Low-gravity simulation method suitable for earth gravity environment

Abstract

The invention discloses a low-gravity simulation method suitable for an earth gravity environment. The low-gravity simulation method comprises the following steps: constructing a low-gravity simulation device; the simulation device comprises a plane, and a first inclination angle inclined plane and a second inclination angle inclined plane which are symmetrically arranged relative to the plane; the bottom end of the first dip angle slope is connected with one end of the plane through a first arc, and the bottom end of the second dip angle slope is connected with the other end of the plane through a second arc; and the movable platform is arranged on the first dip angle inclined plane, so that the movable platform slides down along the first dip angle inclined plane and sequentially passes through the first arc, the plane, the second arc and the second dip angle inclined plane, and reciprocating motion between the first dip angle inclined plane and the second dip angle inclined plane is achieved. According to the invention, the change relation of gravity along with time can be effectively simulated, and technical support is provided for a biological low-gravity simulation test.

Description

Technical Field

[0001] The present invention relates to the field of low gravity, and in particular to a low gravity simulation method adapted to the earth's gravity environment. Background Art

[0002] With the development of aerospace technology, deep space exploration of extraterrestrial bodies such as Mars and the Moon has become an important direction of human space activities. Establishing long-term workstations and bases can provide astronauts with a living environment, and the nutrients needed for astronauts can be obtained by cultivating plants in the base. Since the low-gravity environment in extraterrestrial bodies such as Mars and the Moon will have a certain impact on plant cultivation, it is necessary to simulate the low-gravity environment on the ground so that more researchers can conduct experimental verification on the ground.

[0003] At present, there are two methods to simulate micro-low gravity environment on the ground: force balance method and motion method. The force balance method adds a balancing force to the object to balance gravity, thereby offsetting the effect of gravity on the object. Methods that use the force balance method to simulate micro-low gravity include suspension method, water flotation method, air flotation method, etc. However, the force balance method cannot achieve internal balance of field forces such as gravity, and cannot eliminate the biological perception of weight, so it cannot simulate the low gravity effect of organisms.

[0004] The kinematic method is achieved by making the experimental platform and the object fall "equivalently". The organism is in motion with the object, and the weight is no longer perceived through deformation. Common methods of using the kinematic method to simulate micro-low gravity include the drop tower method, parabolic flight method, sounding rocket method, high-altitude balloon method, etc. Although the kinematic method can simulate the micro / low gravity field in the earth's environment, it is short in time, high in cost, and far from meeting the time requirements for plant growth and development.

[0005] In summary, neither the force balance method nor the motion method can simulate low-gravity and other field forces in the earth's environment. Even if long-term experiments can be carried out, the mechanical environment of the experiment is far from the real low-gravity environment. Therefore, in order to solve the above problems, a low-gravity simulation method that is adapted to the earth's gravity environment is needed, which can effectively simulate the relationship between the change of gravity and time, and provide technical support for biological low-gravity simulation experiments. Summary of the invention

[0006] In view of this, the purpose of the present invention is to overcome the defects in the prior art and provide a low-gravity simulation method adapted to the earth's gravity environment, which can effectively simulate the relationship between the change of gravity and time and provide technical support for conducting biological low-gravity simulation experiments.

[0007] The low gravity simulation method adapted to the earth's gravity environment of the present invention comprises:

[0008] Construct a low-gravity simulation device; the simulation device comprises a plane and a first inclined plane and a second inclined plane symmetrically arranged about the plane; the bottom end of the first inclined plane is connected to one end of the plane through a first circular arc, and the bottom end of the second inclined plane is connected to the other end of the plane through a second circular arc;

[0009] The mobile platform is arranged on the first inclined plane, so that the mobile platform slides down along the first inclined plane and passes through the first arc, the plane, the second arc and the second inclined plane in sequence to realize reciprocating motion between the first inclined plane and the second inclined plane.

[0010] Furthermore, the simulated gravitational acceleration g when the mobile platform slides down the slope is determined according to the formula sim :

[0011] g sim = g·cosθ;

[0012] Wherein, g is the acceleration of gravity of the earth, and θ is the angle between the first inclination slope and the plane.

