A method for controlling the planetary gravitational acceleration

Abstract

The application belongs to the technical field of aerospace, and provides a control method of planetary gravitational acceleration, which is applied to a gravity drop tower device, and comprises a guide rail module, an experimental drop cabin module, a connecting module, a counterweight and a control module of gravitational acceleration. The guide rail module comprises at least two guide rails arranged along the direction of gravity. The connecting module is arranged at the other end of the guide rail module away from the ground. The experimental drop cabin module comprises an experimental drop cabin and a motor. The control module controls the acceleration of the experimental drop cabin to be a constant planetary gravitational acceleration by driving the motor. The connecting module connects the experimental drop cabin and the counterweight. The minimum value of the objective function is determined based on the error of the state variables, the control variables and the target trajectory by converting the dynamic equation of the experimental drop cabin into a spatial state equation. The control law equation is determined based on the corresponding control variables. Finally, the planetary gravitational acceleration of the experimental drop cabin is controlled based on the constraint condition and the control law equation, so that the control method is simplified and the test cost is reduced.

Description

Technical Field

[0001] This application belongs to the field of aerospace technology, and in particular relates to a method for controlling planetary gravitational acceleration. Background Technology

[0002] Currently, there are various experimental methods for simulating planetary gravity space environments, including ground-based micro / low gravity drop towers, weightless aircraft in parabolic flight, microgravity experimental rockets, microgravity experimental satellites, and space stations. These facilities can all put objects in a state of complete or partial weightlessness.

[0003] However, existing gravity experiment platforms have numerous components, complex structures, and very high equipment and maintenance costs. Correspondingly, the control methods are also highly complex. Furthermore, existing technologies mainly simulate partial weightlessness of objects in various planetary gravity environments.

[0004] Existing technologies suffer from problems such as complex experimental platform structures, highly complex control methods, and the fact that they mainly only achieve partial weightlessness. Summary of the Invention

[0005] This application provides a method for controlling planetary gravitational acceleration, which can, to some extent, solve the problems of complex experimental platform structures, high control method complexity, and the fact that it mainly only achieves partial weightlessness.

[0006] In a first aspect, embodiments of this application provide a method for controlling planetary gravitational acceleration, applied to a gravity drop tower device. The gravity drop tower device includes a guide rail module, an experimental drop chamber module, a connecting module, a counterweight, and a gravity acceleration control module. The control module drives a motor in the experimental drop chamber module to control the acceleration of the experimental drop chamber along the direction of gravity in each guide rail to be a constant planetary gravitational acceleration. Control methods include: Based on the driving force of the motor, the tension of the rope, the friction, the air resistance, the acceleration of gravity of the earth, the mass of the experimental landing capsule and the acceleration of gravity of the planet, the dynamic equation of the experimental landing capsule is determined, and the acceleration of gravity of the planet is the second derivative of the displacement of the landing capsule. Based on the control variables, state variables, and experimental landing mass, the dynamic equations are transformed into first-order state variable equations and displacement equations. Based on the first-order state variable equation and displacement equation, determine the control variables and state variables at the current moment; Based on the control variables and state variables, state matrix, control matrix and output matrix at the current moment, determine the predicted state variables and predicted displacement at the next moment; Based on the initial altitude, initial velocity, planetary gravitational acceleration, and time step, determine the target trajectory after the current moment; Based on the prediction time step, control weight matrix, input control variables at the current time, prediction parameters after the current time, and target trajectory, the minimum value of the objective function is determined. The prediction parameters include prediction state variables and prediction control variables. Based on the predicted displacement at the current moment, the target trajectory at the next moment, the gain matrix, and the control variables at the current moment corresponding to the minimum value of the objective function, the control law equation is determined. Based on the control law equation, the first constraint condition of planetary gravitational acceleration, and the second constraint condition of the control variables, the experimental capsule is controlled to fall along the direction of gravity in each guide rail with planetary gravitational acceleration.

[0007] In one embodiment, the dynamic equation is calculated as follows:

[0008] in, m For the experimental landing mass; This is the second derivative of the experimental capsule displacement, and also the planetary gravitational acceleration; g This refers to the acceleration due to Earth's gravity. F m For motor driving force; F t The tension in the rope; F f Friction; F a This refers to air resistance.

