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

Abstract

The application discloses a water-air amphibious vehicle obstacle avoidance method and a water-air amphibious vehicle. The water-air amphibious vehicle obstacle avoidance method comprises the following steps: acquiring a total impulse that can be provided by a propeller of the water-air amphibious vehicle; acquiring basic information of an obstacle, basic information of the water-air amphibious vehicle at a current time point, and time information of filling of butane and oxygen into a mixing cavity; acquiring an optimal water exit angle and an optimal water exit distance; acquiring a ventilation time point and an ignition time point according to the basic information of the obstacle and the time information of filling of butane and oxygen into the mixing cavity; controlling a butane gas supply system and an oxygen supply system to fill gas into a reaction cavity according to the ventilation time point; and igniting in the reaction cavity according to the ignition time point, so that the water-air amphibious vehicle obtains the total impulse. The application designs a water-air amphibious vehicle obstacle avoidance method, and fills the gap that the prior art cannot avoid obstacles through water-air medium conversion.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicle technology, in particular to a water-air amphibious vehicle obstacle avoidance method and a water-air amphibious vehicle. BACKGROUND

[0002] With the continuous development of multi-modal vehicle research, water-air amphibious cross-medium vehicles are gradually becoming a new direction of human research and development of marine equipment. For example, 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 the air and underwater working scenes, thereby avoiding underwater and air obstacles. When high-speed travel is needed to reach the destination, the vehicle can enter the air for low-power long-time navigation; when underwater operation is needed, 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 sea rescue, ocean sample collection, and ocean archaeology, without the need for large ships or unmanned aerial vehicles. This has broad application prospects in future ocean exploration. Figure 1 The medium density of water is 700 times different from that of the air, so the design of the power system is crucial to the realization of the vehicle crossing the water into the air. A type of vehicle uses a brushless motor to drive a propeller to realize medium crossing, but the propeller needs to be constantly accelerated to generate enough propulsion to pull the vehicle out of the water surface, and the two-phase crossing time is long.

[0003] The propeller form continues the design concept of the aerial vehicle, which reduces the research and development difficulty in control method and structure design, but also faces the inherent problem of cavitation and cavitation of the propeller underwater. Inspired by the flying squid in nature, which can quickly escape from the ocean to the air through muscle compression jet, a part of the research begins to propose the use of jet propulsion to realize water-air crossing.

[0004] Jet propulsion has the characteristics of generating high momentum in a short time, and is a high-energy density release propulsion form. The prototype using this type of propulsion can escape from the water body at a faster speed.

[0005] However, the water-air amphibious vehicle of the prior art only realizes pure driving in water and pure flight in the air, and how to use the advantages of water-air amphibious to avoid obstacles in water is not considered in the prior art.

[0006] SUMMARY The purpose of the present application is to provide a water-air amphibious vehicle obstacle avoidance method to at least solve one of the above technical problems.

[0007] One aspect of the present application provides a water-air amphibious vehicle obstacle avoidance method, the water-air amphibious vehicle obstacle avoidance method comprising:

[0008]

[0009] ​Obtaining total impulse provided by the propeller of the water-air amphibious vehicle;

[0010] Obtaining basic information of the obstacle and basic information of the water-air amphibious vehicle at the current time point, and time information of filling the mixed cavity with butane and oxygen;

[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 filling the mixed cavity with butane and oxygen, and the basic information of the water-air amphibious vehicle at the current time point;

[0012] Obtaining the time point of aeration and the time point of ignition according to the basic information of the obstacle and the time information of filling the mixed cavity with butane and oxygen;

[0013] Controlling the butane gas supply system and the oxygen supply system to fill the reaction cavity with gas according to the time point of aeration;

[0014] Igniting in the reaction cavity according to the time point of ignition, so that the water-air amphibious vehicle obtains the total impulse.

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

[0016] Starting the propeller when the water-air amphibious vehicle flies out of the water at a preset position.

[0017] Optionally, the basic information of the obstacle comprises distance information of the obstacle from the water-air amphibious vehicle, position information of the obstacle relative to the water-air amphibious vehicle, and height information of the obstacle.

