A single-degree-of-freedom active adaptive force control flange for industrial robots

Abstract

The present invention discloses a single-degree-of-freedom active adaptive force control flange for industrial robots, which mainly includes a fixed platform, a moving platform, a linear motor, an air spring, and a guide device, etc.; and has an inner cylindrical bracket and an outer cylindrical bracket coaxially nested and installed, and the guide device is arranged between the outer side wall of the inner cylindrical bracket and the inner side wall of the outer cylindrical bracket; one end of the outer cylindrical bracket has an opening for accommodating the inner cylindrical bracket, and the other end is fixedly connected to the fixed platform; the inner cylindrical bracket is located at the inner end of the outer cylindrical bracket, and an air spring is arranged between the inner cylindrical bracket and the fixed platform, and the outer end of the inner cylindrical bracket is fixedly connected to the moving platform; the motor stator of the linear motor is installed at the opening of the outer cylindrical bracket; the motor mover is installed on the inner side of the moving platform, and is arranged coaxially with the inner cylindrical bracket. The present invention has high force control accuracy, good dynamic response performance and a large force control range, and is suitable for industries such as parts assembly and polishing.

Description

Technical Field

[0001] The invention relates to an industrial robot terminal device, and in particular to an industrial robot terminal force control device used for operations such as parts assembly, polishing and grinding. Background Art

[0002] In the parts assembly, polishing and grinding industries, the traditional operation method is manual operation, which requires a large amount of human resources and is costly. The quality of the operation often depends on the experience and proficiency of the workers, and the quality cannot be guaranteed to be completely consistent. At the same time, the manual operation method has low production efficiency and the working environment poses a great threat to the safety and health of workers. The various disadvantages of traditional manual operation have forced the operation method in this technical field to change to a new direction of high efficiency and high quality.

[0003] With the advancement of science and technology, industrial robots have gradually gained favor from major companies for their advantages such as good flexibility, large working space, simple control, low cost and high efficiency. The working methods of industrial robots in production operations can be mainly divided into contact operations and non-contact operations. In contact operations, the control methods of industrial robots can be divided into position control and force control. Position control relies on adjusting the various joints of the industrial robot to achieve the posture change of the end, while force control relies on adjusting the torque of each joint of the industrial robot to achieve the output force of the end, also known as direct force control. This method requires the establishment of an accurate robot dynamics model and the output torque of each joint of the industrial robot is inversely solved according to the output force of the end, which is more troublesome to implement. The indirect force control of the industrial robot is to install a force control device at the end of the robot. The industrial robot is responsible for position control, and the force control device is responsible for the output force control of the end. The combination of the two realizes the force / position decoupling of the industrial robot.

[0004] Most existing force control devices are driven by pneumatic or electric motors. Pneumatic drive has serious nonlinearity in control, low force control accuracy, and gas has the disadvantage of response hysteresis, which cannot achieve rapid adjustment of contact force. The motor drive method has poor flexibility and is prone to vibration during operation. In addition, the force control device driven by a single motor has a large mass and does not meet the lightweight design requirements. In order to meet the needs of industries such as parts assembly and polishing, it is urgent to develop a force control device with high precision, fast response, good flexibility, light mass, and a large force control range. Summary of the invention

[0005] The purpose of the present invention is to provide a single-degree-of-freedom active adaptive force control flange to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a single-degree-of-freedom active adaptive force control flange for an industrial robot, mainly comprising a fixed platform, a moving platform, a linear motor, an air spring and a guide device; and having an inner cylindrical bracket and an outer cylindrical bracket coaxially nested and installed, the guide device is arranged between the outer side wall of the inner cylindrical bracket and the inner side wall of the outer cylindrical bracket; one end of the outer cylindrical bracket has an opening for accommodating the inner cylindrical bracket, and the other end is fixedly connected to the fixed platform; the inner cylindrical bracket is located at the inner end portion of the outer cylindrical bracket, and an air spring is arranged between the inner cylindrical bracket and the fixed platform; the outer end portion of the inner cylindrical bracket is fixedly connected to the moving platform; the motor stator of the linear motor is installed in the opening portion of the outer cylindrical bracket; the motor mover is installed on the inner side of the moving platform and is arranged coaxially with the inner cylindrical bracket.

