Water-air amphibious vehicle obstacle avoidance method and water-air amphibious vehicle

Abstract

The invention discloses a water-air amphibious vehicle obstacle avoidance method and a water-air amphibious vehicle. The obstacle avoidance method for the water-air amphibious vehicle comprises the following steps: acquiring a total impulse which can be provided by a propeller of the water-air amphibious vehicle; acquiring basic information of obstacles, basic information of the water-air amphibious vehicle at the current time point and time information of filling butane and oxygen into a mixing cavity; obtaining an optimal water outlet angle and an optimal water outlet distance; acquiring a ventilation time point and an ignition time point according to the barrier basic information and the time information of filling the butane and the oxygen into the mixing cavity; controlling a butane gas supply system and an oxygen supply system to inflate the reaction cavity according to the ventilation time point; and ignition is conducted in the reaction cavity according to the ignition time point, so that the water-air amphibious aircraft obtains the total impulse. The invention designs an obstacle avoidance method for a water-air amphibious vehicle. The blank that obstacle avoidance cannot be performed in a water-air medium conversion mode in the prior art is filled.

Description

Technical Field

[0001] The present application relates to the technical field of aircraft, and in particular to an obstacle avoidance method for an amphibious water-air aircraft and an amphibious water-air aircraft. Background Art

[0002] With the continuous development of multi-modal aircraft research, water-air cross-medium amphibious aircraft are gradually becoming an emerging direction for human research and development of marine equipment. Figure 1 As shown in the figure, the water-air amphibious cross-medium vehicle has the ability to move in the air and in the ocean, and can flexibly switch between air and underwater working scenes to avoid underwater and air obstacles. When it is necessary to travel at high speed to reach the destination, the vehicle can enter the air for low-power long-term navigation; when underwater operations are required, it can dive underwater. These movement characteristics enable the water-air amphibious cross-medium vehicle to have the ability to completely independently perform complex tasks such as shipwreck rescue, marine sample collection, and marine archaeology without the need for large ships or drones. This has broad application prospects in future ocean exploration.

[0003] The density of water is 700 times higher than that of air, so the design of the power system is crucial for the vehicle to cross the water and enter the air. One type of vehicle uses a brushless motor to drive a propeller to achieve medium crossing, but the propeller needs to be continuously accelerated to generate enough propulsion to pull the vehicle out of the water, and the two-phase crossing time is long.

[0004] The propeller form inherits the design concept of aerial vehicles, which reduces the difficulty of research and development in terms of control method and structural design, but it also faces the inherent problems of cavitation and erosion of propellers underwater. Inspired by the flying squid in nature, which can quickly escape from the ocean into the air by compressing the jet through muscles, some studies have begun to propose the use of jet propulsion to achieve water-to-air crossing.

[0005] Jet propulsion is a form of propulsion that generates high momentum in a short period of time and releases high energy density. Prototypes using this type of propulsion can leave the water at a faster speed.

[0006] However, the prior art amphibious vehicles only achieve simple driving in water and simple flying in the air, and how to perform obstacle avoidance operations in water by utilizing the advantages of amphibious vehicles is not considered in the prior art. Summary of the invention

[0007] The object of the present invention is to provide an obstacle avoidance method for an amphibious vehicle to solve at least one of the above-mentioned technical problems.

[0008] One aspect of the present invention provides an obstacle avoidance method for an amphibious vehicle, the obstacle avoidance method for an amphibious vehicle comprising:

[0009] Obtain the total impulse that can be provided by the propeller of the water-air amphibious vehicle;

[0010] Obtain basic information about obstacles, basic information about the current time point of the water-air amphibious vehicle, and information about the time when butane and oxygen are filled into the mixing chamber;

[0011] Obtaining the optimal water exit angle and the optimal water exit distance according to the basic information of the obstacle, the time information of butane and oxygen filling into the mixing chamber, and the basic information of the water-air amphibious vehicle at the current time point;

[0012] The ventilation time point and the ignition time point are obtained according to the basic information of the obstacle and the time information of butane and oxygen filling into the mixing chamber;

[0013] Controlling the butane gas supply system and the oxygen supply system to inflate the reaction chamber according to the ventilation time point;

[0014] Ignition is performed in the reaction chamber according to the ignition timing, so that the water-air amphibious vehicle obtains the total impulse.

[0015] Optionally, the water-air amphibious vehicle obstacle avoidance method further comprises:

[0016] The propeller is started when the water-air amphibious vehicle flies out of the water at the preset position.

[0017] Optionally, the basic obstacle information includes distance information between the obstacle and the amphibious water and air vehicle, position information of the obstacle relative to the amphibious water and air vehicle, and obstacle height information;

[0018] The basic information of the amphibious water-air vehicle at the current time point includes the pitch attitude angle at the current time point, the current position coordinates of the amphibious water-air vehicle, the vehicle mass information, and the moment of inertia of the vehicle around the z-axis.

