A microgravity simulation device and method for a satellite antenna

Abstract

The application relates to a micro-gravity simulation device and method of a satellite antenna, belonging to the field of transmission devices. The device comprises a satellite antenna unfolding arm, a satellite antenna, a support frame body, a follow-up mechanical arm, a tension adjusting device, a gravity unloading device and an antenna hanging adjusting device. The follow-up mechanical arm and the satellite antenna unfolding arm are arranged in parallel on the satellite antenna unfolding arm, and one end of the satellite antenna unfolding arm and the follow-up mechanical arm is installed on the support frame body. The satellite antenna unfolding arm is connected with the follow-up mechanical arm through the gravity unloading device and the tension adjusting device. The other end of the satellite antenna unfolding arm is provided with the satellite antenna. The other end of the follow-up mechanical arm is provided with the antenna hanging adjusting device. The antenna hanging adjusting device is connected with the satellite antenna. The application provides a real zero-gravity ground simulation environment for the unfolding characteristic test of the satellite antenna unfolding arm. The application ensures that each hanging rope is in a tensioned state during movement, plays a role of gravity unloading, and has low cost.

Description

Technical Field

[0001] This invention relates to a microgravity simulation device and method for satellite antennas, belonging to the field of transmission devices. Background Technology

[0002] In current aerospace technology, satellites often carry detection radars. The radar servo mechanism provides a support and movement platform for the radar's antenna feed assembly, enabling the radar to search for and track targets. The radar servo mechanism relies on motors to drive its actuators. In space, the satellite is in a weightless state, and the motors only need to provide torque due to inertia to the actuators of the radar servo mechanism, without any gravitational torque. However, in ground-based experiments, due to gravity, the motors need to overcome the additional torque caused by gravity throughout the entire movement of the radar servo mechanism. This gravitational torque is far greater than the torque caused by inertia, becoming the main source of power consumption for the motors. Therefore, eliminating gravity interference is crucial in ground-based experiments of the radar servo mechanism. This necessitates providing a gravity unloading device that allows the radar servo mechanism to operate without the influence of gravitational torque during ground-based experiments, simulating the vacuum and weightlessness environment of space to the greatest extent possible.

[0003] To verify the stability and safety of aerospace equipment on the ground, some researchers have proposed a series of low-gravity environment simulation methods, such as air suspension, drop tower method, and suspension method. Among these, the suspension method for ground-based low-gravity environment simulation is widely used. Suspension-based low-gravity environment simulation devices have lower requirements for the experimental environment, longer experimental time compared to the drop tower method, and are more stable and have higher control precision than the air suspension method. Therefore, they are widely used, mainly in low-gravity experiments involving planetary rovers, robotic arms, and spacecraft. However, in general suspension simulations, the suspension point must move together with the test target. This movement generates follow-up deviations, which cause interference torques in the horizontal direction of the suspension cable, disrupting the mechanical environment of the microgravity simulation.

[0004] Therefore, there is an urgent need to propose a novel microgravity simulation device and method for satellite antennas to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a microgravity simulation device for a space robotic arm suspension system. A horizontal servo control system provides a compensating force in the vertical direction via a constant tension device to counteract the target object's own weight, achieving microgravity simulation in the vertical direction. To provide a realistic zero-gravity ground simulation environment for testing the deployment characteristics of a satellite antenna arm, this invention employs a suspension method to design a satellite antenna gravity unloading device. During deployment, each suspension cable is kept taut throughout the movement, effectively unloading the gravity. The robotic arm providing gravity compensation has the same structure as the antenna deployment arm, is suitable for specific deployment methods, and is relatively low-cost. A brief overview of the invention is provided below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0006] The technical solution of this invention:

[0007] Option 1: A microgravity simulation device for a satellite antenna, comprising a satellite antenna deployment arm, a satellite antenna, a support frame, a follower robotic arm, a tension adjustment device, a gravity unloading device, and an antenna suspension adjustment device. The follower robotic arm and the satellite antenna deployment arm are arranged side-by-side vertically, with one end of each being mounted on the support frame. The satellite antenna deployment arm is connected to the follower robotic arm via the gravity unloading device and the tension adjustment device. The satellite antenna is mounted on the other end of the satellite antenna deployment arm, and the antenna suspension adjustment device is mounted on the other end of the follower robotic arm. The antenna suspension adjustment device is connected to the satellite antenna.

[0008] Preferably, the follower robotic arm includes a drive motor, a first follower arm segment, a second follower arm segment, a follower cylindrical joint, a first follower joint, and a second follower joint. One end of the first follower arm segment is hinged to the support frame via the first follower joint, and a drive motor is connected to the hinge. The output end of the drive motor drives the first follower arm segment to swing. The other end of the first follower arm segment is connected to one end of the second follower arm segment via the follower cylindrical joint. The other end of the second follower arm segment is equipped with an antenna suspension and adjustment device via the second follower joint.

[0009] Preferably, the satellite antenna deployable arm includes a first deployable segment arm, a second deployable segment arm, a deployable cylindrical joint, a first deployable joint, and a second deployable joint. One end of the first deployable segment arm is hinged to the support frame via the first deployable joint, and the other end of the first deployable segment arm is connected to one end of the second follower segment arm via the deployable cylindrical joint. The other end of the second follower segment arm is connected to the satellite antenna via the second deployable joint.

[0010] Preferably, the first follower arm is connected to the first deployable arm via a gravity unloading device, and the second follower arm is connected to the second deployable arm via a tension adjustment device.

[0011] Preferably, the gravity unloading device includes a first slide, a first electric cylinder, a first tension sensor, a first biaxial protractor, a fixed pulley, a first sling, and a second sling. The top of the first electric cylinder is mounted on the first follower arm via the first slide. The bottom of the first electric cylinder is mounted on the fixed pulley via the first sling. The second sling passes through the fixed pulley and is fixedly connected to the first unfolding arm at both ends. The lower end of the first electric cylinder is provided with a first tension sensor and a first biaxial protractor. The first tension sensor measures the tension on the first sling, and the first biaxial protractor measures the vertical tilt angle of the first sling.

