Active gravity unloading method for flexible lander ground test

Abstract

The application discloses a flexible attached probe ground test active gravity unloading method, and belongs to the technical field of extraterrestrial exploration.The application realizes the method as follows: a flexible attached probe structure is constructed.The flexible attached probe comprises a body bearing plate, a buffer cylinder, a buffer support rigid body structure, and a flexible connecting structure.Motors are respectively connected with the mass center of the flexible rod and the mass center of the node, and the force required by each motor is determined according to a static balance equation.A flexible attached probe gravity unloading ground test system is established.The test system comprises a supporting device, a moving device and a control system.The force generated by the motor is transmitted to the gravity acting on the flexible attached probe through a suspension rope, a motor and a pulley set to complete the quantitative and accurate gravity unloading of the flexible attached probe ground test, and the real simulation of the dynamic characteristics of the flexible attached structure is realized.The application can realize low-frequency motion within a limited range and compensate for large deformation of the structure through multi-node gravity unloading.

Description

TECHNICAL FIELD

[0001] The present application relates to a flexible attachment probe ground test active gravity unloading method, and belongs to the technical field of extraterrestrial exploration. TECHNICAL BACKGROUND

[0002] In recent years, small celestial body attachment and sampling return missions have great scientific significance and engineering value, and have become a research hotspot. Small celestial bodies have light mass and weak gravity, and are prone to rebound during the attachment process, leading to mission failure. In order to actively adapt to a larger attachment speed and avoid probe rebound, a flexible attachment probe with small damping, large flexibility and deformable energy absorption characteristics needs to be designed. In the weak gravity field environment of space attachment, the flexible structure is easily deformed and vibrated under the action of disturbances such as thrust, which greatly affects the control stability and precision, so the simulation of the flexible characteristics of the probe under the weak gravity environment needs to be realized in the ground test verification. At present, the commonly used gravity unloading methods in the laboratory include air floating method, magnetic suspension method and suspension method, etc. The air floating method and the magnetic suspension method are difficult to meet the requirement of large deformation of the structure; and the balloon suspension method is difficult to realize multi-node constant force unloading. The flexible attachment probe has low frequency and large static deformation, and the gravity unloading device is required to realize low-frequency motion in a limited range and to compensate for large deformation of the structure. Based on this, a flexible attachment probe ground test active gravity unloading method is proposed. SUMMARY

[0003] In order to solve the problem of simulating the flexible characteristics of the probe under the weak gravity environment, the purpose of the present application is to provide a flexible attachment probe ground test active gravity unloading method, to construct a gravity unloading test system, to connect the mass center of the flexible rod and the mass center of the node with the motor respectively, to calculate and determine the force required by each motor according to the static equilibrium equation, to transmit the force generated by the motor through the suspension rope, the motor and the pulley set to act on the gravity of the flexible attachment probe, to complete the quantitative and accurate gravity unloading of the flexible attachment probe ground test, and to realize the real simulation of the dynamic characteristics of the flexible attachment structure.

[0004] The purpose of the present application is realized by the following technical scheme.

[0005] The flexible attachment probe ground test active gravity unloading method disclosed by the present application comprises the following steps:

[0006] Step 1: Constructing a flexible attachment probe structure. The flexible attachment probe comprises a body bearing plate, a buffer cylinder and a buffer support rigid structure, and a flexible connecting structure.

[0007] The body bearing plate is used for bearing equipment, and the equipment comprises a probe sensor and a calculation unit. The body bearing plate is a circular rigid plate, and contains rotating pair structures around the periphery.

[0008] The buffer cylinder is mainly composed of a cylinder shell, an inner container and a pipeline. The cylinder shell is mainly composed of a bearing seat mounted on an end cover, a cover and a bearing. The inner container is mainly composed of a vibration isolation pad, a spring and a shock pad, which is used to transmit external force to the cylinder and buffer the cylinder through the shock pad. The pipeline is used to deliver compressed air to the inside of the cylinder, and the external force is buffered through the compressed air.

[0009] The buffer support is in a ring structure, and the buffer cylinder and the buffer support are connected by a moving pair. During the attachment process, the buffer support moves under pressure, so that the impact and vibration of the buffer support are transmitted to the buffer cylinder, thereby achieving buffering during the attachment process.

[0010] The flexible connection structure is mainly composed of a flexible beam, and the front and rear ends of the flexible beam are respectively provided with rotating pair structures. The flexible beam is connected to the bearing plate and the buffer barrel through the rotating joints, and the rotating joints are respectively connected by springs.

