CN106541418B - End effectors and industrial robots - Google Patents

Abstract

The invention discloses an end effector and an industrial robot. The end effector includes a pneumatic device, a base plate, a linkage and at least one linear motor. The linear motor and the pneumatic device are installed on the base plate. Driven by a linear motor. The industrial robot includes an end effector, a mechanical arm, a chuck, a cutting tool and a sensor. The cutting tool is mounted on the chuck, the chuck is fixedly connected to the linkage, the sensor is arranged on the cutting tool, and the bottom plate is fixed to the end of the mechanical arm. connect. The end effector of the invention effectively overcomes the disadvantages of poor dynamic response and low control precision of the pneumatic system, and improves the stability, accuracy and reliability of the entire continuous contact processing process.

Description

End effectors and industrial robots

technical field

The invention relates to the field of machining, in particular to an end effector and an industrial robot.

Background technique

In the process of precision machinery manufacturing, surface contact post-treatment such as polishing and grinding of the workpiece is the most basic process. Traditionally, such work is often done manually. However, as the cost of labor is getting higher and higher, this kind of jobs that do not require cultural skills occupy a high proportion of salary expenditures, and the machining industry is therefore stagnant. With the continuous development of industrial technology, people have put forward higher requirements for the surface grinding of mechanical workpieces, deburring of edges and corners, etc. Therefore, it is widely recognized that the use of mechanical arms to replace manual work has become a continuous contact surface post-processing work. One of the processing methods. This method can not only improve the quality of polishing and grinding, but also eliminate the need to use a lot of manual labor to carry out repeated operations, which further promotes the development of the processing industry.

At present, the mechanical arm used for grinding and polishing mainly adopts two methods to realize the force control in the processing process.

One is to install a force sensor on the manipulator, combine the force feedback signal with the parameter library stored inside the manipulator, and control the output force at the end of the manipulator by controlling the output torque of each joint of the robot. Although the mechanical arm can use this method to achieve force control in polishing and grinding operations, due to its limited internal setting parameters, the precision of polishing and grinding processes is far from meeting the process requirements. At the same time, when using this method for force control in continuous contact surface post-processing, due to the large inertia of the manipulator, the dynamic response is poor, making it difficult to improve the force control accuracy, so this direct force control method is only applicable for lightweight robotic arms.

Another force control method is to install a terminal force control device at the end of the mechanical arm. This force control method has low cost, does not depend on the robot itself, and is easy to achieve high control accuracy and good dynamic response, so it is widely used. . Existing terminal flexibility control mechanisms mostly use pneumatic artificial muscles or airbags to achieve active compliance force control with adjustable stiffness, but due to the slow response of the pneumatic system, there are serious nonlinearities, low control accuracy and long lag time in the control implementation. Therefore, it is not conducive to the rapid control of the production process, and it cannot meet the needs of precision machining.

Contents of the invention

The purpose of the present invention is to provide an end effector to solve the above-mentioned problems in the prior art.

In order to solve the above problems, according to one aspect of the present invention, an end effector is provided, and the end effector includes a pneumatic device, a base plate, a linkage and at least one linear motor, and the linear motor and the pneumatic device are installed On the bottom plate, the linkage is fixedly connected to the linear motor and the pneumatic device, so that the linkage can move driven by the pneumatic device and/or the linear motor.

Preferably, the end effector is a force-controlled end effector of a robot.

Preferably, the bottom plate is made of soft iron.

Preferably, the linkage is an extension rod, and the end effector further includes an end cover, wherein the extension rod passes through the end cover and is fixedly connected with the pneumatic device and the linear motor.

Preferably, the end effector includes a linear motor, and the linear motor is a voice coil motor, and the pneumatic device is arranged inside the voice coil motor.

Preferably, the voice coil motor includes an inner yoke and an outer yoke, the inner yoke and the outer yoke are fixedly connected to the bottom plate, and the pneumatic device is arranged inside the inner yoke .

Preferably, the voice coil motor further includes a guide ring, the guide ring is arranged between the inner yoke and the outer yoke and is fixedly connected to the bottom plate.