[0012] Preferably, the tension adjustment device includes a second slide, an ear joint, a second electric cylinder, a second tension sensor, a second biaxial protractor, and a third sling. The second slide is mounted on the second follower arm. The top end of the second electric cylinder is mounted on the second slide via the ear joint. The two ends of the third sling are fixedly connected to the bottom end of the second electric cylinder and the second unfolding arm, respectively. The lower end of the second electric cylinder is provided with a second tension sensor and a second biaxial protractor. The second tension sensor measures the tension on the third sling, and the second biaxial protractor measures the vertical tilt angle of the third sling.

[0013] Preferably, the antenna suspension and adjustment device includes an X-axis slide, a Y-axis slide, a Z-axis slide, a third electric cylinder, a fourth sling, a ball bearing, a lifting beam, a fifth sling, a third tension sensor, and a third biaxial protractor. The X-axis slide is mounted on the second follower joint, the Y-axis slide is mounted on the X-axis slide, the Z-axis slide is mounted on the Y-axis slide, the top of the third electric cylinder is mounted on the Z-axis slide, and the bottom of the third electric cylinder is connected to the ball bearing via the fourth sling. A lifting beam is mounted on the ball bearing, and both ends of the lifting beam are connected to the satellite antenna via the fifth sling. The lower end of the third electric cylinder is equipped with a third tension sensor and a third biaxial protractor. The third tension sensor measures the tension on the fourth sling, and the third biaxial protractor measures the vertical tilt angle of the fourth sling.

[0014] Option 2, a method for a microgravity simulation device for a satellite antenna, is based on the microgravity simulation device for a satellite antenna described in Option 1, and includes the following steps:

[0015] Step 1: The follow-up robotic arm and the satellite antenna deployment arm swing horizontally: Start the drive motor to make the follow-up robotic arm rotate and unfold. The satellite antenna deployment arm unfolds synchronously with the follow-up robotic arm. Based on the data measured by the first tension sensor, the first dual-axis goniometer, the second tension sensor, and the second dual-axis goniometer, the first slide and the second slide are compensated and finely adjusted respectively to ensure that the center of mass of the satellite antenna does not change in the vertical direction.

[0016] Step 2: The second follower arm and the second deploying arm rotate around the central axis: Set the center of gravity axis of the follower arm as the X-axis, and set the rotation direction of the second follower joint perpendicular to the X-axis as the Y-axis. Start the follower cylindrical joint to make the second follower arm rotate around the X-axis. The range of motion around the X-axis is ±20°. Based on the data measured by the first tension sensor, the first dual-axis goniometer, the second tension sensor, and the second dual-axis goniometer, compensate and adjust the first slide, the first electric cylinder, the second slide, and the second electric cylinder respectively until the tension measured by the second tension sensor above the second deploying arm balances the overall weight of the second deploying arm.

[0017] Step 3: Deploy the antenna suspension adjustment device around the Y-axis: Activate the second deployment joint to deploy the antenna suspension adjustment device around the Y-axis. The range of motion around the Y-axis is ±45°. The tension adjustment device adjusts the extension or retraction length of the second electric cylinder based on the information fed back by the second tension sensor and the second dual-axis protractor, ensuring that the tension provided by the four third slings on the second follower arm can balance the overall weight of the second deployment arm. At the same time, the antenna suspension adjustment device adjusts the X-axis slide, Y-axis slide, and / or Z-axis slide respectively based on the data fed back by the third tension sensor and the third dual-axis protractor, so that the fourth sling passes through the center of mass of the satellite antenna.

[0018] The present invention has the following beneficial effects:

[0019] 1. This invention has a simple structure, is easy to operate and install, and ensures that each sling is taut during the movement, thus achieving the effect of gravity unloading, and has a low cost;

[0020] 2. The follow-up robotic arm of the present invention is the same as the satellite antenna deployment arm, which can realize multi-micro-angle adjustment, and through the adjustment of the tension adjustment device and the gravity unloading device, the follow-up robotic arm can always realize the gravity unloading of the satellite antenna and its deployment arm.

[0021] 3. The present invention has high precision. The tension of each suspension point on the satellite antenna can be adjusted. Furthermore, the fine adjustment of the first slide, the second slide, the X-axis slide, the Y-axis slide, and the Z-axis slide can ensure that the suspension force provided by the sling passes through the center of mass of each component. Attached Figure Description

[0022] Figure 1This is a 3D diagram of a microgravity simulation device for a satellite antenna;

[0023] Figure 2 It is a diagram showing the installation of the satellite antenna deployment arm and the follow-up robotic arm.

[0024] Figure 3 This is a 3D view of the tension adjustment device;

[0025] Figure 4 This is a 3D view of a gravity unloading device;

[0026] Figure 5 This is a 3D view of the antenna suspension and adjustment device;

[0027] Figure 6 This is a simplified force diagram of the servo robotic arm;

[0028] Figure 7 This is a simplified diagram showing the positional relationship between the first deploying segment and the first follower segment;