[0013] Furthermore, the mobile platform is a car, and the car includes front wheels and rear wheels; the simulated gravitational acceleration g when only the front wheels of the car enter the descending stage of the arc is determined according to the following formula: sim :

[0014]

[0015] Among them, m c is the mass of the car; m cs is the mass of the car body excluding the wheels; h is the height of the car's center of mass falling; J cs is the body moment of inertia; m w is the wheel mass; J w is the wheel moment of inertia; P1=(2N1-M1) 2 cotα1+M1 2 ;

[0016] N1=(Rr)cosα1; r is the radius of the wheel; R is the radius of the arc; l is the distance between the center of mass of the front wheel and the center of mass of the rear wheel; α1 is the angle of movement of the front wheel in the arc relative to the center of the arc.

[0017] Furthermore, the mobile platform is a car, and the car includes front wheels and rear wheels; the simulated gravitational acceleration g when both the front wheels and the rear wheels of the car enter the descending stage of the arc is determined according to the following formula: sim :

[0018]

[0019] in,

[0020] Furthermore, the mobile platform is a car, and the car includes front wheels and rear wheels; the simulated gravitational acceleration g when only the rear wheels of the car enter the descending stage of the arc is determined according to the following formula: sim :

[0021]

[0022] in, K3=M3csc 2 (θ-α2);

[0023]

[0024] M3=l 2 -(Rr) 2 (1-cos(θ-α2)) 2 ; S = (Rr) sin (θ-α2); α2 is the angle of movement of the rear wheel in the arc relative to the center of the arc.

[0025] Furthermore, the gravitational acceleration g simulated when the mobile platform slides on the plane sim is the earth's gravitational acceleration g.

[0026] Furthermore, using the maximum simulated gravitational acceleration max(g sim ) and the proportion of time in the overweight state e are used as evaluation parameters for the simulation effect;

[0027] Among them, the maximum simulated gravity acceleration max(g sim ) reflects the deviation between the simulated gravity acceleration under overweight and the ideal simulated gravity acceleration. The smaller the value, the smaller the difference with the ideal value and the higher the simulation accuracy.

[0028] The proportion of time in overgravity e reflects the proportion of time that the mobile platform is not in an ideal state. The smaller the value, the greater the proportion of time that the mobile platform is in an ideal low-gravity environment, and the better the simulation effect. When the value is too large, the time in the overgravity period is too long, and the low-gravity simulation device will not be able to perform low-gravity simulation.

[0029] Furthermore, the overweight state time proportion e is the ratio of the time the mobile platform moves in the overweight section to the total movement time; wherein, the time the mobile platform moves in the overweight section is the sum of the time the mobile platform moves in the circular section and the time the mobile platform moves in the horizontal section; the total movement time is the time the mobile platform moves in the overweight section and the time the mobile platform moves in the inclined section.

[0030] The beneficial effects of the present invention are as follows: the present invention discloses a low-gravity simulation method adapted to the earth's gravity environment, which analyzes in detail the relationship between the change of simulated gravity over time under the dual-slope-horizontal state, and establishes an evaluation mechanism combining the maximum gravity acceleration with the proportion of overweight time. In view of the problem of energy loss caused by uncertain factors and friction during movement, an energy compensation method based on the ejection impact method is proposed, and the change law of the whole process simulated gravity acceleration with parameters such as initial height and arc radius is clarified. Taking the three low-gravity environment simulations of g / 2, g / 3, and g / 6 as the research objects, the speed, rising height, proportion of overweight time and gravity acceleration during the movement are comprehensively compared, and the parameter curves under different low-gravity environments before and after energy compensation are obtained, forming a parameter collaborative optimization method for the dual-slope-horizontal periodic low-gravity simulation device, which provides technical support for subsequent biological low-gravity simulation experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0032] Figure 1 is a schematic diagram of a low gravity device of the present invention;

[0033] Figure 2 This is a schematic diagram of the initial position of the inclined plane of the trolley of the present invention;

[0034] Figure 3 It is a schematic diagram of the center of mass height when the front wheel of the trolley of the present invention enters a circular arc;

