Leg type robot landing stability test system for simulating thrust plume aftereffect

Abstract

The invention discloses a legged robot landing stability test system for simulating thrust plume aftereffect, is used for evaluating and verifying the buffer stability performance influenced by the plume aftereffect in the landing process of a legged robot, and belongs to the technical field of robot design verification. Through flexible combination of the inclined air floating plane, the landing surface, the horizontal speed raising device, the constant force device and the three-degree-of-freedom ball bearing, the problems that a traditional landing stability test is large in site requirement, large in environmental influence and only capable of simulating fixed acceleration are solved; it is ensured that the thrust plume aftereffect and the long-stroke low-gravity environment influence can be simulated with high precision, and landing stability tests of the legged robot are supported to be carried out.

Description

Technical Field

[0001] This invention relates to a landing stability test system for legged robots that simulates the aftereffects of thrust plumes. It is used to evaluate and verify the buffer stability performance of legged robots affected by plume aftereffects during landing and belongs to the field of robot design verification technology. Background Technology

[0002] In the aerospace field, stability during spacecraft landing is one of the key factors in ensuring a safe landing. However, with the continuous development of aerospace technology, especially the deepening research on reusable landing mechanisms such as legged robots, these mechanisms are characterized by repeatability, relatively weak buffering capacity, long buffering stroke, and significant impact from thrust plume aftereffects (i.e., the influence of high-speed gas flow generated by engine thrust on the surrounding environment).

[0003] Traditional spacecraft landing buffer tests typically involve slinging the spacecraft and impacting it onto a tilted landing surface at a certain angle to the ground plane. This allows for the acquisition of the low-gravity component vertically to the tilted landing surface at the moment of impact, simulating the forces acting on the spacecraft in a low-gravity environment. However, the landing surface tilt angle is fixed and cannot be adjusted; only the acceleration at the moment of impact is accurate, while accelerations at other times are inaccurate; and the test site requires significant resources, often located in outdoor areas and subject to considerable constraints from the natural environment.

[0004] Legged robots have weaker landing performance than cellular landing legs and require a longer landing buffer stroke. Therefore, the auxiliary impact of thrust plume aftereffects on the landing stability of legged robots must be fully considered in experiments, and the duration of low gravity must be extended to avoid damage to the legged robot due to overload during the experiment, and also to avoid significant deviations between the experimental results and actual on-orbit landing conditions. However, traditional spacecraft landing stability testing methods, due to their fixed acceleration design on the landing surface, have short durations of low gravity, and are costly and time-consuming to modify, making them unable to meet this requirement. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a test system for the landing stability of legged robots that simulates the aftereffect of thrust plume. This system solves the problem that traditional test methods fail to fully consider the impact of thrust plume aftereffect and short stroke under low gravity on the stability of the lander, and enables a more realistic, convenient and quick evaluation of the landing stability performance of legged robots under the influence of thrust plume aftereffect.

[0006] The technical solution of the present invention is: Firstly, a test system for simulating the aftereffects of a thrust plume on the landing stability of a legged robot, comprising:

[0007] The tilted air-floating plane is fixed to the ground. By continuously adjusting the tilt angle, the equivalent simulation of the thrust plume aftereffect of the legged robot and the construction of a long-stroke low-gravity acceleration environment can be achieved.

[0008] A constant force device, installed on the inclined air-float plane, is used to provide a constant support force for the legged robot, enabling it to passively follow the movement of the center of mass of the legged robot body.

[0009] A three-degree-of-freedom ball bearing is installed at the connection between the constant force device and the legged robot. It converts the connection between the legged robot and the constant force device into a ball joint through air flotation, enabling the legged robot to change its posture in any direction.

[0010] The simulated landing surface is installed at the expected landing position of the legged robot, and its tilt angle can be continuously adjusted to simulate the landing terrain slope.

[0011] The horizontal acceleration device is installed on the constant force device and is used to drive the constant force device and the legged robot to move to reach the predetermined landing horizontal speed.