[0029] In the diagram: 1-Satellite antenna deployment arm; 2-Satellite antenna; 3-Support frame; 4-Follow-up robotic arm; 5-Tension adjustment device; 6-Gravity unloading device; 7-Antenna hanging adjustment device; 11-First deployment segment arm; 12-Second deployment segment arm; 13-Deployment cylindrical joint; 14-First deployment joint; 15-Second deployment joint; 41-Drive motor; 42-First follower segment arm; 43-Second follower segment arm; 44-Follower cylindrical joint; 45-First follower joint; 46-Second follower joint; 51-Second slide; 52-Ear joint. 53-Second electric cylinder, 54-Second tension sensor, 55-Second dual-axis protractor, 56-Third sling, 61-First slide, 62-First electric cylinder, 63-First tension sensor, 64-First dual-axis protractor, 65-Fixed pulley, 66-First sling, 67-Second sling, 71-X-direction slide, 72-Y-direction slide, 73-Z-direction slide, 74-Third electric cylinder, 75-Fourth sling, 76-Spherical bearing, 77-Lifting beam, 78-Fifth sling, 79-Third tension sensor, 710-Third dual-axis protractor. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0031] The connections mentioned in this invention are divided into fixed connections and detachable connections. Fixed connections, also known as non-detachable connections, include but are not limited to conventional fixed connection methods such as folded connections, riveted connections, adhesive connections, and welded connections. Detachable connections include but are not limited to conventional disassembly methods such as threaded connections, snap-fit ​​connections, pin connections, and hinged connections. When a specific connection method is not explicitly defined, it is assumed that at least one existing connection method can always be found to achieve the function, and those skilled in the art can choose according to their needs. For example, a welded connection can be chosen for fixed connections, and a hinged connection can be chosen for detachable connections.

[0032] Specific implementation method one: Combining Figures 1-7 This embodiment describes a microgravity simulation device for a satellite antenna, comprising a satellite antenna deployment arm 1, a satellite antenna 2, a support frame 3, a follower robotic arm 4, a tension adjustment device 5, a gravity unloading device 6, and an antenna suspension adjustment device 7. The follower robotic arm 4 and the satellite antenna deployment arm 1 are arranged side-by-side vertically, with one end of each being mounted on the support frame 3. The satellite antenna deployment arm 1 is connected to the follower robotic arm 4 via the gravity unloading device 6 and the tension adjustment device 5. The satellite antenna 2 is mounted on the other end of the satellite antenna deployment arm 1, and the antenna suspension adjustment device 7 is mounted on the other end of the follower robotic arm 4, with the antenna suspension adjustment device 7 connected to the satellite antenna 2.

[0033] The satellite antenna deployment arm 1 controls the deployment and retraction of the satellite antenna. The support frame 3 provides support for the follow-up robotic arm 4 and the satellite antenna deployment arm 1, ensuring the overall rigidity of the system. The follow-up robotic arm 4 follows the movement of the satellite antenna deployment arm 1, providing a basis for gravity compensation adjustment. The tension adjustment device 5 provides tension to the satellite antenna deployment arm 1 and balances the torque, enabling the follow-up robotic arm 4 to vertically follow the center of mass of the satellite antenna deployment arm 1. The gravity unloading device 6 can adjust the tension of the electric cylinder on the rope in a closed loop based on sensor feedback.

[0034] The servo robotic arm 4 includes a drive motor 41, a first servo arm 42, a second servo arm 43, a servo cylindrical joint 44, a first servo joint 45, and a second servo joint 46. One end of the first servo arm 42 is hinged to the support frame 3 through the first servo joint 45, and the drive motor 41 is connected to the hinge. The output end of the drive motor 41 drives the first servo arm 42 to swing. The other end of the first servo arm 42 is connected to one end of the second servo arm 43 through the servo cylindrical joint 44. The other end of the second servo arm 43 is equipped with an antenna suspension and adjustment device 7 through the second servo joint 46.

[0035] The servo robotic arm 4 can move synchronously with the satellite antenna deployment arm 1, and the tension adjustment device 5 and gravity unloading device 6 fixedly connected to it provide a basis for gravity compensation adjustment.

[0036] The satellite antenna deployable arm 1 includes a first deployable segment arm 11, a second deployable segment arm 12, a deployable cylindrical joint 13, a first deployable joint 14, and a second deployable joint 15. One end of the first deployable segment arm 11 is hinged to the support frame 3 through the first deployable joint 14, and the other end of the first deployable segment arm 11 is connected to one end of the second follower segment arm 43 through the deployable cylindrical joint 13. The other end of the second follower segment arm 43 is connected to the satellite antenna 2 through the second deployable joint 15.

[0037] The first follower arm 42 is connected to the first deployable arm 11 through the gravity unloading device 6, and the second follower arm 43 is connected to the second deployable arm 12 through the tension adjustment device 5.

[0038] The gravity unloading device 6 includes a first slide 61, a first electric cylinder 62, a first tension sensor 63, a first biaxial protractor 64, a fixed pulley 65, a first sling 66, and a second sling 67. The top of the first electric cylinder 62 is bolted to the first follower arm 42 via the first slide 61. The bottom of the first electric cylinder 62 is fitted with a fixed pulley 65 via the first sling 66. The second sling 67 passes through the fixed pulley 65 and is fixedly connected to the first unfolding arm 11 at both ends. The lower end of the first electric cylinder 62 is provided with a first tension sensor 63 and a first biaxial protractor 64. The first tension sensor 63 measures the tension on the first sling 66, and the first biaxial protractor 64 measures the vertical tilt angle of the first sling 66.

[0039] The first electric cylinder 62 can follow the movement of the slider on the first slide table 61 to adjust the center of gravity of the suspension. The first tension sensor 63 and the first dual-axis protractor 64 connected to the lower end of the first electric cylinder 62 respectively provide feedback on the tension change on the first sling 66 and the vertical tilt angle of the first sling 66, providing feedback information to the follow-up robotic arm 4 and the first slide table 61, so that the center position can be adjusted at any time to keep it consistent with the center of gravity of the satellite antenna deployment arm 1 in the vertical direction. The second sling 67 is connected to the rope clamp installed on the lower end of the satellite antenna deployment arm 1, and the tension always passes through the center of gravity of the antenna and the various components of the satellite antenna deployment arm 1. The fixed pulley 65 can extend the single second sling 67 into two, which are respectively used to suspend the first and last ends of the satellite antenna deployment arm 1, balancing the torque and ensuring that when the deployment arm of the satellite antenna 2 swings in the horizontal direction, the follow-up robotic arm 4 can vertically follow the center of gravity of the satellite antenna deployment arm 1. During the deployment process, the first electric cylinder 62 adjusts the extension and retraction of the push rod according to the tension of the first sling 66, thereby achieving high-precision tension control.

