On-orbit assembly robot ground test system and method based on air floating platform

Abstract

According to the on-orbit assembly robot ground test system and method based on the air floating platform, the air floating platform serves as a support, gravity unloading is provided through two air floating simulators floating on the platform, and a mechanical arm installed on one air floating simulator picks up the other air floating simulator; and enabling the large-tolerance butt joints which are respectively arranged on the flexible simulation piece cross beams of the two air floatation simulators to be close to each other until the butt joint is completed, so as to complete the verification of the related auxiliary butt joint capability of the space manipulator. In the process, the vertical rod of the flexible simulation piece is connected with the air floating simulator at the mounting end of the mechanical arm, and flexible damping simulation in the horizontal direction is provided. Different flexible simulation pieces are matched with the air flotation device, vertical gravity unloading, horizontal controllable force and torque control and flexible base damping disturbance in the mechanical arm actuation process are met at the same time, the in-orbit working condition of the space mechanical arm can be fully simulated, and the auxiliary butt joint capacity of the mechanical arm is verified.

Description

Technical Field

[0001] The present invention relates to a space robot ground test system and method based on an air floating platform, and is particularly suitable for ground verification of space robot related technologies operating on a flexible base in a scenario of on-orbit assembly of a large-area space structure. Background Art

[0002] An on-orbit assembly robot is a special robot used to connect different parts in a space orbit to build a new structure or unit body or other space facilities, or to recombine multiple structures. With the development of space on-orbit assembly robot technology, the demand for its test and verification is also growing. The main characteristics of its working conditions are the microgravity environment in which it is located and the disturbance of the flexible base caused by clinging to large space structures. At present, when verifying related technologies such as robot control, a test system based on a fixed base is generally used. For robots working in space environments such as on-orbit assembly robots, the cost of direct launch for on-orbit testing is too high, so it is necessary to simulate the space assembly working environment on the ground. The fixed base method cannot meet the requirements of its microgravity and flexible base working conditions, so it is necessary to design a test system that can achieve partial gravity unloading on the ground.

[0003] At present, when my country conducts ground tests on space mechanisms, in order to achieve gravity unloading in the vertical direction, most of them use hanging and air-floating platforms. When using a hanging test system, it is often applicable to large mechanisms with a small actuation range and slow movements. When facing the actuation test requirements of on-orbit assembly robots, there may be slow response to the movements. During the adjustment process, there are lateral force disturbances caused by the position of the slings and torsional torque interference caused by the ropes. It is not suitable for on-orbit assembly robot verification. Although traditional air-floating platforms can achieve gravity unloading in the vertical direction, they cannot provide controllable offset force and torque control and flexible base vibration damping in the horizontal direction during the on-orbit assembly process. They cannot truly reproduce the working conditions faced by on-orbit assembly robots and are difficult to meet the existing robot-related technical test requirements.

[0004] In summary, there is an urgent need to develop a ground test system suitable for on-orbit assembly robots that can simultaneously meet the requirements of vertical gravity unloading, horizontal controllable force and torque control, and flexible base damping disturbance during actuation. This system can improve the on-orbit robot's ability to pick up, drag, and dock components in space, and enhance the efficiency and accuracy of verification of related technologies for on-orbit assembly robots. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and provide a ground test system and method suitable for an on-orbit assembly robot, which simultaneously meets the working condition constraints of vertical gravity unloading, horizontal controllable force and torque control, and flexible base damping disturbance during actuation, and is used to realize ground testing of the on-orbit assembly docking assembly process.