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

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

[0020] ; wherein,

[0021] The total impulse provided by the propeller of the water-air amphibious vehicle, C is the fuel concentration, when C=1, the system undergoes stoichiometric reaction, when C<1, it is an oxygen-rich state, at the end of the reaction, oxygen is excessive, which inhibits the generation of by-products and reduces the risk of backfire, the value of C determines the degree of reaction activity, thereby affecting the generation of explosion reaction thrust, t is the duration of the thrust, The jet propulsion force.

[0022] Optionally, the obtaining the optimal water-exit angle and the optimal water-exit distance according to the obstacle basic information, the butane and oxygen filling time information of the mixing cavity, and the current time point basic information of the amphibious vehicle includes:

[0023] obtaining a water-exit angle and a navigation trajectory database, the water-exit angle and the navigation trajectory database including at least one preset water-exit angle and navigation trajectory information corresponding to each preset water-exit angle;

[0024] obtaining distance information between the obstacle and the amphibious vehicle after butane and oxygen are filled into the mixing cavity according to the distance information between the obstacle and the amphibious vehicle in the obstacle basic information and the butane and oxygen filling time information, the distance information between the obstacle and the amphibious vehicle after butane and oxygen are filled into the mixing cavity being referred to as first distance information;

[0025] obtaining the optimal water-exit angle and the optimal water-exit distance according to the first distance information, the height information of the obstacle, and each navigation trajectory information.

[0026] Optionally, the obtaining the optimal water-exit angle and the optimal water-exit distance according to the first distance information, the height information of the obstacle, and each navigation trajectory information includes:

[0027] obtaining a time constraint condition, a highest point trajectory height constraint condition, a power transition smoothness constraint condition, and a water surface departure angle constraint condition;

[0028] obtaining 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 departure angle constraint condition;

[0029] when the 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 departure angle constraint condition is only one, obtaining a water-exit angle corresponding to the navigation trajectory information as the optimal water-exit angle;

[0030] obtaining a walking distance between an initial point of the navigation trajectory information and a highest point of the navigation trajectory information as the optimal water-exit distance.

[0031] Optionally, the time constraint condition includes:

[0032] ; wherein,

[0033] is an acceleration time, is a time required for the vehicle to move from the water surface to the highest point of the obstacle, and a linear growth rate of the propeller thrust force is .

[0034] Optionally, the highest point trajectory height constraint condition comprises:

[0035] wherein,

[0036] The power transition smoothness constraint condition comprises:

[0037] wherein,

[0038] is the maximum pitch angle change rate allowed, which avoids instability caused by drastic attitude adjustment;

[0039] The water surface departure angle constraint condition comprises:

[0040] wherein,

[0041] and is determined based on specific task requirements and the limited angle of the propeller.

[0042] The application also provides a water-air amphibious vehicle, comprising:

[0043] a vehicle shell;

[0044] a propeller, one end of which extends into the vehicle shell, wherein a mixing chamber is arranged in the propeller, the mixing chamber comprises a butane gas inlet, an oxygen gas inlet, a pressure liquid injection port, and a liquid filling port, the mixing chamber contains liquid, the pressure liquid injection port is located at the end of the propeller away from the vehicle shell, and an ignition device is arranged in the mixing chamber;

[0045] a butane gas supply system arranged in the vehicle shell, which is in communication with the butane gas inlet and is used to provide pressure butane gas into the mixing chamber;

[0046] an oxygen supply system arranged in the vehicle shell, which is in communication with the oxygen gas inlet and is used to provide pressure oxygen into the mixing chamber; wherein,

[0047] when the pressure butane gas and the pressure oxygen enter into the mixing chamber and the pressure in the mixing chamber reaches a preset threshold, the ignition device is ignited, so that the pressure butane gas and the pressure oxygen in the mixing chamber explode to generate thrust for expelling the liquid from the pressure liquid injection port.

[0048] Optionally, the water-air amphibious vehicle further comprises:

[0049] a propeller disposed on the vehicle housing;

[0050] a propeller drive system disposed within the vehicle housing, the propeller drive system connected to the propeller for driving the propeller in rotation.

