Grounding test device, test piece control method and program

Abstract

To provide a grounding test device, a sample control method, and a program in which gravity compensation is realized at high accuracy by connecting an elastic body and an actuator in parallel and compensating for load fluctuation of the elastic body with the actuator.SOLUTION: A grounding test device 1 comprises: a spring 20; a direct-acting actuator; a position detector 70; and a controller. The spring 20 is connected to a top face of a sample 10 to suspend the sample 10. The direct-acting actuator is connected to a lateral face of the sample 10 to apply force in a height direction to the sample 10. The position detector 70 detects a height of the sample 10 and outputs sample position information indicating the height of the sample 10. The controller outputs a command value for driving the direct-acting actuator, acquires the sample position information and calculates the height of the sample 10, and drives the direct-acting actuator to accelerate the sample 10 to a descending speed if the height of the sample 10 is the same as a control position or higher, and drives the direct-acting actuator to generate force for cancelling the force generated by displacement of the spring 20 if the height of the sample 10 is lower than the control position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a grounding test device, a test piece control method, and a program. [Background technology]

[0002] Experiments may be conducted under terrestrial gravity to confirm whether the behavior of a flying object before and after landing on a granular medium in a zero-gravity or microgravity environment is as expected at the time of design. In this case, gravity compensation is performed to apply a load in the opposite direction to gravity to the test object, creating a zero-gravity or microgravity environment, and a test object simulating the flying object is lowered into the granular medium and allowed to touch down on the granular medium.

[0003] Patent document 1 describes a motion testing device comprising: a reference plate made of a magnetic material and having a generally horizontal lower surface; a mover that is supported in contact with the lower surface of the reference plate by magnetic attraction and can move freely within a two-dimensional plane along the lower surface; and a suspension wire that is suspended downward from the mover and supports a test object in a suspended state; the mover having a magnetic field generating means that generates the magnetic attraction force, a contact holding means that mechanically contacts the lower surface of the reference plate, a positional deviation detection means that detects the relative positional deviation between the test object and the mover in a plane parallel to the reference plate, and an active driving means that drives the mover along the lower surface of the reference plate so as to minimize the positional deviation detected by the positional deviation detection means. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-218471 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the motion testing device described in Patent Document 1, the test object is connected to a slider having a spring and a damper via a suspension line, the tension of the suspension line is measured by a load cell, and the tension is controlled by a motor connected in series with the spring, thereby achieving gravity compensation for the test object. However, when the spring and motor are connected in series as in the motion testing device described in Patent Document 1, there is a problem that if the spring stiffness is low, the amount of spring displacement at the time of balance becomes large, resulting in an increase in the size of the entire device, and if the spring stiffness is high, the load fluctuation when the test object is displaced from the balance point becomes large, resulting in a decrease in gravity simulation accuracy.

[0006] The present disclosure has been made in consideration of such problems, and aims to provide a grounding test device, a test specimen control method, and a program that can achieve gravity compensation with high precision by connecting an elastic body and an actuator in parallel and compensating for load fluctuations on the elastic body with the actuator. [Means for solving the problem]

[0007] To achieve the above object, the ground test apparatus according to the present disclosure includes a spring, a linear actuator, a position detector, and a controller. The spring is connected to the top surface of the test specimen and suspends the test specimen. The linear actuator is connected to the side of the test specimen and applies a force to the test specimen in the height direction. The position detector detects the height of the test specimen and outputs test specimen position information indicating the height of the test specimen. The controller outputs a command value to drive the linear actuator, acquires the test specimen position information from the position detector, calculates the height of the test specimen, and drives the linear actuator to accelerate the test specimen to a descent speed if the height of the test specimen is equal to or higher than a control position, and drives the linear actuator to generate a force that cancels out the force generated by the displacement of the spring if the height of the test specimen is lower than the control position. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a grounding test device, a test specimen control method, and a program that can achieve gravity compensation with high precision by connecting an elastic body and an actuator in parallel and compensating for load fluctuations on the elastic body with the actuator. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a side view showing a grounding test device according to a first embodiment; [Figure 2] 1 is a cross-sectional view showing a grounding test device according to a first embodiment; [Figure 3] FIG. 1 is a block diagram showing the configuration of a grounding test device according to a first embodiment. [Figure 4] 1 is a diagram showing the position of the test piece and the elongation of the spring according to the first embodiment; [Figure 5] Flowchart showing the specimen control process according to the first embodiment [Figure 6] Schematic diagram showing a specimen and a spring according to the second embodiment. [Figure 7] Flowchart showing the specimen control process according to the second embodiment [Figure 8] FIG. 10 is a side view showing a grounding test device according to a third embodiment. [Figure 9] A block diagram showing the configuration of a grounding test device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Embodiment 1) A grounding test apparatus 1 according to a first embodiment of the present disclosure will be described with reference to FIGS. 1 to 5. Identical or corresponding parts in the drawings are designated by the same reference numerals. The grounding test apparatus 1 according to the first embodiment is a test apparatus for conducting experiments on the behavior of an object in a zero-gravity or microgravity environment.