[0040] The tension adjustment device 5 includes a second slide 51, an ear joint 52, a second electric cylinder 53, a second tension sensor 54, a second biaxial protractor 55, and a third sling 56. The second slide 51 is mounted on the second follower arm 43. The top of the second electric cylinder 53 is mounted on the second slide 51 through the ear joint 52. There are two ear joints 52, and two second electric cylinders 53 are installed under each ear joint 52. The two ends of the third sling 56 are fixedly connected to the bottom end of the second electric cylinder 53 and the second unfolding arm 12, respectively. The lower end of the second electric cylinder 53 is provided with a second tension sensor 54 and a second biaxial protractor 55. The second tension sensor 54 measures the tension on the third sling 56, and the second biaxial protractor 55 measures the vertical tilt angle of the third sling 56.

[0041] When the follower cylindrical joint 44 rotates, the second electric cylinder 53 remains vertically downward. The extension or retraction of the second electric cylinder 53 adjusts the center of gravity of the suspension, preventing off-center loading due to the rotation of the follower cylindrical joint 44. Feedback from the second tension sensor 54 and the second biaxial protractor 55 controls the extension and retraction of the second electric cylinder 53, maintaining a constant tension output and appropriately adjusting the length of the third sling 56 to achieve vertical following. A movable rope clamp is installed on the satellite antenna deployment arm 1, allowing adjustment of the suspension direction of the third sling 56 to ensure that the tension always passes through the center of gravity of the satellite antenna 2 and all components of the satellite antenna deployment arm 1.

[0042] The antenna suspension and adjustment device 7 includes an X-axis slide 71, a Y-axis slide 72, a Z-axis slide 73, a third electric cylinder 74, a fourth sling 75, a ball bearing 76, a lifting beam 77, a fifth sling 78, a third tension sensor 79, and a third dual-axis goniometer 710. The X-axis slide 71 is mounted on the second follower joint 46. The Y-axis slide 72 is mounted on the X-axis slide 71, and the Z-axis slide 73 is mounted on the Y-axis slide 72. The top of the third electric cylinder 74 is mounted on the Z-axis slide 73. On the slide table 73, the bottom end of the third electric cylinder 74 is connected to the ball bearing 76 via the fourth sling 75. A lifting beam 77 is installed on the ball bearing 76. Both ends of the lifting beam 77 are connected to the satellite antenna 2 via the fifth sling 78. The lower end of the third electric cylinder 74 is equipped with a third tension sensor 79 and a third biaxial goniometer 710. The third tension sensor 79 measures the tension on the fourth sling 75, and the third biaxial goniometer 710 measures the vertical tilt angle of the fourth sling 75.

[0043] The third electric cylinder 74 adjusts the tension on the fifth sling 78 by extending or retracting; the third tension sensor 79 forms a feedback loop for the electric cylinder adjustment; the X-axis slide 71, Y-axis slide 72, and Z-axis slide 73 can fine-tune the position of the fifth sling 78 based on the information fed back by the third dual-axis protractor 710, ensuring it vertically follows the center of mass of the connecting rod. The ball bearing 76 is connected to the fifth sling 78 via the lifting beam 77. By adjusting the position of the lifting point of the fifth sling 78, the fifth sling 78 passes through the center of mass of the satellite antenna 2. The position of the lifting point can be adjusted in the x, y, and z directions via the 3D guide grooves of the X-axis slide 71, Y-axis slide 72, and Z-axis slide 73, and the ball bearing 76 used at the lifting point ensures that the fifth sling 78 always passes through the satellite antenna 2 and its center of mass, thus preventing the generation of additional torque. The third tension sensor 79 and the third dual-axis goniometer 710 are used to enable the robotic arm to follow the movement, so that the fifth sling 78 follows the center of mass of the satellite antenna deployment arm 1 in the horizontal direction, ensuring that the sling is vertical during the gravity unloading process of each component in the satellite antenna deployment arm 1.

[0044] There are four second electric cylinders 53, four second tension sensors 54, four second biaxial goniometers 55 and four third slings 56. There are two second slides 51 and two ear joints 52. Two second electric cylinders 53 are installed on each ear joint 52. A second tension sensor 54, a second biaxial goniometer 55 and a third sling 56 are set below each second electric cylinder 53. That is, the second deployable arm 12 is provided with four lifting points through four third slings 56.

[0045] The follower cylindrical joint 44 is an electric rotary joint with a built-in rotary motor that drives the second follower arm 43 to rotate around the axis.

[0046] Similarly, the second follower joint 46 is an electric hinge joint or an electric swing joint, which has a built-in rotary motor to drive the antenna suspension adjustment device 7 to swing around the hinge axis.

[0047] Specific Implementation Method Two: Combining Figures 1-4 This embodiment describes a microgravity simulation method for a satellite antenna, which is based on the microgravity simulation device for a satellite antenna described in Specific Embodiment 1. In the initial working condition, both the follower robotic arm 14 and the satellite antenna deployment arm 1 are in a tightened state and close to the support frame 3. At this time, the satellite antenna 2 is parallel to the front plane of the support frame 3. The spring suspension cable is kept taut by the electric cylinder adjustment based on information from the tension sensor and the dual-axis protractor, ensuring that the tension provided by the follower robotic arm 4 can balance the gravity acting on the various components of the satellite antenna deployment arm 1 and the satellite antenna 2. The microgravity simulation method for a satellite antenna in this embodiment specifically includes the following steps:

[0048] Step 1: The follow-up robotic arm 4 and the satellite antenna deployment arm 1 swing horizontally: Start the drive motor 41 to make the follow-up robotic arm 4 rotate and unfold. The satellite antenna deployment arm 1 unfolds synchronously with the follow-up robotic arm 4. Based on the data measured by the first tension sensor 63, the first dual-axis goniometer 64, the second tension sensor 54 and the second dual-axis goniometer 55, the first slide 61 and the second slide 51 are compensated and finely adjusted respectively to ensure that the center of mass of the satellite antenna 2 does not change in the vertical direction.