[0051] Advantages

[0052] The water-air amphibious vehicle obstacle avoidance method designed in the application proposes a joint control strategy of the fuel explosion jet propulsion system and the propeller propulsion system, breaking through the bottleneck that the existing single propulsion technology is poor in rapidity and sustainability in the water-air medium conversion process and cannot effectively realize obstacle avoidance. Traditional amphibious vehicles often face different control challenges in underwater and air environments. The application constructs a system with air movement capability and water-air shuttle capability, and proposes an obstacle avoidance method that can cope with underwater and air obstacles at the same time through a unique control strategy. In the underwater stage, the vehicle only needs to pay attention to the height of the obstacle. After spraying the water surface, the fuel explosion jet propulsion can quickly generate strong propulsion, pushing the vehicle to break through the water surface, and driving the propeller system within the time interval calculated by the algorithm, to ensure that the vehicle can obtain sufficient and continuous propulsion, and stably enter the level flight attitude. In the air stage, the propeller propulsion continues to maintain the stability of the vehicle and provides continuous power for it. The innovation of this method lies in that by jointly controlling the jet propulsion and the propeller propulsion, not only the problem that the single propulsion system in the traditional technology cannot meet the propulsion demand in underwater and air is solved, but also efficient obstacle avoidance in the water-air conversion process is realized. After spraying on the water surface, the vehicle can quickly respond to environmental changes and connect the propeller system propulsion to move away from the obstacle, ensuring the safety of the vehicle. This scheme can break through the water surface at high speed when water-air shuttling, and can take advantage of the propeller in the air, thereby effectively improving the maneuverability, stability and ability to adapt to complex environments of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 is a flowchart of the water-air amphibious vehicle obstacle avoidance method of an embodiment of the application.

[0054] Figure 2 is a structural schematic diagram of the water-air amphibious vehicle in an embodiment of the application.

[0055] Figure 3 is a schematic diagram of the water-air amphibious vehicle in an embodiment of the application converting from the water medium to the air medium.

[0056] Figure 4 is an electronic system and gas control circuit schematic diagram of the water-air amphibious vehicle in an embodiment of the application.

[0057] Figure 5is a schematic diagram of a leap obstacle of a water-air amphibious vehicle in an embodiment of the present application.

[0058] Figure 6 is a schematic diagram of a structure of a six-dimensional force platform in an embodiment of the present application.

[0059] Figure 7 is a schematic diagram of experimental results of a tethered prototype fuel mixing ratio in an embodiment of the present application.

[0060] Figure 8 is a schematic diagram of a water surface launch transition to an air attitude change in an embodiment of the present application.

[0061] Reference signs:

[0062] 1, propeller; 2, vehicle shell. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiments of the present application will be described in more detail below in combination with the drawings in the embodiments of the present application. In the drawings, the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some embodiments of the present application, not all embodiments. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. The embodiments of the present application will be described in detail below in combination with the drawings.

[0064] As shown in the water-air amphibious vehicle obstacle avoidance method includes: Figure 1

[0065] Step 1: obtaining the total impulse that can be provided by the propeller of the water-air amphibious vehicle;

[0066] Step 2: obtaining the basic information of the obstacle and the basic information of the water-air amphibious vehicle at the current time point, and the time information of filling the mixing chamber with butane and oxygen;

[0067] Step 3: obtaining the optimal water exit angle and the optimal water exit distance according to the basic information of the obstacle, the time information of filling the mixing chamber with butane and oxygen, and the basic information of the water-air amphibious vehicle at the current time point;

[0068] Step 4: obtaining the ventilation time point and the ignition time point according to the basic information of the obstacle and the time information of filling the mixing chamber with butane and oxygen;

[0069] Step 5: controlling the butane gas supply system and the oxygen supply system to fill the reaction chamber according to the ventilation time point.​

[0070] Step 6: Ignition is performed at the reaction cavity according to the ignition time point, so that the water-air amphibious vehicle obtains the total impulse.

[0071] The application designs a water-air amphibious vehicle obstacle avoidance method, fills the gap that the prior art cannot avoid obstacles through water-air medium conversion, and only needs to consider the height of the obstacle to realize the determination of the control scheme of the underwater and air parts when underwater, and directly drives the propeller to rotate after being ejected out of the water surface.

[0072] In this embodiment, the water-air amphibious vehicle obstacle avoidance method further comprises:

[0073] The propeller is started when the water-air amphibious vehicle flies out of the water surface at a preset position. It can be understood that the position information can be obtained by attaching a depth sensor to the surface of the vehicle at a preset position.