[0011] Fig. 1 is a side view showing a grounding test apparatus 1 according to a first embodiment. As shown in Fig. 1, the grounding test apparatus 1 includes a test specimen 10 that is grounded to observe its behavior, a spring 20 that suspends the test specimen 10, a linear guide 30 and a linear rail 40 that restrict the movement of the test specimen 10, a linear motor mover 50 and a linear motor stator 60 that apply thrust to the test specimen 10, a position detector 70 and a position detection pattern 80 that measure the position of the test specimen 10, a granular medium 90 that comes into contact with the test specimen 10, and a stand 100 that suspends the test specimen 10. The description will be given assuming that the up-down direction in Fig. 1 is the Z direction.

[0012] The specimen 10 is a test object whose behavior is observed by placing it on a granular medium 90. A linear guide 30 is arranged on the specimen 10, and the specimen 10 is movable in the Z direction along a linear rail 40.

[0013] The spring 20 is an elastic body that suspends the specimen 10. One end of the spring 20 is connected to the top surface of the specimen 10, and the other end is connected to the mount 100.

[0014] Fig. 2 is a cross-sectional view showing the grounding test device 1 according to embodiment 1. Fig. 2 is a cross-sectional view taken along the line AA in Fig. 1. As shown in Figs. 1 and 2, four linear guides 30 are arranged on the surface of the DUT 10 facing the stand 100, i.e., on the side surface of the DUT 10, and each linear guide 30 engages with a linear rail 40 to slide in the Z direction.

[0015] Two linear rails 40 are arranged on the frame 100, each extending in the Z direction and engaging with two of the linear guides 30 respectively.

[0016] The linear guide 30 and the linear rail 40 restrict the movement of the specimen 10 in the Z direction. The specimen 10, the linear guide 30, and the linear rail 40 are positioned so that the lower end of the specimen 10 in the Z direction comes into contact with the granular medium 90 before the linear guide 30 reaches the lowermost end of the linear rail 40.

[0017] The linear motor mover 50 is a linear motor that is arranged on the side of the specimen 10 and moves in the Z direction when energized.

[0018] The linear motor stator 60 is disposed on the mount 100 facing the linear motor mover 50, and is a linear motor that moves in the Z direction when energized.

[0019] The linear motor mover 50 and the linear motor stator 60 apply a thrust force in the Z direction to the specimen 10. The linear motor mover 50 and the linear motor stator 60 are arranged in positions where they can apply a thrust force throughout the entire movable range of the specimen 10 that is limited by the linear guide 30 and the linear rail 40.

[0020] The linear motor mover 50 and linear motor stator 60 are preferably, but not limited to, coreless linear motors with small magnetic attraction force that can reduce the sliding friction force between the linear guide 30 and linear rail 40. The sliding friction force between the linear guide 30 and linear rail 40 may be compensated for by the thrust of the linear motor mover 50 and linear motor stator 60.

[0021] The position detector 70 is a sensor that photographs the position detection pattern and performs image processing on the photographed image to detect the position of the specimen 10 relative to the position detection pattern 80. The position detector 70 is placed on the surface of the specimen 10 that does not face the stand 100, in an orientation that allows it to photograph the position detection pattern.

[0022] The position detection pattern 80 is an image pattern captured by the position detector 70. The position detection pattern 80 is disposed on the gantry 100 and extends in the Z direction.

[0023] The granular medium 90 is a medium that simulates the ground on which the specimen 10 descends and touches down, and on which a spacecraft descends. The granular medium 90 is placed directly below the specimen 10.