[0012] The legged robot is mounted on a three-degree-of-freedom ball bearing and supported by a constant force device and the three-degree-of-freedom ball bearing. It can achieve six-degree-of-freedom free movement on an inclined air-float plane. The vertical velocity of landing is simulated by the free fall height along the inclined air-float plane, the horizontal velocity of landing is simulated by the horizontal acceleration device, and the parameters including the landing slope angle and friction coefficient are simulated by simulating the landing surface.

[0013] Furthermore, the average thrust after the plume of the power generation during the landing process of the legged robot is... Where m is the spacecraft mass, a and b are control system constants, v0 is the spacecraft velocity at the moment of contact with the ground, v is the actual velocity of the spacecraft, t is the landing time, and T is the total landing time.

[0014] Furthermore, the tilt angle of the tilted air-float plane is θ = arcsin(g simu / g earth ); where g simu For the gravitational acceleration of the landing planet's environment, g earth This refers to the acceleration due to Earth's gravity.

[0015] Furthermore, the six degrees of freedom of the legged robot are released during the landing buffer process by using an inclined air-floating platform, a constant force mechanism, and air-floating ball bearings. Taking into account the thrust plume aftereffect and the requirements of the low gravity environment, the tilt angle of the inclined air-floating platform is calculated by the average thrust of the thrust plume aftereffect. The initial landing conditions are simulated by the free fall height and the horizontal acceleration device.

[0016] Furthermore, during the landing buffering process of the legged robot, there is always an aftereffect of the thrust plume, resulting in an average thrust. The equivalent environmental acceleration under the influence is Where g lowG =g earth ×sin(θ) represents the gravitational acceleration of the experimental system in the low-gravity environment, g earth θ represents the Earth's gravitational acceleration, and θ represents the tilt angle of the experimental system's tilted plane. The mean thrust after the thrust plume.

[0017] Furthermore, the vertical landing velocity of the legged robot is simulated and controlled by the free fall height, which is H = v0. 2 / 2g simu Where v0 represents the vertical landing velocity to be achieved, and g simu This represents the equivalent environmental acceleration considering the aftereffects of the thrust plume.

[0018] Secondly, a method for testing the landing stability of a legged robot using the aforementioned test system for simulating the aftereffects of a thrust plume includes:

[0019] Based on the basic parameters of the engine thrust plume aftereffect and the basic parameters of the landing buffer process, the average thrust of the engine thrust plume aftereffect during landing is calculated.

[0020] Based on the acceleration g of the celestial surface environment lowG and engine thrust plume aftereffect average thrust The equivalent environmental acceleration g that needs to be simulated during the landing process simu ;

[0021] The six degrees of freedom of the legged robot are released during the landing buffer process by using an inclined air-floating platform, a constant force mechanism and air-floating ball bearings. Taking into account the thrust plume aftereffect and the requirements of the low gravity environment, the tilt angle of the inclined air-floating platform is calculated by the average thrust of the thrust plume aftereffect, and the tilt angle of the air-floating platform of the test system is set according to this result.

[0022] The landing assembly, consisting of a constant force mechanism, air-bearing ball bearings, and a legged robot, serves as the main landing buffer and is placed on the inclined plane of the air-bearing platform. The simulated landing surface is set perpendicular to the inclined plane of the air-bearing platform and serves as a simulated star surface to support the landing assembly.

[0023] Based on the velocity v0 at the moment of ground contact and the equivalent environmental acceleration g simu Calculate the free fall height H; and determine the fall height of the landing assembly based on this result.

[0024] The landing horizontal speed is set via the horizontal acceleration device;

[0025] At the start of the test, the horizontal acceleration device drives the landing assembly to begin sliding on the inclined plane of the air-floating platform. Once the speed reaches the required horizontal landing speed, the horizontal acceleration device separates from the landing assembly. The landing assembly then undergoes free fall along the inclined plane while moving horizontally, and finally the legged robot lands on the simulated landing surface.

