Aerodynamic force-controlled actuator, robot having the same, and polishing method

Abstract

The application discloses a pneumatic force control actuator, a robot provided with the same and a polishing method. The pneumatic force control actuator comprises a mounting plate, a double-acting cylinder, an electric proportional valve group, a controller and a shaft coaxially distributed with a piston rod of the double-acting cylinder, a floating joint, a three-axis force sensor and a pneumatic polishing head. The double-acting cylinder is mounted on the mounting plate and is arranged with the piston rod downward. Two electric proportional valves of the electric proportional valve group are respectively connected with a rodless cavity and a rod cavity of the double-acting cylinder. The top end of the shaft is connected with the piston rod through the floating joint, and the bottom end of the shaft is connected with the three-axis force sensor. The pneumatic polishing head is connected with the three-axis force sensor through a shaft coupling. The three-axis force sensor is electrically connected with the controller, and the controller is electrically connected with the electric proportional valve group. The double-acting cylinder and the two electric proportional valves are adopted to accurately control and quickly adjust small contact force, meet the requirement of the force / heat sensitive characteristics of organic glass and other materials and avoid surface burn.

Description

A pneumatically controlled actuator, a robot with the same, and a polishing method. Technical Field

[0001] This invention relates to the field of robotic automated precision machining technology, and more specifically to a pneumatic control actuator, a robot having the same actuator, and a polishing method. Background Technology

[0002] In the fields of aerospace and precision optics manufacturing, polishing complex curved transparent components (such as aircraft canopies and high-precision lenses) places extremely high demands on surface integrity and optical performance. Materials such as PMMA (polymethyl methacrylate), while possessing excellent light transmittance, exhibit significant force / heat sensitivity. Excessive contact force can easily induce microcracks, while excessive frictional temperature rise can lead to surface softening or even burning. Traditional manual polishing relies on worker experience, resulting in low efficiency and poor consistency, making it difficult to meet the large-scale demands of high-precision curved surface processing.

[0003] With development, existing robotic polishing technology has solved the automation problem to some extent, but some key issues remain unresolved: 1) Insufficient precision in controlling minute contact forces. For example, conventional pneumatic actuators use single-acting cylinders or airbags for drive, which are limited by the single-chamber air pressure adjustment range, making it difficult to achieve precise control of minute forces at the ±0.5N level; 2) In the polishing of complex curved surfaces, the component of tool gravity changes dynamically with the pose, and existing solutions lack real-time pose detection and compensation mechanisms, resulting in significant fluctuations in contact force.

[0004] Therefore, providing a high-precision pneumatic control actuator, a robot with it, and a polishing method are problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a pneumatically controlled actuator, a robot having the same, and a polishing method, which achieves precise control of small contact force, ensuring that the processing requirements of the force / heat sensitive characteristics of plexiglass are met while improving polishing efficiency, surface integrity, and optical performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A pneumatically controlled actuator includes a mounting plate, a double-acting cylinder, an electro-proportional valve assembly, a controller, a shaft coaxially distributed with the piston rod of the double-acting cylinder, a floating joint, a triaxial force sensor, and a pneumatic grinding head. The double-acting cylinder is mounted on the mounting plate with the piston rod facing downwards. The two electro-proportional valves of the electro-proportional valve assembly are respectively connected to the rodless chamber and the rod chamber of the double-acting cylinder. The top end of the shaft is connected to the piston rod via the floating joint, and the bottom end of the shaft is connected to the triaxial force sensor. The pneumatic grinding head is connected to the triaxial force sensor via a coupling. The triaxial force sensor is electrically connected to the controller, and the controller is electrically connected to the electro-proportional valve assembly.

[0008] By adopting the above technical solutions, the beneficial effects of the present invention are as follows:

[0009] Employing a double-acting cylinder and two electric proportional valves, it can precisely control and quickly adjust small contact forces to meet the force / heat sensitive characteristics of materials such as plexiglass, thus avoiding surface burns.