Preferably, the guide ring is made of polyoxymethylene.

Preferably, the voice coil motor further includes an inner magnet, an outer magnet, a coil holder and a coil, wherein the inner magnet is installed on the inner yoke, and the outer magnet is installed on the On the outer yoke, the coil is installed on the coil holder, and the coil holder is fixedly connected with the extension rod.

Preferably, the inner magnet is installed on the inner yoke by bonding, and the outer magnet is installed on the outer yoke by bonding.

Preferably, the coil holder is made of non-magnetic permeable material.

Preferably, the coil holder is made of aluminum alloy.

Preferably, the upper surface of the bottom plate is provided with a first groove and a second groove, the first groove is used for installing the pneumatic device, and the second groove is used for installing the linear motor .

Preferably, the end effector further includes an air source device, the pneumatic device is an air bag, the air bag is provided with an air inlet, and one end of the air bag provided with an air inlet is fixedly connected to the bottom plate, and the air bag The other end of is fixedly connected with the extension rod, and the air source device is in fluid communication with the air inlet.

Preferably, the inner diameter of the inner yoke is 104%-120% of the required installation diameter of the airbag.

Preferably, when the airbag is in the middle range, the length of the part of the extension rod above the end cover is at least half of the maximum compression amount of the airbag.

Preferably, the air source device includes an air source, a filter, a pressure reducing valve, an electromagnetic switch valve, a pressure gauge, and a pipeline, one end of the pipeline is connected to the gas source, and the other end of the pipeline is connected to the The air inlet of the air bag, the gas flowing out from the air source is filtered by the filter, flows into the pressure reducing valve, and then flows into the air bag, and the air bag is set between the pressure reducing valve and the air bag The electromagnetic switch valve and the pressure gauge.

Preferably, the end effector further includes a bearing, the end cover is provided with a through hole, the bearing is arranged in the through hole, and the extension rod penetrates into the bearing.

Preferably, the pneumatic device is an air cylinder, the air cylinder includes a piston, and the extension rod is fixedly connected with the piston.

Preferably, the linkage is a top plate, and the end effector includes 3 linear motors, and the 3 linear motors are evenly arranged around the pneumatic device.

Preferably, the linear motor is a voice coil motor.

Preferably, the pneumatic device is an air bag.

According to another aspect of the present invention, an industrial robot is also provided, the industrial robot includes the above-mentioned end effector, a mechanical arm, a chuck, a cutting tool and a sensor, wherein the cutting tool is mounted on the chuck, The chuck is fixedly connected with one end of the extension rod, the sensor is arranged on the cutting tool, and the bottom plate is fixedly connected with the end of the mechanical arm.

Preferably, the sensor is a one-dimensional force sensor.

Preferably, the cutting tools include knives and grinders.

The end effector of the present invention is a gas-electric hybrid robot force control end effector. While using the airbag to reduce the impact and vibration in the process of force control, it is combined with a voice coil motor to achieve rapid force compensation. The two work together and according to Actual processing needs to output different contact forces to realize active compliance force control in grinding, polishing and other processing processes.

Because the airbag has the advantages of compact structure, wear resistance, and low cost, the gas-electric hybrid robot end effector chooses to use the airbag to achieve impact resistance during processing. Since the airbag has only one air inlet and outlet, the airbag expands and expands to output a certain thrust after a given inflation pressure. Because the airbag has a certain compressibility, by changing the inflation pressure in the airbag and the compression amount of the airbag, the contact force applied by the airbag to the workpiece during the grinding and polishing process can be changed. It can reduce the mutual impact between the end effector of the gas-electric hybrid robot and the surface of the processed workpiece.

The invention effectively overcomes the disadvantages of poor dynamic response and low control precision of the pneumatic system, and improves the stability, accuracy and reliability of the entire continuous contact processing process.

