An eVTOL aircraft parachute safety system with active trigger mechanism

Abstract

The application discloses a kind of eVTOL aircraft parachute safety systems with active trigger mechanism, it is related to flight landing equipment technical field, the system includes umbrella package module, quick release module, umbrella opening trigger module, deployment induction module, impact slow-release module and attitude stability and tension control module;For electric vertical take-off and landing aircraft in emergency or emergency state Safety slow descent protection, with artificial command control and automatic fault recognition dual trigger mechanism as the core of parachute, can be triggered by artificial or system automatic trigger to complete umbrella body deployment in the critical situation such as aircraft out of control, power interruption, significantly reduce the impact load in the early stage of deployment and maintain the attitude stability during descent process.The system has the characteristics of fast response, compact structure, slow-release adjustable, strong adaptability, etc., and is suitable for the safe landing requirements of eVTOL aircraft in low-altitude operation in emergency situations such as loss of control or power failure.

Description

Technical Field

[0001] This invention relates to the field of flight landing equipment technology, and more specifically to an eVTOL aircraft parachute safety system with an active triggering mechanism. Background Technology

[0002] In recent years, electric vertical takeoff and landing (eVTOL) aircraft, as an important platform for urban low-altitude transportation and short-range transport, are gradually moving towards commercial application. Due to their generally low flight altitude, rapid speed changes, and compact structure, eVTOLs face more stringent safety challenges when operating in complex urban airspace. Especially in emergency situations such as power failure, thruster failure, or loss of flight attitude control, eVTOL aircraft typically lack gliding capabilities and cushioning structures, making them highly susceptible to crashes and seriously threatening the lives and property of passengers and ground personnel.

[0003] Traditional aircraft parachute systems mostly employ a passive triggering method, relying on gravity to deploy the parachute when the aircraft loses altitude or power. This type of design typically cannot react promptly when the aircraft is still at high speed or in an unstable attitude. Typical problems include delayed deployment timing, severe impact loads, difficulty in attitude control, and poor adaptability. For example, during high-speed descent, a sudden inflation of a traditional parachute can easily trigger instantaneous overload, leading to structural damage or even secondary accidents. Furthermore, existing systems often rely on a single altitude or power failure signal to determine emergency situations, lacking a comprehensive understanding of multi-dimensional flight conditions such as attitude, speed, and acceleration.

[0004] Especially in the practical application of eVTOL aircraft, traditional parachute solutions are insufficient in terms of deployment speed, release method, and attitude stability. Therefore, there is an urgent need for a parachute system that can be actively triggered, precisely controlled, and has adaptive adjustment capabilities to improve the descent stability and safety redundancy of eVTOL under extreme conditions. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an eVTOL aircraft parachute safety system with an active triggering mechanism.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This application discloses an eVTOL aircraft parachute safety system with an active triggering mechanism, including:

[0008] The parachute module includes a main parachute and a sub-parachute. The main parachute is located at the top of the aircraft or at a position symmetrical to the center of gravity. The sub-parachute is located in the front end area of ​​the main parachute. It is released before the main parachute unfolds and is guided by tension to detach from and unfold the main parachute pack.

[0009] The quick-release module includes a mechanical locking unit and an active drive unit. The mechanical locking unit includes a spring pin, a locking plate, and a reset assembly, which is used to restrict the deployment of the parachute module in the closed state. The active drive unit is triggered by the power release module and the main control unit to release the sub-parachute and unlock the main parachute.

[0010] The parachute deployment trigger module, integrated in the main control unit, includes a manual triggering circuit and a fault state perception triggering circuit. The manual triggering circuit receives manual commands from the flight control system or ground personnel. The fault state perception triggering circuit judges state variables through multi-source sensors. When the state variables meet the dangerous state combination logic, the fault state perception triggering circuit triggers a control pulse signal, which activates the rapid release device through the main control unit.

[0011] The deployment guidance module includes a slide rail guide groove and a directional stabilizer. After the sub-parachute is released, the main parachute is guided and pulled in the slide rail guide groove by an induction belt to ensure that the main parachute deploys in the design order in the guidance path. During the inflation process, it is completed under the action of aerodynamics, and the directional stabilizer ensures that the canopies of the main parachute and the sub-parachute are subjected to symmetrical forces.