[0006] The technical solution of the present invention is: an on-orbit assembly robot ground test system based on an air flotation platform, comprising: an air flotation platform, an air flotation simulator, a flexible simulation part, a robotic arm, a hand-eye recognition camera, a circumferential motion capture camera, an air supply device and a large tolerance docking joint;

[0007] The air flotation platform is used to provide overall support for the system; the air flotation simulator is installed on the air flotation platform and is used to move on the air flotation platform to simulate the on-orbit assembly of components or spacecraft; the flexible simulation part is installed on the air flotation simulator and is used to provide the air flotation simulator with horizontal flexible base damping, and is also used to dock with the robotic arm to achieve equivalence with the large flexible time-varying base under on-orbit conditions; the robotic arm is the core actuating component of the entire experimental system and is used to equivalently replicate the on-orbit movements of the space robotic arm; the hand-eye recognition camera is installed at the end of the robotic arm to identify the target to be grasped by the robotic arm, and can also cooperate with the robotic arm to recognize the posture and position of the grasped target The circumferential motion capture camera is used to monitor and measure the overall test system, and measures the spatial coordinates and posture of the characteristic target ball under the set reference through the form of a camera array, providing a basis for feedback control for the air flotation simulator and the robotic arm; the air supply equipment is used to provide compressed air, and the air model formed separates the air flotation simulator from the air flotation platform, thereby achieving low-resistance movement of the air flotation simulator; the large-tolerance docking joint is installed on the flexible simulation part to verify the docking range of the robotic arm after grasping the component, and the picking and docking capability of the on-orbit assembly robotic arm under different conditions is verified by adjusting the maximum tolerance range of the docking joint.

[0008] The air-floating platform is composed of an air-floating table and a level adjustment device, which is used to provide overall support for the system. The surface of the air-floating table is made of a composite plane composed of cast iron and honeycomb aluminum and is ground. The level adjustment device is located below the air-floating table and is used to adjust the overall flatness and horizontal height of the table.

[0009] There are two air flotation simulators, both of which adopt three degrees of freedom; each air flotation simulator is equipped with an air flotation foot support and a cold air injection device installed laterally.

[0010] The cold air injection device comprises eight-directional injection electromagnetic valves to simulate the on-orbit motion state of a spacecraft with three degrees of freedom, two translations and one rotation, on an air floating platform.

[0011] The large-tolerance docking joint is divided into an active end and a passive end. The active end extends outward and closes by means of claws to capture the passive end, thereby achieving the effect of expanding the tolerance and capture range, which is used to verify the docking range after the robot arm grasps the component; by adjusting the maximum tolerance range of the docking joint, the picking and docking capability of the on-track assembly robot arm under different conditions is verified.

[0012] The flexible simulation component includes a simulation component crossbeam and a simulation component vertical rod; one end of the simulation component vertical rod is fixed on the ground, and the other end is in contact with the air flotation simulator, so as to provide flexible base-like damping in the horizontal direction for the air flotation simulator; the simulation component crossbeam adopts a T-shape, and there are two groups in total. The first group of simulation component crossbeams together with the robotic arm are fixed on one air flotation simulator, and the second group of simulation component crossbeams are fixed on another air flotation simulator; the active end and the passive end of the large-tolerance butt joint are respectively installed on the two groups of simulation component crossbeams, and are moved closer to the other group of simulation component crossbeams with the assistance of the robotic arm, so as to achieve equivalence with a large-flexibility time-varying base under on-orbit conditions.

[0013] The robotic arm adopts a symmetrical distribution of degrees of freedom, and is composed of 7 joints, 1 end effector, 2 arm rods, 1 central controller and a set of end six-dimensional force sensing and measurement system; the configuration of the robotic arm joints adopts a shoulder + elbow + wrist layout, that is, the shoulder swivel joint, shoulder yaw joint, shoulder pitch joint, elbow pitch joint, wrist pitch joint, wrist yaw joint and wrist swivel joint are arranged in sequence from the shoulder to the wrist of the robotic arm, and its end is connected to one end of a group of flexible simulation beams.

[0014] The air supply equipment is used to provide compressed air. The compressed air ejected from the air flotation simulator forms an air film between the air flotation platform and the air flotation simulator, so that the air flotation simulator floats as a whole, and the air flotation simulator is separated from the air flotation platform, thereby realizing the low-resistance movement of the air flotation simulator, which is used to simulate the mechanical environment of on-orbit assembly parts and spacecraft in the vacuum environment of space that is basically not subject to interference torque.