[0024] The mount 100 suspends the specimen 10 via the spring 20. On the mount 100, the spring 20, the linear rail 40, the linear motor stator 6, and the position detection pattern 80 are arranged.

[0025] Fig. 3 is a block diagram showing the configuration of the grounding test device 1. As shown in Fig. 3, the grounding test device 1 includes a controller 110 that calculates a command value indicating a drive current, and an amplifier 120 that outputs the drive current.

[0026] The controller 110 calculates a command value indicating the drive current to be output to the linear motor mover 50 or the linear motor stator 60. The controller 110 is connected to the position detector 70 and the amplifier 120, and acquires the position of the specimen 10, i.e., specimen position information indicating the height of the specimen 10, from the position detector 70, calculates a linear motor thrust command value, and outputs it to the amplifier 120. The controller 110 is a circuit that may include an integrated circuit, but is not limited to this.

[0027] The amplifier 120 outputs a drive current to be output to the linear motor mover 50 or the linear motor stator 60. The amplifier 120 is connected to the controller 110, the linear motor mover 50, and the linear motor stator 60, acquires a linear motor thrust command value output from the controller 110, and outputs a drive current to the linear motor mover 50 or the linear motor stator 60 according to the linear motor thrust command value.

[0028] A specific description will be given of the linear motor thrust command value calculated by the controller 110. The controller 110 calculates the position of the specimen 10 from the specimen position information acquired from the position detector 70, and outputs a linear motor thrust command value that moves the specimen 10 to an arbitrary position based on the calculated position.

[0029] The controller 110 calculates the speed of the specimen 10 from the specimen position information acquired from the position detector 70, and outputs a linear motor thrust command value that sets the speed of the specimen 10 to an arbitrary speed based on the calculated speed. A control method including PID (Proportional-Integral-Differential) control can be used as a method for calculating the linear motor thrust command value that sets the position or speed of the specimen 10 to an arbitrary position or speed, respectively, but the control method is not limited to this.

[0030] The linear motor thrust command value for gravity compensation calculated by the controller 110 will now be described. FIG. 4 is a diagram showing the position of the specimen 10 and the extension of the spring 20. The left side of FIG. 4 shows a case where the specimen 10 is not suspended. The center of FIG. 4 shows a case where the specimen 10 is suspended and there is no thrust. When the controller 110 does not output a linear motor thrust command value, the amplifier 120 does not output drive currents to the linear motor mover 50 and the linear motor stator 60, and the linear motor mover 50 and the linear motor stator 60 do not generate thrust, the specimen 10 comes to rest at a position where the gravity acting on the specimen 10 and the force of the spring 20 are balanced, i.e., at the equilibrium point. The extension amount z0 of the spring 20 at this time is expressed by the following equation (1): z0=Mg / k (1) Here, M is the mass of the specimen 10, g is the gravitational acceleration, and k is the spring constant of the spring 20.

[0031] 4 shows the case where the specimen 10 is displaced. When the specimen 10 is displaced by Δz from the equilibrium point, the amount of change ΔF in the force of the spring 20 is expressed by the following equation (2). ΔF=kΔz (2)

[0032] The controller 110 calculates a linear motor thrust command value that causes the linear motor mover 50 or the linear motor stator 60 to generate a thrust that cancels out the amount of change in force due to the spring 20, i.e., a linear motor thrust command value that performs gravity compensation. The controller 110 calculates the displacement Δz of the specimen 10 from the specimen position information acquired from the position detector 70, and calculates the amount of change ΔF in force due to the spring 20 using the value of the spring constant k according to equation (2), and calculates a linear motor thrust command value that causes the linear motor mover 50 or the linear motor stator 60 to generate a thrust that cancels out ΔF, i.e., kΔz.

[0033] The controller 110 may calculate a linear motor thrust command value that generates a constant downward thrust in the Z direction that is independent of the displacement Δz of the specimen 10, in addition to the thrust that cancels out ΔF. By generating a constant downward thrust in the Z direction, it is possible to simulate a microgravity environment.