[0019] Optionally, the total impulse that can be provided by the propeller of the water-air amphibious vehicle is obtained by the following formula:

[0020] in,

[0021] J(C) is the total impulse that the propeller of the amphibious vehicle can provide, C is the fuel concentration, when C=1, the system undergoes a stoichiometric reaction, when C<1, it is in an oxygen-rich state, at the end of the reaction, there is excess oxygen, which inhibits the production of by-products and reduces the risk of flashback. The value of C determines the degree of reaction activity, thereby affecting the generation of explosive reaction propulsion, t is the duration of propulsion, T jet The jet propulsion force.

[0022] Optionally, the obtaining of the optimal water exit angle and the optimal water exit distance according to the basic information of the obstacle, the time information of butane and oxygen being filled into the mixing chamber, and the basic information of the water-air amphibious vehicle at the current time point includes:

[0023] Acquire a water outlet angle and navigation track database, wherein the water outlet angle and navigation track database includes at least one preset water outlet angle and navigation track information corresponding to each preset water outlet angle;

[0024] According to the distance information between the obstacle and the amphibious vehicle and the time information of butane and oxygen being filled into the mixing chamber in the basic information of the obstacle, the distance information between the obstacle and the amphibious vehicle after butane and oxygen are filled into the mixing chamber is obtained, and the distance information between the obstacle and the amphibious vehicle after butane and oxygen are filled into the mixing chamber is called the first distance information;

[0025] The optimal water-outlet angle and the optimal water-outlet distance are obtained according to the first distance information, the height information of the obstacle and each navigation trajectory information.

[0026] Optionally, acquiring the optimal water-outlet angle and the optimal water-outlet distance according to the first distance information, the height information of the obstacle and each navigation track information includes:

[0027] Obtain time constraints, highest point trajectory height constraints, power transition smoothness constraints, and water surface separation angle constraints;

[0028] Acquire navigation trajectory information that simultaneously satisfies the time constraint condition, the highest point trajectory height constraint condition, the power transition smoothness constraint condition, and the water surface separation angle constraint condition;

[0029] When there is only one navigation track information that satisfies the time constraint, the highest point trajectory height constraint, the power transition smoothness constraint, and the water surface separation angle constraint, obtaining the water exit angle corresponding to the navigation track information as the optimal water exit angle;

[0030] The walking distance between the initial point of the navigation track information and the highest point of the navigation track information is obtained as the optimal water outlet distance.

[0031] Optionally, the time constraint condition includes:

[0032] t peak ≥t prop

[0033] in,

[0034] t prop is the acceleration time, t peakis the time required for the vehicle to reach the highest point of the obstacle from the water surface, and the linear growth rate of the propeller thrust is k p .

[0035] Optionally, the highest point trajectory height constraint condition includes:

[0036] in,

[0037] The power transition smoothness constraint conditions include:

[0038] in,

[0039] α max is the maximum allowed rate of pitch angle change, which is used to avoid instability caused by drastic attitude adjustments;

[0040] The water surface departure angle constraint conditions include:

[0041] φ min ≤φ0≥φ max ;in,

[0042] φ min and φ max Determined based on specific mission requirements and thruster limitation angles.

[0043] The present application also provides a water-air amphibious aircraft, the water-air amphibious aircraft comprising:

[0044] Aircraft hull;

[0045] A propeller, one end of which extends into the shell of the aircraft, a mixing chamber is provided in the propeller, the mixing chamber comprises a butane air inlet, an oxygen air inlet, a pressure liquid injection port, and a liquid injection port, the mixing chamber contains liquid, the pressure liquid injection port is located at the end of the propeller away from the shell of the aircraft, and an ignition device is provided in the mixing chamber;

[0046] a butane gas supply system, the butane gas supply system being disposed in the aircraft shell and being in communication with the butane gas inlet for providing pressurized butane gas into the mixing chamber;

[0047] An oxygen supply system, the oxygen supply system is arranged in the aircraft shell, the oxygen supply system is connected to the oxygen inlet, and is used to provide pressurized oxygen to the mixing chamber; wherein,

[0048] When the pressurized butane gas and pressurized oxygen enter the mixing chamber and the pressure in the mixing chamber reaches a preset threshold, ignition is performed through an ignition device, so that the pressurized butane gas and pressurized oxygen in the mixing chamber explode to generate thrust for expelling liquid from the pressurized liquid injection port.

[0049] Optionally, the water-air amphibious vehicle further comprises:

[0050] a propeller, the propeller being arranged on the aircraft hull;

[0051] A propeller driving system is disposed in the aircraft shell and connected to the propeller to drive the propeller to rotate.