The gas-electric hybrid robot end effector utilizes the impact resistance characteristics brought about by the compressibility of the gas, combined with the speed and accuracy of the motor control, it can realize the grinding and polishing process of the cutting tool (abrasive tool) ) and the rapid and precise control of the contact force between the workpiece and the stability of the entire machining process can be improved.

Compared with the prior art, the present invention has the following advantages:

(1) Pneumatic components adopt air bag type cylinder, which has simple structure, low price, no internal friction and long service life;

(2) On the basis of the airbag, a voice coil motor is added to improve the speed and accuracy of force control;

(3) The airbag is arranged in the center of the voice coil motor, so that the structure is compact and the stability is strong;

(4) The force control can be realized according to the need without depending on the robot, and the versatility is high.

Description of drawings

1 is a half-sectional view of an end effector according to an embodiment of the present invention, wherein the extension rod is extended to the farthest position;

2 is another half-sectional view of the end effector according to an embodiment of the present invention, wherein the extension rod is extended to a middle position;

Fig. 3 is a cross-sectional view of the end effector in Fig. 2 along the line A-A;

4 is another half-sectional view of the end effector according to an embodiment of the present invention, wherein the extension rod is in a retracted position;

Fig. 5 is a schematic diagram of the application of an end effector according to an embodiment of the present invention;

6 is a cross-sectional view of an end effector according to yet another embodiment of the present invention; and

Fig. 7 is a partial sectional view of an end effector according to another embodiment of the present invention.

Detailed ways

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to better understand the purpose, features and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but only to illustrate the essence of the technical solutions of the present invention.

The end effector of the present invention generally includes a pneumatic device, a base plate, a linkage and at least one linear motor, the linear motor and the pneumatic device are installed on the base plate, and the linkage is fixedly connected with the linear motor and the pneumatic device, so that the linkage Can be driven by pneumatic devices and/or linear motors.

Wherein the linkage is usually an extension rod or a top plate. When the linkage is an extension rod, the end effector usually also includes an end cover, and the end cover is provided with a through hole, and the extension rod passes through the through hole and is fixedly connected with the pneumatic device and the linear motor. And/or move up and down under the drive of linear motor.

Wherein, the pneumatic device may be an air bag, a cylinder, etc., and the linear motor is preferably a voice coil motor. The implementation mode in which the pneumatic device adopts the air bag and the linear motor adopts the voice coil motor will be described in detail below.

The end effector of an embodiment of the present invention will be described in detail below with reference to FIGS. 1-3 .

Fig. 1 is a half-sectional view of the end effector 100 of this embodiment, wherein the extension rod extends to the farthest position, and Fig. 2 is a half-section view of the end effector 100 of the present embodiment, wherein the extension rod extends Out to the middle position; Fig. 3 is a sectional view of the end effector in Fig. 2 along the line A-A; Fig. 4 is another half sectional view of the end effector of this embodiment, wherein the extension rod is in the withdrawn position.

As shown in FIGS. 1-4 , the end effector 100 includes an end cover 11 , a bottom plate 12 , an extension rod 13 , an air bag 14 , a bearing 15 and a voice coil motor 16 . The end cover 11 is provided with a through hole 121, the bearing 15 is installed in the through hole 121, the extension rod 13 passes through the through hole 121 and is fixedly connected with the air bag 14 and the voice coil motor 16, and the air bag 14 and the voice coil motor 16 are installed on the bottom plate 12. The extension rod 13 can move up and down driven by the air bag 14 and/or the voice coil motor 16 .

As shown in FIG. 1 , the voice coil motor 16 includes an inner magnet 161 , an outer magnet 162 , an inner yoke 163 , an outer yoke 164 , a coil 165 , a coil holder 166 and a guide ring 167 . The outer yoke 164 is arranged outside the inner yoke 163 , the inner magnet 161 is installed on the inner yoke 163 , the outer magnet 162 is installed on the outer yoke 164 , and the inner magnet 161 and the outer magnet 162 are arranged opposite to each other. The coil 165 is disposed on the coil holder 166 , and the coil 165 is located between the inner magnet 161 and the outer magnet 162 . The guide ring 167 is used to provide further guidance for the coil holder to move up and down during the working process of the end effector.