[0034] The value of the spring constant k of the spring 20 will be explained. The upper limit of the displacement of the specimen 10 from the equilibrium point is defined as the upper limit of the displacement Δz lim and the upper limit of the thrust of the linear motor mover 50 or the linear motor stator 60 is F max The upper limit of displacement Δz lim is determined from the required value of the movable range of the specimen 10 that requires a zero-gravity state. In order to cancel the displacement amount of the force by the spring 20 using the linear motor mover 50 or the linear motor stator 60, the spring constant k of the spring 20 is within the range shown in the following formula (3). When simulating a microgravity environment, the amount of microgravity is subtracted from the upper thrust limit value. k <F max / Δz lim (3)

[0035] The allowable extension of spring 20 from the balanced state is z 0lim In order for the extension of the spring 20 to fall within the allowable amount, the spring constant k of the spring 20 is within the range shown in the following equation (4). k>Mg / z 0lim (4)

[0036] From equations (3) and (4), the spring constant k of the spring 20 is within the range shown in equation (5) below. Mg / z 0lim <k<F max / Δz lim (5)

[0037] The spring constant of the spring 20 may be designed so that the equilibrium point of the specimen 10 is near the position where the specimen 10 stops due to the ground reaction force. By designing it in this way, the time that the specimen 10 remains at a position displaced from the equilibrium point is shortened, and it is possible to prevent the linear motor mover 50 or the linear motor stator 60 from continuing to generate a thrust that cancels out the force of the spring 20, thereby preventing an increase in the load.

[0038] Fig. 5 is a flowchart showing a specimen control process executed by the grounding test apparatus 1 according to embodiment 1. The specimen control process executed by the grounding test apparatus 1 will be described with reference to the flowchart in Fig. 5. It is assumed that an experiment is carried out in a simulated zero-gravity environment.

[0039] When the DUT control process is started, the controller 110 of the grounding test device 1 outputs a linear motor thrust command value, drives the linear motor mover 50 or the linear motor stator 60 via the amplifier 120, and moves the DUT 10 to the start position (step S101). The start position is higher than the control position.

[0040] When the specimen 10 is moved to the start position, the controller 110 acquires specimen position information from the position detector 70 and determines whether the position of the specimen 10 is equal to or greater than the control position (step S102).

[0041] If it is determined that the position of the specimen 10 is equal to or greater than the control position (step S102: YES), the controller 110 outputs a linear motor thrust command value that accelerates the speed of the specimen 10 to a descent speed (step S103), and returns to step S102. The descent speed is an arbitrary speed that simulates the descent of the specimen 10. Steps S102 and S103 are referred to as an acceleration phase.

[0042] If it is determined that the position of the specimen 10 is lower than the control position (step S102: NO), the controller 110 outputs a linear motor thrust command value that generates a thrust force, i.e., ΔF=kΔz, in the linear motor mover 50 or the linear motor stator 60 to cancel out the change in force due to the spring 20 (step S104).

[0043] When the linear motor thrust command value that cancels the amount of change in force by the spring 20 is output, the controller 110 acquires the specimen position information from the position detector 70 and determines whether the specimen 10 has come to a standstill (step S105).

[0044] If it is determined that the object is not stationary (step S105: NO), the process returns to step S104. If it is determined that the object is stationary (step S105: YES), the test piece control process ends. Steps S103 to S105 are referred to as the gravity compensation phase.

[0045] With the above configuration and by executing the test piece control process, the grounding test device 1 according to the first embodiment can realize gravity compensation with high accuracy by connecting the elastic body and the actuator in parallel and compensating for the load fluctuation of the elastic body with the actuator.

[0046] The grounding test apparatus 1 according to the first embodiment accelerates the specimen 10 in the acceleration phase and compensates for the gravity acting on the specimen in the gravity compensation phase, thereby achieving high gravity simulation accuracy even when the specimen 10 is an imitation of a flying object including a spacecraft having a mass ranging from several hundred kilograms to several tons.

[0047] If the specimen is suspended only by the suspension unit including the cable and the actuator, the ground reaction force will cause tension loss in the suspension unit at the moment of touchdown, which may result in a decrease in the accuracy of the microgravity simulation.The ground test device 1 according to the first embodiment prevents tension loss by suspending the specimen 10 using the spring 20, thereby achieving high accuracy in the gravity simulation.

[0048] (Embodiment 2) The grounding test device 1 according to the second embodiment will be described with reference to Fig. 6 and Fig. 7. The grounding test device 1 according to the second embodiment cancels out the amount of change in force due to the spring 20 and applies a thrust weighted by an external factor to the test piece 10.