[0049] The drive motor 41 is started, and the drive motor 41 provides power to make the first follower arm 42 rotate and unfold around the first follower joint 45. The range of motion of the first follower joint 45 is 180°. The second follower arm 43 swings accordingly. At the same time, under the action of the gravity unloading device 6 and the tension adjustment device 5, the first unfolding arm 11 and the second unfolding arm 12 unfold synchronously.

[0050] Step 2: The second follower arm 43 and the second deploying arm 12 rotate around the central axis: Set the center of gravity axis of the follower robotic arm 4 as the X-axis, and set the rotation direction of the second follower joint 46 perpendicular to the X-axis as the Y-axis. Start the follower cylindrical joint 44 to make the second follower arm 43 rotate around the X-axis. The range of motion around the X-axis is ±20°. According to the data measured by the first tension sensor 63, the first dual-axis goniometer 64, the second tension sensor 54 and the second dual-axis goniometer 55, the first slide 61, the first electric cylinder 62, the second slide 51 and the second electric cylinder 53 are compensated and adjusted respectively until the tension on the third sling 56 measured by the second tension sensor 54 above the second deploying arm 12 balances the overall weight of the second deploying arm 12.

[0051] When the second follower arm 43 rotates around the X-axis, the four lifting points on the second unfolding arm 12 simultaneously experience displacement in both the X-axis and Y-axis directions. Compensation and fine-tuning solely through centerline arrangement is insufficient to compensate for the eccentric torque. Therefore, the first slide 61 and the second slide 51 need to move a significant distance. Furthermore, the tension adjustment device 5 continuously adjusts the extension or retraction length of the second electric cylinder 53 based on feedback from the second tension sensor 54 and the second dual-axis protractor 55. This ensures that the tension provided by the four third slings 56 on the second follower arm 43 can balance the overall weight of the unfolding second unfolding arm 12.

[0052] Step 3: Antenna Suspension Adjustment Device 7 Deploys Around the Y-Axis: Activate the second deployment joint 15 to deploy the antenna suspension adjustment device 7 around the Y-axis. The range of motion around the Y-axis is ±45°. Then, the antenna suspension adjustment device 7 performs compensation and correction based on the data measured by the third tension sensor 79 and the third dual-axis goniometer 710. That is, the tension adjustment device 5 adjusts the extension or retraction length of the second electric cylinder 53 at all times based on the information fed back by the second tension sensor 54 and the second dual-axis goniometer 55, ensuring that the second follower arm 43... The tension provided by the four third slings 56 can balance the overall weight of the second deployment arm 12. At the same time, the antenna suspension adjustment device 7 adjusts the X-axis slide 71, Y-axis slide 72 and / or Z-axis slide 73 respectively according to the data fed back by the third tension sensor 79 and the third dual-axis protractor 710, thereby adjusting the position of the suspension points provided by the four third slings 56 on the second follower arm 43. Since the suspension beam 77 is connected to the fourth sling 75 through the ball bearing 76, the fourth sling 75 passes through the center of mass of the satellite antenna 2.

[0053] The Z-axis is defined as the direction of movement of the Z-axis slide 73, and the Z-axis is perpendicular to the X-axis and Y-axis.

[0054] The compensation fine-tuning described in step one, the compensation adjustment described in step two, and the compensation correction described in step three are all achieved through an active sling adjustment method. This active sling adjustment method includes the following steps:

[0055] Step a, Angle Change Detection and Adjustment: When the sling angle deviates, the angle sensor identifies the signal. The angle sensor uses the deviation angle as the input signal and drives the first slide 61 and the second slide 51 to move through the sling angle control system, so that the satellite antenna unfolding arm 1 follows, thereby reducing the angle correction sling and keeping it in the vertical direction.

[0056] Step b, tension change detection and adjustment: When the tension of the sling changes, the signal is identified by the tension sensor. The tension sensor takes the sling tension and the initial tension as input signals. Through the sling tension control system, the electric cylinder is driven to change the sling tension, reduce the error value between the sling tension and the initial tension, so that the tension returns to a state equal to the weight of the satellite antenna 2.

[0057] An active sling adjustment method achieves gravity unloading by detecting and controlling changes in tension and angle, which can improve the accuracy of gravity unloading compared with the passive sling counterweight method.

[0058] The sling is a first sling 66, a third sling 56, or a fourth sling 75; the angle sensor is a first biaxial goniometer 64, a second biaxial goniometer 55, or a third biaxial goniometer 710; the tension sensor is a first tension sensor 63, a second tension sensor 54, or a third tension sensor 79; and the electric cylinder is a first electric cylinder 62, a second electric cylinder 53, or a third electric cylinder 74.

[0059] The following are the follow-up tracking steps for the satellite antenna deployable arm 1:

[0060] Step 1: After the system is started, the detection system begins to work, measuring the deviation angle of the sling in the X and Y axis directions using an angle sensor.

[0061] Step 2: When the satellite antenna deployable arm 1 moves, causing the vertical state of the sling to change, i.e., tilting, the tilt angle is detected by the rotary encoder of the angle sensor, the data is recorded and fed back to the main control system.

[0062] Step 3: Install absolute encoders on the first follower joint 45 and the second follower joint 46 to perform position closed loop and ensure the accuracy of joint movement. Use numerical methods to solve the real-time nonlinear relationship between the follower robotic arm 4 and the satellite antenna deployment arm 1. Then, use an active sling adjustment method to ensure that the sling follows the follower robotic arm 4 in the vertical direction, so that it can always maintain synchronous movement with the satellite antenna deployment arm 1 and avoid introducing additional horizontal force.