[0012] The impact relief module includes an elastic relief cable, a nonlinear damping unit, and a metal energy dissipation component. The elastic relief cable is used to alleviate the tensile force impact in the initial opening stage of the main umbrella and the sub-umbrella. If the impact velocity exceeds the set threshold of the elastic relief cable, the nonlinear damping unit provides velocity-related drag. If the impact energy is still not completely absorbed, the metal energy dissipation component performs controlled yield absorption of the peak energy.

[0013] The attitude stabilization and tension control module includes a multi-point attachment device, a tension sensing unit, and a pulley system. During descent, the main parachute and the aircraft maintain attitude balance through the multi-point attachment device. The tension sensing unit and pulley system are located at the attachment points. The tension sensing unit monitors the tension of each parachute line, and the main control unit sends control commands to control the pulley system to dynamically adjust the length and tension of the corresponding parachute lines, ensuring the stability of the aircraft's attitude.

[0014] Furthermore, the set threshold for the elastic sustained-release cord includes: via the formula Calculate the wind resistance of the aircraft after the main parachute is inflated. ,in Indicates the umbrella drag coefficient. Indicates air density, and A represents the effective windward area of ​​the umbrella. This represents the instantaneous vertical velocity upon parachute opening, followed by the calculated wind resistance. The upper limit of the parachute rope tension during the process of the main parachute going from inflation to full deployment is predicted, and the threshold of the elastic release cable and the throttling parameter of the parachute opening are set by the predicted upper limit of tension.

[0015] Preferably, providing speed-related resistance through a nonlinear damping unit includes: relating the release stroke to the speed-related resistance level using a formula. The mapping is performed, where the deceleration distance from parachute deployment to velocity stabilization is denoted as... The initial vertical velocity is , This represents the average deceleration.

[0016] Preferably, the impact mitigation module further includes a longitudinal deceleration dynamic model, which is used to predict the peak impact value and stopping distance during rolling, and to adjust the umbrella opening, damping coefficient, or mitigation stroke in real time. The formula for the umbrella opening deceleration period is as follows: Where m represents the total mass of the spacecraft, and g represents the acceleration due to gravity. For the velocity-related drag of the impact-controlled release module, This represents vertical acceleration.

[0017] Preferably, in the attitude stabilization and tension control module: let the left and right tensions be respectively... and The equivalent arm is Under small-angle, quasi-static approximation, the formula can be used to... Characterizing attitude offset, where The deflection angle is represented by , and k represents the equivalent constant related to the aircraft's moment of inertia and geometric stiffness.

[0018] Preferably, peak energy is absorbed by controlled yielding using a metal energy-dissipating component. satisfy ,in Represents the initial kinetic energy. This indicates the energy absorption ratio.

[0019] Preferably, the umbrella opening trigger module (3) is configured with an active trigger function that has multiple variable thresholds. When the result of the actively triggered function Greater than the preset threshold Or when an irreversible failure of the propulsion system is detected, i.e. This triggers an active parachute deployment path and integrates the "paddle stop - sub-parachute - main parachute - slow release" process; among which... This represents the Heaviside function, where h represents the height. This represents the minimum height. Weights representing height This indicates the maximum vertical velocity. Indicates vertical velocity. The weight representing the vertical velocity, Indicates acceleration. This indicates the maximum acceleration. The weights representing acceleration, The weight of the total thrust is indicated by T, which represents the total thrust. This represents the minimum total thrust.

[0020] Preferably, it also includes a delay triggering module, which is used to precisely control the deployment sequence of the sub-umbrella and the main umbrella, ensuring that the sub-umbrella and the main umbrella work sequentially according to a predetermined rhythm.

[0021] The beneficial effects of this invention are:

[0022] 1) This system supports dual-channel active triggering, including manual triggering and flight status triggering. During aircraft operation, if there is a loss of thrust, power interruption, attitude instability, or if the operator determines that the parachute needs to be deployed, the main control unit can control the parachute deployment trigger module to initiate deployment.

[0023] 2) The entire system has the structural characteristics of fast response, smooth release and good attitude control, and is particularly suitable for emergency descent protection of eVTOL in urban low-altitude and high-frequency operation scenarios.