[0049] A real vehicle is equipped with a propellant tank containing propellant fluid. The propellant fluid vibrates within the tank due to acceleration / deceleration during descent or impact upon landing. This applies dynamic internal fluid vibration loads to the inner wall surface of the propellant tank, potentially affecting the behavior of the entire vehicle upon landing. Because the internal fluid vibration loads differ significantly between zero- or microgravity environments and 1G environments on Earth, it is difficult to reproduce the fluid behavior or the coupled phenomena with the behavior of the test specimen in a 1G environment on Earth.

[0050] In addition to the internal fluid vibration load of the actual flying object, the structural vibration load, which is vibration of the structure of the actual flying object, and the load of the control actuator of the actual flying object may also affect the behavior of the entire flying object when it touches the ground.

[0051] Fig. 6 is a schematic diagram showing a specimen 10 and a spring 20 of a ground test device 1 according to embodiment 2. As shown in Fig. 6, vibration of the propellant or structure can be expressed by a physical model including a vibrating rigid body, stiffness, or damping inside the specimen 10. The control actuator load can be expressed as a load element due to the linear motor mover 50 or the linear motor stator 60.

[0052] The controller 110 calculates a linear motor thrust command value that generates a thrust in the linear motor mover 50 or the linear motor stator 60 that cancels the amount of change in the force of the spring 20, that is, a linear motor thrust command value that performs gravity compensation, and also calculates an external factor weight F d The controller 110 calculates the displacement Δz of the specimen 10 from the specimen position information acquired from the position detector 70, calculates the amount of change ΔF in the force of the spring 20 using the value of the spring constant k according to equation (2), and calculates the thrust force that cancels out ΔF, i.e., kΔz and the external factor load F d and a linear motor thrust command value to be generated in the linear motor mover 50 or the linear motor stator 60 is calculated.

[0053] External factor weighting F d can be calculated from the physical model shown in FIG. 6, the position information of the specimen, the value of the thrust applied by the linear motor mover 50 or the linear motor stator 60, or the measurement value by a load cell (not shown) added to the specimen 10, but is not limited to these.

[0054] Fig. 7 is a flowchart showing the specimen control process executed by the grounding test apparatus 1 according to embodiment 2. The specimen control process executed by the grounding test apparatus 1 will be described with reference to the flowchart in Fig. 7. Steps S101 to S103 and step S105 are the same as those in the flowchart in Fig. 5, and therefore description thereof will be omitted.

[0055] When it is determined in step S102 that the position of the specimen 10 is lower than the control position (step S102: NO), the controller 110 calculates the thrust and the external load that cancel out the change in the force caused by the spring 20, i.e., ΔF=kΔz+F d The linear motor thrust command value for generating the linear motor thrust force in the linear motor mover 50 or the linear motor stator 60 is output (step S104').

[0056] With the above configuration, the grounding test device 1 according to the second embodiment achieves the same effects as the grounding test device 1 according to the first embodiment.

[0057] According to the ground contact test device 1 of the second embodiment, it is possible to perform a ground contact experiment in zero gravity or microgravity with higher accuracy by reproducing the internal fluid vibration load, structural vibration load, and actuator load of an actual flying object.

[0058] (Embodiment 3) The grounding test apparatus 1 according to the third embodiment will be described with reference to Fig. 8 and Fig. 9. In the grounding test apparatus 1 according to the third embodiment, a test piece 10 is provided with a subsystem, and gravity compensation is performed simultaneously between the main system and the subsystem.

[0059] Fig. 8 is a side view showing the grounding test apparatus 1 according to embodiment 3. As shown in Fig. 8, in addition to the components provided in the grounding test apparatus 1 according to embodiment 1, the grounding test apparatus 1 includes landing legs 11 simulating the landing legs of a spacecraft, a buffer unit 12 connecting the DUT 10 and the landing legs 11, a suspender unit 21 for suspending the landing legs 11, a rotary motor 51 for winding up or unwinding the suspender unit 21, a rotation angle detector 71 for detecting the rotation angle of the rotary motor 51, and a load cell 72 for detecting the force acting on the suspender unit 21.

[0060] The landing leg 11 is a test specimen that simulates the landing leg of a spacecraft. The landing leg 11 touches the granular medium 90.

[0061] The buffer 12 is a test piece simulating a buffer member of a spacecraft, with one end connected to the specimen 10 and the other end connected to the landing leg 11. The buffer 12 may have a structure that supports the landing leg rotatably and retractably, and absorbs shock, similar to the buffer member of a spacecraft. The landing leg 11 and the buffer 12 constitute a subsystem of the specimen 10.