[0063] Step 4: When the follow-up robotic arm 4 moves the gravity unloading device 6 and the tension adjustment device 5, if the movement exceeds the working space or the tension exceeds the threshold, a signal is immediately sent to stop the movement.

[0064] The main control system includes a host PC system, a slave computer, motor servo drivers, and the controlled object. Based on the angle deviation measured by the dual-axis goniometer on the servo-arm 4, the required displacement of the X-axis and Z-axis slides is calculated. The slave computer generates two corresponding PWM signals based on the received parameters and sends them to the servo drivers. The servo drivers generate two corresponding voltages and apply them to the actuator motors of the X-axis and Z-axis slides respectively. The motors drive their respective loads under their respective voltages. Simultaneously, the dual-axis goniometer feeds back the position to the PC system, completing the closed-loop excavation of the entire system. The gravity compensation system is similar to the servo-arm mechanism. Based on the tension of the sling measured by the force sensor, the required stroke of the electric cylinder is calculated. The servo driver generates a voltage corresponding to the parameters and applies it to the electric cylinder motor. The electric cylinder executes the corresponding stroke. Simultaneously, the force sensor signal is fed back to the main control system through the AD interface, realizing closed-loop force control.

[0065] Figure 6The following is a simplified force diagram of the follower robotic arm 4. The follower robotic arm 4 has three rotational joints, namely the follower cylindrical joint 44, the first follower joint 45, and the second follower joint 46. Therefore, the follower robotic arm 4 follows the satellite antenna deployment arm 1 by controlling the rotation angles θ1, θ2, and θ3 of the three rotational joints of the follower robotic arm. When the rotation angles θ1, θ2, and θ3 of the follower robotic arm 4 and the satellite antenna deployment arm 1 are the same, the position following system follows the position of the satellite antenna deployment arm 1.

[0066] To achieve high-precision position tracking of the satellite antenna deployment arm 1, this embodiment employs admittance control on the follower cylindrical joint 44 and the second follower joint 46 of the follower robotic arm based on the forces acting on the lifting point D and the equivalent lifting point E, and position control on the first follower joint 45 based on spatial geometry. The tension control of the sling is achieved by adjusting the extension and retraction of the electric cylinder in real time based on feedback values ​​from the force sensor; the vertical component of the sling tension counteracts the weight of the suspended load.

[0067] Furthermore, the second follower joint 46 employs the following admittance control method:

[0068] The transformation matrix of the coordinate system of the end effector D point of the servo manipulator relative to the coordinate system of the first joint of the servo manipulator is as follows:

[0069]

[0070] in,

[0071]

[0072] Wherein, the trigonometric functions sin and cos are abbreviated as s and c, and the vector n = (n x ,n y ,n z ) T Let n be the normal vector of the D-point coordinate system. x n x n x Let be the components along the x, y, and z axes, respectively; o, a, and p be the tangent vector, binormal vector, and position vector of the D-point coordinate system, respectively; α and β be the measurements from the angle encoder; and γ be the angle between the sling and the vertical direction. Let be the coordinate transformation matrix from coordinate system i-1 to coordinate system i.

[0073] To ensure that the vertical component of the sling tension at point D can balance the weight of the suspended antenna extension arm components, the expected tension value of the sling at point D of the servo robotic arm is:

[0074] F d3 =G3 / a z3 =G3 / [cβ(cα·cθ)] x-sα·sθ x ·sθ y )-cθ y ·sβ·sθ x ]

[0075] Among them, a 33 =cosγ3 is the cosine of the angle between the sling and the direction of the gravitational field, and G3 is the weight of the antenna deployment arm assembly balanced at sling point D. Therefore, the forces acting on the servo manipulator at sling point D are:

[0076] F3 = [F d3 n x3 F d3 n y3 F d3 n z3 000] T

[0077] The weight of the antenna and some components of the antenna deployment arm balanced at point D of the servo robotic arm is:

[0078]

[0079] At this time, the motor of the second follower joint 46 is operating in position mode, and the torque on the motor shaft of the second follower joint 46 caused by the tension of the sling after gravity compensation at the suspension point D is:

[0080]

[0081] in, Let be the Jacobian vector from the attachment point D of the servo manipulator to the second servo joint 46. To achieve position following of the second servo joint 46 to the second deployment joint 15, an admittance control algorithm is used to design the force following algorithm for the motor shaft of the second servo joint 46:

[0082]

[0083] but

[0084]

[0085] in,

[0086]

[0087] Let be the angle difference of the motor of the second follower joint 46 in the i-th cycle. b3 and k3 are the damping coefficient and stiffness coefficient of the admittance controller of the second follower joint 46, respectively. By adjusting the values ​​of parameters b3 and k3, the sensitivity adjustment of the dynamic relationship between the position of the second follower joint 46 and the force at the lifting point D can be achieved.

[0088] The control method for the aforementioned follower cylindrical joint 44 using admittance control is as follows:

[0089] Unlike the D-point of the robotic arm, the second joint requires at least two lifting points to achieve the centroid offset due to orientational rotation. Considering the uncertainty of the centroid position, this design uses four lifting points B, B', C, and C' for adjustment. These four lifting points have two mutually perpendicular axes of symmetry on the horizontal plane of the centroid, which can be equivalent to the centroid lifting point E. The transformation matrix of the coordinate system of the robotic arm's E-point relative to the coordinate system of the first joint of the robotic arm is:

[0090]

[0091] To ensure that the rope tension at the equivalent E hanging point can balance the gravity in the vertical direction, the vector n2 = (n x2 ,n y2 ,n z2 ) T Let n be the normal vector of the D-point coordinate system. x2 n y2 n z2 Let be the components along the x, y, and z axes, respectively. Let o2, a2, and p2 be the tangent vector, binormal vector, and position vector of the D suspension point coordinate system, respectively. The expected tension of the rope at the equivalent E suspension point of the servo manipulator is:

[0092] F d2 =G2 / a 22 =G2 / (cβ2·cα2·cθ) x -sβ2·sθ x )