[0074] In this embodiment, the obstacle basic information includes distance information of the obstacle from the water-air amphibious vehicle, position information of the obstacle relative to the water-air amphibious vehicle, and obstacle height information.

[0075] The water-air amphibious vehicle current time point basic information includes current time point pitch attitude angle, water-air amphibious vehicle current position coordinates, vehicle mass information, and vehicle moment of inertia around the z axis.

[0076] In this embodiment, the total impulse that the propeller of the water-air amphibious vehicle can provide is obtained by the following formula:

[0077] ; wherein,

[0078] The total impulse that the propeller of the water-air amphibious vehicle can provide, C is the fuel concentration, when C=1, the system undergoes stoichiometric reaction, when C<1, it is oxygen-rich state, at the end of the reaction, oxygen is excessive, which inhibits the generation of by-products and reduces the risk of tempering, the value of C determines the activity of the reaction, thereby affecting the generation of explosion reaction thrust, t is the duration of the thrust, The relationship function of the thrust and the time, the fuel concentration.

[0079] In this embodiment, The total impulse that the propeller of the water-air amphibious vehicle can provide is obtained by the following formula:

[0080] ; wherein,

[0081] To promote the force peak and fuel concentration relationship function, the peak of the thrust pulse can be determined by fitting through experiments. The fuel concentration C and the chemical reaction rate k jointly determine the duration of the thrust pulse, and b is the time offset, is the density of water, and the value is equal to , is the diameter of the tail nozzle, and π is the circular constant.

[0082] In the embodiment, the optimal water exit angle and the optimal water exit distance are obtained according to the obstacle basic information, the butane and oxygen filling time information of the mixing chamber, and the current time point basic information of the water-air amphibious vehicle.

[0083] The water exit angle and the navigation trajectory database are obtained, and the water exit angle and the navigation trajectory database include at least one preset water exit angle and navigation trajectory information corresponding to each preset water exit angle. In the embodiment, the navigation trajectory information includes the movement trajectory of the water-air amphibious vehicle according to different angles after ignition in the mixing chamber, and specifically, the navigation trajectory information includes the position relationship of the water-air amphibious vehicle at each time point. For example, at the 0-second time point, that is, when the gas in the mixing chamber has not been ignited, the initial position of the water-air amphibious vehicle is assumed to be (x1, y1), and after ignition in the mixing chamber, the positions at different time points are different, for example, at the 1-second time point, the position may be (x2, y2).

[0084] The distance information between the obstacle and the water-air amphibious vehicle after butane and oxygen are filled into the mixing chamber is obtained according to the distance information between the obstacle and the water-air amphibious vehicle in the obstacle basic information and the butane and oxygen filling time information of the mixing chamber, and the distance information between the obstacle and the water-air amphibious vehicle after butane and oxygen are filled into the mixing chamber is called the first distance information.

[0085] The optimal water exit angle and the optimal water exit distance are obtained according to the first distance information, the height information of the obstacle, and each navigation trajectory information.

[0086] In the embodiment, the optimal water exit angle and the optimal water exit distance are obtained according to the first distance information, the height information of the obstacle, and each navigation trajectory information, and the method includes the following steps.

[0087] 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 are obtained, and the 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 is obtained.

[0088] 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 choose 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.

[0089] 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.

[0090] In this embodiment, the navigation track information can be obtained by the following formula:

[0091] The propulsion force provided by the gas explosion in the mixing chamber of the present application At time To time Acting on the water-air amphibious vehicle, the lever arm is , the speed of the water-air amphibious vehicle changes from the initial speed Upgrade to .

[0092] According to the moment balance, the angular acceleration of the pitch angle change can be expressed as:

[0093]

[0094] in, 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.

[0095] The amphibious vehicle is under force balance, subject to gravity G and buoyancy , water resistance and propulsion The acceleration changes in the x and z directions of the vehicle can be obtained by:

[0096] The equation of motion is:

[0097]

[0098] Through the above formula, the theoretical position information of the amphibious vehicle per second when underwater can be obtained, thereby obtaining the navigation trajectory information of the underwater section of the present application.

[0099] When the amphibious vehicle of the present application is out of water but the propeller has not yet started, the navigation trajectory information of the present application can be obtained by the following formula:

[0100] The propeller does not provide thrust at this stage, the vehicle is subjected to gradually decreasing buoyancy, gravity and air resistance, the initial velocity is the velocity at the end of the underwater acceleration stage, and the position is the point of emergence.

