CN105173129B - Triaxial air bearing table leveling method - Google Patents

Abstract

The invention discloses a three-axis air bearing platform leveling system and method, wherein the three-axis air bearing platform leveling system includes three sets of flywheel modules, three sets of weight balance modules and four sets of air injection modules, the flywheel module and the weight The balance modules are all corresponding to the X, Y, and Z axes, and are arranged orthogonally in pairs. Four sets of jet modules are set on the edge of the three-axis air bearing table in the directions of the positive X axis, negative X axis, positive Y axis and negative Y axis; the flywheel The module is used to maintain the attitude of the air bearing platform, and the jet module is used to unload the flywheel module. The weight balance module is used to adjust the center of gravity of the air bearing platform. According to the magnitude and direction of the acceleration of the flywheel module, the direction and the amount of movement are automatically selected to achieve fast and accurate automatic center of gravity balance. The invention has the advantages of simple structure, convenient operation and low cost, can realize rapid and accurate balance, and breaks through the previous limitation that center of gravity adjustment is only limited to X and Y planes.

Description

A method for leveling a three-axis air bearing table

technical field

The invention relates to measurement technology, in particular to a leveling system and method for a three-axis air bearing platform.

Background technique

The air-floating table relies on compressed air to form an air film between the air-floating bearing and the bearing seat, so that the experimental table is floated, so as to achieve a relatively frictionless relative motion condition, thereby simulating the satellite in space with a small disturbance moment. Mechanics environment. As a satellite motion simulator, the three-axis air bearing platform supported by spherical air bearings can not only simulate the attitude movement required in the three-axis direction, but also simulate the three-axis attitude coupling dynamics of the satellite. The full physical simulation through the air bearing table plays an important role, and it is an indispensable tool for program demonstration and functional verification. Simulation practice has proved that the use of air bearing platform for simulation not only plays an important role in the verification of satellite attitude control system, but also can significantly improve the cost-effectiveness of satellites, reduce risks, and shorten the development cycle.

In order to simulate the attitude movement of the satellite on the ground, the rotation center of the three-axis air bearing should coincide with the center of mass of the platform body, otherwise, an unbalanced moment will be generated, which will affect the effect of the simulation test. At present, there are mainly two ways of trimming the air bearing table: automatic and manual. China Invention Patent No.: 200610009797,7, the patent name is: the center of mass adjustment device for the external load of the air flotation table, which adjusts the center of mass of the turntable by adjusting the bolt and nut mechanism installed on the air flotation table. There are two working modes: manual and electric. This invention Only one adjustment device is given, no specific balancing method is involved. Li Yanbin, Baotou Steel, Wang Zuwen, Lu Yandong, etc. in the paper "Dynamic Modeling of Automatic Balance System of Three-DOF Air Bearing Platform" (see "Chinese Journal of Inertial Technology", 2005, Volume 13, Issue 5, Pages 83-87) , the automatic balancing device of the three-axis air bearing table is given theoretically, and the specific implementation method is not given, which is difficult to be practical in engineering. China Invention Patent No. 200910071536.1, the patent name is: three-axis air bearing balancing method and its device. The leveling of the center of gravity is achieved through the momentum wheel, the motor and the mass slider, but it is only limited to the x and y axes, and it is not suitable for the leveling of the z axis.

Contents of the invention

The technical problem to be solved by the present invention is to provide a three-axis air bearing leveling system and method with simple structure, convenient operation, full automatic and low cost for the defects involved in the background technology.