[0015] A method for conducting a ground test of an on-orbit assembly robot based on an air-floating platform using the above system comprises:

[0016] All equipment is turned on and on standby. The air supply equipment starts to supply air to the air flotation foot of the air flotation simulator, forming a high-rigidity air film between the air flotation foot and the air flotation platform. The air film is connected to the atmosphere at the inner and outer boundaries of the air flotation foot. The air flotation simulator is separated from the air flotation platform and floats on the air film.

[0017] The circumferential motion capture camera identifies the pre-set target and provides feedback on the position and posture of the existing air flotation simulator;

[0018] The cold air injection device of the air flotation simulator is started, and the electromagnetic control on the nozzle opens or closes one or several nozzles according to the program control instruction, thereby obtaining the required control force or control torque, realizing attitude control, and making the air flotation simulator enter a predetermined relative position;

[0019] The robot arm obtains its own position information through the feedback of its own encoder and circumferential measurement camera, and obtains the interface information on the crossbeam of the grasping flexible simulation part through the hand-eye recognition camera, and then grasps it; after grasping, the end of the robot arm is locked;

[0020] After the robot arm grabs, a rigid-flexible coupling connection is established on the air flotation simulator, and the grabbed air flotation simulator is dragged closer. The robot arm drags so that the active and passive ends of the large tolerance butt joint are close to each other and enter the predetermined tolerance capture area;

[0021] The active and passive ends of the large tolerance butt joint enter the capture range, are connected to each other and locked, and the test ends.

[0022] The advantages of the present invention compared with the prior art are:

[0023] (1) The present invention changes the traditional docking test method by adopting a flexible simulation part, provides controllable offset force and torque control and flexible base vibration damping in the horizontal direction during the on-track assembly process, effectively simulates the large flexibility time-varying base conditions faced by the robot arm during the on-track assembly condition, and improves the authenticity and credibility of the test system.

[0024] (2) The present invention adopts a combination of a circumferential motion capture camera and a hand-eye recognition camera to provide control feedback information reference for the robotic arm and the air flotation simulator at the same time, thereby reducing the recognition error of a single system and improving the test accuracy.

[0025] (3) The present invention achieves a lightweight design by using a honeycomb aluminum and cast iron composite air flotation platform panel, which is lighter and cheaper than the traditional marble panel, so that the experimental device can meet more site requirements and cost-effective requirements, and has better promotion.

[0026] (4) The present invention achieves flexible and variable verification capabilities by adopting large-tolerance butt joints, which can adapt to the verification of on-orbit assembly robots of different sizes, different configurations, and different control algorithms, making the test device more versatile. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the system composition of the present invention; DETAILED DESCRIPTION

[0028] like Figure 1As shown, the present invention is an on-orbit assembly robot ground test system based on an air flotation platform, comprising an air flotation platform 1, a flexible simulation part, an air flotation simulator 2, a robotic arm 6, a hand-eye recognition camera 7, a circumferential motion capture camera 8, an air supply device 9, and a large tolerance docking joint 5.

[0029] The air flotation platform is used to provide overall support for the system; the air flotation simulator is installed on the air flotation platform and is used to move on the air flotation platform to simulate the on-orbit assembly of components or spacecraft; the flexible simulation part is installed on the air flotation simulator and is used to provide the air flotation simulator with horizontal flexible base damping, and is also used to dock with the robotic arm to achieve equivalence with the large flexible time-varying base under on-orbit conditions; the robotic arm is the core actuating component of the entire experimental system and is used to equivalently replicate the on-orbit movements of the space robotic arm; the hand-eye recognition camera is installed at the end of the robotic arm to identify the target to be grasped by the robotic arm, and can also cooperate with the robotic arm to recognize the posture and position of the grasped target The circumferential motion capture camera is used to monitor and measure the overall test system, and measures the spatial coordinates and posture of the characteristic target ball under the set reference through the form of a camera array, providing a basis for feedback control for the air flotation simulator and the robotic arm; the air supply equipment is used to provide compressed air, and the air model formed separates the air flotation simulator from the air flotation platform, thereby achieving low-resistance movement of the air flotation simulator; the large-tolerance docking joint is installed on the flexible simulation part to verify the docking range of the robotic arm after grasping the component, and the picking and docking capability of the on-orbit assembly robotic arm under different conditions is verified by adjusting the maximum tolerance range of the docking joint.