[0101] The acceleration of the vehicle in the x and z directions varies as:

[0102]

[0103] where, is the instantaneous velocity of the vehicle, is the projected area of the vehicle, is the wetted surface area of the vehicle, which is related to the size of the vehicle; is the pressure drag coefficient, which depends on the shape of the vehicle and the fluid separation condition; is the friction drag coefficient, which is determined by the Reynolds number (which can be calculated according to an empirical formula or a flat plate flow approximation); is the volume of the part of the vehicle submerged in water to generate buoyancy. Similarly, the motion trajectory can be obtained by numerical method after integration .

[0104] The pitch angle is defined by a nonlinear second-order differential equation.

[0105]

[0106] By numerical method, under the condition of inertia dominance, the equation can be simplified to obtain:

[0107]

[0108] where, , d is the moment of gravity and aerodynamic center force. , is the time factor of the change of the pitch angle.

[0109] Through the above formula, the theoretical position information of the water-air amphibious vehicle per second can be obtained when the water-air amphibious vehicle of the application emerges from the water but the propeller has not started yet, so as to obtain the navigation trajectory information of the water-air amphibious vehicle of the application in the stage of emergence from the water but the propeller has not started yet.

[0110] When the propeller of the water-air amphibious vehicle of the application can provide lift, the navigation trajectory information of the application can be obtained by the following formula:

[0111] Propeller starts to convert to level flight attitude

[0112] 1. Propeller thrust

[0113]

[0114] 2. Pitch variation

[0115] The pitch angle variation is derived by total moment,

[0116]

[0117] Where Mp, Mg and Ma are the moments of propeller thrust, gravity and air drag respectively.

[0118] 3. Horizontal component

[0119]

[0120] Vertical component

[0121]

[0122] The trajectory equation is obtained by integrating the horizontal and vertical components and the pitch variation .

[0123] In this embodiment, the time constraint includes:

[0124] ; wherein,

[0125] is the propeller acceleration time, 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 .

[0126] In this embodiment, the highest point trajectory height constraint includes:

[0127] ; wherein,

[0128] The power transition smoothness constraint includes:

[0129] ; wherein,

[0130] is the maximum allowable pitch angle variation rate, which avoids instability caused by drastic attitude adjustment, and the value can be adjusted according to the dynamic characteristics (mass, pitch moment, fluid resistance, etc.) of the vehicle, and is a constant value;

[0131] The water surface departure angle constraint includes:

[0132] ; wherein,

[0133] and are determined based on specific task requirements and the limited angle of the propeller.

[0134] The application also provides a water-air amphibious vehicle, characterized in that the water-air amphibious vehicle comprises a vehicle shell 2, a propeller 1, a butane gas supply system and an oxygen supply system, wherein,

[0135] The propeller 2 extends into the vehicle shell 1 at one end, and a mixing chamber is arranged in the propeller 2, the mixing chamber comprises a butane gas inlet, an oxygen gas inlet, a pressure liquid injection port and a liquid filling port, the mixing chamber contains liquid, the pressure liquid injection port is located at the end of the propeller away from the vehicle shell, and an ignition device is arranged in the mixing chamber;

[0136] The butane gas supply system is arranged in the vehicle shell, is communicated with the butane gas inlet and is used for providing pressure butane gas into the mixing chamber;

[0137] The oxygen supply system is arranged in the vehicle shell, is communicated with the oxygen gas inlet and is used for providing pressure oxygen into the mixing chamber; wherein,

[0138] When the pressure butane gas and the pressure oxygen enter into the mixing chamber and the pressure in the mixing chamber reaches a preset threshold value, the ignition device is ignited, so that the pressure butane gas and the pressure oxygen in the mixing chamber explode to generate a thrust for discharging the liquid from the pressure liquid injection port.

[0139] The water-air amphibious vehicle of the application further comprises a propeller and a propeller driving system, wherein,

[0140] The propeller is arranged on the vehicle shell;

[0141] The propeller driving system is arranged in the vehicle shell, is connected with the propeller and is used for driving the propeller to rotate.