The airbag 14 is arranged in the middle of the bottom plate 12 , and the inner yoke 163 and outer yoke 164 of the voice coil motor 16 are arranged on the periphery of the airbag 14 and are fixedly connected to the bottom plate 12 , for example, by screws. The guide ring 167 is disposed between the inner yoke 163 and the outer yoke 164 , and is fixedly installed on the upper surface of the bottom plate 12 , for example, by screws.

Preferably, the inner magnet 161 and the outer magnet 162 of the voice coil motor 16 are respectively fixed to the inner yoke 163 and the outer yoke 164 by bonding. The end where the air inlet of the airbag 14 is located is fixedly installed on the upper surface of the bottom plate 12, for example, fixed by screws. The other end of the airbag 14 (the end where the air inlet is not located) is fixedly connected to the extension rod 13, and the coil holder 166 of the voice coil motor 16 is fixedly connected to the extension rod 13, so that the expansion and contraction of the airbag 14 and the up and down movement of the extension rod 13 Motion is linked. The bearing 15 installed between the extension rod 13 and the end cover 11 reduces the frictional force encountered when the extension rod 13 moves up and down.

Among them, in order to keep the coil 165 in a uniform magnetic field when moving up and down, the coil holder 166 of the voice coil motor 16 is made of a non-magnetic material, such as aluminum alloy, in order to further reduce the distance between the coil holder 166 and the coil holder 166. friction, the guide ring 167 is made of polyoxymethylene, in order to improve the installation accuracy of the inner yoke 163, the outer yoke 164, the guide ring 167 and the airbag 14, the base plate 12 is provided with a first groove and a second groove, The first groove is used for installing the airbag 14 , and the second groove is used for installing the voice coil motor 16 .

And in order to reduce the magnetic field leakage of the voice coil motor, the bottom plate 12 is made of soft iron.

FIG. 5 is a schematic diagram of the application of the end effector 100 of the present invention. The end effector 100 of the present invention is mainly used for an industrial robot 200 . As shown in Figure 5, industrial robot 200 comprises end effector 100 of the present invention, mechanical arm 201, chuck 30, cutting tool 40 and sensor (not shown), the bottom plate 12 of end effector 100 is connected on the mechanical arm 201 , the chuck 30 is connected to the extension rod 13 , and the cutting tool 40 is installed on the chuck 30 . The cutting tool 40 is provided with a sensor (not shown) connected to the controller (not shown), preferably, the sensor is a one-dimensional force sensor. Wherein, the sensor can be arranged between the cutting tool 40 and the chuck 30 .

As shown in FIGS. 1-4 , the air source device 20 includes an air source 25 , a filter 24 , a pressure reducing valve 23 , an electromagnetic switch valve 22 , a pressure gauge 21 , and a pipeline 27 . One end of the pipeline 27 is connected to the gas source 25, and the other end is connected to the air inlet of the air bag 14. The gas flowing out from the gas source flows into the pressure reducing valve 23 after being filtered by the filter 24, and then flows into the air bag 14. An electromagnetic switch valve 22 and a pressure gauge 21 are arranged between the air bag 14 .

During use, the airbag 14 is first inflated. The airbag 14 has a certain compression range. By adjusting the pressure reducing valve 23 to control the inflation pressure of the airbag 14 in the mid-compression range, the contact force between the cutting tool 40 installed on the end effector 100 and the workpiece 50 to be processed can be controlled. The sensor installed at the end of the cutting tool 40 detects the force signal and feeds it back to the controller. When the contact force reaches the set value, the controller sends a control signal to close the electromagnetic switch valve 22, so that the air bag 14 becomes a closed structure. Begin sanding or polishing.