[0010] Furthermore, it also includes multiple guide shafts and a support plate. The multiple guide shafts are distributed circumferentially along the double-acting cylinder and parallel to the shaft. Each guide shaft is connected to the mounting plate near its top end via a guide sleeve. The support plate is located between the floating joint and the triaxial sensor, and the support plate is horizontally mounted on the multiple guide shafts near their bottom ends via multiple linear bearings.

[0011] The beneficial effects of adopting the above-mentioned further technical solution are that it can limit the radial runout of the shaft, ensure the linearity of axial movement, withstand the torque generated by the change of surface curvature during polishing, and avoid the transmission structure from jamming.

[0012] Furthermore, the shaft is a ball spline shaft.

[0013] The beneficial effects of adopting the above-mentioned further technical solution are that the axial thrust of the cylinder is accurately transmitted to the polishing tool, while the radial torque (such as the lateral force during the polishing process) is borne by the ball spline structure, preventing tool wobble. The ball circulation design makes the axial motion repeatability accuracy reach ±0.02mm, avoiding force control fluctuations caused by mechanical backlash.

[0014] Furthermore, the pneumatic grinding head includes a pneumatic grinding head body and a flexible polishing disc, the flexible polishing disc being engaged with the pneumatic grinding head body.

[0015] The beneficial effect of adopting the above-mentioned further technical solution is that it facilitates the rapid switching between sandpapers of different grit sizes.

[0016] A robot includes a robot body and a pneumatic control actuator as described above, wherein the mounting plate is mounted on the output end of the robot body.

[0017] By adopting the above technical solutions, the beneficial effects of the present invention are as follows:

[0018] The pneumatic actuator, in conjunction with the robot's automatic polishing system, ensures stable normal contact force and uniform material removal during the polishing process, significantly improving the surface integrity and optical performance of complex curved transparent parts.

[0019] A polishing method, based on the robot described above, includes the following steps:

[0020] 1) The robot body drives the pneumatic actuator to move along a preset trajectory. During this process, the three-axis force sensor detects the actual contact force F in real time. n (t), according to the contact force error formula e(t)=F0-F n (t) Calculate e(t), where e(t) is the contact force error and F0 is the target contact force;

[0021] 2) According to the PID control equation The controller output signal is obtained, where u(t) is the controller output signal and k p k i k d These are the proportional, integral, and differential coefficients, respectively.

[0022] 3) Upon receiving the control output signal, the electro-proportional valve group adjusts its voltage, thereby regulating the pressure difference between the rodless and rod chambers of the double-acting cylinder. Ultimately, this regulates the output force of the double-acting cylinder, ensuring the actual contact force tracks the target contact force. The equation for the gas flow rate and input voltage of the electro-proportional valve group is as follows: u is the input voltage of the electro-proportional valve group, k1 and k2 are the valve body characteristic coefficients, and F c The output force of a double-acting cylinder is given by the formula F, which expresses the relationship between the output force and the pressure difference. c =P d ·A d -P f ·A f , where P d P is the pressure in the rodless chamber. f For the rod chamber air pressure, A d A rodless cavity effective section machine, A f Given the effective cross-sectional area of ​​the rod-side cavity, the pressure difference between the rodless and rod-side cavities is calculated using the formula ΔP = P0. d -P f .

[0023] By adopting the above technical solutions, the beneficial effects of the present invention are as follows:

[0024] Data from a triaxial force sensor is collected, and a control signal is output to an electro-proportional valve group. The contact force error is calculated in real time, and the air pressure difference ΔP is dynamically adjusted to achieve a closed-loop force control, so that the actual contact force is stabilized at the target contact force F0±0.5N. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 is a schematic diagram of the overall structure of a pneumatic control actuator provided by the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] As shown in Figure 1, this embodiment of the invention discloses a pneumatic control actuator, including a mounting plate 1, a double-acting cylinder 2, an electro-proportional valve group, a controller, and a shaft 3, a floating joint 4, a triaxial force sensor 5, and a pneumatic grinding head 6, all coaxially distributed with the piston rod of the double-acting cylinder 2. The double-acting cylinder 2 is mounted on the mounting plate 1 with its piston rod facing downwards. The two electro-proportional valves of the electro-proportional valve group are respectively connected to the rodless chamber and the rod chamber of the double-acting cylinder 2. The top end of the shaft 3 is connected to the piston rod through the floating joint 4, which allows a deflection angle of ±2° to compensate for installation errors. The bottom end of the shaft 3 is connected to the triaxial force sensor 5. In this embodiment, the shaft 3 and the triaxial force sensor 5 are connected through a flange. The pneumatic grinding head 6 is connected to the triaxial force sensor 5 through a coupling, wherein the coupling adopts an elastic cloverleaf structure to reduce vibration transmission. The triaxial force sensor 5 is electrically connected to the controller, and the controller is electrically connected to the electro-proportional valve group. This invention employs a double-acting cylinder 2 and two electric proportional valves, which can precisely control and quickly adjust small contact forces to meet the force / heat sensitive characteristics of materials such as plexiglass and avoid surface burns.

[0029] It is worth noting that the double-acting cylinder 2 of the present invention is designed for low friction. Its specific working principle is as follows: linear thrust or pull is generated by the air pressure difference between the rodless chamber and the rod chamber (the chamber containing the piston rod is called the rod chamber, while the chamber without the piston rod is called the rodless chamber), thereby realizing the dynamic adjustment of the polishing contact force. The two chambers can be adjusted independently, breaking through the limitation of the single-chamber force control range, and achieving a precision of ±0.5N within the air pressure range of 0.1-0.7MPa.

[0030] To further optimize the technical solution of the present invention, it also includes multiple guide shafts 7 and a support plate 8. The multiple guide shafts 7 are distributed circumferentially along the double-acting cylinder 2 and parallel to the shaft. Each guide shaft 7 is connected to the mounting plate 1 near the top end through a guide sleeve. The support plate 8 is located between the floating joint 4 and the triaxial sensor 5. The floating joint 4 or the shaft 3 passes through the support plate 8, and the support plate 8 is horizontally mounted on the multiple guide shafts 7 near the bottom end through multiple linear bearings. This can limit the radial runout of the shaft 3 (≤0.01mm), ensure the linearity of axial movement, withstand the torque generated by the change of surface curvature during the polishing process, and avoid the transmission structure from jamming.

[0031] To further optimize the technical solution of the present invention, shaft 3 is a ball spline shaft, which can accurately transmit the axial thrust of the double-acting cylinder 2 to the polishing tool. At the same time, the ball spline structure can withstand radial torque (such as lateral force during the polishing process) to prevent tool wobble. The ball circulation design makes the axial motion repeatability accuracy reach ±0.02mm, avoiding force control fluctuations caused by mechanical backlash.

[0032] To further optimize the technical solution of the present invention, the pneumatic grinding head 6 includes a pneumatic grinding head body and a flexible polishing disc, which drives the flexible polishing disc to rotate and remove materials by combining sandpaper or polishing liquid. The flexible polishing disc is engaged with the pneumatic grinding head body, which facilitates the rapid switching of sandpaper with different grit sizes.

[0033] This invention also discloses a robot, including a robot body and the pneumatic actuator described above, with a mounting plate 1 installed at the output end of the robot body. The pneumatic actuator of this invention, in conjunction with the robot body's automatic polishing system, ensures stable normal contact force and uniform material removal during polishing, significantly improving the surface integrity and optical performance of complex curved transparent parts.

[0034] This invention also discloses a polishing method based on the robot described above, comprising the following steps:

[0035] 1) The robot body drives the pneumatic actuator to move along a preset trajectory. During this process, the three-axis force sensor 5 detects the actual contact force F in real time. n (t), according to the contact force error formula e(t)=F0-F n(t) Calculate e(t), where e(t) is the contact force error and F0 is the target contact force;

[0036] 2) According to the PID control equation The controller output signal is obtained, where u(t) is the controller output signal and k p k i k d These are the proportional, integral, and differential coefficients, respectively.