[0052] Beneficial Effects

[0053] The obstacle avoidance method for water-air amphibious aircraft designed in this application proposes a joint control strategy for the fuel explosion jet propulsion system and the propeller propulsion system, breaking through the bottleneck of the existing single propulsion technology in the process of water-air medium conversion, which is poor in speed and sustainability and cannot effectively achieve obstacle avoidance. Traditional amphibious aircraft often face different control challenges in underwater and air environments. The present invention constructs a system with air movement capabilities and water-air shuttle capabilities. Through a unique control strategy, a method for obstacle avoidance that can simultaneously deal with underwater and air obstacles is proposed. In the underwater stage, the aircraft only needs to pay attention to the height of the obstacle. After spraying the water surface, the fuel explosion jet propulsion can quickly generate a strong propulsion force to push the aircraft to break through the water surface, and drive the propeller system within the time interval calculated by the algorithm to ensure that the aircraft can obtain continuous and sufficient propulsion force and stably enter the level flight posture. In the air stage, the propeller propulsion continues to maintain the stability of the aircraft and provide it with continuous power. The innovation of this method lies in that, by jointly controlling jet propulsion and propeller propulsion, it not only solves the problem that a single propulsion system in traditional technology cannot take into account the propulsion needs both underwater and in the air, but also realizes efficient obstacle avoidance during the water-to-air conversion process. After the jet is ejected on the water surface, the aircraft can quickly respond to environmental changes and connect the propeller system to propel it away from obstacles to ensure navigation safety. This solution can break through the water surface at high speed when shuttling between water and air, and can give full play to the advantages of propellers in the air, thereby effectively improving the maneuverability, stability and ability of the aircraft to adapt to complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a flow chart of an obstacle avoidance method for an amphibious air vehicle according to an embodiment of the present application.

[0055] Figure 2 It is a schematic diagram of the structure of an amphibious water-air vehicle in one embodiment of the present application.

[0056] Figure 3 It is a schematic diagram of the conversion from water medium to air medium of a water-air amphibious vehicle in one embodiment of the present application.

[0057] Figure 4 It is a schematic diagram of the electronic system and gas control circuit of an amphibious air vehicle in one embodiment of the present application.

[0058] Figure 5 It is a schematic diagram of an obstacle leaping by an amphibious air vehicle in one embodiment of the present application.

[0059] Figure 6 It is a structural schematic diagram of a six-dimensional force measuring platform in one embodiment of the present application.

[0060] Figure 7 It is a schematic diagram of the fuel mixing ratio experimental results of the tethered prototype in one embodiment of the present application.

[0061] Figure 8 It is a schematic diagram of the transition from surface launch to air posture change in one embodiment of the present application.

[0062] Reference numerals:

[0063] 1. Propeller; 2. Aircraft hull. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0065] like Figure 1 The obstacle avoidance method for the water-air amphibious vehicle shown includes:

[0066] Step 1: Obtain the total impulse that can be provided by the propeller of the water-air amphibious vehicle;

[0067] Step 2: Obtain basic information about obstacles, basic information about the current time point of the water-air amphibious vehicle, and information about the time when butane and oxygen are filled into the mixing chamber;

[0068] Step 3: Obtain the optimal water exit angle and optimal water exit distance according to the basic information of the obstacle, the time information of butane and oxygen filling into the mixing chamber, and the basic information of the water-air amphibious vehicle at the current time point;

[0069] Step 4: Obtain the ventilation time point and the ignition time point according to the basic information of the obstacle and the time information of butane and oxygen filling into the mixing chamber;

[0070] Step 5: Control the butane gas supply system and the oxygen supply system to inflate the reaction chamber according to the ventilation time point;

[0071] Step 6: Ignite the reaction chamber according to the ignition time point, so that the water-air amphibious vehicle obtains the total impulse.

[0072] The present application designs an obstacle avoidance method for a water-to-air amphibious vehicle, which fills the gap in the prior art that is unable to avoid obstacles through water-to-air medium conversion. When underwater, the present application only needs to consider the height of the obstacle to determine the control scheme for the underwater and air parts, and directly drives the propeller to rotate after being ejected out of the water surface.

[0073] In this embodiment, the obstacle avoidance method for the water-air amphibious vehicle further includes:

[0074] The propeller is started when the preset position of the water-air amphibious aircraft flies out of the water. It is understandable that the position information can be obtained by attaching a depth sensor to the preset position on the surface of the aircraft.

[0075] In this embodiment, the basic obstacle information includes distance information between the obstacle and the amphibious vehicle, position information of the obstacle relative to the amphibious vehicle, and obstacle height information;

[0076] The basic information of the amphibious water-air vehicle at the current time point includes the pitch attitude angle at the current time point, the current position coordinates of the amphibious water-air vehicle, the vehicle mass information, and the moment of inertia of the vehicle around the z-axis.

[0077] In this embodiment, the total impulse that can be provided by the propeller of the water-air amphibious vehicle is obtained by the following formula:

[0078] in,

[0079] J(C) is the total impulse that the propeller of the amphibious vehicle can provide, C is the fuel concentration, when C=1, the system undergoes a stoichiometric reaction, when C<1, it is in an oxygen-rich state, at the end of the reaction, there is excess oxygen, which inhibits the production of by-products and reduces the risk of flashback. The value of C determines the degree of reaction activity, thereby affecting the generation of explosive reaction propulsion, t is the duration of propulsion, T jet(t, C) is the relationship function between propulsion force, time and fuel concentration.

[0080] In this embodiment, T jet (t, C) is obtained by the following formula:

[0081] in,

[0082] f(C) is the function of the relationship between the peak thrust and the fuel concentration, which can be fitted through experiments to determine the peak thrust pulse. The fuel concentration C and the chemical reaction rate k jointly determine the duration of the thrust pulse, b is the time offset, ρ w is the density of water, which is equal to 998 kg / m 3 , D is the diameter of the tail nozzle, and π is the pi.