When performing force control during grinding or polishing, etc., real-time dynamic force compensation is performed by the voice coil motor 16 . Specifically, when the surface of the workpiece 50 to be processed is uneven, the compression amount of the airbag 14 changes as the cutting tool 40 moves on the surface of the workpiece, so that the contact force of the airbag 14 on the surface of the workpiece 50 to be processed also changes. At this time, the sensor installed at the end of the cutting tool 40 detects the contact force and feeds it back to the controller; then, the controller compares the detected actual contact force with the set value to calculate the contact force to be compensated. Finally, the controller sends out a control signal and feeds the signal back to the driver of the voice coil motor. By changing the input current to the coil 165 of the voice coil motor, the output force of the voice coil motor 16 is changed, thereby compensating the contact force in real time. After the contact force is compensated, the force sensor detects the contact force again, compares and calculates it, and sends out a control signal. Such a closed-loop control method can always keep the contact force between the cutting tool 40 and the workpiece 50 controllable as required. , and finally finish the sanding or polishing work with high quality.

In the process of continuous contact processing such as grinding and polishing of complex curved surfaces, if the contact force between the cutting tool and the processed surface changes, the sensor can detect the changed contact force signal and feed it back to the controller. The loop control loop uses the principle of Ampere force to control the output force of the voice coil motor by adjusting the current input to the coil of the voice coil motor, so as to realize the compensation of the contact force. By directly inputting the control program into the controller, the offline operation of the entire force control process is realized.

An end effector according to another embodiment of the present invention will be described below with reference to FIG. 6 .

Fig. 6 is a cross-sectional view of the end effector of this embodiment. As shown in FIG. 6 , the main difference between this embodiment and the previous embodiment is that, in this embodiment, the pneumatic device is an air cylinder. For places that are not described in detail below, please refer to the relevant description of the previous embodiment.

As shown in Figure 6, in this embodiment, the pneumatic device is a cylinder, the cylinder includes a cylinder 14A, a piston 141 is arranged in the cylinder 14A, and the piston 141 is fixedly connected with the extension rod 13A, so that the up and down movement of the piston can A force is applied to the extension rod 13A, so that the extension rod 13A is linked with the piston 141 .

An end effector according to another embodiment of the present invention will be described below with reference to FIG. 7 . The parts that are not described in detail in this embodiment are the same as those in the foregoing two embodiments, and for details, refer to the descriptions of relevant parts of the foregoing two embodiments.

Fig. 7 is a partial sectional view of the end effector of this embodiment. As shown in FIG. 7 , the end effector 100B includes a top plate 11B, a bottom plate 12B, three voice coil motors 16 and an airbag 14, wherein the airbag 14 is fixedly installed in the middle of the bottom plate 12B, and the three voice coil motors 16 surround the airbag 14 Evenly arranged on the bottom plate 12B, the upper end of the airbag is fixedly connected on the top plate 11B, and the movers of the three voice coil motors 16 are also fixedly connected on the top plate 11B, so that the three voice coil motors 16 and the airbag 14 can be connected to the top plate 11B realizes linkage. During use, a chuck is installed on the top plate 11B, and a cutting tool is installed on the chuck.

In addition, a connecting rod can also be fixedly connected to the top plate 11B first, and then a chuck is connected to the connecting rod, and a cutting tool is installed on the chuck.

Although in this embodiment, a voice coil motor 16 is used, those skilled in the art can understand that other types of linear motors can also be used in this embodiment.

In addition, although in this embodiment, the solution adopted is to use 3 voice coil motors 16 to be evenly arranged around the airbag 14, those skilled in the art can understand that other numbers of voice coil motors can also be used to surround the airbag, for example 4 1, 5, 6, 7, etc., and also can adopt the mode that a plurality of motors are non-uniformly arranged around the airbag.

According to another aspect of the present invention, an industrial robot is also provided. The industrial robot 200 includes a mechanical arm 201, an end effector 100 of the present invention, a chuck 30, and a cutting tool 40. The bottom plate 12 of the end effector 100 is connected to the mechanical arm 201, and the chuck 30 is connected to the extension rod 13 for cutting. The cutter 40 is mounted on the chuck 30 . The cutting tool 40 is provided with a sensor (not shown) connected to the controller (not shown), preferably, the sensor is a one-dimensional force sensor.