[0024] 3) This invention uses a parachute system with structure drive as its core, combined with an active triggering device and a slow-release control component, to achieve closed-loop control of the entire process from command recognition, parachute release, deployment, slow release to attitude control, ensuring that the aircraft has reliable and efficient slow-descent capabilities when encountering various extreme conditions, and maximizing the safety of equipment and personnel. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of an eVTOL aircraft parachute safety system with an active triggering mechanism according to an embodiment of the present invention.

[0026] In the diagram, 1-parachute pack module, 11-sub-parachute, 12-main parachute, 2-quick release module, 21-mechanical locking unit, 22-active drive unit, 3-parachute opening trigger module, 31-main control unit, 4-deployment guidance module, 41-slide rail guide, 42-directional stabilizer, 5-impact mitigation module, 51-elastic mitigation cable, 52-metal energy dissipation component, 6-attitude stabilization and tension control module, 61-multi-point attachment device. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] eVTOL (electronic vertical takeoff and landing), hovering, and horizontal cruise are flight platforms that rely on electric propulsion systems to achieve vertical takeoff and landing, hovering, and horizontal cruise. They are widely used in urban air traffic, short-haul transportation, air medical rescue, and logistics delivery. eVTOLs typically operate in low-altitude airspace, where the operating altitude is low, the environment is complex, and gliding ability is poor. Therefore, in the event of loss of control, power outage, or propulsion system failure, a reliable emergency descent system is urgently needed to ensure structural integrity and personnel safety. This invention proposes an eVTOL parachute system with an active triggering mechanism, focusing on improving the emergency release capability of low-altitude aircraft in dangerous situations such as sudden loss of control, power failure, or structural abnormalities. It addresses the problems of existing parachute devices, such as strong passivity, delayed deployment, poor release performance, and structural incompatibility, thereby enhancing the aircraft's descent protection capability throughout the entire flight phase. A schematic diagram of the system is shown below. Figure 1 As shown. Specifically includes:

[0029] The parachute module 1 includes a main parachute 12 and a sub-parachute 11. The main parachute 12 is located on the top of the aircraft or at a position symmetrical to the center of gravity. The main parachute 12 is made of a high-temperature resistant composite material parachute shell, and its parachute lines and canopy are made of high-strength aramid fiber. The sub-parachute 11 is located in the front end area of ​​the main parachute 12. It is released before the main parachute 12 unfolds and guides the parachute pack of the main parachute 12 to detach and unfold through tension.

[0030] The quick-release module 2 includes a mechanical locking unit 21 and an active drive unit 22. The mechanical locking unit 21 includes a spring pin, a locking plate, and a reset assembly, which is used to restrict the deployment of the parachute module in the closed state. The active drive unit 22 is triggered by the power release module and the main control unit 31 to release the sub-parachute 11 and unlock the main parachute 12. The power release module can be a pyrotechnic bolt or a high-pressure gas jet.

[0031] The parachute deployment trigger module 3, integrated in the main control unit 31, includes a manual triggering circuit and a fault state perception triggering circuit. The manual triggering circuit receives manual commands from the flight control system or ground personnel. The fault state perception triggering circuit determines state variables through multi-source sensors, including flight altitude, speed, attitude, thrust, etc. When the combination logic of dangerous states is met, the fault state perception triggering circuit triggers a control pulse signal, which activates the rapid release device through the main control unit. The parachute deployment trigger module 3 also has a redundancy protection and delayed confirmation mechanism.

[0032] The deployment induction module 4 includes a slide rail guide groove 41 and a directional stabilizer 42. After the sub-umbrella 11 is released, the main umbrella 12 is guided and pulled in the slide rail guide groove 41 by an induction belt to ensure that the main umbrella 12 unfolds in the design sequence in the induction path. During the inflation process, it is completed under the action of aerodynamics, and the directional stabilizer 42 ensures that the canopies of the main umbrella 12 and the sub-umbrella 11 are symmetrically stressed.