[0009] In one embodiment, the formula for calculating the first-order state variable equation is:

[0010] The formula for calculating the displacement equation is:

[0011] in, z Let these be the state variables, where the landing displacement and the velocity of the landing displacement are the state variables, and their expressions are as follows: , For cabin displacement The first derivative; u The control variable is the motor driving force; The first derivative of the state variable; m For the experimental landing mass; hThis refers to the displacement of the landing cabin.

[0012] In one embodiment, the formula for calculating the predicted state variable at the next time step is:

[0013] The formula for calculating the predicted displacement at the next moment is:

[0014] in, u k|k For time step k Control variables at any given time; z k|k For time step k The state variable at any given time; For time step k Time to k Predicted state variables at time +1; A The state matrix, , I It is the identity matrix. (1,1,...,1,1) T B For the control matrix, ; C This is the output matrix; For time step k Time to k Predicted displacement at time +1; t For time.

[0015] In one embodiment, the formula for calculating the target trajectory is:

[0016] in, r k+i For time step k + i The target trajectory at any given moment i The number of time steps, i Integers greater than or equal to 0; h 0 represents the initial altitude of the experimental landing capsule; v 0 represents the initial velocity of the experimental landing capsule; a d For planetary gravitational acceleration, the first constraint is: amin ≦ a d ≦ a max .

[0017] In one embodiment, the objective function is calculated as follows:

[0018] in, J For time step k Time to k + i The minimum value of the objective function between the predicted state variables and the target trajectory at time t; U ( k (Time step) k Input control variables at any given time, ; z k+i|k For time step k Time to k + i Predicted state variables at time t; r k+i For time step k + i The target trajectory at any given moment; λ To control the weight matrix, ; u k+i|k for k Time to k + i Predictive control variables at any given time; p The predicted time step is the number of predicted time steps. , ... All are intermediate variables.

[0019] In one embodiment, the formula for calculating the control law equation is:

[0020] in, u k The time step corresponding to the minimum value of the objective function k The control variable at time t, the second constraint is u min ≦ u k ≦u max ; K mpc This is the gain matrix of the predictive control model; r k+1 For time step k The target trajectory at time +1; For time step k Predicted displacement at time.

[0021] In one embodiment, the guide rail module includes at least two guide rails arranged along the direction of gravity, one end of each guide rail is fixed to the ground, and the connecting module is located at the other end of the guide rail module away from the ground. The experimental landing module includes an experimental landing cabin and a motor, and the connecting module includes a rope. The connecting module connects the top of the experimental landing cabin to the counterweight through the rope. The experimental landing cabin is located between the guide rails.

[0022] In one embodiment, the mass of the counterweight is greater than the mass of the experimental landing chamber; the experimental landing chamber module also includes couplings on both sides of the experimental landing chamber, a moving shaft parallel to the guide rail, and pulleys provided on the couplings. The pulleys correspond to the guide rails. The motor drives the moving shafts, and the moving shafts drive the experimental landing chambers to move along the direction of gravity on the guide rails following the pulleys through the couplings. Planetary gravitational acceleration a d The range of values ​​for is: 0 ≦ a d ≤9.8m / s 2 .

[0023] In one embodiment, the mass of the counterweight is less than the mass of the experimental landing capsule; planetary gravitational acceleration. a d The range of values ​​for is: 0 < a d The experimental landing module also includes couplings on both sides of the experimental landing, a moving shaft parallel to the guide rail, and pulleys on the couplings. The guide rail is equipped with a braking mechanism. The motor drives the moving shaft. When the preset conditions are met, the braking mechanism applies a braking force to the pulley in the opposite direction of gravity. The moving shaft drives the experimental landing to follow the pulley and move along the direction of gravity on the guide rail through the coupling.