[0037] 3) Upon receiving the control output signal, the electro-proportional valve group adjusts its voltage, thereby regulating the pressure difference between the rodless and rod chambers of the double-acting cylinder 2. Ultimately, this regulates the output force of the double-acting cylinder 2, ensuring the actual contact force tracks the target contact force. The equation for the gas flow rate and input voltage of the electro-proportional valve group is as follows: u is the input voltage of the electro-proportional valve group, k1 and k2 are the valve body characteristic coefficients, and F c The output force of a double-acting cylinder is given by the formula F, which expresses the relationship between the output force and the pressure difference. c =P d ·A d -P f ·A f , where P d P is the pressure in the rodless chamber. f For the rod chamber air pressure, A d A rodless cavity effective section machine, A f Given the effective cross-sectional area of ​​the rod-side cavity, the pressure difference between the rodless and rod-side cavities is calculated using the formula ΔP = P0. d -P f .

[0038] This invention collects data from a triaxial force sensor 5, outputs control signals to an electro-proportional valve group, calculates the contact force error in real time, and dynamically adjusts the air pressure difference ΔP to achieve a closed-loop force control (the air pressure difference ΔP is dynamically adjusted through the electro-proportional valve group, which directly affects the cylinder output force Fc; at the same time, the rate of change of the output force is fed back to the air pressure difference adjustment process, forming a closed-loop control), so that the actual contact force is stabilized at the target contact force F0±0.5N.

[0039] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0040] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A polishing method, characterized in that, Based on a robot, the robot includes a robot body and a pneumatic control actuator. The pneumatic control actuator includes a mounting plate, a double-acting cylinder, an electro-proportional valve assembly, a controller, and a shaft coaxially distributed with the piston rod of the double-acting cylinder, a floating joint, a three-axis force sensor, and a pneumatic grinding head. The mounting plate is installed at the output end of the robot body. The double-acting cylinder is mounted on the mounting plate with the piston rod facing downwards. The two electro-proportional valves of the electro-proportional valve assembly are respectively connected to the rodless chamber and the rod chamber of the double-acting cylinder. The top end of the shaft is connected to the piston rod through the floating joint, and the bottom end of the shaft is connected to the three-axis force sensor. The pneumatic grinding head is connected via a coupling. The pneumatic actuator is connected to the triaxial force sensor; the triaxial force sensor is electrically connected to the controller, and the controller is electrically connected to the electro-proportional valve group; the pneumatic actuator also includes multiple guide shafts and a support plate, the multiple guide shafts are distributed circumferentially along the double-acting cylinder and parallel to the shaft, and each guide shaft is connected to the mounting plate near its top end via a guide sleeve; the support plate is located between the floating joint and the triaxial force sensor, and the support plate is horizontally mounted near the bottom end of the multiple guide shafts via multiple linear bearings; the polishing method includes the following steps: 1) The robot body drives the pneumatic actuator to move along a preset trajectory, during which the triaxial force sensor detects the actual contact force in real time. According to the contact force error formula Calculate ,in 1) Target contact force; 2) According to the PID control equation The controller output signal is obtained, where Output signal to the controller 、 、 These are the proportional, integral, and derivative coefficients, respectively; 3) The electro-proportional valve group receives the control output signal, adjusts the voltage of the electro-proportional valve group, adjusts the pressure difference between the rodless and rod chambers of the double-acting cylinder, and finally adjusts the output force of the double-acting cylinder so that the actual contact force tracks the target contact force. The equation for the gas flow rate and input voltage of the electro-proportional valve group is: ， Input voltage for the electro-proportional valve assembly. 、 This is the valve body characteristic coefficient. The output force of a double-acting cylinder is given by the following formula: ,in The pressure in the rodless chamber is... The pressure in the rod chamber is... Effective cross-section machine The effective cross-sectional area of ​​the rod-type cavity is given by the formula for the pressure difference between the rodless and rod-type cavities. 。 2. The polishing method according to claim 1, characterized in that, The shaft is a ball spline shaft.

3. The polishing method according to claim 2, characterized in that, The pneumatic grinding head includes a pneumatic grinding head body and a flexible polishing disc, the flexible polishing disc being snapped into the pneumatic grinding head body.

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