[0083] In this embodiment, the obtaining of the optimal water exit angle and the optimal water exit distance according to the basic information of the obstacle, the time information of butane and oxygen filling into the mixing chamber, and the basic information of the water-air amphibious vehicle at the current time point includes:

[0084] A water outlet angle and navigation trajectory database is obtained, wherein the water outlet angle and navigation trajectory database includes at least one preset water outlet angle and navigation trajectory information corresponding to each preset water outlet angle; in the present embodiment, the navigation trajectory information includes the movement change trajectory of the water-air amphibious vehicle of the present application according to different angles after the mixing chamber is ignited. Specifically, the navigation trajectory information includes the position relationship of the water-air amphibious vehicle at each time point. For example, at the time point of 0 seconds, that is, when the gas in the mixing chamber has not yet been ignited, the initial position of the water-air amphibious vehicle is assumed to be (x1, y1). Then, after the mixing chamber is ignited, the positions at different time points are different. For example, at the time point of 1 second, its position may be (x2, y2).

[0085] According to the distance information between the obstacle and the amphibious vehicle and the time information of butane and oxygen being filled into the mixing chamber in the basic information of the obstacle, the distance information between the obstacle and the amphibious vehicle after butane and oxygen are filled into the mixing chamber is obtained, and the distance information between the obstacle and the amphibious vehicle after butane and oxygen are filled into the mixing chamber is called the first distance information;

[0086] The optimal water-outlet angle and the optimal water-outlet distance are obtained according to the first distance information, the height information of the obstacle and each navigation trajectory information.

[0087] In this embodiment, obtaining the optimal water-outlet angle and the optimal water-outlet distance according to the first distance information, the height information of the obstacle, and each navigation track information includes:

[0088] Obtain time constraints, highest point trajectory height constraints, power transition smoothness constraints, and water surface separation angle constraints;

[0089] Acquire navigation trajectory information that simultaneously satisfies the time constraint condition, the highest point trajectory height constraint condition, the power transition smoothness constraint condition, and the water surface separation angle constraint condition;

[0090] When there is only one navigation trajectory information that satisfies the time constraint, the highest point trajectory height constraint, the power transition smoothness constraint, and the water surface separation angle constraint at the same time, the water exit angle corresponding to the navigation trajectory information is obtained as the optimal water exit angle; it can be understood that if there are multiple ones, you can select any one, or make a selection by setting further conditions, for example, select the one with the highest height among all the navigation trajectory information that meets the conditions, or you can set other conditions yourself.

[0091] The walking distance between the initial point of the navigation track information and the highest point of the navigation track information is obtained as the optimal water outlet distance.

[0092] In this embodiment, the navigation track information can be obtained by the following formula:

[0093] The propulsion force T provided by the gas explosion in the mixing chamber of the present application is jet (t) from time t0 to time t jet Acting on the amphibious vehicle, the force arm is d1, and the speed of the amphibious vehicle increases from the initial speed v0 to v1.

[0094] According to the moment balance, the angular acceleration of the pitch angle change can be expressed as:

[0095]

[0096] Among them, L1 and L2 are the distances from the center of gravity to the top and bottom of the amphibious vehicle, respectively. This equation can be solved by numerical simulation.

[0097] The amphibious vehicle is under force balance, subject to gravity G and buoyancy F B , Water resistance F D and propulsion force T jet (t), the acceleration changes in the x and z directions of the spacecraft can be obtained:

[0098]

[0099] The equation of motion is:

[0100]

[0101]

[0102]

[0103]

[0104] Through the above formula, the theoretical position information of the amphibious vehicle per second when underwater can be obtained, thereby obtaining the navigation track information of the underwater section of the present application.

[0105] When the water-air amphibious vehicle of the present application is out of water but the propeller has not yet started, the navigation track information of the present application can be obtained by the following formula:

[0106] During this stage, the propeller does not provide thrust, and the vehicle is subject to gradually decreasing buoyancy, gravity and air resistance. The initial velocity is the speed at the end of the underwater acceleration stage, and the position is the water exit point.

[0107] The acceleration changes of the vehicle in the x and z directions are:

[0108]

[0109] Among them, v2(t) is the instantaneous velocity of the spacecraft, A proj (t) is the projected area of ​​the aircraft, S(t) is the wetted surface area of ​​the aircraft, which is related to the size of the aircraft; C p is the pressure drag coefficient, which depends on the shape of the vehicle and the fluid separation; C f is the friction coefficient, which is determined by the Reynolds number (can be calculated based on empirical formulas or approximate calculations for flat plate flow); V B (t) is the volume of the vehicle submerged in water that generates buoyancy. Similarly, the motion trajectories x2(t) and z2(t) can be obtained by numerical solution and integration.

[0110] The pitch angle is defined by a nonlinear second order differential equation.

[0111]

[0112] By solving the numerical method, the equation can be simplified under the condition of inertia dominance to obtain:

[0113]

[0114] in, d is the gravity and aerodynamic center moment. is the time factor of the pitch angle change.