[0024] The beneficial effects of the embodiments in this application compared with the prior art are: The planetary gravitational acceleration control method of this application is applied to a gravity drop tower device. Since the gravity drop tower device includes a guide rail module, an experimental drop chamber module, a connecting module, a counterweight, and a gravity acceleration control module, the control module drives a motor in the experimental drop chamber module to control the acceleration of the experimental drop chamber along the gravitational direction in each guide rail to a constant planetary gravitational acceleration. This simplifies the structure of the planetary gravitational acceleration experimental platform and reduces its cost. By constructing the dynamic equations of the experimental drop chamber and transforming them into first-order state variable equations and displacement equations, a predicted trajectory is obtained based on the state variables and control variables. The minimum value of the objective function is determined by the error between the predicted trajectory and the target trajectory. Based on the control variables corresponding to the minimum value of the objective function, the control law equation for the planetary gravitational acceleration of the experimental drop chamber is determined. Finally, based on the constraints and the control law equation, the experimental drop chamber is controlled to fall along the gravitational direction in each guide rail with planetary gravitational acceleration. This simplifies the control method, reduces its complexity, improves the smoothness and accuracy of controlling planetary gravitational acceleration, and thus reduces the cost of planetary gravitational acceleration experiments. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the gravity-assisted tower-dropping device provided in one embodiment of this application; Figure 2 This is a flowchart illustrating a method for controlling planetary gravitational acceleration according to an embodiment of this application; Reference numerals for each figure: 1. Connecting module; 2. Counterweight; 3. Guide rail; 31. Moving shaft; 4. Experimental landing chamber; 41. Coupling; 5. Motor; 6. Rope. Detailed Implementation

[0027] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0028] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0029] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0030] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0032] The technical solution of this application will be described below through specific embodiments.

[0033] Currently, there are various experimental methods for simulating planetary gravity space environments, including ground-based micro / low gravity drop towers, weightless aircraft in parabolic flight, microgravity experimental rockets, microgravity experimental satellites, and space stations. These facilities can all put objects in a state of complete or partial weightlessness.

[0034] However, existing gravity experiment platforms have numerous components, complex structures, and very high equipment and maintenance costs. Correspondingly, the control methods are also highly complex. Furthermore, existing technologies mainly simulate partial weightlessness of objects in various planetary gravity environments.

[0035] To overcome the aforementioned technical problems to some extent, this application provides a method for controlling planetary gravitational acceleration, applied to a gravity-assisted drop tower device, such as... Figure 1As shown, the gravity drop tower device includes a guide rail module, an experimental drop chamber module, a connecting module 1, a counterweight 2, and a gravity acceleration control module. The guide rail module includes at least two guide rails 3 arranged along the direction of gravity, with one end of each guide rail 3 fixed to the ground. The connecting module 1 is located at the other end of the guide rail module away from the ground. The experimental drop chamber module includes an experimental drop chamber 4 and a motor 5. The connecting module includes a rope 6. The control module drives the motor 5 to control the acceleration of the experimental drop chamber 4 along the direction of gravity in each guide rail 3 to be a constant planetary gravitational acceleration. The connecting module connects the top of the experimental drop chamber 4 to the counterweight 2 through the rope 6. The experimental drop chamber 4 is located between each guide rail 3, which simplifies the structure of the planetary gravitational acceleration experimental platform and reduces the cost of the experimental platform.

[0036] like Figure 2 As shown, a method for controlling planetary gravitational acceleration includes: S10, based on the motor driving force of the motor, the rope tension, the friction between the experimental landing capsule and the guide rail, the air resistance of the experimental landing capsule, the Earth's gravitational acceleration, the mass of the experimental landing capsule and the planetary gravitational acceleration, determine the dynamic equation of the experimental landing capsule, where the planetary gravitational acceleration is the second derivative of the landing capsule displacement.

[0037] In one embodiment, the dynamic equation is calculated as follows:

[0038] in, m For the experimental landing mass; This is the second derivative of the experimental capsule displacement, and also the planetary gravitational acceleration; g This refers to the acceleration due to Earth's gravity. F m For motor driving force; F t The tension in the rope; F f Friction; F a This refers to air resistance.

[0039] In this embodiment, based on the force analysis of the experimental landing capsule, the direction of the motor's driving force is downward, the direction of the rope's tension is upward, the direction of the frictional force between the experimental landing capsule and the guide rail is upward, the direction of the air resistance of the experimental landing capsule is upward, the direction of the Earth's gravitational acceleration is downward, and the direction of the planetary gravitational acceleration is downward. The dynamic equations of the experimental landing capsule are determined according to Newton's laws. Because there are no additional complex structures, the complexity of the force analysis and the dynamic equations are reduced, thus improving the computational efficiency of the control method.