[0011] By setting the position configuration of the rotating pair connection structure of the body bearing plate, the buffer cylinder, the buffer support and the flexible connection structure, the stable flexible attachment probe is realized.

[0012] Step 2: Under the action of gravity, the static deformation of the flexible attachment probe is large, and it is difficult to achieve nodding vibration by direct suspension. In order to unload the gravity of the flexible attachment probe, the signal generator outputs a voltage to drive a current power amplifier, the current power amplifier outputs a current to drive a motor, and the motor drives a rope to hoist the flexible attachment probe. The force system of the flexible attachment probe mainly consists of gravity, friction and motor output force. When the force system reaches equilibrium, the static equilibrium equation is:

[0013]

[0014] In the formula: N x represents the horizontal force of the flexible attachment probe, N y represents the vertical force of the flexible attachment probe, M node and M link respectively represent the mass of the flexible attachment probe connecting rod and node, F node and F link respectively represent the motor output force at different suspension positions, and g represents the acceleration of gravity.

[0015] By solving the static equilibrium equation, the rope tension at the suspension point is obtained, that is, the size of the force required by each motor is determined.

[0016] Step 3: Establish a gravity unloading ground test system for the flexible attachment probe. The test system includes a support device, a motion device and a control system.

[0017] The support device is composed of a high-strength cross beam and a movable chassis, which is mainly used to provide a support platform for the motion device to realize the movement of the microgravity simulation device.

[0018] The motion device comprises a connecting beam and a guide rail system. The connecting beam connects the guide rail to the support device, maintaining the stability of the guide rail. The guide rail consists of three parts: a suspension rope, a motor, and a pulley system. This enables the translational and rotational components to move in a plane. The suspension rope connects to the center of mass of the detector's flexible beam and the center of mass of each node, and is connected to the motor via the pulley system. Gravity compensation is achieved through the transmission of the suspension rope, motor, and pulley system. The pulley system ensures that the motor is kept away from the detector's location.

[0019] The control system includes a tension sensor, a laser displacement sensor, and a control computer. The tension sensor measures the tension of the suspension rope, the laser displacement sensor detects the displacement of the flexible attachment detector to evaluate the gravity unloading effect, and the control computer controls the motor force by inputting the tension and detector displacement, and displays various test parameters of force and displacement. Based on step 2, it calculates the static equilibrium equation to obtain the optimal motor output force, thereby realizing the gravity unloading of the flexible attachment detector in the ground test and achieving a realistic simulation of the dynamic characteristics of the flexible attachment structure.

[0020] As a preferred option, the flexible attachment detector adopts a 3-node configuration, which includes a main body load-bearing plate, 3 buffer cylinders and 3 buffer support rigid structures, as well as 3 sets of flexible connection structures.

[0021] The main body's load-bearing plate contains three rotating joint structures around its perimeter.

[0022] As a preferred embodiment, the suspension ropes are connected to the centroids of the three flexible beams and the centroids of the three nodes of the flexible attachment detector, and are connected to the six voice coil motors through six sets of pulleys.

[0023] Beneficial effects:

[0024] 1. The present invention discloses an active gravity unloading method for ground testing of a flexible attachment detector. The motors are connected to the center of mass of the flexible rod and the center of mass of the node, respectively. The force required by each motor is determined according to the static equilibrium equation. The gravity acting on the flexible attachment detector is dynamically unloaded through the transmission of the suspension rope, motor and pulley system, so as to realize the quantitative and accurate unloading of gravity in the ground test of the flexible attachment detector and realize the true simulation of the dynamic characteristics of the flexible attachment structure.

[0025] 2. The active gravity unloading method for ground testing of flexible attachment detector disclosed in this invention can achieve low-frequency motion within a limited range and compensate for large deformation of the structure by unloading gravity at multiple nodes.

[0026] 3. Due to the weak gravitational characteristics of the extraterrestrial environment, the active gravity unloading method for the ground test of the flexible attachment detector disclosed in this invention is not only applicable to weak gravitational celestial body exploration missions, but also to microgravity space environment missions.

[0027] 4. The flexible attached probe ground test active gravity unloading method disclosed in the present application has the characteristics of deformation and energy absorption, effectively releases the impact force of the star table on the probe during the attachment process, and avoids the rebound of the probe. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The flexible attached probe structure is designed.

[0029] Figure 2 The flexible attached probe ground gravity unloading method is designed.