[0115] Through the above formula, the theoretical position information of the amphibious air vehicle per second when the amphibious air vehicle is out of water but the propeller has not yet started can be obtained, thereby obtaining the navigation trajectory information of the amphibious air vehicle of the present application when it is out of water but the propeller has not yet started.

[0116] When the propeller of the water-air amphibious vehicle of the present application can provide lift, the navigation trajectory information of the present application can be obtained by the following formula:

[0117] Propeller start to transition to level flight attitude

[0118] 1. Propeller propulsion

[0119]

[0120] 2. Pitch changes

[0121] The pitch angle change is derived from the total moment,

[0122]

[0123] Among them, Mp, Mg and Ma are the dynamic moments of propeller thrust, gravity and air resistance respectively.

[0124] 3. Horizontal component

[0125]

[0126] Vertical Component

[0127]

[0128] Similarly, the integration gives the motion trajectory equations x3(t), z3(t) and the pitch angle change φ3(t).

[0129] In this embodiment, the time constraint conditions include:

[0130] t peak ≥t prop

[0131] in,

[0132] t prop is the propeller acceleration time, t peak is the time required for the vehicle to reach the highest point of the obstacle from the water surface, and the linear growth rate of the propeller thrust is k p .

[0133] In this embodiment, the highest point trajectory height constraint condition includes:

[0134] in,

[0135] The power transition smoothness constraint conditions include:

[0136] in,

[0137] α max is the maximum allowed rate of change of pitch angle. This constraint avoids instability caused by drastic attitude adjustment. The value can be adjusted according to the dynamic characteristics of the spacecraft (mass, pitch moment, fluid resistance, etc.) and is a fixed value.

[0138] The water surface departure angle constraint conditions include:

[0139] φ min ≤φ0≥φ max ;in,

[0140] φ min and φ max Determined based on specific mission requirements and thruster limitation angles.

[0141] The present application also provides an amphibious water-air craft, characterized in that the amphibious water-air craft comprises a craft hull 2, a propeller 1, a butane gas supply system and an oxygen supply system, wherein:

[0142] One end of the propeller 2 extends into the aircraft shell 1, and a mixing chamber is provided in the propeller 2. The mixing chamber includes a butane air inlet, an oxygen air inlet, a pressure liquid injection port, and a liquid injection port. The mixing chamber contains liquid. The pressure liquid injection port is located at the end of the propeller away from the aircraft shell, and an ignition device is provided in the mixing chamber.

[0143] A butane gas supply system is disposed in the aircraft shell, the butane gas supply system is in communication with the butane gas inlet, and is used to provide pressurized butane gas to the mixing chamber;

[0144] An oxygen supply system is disposed in the aircraft shell, and the oxygen supply system is connected to the oxygen inlet for providing pressurized oxygen to the mixing chamber; wherein,

[0145] When pressurized butane gas and pressurized oxygen enter the mixing chamber and the pressure in the mixing chamber reaches a preset threshold, the ignition device is used to ignite the pressurized butane gas and pressurized oxygen in the mixing chamber, thereby causing the pressurized butane gas and pressurized oxygen in the mixing chamber to explode and generate thrust for discharging the liquid from the pressurized liquid injection port.

[0146] The water-air amphibious vehicle of the present application further includes a propeller and a propeller drive system, wherein:

[0147] The propeller is arranged on the aircraft shell;

[0148] The propeller driving system is arranged in the aircraft shell, and the propeller driving system is connected to the propeller and is used to drive the propeller to rotate.

[0149] In one embodiment, the thruster prototype of the present application includes a gas supply system (butane gas supply system, oxygen supply system), a thruster and an electronic control system. The main body of the thruster is an aluminum alloy tube with an inner diameter of 40 mm, a length of 450 mm, and a wall thickness of 1 mm, which serves as a mixing chamber and a jet section for the explosion reaction. The aluminum alloy tube is made by metal 3D printing.

[0150] In order to reduce water resistance and prevent water from entering the components, the aircraft shell adopts the von Karman cone shape on the head while maintaining the fixed-wing shape of the prototype. The aircraft shell is a rotating body coaxial with the water tank, which is fastened to the water pipe through a sealing ring and isolates the electronic control system from water. The wing is made of polystyrene foam and is formed by cutting.

[0151] The gas supply system and the electronic control system are distributed around the water tank, and the overall center of gravity is located in the middle and upper part of the prototype. Due to the coaxial design, the distribution of components can be easily adjusted by forward and backward and rotational movement to change the center of gravity. The center of gravity is located behind the center of buoyancy, so it can have a positive pitch angle underwater. The components are concentrated on the top of the prototype, and the space reserved at the bottom can bear other loads, such as sensors, cameras, etc.

[0152] In order to perfectly complete the water-to-air crossing, the thruster needs to generate a large thrust in a short time. We chose a combination of butane and oxygen as the source of the reaction. The huge energy generated by their explosive reaction can generate enough reaction force to propel the prototype to take off from the water.

