the bottom cover 24. Now top cover 23 is subjected to the unbalanced pressure of each automatic adjustment cylinder push rod 16, so that the contact pressure between grinding wheel and workpiece is unbalanced, so it is necessary to adjust each automatic adjustment cylinder output pressure to make it reach the same. The following takes an automatic adjustment cylinder of the constant force output actuator as an example to illustrate its action principle.

First, the stroke of the push rod 16 of the automatic adjustment cylinder is extended. In order to ensure that the grinding wheel carried by the top cover 23 of the constant force output actuator is always in contact with the workpiece with a constant pressure, when the constant force output actuator performs the process tasks along the curved surface of the workpiece, it needs When the push rod 16 stroke of the automatic adjustment cylinder is extended, due to the elongation of the push rod 16 stroke of the automatic adjustment cylinder, the volume in the first cylinder 13 increases and the pressure decreases. When the output pressure set by the constant force output actuator is small, that is, P ₀ <P _min , where P ₀ is the hydraulic oil pressure of the automatic adjustment cylinder corresponding to the output pressure set by the constant force output actuator, P _min The minimum pressure for driving the rigid connecting rod 21 of the second cylinder 14 to work. The hydraulic oil pressure P in the automatic adjustment cylinder is detected by the pressure sensor 25. When P _< P0, the controller 2 controls the first electromagnetic valve 11 to act, so that the air port four 20 inputs compressed air and the air port one 17 discharges air, so that Piston promotes push rod 16 to rise.

Second, the stroke of the push rod 16 of the automatic adjustment cylinder is shortened. In order to ensure that the grinding wheel carried by the top cover 23 of the constant force output actuator is always in contact with the workpiece with a constant pressure, when the constant force output actuator performs the process tasks along the curved surface workpiece, it needs to be used When the push rod 16 stroke of the automatic adjustment cylinder was shortened, due to the shortening of the push rod 16 stroke of the automatic adjustment cylinder, the volume in the first cylinder 13 decreased and the pressure increased. The hydraulic oil pressure P in the automatic adjustment cylinder is detected by the pressure sensor 25. When P>P ₀ , the controller 2 controls the first electromagnetic valve 11 and the second electromagnetic valve 12 respectively, so that the air port one 17 and the air port of the air cylinder are automatically adjusted. Two 18 input compressed air, air port three 19 and air port four 20 discharge compressed air, so that push rod 16 and rigid connecting rod 21 are descended.

Third, the stroke of the push rod 16 of the automatic adjustment cylinder remains unchanged and needs to be boosted. When the push rod 16 of the automatic adjustment cylinder needs to be boosted, and the output pressure set by the constant force output actuator is relatively high, that is, P ₀ >P _min , through the detection of the pressure sensor 25, the hydraulic oil pressure P in the cylinder is automatically adjusted. When P<P ₀ , the controller 2 controls the second solenoid valve 12, so that the compressed air is input into the third port 19 and the air is discharged from the second port 18, so that the rigidity The connecting rod 21 rises to increase the pressure of the hydraulic oil in the automatic adjustment cylinder, so that the automatic adjustment cylinder push rod 16 outputs a larger pressure; when the cylinder piston push rod 16 needs to be boosted, but the output pressure set by the constant force output actuator When it is small, that is, P ₀ <P _min , the pressure P of the hydraulic oil in the cylinder is automatically adjusted through the detection of the pressure sensor 25. When P < P ₀ , the controller 2 controls the first solenoid valve 11, so that the air port 4 20 of the cylinder inputs compression Air increases the hydraulic oil pressure in the automatic adjustment cylinder, so that the push rod 16 of the automatic adjustment cylinder outputs a larger pressure.

Fourth, the stroke of the push rod 16 of the automatic adjustment cylinder remains unchanged and needs to be decompressed. When the push rod 16 of the automatic adjustment cylinder needs to be decompressed, the hydraulic oil pressure P in the automatic adjustment cylinder is detected by the pressure sensor 25. When P>P At ₀ , the controller 2 respectively controls the first solenoid valve 11 and the second solenoid valve 12 to reduce the exhaust volume of air port 17 and air port 2 18, and at the same time reduce the air intake volume of air port 3 19 and air port 4 20, thereby reducing the execution The output pressure of the piston push rod 16.

In Fig. 1, 51, 52, 53 and 54 respectively represent the hydraulic cylinders of cylinder A41, cylinder O42, cylinder B43 and cylinder C44, the hydraulic cylinder refers to the hydraulic oil part on each cylinder, 61, 62, 63 and 64 respectively refer to pressure sensors for measuring hydraulic oil pressure on the four cylinders.