The present invention adopts the following technical solutions for solving the problems of the technologies described above:

A three-axis air bearing platform leveling system, including a three-axis air bearing platform, first to third flywheel modules, first to third weight balance modules, first to fourth air jet modules, gyro, inclination sensor and control module;

The first to third flywheel modules are arranged in pairs on the three-axis air bearing platform, and are used to adjust the X-axis, Y-axis, and Z-axis of the three-axis air bearing platform with the rotation center as the origin. axis attitude;

The first to third weight balance modules are arranged in pairs on the three-axis air-floating platform in twos and orthogonally, and are used to adjust the X-axis and Y-axis of the three-axis air-floating platform with the center of rotation as the origin respectively. , Z-axis balance;

The first to fourth air injection modules correspond to the positive X axis, negative X axis, positive Y axis and negative Y axis arranged on the edge of the three-axis air bearing table, and are used to unload the first to third air bearing modules respectively. flywheel module;

The gyroscope is used to measure the angular velocity of the three-axis air bearing table in the directions of the X-axis, Y-axis and Z-axis with the center of rotation as the origin;

The inclination sensor is used to measure the inclination angles of the three-axis air bearing table in the X-axis, Y-axis, and Z-axis directions with the center of rotation as the origin;

The control module is used to control the first to third flywheel modules, the first to third weight balance modules and the first to fourth air jet modules to work according to the measurement results of the gyro and the inclination sensor.

As a further optimization scheme of the three-axis air bearing platform leveling system of the present invention, the weight balance module includes a slide rail, a slider, a lead screw, a mass block, a reduction device and a motor;

The slider is provided with a nut matched with the lead screw, which is controlled to slide on the slide rail by the rotation of the lead screw;

The mass block is arranged on the slider;

The output end of the motor is connected to the lead screw through a reduction gear, and is used to control the forward or reverse rotation of the lead screw.

As a further optimization scheme of the three-axis air bearing platform leveling system of the present invention, the first to fourth air injection modules all include first to fourth air injection units;

The first air injection unit and the second air injection unit in the first to second air injection modules are arranged along the Y axis, and the air injection directions are respectively the positive Y axis and the negative Y axis; the third air injection unit and the fourth air injection unit are arranged along the Z axis , and the jet directions are positive Z axis and negative Z axis respectively;

The first air injection unit and the second air injection unit in the third to fourth air injection modules are arranged along the X axis, and the air injection directions are respectively the positive X axis and the negative X axis; the third air injection unit and the fourth air injection unit are arranged along the Z axis , and the jet directions are positive Z-axis and negative Z-axis respectively.

The present invention also discloses a leveling method based on the three-axis air bearing leveling system, comprising the following steps:

Step 1), the three-axis air bearing table is stationary horizontally;

Step 2), release the three-axis air bearing, and measure the angular acceleration of the three-axis air bearing around the X and Y axes at this time;

Step 3), calculate the acceleration of the first flywheel module and the second flywheel module according to the ratio of the inertia of the three-axis air bearing table surface to the flywheel inertia of the flywheel module and the angular acceleration measured in step 2);

Step 4), control the first flywheel module and the second flywheel module to accelerate the rotation in the same direction as the three-axis air bearing platform rotates around the X and Y axes;

Step 5), when the speed of the first flywheel module or the second flywheel module exceeds the preset speed threshold, control its corresponding air injection module to generate torque in the same direction as its torque, so as to unload the flywheel module and ensure that the current three-axis air The floating platform maintains a horizontal attitude;

Step 6), measure the magnitude and direction of the torque generated by the first flywheel module and the second flywheel module, and adjust the position of the weights in the first weight balance module and the second weight balance module according to the measurement results, so that the first The flywheel module and the second flywheel module no longer generate angular acceleration;

Step 7), controlling the first to fourth jet modules to unload the first to third flywheel modules;

Step 8), control the first flywheel module, and any group of flywheel modules in the second flywheel module rotates at a preset acceleration to make the three-axis air bearing table tilt;

Step 9), measure the angular acceleration of the three-axis air bearing table;

Step 10), adjust the position of the weights in the third weight balance module according to the difference between the angular acceleration of the table top measured in step 9) and the preset angular acceleration threshold, so that the air bearing table can be in each flywheel module Balance in any posture when it is stopped or running at a constant speed.