[0062] The suspender 21 is a linear or thread-like member having one end connected to the landing leg 11 and the other end retractably connected to the rotation motor 51, and may include, but is not limited to, a cable. One end of the suspender 21 is preferably connected to the center of gravity of the landing leg 11, but is not limited to this.

[0063] The rotation motor 51 is disposed on the pedestal 100, and rotates when energized to wind up or unwind the suspender 21.

[0064] The rotation angle detector 71 is disposed on the rotary motor 51 and is a sensor that detects the rotation angle of the rotary motor 51. The rotation angle detector 71 outputs rotation angle information that indicates the rotation angle of the rotary motor 51.

[0065] The load cell 72 is disposed on the suspending unit 21 and is a tension detector that detects the tension acting on the suspending unit 21. The load cell 72 outputs tension information that indicates the tension acting on the suspending unit 21.

[0066] Fig. 9 is a block diagram showing the configuration of the grounding test apparatus 1 according to embodiment 3. As shown in Fig. 9, the grounding test apparatus 1 includes an amplifier 121 that outputs a drive current to the rotary motor 51 in addition to the configuration included in the grounding test apparatus 1 according to embodiment 1.

[0067] The controller 110 calculates a command value indicating the drive current to be output to the linear motor mover 50 or the linear motor stator 60, and also calculates a command value indicating the drive current to be output to the rotary motor 51. The controller 110 is connected to the position detector 70, the rotation angle detector 71, the load cell 72, the amplifier 120, and the amplifier 121, and acquires specimen position information from the position detector 70, rotation angle information indicating the rotation angle of the rotary motor 51 from the rotation angle detector 71, and tension information indicating the tension acting on the suspension unit 21 from the load cell 72, calculates a linear motor thrust command value and outputs it to the amplifier 120, and calculates a rotary motor thrust command value and outputs it to the amplifier 121.

[0068] The amplifier 121 outputs a drive current to be output to the rotary motor 51. The amplifier 121 is connected to the controller 110 and the rotary motor 51, acquires a rotary motor thrust command value output from the controller 110, and outputs a drive current to the rotary motor 51 according to the rotary motor thrust command value.

[0069] The controller 110 calculates a rotary motor thrust command value for performing gravity compensation, similar to the process of calculating a linear motor thrust command value for performing gravity compensation in the first embodiment.

[0070] With the above configuration, the grounding test device 1 according to the third embodiment achieves the same effects as the grounding test device 1 according to the first embodiment.

[0071] According to the grounding test device 1 of the third embodiment, even if the test specimen 10 is equipped with a subsystem, gravity compensation can be performed on the main system and the subsystem of the test specimen 10, making it possible to conduct a grounding experiment in zero gravity or microgravity with higher accuracy.

[0072] (Variation) The embodiments of the present disclosure are not limited to those described above and may be modified. For example, while the ground test device 1 has been described as including a linear motor mover 50 and a linear motor stator 60, the present invention is not limited to this. Any linear actuator, not limited to a linear motor, may also be included. The linear actuator may include a ball screw mechanism or a rack-and-pinion mechanism. However, backdrivability is required because friction within the mechanism may impede the behavior of the test specimen when a ground reaction force is applied, reducing the accuracy of the simulation. When using a linear mechanism with low backdrivability, such as a ball screw mechanism or a rack-and-pinion mechanism, a load cell may be added to the non-drive side mechanism, and force control may be performed based on the output value of the load cell.

[0073] The test specimen control process executed by the grounding test device 1 has been described as an experiment conducted in a simulated zero-gravity environment, but is not limited to this. An experiment may also be conducted in a simulated microgravity environment. In this case, the controller 110 calculates a linear motor thrust command value that generates a constant downward thrust in the Z direction that simulates microgravity, in addition to a thrust that cancels out ΔF. Furthermore, since acceleration due to microgravity occurs during the gravity compensation phase, speed control is performed in the acceleration phase, in which the descent speed is set to a speed obtained by subtracting the acceleration from the start of the gravity compensation phase until touchdown from the descent speed in a zero-gravity environment.

[0074] When the specimen control process is started, the controller 110 outputs a linear motor thrust command value, drives the linear motor mover 50 or the linear motor stator 60 via the amplifier 120, and moves the specimen 10 to the start position, but this is not limitative. The specimen 10 may also be moved to the start position by an external force, including a winch.