[0030] Figure 3 The flexible attached probe ground test active gravity unloading method flow chart disclosed in the present application is designed. DETAILED DESCRIPTION

[0031] In order to better illustrate the purpose and advantages of the present application, the content of the present application will be further described below in combination with the drawings and examples.

[0032] As shown in the drawings, Figure 3 The flexible attached probe ground test active gravity unloading method disclosed in the present application is specifically implemented as follows:

[0033] Step 1: Flexible attached probe structure.

[0034] The flexible attached probe is designed as a 3-node configuration, which includes a body load-bearing plate, 3 buffer cylinders, 3 buffer support rigid structures, and 3 sets of flexible connection structures.

[0035] The body load-bearing plate is a circular rigid plate, which mainly functions to carry the probe sensor and computing unit and other equipment, and contains 3 rotating pairs around the periphery.

[0036] The buffer cylinder is composed of a roller shell, an inner container, and a pipeline, etc. The roller shell is composed of a bearing seat, a cover, and a bearing installed on the end cap. The inner container is a combined structure containing a vibration isolation pad, a spring, and a shock pad, which can transmit external force to the roller and buffer the roller through the shock pad. The pipeline is used to deliver compressed air to the inside of the roller to achieve buffering of external force.

[0037] The buffer support is a ring structure, and the buffer cylinder and the buffer support are connected by a moving pair. During the attachment process, the buffer support moves under pressure, causing the impact and vibration to be transmitted to the buffer cylinder, thereby achieving buffering during the attachment process.

[0038] The flexible connection structure is composed of a flexible beam, and the front and rear ends of the flexible beam have rotating pair structures respectively. The flexible beam is connected to the load-bearing plate and the buffer cylinder through rotating pairs, and the rotating joints are connected by springs respectively.

[0039] The body bearing plate, the buffer cylinder, the buffer support and the flexible connection structure are set as a 3-node configuration to realize the stability of the flexible attached probe.

[0040] Step 2: static equilibrium equation calculation to determine the force required by each motor.

[0041] Under the action of gravity, the static deformation of the structure is large, and it is difficult to realize the nodding vibration by direct suspension. In order to unload the gravity, the signal generator outputs the voltage to drive the current power amplifier, the current power amplifier outputs the current to drive the motor, and the motor drives the rope to hoist the flexible attached probe. The force system of the flexible attached probe is composed of gravity, friction and motor output force, and when the force system reaches equilibrium, the static equilibrium equation is:

[0042]

[0043] In the formula: N x represents the horizontal force of the flexible attached probe, N y represents the vertical force of the flexible attached probe, M node and M link respectively represent the masses of the three connecting rods and three nodes of the flexible attached probe, F node and F link respectively represent the motor output force connected to the three connecting rods and three nodes, g represents the acceleration of gravity, and is taken as 9.8 m / s 2 .

[0044] By solving the static equilibrium equation, the rope tension at the suspension point is obtained, that is, the motor output force size.

[0045] Step 3: Establish a gravity unloading ground test system to realize the real simulation of the dynamic characteristics of the flexible attached structure.

[0046] The test system includes a support device, a motion device and a control system, as shown in Figure 2 .

[0047] The support device is composed of a high-strength cross beam and a movable chassis, and its main function is to provide a support platform for the motion device to realize the movement of the microgravity simulation device.

[0048] The motion device comprises a connecting beam and a guide rail system, the connecting beam is used to connect the guide rail and the support device, and the guide rail is kept stable. The guide rail is composed of three parts of suspension rope, motor and pulley set, which realizes the planar motion of the translational and rotational parts. The voice coil motor is small in size and light in weight, and the output force is proportional to the current applied on the coil. It is a kind of linear actuator, so the suspension method of voice coil motor is used to unload the gravity of the flexible structure. Since the flexible attached probe adopts a 3-node configuration, the suspension ropes are connected to the centers of mass of the 3 flexible beams and the centers of mass of the 3 nodes of the probe respectively, and 6 sets of pulley sets are connected to 6 voice coil motors to complete the gravity compensation. The pulley set ensures that the motor is away from the area where the probe is located.

[0049] The control system comprises a tension sensor (SK301 can be selected), a laser displacement sensor (KEYENCE, LK-G80 and LK-GD500 can be selected) and a control computer. The tension sensor measures the tension of the suspension rope, the laser displacement sensor detects the displacement of the flexible attached probe, evaluates the gravity unloading effect, the control computer controls the size of the motor force by inputting the tension and the displacement of the probe, and displays the test parameters of force and displacement. The optimal motor output force is obtained by solving the static equilibrium equation, and the gravity unloading of the flexible attached probe ground test is completed.