[0153] The explosion limit of butane in air is 1.5%-8.5%, so a precise gas dosing system needs to be given priority. The oxygen supply system (total weight 86g) includes a servo, a connecting steering plate (PLA material), a pressure reducing valve and an oxygen tank. The gas supply can be precisely controlled by controlling the angle and duration of the pressure reducing valve by a motor. We chose a butane gas cylinder for the butane gas supply system (total weight 51g), the top of which can be pressed to release butane gas through a connecting button (PLA material), which is also controlled by the servo. We chose a high-voltage generator (5V to 20KV) as the ignition device, and connected an iridium ignition needle at the high-voltage end, which can withstand high temperature and explosion shock, and provide support for continuous and stable multiple explosion jets.

[0154] The electronic system and gas control circuit of the water-air amphibious vehicle Figure 4As shown. We choose ATmega 328P chip as the microcontroller, which can meet the control requirements of the servo and relay. 2SLi-Po battery provides 7.4V power for the servo, and then reduces it to 5V through the step-down chip to power the microcontroller and micro relay. The prototype receives commands through the 433Mhz wireless transparent transmission module. 433Mhz is a low-frequency signal that can be effectively transmitted within a distance of less than 2m underwater, so it can support our remote control of the prototype's underwater actions.

[0155] The fuel gas supply process is as follows: Figure 4 As shown in the lower part. First, butane is introduced, and the servo rotates from the initial angle to the end position. Our test results show that within the pressing time range of 5-80ms, the volume of butane gas increases linearly and can be accurately controlled within the range of 20-80mL. Liquid butane is converted into gas under normal pressure, passes through the gas path in the button, and enters the water pipe through the one-way valve. This process takes an average of 5-10ms. The oxygen gas path can stably provide more than 6 times of 130mL of oxygen (depending on the oxygen content in the bottle) within 75ms-100ms by controlling the valve opening angle and opening time. After all the gases are introduced, the water level drops from 450mL to 300mL. Finally, a 5V voltage is input into the high-voltage generator through a relay, forming a high-temperature arc at the metal tip, igniting the mixed combustible gas in the tube and generating a jet.

[0156] The present application also provides a propulsion force testing method, and the propulsion force testing method of the present application includes:

[0157] A six-dimensional force measuring platform was built to test the propulsion and momentum generated by butane and oxygen at different mixing ratios to explore the amount of gas fuel corresponding to the maximum propulsion. The force measuring platform includes a water cylinder (2m×1m×1m), an aluminum profile fixing frame, a force sensor (1000Hz), a connecting fixture, and a test prototype (stainless steel, water content 600mL). The test prototype is fixed under the frame and connected to the slider. The slider can translate and convert the propulsion into pressure and transmit it to the force sensor. The displacement is controlled to be the same (400mL), the butane content is the same, and the oxygen content is changed to produce different fuel mixing ratios. The specific experimental parameters are shown in Table 1.

[0158] Table 1 Physical parameter settings for mixing ratio experiment

[0159]

[0160] In order to explore the different posture changes caused by launching the prototype from the water surface at different angles, we arranged the following Figure 6The scene shown in (b) includes a water tank (0.6m×0.3m×0.3m), an angle adjustment frame, a protective net, and a motion capture system (16 cameras). The prototype is fixed at different initial angles by a fixed frame. The pose information of the prototype is obtained by capturing the four markers attached to the surface of the prototype by the motion capture system. The specific experimental settings are shown in Table 2.

[0161] Table 2 Physical parameter settings for each experiment below

[0162]

[0163]

[0164] Figure 7 It is the result of the fuel mixture ratio test of the retained prototype. Figure 7 (a) The complete process of underwater injection (Case II). The camera starts at 0ms, and then oxygen and butane are introduced. At 125ms, the mixture in the combustion chamber is ignited and a flame appears. The injection starts at 125ms and ends at about 375ms. Figure 7 (b) Propulsion thrust curves at different mixing ratios from Case I to IV. The horizontal axis represents time (ms) and the vertical axis represents force (N). Figure 7 (c) Comparison of peak thrust and impulse under four conditions.

[0165] Figure 7 (a) is the jet process under Case II conditions. As shown in Table 2, in Case 1, the volume of butane is 20 mL, the volume of oxygen is 130 mL, and the mixing ratio is 1:6.5, which is the optimal mixing ratio for complete reaction. The camera starts to collect images from 0 ms, and the gas supply system starts. After 80 ms of servo rotation time, oxygen and butane enter the water tank, and then the mixed gas is ignited. Due to the use of a transparent tube, the violent flame produced by the explosion reaction can be clearly observed. At this time, the pressure in the water tank rises sharply, and water sprays out of the pipe. From Figure 6 From the force curve of Case II in (b), it can be seen that the jet force rises to a peak value between 125ms and 275ms. After 275ms, the amount of water in the water tank decreases and the high-pressure gas escapes. At this time, the jet turns into a water-gas jet. Since the mass of gas is much smaller than the mass of water, the thrust drops sharply. Finally, at 375ms, most of the water and gas in the combustion chamber are ejected and the thrust returns to zero.