Compared with the prior art, the present invention adopts the above technical scheme and has the following technical effects:

1. Simple structure, convenient operation and low cost;

2. It can realize online measurement and adjustment, and realize fast and accurate automatic balance;

3. It breaks through the limitation that the adjustment of the center of gravity in the past is only limited to the X and Y planes, and truly realizes the three-axis leveling of the center of gravity of the three-axis air bearing table.

Description of drawings

Fig. 1 is a weight system;

Figure 2 is a top view of the table top layout of the air bearing table (sensor and weight system layout);

Figure 3 is a bottom view of the air bearing table layout (flywheel module layout);

Fig. 4 is a schematic structural view of the first to fourth air injection modules in the present invention.

In the figure, 1. slider bracket, 2. quality block, 3. slide rail, 4. lead screw, 5. slider, 6. deceleration device, 7. motor, 8. first weight balance module, 9. One jet module, 10, the third jet module, 11, the second weight balance module, 12, the inclination sensor, 13, the third weight balance module, 14, the second jet module, 15, the gyroscope combination, 16, the first Four jet modules, 17, first flywheel module, 18, second flywheel module, 19, third flywheel module, 20, motor driver, 21, second jet unit, 22, third jet unit, 23, jet module support, 24, the first jet unit, 25, the fourth jet unit.

detailed description

Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:

The three-axis air bearing table is an important means to carry out the full physical simulation of the satellite on the ground. Because of its nearly frictionless characteristics, the full physical model is used instead of the calculation model, which makes its simulation results have important significance. However, in order to carry out accurate simulation, we must ensure that the center of gravity of the system coincides with the center of rotation completely before the start of the simulation experiment. Only in this way can the interference torque caused by the center of gravity be avoided from affecting the experimental results. In the existing articles and patents, most of them only discussed the possibility of leveling the center of gravity from a theoretical point of view, but did not provide a practical engineering solution and device for three-axis leveling. Starting from this, the present invention proposes a simple and convenient device and adjustment method suitable for leveling the center of gravity of three axes.

As shown in Figures 2 to 3, the present invention discloses a three-axis air bearing platform leveling system, which includes a three-axis air bearing platform, first to third flywheel modules, first to third weight balance modules, 1st to 4th jet module, gyroscope, inclination sensor and control module;

The first to third flywheel modules are arranged in pairs on the three-axis air bearing platform, and are used to adjust the X-axis, Y-axis, and Z-axis of the three-axis air bearing platform with the rotation center as the origin. axis attitude;

The first to third weight balance modules are arranged in pairs on the three-axis air-floating platform in twos and orthogonally, and are used to adjust the X-axis and Y-axis of the three-axis air-floating platform with the center of rotation as the origin respectively. , Z-axis balance;

The first to fourth air injection modules correspond to the positive X axis, negative X axis, positive Y axis and negative Y axis arranged on the edge of the three-axis air bearing table, and are used to unload the first to third air bearing modules respectively. flywheel module;

The gyroscope is used to measure the angular velocity of the three-axis air bearing table in the directions of the X-axis, Y-axis and Z-axis with the center of rotation as the origin;

The inclination sensor is used to measure the inclination angles of the three-axis air bearing table in the X-axis, Y-axis, and Z-axis directions with the center of rotation as the origin;

The control module is used to control the first to third flywheel modules, the first to third weight balance modules and the first to fourth air jet modules to work according to the measurement results of the gyro and the inclination sensor.

As shown in Figure 1, the weight balance module includes a slide rail, a slide block, a leading screw, a quality block, a reduction gear and a motor;

The slider is provided with a nut matched with the lead screw, which is controlled to slide on the slide rail by the rotation of the lead screw;

The mass block is arranged on the slider;

The output end of the motor is connected to the lead screw through a reduction gear, and is used to control the forward or reverse rotation of the lead screw.