[0033] The impact mitigation module 5 includes an elastic mitigation cable 51, a nonlinear damping unit, and a metal energy dissipation component 52. The elastic mitigation cable 51 is used to mitigate tensile force impact during the initial opening of the main umbrella 12 and the sub-umbrella 11. If the impact velocity exceeds the set threshold of the elastic mitigation cable 51, the nonlinear damping unit provides velocity-related resistance. The nonlinear damping unit can be, for example, a hydraulic cylinder or a friction disc, to provide velocity-related resistance. If the impact energy is still not completely absorbed, the metal energy dissipation component 52 performs controlled yield absorption of the peak energy. The parameters of this module are adjustable to match eVTOL platforms of different masses.

[0034] The attitude stabilization and tension control module 6 includes a multi-point attachment device 61, a tension sensing unit, and a pulley system. During descent, the main parachute 12 and the aircraft maintain attitude balance through the multi-point attachment device 61. The tension sensing unit and pulley system are located at the attachment points. The tension sensing unit monitors the tension of each parachute line and sends control commands through the main control unit 31 to control the pulley system to dynamically adjust the length and tension of the corresponding parachute lines. This balances the tension difference between the left, right, and tail sections in real time, preventing roll, yaw, or tilt, and ensuring the stability of the aircraft's attitude. When necessary, it can be used in conjunction with local canopy vents to dynamically adjust the lift distribution.

[0035] For example, the set threshold of the elastic sustained-release cord 51 includes: by formula Calculate the wind resistance of the aircraft after the main parachute 12 is inflated. ,in This indicates the umbrella's drag coefficient (which is related to the umbrella shape and materials). Indicates air density, and A represents the effective windward area of ​​the umbrella. This represents the instantaneous vertical velocity upon parachute opening, followed by the calculated wind resistance. The upper limit of the parachute rope tension during the process of the main umbrella 12 from inflation to full deployment is predicted, and the threshold of the elastic release cable 51 and the throttling parameter of the umbrella opening are set by the predicted upper limit of tension.

[0036] For example, providing speed-related resistance through a nonlinear damping unit includes: relating the release stroke to the speed-related resistance level using a formula. A mapping is performed to ensure structural and occupant safety margins, where the deceleration distance from parachute deployment to speed stabilization is denoted as... The initial vertical velocity is , This represents the average deceleration.

[0037] For example, the impact mitigation module 5 also includes a longitudinal deceleration dynamic model. This model is used to predict the peak impact value and stopping distance during rolling, and to adjust the umbrella opening, damping coefficient, or mitigation stroke in real time. The formula for the umbrella opening deceleration period is as follows: Where m represents the total mass of the spacecraft, and g represents the acceleration due to gravity. For the velocity-related drag of the impact-controlled release module, This represents vertical acceleration.

[0038] For example, in the attitude stabilization and tension control module 6: uneven tension on the parachute lines after opening will introduce pitch / roll deviation. Let the left and right tensions be respectively... and The equivalent arm is Under small-angle, quasi-static approximation, the formula can be used to... Characterizing attitude offset, where The deflection angle is represented by , and k represents an equivalent constant related to the aircraft's moment of inertia and geometric stiffness. The deflection is suppressed by adjusting the left and right tension difference and the opening of local vents (or control plates). The growth of the parachute helps to prevent the parachute lines from becoming tangled and the parachute from becoming unsteady.

[0039] Exemplarily, peak energy is absorbed by controlled yielding via metal energy dissipation component 52. satisfy ,in Represents the initial kinetic energy. It indicates the energy absorption ratio, which is used to coordinate the division of labor between elastic cables, hydraulic / friction damping and metal energy dissipation components, reduce peak overload and constrain deceleration within the range that the structure and occupants can bear.

[0040] For example, the umbrella opening trigger module 3 has an active trigger function with a multi-variable threshold. When the result of the actively triggered function Greater than the preset threshold Or when an irreversible failure of the propulsion system is detected, i.e. This triggers an active parachute deployment path and integrates the "paddle stop - sub-parachute - main parachute - slow release" process; among which... This represents the Heaviside function, where h represents the height. This represents the minimum height. Weights representing height This indicates the maximum vertical velocity. Indicates vertical velocity. The weight representing the vertical velocity, Indicates acceleration. This indicates the maximum acceleration. The weights representing acceleration, The weight of the total thrust is indicated by T, which represents the total thrust. This represents the minimum total thrust.