[0026] Furthermore, according to claim 1, the landing stability test system for a legged robot simulating the aftereffects of a thrust plume is characterized in that the basic parameters of the landing buffer process include the spacecraft mass m, the velocity v0 at the moment of contact with the ground, the actual velocity v0 of the spacecraft, the landing time t, and the total landing time T.

[0027] Furthermore, the average thrust after the plume of the power generation during the landing process of the legged robot is... Where m is the spacecraft mass, a and b are control system constants, v0 is the spacecraft velocity at the moment of contact with the ground, v is the actual velocity of the spacecraft, t is the landing time, and T is the total landing time.

[0028] Furthermore, the tilt angle of the tilted air-float plane is θ = arcsin(g simu / g earth ); where g simu For the gravitational acceleration of the landing planet's environment, g earth This refers to the acceleration due to Earth's gravity.

[0029] The advantages of this invention compared to the prior art are:

[0030] (1) This invention solves the problems of thrust plume aftereffect equivalent simulation and long-stroke low-gravity environment construction by using an inclined air-float plane with continuously adjustable tilt angle;

[0031] (2) This invention solves the problem of rapid simulation of initial landing conditions by using free fall height control and horizontal acceleration device;

[0032] (3) This invention solves the problems of traditional landing stability testing, which requires a large site, is greatly affected by the environment, and can only simulate fixed acceleration, by flexibly combining the inclined air-floating plane, landing surface, horizontal acceleration device, constant force device and three-degree-of-freedom ball bearing. It ensures that the aftereffects of thrust plume and the influence of long-stroke low-gravity environment can be simulated with high precision, and supports the implementation of landing stability tests for legged robots. Attached Figure Description

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0034] Figure 1 A side view of the overall status of the landing stability test system platform;

[0035] Figure 2 A top view of the overall status of the landing stability test system platform;

[0036] Figure 3 Schematic diagram of a zero-stiffness constant force mechanism and an air-bearing ball bearing;

[0037] Figure 4 This is a schematic diagram of a comprehensive system for testing the landing stability of a legged robot. Detailed Implementation

[0038] To better understand the above technical solutions, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of the present invention, rather than limitations on the technical solutions of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0039] The following description, in conjunction with the accompanying drawings, provides a more detailed explanation of the landing stability test system for a legged robot simulating the aftereffects of a thrust plume, as provided in the embodiments of the present invention. Specific implementation methods may include:

[0040] The tilted air-floating plane is fixed to the ground. By continuously adjusting the tilt angle, the equivalent simulation of the thrust plume aftereffect of the legged robot and the construction of a long-stroke low-gravity acceleration environment can be achieved.

[0041] A constant force device, installed on the inclined air-float plane, is used to provide a constant support force for the legged robot, enabling it to passively follow the movement of the center of mass of the legged robot body.

[0042] A three-degree-of-freedom ball bearing is installed at the connection between the constant force device and the legged robot. It converts the connection between the legged robot and the constant force device into a ball joint through air flotation, enabling the legged robot to change its posture in any direction.

[0043] The simulated landing surface is installed at the expected landing position of the legged robot, and its tilt angle can be continuously adjusted to simulate the landing terrain slope.

[0044] The horizontal acceleration device is installed on the constant force device and is used to drive the constant force device and the legged robot to move to reach the predetermined landing horizontal speed.

[0045] The legged robot is mounted on a three-degree-of-freedom ball bearing and supported by a constant force device and the three-degree-of-freedom ball bearing. It can achieve six-degree-of-freedom free movement on an inclined air-float plane. The vertical velocity of landing is simulated by the free fall height along the inclined air-float plane, the horizontal velocity of landing is simulated by the horizontal acceleration device, and the parameters including the landing slope angle and friction coefficient are simulated by simulating the landing surface.