[0030] The air-floating platform is composed of an air-floating table and a level adjustment device, which is used to provide overall support for the system. The surface of the air-floating table is made of a composite plane composed of cast iron and honeycomb aluminum and is ground. The level adjustment device is located below the air-floating table and is used to adjust the overall flatness and horizontal height of the table.

[0031] There are two air flotation simulators, both of which adopt three degrees of freedom; each air flotation simulator is equipped with an air flotation foot support and a cold air injection device installed laterally.

[0032] The cold air injection device comprises eight-directional injection electromagnetic valves to simulate the on-orbit motion state of a spacecraft with three degrees of freedom, two translations and one rotation, on an air floating platform.

[0033] The large-tolerance docking joint is divided into an active end and a passive end. The active end extends outward and closes by means of claws to capture the passive end, thereby achieving the effect of expanding the tolerance and capture range, which is used to verify the docking range after the robot arm grasps the component; by adjusting the maximum tolerance range of the docking joint, the picking and docking capability of the on-track assembly robot arm under different conditions is verified.

[0034] The flexible simulation component includes a simulation component crossbeam 4 and a simulation component vertical rod 3; one end of the simulation component vertical rod is fixed on the ground, and the other end is in contact with the air flotation simulator, which is used to provide flexible base-like damping in the horizontal direction for the air flotation simulator; the simulation component crossbeam adopts a T-shape, and there are two groups in total. The first group of simulation component crossbeams together with the robotic arm are fixed on one air flotation simulator, and the second group of simulation component crossbeams are fixed on another air flotation simulator; the active end and the passive end of the large-tolerance butt joint are respectively installed on the two groups of simulation component crossbeams, and are moved closer to the other group of simulation component crossbeams with the assistance of the robotic arm, achieving equivalence with a large-flexibility time-varying base under on-orbit conditions.

[0035] The robotic arm adopts a symmetrical distribution of degrees of freedom, and is composed of 7 joints, 1 end effector, 2 arm rods, 1 central controller and a set of end six-dimensional force sensing and measurement system; the configuration of the robotic arm joints adopts a shoulder + elbow + wrist layout, that is, the shoulder swivel joint, shoulder yaw joint, shoulder pitch joint, elbow pitch joint, wrist pitch joint, wrist yaw joint and wrist swivel joint are arranged in sequence from the shoulder to the wrist of the robotic arm, and its end is connected to one end of a group of flexible simulation beams.

[0036] The air supply equipment is used to provide compressed air. The compressed air ejected from the air flotation simulator forms an air film between the air flotation platform and the air flotation simulator, so that the air flotation simulator floats as a whole, and the air flotation simulator is separated from the air flotation platform, thereby realizing the low-resistance movement of the air flotation simulator, which is used to simulate the mechanical environment of on-orbit assembly parts and spacecraft in the vacuum environment of space that is basically not subject to interference torque.

[0037] The present invention also relates to a ground test method of an on-orbit assembly robot based on an air floating platform, which specifically includes the following steps:

[0038] (1) All equipment is turned on and on standby. The air supply equipment starts to supply air to the air foot of the three-degree-of-freedom air flotation simulator, forming a high-rigidity air film between the air foot and the cast iron platform. The air film is connected to the atmosphere at the inner and outer boundaries of the air foot, creating a zero-gravity, frictionless dynamic environment similar to that in space. Both air flotation simulators are separated from the cast iron platform and float on the air film.