[0041] For example, the system also includes a delay triggering module, which is used to precisely control the deployment sequence of the sub-umbrella 11 and the main umbrella 12, ensuring that the sub-umbrella 11 and the main umbrella 12 work sequentially according to a predetermined rhythm. After the system determines that the main umbrella 12 needs to be deployed, the delay triggering module introduces a preset time delay (e.g., 8 seconds) to ensure that the sub-umbrella 11 has enough time to complete the construction of the guide channel, creating stable conditions for the pull-out and deployment of the main umbrella 12. This "sub-umbrella first, then main umbrella" tiered deployment strategy is key to reducing the impact force of opening the umbrella. By controlling the slow deployment action of the main umbrella 12, the overload caused by the instantaneous full opening of the main umbrella 12 is avoided, improving comfort and safety.

[0042] Exemplarily, this invention is applicable to situations where an aircraft experiences sudden events such as loss of control, power interruption, or structural damage under various flight conditions, achieving autonomous descent and stable landing through a structural linkage mechanism. The core system process includes: flight status identification → active trigger signal output → propeller shutdown → parachute deployment → energy absorption control → attitude adjustment and stabilization → safe ground contact. After filtering the trigger signal, the explosive bolt or high-pressure gas jet is driven to unlock the rapid release module. The sub-parachute 11 deploys first under the action of the elastic mechanism, guiding the induction belt to deploy, and the main parachute 12 opens sequentially, with airflow entering the canopy to complete inflation. The main parachute 12 deployment process takes approximately 0.3 to 0.8 seconds. The impact mitigation module 5 intervenes before the peak tension to reduce the instantaneous load on the system. The multi-point attachment device 61 begins to dynamically adjust the tension to achieve a slow descent. The following describes the working process and mutual cooperation of each structural module of the system according to six typical flight conditions.

[0043] For example, during vertical takeoff, eVTOL aircraft typically fly at a low altitude and with a slow ascent rate. If problems such as motor power failure, power system malfunction, or takeoff control lock-up occur, they will face the risk of crashing within a very short time. When a fault occurs, the fault state perception trigger circuit first collects the current altitude, vertical velocity, and acceleration values, and determines whether the thrust has suddenly dropped below the safety threshold. If it is determined to be "ascent out of control," the parachute deployment trigger module 3 will immediately send a stop command to the propeller control unit, prioritizing the elimination of interference from the high-speed rotor on the deployment path. Subsequently, the parachute deployment trigger module 3 sends an electrical signal to the rapid release module 2. If the power release module is an explosive bolt structure, its micro pyrotechnic unit, after being activated, will fix the explosive hatch bolts, causing the parachute shell to open rapidly; if the power release module is a high-pressure gas structure, it will release compressed gas through a solenoid valve, pushing the piston to drive the release locking mechanism to open, completing the initial release of the parachute. The main parachute 12 rapidly unfolds along the ascending direction under the traction of the guide belt of the sub-parachute 11, and the fabric automatically inflates and forms its shape. Simultaneously, the impact mitigation module 5 enters the initial response phase: the high-modulus elastic parachute lines undergo finite elongation, controlling the rate of tension increase. Subsequently, the nonlinear damping unit outputs drag to counteract the instantaneous load caused by the sudden change in speed. During deployment, the multi-point attachment device 61 connects each rope to the load-bearing points of the main structure of the aircraft. Under the action of the downward torque, the aircraft automatically converts to a vertical attitude. If any deviation exists, the attitude stabilization and tension control modules 6 on both sides of the parachute lines will automatically adjust according to the tension difference to suppress pitch or roll deviation. Finally, the aircraft completes ground contact in a balanced and slow manner, with its head up and feet down.