[0050] The above specific description further describes the purpose, technical scheme and beneficial effects of the application. It should be understood that the above description is only a specific embodiment of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application should be included in the protection scope of the application.

Claims

1. A method for active gravity unloading for flexible lander attachment probe ground testing, characterized by: It comprises the following steps, Step 1: construct a flexible attachment probe structure; the flexible attachment probe comprises a body bearing plate, a buffer cylinder and a buffer support rigid body structure, and a flexible connection structure; The body bearing plate is used for carrying equipment, which comprises a probe sensor and a computing unit; the body bearing plate is a circular rigid plate, and a rotating pair structure is arranged around the body bearing plate; The buffer cylinder mainly comprises a roller shell, an inner container and a pipeline; the roller shell mainly comprises a bearing seat mounted on an end cover, a cover and a bearing; the inner container mainly comprises a vibration isolation pad, a spring and a shock pad, and is used for transmitting external force to the roller and buffering the roller through the shock pad; the pipeline is used for conveying compressed air to the inside of the roller, and the external force is buffered through the compressed air; The buffer support is in an annular structure, and the buffer cylinder and the buffer support are connected by a moving pair; during the attachment process, the buffer support moves under pressure, so that the impact and vibration of the buffer support are transmitted to the buffer cylinder, and the attachment process is buffered; The flexible connection structure mainly comprises a flexible beam, rotating pair structures are arranged at the front end and the rear end of the flexible beam respectively, the flexible beam is connected with the bearing plate and the buffer cylinder through the rotating pair, and the rotating joints are connected by springs respectively; By arranging the position configuration of the rotating pair connection structure of the body bearing plate, the buffer cylinder, the buffer support and the flexible connection structure, the stability of the flexible attachment probe is realized; Step 2: in order to unload the gravity of the flexible attachment probe, a signal generator outputs a voltage to drive a current power amplifier, the current power amplifier outputs a current to drive a motor, and the motor drives a rope to hoist the flexible attachment probe; The force system of the flexible attachment probe mainly comprises gravity, friction and motor output force; when the force system reaches equilibrium, the static equilibrium equation is: where N x represents the horizontal force of the flexible attachment probe, N y represents the vertical force of the flexible attachment probe, M node and M link represent the mass of the flexible attachment probe link and node, respectively, F node and F link represent the motor output force at different suspension positions, and g represents the acceleration of gravity. By solving the static equilibrium equation, the rope tension of the suspension point is obtained, that is, the force size required by each motor is determined; Step 3: establish a gravity unloading ground test system for the flexible attachment probe; the test system comprises a support device, a movement device and a control system; The support device is composed of a high-strength cross beam and a movable chassis, and is mainly used for providing a support platform for the movement device to realize the movement of the microgravity simulation device; The movement device comprises a connecting beam and a guide rail system; the connecting beam is used to connect the guide rail and the support device to keep the guide rail stable; the guide rail is composed of a suspension rope, a motor and a pulley set, and is used to realize the movement of a translating + rotating component in a plane; the suspension rope is connected with the mass center of the flexible beam and the mass center of the node respectively, and is connected with the motor through the pulley set; the gravity compensation is realized through the transmission of the suspension rope, the motor and the pulley set; the pulley set ensures that the motor is away from the area where the probe is located; The control system comprises a tension sensor, a laser displacement sensor and a control computer; the tension sensor measures the tension of the suspension rope, the laser displacement sensor detects the displacement of the flexible attachment probe, evaluates the gravity unloading effect, and the control computer controls the force size of the motor through the input of the tension and the displacement of the probe, and displays the test parameters of the force and the displacement; according to the calculation of the static equilibrium equation in step 2, the optimal motor output force is obtained, the gravity unloading of the flexible attachment probe ground test is realized, and the real simulation of the dynamic characteristics of the flexible attachment structure is realized.

2. The flexible lander test active gravity unloading method of claim 1, wherein: The flexible attachment probe adopts a 3-node configuration, and includes 1 body bearing plate, 3 buffer cylinders and 3 buffer support rigid structures, and 3 sets of flexible connection structures. The body bearing plate contains 3 rotating pair structures around.

3. The flexible lander test active gravity unloading method of claim 1 or 2, wherein: The suspension ropes are connected with the centers of mass of the 3 flexible beams and the 3 nodes of the flexible attachment probe respectively, and are connected with 6 voice coil motors through 6 pulley sets.

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