[0039] (2) The circumferential motion capture camera identifies the pre-set target and provides feedback on the position and posture of the existing air flotation simulator;

[0040] (3) The cold air injection device of the three-degree-of-freedom air flotation simulator is started and controlled by the electromagnetic control valve on the nozzle. The control valve opens or closes one or several nozzles according to the instructions of the program control device, thereby obtaining the appropriate control force or control torque to achieve attitude control and enable the two air flotation simulators to enter the predetermined relative position.

[0041] (4) The seven-degree-of-freedom robot arm obtains its own position information through the feedback of its own encoder and circumferential measurement camera, and obtains the interface information on the grasping flexible simulation part through the hand-eye recognition camera, and then grasps it. This process verifies the robot arm's ability to pick up parts under the flexible base working condition. After grasping, the end of the robot arm is locked;

[0042] (5) After the robot arm grabs, a rigid-flexible coupling connection is established between the two air-floating simulators, and the grabbed air-floating simulator is dragged close to it. This process verifies the dragging docking capability of the robot arm under the flexible base working condition. The dragging of the robot arm makes the active end and the passive end of the large tolerance docking joint approach each other and enter the predetermined tolerance capture area;

[0043] (6) The active and passive ends of the large tolerance butt joint enter the capture range, connect with each other, and are locked, and the test ends.

[0044] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A ground test system for an on-orbit assembly robot based on an air-floating platform, characterized in that: include: Air flotation platform, air flotation simulator, flexible simulation parts, robotic arms, hand-eye recognition cameras, circumferential motion capture cameras, air supply equipment and large tolerance docking joints; The air-floating platform is used to provide overall support for the system; the air-floating simulator is installed on the air-floating platform and is used to move on the air-floating platform to simulate the on-orbit assembly of components or spacecraft; the flexible simulation part is installed on the air-floating simulator and is used to provide the air-floating simulator with horizontal flexible base damping, and is also used to dock with the robotic arm to achieve equivalence with the large-flexure time-varying base under on-orbit conditions; the robotic arm is the core actuating component of the entire experimental system and is used to equivalently replicate the on-orbit movements of the space robotic arm; the hand-eye recognition camera is installed at the end of the robotic arm and is used to identify the target to be grasped by the robotic arm. At the same time, it can cooperate with the robotic arm to identify the posture and position of the grasped target and provide information feedback to the robotic arm; The circumferential motion capture camera is used to monitor and measure the entire test system. It measures the spatial coordinates and posture of the characteristic target ball under the set reference through a camera array, providing a basis for feedback control for the air flotation simulator and the robotic arm. The air supply equipment is used to provide compressed air. The air model formed separates the air flotation simulator from the air flotation platform, thereby achieving low-resistance movement of the air flotation simulator. The large-tolerance docking joint is installed on the flexible simulation part to verify the docking range after the robotic arm grasps the component. By adjusting the maximum tolerance range of the docking joint, the picking and docking capability of the on-orbit assembly robotic arm under different conditions is verified.

2. The ground test method of an on-orbit assembly robot based on an air-floating platform according to claim 1 is characterized in that: The air-floating platform is composed of an air-floating table and a level adjustment device, which is used to provide overall support for the system. The surface of the air-floating table is made of a composite plane composed of cast iron and honeycomb aluminum and is ground. The level adjustment device is located below the air-floating table and is used to adjust the overall flatness and horizontal height of the table.

3. The ground test method of an on-orbit assembly robot based on an air-floating platform according to claim 1 is characterized in that: There are two air flotation simulators, both of which adopt three degrees of freedom; each air flotation simulator is equipped with an air flotation foot support and a cold air injection device installed laterally.

4. The ground test method of an on-orbit assembly robot based on an air-floating platform according to claim 3 is characterized in that: The cold air injection device comprises eight-directional injection electromagnetic valves to simulate the on-orbit motion state of a spacecraft with three degrees of freedom, two translations and one rotation, on an air floating platform.