[0044] For example, during level flight, in the medium-to-high speed level cruise phase, eVTOL faces various potential malfunctions such as wind disturbance, propulsion system failure, and navigation loss of control. Once high horizontal speed, lack of thrust feedback, or abnormal attitude changes are detected, the system triggers an active parachute deployment process. First, the parachute deployment trigger module 3 identifies the fault state and outputs a deployment signal, the propeller stops rotating, and then the sub-parachute 11 is released. The sub-parachute 11 is pulled by guide lines, preferentially leaving the engine wake area, forming a stable airflow channel before pulling the main parachute 12 detach from the parachute pack. The main parachute 12 unfolds under the influence of inertia and airflow, employing a multi-fold compression fabric structure that stretches layer by layer during opening. At this time, the impact mitigation module enters the "medium-damping working section," where the elastic parachute lines gradually release their stretching stroke, cooperating with the hydraulic damper to output adaptive impedance according to speed, preventing secondary impacts on the aircraft from sudden tension changes. Attitude stability depends on the distribution of the main parachute attachment points and the establishment of symmetrical tension. When the aircraft yaws or becomes unbalanced, the tension adjustment mechanism of the left and right parachute lines automatically balances through elastic differences. If necessary, small ventilation holes can be opened at the edge of the parachute to reduce lateral forces and ensure that the aircraft enters a stable descent trajectory.

[0045] For example, in hovering mode, if a sudden strong wind, insufficient thrust, or flight control failure occurs, the system is highly susceptible to losing stationary control. In this situation, the system quickly determines the aircraft's position based on attitude changes (roll rate, pitch angle) and remaining thrust. Once hovering loss of control is confirmed, the propellers are immediately stopped and parachute deployment is initiated. To meet the requirement of rapid deployment at low altitudes, the system directly releases the main parachute 12 and simultaneously deploys the secondary parachute for assisted orientation, with the structural deployment aiming for "rapid tensioning." In this scenario, the impact mitigation module 5 uses high-rigidity, short-stroke rigging and friction dampers to prioritize establishing a high-tension state and prevent tension from failing to form at insufficient altitude. Since hovering often occurs in low-altitude urban airspace, the canopy fabric uses highly expandable fibers to improve inflation efficiency and ensure rapid establishment of the complete canopy shape. During deployment, since the aircraft itself does not acquire sufficient inertia, the stabilizing axis formed by the parachute lines becomes the only source of balance. Multi-point attachment and parachute line pre-tensioning design ensure the aircraft is passively aligned and automatically descends vertically under the influence of the tension field.

[0046] For example, the ultra-low altitude state (altitude <100 meters) is suitable for operational platforms such as instant logistics, urban inspection, and light-load drones. The flight environment is complex and the space is extremely small, requiring extremely high reaction speed. In this state, the system is configured with a "zero-delay parachute opening path." Once a fault is detected (such as power failure, gyroscope drift, or GPS loss of lock), the threshold judgment will be skipped, and the parachute opening command will be output directly. The main parachute 12 unfolds using a high-pressure gas jet actuator in the power release module. The gas released from the high-pressure CO2 cylinder pushes the metal arm to pry open the parachute pack, instantly ejecting the parachute body. The main parachute directly completes a short-range explosive unfolding through a structural folding pre-tensioning mechanism. The nonlinear damping unit of the impact mitigation module 5 uses rigid buffers, such as graphite rubber damping blocks or unequal-length tension cables, to control the upper limit of deceleration. In this scenario, the landing time is extremely short, and the structural actions need to complete the entire process of parachute release, fabric expansion, and tension establishment within 0.8 seconds, realizing a compact three-stage action chain of "instantaneous-deceleration-descent".

[0047] For example, in the low-altitude upper-level state (100–1000 meters), this is applied to medium-speed platforms such as eVTOL for express delivery and short-haul logistics in urban routes. The moderate flight altitude allows for threshold assessment and structural deployment mitigation control. When the state recognition module confirms that the aircraft is in an uncontrollable state (such as battery thermal runaway, control surface jamming, or program freeze), the system executes the following sequentially: propeller stop → parachute deployment → main parachute release → mitigation structure activation. The main parachute deploys layer by layer after being pulled by the parachutes, and the elastic mitigation cable 51 enters the "mid-range stroke" working segment. The elastic mitigation cable 51 and the nonlinear damping unit work together to output a nonlinear tension curve. The structural component arrangement allows the tension to rise smoothly to its full value within 1–2 seconds, with the peak deceleration controlled within 3g. This altitude range also supports the "left and right parachute line angle fine-tuning" function in the attitude stabilization and tension control module 6. By fine-tuning the rope distribution through the multi-point attachment device 61 and pulley system, a slow pitch adjustment action is formed, enhancing the aircraft's directional control capability during descent.