[0093] G2 is the gravity value of the antenna deployment arm component balanced at the equivalent E-suspension point, and α2 and β2 are the measurements of the second dual-axis goniometer 55. Therefore, the forces acting on the servo robotic arm at the equivalent E-suspension point are:

[0094] F2 = [F d2 n x2 F d2 n y2 F d2 n z2 000] T

[0095] The weight of the corresponding antenna deployment arm component balanced at the equivalent E-point of the servo robotic arm is:

[0096] F g2 =[00G2000] T

[0097] The motor of the second joint of the servo robotic arm operates in position mode. The torque on the motor shaft of the second joint, caused by the tension of the sling after gravity compensation at equivalent suspension points E and D, is:

[0098]

[0099] in, 2 J E and 2 J D These are the Jacobian vectors from the equivalent attachment points E and D of the servo manipulator to the second joint of the manipulator, respectively.

[0100] To achieve position tracking of the second joint of the servo robotic arm to the second joint of the antenna deployment arm, the control algorithm for the motor shaft of the second joint is designed using admittance control:

[0101]

[0102] but:

[0103]

[0104] Here, b2 and k2 are two parameters of the admittance controller of the second joint of the servo manipulator.

[0105] Finally, the first follower joint 45 employs the following admittance control method:

[0106] The first joint of the servo robotic arm uses position control. Figure 7 A simplified diagram showing the positional relationship between link A of the servo robotic arm and link A of the antenna deployment arm:

[0107] Where α1 and β1 are the measured values ​​of the second biaxial goniometer 64, and γ1 is the angle between the sling and the vertical direction, derived from geometric relationships:

[0108] cosγ1=cosα1·cosβ1

[0109]

[0110] Where θ1 is the relative angle to be executed by the motor shaft of the first joint of the servo manipulator. The desired tension of the sling at the attachment point A of the servo manipulator is:

[0111] F d1 =G1 / cosγ1=G1 / cosα1·cosβ1

[0112] G1 represents the weight of the antenna deployment arm component balanced at attachment point A. In actual experiments, the following error of the servo robotic arm's four links to link A of the satellite antenna deployment arm is very small; therefore, in the actual project, the tension of the sling is always set to the weight of link A.