[0142] In one embodiment, the propeller prototype of the application comprises a gas supply system (a butane gas supply system, an oxygen supply system), a propeller and an electric control system. The main body of the propeller is an aluminum alloy pipe 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 of an explosion reaction. The aluminum alloy pipe is made by metal 3D printing.

[0143] In order to reduce the water resistance and prevent the elements from being wetted, the vehicle shell adopts a von Karman cone shape at the head based on maintaining the fixed wing shape of the prototype, the vehicle shell is a revolving body coaxial with the water tank, the electric control system is fastened with the water pipe through a sealing ring and is separated from water. The material of the wing is polystyrene foam, which is cut to form.

[0144] 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 upper middle part of the prototype. Due to the coaxial design, the distribution of components can be easily adjusted by moving forward and backward and rotating, and the center of gravity can be changed. The center of gravity is located behind the center of buoyancy, so it can have a positive pitch angle underwater. The components are concentrated at the top of the prototype, and the space reserved at the bottom can bear other loads, such as sensors, cameras, etc.

[0145] In order to perfectly complete the water-air crossing, the thruster needs to generate a large thrust in a short time. We chose the combination of butane and oxygen as the source of reaction. The huge energy generated by their explosion reaction can generate enough reaction force to push the prototype out of the water.

[0146] The explosion limit of butane in air is 1.5%-8.5%, so a precise gas supply system needs to be considered first. The oxygen supply system (total weight 86g) includes a servo, a connecting disc (PLA material), a pressure reducing valve, and an oxygen tank. By controlling the angle and duration of the twisted pressure reducing valve with a motor, the gas supply can be accurately controlled. We chose a butane gas cylinder for the butane gas supply system (total weight 51 g), which can release butane gas by pressing the connecting button (PLA material) at the top. This device is also controlled by a 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.

[0147] The electronic system and gas control circuit of the amphibious vehicle are shown in Figure 4 We chose ATmega 328P chip as the microcontroller, which can meet the control requirements of the servo and the relay. A 2S Li-Po battery provides 7.4V power for the servo, and then a step-down chip reduces it to 5V to power the microcontroller and micro relay. The prototype receives commands through a 433Mhz wireless transparent module. 433Mhz is a low-frequency signal that can be effectively transmitted within a distance of 2m underwater, so it can support us to remotely control the actions of the prototype underwater.

[0148] The fuel gas supply process is shown in Figure 4The bottom half shows. First, butane is introduced, and the rudder is rotated from the initial angle to the end position. Our test results show that the volume of butane gas increases linearly in the 5-80ms press time range, and can be accurately controlled in the 20-80mL range. Liquid butane is converted to gas at normal pressure, enters the water pipe through the gas path in the button, and enters the water pipe through the one-way valve. The process takes an average of 5-10ms. The oxygen gas path is opened by controlling the valve opening angle and opening time, and can stably provide more than 6 times 130mL of oxygen (depending on the oxygen content in the bottle) within 75ms-100ms. After all the gas is introduced, the water level decreases from 450mL to 300mL. Finally, a 5V voltage is input to the high-voltage generator through a relay, a high-temperature arc is formed at the metal tip, and the mixed combustible gas in the pipe is ignited to produce a jet.

[0149] The application also provides a propulsion force test method, the propulsion force test method of the application comprises:

[0150] A six-dimensional force measurement platform was built to test the propulsion force and momentum generated by butane and oxygen at different mixing ratios to explore the gas fuel dosage corresponding to the maximum propulsion force. The force measurement platform includes a water tank (2m×1m×1m), an aluminum profile fixed frame, a force sensor (1000Hz), a connecting clamp, a test prototype (stainless steel, containing 600mL of water). The test prototype is fixed below the frame and connected to the slider. The slider can translate to convert the propulsion force into pressure and transmit it to the force sensor. The same amount of water (400mL) is controlled, 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.

[0151] Table 1 Physical parameter settings for mixing ratio experiments

[0152]

[0153] In order to explore the different pose changes generated by the prototype when launched at different angles from the water surface, we arranged a scene as shown in Figure 6 (b) shows the scene, including 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 the fixed frame. The pose information of the prototype is obtained by capturing the information of four markers pasted on the surface of the prototype by the motion capture system. The specific experimental settings are shown in Table 2.