[0007] As a further improvement of the above technical solution, the single-degree-of-freedom active adaptive force control flange is provided with a displacement sensor for detecting the displacement of the dynamic platform, and a pressure sensor for detecting the actual contact force of the end-effector tool; the displacement sensor and the pressure sensor feed back the actual measurement values ​​to the controller, and the controller adjusts the current in the linear motor to adjust the force deviation between the actual contact force and the expected force.

[0008] As a further improvement of the above technical solution, the open side of the outer cylindrical bracket has three mounting brackets spaced 120° apart, and the slider in the guide device is connected to the mounting bracket; the inner cylindrical bracket located inside the outer cylindrical bracket has three pin brackets spaced 120° apart, and the guide rail in the guide device is connected to the pin bracket.

[0009] As a further improvement of the above technical solution, the guide devices are evenly distributed along the circumference at intervals of 120°, and each guide rail adopts a double slider structure.

[0010] As a further improvement of the above technical solution, the inner cylindrical bracket has a hollow structure between the pin brackets; the outer cylindrical bracket has a hollow structure between the mounting brackets.

[0011] As a further improvement of the above technical solution, the air spring and the linear motor are installed coaxially, respectively located at the two ends of the inner cylindrical bracket, which is beneficial to the heat dissipation of the linear motor and avoids the influence of temperature on the gas performance in the air spring.

[0012] As a further improvement of the above technical solution, the motor stator has a circular groove, and inner and outer radiating permanent magnet rings are provided on the inner and outer walls of the circular groove; the motor mover is embedded in the circular ring formed between the inner and outer radiating permanent magnet rings, and the motor mover forms a bilateral air gap with the inner and outer permanent magnet rings and interacts with the permanent magnet rings.

[0013] As a further improvement of the above technical solution, a mechanical spring is provided between the moving platform and the outer cylindrical support.

[0014] As a further improvement of the above technical solution, there are multiple mechanical springs, which are evenly distributed along the circumference of the moving platform and the outer cylindrical support.

[0015] As a further improvement of the above technical solution, the displacement sensor is a high-precision grating sensor, including a patch bracket, a grating piece, a grating reader and a grating reader mounting frame; the grating reader is fixedly connected to the outer cylindrical bracket through the grating reader mounting frame; the grating piece is attached to the patch bracket, and the patch bracket is fixed on the moving platform and moves with the moving platform.

[0016] Compared with the existing force control device, the single-degree-of-freedom active adaptive force control flange of the present invention has the following advantages:

[0017] 1. The air spring and the linear motor in the single-degree-of-freedom active adaptive force control flange are coaxially and staggered in space through the nested inner cylindrical bracket and the outer cylindrical bracket, which is beneficial to the heat dissipation of the motor and effectively avoids the influence of the heat of the linear motor on the gas performance in the air spring;

[0018] 2. A mechanical spring is added to the single-degree-of-freedom active adaptive force control flange, which effectively makes up for the shortcoming of the slow response speed of the air spring as a high-damping element and improves the dynamic response of the system;

[0019] 3. The linear motor adopts an internal and external radiation permanent magnet ring structure, which not only makes the air gap magnetic field strength more uniform, but also helps to improve the air gap magnetic density, so that the motor has a greater thrust density and faster response time;

[0020] 4. The single-degree-of-freedom active adaptive force control flange uses a linear motor and an air spring in parallel as the driving element. The two complement each other and have a "macro + micro" force control method with high force control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a structural diagram of the single-degree-of-freedom active adaptive force control flange in this embodiment.