[0166] Depend on Figure 7(c) It can be observed that when the mixing ratio is 1:6.5, the thrust reaches a maximum value of 80.27N and the total impulse reaches a maximum value of 9.2N·s. Obviously, the closer the ratio of oxygen to butane is to the ideal mixing ratio, the greater the thrust and total impulse can be obtained. The thrust attenuation is greater when the mixing ratio decreases (oxygen-deficient state) than when the mixing ratio increases (oxygen-rich state). When the oxygen content is 20mL different from the ideal state (Case II), the thrust attenuation of Case III (oxygen volume 150mL) is 32.7%, while the thrust attenuation of Case I (oxygen volume 110mL) is 57.6%. This is due to the higher molecular density and more active reaction in the oxygen-rich state. According to our tests, the mixing ratio less than Case I (1:5.5) and greater than Case IV (1:8.5) did not cause explosions, so we believe that these two ratios are the upper and lower safety limits for the normal operation of the thruster.

[0167] In BLS, the prototype generates more thrust, allowing it to clear taller obstacles. In OES, the prototype's attitude stabilizes at lower thrust, making it easier to control when combined with other propulsion systems, such as propellers.

[0168] Figure 8 Cameras captured the motion of the prototype during launch on the surface and underwater. Figure 8 (a) Detail of the thruster jet. B. Motion trajectory of the prototype at launch angles of 35°, 55°, and 65°. Figure 8 (b) Comparison of speed, angle, and altitude for three launch angles at two fuel ratios.

[0169] The flight trajectory and jet trajectory of the prototype in the surface launch experiment are as follows: Figure 8 (a). By capturing the rigid body information of the prototype through the motion capture system, we pay attention to the changes in the flight altitude, speed, and pitch angle of the prototype. The curves of speed, pitch angle, and altitude are shown in the figure below when the initial angle is set to three different angles (35°, 55°, and 65°) under two different mixing ratios of BLS and OES. Figure 8 As shown in (b), the end time of the data is the time when the prototype exceeds the detection range of the motion capture system. The aircraft can complete the transition from water exit to level flight attitude within 0-300ms. From the fuel mixture ratio experiment of the tethered prototype, it can be seen that the propulsion provided by OES is less than that of BLS. Therefore, at the same angle, the speed and maximum height of the prototype in the BLS state are greater than those of OES. Since the pitch angle is mainly affected by gravity, the pitch angle changes of the two are similar.

[0170] Among the three different launch angles, the speed is the smallest at an angle of 35°. We believe that this is because the angle between the prototype and the water surface decreases, and the speed at which the prototype completely leaves the water surface becomes faster. The horizontal plane of the fluid in the cavity is affected by gravity and gradually becomes perpendicular to the tail nozzle. In the jet stage, the form of water-air mixed jet dominates, and the propulsion loss increases.

[0171] By controlling the oxygen content and the initial launch angle, we can control the height and speed of the prototype leaving the water surface, thereby achieving attitude control.

[0172] The propeller used in the water-air amphibious vehicle proposed in this application is driven by the explosion reaction of bicomponent fuel butane and oxygen, which can complete the precise supply of gas within 100ms and can continuously carry out cross-media propulsion. The propeller has been designed and tested, integrated into the prototype of the water-air amphibious cross-media vehicle for experiments, and successfully demonstrated the ability to seamlessly transition between water and land environments. The use of butane as fuel improves the stability and efficiency of self-carrying gas source vehicles; the non-sensing form greatly shortens the time for gas replenishment with a simple mechanical structure and gas path design while reducing the weight of the propulsion system; we have established a theoretical analysis model and proved through experimental results that the propulsion system weighing 137g can generate a peak thrust of up to 80.2N. At the same time, by controlling the dual variables of fuel mixture ratio and launch angle, the peak force and duration of jet propulsion are changed, so that the flight attitude of the aircraft can be controlled. This propeller design provides an amphibious cross-media vehicle with a high explosive force propulsion scheme that can be precisely controlled, making the movement of the water-air amphibious cross-media vehicle across different media of water and air through jets analyzable and predictable.

[0173] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A method for avoiding obstacles for an amphibious vehicle, characterized in that: The obstacle avoidance method for the water-air amphibious vehicle comprises: Obtain the total impulse that can be provided by the propeller of the water-air amphibious vehicle; Obtain basic information about obstacles, basic information about the current time point of the water-air amphibious vehicle, and information about the time when butane and oxygen are filled into the mixing chamber; Obtaining the optimal water exit angle and the optimal water exit distance according to the basic information of the obstacle, the time information of butane and oxygen filling into the mixing chamber, and the basic information of the water-air amphibious vehicle at the current time point; The ventilation time point and the ignition time point are obtained according to the basic information of the obstacle and the time information of butane and oxygen filling into the mixing chamber; Controlling the butane gas supply system and the oxygen supply system to inflate the reaction chamber according to the ventilation time point; Ignition is performed in the reaction chamber according to the ignition timing, so that the water-air amphibious vehicle obtains the total impulse.

2. The obstacle avoidance method for an amphibious vehicle according to claim 1, characterized in that: The water-air amphibious vehicle obstacle avoidance method further comprises: The propeller is started when the preset position of the water-air amphibious vehicle flies out of the water.