[0046] In the embodiment of this invention, the test platform comprises an inclined air-floating plane, a constant force device, a three-degree-of-freedom ball bearing, a simulated landing surface, and a legged robot for testing. The inclined air-floating plane is designed with a continuously adjustable tilt angle. Through continuous adjustment of the tilt angle, the equivalent simulation of the thrust plume aftereffect and the construction of a long-stroke, low-gravity acceleration environment are achieved. The legged robot, supported by the constant force device and the three-degree-of-freedom ball bearing, achieves six-degree-of-freedom free movement on the inclined air-floating plane. The vertical landing velocity is simulated by the free fall height along the inclined plane, and the horizontal landing velocity is simulated by the horizontal acceleration device. The simulated landing surface, with its continuously adjustable tilt angle, simulates the landing slope angle, friction coefficient, etc.

[0047] Specifically, it includes:

[0048] (1) Design of six-degree-of-freedom test states for legged robots

[0049] The landing process of legged robots differs significantly from that of traditional cellular landing robots, specifically in the substantial changes in the spacecraft's center of mass displacement and attitude. Therefore, the experimental simulation requires the release of six degrees of freedom. The air-bearing plane releases two translational degrees of freedom within the plane, so one vertical degree of freedom and three rotational degrees of freedom also need to be released.

[0050] The vertical degree of freedom is achieved through a constant force mechanism, such as... Figure 3 As shown, the constant force mechanism provides a constant supporting force, enabling it to passively follow the movement of the legged robot's center of mass, which manifests as a "zero stiffness" system in physical phenomena.

[0051] The three rotational degrees of freedom are achieved through air-bearing ball bearings. The air-bearing mechanism converts the legged robot and the constant force mechanism into ball joints, enabling the legged robot to change its posture in any direction.

[0052] (2) Equivalent simulation of thrust plume aftereffect

[0053] Thrust plume aftereffects refer to the impact of the high-velocity gas flow generated by engine thrust on the surrounding environment. In the spacecraft field, a hit-and-go shutdown strategy is often adopted to increase reliability. Therefore, during the landing phase, the thrust plume aftereffects will have a significant impact on the landing stability of legged robots.

[0054] During the spacecraft engine landing phase, thrust is controlled according to the equivalent net thrust F.

[0055] F=m[-a(v0+v)+b] (1)

[0056] Where m represents the spacecraft mass, a and b are control system constants, v0 represents the velocity at the moment of ground contact, and v represents the actual velocity of the spacecraft.

[0057] Therefore, based on numerical simulation analysis of the spacecraft landing process, the momentum change ΔP of the spacecraft during the thrust aftereffect can be obtained as shown in the following equation. t represents the landing time.

[0058]

[0059] Simultaneously, according to the definition of momentum change, the impulse of a force is the average force per unit time. Multiply by the total landing time T, that is:

[0060]

[0061] Therefore, the mean thrust after the engine thrust plume during the landing process can be obtained as follows:

[0062]

[0063] Based on the above analysis, the equivalent simulation of the thrust plume aftereffect during the spacecraft landing phase requires obtaining the average thrust of the thrust plume aftereffect based on the numerical simulation of the landing process, and then simulating this average thrust in the experiment.

[0064] (3) Construction of low gravity environment

[0065] The tilting air-floating platform can achieve gravitational acceleration g in low-gravity environments. lowG (This is related to the gravitational environment of the planet where the spacecraft needs to land; for example, for lunar landing, the g value is...) earth / 6) Related to the tilt angle θ, calculated as follows:

[0066] g lowG =g earth ×sin(θ) (5)

[0067] In the formula, g earth g represents the acceleration due to gravity on the ground. earth =9.81m / s 2 .

[0068] This formula allows for the convenient calculation of the tilt angle setting value of the tilted air-bearing platform in the required low-gravity acceleration environment.

[0069] Considering the aftereffect of the engine thrust plume, i.e., during the landing buffering process of the legged robot, there is always an average thrust due to the aftereffect of the thrust plume. The effect is the equivalent environmental acceleration g. simu The calculation can be performed as follows:

[0070]

[0071] Therefore, the tilt angle of the air-floating platform can be calculated using the following formula, which takes into account both...