[0113] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A microgravity simulation method for a satellite antenna is based on a microgravity simulation device for a satellite antenna. The microgravity simulation device for a satellite antenna includes a satellite antenna deployment arm (1), a satellite antenna (2), a support frame (3), a follower robotic arm (4), a tension adjustment device (5), a gravity unloading device (6), and an antenna hanging adjustment device (7). The follower robotic arm (4) and the satellite antenna deployment arm (1) are arranged side by side and aligned. One end of the satellite antenna deployment arm (1) and the follower robotic arm (4) are both installed on the support frame (3). The satellite antenna deployment arm (1) is connected to the follower robotic arm (4) through the gravity unloading device (6) and the tension adjustment device (5). The satellite antenna (2) is installed at the other end of the satellite antenna deployment arm (1). The antenna hanging adjustment device (7) is installed at the other end of the follower robotic arm (4). The antenna hanging adjustment device (7) is connected to the satellite antenna (2). The servo robotic arm (4) includes a drive motor (41), a first servo arm (42), a second servo arm (43), a servo cylindrical joint (44), a first servo joint (45), and a second servo joint (46). One end of the first servo arm (42) is hinged to the support frame (3) through the first servo joint (45), and the drive motor (41) is connected at the hinge. The output end of the drive motor (41) drives the first servo arm (42) to swing. The other end of the first servo arm (42) is connected to one end of the second servo arm (43) through the servo cylindrical joint (44). The other end of the second servo arm (43) is equipped with an antenna hanging adjustment device (7) through the second servo joint (46). The gravity unloading device (6) includes a first slide (61), a first electric cylinder (62), a first tension sensor (63), a first biaxial protractor (64), a fixed pulley (65), a first sling (66), and a second sling (67). The top of the first electric cylinder (62) is mounted on the first follower arm (42) via the first slide (61). The bottom of the first electric cylinder (62) is mounted on the fixed pulley (65) via the first sling (66). The second sling (67) passes through the fixed pulley (65) and is fixedly connected to the first unfolding arm (11) at both ends. The lower end of the first electric cylinder (62) is provided with a first tension sensor (63) and a first biaxial protractor (64). The first tension sensor (63) measures the tension on the first sling (66), and the first biaxial protractor (64) measures the vertical tilt angle of the first sling (66). The satellite antenna deployable arm (1) includes a first deployable arm (11), a second deployable arm (12), a deployable cylindrical joint (13), a first deployable joint (14), and a second deployable joint (15). One end of the first deployable arm (11) is hinged to the support frame (3) through the first deployable joint (14), and the other end of the first deployable arm (11) is connected to one end of the second follower arm (43) through the deployable cylindrical joint (13). The other end of the second follower arm (43) is connected to the satellite antenna (2) through the second deployable joint (15). The microgravity simulation method for a satellite antenna includes the following steps: Step 1: The follower robotic arm (4) and the satellite antenna unfolding arm (1) swing horizontally: Start the drive motor (41) to make the follower robotic arm (4) rotate and unfold. The satellite antenna unfolding arm (1) unfolds synchronously with the follower robotic arm (4). Based on the data measured by the first tension sensor (63), the first dual-axis goniometer (64), the second tension sensor (54), and the second dual-axis goniometer (55), the first slide (61) and the second slide (51) are compensated and finely adjusted respectively so that the center of mass of the satellite antenna (2) does not change in the vertical direction. Step 2: The second follower arm (43) and the second unfolding arm (12) rotate around the central axis: The center of gravity axis of the follower robotic arm (4) is set as the X-axis, and the rotation direction of the second follower joint (46) perpendicular to the X-axis is set as the Y-axis. The follower cylindrical joint (44) is started, so that the second follower arm (43) rotates around the X-axis. The range of motion around the X-axis is ±20°. According to the data measured by the first tension sensor (63), the first dual-axis goniometer (64), the second tension sensor (54), and the second dual-axis goniometer (55), the first slide (61), the first electric cylinder (62), the second slide (51), and the second electric cylinder (53) are compensated and adjusted respectively until the second tension sensor (54) above the second unfolding arm (12) measures the tension on the third sling (56) to balance the overall weight of the second unfolding arm (12). Step 3: Antenna suspension adjustment device (7) unfolds around the Y-axis: Activate the second unfolding joint (15) to unfold the antenna suspension adjustment device (7) around the Y-axis. The range of motion around the Y-axis is ±45°. The tension adjustment device (5) adjusts the extension or retraction length of the second electric cylinder (53) according to the information fed back by the second tension sensor (54) and the second dual-axis protractor (55) to ensure that the tension provided by the four third slings (56) on the second follower arm (43) can balance the overall weight of the unfolding second unfolding arm (12). At the same time, the antenna suspension adjustment device (7) adjusts the X-axis slide (71), Y-axis slide (72), and Z-axis slide (73) respectively according to the data fed back by the third tension sensor (79) and the third dual-axis protractor (710) so that the fourth sling (75) passes through the center of mass of the satellite antenna (2). The compensation fine-tuning described in step one, the compensation adjustment described in step two, and the compensation correction described in step three are all achieved through an active sling adjustment method. This active sling adjustment method includes the following steps: Step a, Angle change detection and adjustment: When the angle of the sling deviates, the angle sensor identifies the signal. The angle sensor takes the deviation angle as the input signal and drives the first slide (61) and the second slide (51) to move through the sling angle control system, so that the satellite antenna unfolding arm (1) follows, thereby reducing the angle correction sling and keeping it in the vertical direction. Step b, tension change detection and adjustment: When the tension of the sling changes, the signal is identified by the tension sensor. The tension sensor takes the tension of the sling and the initial tension as input signals. Through the sling tension control system, the electric cylinder is driven to change the tension of the sling, reduce the error value between the tension of the sling and the initial tension, so that the tension returns to the state equal to the gravity of the satellite antenna (2); The sling is a first sling (66), a third sling (56), or a fourth sling (75); the angle sensor is a first biaxial goniometer (64), a second biaxial goniometer (55), or a third biaxial goniometer (710); the tension sensor is a first tension sensor (63), a second tension sensor (54), or a third tension sensor (79); and the electric cylinder is a first electric cylinder (62), a second electric cylinder (53), or a third electric cylinder (74). The following are the follow-up tracking steps for the satellite antenna deployable arm (1): Step 1: After the system is started, the detection system begins to work, measuring the deviation angle of the sling in the X and Y axis directions using an angle sensor; Step 2: When the satellite antenna unfolding arm (1) moves, causing the vertical state of the sling to change, i.e., tilting occurs, the tilt angle is detected by the rotary encoder of the angle sensor, the data is recorded and fed back to the main control system. Step 3: Install absolute encoders on the first follower joint (45) and the second follower joint (46) to perform position closed loop and ensure the accuracy of joint movement. Use numerical methods to solve the real-time nonlinear relationship between the follower robotic arm (4) and the satellite antenna deployment arm (1). Then, use an active sling adjustment method to ensure that the sling follows the follower robotic arm (4) in the vertical direction, so that it can always maintain synchronous movement with the satellite antenna deployment arm (1) and avoid introducing additional horizontal force. Step 4: When the follow-up robotic arm 4 drives the gravity unloading device (6) and the tension adjustment device (5) to move, if the movement exceeds the working space or the tension exceeds the threshold, a signal is immediately issued to stop the movement.

2. The microgravity simulation method for a satellite antenna according to claim 1, characterized in that: The first follower arm (42) is connected to the first deployable arm (11) through the gravity unloading device (6), and the second follower arm (43) is connected to the second deployable arm (12) through the tension adjustment device (5).

3. The microgravity simulation method for a satellite antenna according to claim 2, characterized in that: The tension adjustment device (5) includes a second slide (51), an ear joint (52), a second electric cylinder (53), a second tension sensor (54), a second biaxial protractor (55), and a third sling (56). The second slide (51) is mounted on the second follower arm (43). The top of the second electric cylinder (53) is mounted on the second slide (51) through the ear joint (52). The two ends of the third sling (56) are fixedly connected to the bottom of the second electric cylinder (53) and the second unfolding arm (12), respectively. The lower end of the second electric cylinder (53) is provided with a second tension sensor (54) and a second biaxial protractor (55). The second tension sensor (54) measures the tension on the third sling (56), and the second biaxial protractor (55) measures the vertical tilt angle of the third sling (56).

4. The microgravity simulation method for a satellite antenna according to claim 3, characterized in that: The antenna suspension adjustment device (7) includes an X-axis slide (71), a Y-axis slide (72), a Z-axis slide (73), a third electric cylinder (74), a fourth sling (75), a ball bearing (76), a suspension beam (77), a fifth sling (78), a third tension sensor (79), and a third dual-axis goniometer (710). The X-axis slide (71) is mounted on the second follower joint (46), the Y-axis slide (72) is mounted on the X-axis slide (71), and the Z-axis slide (73) is mounted on the Y-axis slide (72). The top of the third electric cylinder (74) is equipped with... On the Z-axis slide (73), the bottom end of the third electric cylinder (74) is connected to the ball bearing (76) via the fourth sling (75). A lifting beam (77) is installed on the ball bearing (76). Both ends of the lifting beam (77) are connected to the satellite antenna (2) via the fifth sling (78). The lower end of the third electric cylinder (74) is equipped with a third tension sensor (79) and a third biaxial protractor (710). The third tension sensor (79) measures the tension on the fourth sling (75), and the third biaxial protractor (710) measures the vertical tilt angle of the fourth sling (75).

Images