[0154] Table 2 Physical parameter settings for each experiment below

[0155]

[0156] Figure 7 is the fuel mixing ratio experimental result of the prototype. Figure 7(a) The whole process of underwater jet (Case II). The camera starts at 0 ms, then oxygen and butane are introduced. At 125 ms, the mixture in the combustion chamber is ignited, the flame appears, the jet starts at 125 ms and ends at about 375 ms. Figure 7 (b) Propulsion thrust curves under different mixture 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 cases.

[0157] Figure 6 (a) The jet process under Case II conditions. As shown in Table 2, the volume of butane in Case I is 20 mL, the volume of oxygen is 130 mL, and the mixture ratio is 1:6.5, which is the optimal mixture ratio for complete reaction. The camera starts image acquisition at 0 ms, the gas supply system starts, and 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 intense flame produced by the explosion reaction can be clearly observed. At this time, the pressure in the water tank rises sharply, and water is ejected from the pipe. From Figure 7 (b) The force curve of Case II can be seen that the jet force rises to a peak at about 125 ms to 275 ms. After 275 ms, the water in the water tank decreases, and the high-pressure gas escapes. At this time, the jet changes into a water-gas jet. Because the mass of gas is much smaller than the mass of water, the thrust drops sharply, and finally at 375 ms, most of the water and gas in the combustion chamber are ejected, and the thrust returns to zero.

[0158] From Figure 8 (c) Observation shows that the propulsion force reaches a maximum of 80.27 N when the mixture ratio is 1:6.5, and the total impulse reaches a maximum of 9.2 N·s. It is obvious that the closer the ratio of oxygen to butane is to the ideal mixture ratio, the greater the propulsion force and total impulse can be obtained. The degree of propulsion force decay is greater when the mixture ratio decreases (oxygen deficiency) than when the mixture ratio increases (oxygen enrichment). In the case where the oxygen content is 20 mL different from the ideal state (Case II), the propulsion force of Case III (oxygen volume 150 mL) decays by 32.7%, while the propulsion force of Case I (oxygen volume 110 mL) decays by 57.6%. This is due to the higher molecular density and more active reaction in the oxygen-rich state. Through our tests, mixture ratios less than Case I (1:5.5) and greater than Case IV (1:8.5) do not cause explosions, so we consider these two ratios to be the upper and lower limits of the safe operation of the thruster.

[0159] In BLS, the prototype generates more thrust, enabling it to overcome higher 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.

[0160] Figure 8 Camera-captured motion trajectory of the prototype in water and underwater launch. Figure 8 (a) Propeller injector details. B. Motion trajectory of the prototype at launch angles of 35°, 55°, and 65°. Figure 8 (b) Comparison of speed, angle, and height at three launch angles under two fuel ratios.

[0161] Prototype flight trajectory and jet trajectory in surface launch experiment as Figure 8 (a). By capturing the rigid body information of the prototype through the motion capture system, we focus on the changes in the flight height, speed, and pitch angle of the prototype. Under two different mixing ratios of BLS and OES, the speed, pitch angle, and height curves at three different initial angles (35°, 55°, 65°) are shown in ​ (b). The data cutoff time is when the prototype exceeds the detection range of the motion capture system. The vehicle can complete the transition from water to level flight attitude within 0-300ms. From the fuel mixing ratio experiment of the tethered prototype, we know that the propulsion provided by OES is smaller than that of BLS, so at the same angle, the speed and maximum height of the prototype in BLS state are greater than those in OES. Since the pitch angle is mainly affected by gravity, the pitch angle changes of the two are close.

[0162] 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 increases. The fluid level in the cavity is affected by gravity and gradually becomes perpendicular to the tail nozzle. In the jet stage, the water-gas mixed jet dominates, and the loss of thrust becomes larger.

[0163] By controlling the oxygen content and the initial launch angle, we can control the height at which the prototype leaves the water surface and the speed at which it leaves the water surface, thereby achieving attitude control.