[0072] θ = arcsin(g simu / g earth (7)

[0073] (4) Comprehensive landing stability test plan

[0074] In the aforementioned work, the six degrees of freedom of the legged robot during the landing buffer process were released through a tilted air-floating platform, a constant force mechanism, and air-floating ball bearings. The tilt angle of the tilted air-floating platform was calculated by the average thrust after the thrust plume effect (taking into account both the thrust plume aftereffect and the requirements of the low gravity environment). The simulation of the initial landing conditions relied on the free fall height and the horizontal acceleration device.

[0075] a) Simulate landing vertical velocity using free fall altitude

[0076] Based on kinematic formulas, high-precision simulation of the ground contact velocity can be achieved by controlling the free fall height, such as... Figure 2 As shown.

[0077]

[0078] b) Simulate landing horizontal speed using a horizontal acceleration device

[0079] The legged robot is connected to a horizontal accelerator. The horizontal accelerator drives the legged robot to move and reach the predetermined landing horizontal speed. Generally, maintaining this speed for a period of time after reaching the landing horizontal speed helps stabilize the legged robot's horizontal velocity. Figure 1 As shown.

[0080] According to the above control scheme, the legged robot will complete the landing buffer on the landing surface according to the predetermined vertical and horizontal velocities, taking into account the thrust plume aftereffects, in an environment where the thrust plume aftereffects are taken into account, thus fully verifying the landing stability. Figure 4As shown. Due to the high acceleration of free fall, large or even ultra-large test systems are not required, which can effectively control test specifications and accelerate the test cycle.

[0081] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations of this invention fall within the scope of the claims of this invention...

[0082] Within the scope of its equivalent technology, this invention also intends to include these modifications and variations.

[0083] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A test system for simulating the aftereffects of a thrust plume on the landing stability of a legged robot, characterized in that, include: The tilted air-floating plane is fixed to the ground. By continuously adjusting the tilt angle, the equivalent simulation of the thrust plume aftereffect of the legged robot and the construction of a long-stroke low-gravity acceleration environment can be achieved. A constant force device, installed on the inclined air-float plane, is used to provide a constant support force for the legged robot, enabling it to passively follow the movement of the center of mass of the legged robot body. A three-degree-of-freedom ball bearing is installed at the connection between the constant force device and the legged robot. It converts the connection between the legged robot and the constant force device into a ball joint through air flotation, enabling the legged robot to change its posture in any direction. The simulated landing surface is installed at the expected landing position of the legged robot, and its tilt angle can be continuously adjusted to simulate the landing terrain slope. The horizontal acceleration device is installed on the constant force device and is used to drive the constant force device and the legged robot to move to reach the predetermined landing horizontal speed. The legged robot is mounted on a three-degree-of-freedom ball bearing and supported by a constant force device and the three-degree-of-freedom ball bearing. It can achieve six-degree-of-freedom free movement on an inclined air-float plane. The vertical velocity of landing is simulated by the free fall height along the inclined air-float plane, the horizontal velocity of landing is simulated by the horizontal acceleration device, and the parameters including the landing slope angle and friction coefficient are simulated by simulating the landing surface.

2. The landing stability test system for a legged robot simulating the aftereffects of a thrust plume according to claim 1, characterized in that, The legged robot's landing process generates a thrust plume aftereffect average thrust of the generated thrust. Where m is the spacecraft mass, a and b are control system constants, v0 is the spacecraft velocity at the moment of contact with the ground, v is the actual velocity of the spacecraft, t is the landing time, and T is the total landing time.

3. The landing stability test system for a legged robot simulating the aftereffects of a thrust plume according to claim 2, characterized in that, The tilt angle of the tilted air-float plane is θ = arcsin(g simu / g earth ); where g simu For the gravitational acceleration of the landing planet's environment, g earth This refers to the acceleration due to Earth's gravity.