[0040] S20, based on control variables, state variables and experimental landing mass, transforms the dynamic equations into state-space equations. The state-space equations include first-order state variable equations and displacement equations. The control variable is the motor driving force, and the state variables are the landing displacement and the velocity of the landing displacement. The velocity of the landing displacement is the first derivative of the landing displacement.

[0041] In one embodiment, the formula for calculating the first-order state variable equation is:

[0042] The formula for calculating the displacement equation is:

[0043] in, z Let these be the state variables, where the landing displacement and the velocity of the landing displacement are the state variables, and their expressions are as follows: , For cabin displacement The first derivative; u The control variable is the motor driving force; The first derivative of the state variable; m For the experimental landing mass; h This refers to the displacement of the landing cabin.

[0044] In this embodiment, after introducing control variables and state variables, the dynamic equations are transformed into state-space equations, thereby associating the control variables with the state variables and associating the state variables with the landing displacement.

[0045] S30, based on the first-order state variable equation and displacement equation, determines the control variable and the state variable at the current moment.

[0046] S40, based on the control variables, state variables, state matrix, control matrix and output matrix at the current time, determine the predicted state variables and predicted displacement at the next time.

[0047] In one embodiment, S40 includes: determining the predicted state variable for the next moment based on the control variable, the state variable, the state matrix, and the control matrix at the current moment; determining the predicted displacement for the next moment based on the predicted state variable and the output matrix at the next moment, thereby establishing a prediction model, and determining the predicted state variable and the predicted displacement for the next moment through the control variable, the state variable, and the control variable at the current moment.

[0048] In one embodiment, the formula for calculating the predicted state variable at the next time step is:

[0049] The formula for calculating the predicted displacement at the next moment is:

[0050] in, u k|k For time step k Control variables at any given time; z k|k For time step k The state variable at any given time; For time step k Time to k Predicted state variables at time +1; A The state matrix, , I It is the identity matrix. (1,1,...,1,1) T B For the control matrix, ; C This is the output matrix; For time step k Time to k Predicted displacement at time +1; t For time.

[0051] S50 determines the target trajectory after the current moment based on the initial altitude of the experimental landing capsule, the initial velocity of the experimental landing capsule, the planetary gravitational acceleration, and the time step.

[0052] In one embodiment, the formula for calculating the target trajectory is:

[0053] in, r k+i For time stepk + i The target trajectory at any given moment i The number of time steps, i Integers greater than or equal to 0; h 0 represents the initial altitude of the experimental landing capsule; v 0 represents the initial velocity of the experimental landing capsule; a d For planetary gravitational acceleration, the first constraint is: a min ≦ a d ≦ a max .

[0054] In this embodiment, the target trajectory after the current moment is determined based on the initial altitude of the experimental landing capsule, the initial velocity of the experimental landing capsule, the planetary gravitational acceleration, and the time step. This determines the trajectory benchmark of the experimental landing capsule, which facilitates the comparison between the predicted trajectory and the target trajectory, thereby adjusting the control variables.

[0055] It should be noted that the time step k Moment, time step k+1 Moment, time step k+i The time interval is also the sampling time. The time interval between two samplings is set according to the needs of the scenario, such as 0.5 milliseconds, 1 millisecond, etc.

[0056] S60, based on the input control variables at the current time, the predicted state variables after the current time, the target trajectory after the current time, the predicted time step, the control weight matrix, and the predicted control variables after the current time, determine the minimum value of the objective function.

[0057] In one embodiment, the objective function is calculated as follows:

[0058] in, J For time step k Time to k + i The minimum value of the objective function between the predicted state variables and the target trajectory at time t; U ( k (Time step) k Input control variables at any given time, ; z k+i|k For time step k Time to k +i Predicted state variables at time t; r k+i For time step k+i The target trajectory at any given moment; λ To control the weight matrix, , , ... All are intermediate variables u k+i|k For time step k Time to k + i Predictive control variables at any given time; p The predicted time step is the number of predicted time steps.

[0059] In this embodiment, based on the structure of the gravity drop tower device, the current input control variables are used in the objective function to obtain the corresponding trajectory error and control error. When the trajectory error and control error of the experimental drop chamber are minimized, the control accuracy of the planetary gravitational acceleration of the gravity drop tower device can be improved.