As shown in Figure 4, the first to fourth air injection modules all include first to fourth air injection units;

The first air injection unit and the second air injection unit in the first to second air injection modules are arranged along the Y axis, and the air injection directions are respectively the positive Y axis and the negative Y axis; the third air injection unit and the fourth air injection unit are arranged along the Z axis , and the jet directions are positive Z axis and negative Z axis respectively;

The first air injection unit and the second air injection unit in the third to fourth air injection modules are arranged along the X axis, and the air injection directions are respectively the positive X axis and the negative X axis; the third air injection unit and the fourth air injection unit are arranged along the Z axis , and the jet directions are positive Z axis and negative Z axis respectively.

The jet units in the jet module are all fixed by the jet module bracket.

The present invention also discloses a leveling method based on the above-mentioned three-axis air bearing platform, comprising the following steps:

Step 1), the three-axis air bearing table is stationary horizontally;

Step 2), release the three-axis air bearing, and measure the angular acceleration of the three-axis air bearing around the X and Y axes at this time;

Step 3), calculate the acceleration of the first flywheel module and the second flywheel module according to the ratio of the inertia of the three-axis air bearing table surface to the flywheel inertia of the flywheel module and the angular acceleration measured in step 2);

Step 4), control the first flywheel module and the second flywheel module to accelerate the rotation in the same direction as the three-axis air bearing platform rotates around the X and Y axes;

Step 5), when the speed of the first flywheel module or the second flywheel module exceeds the preset speed threshold, control its corresponding air injection module to generate torque in the same direction as its torque, so as to unload the flywheel module and ensure that the current three-axis air The floating platform maintains a horizontal attitude;

Step 6), measure the magnitude and direction of the torque generated by the first flywheel module and the second flywheel module, and adjust the position of the weights in the first weight balance module and the second weight balance module according to the measurement results, so that the first The flywheel module and the second flywheel module no longer generate angular acceleration;

Step 7), controlling the first to fourth jet modules to unload the first to third flywheel modules;

Step 8), control the first flywheel module, and any group of flywheel modules in the second flywheel module rotates at a preset acceleration to make the three-axis air bearing table tilt;

Step 9), measure the angular acceleration of the three-axis air bearing table;

Step 10), adjust the position of the weights in the third weight balance module according to the difference between the angular acceleration of the table top measured in step 9) and the preset angular acceleration threshold, so that the air bearing table can be in each flywheel module Balance in any posture when it is stopped or running at a constant speed.

During the leveling process, the third flywheel module is mainly used to offset the external disturbance torque to ensure the effective implementation of the leveling process.

The working principle of the present invention is as follows:

After the three-axis air-floor table has been roughly trimmed (or there is a slight unbalance in the three-axis air-floor table due to the slight change in the center of mass caused by air injection and other reasons after the three-axis air-floor table is trimmed), the size of the three-axis air-floor table is different by controlling each flywheel module. Acceleration to generate torque of different magnitudes. The inclination angle of the entire platform can be read through the horizontal inclination angle, and the attitude information acts on the corresponding flywheel module through an algorithm to generate a corresponding moment, so that the attitude of the three-axis air bearing platform remains unchanged. Then, the adjustment of the center of mass of the entire three-axis air bearing table on the x and y planes is realized by adjusting the positions of the weights in the first weight balance module and the second weight balance module. After the adjustment of the center of mass of the X and Y planes is completed, a given acceleration is applied to the flywheel. Since the moment of inertia of the table is known, the theoretical value of the rotation speed of the table can be obtained. By comparing the difference between the actual value and the theoretical value, we can determine the direction in which the Z-axis weight should move, and adjust the position of the weight until the air bearing table is stable in a non-horizontal position. So far, we have realized the automatic online adjustment of the center of mass of the three-axis air bearing table.

The structural design of the weight balance module is shown in Figure 1. The motor controls the movement of the weight by driving the lead screw. The base plays the role of fixing the weight, so that the rotation of the lead screw can drive the weight to move back and forth, and the motor is connected with the lead screw through the reducer to drive the lead screw to rotate. The weight balance module is installed on the horizontal plane of the three-axis air bearing table, and placed parallel to the X and Y axes respectively.