[0022] Figure 2 is a top view of the single-degree-of-freedom active adaptive force control flange in this embodiment.

[0023] Figure 3 2 is a structural diagram of the inner cylindrical support and the outer cylindrical support in this embodiment.

[0024] Figure 4 is a cross-sectional view of the linear motor in this embodiment.

[0025] Figure 5 It is a radiation magnetization diagram of the permanent magnet in this embodiment.

[0026] Figures 1 to 5The figures in the figure are as follows: moving platform 1, displacement sensor 2, patch bracket 21, grating sheet 22, grating reader 23, grating reader mounting bracket 24, mechanical spring 3, linear motor 4, motor stator 41, permanent magnet ring 42, motor mover 43, guide device 5, block 51, guide rail 52, slider 53, outer cylindrical bracket 6, inner cylindrical bracket 7, air spring 8, fixed platform 9, air pipe joint 10, connecting flange 11. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the embodiments and drawings. It should be pointed out that the following embodiments are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0028] The single-degree-of-freedom active adaptive force control flange for an industrial robot of the present invention mainly comprises a fixed platform 9, a moving platform 1, a linear motor 4, an air spring 8 and a guide device 5, and has an inner cylindrical bracket 7 and an outer cylindrical bracket 6 which are coaxially nested and installed. The guide device 5 is arranged between the outer side wall of the inner cylindrical bracket 7 and the inner side wall of the outer cylindrical bracket 6. One end of the outer cylindrical bracket 6 has an opening for accommodating the inner cylindrical bracket 7, and the other end is fixedly connected to the fixed platform 9.

[0029] The inner cylindrical support 7 is located at the inner end of the outer cylindrical support 6, and an air spring 8 is provided between the inner cylindrical support 7 and the fixed platform 9. The outer end of the inner cylindrical support 7 is fixedly connected to the moving platform 1. The motor stator 41 of the linear motor 4 is installed at the opening of the outer cylindrical support 6. The motor mover 43 is installed on the inner side of the moving platform 1 and is arranged coaxially with the inner cylindrical support 7.

[0030] One end of the air spring 8 is connected to the fixed platform 9 , and the other end is connected to the inner cylindrical support 7 . The air spring 8 acts on the moving platform 1 through the inner cylindrical support 7 , and forms a parallel drive with the linear motor 4 .

[0031] The single-degree-of-freedom active adaptive force control flange is provided with a displacement sensor 2 for detecting the displacement of the moving platform 1, and a pressure sensor for detecting the actual contact force of the end-actuator. The displacement sensor 2 and the pressure sensor feed back the actual measured value to the controller, and the controller adjusts the current in the linear motor 4 to adjust the force deviation between the actual contact force and the expected force.

[0032] The open side of the outer cylindrical bracket 6 has three mounting brackets spaced 120 degrees apart, and the slider 53 in the guide device 5 is connected to the mounting bracket. The inner cylindrical bracket 7 located inside the outer cylindrical bracket 6 has three pin brackets spaced 120 degrees apart, and the guide rail 52 in the guide device 5 is connected to the pin bracket.

[0033] In this embodiment, the inner cylindrical bracket 7 is cylindrical in shape and hollow inside, and is used to place the linear motor 4. There are three pin brackets at a 120° interval on the top, which are used to place the guide rail 52 in the guide device 5. The outer cylindrical bracket 6 is also cylindrical in shape, and the lower half is hollow, and is used to place the air spring 8. The upper half protrudes three mounting brackets at a 120° interval, and is used to install the slider 53 in the guide device 5. The inner cylindrical bracket 7 and the outer cylindrical bracket 6 are not only required to be coaxially nested, but also the three slider 53 mounting brackets of the outer cylindrical bracket 6 and the three pin brackets of the inner cylindrical bracket 7 must be aligned.