3. The obstacle avoidance method for an amphibious vehicle as claimed in claim 2, characterized in that: The basic obstacle information includes the distance information between the obstacle and the amphibious aircraft, the position information of the obstacle relative to the amphibious aircraft, and the height information of the obstacle; The basic information of the amphibious water-air vehicle at the current time point includes the pitch attitude angle at the current time point, the current position coordinates of the amphibious water-air vehicle, the vehicle mass information, and the moment of inertia of the vehicle around the z-axis.

4. The obstacle avoidance method for an amphibious vehicle as claimed in claim 3, characterized in that: The total impulse that can be provided by the propeller of the water-air amphibious vehicle is obtained by the following formula: in, J(C) is the total impulse that the propeller of the amphibious vehicle can provide, C is the fuel concentration, when C=1, the system undergoes a stoichiometric reaction, when C<1, it is in an oxygen-rich state, at the end of the reaction, there is excess oxygen, which inhibits the production of by-products and reduces the risk of flashback. The value of C determines the degree of reaction activity, thereby affecting the generation of explosive reaction propulsion, t is the duration of propulsion, T jet The jet propulsion force.

5. The obstacle avoidance method for an amphibious vehicle as claimed in claim 4, characterized in that: The obtaining of the optimal water exit angle and the optimal water exit distance according to the basic information of the obstacle, the time information of butane and oxygen filling into the mixing chamber, and the basic information of the water-air amphibious vehicle at the current time point includes: Acquire a water outlet angle and navigation track database, wherein the water outlet angle and navigation track database includes at least one preset water outlet angle and navigation track information corresponding to each preset water outlet angle; According to the distance information between the obstacle and the amphibious vehicle and the time information of butane and oxygen being filled into the mixing chamber in the basic information of the obstacle, the distance information between the obstacle and the amphibious vehicle after butane and oxygen are filled into the mixing chamber is obtained, and the distance information between the obstacle and the amphibious vehicle after butane and oxygen are filled into the mixing chamber is called the first distance information; The optimal water-outlet angle and the optimal water-outlet distance are obtained according to the first distance information, the height information of the obstacle and each navigation trajectory information.

6. The obstacle avoidance method for an amphibious vehicle as claimed in claim 5, characterized in that: The obtaining of the optimal water-outlet angle and the optimal water-outlet distance according to the first distance information, the height information of the obstacle and each navigation track information comprises: Obtain time constraints, highest point trajectory height constraints, power transition smoothness constraints, and water surface separation angle constraints; Acquire navigation trajectory information that simultaneously satisfies the time constraint condition, the highest point trajectory height constraint condition, the power transition smoothness constraint condition, and the water surface separation angle constraint condition; When there is only one navigation track information that satisfies the time constraint, the highest point trajectory height constraint, the power transition smoothness constraint, and the water surface separation angle constraint, obtaining the water exit angle corresponding to the navigation track information as the optimal water exit angle; The walking distance between the initial point of the navigation track information and the highest point of the navigation track information is obtained as the optimal water outlet distance.

7. The obstacle avoidance method for an amphibious vehicle as claimed in claim 6, characterized in that: The time constraints include: t peak ≥t prop in, t prop is the propeller acceleration time, t peak is the time required for the vehicle to reach the highest point of the obstacle from the water surface, and the linear growth rate of the propeller thrust is k p .

8. The obstacle avoidance method for an amphibious vehicle as claimed in claim 7, characterized in that: The highest point trajectory height constraint conditions include: in, The power transition smoothness constraint conditions include: in, α max is the maximum allowed rate of pitch angle change, which is used to avoid instability caused by drastic attitude adjustments; The water surface departure angle constraint conditions include: φ min ≤φ0≥φ max ;in, φ min and φ max Determined based on specific mission requirements and thruster limitation angles.

9. A water-air amphibious vehicle, characterized in that: The water-air amphibious vehicle comprises: Aircraft hull; A propeller, one end of which extends into the shell of the aircraft, a mixing chamber is provided in the propeller, the mixing chamber comprises a butane air inlet, an oxygen air inlet, a pressure liquid injection port, and a liquid injection port, the mixing chamber contains liquid, the pressure liquid injection port is located at the end of the propeller away from the shell of the aircraft, and an ignition device is provided in the mixing chamber; a butane gas supply system, the butane gas supply system being disposed in the aircraft shell and being in communication with the butane gas inlet for providing pressurized butane gas into the mixing chamber; An oxygen supply system, the oxygen supply system is arranged in the aircraft shell, the oxygen supply system is connected to the oxygen inlet, and is used to provide pressurized oxygen to the mixing chamber; wherein, When the pressurized butane gas and pressurized oxygen enter the mixing chamber and the pressure in the mixing chamber reaches a preset threshold, ignition is performed through an ignition device, so that the pressurized butane gas and pressurized oxygen in the mixing chamber explode to generate thrust for expelling liquid from the pressurized liquid injection port.

10. The water-air amphibious vehicle according to claim 9, characterized in that: The water-air amphibious vehicle further comprises: a propeller, the propeller being arranged on the aircraft hull; A propeller driving system is disposed in the aircraft shell and connected to the propeller to drive the propeller to rotate.

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