5. The ground test method of an on-orbit assembly robot based on an air-floating platform according to claim 3 is characterized in that: The large-tolerance docking joint is divided into an active end and a passive end. The active end extends outward and closes by means of claws to capture the passive end, thereby achieving the effect of expanding the tolerance and capture range, which is used to verify the docking range after the robot arm grasps the component; by adjusting the maximum tolerance range of the docking joint, the picking and docking capability of the on-track assembly robot arm under different conditions is verified.

6. The ground test method of an on-orbit assembly robot based on an air-floating platform according to claim 5 is characterized in that: The flexible simulation component includes a simulation component crossbeam and a simulation component vertical rod; one end of the simulation component vertical rod is fixed on the ground, and the other end is in contact with the air flotation simulator, so as to provide flexible base-like damping in the horizontal direction for the air flotation simulator; the simulation component crossbeam adopts a T-shape, and there are two groups in total. The first group of simulation component crossbeams together with the robotic arm are fixed on one air flotation simulator, and the second group of simulation component crossbeams are fixed on another air flotation simulator; the active end and the passive end of the large-tolerance butt joint are respectively installed on the two groups of simulation component crossbeams, and are moved closer to the other group of simulation component crossbeams with the assistance of the robotic arm, so as to achieve equivalence with a large-flexibility time-varying base under on-orbit conditions.

7. The ground test method of an on-orbit assembly robot based on an air-floating platform according to claim 6 is characterized in that: The robotic arm adopts a symmetrical distribution of degrees of freedom, and is composed of 7 joints, 1 end effector, 2 arm rods, 1 central controller and a set of end six-dimensional force sensing and measurement system; the configuration of the robotic arm joints adopts a shoulder + elbow + wrist layout, that is, the shoulder swivel joint, shoulder yaw joint, shoulder pitch joint, elbow pitch joint, wrist pitch joint, wrist yaw joint and wrist swivel joint are arranged in sequence from the shoulder to the wrist of the robotic arm, and its end is connected to one end of a group of flexible simulation beams.

8. The ground test method of an on-orbit assembly robot based on an air-floating platform according to claim 1 is characterized in that: The air supply equipment is used to provide compressed air. The compressed air ejected from the air flotation simulator forms an air film between the air flotation platform and the air flotation simulator, so that the air flotation simulator floats as a whole, and the air flotation simulator is separated from the air flotation platform, thereby realizing the low-resistance movement of the air flotation simulator, which is used to simulate the mechanical environment of on-orbit assembly parts and spacecraft in the vacuum environment of space that is basically not subject to interference torque.

9. A method for conducting a ground test of an on-orbit assembly robot based on an air-floating platform using the above system, characterized in that: include: All equipment is turned on and on standby. The air supply equipment starts to supply air to the air flotation foot of the air flotation simulator, forming a high-rigidity air film between the air flotation foot and the air flotation platform. The air film is connected to the atmosphere at the inner and outer boundaries of the air flotation foot. The air flotation simulator is separated from the air flotation platform and floats on the air film. The circumferential motion capture camera identifies the pre-set target and provides feedback on the position and posture of the existing air flotation simulator; The cold air injection device of the air flotation simulator is started, and the electromagnetic control on the nozzle opens or closes one or several nozzles according to the program control instruction, thereby obtaining the required control force or control torque, realizing attitude control, and making the air flotation simulator enter a predetermined relative position; The robot arm obtains its own posture information through the feedback of its own encoder and circumferential measurement camera, and obtains the interface information on the crossbeam of the grasping flexible simulation part through the hand-eye recognition camera, and then grasps it; The end of the robot arm is locked after grasping; After the robot arm grabs, a rigid-flexible coupling connection is established on the air flotation simulator, and the grabbed air flotation simulator is dragged closer. The robot arm drags so that the active and passive ends of the large tolerance butt joint are close to each other and enter the predetermined tolerance capture area; The active and passive ends of the large tolerance butt joint enter the capture range, are connected to each other and locked, and the test ends.

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