[0164] The propeller used by the amphibious vehicle proposed in the application is driven by the explosion reaction of two-component fuel butane and oxygen, can complete the accurate supply of gas within 100 ms, and can continuously carry out cross-medium propulsion. The propeller has completed design and testing, is integrated in a water-air amphibious cross-medium vehicle prototype for experiment, successfully demonstrates the ability of seamless transition in water and land environments. Butane is used as fuel, which improves the stability and efficiency of self-carrying gas source type vehicles; the non-sensing form reduces the weight of the propulsion system while greatly shortening the gas supplement time with simple mechanical structure and gas path design; a theoretical analysis model is established, and the experimental results prove that the propulsion system with a weight of 137 g can generate a peak thrust of up to 80.2 N. At the same time, through the control of fuel mixing ratio and launch angle as double variables, the peak force and duration of jet propulsion are changed, so as to control the flight attitude of the vehicle. The propeller provides a high-explosive force propulsion scheme that can be accurately controlled for amphibious cross-medium vehicles, making the movement of the amphibious cross-medium vehicle across different media of water-air by jet have analyzability and predictability.

[0165] Although the present application has been described in detail with general description and specific embodiments above, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of protection claimed by the present application.

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 amphibious vehicle, and information about the time when butane and oxygen are filled into the mixing chamber; Obtaining an optimal water exit angle and an optimal water exit distance based on 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 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 amphibious vehicle obtains the total impulse; 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 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; obtaining, based on the distance information between the obstacle and the amphibious vehicle and the time information of filling the mixing chamber with butane and oxygen, the distance information between the obstacle and the amphibious vehicle after the butane and oxygen are filled into the mixing chamber in the basic obstacle information, wherein the distance information between the obstacle and the amphibious vehicle after the butane and oxygen are filled into the mixing chamber is referred to as first distance information; Obtaining an optimal water exit angle and an optimal water exit distance according to the first distance information, the height information of the obstacle, and each navigation track information; 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 includes: Acquisition time constraints, highest point trajectory height constraints, power transition smoothness constraints, and water surface separation angle constraints; Obtaining navigation trajectory information that simultaneously satisfies the time constraint, the highest point trajectory height constraint, the power transition smoothness constraint, and the water surface separation angle constraint; 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, obtaining the water exit angle corresponding to the navigation trajectory information as the optimal water exit angle; Obtaining the travel distance between the initial point of the navigation track information and the highest point of the navigation track information as the optimal water exit distance; The time constraints include: ;in, is the propeller acceleration time, is the time required for the vehicle to move from the water surface to the highest point of the obstacle, and the linear growth rate of the propeller propulsion force is ; The highest point trajectory height constraint conditions include: ； The power transition smoothness constraint conditions include: ;in, 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: ;in, and Determined based on specific mission requirements and thruster limiting angles.

2. The obstacle avoidance method for an amphibious vehicle according to claim 1, wherein: The obstacle avoidance method for the water-air amphibious vehicle 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 according to claim 2, wherein: The basic obstacle information includes the distance between the obstacle and the amphibious vehicle, the position of the obstacle relative to the amphibious vehicle, and the height of the obstacle. The basic information of the amphibious vehicle at the current time point includes the pitch attitude angle at the current time point, the current position coordinates of the amphibious 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 according to claim 3, wherein: The total impulse that can be provided by the propeller of the amphibious vehicle is obtained by the following formula: ;in, is the total impulse that the propulsion system 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 force. t is the duration of propulsion force. Jet propulsion force.

5. An amphibious vehicle, applicable to the amphibious vehicle obstacle avoidance method according to claims 1 to 4, characterized in that: The water-air amphibious vehicle comprises: Aircraft hull; a propeller, one end of the propeller extending into the aircraft shell, a mixing chamber provided in the propeller, the mixing chamber including a butane air inlet, an oxygen air inlet, a pressure liquid injection port, and a liquid injection port, the mixing chamber containing liquid, the pressure liquid injection port being located at an end of the propeller away from the aircraft shell, and an ignition device being provided in the mixing chamber; a butane gas supply system, the butane gas supply system being disposed within the aircraft housing and communicating with the butane gas inlet for providing pressurized butane gas to the mixing chamber; An oxygen supply system is provided in the aircraft shell and is in communication with the oxygen inlet for providing 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 by an ignition device, so that the pressurized butane gas and pressurized oxygen in the mixing chamber explode to generate thrust for expelling the liquid from the pressurized liquid injection port.

6. The amphibious vehicle according to claim 5, characterized in that: The water-air amphibious vehicle further comprises: a propeller, the propeller being arranged on the aircraft hull; A propeller drive system is provided in the aircraft shell and is connected to the propeller for driving the propeller to rotate.

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