[0034] The inner cylindrical bracket 7 has a hollow structure between the pin brackets. The outer cylindrical bracket 6 has a hollow structure between the mounting brackets. The integral hollow structure adopted by the inner cylindrical bracket 7 and the outer cylindrical bracket 6 not only contributes to the lightweight design of the force control flange, but also makes the device compact and stable, and is also conducive to reducing the installation error of the parts.

[0035] The air spring 8 and the linear motor 4 are coaxially mounted and are located at both ends of the inner cylindrical bracket 7. The space-staggered structure of the air spring 8 and the linear motor 4 is beneficial to the heat dissipation of the linear motor 4 and prevents the temperature from affecting the gas performance in the air spring 8.

[0036] The linear motor 4 includes a motor stator 41, a permanent magnet ring 42 and a motor mover 43. The motor stator 41 is mounted on the outer cylindrical bracket 6, and the motor mover 43 is connected to the moving platform 1. The outer cylindrical bracket 6 and the moving platform 1 are both provided with grooves for positioning the motor stator 41 and the motor mover 43 to ensure that the two are installed coaxially. The motor stator 41 has an annular groove, and inner and outer radiating permanent magnet rings 42 are provided on the inner and outer walls of the annular groove; the motor mover 43 is embedded in the annular ring formed between the inner and outer radiating permanent magnet rings 42, and the motor mover 43 forms a bilateral air gap with the inner and outer permanent magnet rings 42, and interacts with the permanent magnet rings 42. The use of the inner and outer radiating permanent magnet rings 42 not only increases the number of air gap edges, but also helps to improve the air gap magnetic density, so that the motor has a greater thrust density and a faster response time.

[0037] A mechanical spring 3 is provided between the moving platform 1 and the outer cylindrical support 6. There are a plurality of mechanical springs 3, which are evenly distributed along the circumference of the moving platform 1 and the outer cylindrical support 6.

[0038] In this embodiment, three mechanical springs 3 are evenly distributed along the circumference between the moving platform 1 and the outer cylindrical support 6. In this system, the air spring 8 is a high damping element with a slow response speed. Adding the mechanical spring 3 helps to increase the system stiffness and improve the dynamic response characteristics of the system.

[0039] The guide devices 5 are evenly spaced at intervals of 120° along the circumference, and each guide rail 52 adopts a double slider 53 structure. In this embodiment, the guide device 5 includes a stopper 51, a guide rail 52 and a slider 53. The guide rail 52 is mounted on the inner cylindrical bracket 7, and the slider 53 is mounted on the outer cylindrical bracket 6. The stopper 51 is used to limit the displacement of the slider 53 to prevent the slider 53 from derailing. The three guide devices 5 are evenly spaced at intervals of 120° along the circumference, and adopt a double slider 53 structure, which effectively improves the bearing capacity of the guide device 5.

[0040] The displacement sensor 2 of the single-degree-of-freedom active adaptive force control flange adopts a high-precision grating sensor, including a patch bracket 21, a grating piece 22, a grating reader 23 and a grating reader mounting frame 24, which is used to detect the displacement of the moving platform 1 to achieve precise position control of the system. Among them, the grating reader 23 is fixedly connected to the outer cylindrical bracket 6 through the grating reader mounting frame 24, the grating piece 22 is attached to the patch bracket 21, and the patch bracket 21 is fixed on the moving platform 1 and moves with the moving platform 1.

[0041] Although the guide devices 5 and mechanical springs 3 used in this embodiment are three and evenly distributed at intervals of 120° along the circumference, those skilled in the art will appreciate that other numbers of guide devices 5 and mechanical springs 3 may also be used, as well as non-uniform arrangements.

[0042] In addition, those skilled in the art will appreciate that pneumatic components such as cylinders and artificial muscles may also be used as alternatives to the air springs in this embodiment, and that pneumatic components such as cylinders and artificial muscles should also be within the scope of protection of this patent.