[0075] Although the spring constant of the spring 20 may be designed so that the balance point of the specimen 10 is near the position where the specimen 10 stops due to the ground reaction force, this is not limited to this. Instead of changing the spring constant of the spring 20, the height of the point where the spring 20 is fixed to the base 100 may be changed.

[0076] Although the earth test device 1 is described as including the granular medium 90, the present invention is not limited to this. The medium with which the DUT 10 is grounded is not limited to a granular one, and may be any medium.

[0077] In the second embodiment, the actual flying vehicle is equipped with a propellant tank and has a propellant fluid therein, but this is not limited to this. Any fluid other than propellant may be provided, and the internal fluid vibration load caused by that fluid may be reproduced.

[0078] In the third embodiment, the ground test device 1 is described as including the rotary motor 51, but this is not limited to this. Any actuator other than the rotary motor 51 may be included. In this case, the ground test device 1 includes an operation amount detector instead of the rotation angle detector 71 that detects the operation amount of the actuator and outputs operation amount information indicating the detected operation amount.

[0079] In the third embodiment, the controller 110 calculates a rotary motor thrust command value for performing gravity compensation in the same manner as in the first embodiment, but this is not limited to this. The mass of the landing gear 11 is typically several tens of kilograms, and gravity compensation can be performed by a known method without performing gravity compensation similar to that in the first embodiment. The mass of the buffer unit 12 is even smaller than that of the landing gear 11, and gravity compensation may not be required.

[0080] Various aspects of the present disclosure are summarized below as appendices.

[0081] (Appendix 1) a spring connected to the upper surface of the specimen and suspending the specimen; a linear actuator connected to a side surface of the specimen and applying a force to the specimen in a height direction; a position detector that detects the height of the specimen and outputs specimen position information indicating the height of the specimen; a controller that outputs a command value for driving the linear motion actuator, the controller acquires the specimen position information from the position detector and calculates the height of the specimen, and when the height of the specimen is equal to or higher than a control position, drives the linear actuator to accelerate the specimen to a descending speed, and when the height of the specimen is lower than the control position, drives the linear actuator to generate a force that cancels out the force generated by the displacement of the spring. Grounding test equipment. (Appendix 2) a spring constant of the spring is within a range determined by an upper limit of displacement of the spring in a balanced state, an upper limit of displacement of the test piece from a balanced point, and an upper limit of force generated by the linear motion actuator. 1. The earthing test device described in Appendix 1. (Appendix 3) the controller calculates an external load including one or more of an internal fluid vibration load of the flying object, a structural vibration load, and a load of a control actuator provided in the flying object, and drives the linear actuator to reproduce the external load and apply the reproduced external load to the specimen; 1. The earthing test apparatus according to claim 1 or 2. (Appendix 4) the specimen includes a subsystem; a suspension unit that suspends the subsystem; an actuator for applying a height force to the subsystem; an operation amount detector that detects an operation amount of the actuator and outputs operation amount information indicating the operation amount; a tension detector that detects the tension acting on the suspension part and outputs tension information indicating the tension acting on the suspension part, the controller acquires the operation amount information from the operation amount detector and the tension information from the tension detector, and calculates and outputs a command value for driving the actuator based on the acquired operation amount information and tension information. 4. The earthing test apparatus according to any one of claims 1 to 3. (Appendix 5) further comprising an amplifier connected to the linear motion actuator and the controller, the amplifier outputting a drive current for driving the linear motion actuator based on a command value for driving the linear motion actuator output by the controller; 5. The earthing test apparatus according to any one of claims 1 to 4. (Appendix 6) the controller drives the linear actuator to generate a constant downward force in the height direction; 6. The earth testing device of any one of appendices 1 to 5. (Appendix 7) Further comprising a medium with which the specimen comes into contact; 7. The earth testing device of any one of appendices 1 to 6. (Appendix 8) calculating the height of the specimen by acquiring specimen position information from a position detector that detects the height of the specimen and outputs specimen position information indicating the height of the specimen; When the height of the specimen is equal to or higher than the control position, a linear actuator connected to a side surface of the specimen and applying a force in a height direction to the specimen is driven to accelerate the specimen to a descending speed; When the height of the specimen is lower than the control position, the linear actuator is driven to generate a force that cancels out a force generated by the displacement of a spring that is connected to the upper surface of the specimen and suspends the specimen. Specimen control method. (Appendix 9) On the computer, a position detector that detects the height of the specimen and outputs specimen position information indicating the height of the specimen, and acquires the specimen position information to calculate the height of the specimen; When the height of the specimen is equal to or higher than the control position, a linear actuator connected to a side surface of the specimen and applying a force in a height direction to the specimen is driven to accelerate the specimen to a descending speed; When the height of the specimen is lower than the control position, the linear actuator is driven to generate a force that cancels out a force generated by the displacement of a spring that is connected to the upper surface of the specimen and suspends the specimen. program. [Explanation of symbols]