As an explanation of the constant force control part of the cylinder of the present invention, the gravity compensation scheme of the constant force output actuator based on the gravity sensor 3 is specifically implemented as follows: take the installation center point of the constant force output actuator cylinder O42 as the center of the circle, and establish the spatial coordinates The system is O-xyz, the plane xoy is the horizontal plane, and α is the angle value between the normal line of the bottom cover 24 of the constant force output actuator and the horizontal plane. The following figure is a schematic diagram of the constant force output actuator under the action of gravity G, and the four automatic adjustment cylinders in the constant force output actuator balance the effect of gravity on the axial direction of the automatic adjustment cylinder. The static analysis of the automatic adjustment of the axial direction of the cylinder shows that:

ΔF _A +ΔF _B +ΔF _C +ΔF _O ＝G·sinα (1)

Among them, ΔF _A , ΔF _B , ΔF _C and ΔF _O are the pressure values output by cylinder A41, cylinder B43, cylinder C44 and cylinder O42 to compensate gravity G respectively. The output of the 4 inner cylinders to compensate gravity should be equal, that is

ΔF _A ＝ ΔF _B ＝ ΔF _C ＝ ΔF _O (2)

Combining formula (1) and formula (2), it can be seen that the output pressure of the cylinder in the actuator to compensate for the influence of gravity on the axial direction of the actuator is

ΔF＝ΔF _A ＝ΔF _B ＝ΔF _C ＝ΔF _O ＝1/4Gsinα

By installing the gravity sensor 3 inside the actuator to detect the included angle α between the actuator and the horizontal plane xoy, the controller 2 solves the force of the cylinder in the actuator to compensate gravity along the axial direction of the cylinder (that is, the normal direction of the bottom cover 24). The required output pressure ΔF, when the output pressure of the actuator is set to F, the actual output pressure of each cylinder in the actuator should be ΔF+F, and the pressure P in the hydraulic cylinder is detected by the corresponding pressure sensor 25, when At this time, the difference between the actual pressure value in the hydraulic cylinder and the set pressure value is calculated by the controller 2 to control the opening and closing of different channels of the first solenoid valve 11 and the second solenoid valve 12 of the cylinder, so as to realize the pressure in the actuator. The output pressure of the hydraulic cylinder reaches the purpose of the required pressure value.

Claims (4)

1. A constant force output actuator, characterized in that: comprise a cylindrical column and at least four automatic adjustment cylinders, the column includes a top cover, a bottom cover and a column body, and the bottom cover and the column body The top cover is fixedly connected, and the top cover is a movable cover; the cylinder body of each automatic adjustment cylinder is fixedly connected with the bottom cover, and the freely telescopic push rod on the top of each automatic adjustment cylinder is fixedly connected with the top cover. One automatic adjustment cylinder is arranged at the center of the bottom cover, and other automatic adjustment cylinders are symmetrically distributed around the center of the bottom cover; the automatic adjustment cylinder includes an air supply pipeline, a first solenoid valve, a second solenoid valve, a first cylinder, a second Two cylinders, and a third cylinder, the first cylinder is located above the second cylinder, the first cylinder is provided with two pistons, wherein the upper piston is provided with a push rod that can stretch out from the top of the first cylinder, and the lower piston is connected to the second cylinder. The pistons in the second cylinder are fixedly connected by rigid connecting rods, the top of the third cylinder is connected with the lower side of the first cylinder through a communication pipe, the part between the two pistons of the first cylinder and the part above the piston of the third cylinder are filled with hydraulic oil , the top of the first cylinder and the bottom of the third cylinder are respectively provided with gas port 1 and gas port 4, and the top and bottom of the second cylinder are respectively provided with gas port 2 and gas port 3, and the gas port 1 and gas port 4 pass through the first electromagnetic valve and the gas supply pipeline The first solenoid valve controls gas port 1 and gas port 4 to be connected to the gas supply pipeline or exhaust the atmosphere respectively, the gas port 2 and gas port 3 are connected to the gas supply pipeline or exhaust the atmosphere through the second solenoid valve, and the second solenoid valve controls gas port 2 Connect to the gas supply pipeline or exhaust the atmosphere respectively with gas port 3. 2. A constant force output actuator as claimed in claim 1, characterized in that: the bottom cover is provided with a controller and a gravity sensor, and the inclination angle data of the bottom cover measured by the gravity sensor is connected to the controller, The controller controls the opening size and valve position of the first electromagnetic valve and the second electromagnetic valve of each automatic adjustment cylinder, and compensates the influence of the gravity of the top cover on the output pressure of each automatic adjustment cylinder. 3. A constant force output actuator as claimed in claim 1, wherein a pressure sensor for detecting the pressure of hydraulic oil is provided on the side of the first cylinder. 4. A constant force output actuator as claimed in claim 2, characterized in that: said air supply pipeline is provided with an air filter device for filtering and depressurizing compressed air.