[0043] The above embodiments describe the technical solutions of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A single-degree-of-freedom active adaptive force control flange for an industrial robot, mainly comprising a fixed platform (9), a moving platform (1), a linear motor (4), an air spring (8) and a guide device (5); wherein: The invention comprises an inner cylindrical support (7) and an outer cylindrical support (6) which are coaxially nested and installed, wherein the guide device (5) is arranged between the outer side wall of the inner cylindrical support (7) and the inner side wall of the outer cylindrical support (6); one end of the outer cylindrical support (6) has an opening for accommodating the inner cylindrical support (7), and the other end is fixedly connected to the fixed platform (9); the inner cylindrical support (7) is located at the inner end of the outer cylindrical support (6), and the air spring (8) is arranged between the inner cylindrical support (7) and the fixed platform (9); the outer end of the inner cylindrical support (7) is fixedly connected to the moving platform (1); the linear motor (4) comprises a motor stator (41), a permanent magnet ring (42) and a motor mover (43); the motor stator (41) is installed at the opening of the outer cylindrical support (6); the motor mover (43) is installed on the inner side of the moving platform (1) and is arranged coaxially with the inner cylindrical support (7); The open side of the outer cylindrical bracket (6) has three mounting brackets spaced 120 degrees apart, and the slider (53) in the guide device (5) is connected to the mounting bracket; the inner cylindrical bracket (7) has three pin brackets spaced 120 degrees apart at a location inside the outer cylindrical bracket (6), and the guide rail (52) in the guide device (5) is connected to the pin bracket; The inner cylindrical bracket (7) has a hollow structure between the pin brackets; the outer cylindrical bracket (6) has a hollow structure between the mounting brackets.

2. The single-degree-of-freedom active adaptive force control flange according to claim 1, characterized in that: A displacement sensor (2) for detecting the displacement of a moving platform (1) and a pressure sensor for detecting the actual contact force of an end-actuating tool are provided; the displacement sensor (2) and the pressure sensor feed back actual measurement values ​​to a controller, and the controller adjusts the current in a linear motor (4) to adjust the force deviation between the actual contact force and the desired force.

3. The single-degree-of-freedom active adaptive force control flange according to claim 1, characterized in that: The guide devices (5) are evenly spaced at intervals of 120° along the circumference, and each guide rail (52) adopts a double slider (53) structure.

4. The single-degree-of-freedom active adaptive force control flange according to claim 1, characterized in that: The air spring (8) and the linear motor (4) are coaxially mounted and are respectively located at two ends of the inner cylindrical support (7).

5. The single-degree-of-freedom active adaptive force control flange according to claim 1, characterized in that: The motor stator (41) has a circular groove, and inner and outer radiating permanent magnet rings (42) are provided on the inner and outer walls of the circular groove; the motor mover (43) is embedded in the circular ring formed between the inner and outer radiating permanent magnet rings (42); the motor mover (43) forms a bilateral air gap with the inner and outer radiating permanent magnet rings (42), and interacts with the permanent magnet rings (42).

6. The single-degree-of-freedom active adaptive force control flange according to claim 1, characterized in that: A mechanical spring (3) is provided between the moving platform (1) and the outer cylindrical support (6).

7. The single-degree-of-freedom active adaptive force control flange according to claim 6, characterized in that: The mechanical springs (3) are multiple in number and are evenly distributed along the circumference of the moving platform (1) and the outer cylindrical support (6).

8. The single-degree-of-freedom active adaptive force control flange according to claim 2, characterized in that: The displacement sensor (2) is a high-precision grating sensor, comprising a patch bracket (21), a grating sheet (22), a grating head (23) and a grating head mounting frame (24); the grating head (23) is fixedly connected to the outer cylindrical bracket (6) via the grating head mounting frame (24); the grating sheet (22) is attached to the patch bracket (21), and the patch bracket (21) is fixed to the moving platform (1) and moves with the moving platform (1).

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