There are three groups of flywheel modules, two groups of rotation axes are parallel to the X and Y axes of the three-axis air bearing table, and the rotation axis of the other group is parallel to the Z axis, and they are all installed on the horizontal plane of the three-axis air bearing table, placed orthogonally . When the center of gravity needs to be adjusted, stop other tests and keep the control of the flywheel module on the three-axis air bearing table. The control goal of the first stage is to keep the horizontal attitude of the three-axis air bearing platform unchanged. Keep the three-axis air bearing table static, if the center of gravity of the three-axis air bearing table does not coincide with the rotation center of the three-axis air bearing table, the three-axis air bearing table will shake in one direction, and the flywheel module should keep the three-axis air bearing table stationary Attitude, its speed will increase in the same direction. When correcting the horizontal attitude of the air bearing table, the tilt of the air bearing table caused by the deviation between the center of gravity and the center of rotation is decoupled on the X and Y axes. Therefore, we can correct the center of gravity through two weight balance modules placed on the X-axis and Y-axis respectively. The direction of rotation of the flywheel and the direction of movement of the weights are based on the attitude data obtained by the sensors. The flywheel module of the Z axis is mainly used to offset the external disturbance torque to ensure the effective implementation of the leveling process.

Assume that the center of gravity of the air bearing is located in the positive direction of the X-axis and the positive direction of the Y-axis of the rotation center. Take the leveling of the X axis as an example. Assuming that the current center of gravity is located in the positive direction of the X-axis of the rotation center, the whole platform will tilt in the positive direction of the X-axis. In order to eliminate this tilting tendency, the flywheel will rotate in the same direction according to the acceleration of the table body to the positive direction of the X-axis, and at the same time, the weight will be adjusted by moving in the opposite direction at a certain speed according to the acceleration of the flywheel center of gravity. Since the offset of the center of gravity in the positive X direction is reduced, the tendency of the table body to incline to the positive X direction will also be reduced, and at the same time the rotational acceleration of the flywheel and the moving speed of the weight will also be reduced, and eventually balance will be reached. The way of leveling the Y axis is the same. The leveling of the Z axis needs to be based on the leveling of the X and Y axes. When the X and Y axes are leveled, the platform will remain stationary in a horizontal position. At this time, a given acceleration is given to the flywheel, and since the inertia of the platform body is known, the platform body will also produce a specific acceleration and leave the horizontal state. At this time, if the center of mass is higher than the center of rotation, a moment will be generated to intensify the inclination of the table body. At this time, the sensor on the table will detect a larger angular velocity and angular acceleration. At this time, the flywheel will output the corresponding torque according to the angular acceleration of the table body, so as to stabilize the control body in a non-horizontal state, and adjust the weight mechanism of the Z axis in the -Z direction to reduce the center of mass in the +Z direction. offset. If the center of mass is lower than the center of rotation, there will be a tendency to tilt the body with a reduced moment. At this time, the sensor will detect angular velocity and angular acceleration smaller than the theoretical value. At this time, the flywheel will output the corresponding torque according to the angular acceleration of the table body, so as to stabilize the control body in a non-horizontal state, and adjust the weight mechanism of the Z axis in the +Z direction to reduce the center of mass in the -Z direction. offset. Repeat the above steps, and finally, the table body will be able to rest in a non-horizontal position when the flywheel module stops or rotates at a constant speed. So far, the adjustment of the center of mass of the air bearing table on the three axes is completed.

Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless defined as herein Explanation.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. A leveling method for a three-axis air bearing platform leveling system, characterized in that, the three-axis air bearing platform leveling system comprises a three-axis air bearing platform, first to third flywheel modules, first to third Three-weight balance module, first to fourth jet modules, gyroscope, inclination sensor and control module; The first to third flywheel modules are arranged in pairs on the three-axis air bearing platform, and are used to adjust the X-axis, Y-axis, and Z-axis of the three-axis air bearing platform with the rotation center as the origin. axis attitude; The first to third weight balance modules are arranged in pairs on the three-axis air-floating platform in twos and orthogonally, and are used to adjust the X-axis and Y-axis of the three-axis air-floating platform with the center of rotation as the origin respectively. , Z-axis balance; The first to fourth air injection modules correspond to the positive X axis, negative X axis, positive Y axis and negative Y axis arranged on the edge of the three-axis air bearing table, and are used to unload the first to third air bearing modules respectively. flywheel module; The gyroscope is used to measure the angular velocity of the three-axis air bearing table in the directions of the X-axis, Y-axis and Z-axis with the center of rotation as the origin; The inclination sensor is used to measure the inclination angles of the three-axis air bearing table in the X-axis, Y-axis, and Z-axis directions with the center of rotation as the origin; The control module is used to control the first to third flywheel modules, the first to third weight balance modules and the first to fourth air jet modules to work according to the measurement results of the gyro and the inclination sensor; The leveling method of described three-axis air bearing platform leveling system comprises the following steps: Step 1), the three-axis air bearing table is stationary horizontally; Step 2), release the three-axis air bearing, and measure the angular acceleration of the three-axis air bearing around the X and Y axes at this time; Step 3), calculate the acceleration of the first flywheel module and the second flywheel module according to the ratio of the inertia of the three-axis air bearing table surface to the flywheel inertia of the flywheel module and the angular acceleration measured in step 2); Step 4), control the first flywheel module and the second flywheel module to accelerate the rotation in the same direction as the three-axis air bearing platform rotates around the X and Y axes; Step 5), when the speed of the first flywheel module or the second flywheel module exceeds the preset speed threshold, control its corresponding air injection module to generate torque in the same direction as its torque, so as to unload the flywheel module and ensure that the current three-axis air The floating platform maintains a horizontal attitude; Step 6), measure the magnitude and direction of the torque generated by the first flywheel module and the second flywheel module, and adjust the positions of the weights in the first weight balance module and the second weight balance module according to the measurement results, so that the first The flywheel module and the second flywheel module no longer generate angular acceleration; Step 7), controlling the first to fourth jet modules to unload the first to third flywheel modules; Step 8), control the first flywheel module, and any group of flywheel modules in the second flywheel module rotates at a preset acceleration to make the three-axis air bearing table tilt; Step 9), measure the angular acceleration of the three-axis air bearing table; Step 10), adjust the position of the weights in the third weight balance module according to the difference between the angular acceleration of the table top measured in step 9) and the preset angular acceleration threshold, so that the air bearing table can be in each flywheel module Balance in any posture when it is stopped or running at a constant speed. 2. The leveling method of the three-axis air bearing leveling system according to claim 1, wherein the weight balance module comprises a slide rail, a slider, a screw, a mass, a reduction device and a motor; The slider is provided with a nut matched with the lead screw, which is controlled to slide on the slide rail by the rotation of the lead screw; The mass block is arranged on the slider; The output end of the motor is connected to the lead screw through a reduction gear, and is used to control the forward or reverse rotation of the lead screw. 3. The leveling method of the three-axis air bearing platform leveling system according to claim 1, wherein the first to fourth air injection modules all include first to fourth air injection units; The first air injection unit and the second air injection unit in the first to second air injection modules are arranged along the Y axis, and the air injection directions are respectively the positive Y axis and the negative Y axis; the third air injection unit and the fourth air injection unit are arranged along the Z axis , the air jet directions are positive Z-axis and negative Z-axis respectively; The first air injection unit and the second air injection unit in the third to fourth air injection modules are arranged along the X axis, and the air injection directions are respectively the positive X axis and the negative X axis; the third air injection unit and the fourth air injection unit are arranged along the Z axis , and the jet directions are positive Z axis and negative Z axis respectively.