[0035] Figure 4 It is a schematic diagram of the center of mass height of the two wheels of the trolley of the present invention in the arc;

[0036] Figure 5 It is a schematic diagram of the center of mass height when the front wheels of the trolley of the present invention are in an arc;

[0037] Figure 6 It is a schematic diagram of the motion relationship when the front wheels of the trolley of the present invention enter a circular arc;

[0038] Figure 7 It is a schematic diagram of the motion relationship between the two wheels of the trolley of the present invention in a circular arc;

[0039] Figure 8 It is a schematic diagram of the motion relationship when the front wheels of the trolley of the present invention move in an arc. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings, as shown in the drawings:

[0041] This embodiment discloses a low gravity simulation method adapted to the earth's gravity environment, comprising the following steps:

[0042] Construct a low-gravity simulation device; the simulation device comprises a plane and a first inclined plane and a second inclined plane symmetrically arranged about the plane; the bottom end of the first inclined plane is connected to one end of the plane through a first circular arc, and the bottom end of the second inclined plane is connected to the other end of the plane through a second circular arc;

[0043] The mobile platform is arranged on the first inclined plane, so that the mobile platform slides down along the first inclined plane and passes through the first arc, the plane, the second arc and the second inclined plane in sequence to realize reciprocating motion between the first inclined plane and the second inclined plane.

[0044] In this embodiment, the mobile platform is a small car; Figure 1 As shown in the figure, the whole device consists of two inclined planes with an inclination angle of θ and a plane with a length of L. The plane and the inclined plane are connected by a circular arc with a radius of R. The initial height from the center of mass of the car to the bottom of the inclined plane is H, and it slides freely from the inclined plane, rises to the inclined plane on the other side through the plane, and then slides down from the inclined plane on the other side to achieve periodic motion. The mass of the car is m c , the mass of the car body excluding the wheels is m cs , the height of the car's center of mass is h c , the height of the vehicle center of mass is h cs The car is a four-wheeled car with a wheel radius of r. The distance between the center of mass of the car and the center of the front wheel in the direction of the slope is b.

[0045] The motion process of the car is divided into the inclined plane sliding stage (AB segment), the two-segment circular arc transition stage (BF segment), the plane rolling stage (FG segment), and the inclined plane rising stage (GH segment). Assuming that the car is pure rolling during the motion process and there is no energy loss, the car is completely symmetrical in the sliding and rising stages, so only the inclined plane sliding stage (AB segment), the circular arc transition stage (BF segment) and the plane motion stage (FG segment) of the car are considered.

[0046] Downward phase (AB segment):

[0047] like Figure 2 As shown in the figure, the car sliding down the inclined plane is a uniformly accelerated motion. The acceleration of the car is a = gsinθ, and the speed is v = gsinθ·t. The simulated gravitational acceleration is:

[0048]

[0049] i.e. g sim =g·cosθ. The running time of this stage

[0050] Arc transition stage (BF segment):

[0051] like Figure 2As shown, let the center of the arc be O. When the car is at the initial height, let the center of the front wheel be O1, the center of the rear wheel be O2, and the center of mass of the car be C. m , the center of mass of the vehicle body is C ms .

[0052] At this time, take O as the origin, the horizontal right direction as the x-axis, and the vertical upward direction as the y-axis to establish a plane rectangular coordinate system O. xy . Then the vertical coordinate of the center of mass of the car is:

[0053] C my =H+(h c -R)cosθ (2)

[0054] Front wheel arc descending stage (BD segment):

[0055] like Figure 3 As shown, let the center of the front wheel of the car be O'1, the center of the rear wheel be O'2, and the center of mass of the car be C' m , the center of mass of the vehicle body is C' ms The angle at which the current wheel moves in the arc relative to the origin O When the front wheel of the car enters the arc, the rear wheel is still on the inclined plane. With O as the origin, the downward direction parallel to the inclined plane as the u axis, and the upward direction perpendicular to the inclined plane as the v axis, establish a plane rectangular coordinate system O uv .