[0060] S70, based on the predicted displacement at the current moment, the target trajectory at the next moment, the gain matrix, and the control variables at the current moment corresponding to the minimum value of the objective function, determine the control law equation for the planetary gravitational acceleration of the experimental landing capsule.

[0061] In one embodiment, the formula for calculating the control law equation is:

[0062] in, u k The time step corresponding to the minimum value of the objective function k The control variable at time t, the second constraint is u min ≦ u k ≦ u max ; K mpc This is the gain matrix of the predictive control model; r k+1 For time step k The target trajectory at time +1; For time step k Predicted displacement at time.

[0063] S80, based on the control law equation, the first constraint condition of planetary gravitational acceleration, and the second constraint condition of the control variables, controls the experimental landing capsule to fall along the direction of gravity in each guide rail with planetary gravitational acceleration.

[0064] In this embodiment, when the control variable is within the control range of the motor, the control variable is adjusted according to the requirements of planetary gravitational acceleration, and the planetary gravitational acceleration is selected according to the requirements of the experimental scenario; the experimental scenarios include microgravity acceleration, low gravity acceleration, Earth's gravitational acceleration, and hypergravity acceleration; thereby realizing multi-scenario operation of the experimental platform and further reducing the experimental cost.

[0065] In one embodiment, the guide rail of the gravity drop tower device is 2.5 m to 10 m high; a fastener is provided at the end of the guide rail near the ground, and part of the fastener is inserted into the ground to maintain the stability of the guide rail during the test.

[0066] In one embodiment, the mass of counterweight 2 is greater than the mass of experimental landing chamber 4; such as Figure 1 As shown, the experimental landing module also includes couplings 41 on both sides of the experimental landing capsule 4, a moving shaft 31 parallel to the guide rail 3, and pulleys provided on the couplings 41. Figure 1 (Not shown in the image), the pulley and guide rail 3 correspond to each other, the motor 5 drives the moving shaft 31, and the moving shaft 31 drives the experimental drop chamber 4 to move along the direction of gravity on the guide rail 3 following the pulley; planetary gravitational acceleration a d The range of values ​​for is: 0 ≦ a d ≤9.8m / s 2 In this embodiment, since the mass of the counterweight is greater than the mass of the experimental drop chamber, the counterweight increases the tension of the rope through the rope. When the planetary gravitational acceleration is less than or equal to the Earth's gravitational acceleration, the motor driving force output by the motor can be reduced, thereby reducing the energy consumption of the gravity drop tower device and increasing the lifespan of the gravity drop tower device.

[0067] In another embodiment, the mass of counterweight 2 is less than the mass of experimental landing capsule 4; planetary gravitational acceleration. a d The range of values ​​for is: 0 < a d The experimental landing module also includes couplings 41 on both sides of the experimental landing chamber 4, a moving shaft 31 parallel to the guide rail 3, and pulleys installed on the couplings 41. Figure 1 (Not shown in the image) The guide rail 3 is equipped with a braking mechanism ( Figure 1(Not shown in the image), motor 5 drives the moving shaft 31, and the braking mechanism applies a braking force to the pulley in the opposite direction of gravity when the preset conditions are met. The moving shaft 31 drives the experimental landing chamber 4 to move along the guide rail 3 in the direction of gravity, following the pulley, through the coupling 41. The preset condition is that the planetary gravitational acceleration is less than the Earth's gravitational acceleration. In this embodiment, since the mass of the counterweight is less than the mass of the experimental landing capsule, the counterweight reduces the tension of the rope via the rope. When the planetary gravitational acceleration is greater than or equal to the Earth's gravitational acceleration, there is no need for a braking mechanism to apply a braking force opposite to the direction of gravity to the pulley, further reducing the motor's output driving force, thereby reducing the energy consumption of the gravity landing tower device and increasing its lifespan. When the planetary gravitational acceleration is less than the Earth's gravitational acceleration, to avoid the counterweight significantly reducing the rope tension via the rope, a braking mechanism needs to apply a braking force opposite to the direction of gravity to the pulley, thereby reducing the planetary gravitational acceleration of the experimental landing capsule to meet the requirements of the scenario and avoid excessive motor output driving force, thus reducing the energy consumption of the gravity landing tower device and increasing its lifespan.