[0082] 1 Ground test equipment, 10 test specimen, 11 landing leg, 12 buffer section, 20 spring, 21 suspension section, 30 linear guide, 40 linear rail, 50 linear motor mover, 51 rotation motor, 60 linear motor stator, 70 position detector, 71 rotation angle detector, 72 load cell, 80 position detection pattern, 90 granular medium, 100 stand, 110 controller, 120, 121 amplifier.

Claims

1. a spring connected to the upper surface of the specimen and suspending the specimen; a linear actuator connected to a side surface of the specimen and applying a force to the specimen in a height direction; a position detector that detects the height of the specimen and outputs specimen position information indicating the height of the specimen; a controller that outputs a command value for driving the linear motion actuator, the controller acquires the specimen position information from the position detector and calculates the height of the specimen, and when the height of the specimen is equal to or higher than a control position, drives the linear actuator to accelerate the specimen to a descending speed, and when the height of the specimen is lower than the control position, drives the linear actuator to generate a force that cancels out the force generated by the displacement of the spring. Grounding test equipment.

2. a spring constant of the spring is within a range determined by an upper limit of displacement of the spring in a balanced state, an upper limit of displacement of the test piece from a balanced point, and an upper limit of force generated by the linear motion actuator.

2. The ground test device of claim 1.

3. the controller calculates an external load including one or more of an internal fluid vibration load of the flying object, a structural vibration load, and a load of a control actuator provided in the flying object, and drives the linear actuator to reproduce the external load and apply the reproduced external load to the specimen; 3. The grounding test device according to claim 1 or 2.

4. the specimen includes a subsystem; a suspension unit that suspends the subsystem; an actuator for applying a height force to the subsystem; an operation amount detector that detects an operation amount of the actuator and outputs operation amount information indicating the operation amount; a tension detector that detects the tension acting on the suspension part and outputs tension information indicating the tension acting on the suspension part, the controller acquires the operation amount information from the operation amount detector and the tension information from the tension detector, and calculates and outputs a command value for driving the actuator based on the acquired operation amount information and tension information.

3. The grounding test device according to claim 1 or 2.

5. further comprising an amplifier connected to the linear motion actuator and the controller, the amplifier outputting a drive current for driving the linear motion actuator based on a command value for driving the linear motion actuator output by the controller; 3. The grounding test device according to claim 1 or 2.

6. the controller drives the linear actuator to generate a constant downward force in the height direction; 3. The grounding test device according to claim 1 or 2.

7. Further comprising a medium with which the specimen comes into contact; 3. The grounding test device according to claim 1 or 2.

8. calculating the height of the specimen by acquiring specimen position information from a position detector that detects the height of the specimen and outputs specimen position information indicating the height of the specimen; When the height of the specimen is equal to or higher than the control position, a linear actuator connected to a side surface of the specimen and applying a force in a height direction to the specimen is driven to accelerate the specimen to a descending speed; When the height of the specimen is lower than the control position, the linear actuator is driven to generate a force that cancels out a force generated by the displacement of a spring that is connected to the upper surface of the specimen and suspends the specimen. Specimen control method.

9. On the computer, a position detector that detects the height of the specimen and outputs specimen position information indicating the height of the specimen, and acquires the specimen position information to calculate the height of the specimen; When the height of the specimen is equal to or higher than the control position, a linear actuator connected to a side surface of the specimen and applying a force in a height direction to the specimen is driven to accelerate the specimen to a descending speed; When the height of the specimen is lower than the control position, the linear actuator is driven to generate a force that cancels out a force generated by the displacement of a spring that is connected to the upper surface of the specimen and suspends the specimen. program.

Images