[0056] At this time, the center coordinates of the front wheel of the car are O'1((Rr)·sinα1,-(Rr)·cosα1), and the center coordinates of the rear wheel are O'2(O' 2u ,-(Rr)), where

[0057] have to

[0058] The acute angle between the line connecting the two wheels and the u-axis is:

[0059]

[0060] Coordinates of the midpoint of the line connecting the two wheel centers:

[0061]

[0062] Therefore, the center of mass of the car is O uv The coordinates in the coordinate system are:

[0063]

[0064] in

[0065] The center of mass of the car is at O xyThe coordinates in the coordinate system are:

[0066]

[0067] At this time, the height of the car's center of mass dropping is:

[0068]

[0069] in

[0070] Two-round arc descent stage (DE segment):

[0071] like Figure 4 As shown, the angle that the current wheel moves in the arc relative to the origin O is:

[0072] When , both the front and rear wheels are located in the arc, the angle of the rear wheel in the arc relative to the origin O is: Among them, the angle between the center of the front and rear wheels and the line connecting the origin

[0073] In the coordinate system Oxy, the center coordinates of the front wheels of the car are O'1(-(Rr)sin(θ-α1),-(Rr)cos(θ-α1)), and the center coordinates of the rear wheels are O'2(-(Rr)sin(θ-α1+θ2),-(Rr)cos(θ-α1+θ2)).

[0074] The acute angle between the line connecting the two wheels and the horizontal direction is:

[0075]

[0076] Coordinates of the midpoint of the line connecting the two wheel centers:

[0077]

[0078] The vertical coordinate of the center of mass of the car is obtained as follows:

[0079]

[0080] in

[0081] At this time, the height of the car's center of mass dropping is:

[0082]

[0083] Rear wheel arc descending stage (EF segment):

[0084] like Figure 5 As shown, the angle of movement of the rear wheel in the arc relative to the origin O is:

[0085] , the front wheels have moved out of the arc and entered the plane, while the rear wheels continue to slide down in the arc section.

[0086] In the coordinate system O xy The center coordinate of the front wheel of the car is O'1(O' 1x ,-(Rr)), the rear wheel center coordinate O'2(-(Rr)sin(θ-α2),-(Rr)cos(θ-α2)), where

[0087]

[0088] Solved

[0089] The acute angle between the center line of the two wheels and the horizontal direction is:

[0090]

[0091] Coordinates of the midpoint of the line connecting the two wheel centers:

[0092]

[0093] The vertical coordinate of the center of mass of the car is obtained as follows:

[0094]

[0095] Where M3 = l 2 -(Rr) 2 (1-cos(θ-α2)) 2 .

[0096] At this time, the height of the car's center of mass dropping is:

[0097]

[0098] Based on the above analysis, the simulated gravity acceleration of the vehicle body is further analyzed as follows:

[0099] The vehicle body speed is obtained by the kinetic energy theorem, and the formula is as follows:

[0100]

[0101] Among them, J cs is the body moment of inertia, m w is the wheel mass, J w is the wheel moment of inertia, v and ω are the vehicle body speed and angular velocity respectively, v1 and ω1 are the front wheel speed and angular velocity respectively, and v2 and ω2 are the rear wheel speed and angular velocity respectively.

[0102] There is the following relationship:

[0103]

[0104] Where P is the instantaneous center of the car's velocity, C' ms is the center of mass of the vehicle body. Substituting the above formula into (17), we get

[0105]

[0106] The following will discuss this in stages.

[0107] Front wheel arc descending stage (BD segment):

[0108] like Figure 6 As shown in (a), P is the instantaneous center of the car's velocity, which is in the coordinate system O uv The coordinates P(P u ,P v ),in

[0109]

[0110] Solved

[0111] Distance between instant center and front wheel center:

[0112]

[0113] Distance between instant center and rear wheel center:

[0114]

[0115] Car body center of mass coordinates:

[0116]

[0117] The distance between the center of mass of the vehicle body and the instantaneous center is:

[0118]

[0119] in N1=(Rr)cosα1.

[0120] According to formula (19), the body speed of the car is:

[0121]

[0122] The expression of h is shown in formula (7).