[0048] For example, the low-altitude upper-level state (1000–3000 meters) is mostly used for long-range, manned eVTOL flight platforms, which can withstand longer response delays and have tiered structural deployment. After fault judgment is determined by the manual triggering circuit and the fault state perception triggering circuit, the sub-parachute 11 first completes the construction of the guidance channel, and then the main parachute 12 performs the slow deployment action. During this process, the release mechanism adopts a "delay triggering module", and the release rhythm is controlled by a pyrotechnic delay tube or an electromagnetic delayer. The parachute deployment enters a "multi-stage slow release" structural program. First, the primary slow release stage provides flexibility to establish tension. During this process, the nonlinear damping unit adopts a hydraulic structure. The hydraulic damping enters the main energy dissipation stage, and finally, the parachute tension difference correction stage completes the attitude leveling. The entire process lasts no more than 2 seconds to achieve a lower final contact impact and meet the occupant safety standards. The main parachute has a larger deployment area, and the impact slow release module is redundantly configured with more levels of limit devices and force control units. During the slow deceleration at high altitude, it completes the entire process of automatic attitude leveling, multiple speed reductions, and soft landing at the descent terminal.

[0049] In summary, this application discloses an eVTOL aircraft parachute safety system with an active triggering mechanism. Centered on a parachute, it features a dual triggering mechanism of manual command control and automatic fault identification, enabling parachute deployment by human intervention or automatic system activation in emergency situations such as aircraft loss of control or power outage. The system includes a parachute pack module 1, a rapid release module 2, a parachute deployment triggering module 3, a deployment induction module 4, an impact mitigation module 5, and an attitude stabilization and tension control module 6. The parachute is rapidly released and deployed via explosive bolts or a high-pressure gas-driven device. Combined with an elastic mitigation cable 51, a nonlinear damping unit, and multi-point tension control, it significantly reduces the impact load during initial deployment and maintains attitude stability during descent. It features rapid response, compact structure, adjustable mitigation, and strong adaptability, making it suitable for the safe landing needs of low-altitude eVTOL aircraft in emergency situations such as loss of control or power failure.

[0050] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A parachute safety system for an eVTOL aircraft with an active triggering mechanism, characterized in that, include: The parachute module (1) includes a main parachute (12) and a sub-parachute (11). The main parachute (12) is located on the top of the aircraft or at a position symmetrical to the center of gravity. The sub-parachute (11) is located in the front end area of ​​the main parachute (12). It is released before the main parachute (12) unfolds and the main parachute (12) is guided to detach and unfold by pulling force. The quick release module (2) includes a mechanical locking unit (21) and an active drive unit (22). The mechanical locking unit (21) includes a spring pin, a locking plate and a reset assembly, which are used to restrict the deployment of the umbrella module in the closed state. The active drive unit (22) is triggered by the power release module and the main control unit (31) to release the sub-umbrella (11) and unlock the main umbrella (12). The parachute opening trigger module (3) is integrated in the main control unit (31) and includes a manual triggering circuit and a fault state perception triggering circuit. The manual triggering circuit receives manual commands from the flight control system or ground personnel. The fault state perception triggering circuit judges the state variables through multi-source sensors. When the state variables meet the dangerous state combination logic, the fault state perception triggering circuit triggers the control pulse signal and starts the rapid release device through the main control unit. The deployment induction module (4) includes a slide rail guide groove (41) and a directional stabilizer (42). After the sub-umbrella (11) is released, the main umbrella (12) is guided and pulled in the slide rail guide groove (41) by an induction belt to ensure that the main umbrella (12) unfolds in the design sequence in the induction path. During the inflation process, it is completed under the action of aerodynamics. The directional stabilizer (42) ensures that the canopies of the main umbrella (12) and the sub-umbrella (11) are symmetrically stressed. The impact relief module (5) includes an elastic relief cable (51), a nonlinear damping unit and a metal energy dissipation component (52). The elastic relief cable (51) is used to alleviate the tensile force impact in the early stage of opening the main umbrella (12) and the sub-umbrella (11). If the impact speed exceeds the set threshold of the elastic relief cable (51), the nonlinear damping unit provides speed-related resistance. If the impact energy is not completely absorbed, the metal energy dissipation component (52) performs controllable yield absorption of peak energy. The attitude stabilization and tension control module (6) includes a multi-point attachment device (61), a tension sensing unit and a pulley system. During the landing process, the main parachute (12) and the aircraft maintain attitude balance through the multi-point attachment device (61). The tension sensing unit and the pulley system are set at the attachment points. The tension sensing unit monitors the tension of each parachute line and sends control commands through the main control unit (31) to control the pulley system to dynamically adjust the length and tension of the corresponding parachute line, thereby ensuring the stability of the aircraft's attitude.