[0068] In one embodiment, the motor driving force output by the motor is controlled by controlling the current and / or voltage of the motor, and the motor driving force then drives the moving shaft. Through rolling optimization, the motor driving force output by the motor corresponds to the target trajectory of the experimental landing capsule, thereby controlling the experimental landing capsule to fall along the direction of gravity in each guide rail with planetary gravitational acceleration.

[0069] The beneficial effects of the embodiments in this application compared with the prior art are: The planetary gravitational acceleration control method of this application is applied to a gravity drop tower device. The gravity drop tower device includes a guide rail module, an experimental drop chamber module, a connecting module, a counterweight, and a gravity acceleration control module. The guide rail module includes at least two guide rails arranged along the direction of gravity, with one end of each guide rail fixed to the ground. The connecting module is located at the other end of the guide rail module away from the ground. The experimental drop chamber module includes an experimental drop chamber and a motor. The connecting module includes ropes. The control module drives the motor to control the acceleration of the experimental drop chamber along the direction of gravity in each guide rail to be a constant planetary gravitational acceleration. The connecting module connects the top of the experimental drop chamber to the counterweight via ropes. The experimental drop chamber is positioned between the guide rails. This method simplifies the control of planetary gravitational acceleration. The structure of the experimental platform reduces its cost. By constructing the dynamic equations of the experimental landing capsule and transforming them into first-order state variable equations and displacement equations, a predicted trajectory is obtained based on the state variables and control variables. The minimum value of the objective function is determined by the error between the predicted trajectory and the target trajectory. Based on the control variables corresponding to the minimum value of the objective function, the control law equation for the planetary gravitational acceleration of the experimental landing capsule is determined. Finally, based on the constraints and the control law equations, the experimental landing capsule is controlled to fall along the direction of gravity in each guide rail with planetary gravitational acceleration. This simplifies the control method, reduces its complexity, and improves the smoothness and accuracy of controlling planetary gravitational acceleration, thereby reducing the cost of planetary gravitational acceleration experiments.

[0070] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0071] The method for controlling planetary gravitational acceleration provided in this application can be applied to terminal devices such as mobile phones, tablets, wearable devices, in-vehicle devices, augmented reality (AR) / virtual reality (VR) devices, laptops, ultra-mobile personal computers (UMPCs), netbooks, and personal digital assistants (PDAs). This application does not impose any restrictions on the specific type of terminal device.

[0072] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of this application can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms.

[0073] The computer-readable medium may include at least: any entity or device capable of carrying computer program code to a photographic device / terminal device, recording media, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media. Examples include USB flash drives, portable hard drives, magnetic disks, or optical discs. In some jurisdictions, according to legislation and patent practice, computer-readable media may not be electrical carrier signals or telecommunication signals.

[0074] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0075] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0076] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus / network device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0077] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0078] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for controlling planetary gravitational acceleration, characterized in that, It is applied to a gravity drop tower device, which includes a guide rail module, an experimental drop chamber module, a connecting module, a counterweight, and a gravity acceleration control module. The control module drives the motor in the experimental drop chamber module to control the acceleration of the experimental drop chamber along the direction of gravity in each guide rail to be a constant planetary gravity acceleration. Control methods include: Based on the driving force of the motor, the tension of the rope, the friction, the air resistance, the acceleration due to gravity of the Earth, the mass of the experimental landing capsule and the acceleration due to gravity of the planet, the dynamic equation of the experimental landing capsule is determined, and the acceleration due to gravity of the planet is the second derivative of the displacement of the landing capsule. Based on the control variables, state variables, and experimental landing mass, the dynamic equations are transformed into first-order state variable equations and displacement equations. Based on the first-order state variable equation and displacement equation, determine the control variables and state variables at the current moment; Based on the control variables and state variables, state matrix, control matrix and output matrix at the current moment, determine the predicted state variables and predicted displacement at the next moment; Based on the initial altitude, initial velocity, planetary gravitational acceleration, and time step, determine the target trajectory after the current moment; Based on the prediction time step, control weight matrix, input control variables at the current time, prediction parameters after the current time, and target trajectory, the minimum value of the objective function is determined. The prediction parameters include prediction state variables and prediction control variables. Based on the predicted displacement at the current moment, the target trajectory at the next moment, the gain matrix, and the control variables at the current moment corresponding to the minimum value of the objective function, the control law equation is determined. Based on the control law equation, the first constraint condition of planetary gravitational acceleration, and the second constraint condition of the control variables, the experimental capsule is controlled to fall along the direction of gravity in each guide rail with planetary gravitational acceleration.