[0123] like Figure 6 As shown in (b), when the front wheel passes dt, the angle the front wheel passes relative to the origin O is dα1, then:

[0124] v1·dt=(Rr)·dα1 (26)

[0125] Will Substituting in and integrating both sides, we get the running time of this stage:

[0126]

[0127] The acceleration of the vehicle body is:

[0128]

[0129] in

[0130]

[0131] The simulated gravitational acceleration is:

[0132]

[0133] Two-round arc descent stage (DE segment):

[0134] like Figure 7 As shown, at this stage, the instantaneous center P coincides with the arc center O, so the distance from P to O'1 and O'2 is equal, that is,

[0135] |PO'1|=|PO'2|=Rr (30)

[0136] The distance from the instantaneous center to the center of mass of the vehicle body is:

[0137]

[0138] Substituting into equation (19), we can get the speed of the car body at this stage:

[0139]

[0140] The expression of h is shown in formula (11).

[0141] The running time of this stage is the same as formula (26), that is:

[0142]

[0143] According to equations (26) and (32), the vehicle body acceleration can be obtained as:

[0144]

[0145] in The simulated gravitational acceleration is:

[0146]

[0147] Rear wheel arc descending stage (EF segment):

[0148] like Figure 8(a) shows that the coordinates of the instantaneous center P are (O' 1x ,P y ), where the slope of the straight line PO'2 is:

[0149]

[0150] Solved Distance between instant center and front wheel center:

[0151]

[0152] Distance between instant center and rear wheel center:

[0153]

[0154] Car body center of mass coordinates:

[0155]

[0156] The distance between the center of mass of the vehicle body and the instantaneous center is:

[0157]

[0158] Where M3 = l 2 -(Rr) 2 (1-cos(θ-α2)) 2 , S = (Rr) sin (θ-α2).

[0159] Substituting into equation (19), we can get the speed of the car body at this stage:

[0160]

[0161] The expression of h is shown in formula (16).

[0162] like Figure 8 As shown in (b), when the rear wheel passes dt, the angle the rear wheel passes relative to the origin O is dα2, then:

[0163] v2@dt=(Rr)·dα2 (42)

[0164] The running time of this stage is:

[0165]

[0166] The vehicle body acceleration is:

[0167]

[0168] in,

[0169]

[0170] K3=M3 csc 2 (θ-α2)

[0171]

[0172] The simulated gravitational acceleration is:

[0173]

[0174] Planar motion stage (FG segment):

[0175] like Figure 1 As shown in the figure, after the car leaves the arc, without considering the energy loss, the car moves at a uniform speed on the plane. According to formula (17), the speed of the car is:

[0176] v=2g[H+(h c -R)(1+cosθ)] (46)

[0177] The gravitational acceleration simulated by the car is g. The running time of this stage is:

[0178]

[0179] In this embodiment, the present invention uses the maximum simulated gravity acceleration max (g sim ) and the proportion of overweight state time e are used as evaluation parameters of simulation effect.

[0180] (1) Maximum simulated gravitational acceleration max(g sim ): Maximum simulated gravity acceleration refers to the simulated gravity acceleration g on the mobile platform when it is in the overweight section. sim This evaluation parameter reflects the degree of deviation between the simulated gravity acceleration in overweight and the ideal simulated gravity acceleration. The smaller the value, the smaller the difference with the ideal value and the higher the simulation accuracy.

[0181] (2) Proportion of time in overweight state e: The sum of the time 2 (t2+t3+t4) that the mobile platform moves in the circular segment and the time t5 that the mobile platform moves in the horizontal segment is the time that the mobile platform moves in the overweight segment. During this time, the mobile platform is always in the overweight state. The ratio of this time to the total time is e, that is:

[0182]

[0183] This evaluation parameter reflects the proportion of time that the mobile platform is not in an ideal state. The smaller the value, the greater the proportion of time that the mobile platform is in an ideal low-gravity environment, and the better the simulation effect. When the value is too large, the time in the overgravity period is too long and the device will not be able to perform low-gravity simulation.