2. The eVTOL aircraft parachute safety system with an active triggering mechanism according to claim 1, characterized in that, The set threshold for the elastic sustained-release cord (51) includes: by formula Calculate the wind resistance of the aircraft after the main parachute (12) is inflated. ,in Indicates the umbrella drag coefficient. Indicates air density, and A represents the effective windward area of ​​the umbrella. This represents the instantaneous vertical velocity upon parachute opening, followed by the calculated wind resistance. The upper limit of the parachute rope tension during the process of the main umbrella (12) from inflation to full deployment is predicted, and the threshold of the elastic release cable (51) and the throttling parameter of the umbrella opening are set by the predicted upper limit of tension.

3. The eVTOL aircraft parachute safety system with an active triggering mechanism according to claim 2, characterized in that, Providing speed-related resistance through a nonlinear damping unit includes: relating the release stroke to the speed-related resistance level using a formula. The mapping is performed, where the deceleration distance from parachute deployment to velocity stabilization is denoted as... The initial vertical velocity is , This represents the average deceleration.

4. The eVTOL aircraft parachute safety system with an active triggering mechanism according to claim 3, characterized in that, The impact mitigation module (5) also includes a longitudinal deceleration dynamic model, which is used to predict the impact peak and stopping distance during rolling, and to adjust the umbrella opening, damping coefficient, or mitigation stroke in real time. The formula for the umbrella opening deceleration period is as follows: Where m represents the total mass of the spacecraft, and g represents the acceleration due to gravity. For the velocity-related drag of the impact-controlled release module, This represents vertical acceleration.

5. A parachute safety system for an eVTOL aircraft with an active triggering mechanism according to claim 1, characterized in that, In the attitude stabilization and tension control module (6): let the left and right tensions be respectively and The equivalent arm is Under small-angle, quasi-static approximation, the formula can be used to... Characterizing attitude offset, where The deflection angle is represented by , and k represents the equivalent constant related to the aircraft's moment of inertia and geometric stiffness.

6. The eVTOL aircraft parachute safety system with an active triggering mechanism according to claim 1, characterized in that, Peak energy is absorbed by controlled yielding through a metal energy-dissipating component (52). satisfy ,in Represents the initial kinetic energy. This indicates the energy absorption ratio.

7. A parachute safety system for an eVTOL aircraft with an active triggering mechanism according to claim 1, characterized in that: The active triggering function with multi-variable thresholds is set in the umbrella opening triggering module (3). When the result of the actively triggered function Greater than the preset threshold Or when an irreversible failure of the propulsion system is detected, i.e. This triggers an active parachute deployment path and integrates the "paddle stop - sub-parachute - main parachute - slow release" process; among which... This represents the Heaviside function, where h represents the height. This represents the minimum height. Weights representing height This indicates the maximum vertical velocity. Indicates vertical velocity. The weight representing the vertical velocity, Indicates acceleration. This indicates the maximum acceleration. The weights representing acceleration, The weight of the total thrust is indicated by T, which represents the total thrust. This represents the minimum total thrust.

8. The eVTOL aircraft parachute safety system with an active triggering mechanism according to claim 1, characterized in that, It also includes a delay triggering module, which is used to precisely control the deployment sequence of the sub-umbrella (11) and the main umbrella (12) to ensure that the sub-umbrella (11) and the main umbrella (12) work in sequence according to a predetermined rhythm.

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