4. The landing stability test system for a legged robot simulating the aftereffects of a thrust plume according to claim 2, characterized in that, The landing buffer process of the legged robot is achieved by using an inclined air-floating platform, a constant force mechanism, and air-floating ball bearings to release six degrees of freedom. Taking into account the thrust plume aftereffect and the requirements of low gravity environment, the tilt angle of the inclined air-floating platform is obtained by calculating the average thrust of the thrust plume aftereffect. The initial landing conditions are simulated by the free fall height and the horizontal acceleration device.

5. The landing stability test system for a legged robot simulating the aftereffects of a thrust plume according to claim 4, characterized in that, During the landing cushioning process of the legged robot, there is always an aftereffect of the thrust plume and the average thrust. The equivalent environmental acceleration under the influence is Where g lowG =g earth ×sin(θ) represents the gravitational acceleration of the experimental system in the low-gravity environment, g earth θ represents the Earth's gravitational acceleration, and θ represents the tilt angle of the experimental system's tilted plane. The mean thrust after the thrust plume.

6. The landing stability test system for a legged robot simulating the aftereffects of a thrust plume according to claim 5, characterized in that, The vertical landing velocity of the legged robot is simulated and controlled by the free fall height, which is H = v0. 2 / 2g simu Where v0 represents the vertical landing velocity to be achieved, and g simu This represents the equivalent environmental acceleration considering the aftereffects of the thrust plume.

7. A method for testing the landing stability of a legged robot using a landing stability test system for simulating thrust plume aftereffects as described in claim 1, characterized in that, include: Based on the basic parameters of the engine thrust plume aftereffect and the basic parameters of the landing buffer process, the average thrust of the engine thrust plume aftereffect during landing is calculated. Based on the acceleration g of the celestial surface environment lowG and engine thrust plume aftereffect average thrust The equivalent environmental acceleration g that needs to be simulated during the landing process simu ; The six degrees of freedom of the legged robot are released during the landing buffer process by using an inclined air-floating platform, a constant force mechanism and air-floating ball bearings. Taking into account the thrust plume aftereffect and the requirements of the low gravity environment, the tilt angle of the inclined air-floating platform is calculated by the average thrust of the thrust plume aftereffect, and the tilt angle of the air-floating platform of the test system is set according to this result. The landing assembly, consisting of a constant force mechanism, air-bearing ball bearings, and a legged robot, serves as the main landing buffer and is placed on the inclined plane of the air-bearing platform. The simulated landing surface is set perpendicular to the inclined plane of the air-bearing platform and serves as a simulated star surface to support the landing assembly. Based on the velocity v0 at the moment of ground contact and the equivalent environmental acceleration g simu Calculate the free fall height H; and determine the fall height of the landing assembly based on this result. The landing horizontal speed is set via the horizontal acceleration device; At the start of the test, the horizontal acceleration device drives the landing assembly to begin sliding on the inclined plane of the air-floating platform. Once the speed reaches the required horizontal landing speed, the horizontal acceleration device separates from the landing assembly. The landing assembly then undergoes free fall along the inclined plane while moving horizontally, and finally the legged robot lands on the simulated landing surface.

8. The method according to claim 7, characterized in that, According to claim 1, a legged robot landing stability test system simulating the aftereffect of thrust plume is characterized in that the basic parameters of the landing buffer process include spacecraft mass m, velocity v0 at the moment of contact with the ground, actual velocity v0 of the spacecraft, landing time t, and total landing time T.

9. The method according to claim 7, characterized in that, The legged robot's landing process generates a thrust plume aftereffect average thrust of the generated thrust. Where m is the spacecraft mass, a and b are control system constants, v0 is the spacecraft velocity at the moment of contact with the ground, v is the actual velocity of the spacecraft, t is the landing time, and T is the total landing time.

10. The method according to claim 7, characterized in that, The tilt angle of the tilted air-float plane is θ = arcsin(g simu / g earth ); where g simu For the gravitational acceleration of the landing planet's environment, g earth This refers to the acceleration due to Earth's gravity.

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