[0184] Therefore, during the entire motion process, the ratio of the overweight state time to the total time is:

[0185]

[0186] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A low gravity simulation method adapted to the earth's gravity environment, characterized in that: include: Building a low-gravity simulation device; The simulation device comprises a plane and a first inclined plane and a second inclined plane symmetrically arranged with respect to the plane; The bottom end of the first inclined surface is connected to one end of the plane through a first arc, and the bottom end of the second inclined surface is connected to the other end of the plane through a second arc; The mobile platform is arranged on the first inclined plane, so that the mobile platform slides down along the first inclined plane and passes through the first arc, the plane, the second arc and the second inclined plane in sequence to realize reciprocating motion between the first inclined plane and the second inclined plane.

2. The low gravity simulation method adapted to the earth's gravity environment according to claim 1, characterized in that: Determine the gravitational acceleration g simulated when the mobile platform slides down the slope according to the formula sim : g sim =g·cosθ; Wherein, g is the acceleration of gravity of the earth, and θ is the angle between the first inclination slope and the plane.

3. The low gravity simulation method adapted to the earth's gravity environment according to claim 1, characterized in that: The mobile platform is a car, and the car includes front wheels and rear wheels. The simulated gravitational acceleration g when only the front wheels of the car enter the descending stage of the arc is determined according to the following formula: sim : Among them, m c is the mass of the car; m cs is the mass of the car body excluding the wheels; h is the height of the car's center of mass falling; J cs is the body moment of inertia; m w is the wheel mass; J w is the wheel moment of inertia; P1=(2N1-M1) 2 cotα1+M1 2 ; N1=(Rr)cosα1; r is the wheel The radius of the arc; R is the radius of the arc; l is the distance between the center of mass of the front wheel and the center of mass of the rear wheel; α1 is the angle of movement of the front wheel in the arc relative to the center of the arc.

4. The low gravity simulation method adapted to the earth's gravity environment according to claim 1, characterized in that: The mobile platform is a car, and the car includes front wheels and rear wheels. The simulated gravitational acceleration g when both the front wheels and the rear wheels of the car enter the descending stage of the arc is determined according to the following formula: sim : in, 5. The low gravity simulation method adapted to the earth's gravity environment according to claim 1, characterized in that: The mobile platform is a car, and the car includes front wheels and rear wheels. The simulated gravitational acceleration g when only the rear wheels of the car enter the descending stage of the arc is determined according to the following formula: sim : in, K3=M3csc 2 (θ-α2); M3=1 2 -(Rr) 2 (1-cos(θ-α2)) 2 ; S = (Rr) sin (θ-α2); α2 is the angle of movement of the rear wheel in the arc relative to the center of the arc.

6. The low gravity simulation method adapted to the earth's gravity environment according to claim 1, characterized in that: The gravitational acceleration g simulated when the mobile platform slides on the plane sim is the earth's gravitational acceleration g.

7. The low gravity simulation method adapted to the earth's gravity environment according to claim 1, characterized in that: Using the maximum simulated gravitational acceleration max(g sim ) and the proportion of time in the overweight state e are used as evaluation parameters for the simulation effect; Among them, the maximum simulated gravity acceleration max(g sim ) reflects the deviation between the simulated gravity acceleration under overweight and the ideal simulated gravity acceleration. The smaller the value, the smaller the difference with the ideal value and the higher the simulation accuracy. The proportion of time in overgravity e reflects the proportion of time that the mobile platform is not in an ideal state. The smaller the value, the greater the proportion of time that the mobile platform is in an ideal low-gravity environment, and the better the simulation effect. When the value is too large, the time in the overgravity period is too long, and the low-gravity simulation device will not be able to perform low-gravity simulation.

8. The low gravity simulation method adapted to the earth's gravity environment according to claim 7, characterized in that: The overweight state time proportion e is the ratio of the time the mobile platform moves in the overweight section to the total movement time; wherein, the time the mobile platform moves in the overweight section is the sum of the time the mobile platform moves in the circular section and the time the mobile platform moves in the horizontal section; the total movement time is the time the mobile platform moves in the overweight section and the time the mobile platform moves in the inclined section.

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