Through the detailed description of the above embodiments, it can be seen that the main features of the present invention are that the control is realized by the cooperation of the pneumatic device and the linear motor, and the airbag is used to reduce the impact and vibration in the process of force control. The motor is used to realize fast force compensation, and the two work together to output different contact forces according to actual processing needs, and realize active compliant force control in grinding, polishing and other processing processes. The invention effectively overcomes the disadvantages of poor dynamic response and low control precision of the pneumatic system, and improves the stability, accuracy and reliability of the entire continuous contact processing process.

In the present invention, the fixed connection can be realized by conventional means in the field such as screws, bolts and bonding, and the cutting tools can include cutters and grinding tools.

Although in the present invention, the linkage is in the form of a protruding rod or a top plate, those skilled in the art can understand that the linkage can also be in other forms, as long as it can be linked with the pneumatic device and the linear motor, so that the The movement of the pneumatic device and the linear motor can be transmitted to the tool.

The preferred embodiments of the present invention have been described in detail above, but it should be understood that those skilled in the art can make various changes or modifications to the present invention after reading the above teaching content of the present invention. These equivalent forms also fall within the scope defined by the appended claims of this application.

Claims (9)

1. An end effector, characterized in that the end effector comprises a pneumatic device, a base plate, a linkage and at least one linear motor, the linear motor and the pneumatic device are mounted on the base plate, the The linkage is fixedly connected to the linear motor and the pneumatic device, so that the linkage can move under the drive of the pneumatic device and the linear motor; the linear motor is a voice coil motor; The linkage is an extension rod, and the end effector further includes an end cover, wherein the extension rod passes through the end cover and is fixedly connected with the pneumatic device and the linear motor; The end effector implements grinding or polishing through the pneumatic device, and the voice coil motor performs real-time dynamic force compensation when performing force control during the grinding or polishing process; The end effector also includes a bearing, the end cover is provided with a through hole, the bearing is arranged in the through hole, and the extension rod penetrates into the bearing. 2. The end effector according to claim 1, wherein the end effector comprises a linear motor, and the pneumatic device is arranged inside the voice coil motor. 3. The end effector according to claim 2, wherein the voice coil motor comprises an inner yoke and an outer yoke, and the inner yoke and the outer yoke are fixedly connected to the base plate, and The pneumatic device is arranged inside the inner yoke. 4. The end effector according to claim 3, wherein the voice coil motor further comprises a guide ring, the guide ring is arranged between the inner yoke and the outer yoke and is connected to the Bottom plate fixed connection. 5. The end effector according to claim 3, wherein the voice coil motor further comprises an inner magnetic steel, an outer magnetic steel, a coil holder and a coil, wherein the inner magnetic steel is mounted on the inner magnetic steel On the magnetic yoke, the outer magnetic steel is installed on the outer magnetic yoke, the coil is installed on the coil holder, and the coil holder is fixedly connected to the extension rod. 6. The end effector according to claim 2, characterized in that, the end effector also includes an air source device, the pneumatic device is an air bag, the air bag is provided with an air inlet, and the air bag is provided with an air inlet One end of the port is fixedly connected to the bottom plate, the other end of the airbag is fixedly connected to the extension rod, and the air source device is in fluid communication with the air inlet. 7. The end effector according to claim 2, wherein the pneumatic device is an air cylinder, the air cylinder includes a piston, and the extension rod is fixedly connected to the piston. 8 . The end effector according to claim 1 , wherein the linkage is a top plate, and the end effector includes 3 linear motors, and the 3 linear motors are evenly arranged around the pneumatic device. 9. An industrial robot, characterized in that, the industrial robot comprises the end effector according to any one of claims 1-8, and the industrial robot also comprises a mechanical arm, a chuck, a cutting tool and a sensor, wherein The cutting tool is installed on the chuck, the chuck is fixedly connected to the linkage, the sensor is arranged on the cutting tool, and the bottom plate is fixedly connected to the end of the mechanical arm.