2. The method for controlling planetary gravitational acceleration as described in claim 1, characterized in that, The formula for calculating the dynamic equation is: in, m For the experimental landing mass; This is the second derivative of the experimental capsule displacement, and also the planetary gravitational acceleration; g This refers to the acceleration due to Earth's gravity. F m For motor driving force; F t The tension in the rope; F f Friction; F a This refers to air resistance.

3. The method for controlling planetary gravitational acceleration as described in claim 1, characterized in that, The formula for calculating the first-order state variable equation is: The formula for calculating the displacement equation is: in, z Let these be the state variables, where the landing displacement and the velocity of the landing displacement are the state variables, and their expressions are as follows: , For cabin displacement The first derivative; u The control variable is the motor driving force; The first derivative of the state variable; m For the experimental landing mass; h This refers to the displacement of the landing cabin.

4. The method for controlling planetary gravitational acceleration as described in claim 1, characterized in that, The formula for calculating the predicted state variable at the next moment is: The formula for calculating the predicted displacement at the next moment is: in, u k|k For time step k Control variables at any given time; z k|k For time step k The state variable at any given time; For time step k Time to k + 1 Predicted state variables at time t; A The state matrix, , I It is the identity matrix. (1,1,...,1,1) T B For the control matrix, ; C This is the output matrix; For time step k Time to k + 1 Predicted displacement at time; t For time.

5. The method for controlling planetary gravitational acceleration as described in claim 1, characterized in that, The formula for calculating the target trajectory is: in, r k+i For time step k + i The target trajectory at any given moment i The number of time steps, i Integers greater than or equal to 0; h 0 represents the initial altitude of the experimental landing capsule; v 0 represents the initial velocity of the experimental landing capsule; a d For planetary gravitational acceleration, the first constraint is: a min ≦ a d ≦ a max .

6. The method for controlling planetary gravitational acceleration as described in claim 1, characterized in that, The objective function is calculated as follows: in, J For time step k Time to k + i The minimum value of the objective function between the predicted state variables and the target trajectory at time t; U ( k (Time step) k Input control variables at any given time, ; z k+i|k For time step k Time to k + i Predicted state variables at time t; r k+i For time step k + i The target trajectory at any given moment; λ To control the weight matrix, ; u k+i|k For time step k Time to k + i Predictive control variables at any given time; p The predicted time step is the number of predicted time steps. , ... All are intermediate variables.

7. The method for controlling planetary gravitational acceleration as described in claim 1, characterized in that, The formula for calculating the control law equation is: in, u k The time step corresponding to the minimum value of the objective function k The control variable at time t, the second constraint is u min ≦ u k ≦ u max ; K mpc This is the gain matrix of the predictive control model; r k+1 For time step k The target trajectory at time +1; For time step k Predicted displacement at time.

8. The method for controlling planetary gravitational acceleration as described in claim 1, characterized in that, The mass of the counterweight is greater than the mass of the experimental landing chamber; The experimental landing module also includes couplings on both sides of the experimental landing, a moving shaft parallel to the guide rail, and pulleys on the couplings. The pulleys correspond to the guide rails. The motor drives the moving shafts, and the moving shafts drive the experimental landing to move along the direction of gravity on the guide rails following the pulleys through the couplings. Planetary gravitational acceleration a d The range of values ​​for is: 0 ≦ a d ≤9.8m / s 2 .

9. The method for controlling planetary gravitational acceleration as described in claim 1, characterized in that, The mass of the counterweight is less than the mass of the experimental landing chamber.

10. The method for controlling planetary gravitational acceleration as described in claim 9, characterized in that, Planetary gravitational acceleration a d The range of values ​​for is: 0 < a d ; The experimental landing module also includes couplings on both sides of the experimental landing, a moving shaft parallel to the guide rail, and pulleys on the couplings. The guide rail is equipped with a braking mechanism. The motor drives the moving shaft. When the preset conditions are met, the braking mechanism applies a braking force to the pulley in the opposite direction of gravity. The moving shaft drives the experimental landing to move along the guide rail in the direction of gravity, following the pulley, through the coupling.

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