Vehicle door anti-collision method and system based on shape memory alloy

Abstract

The invention relates to a vehicle door anti-collision method and system based on shape memory alloy, and belongs to the field of vehicle safety. The method comprises the following steps: capturing a piezoelectric signal, triggering a multi-physics coupling monitoring process through the piezoelectric signal, and outputting a collision event and a collision type; based on the collision event and the collision type, activating a low phase transition temperature area and obtaining a target volume fraction, and dynamically adjusting deformation parameters to generate vehicle door deformation; deformation absorption energy is obtained, an active recovery amount is obtained based on the deformation absorption energy, vehicle door deformation is actively recovered, and the active recovery amount comprises a conventional recovery amount and a hyperelastic auxiliary recovery amount. According to the method, the monitoring precision is improved in combination with multi-physics field coupling analysis, active control over vehicle door deformation is achieved through dynamic volume fraction adjustment, and deformation is rapidly repaired through a thermal-mechanical cooperative recovery mechanism.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle safety, and particularly relates to a door anti-collision method and system based on shape memory alloy. Background Art

[0002] Traditional vehicle collision safety technologies mainly rely on the combination of mechanical crushable energy-absorbing structures (such as anti-collision beams and energy-absorbing boxes) and passive sensors (such as accelerometers and pressure sensors). In recent years, collision monitoring technologies based on piezoelectric materials have gradually emerged, which convert mechanical energy into electrical signals through the piezoelectric effect to achieve a rapid response to collision events. However, there are problems of insufficient monitoring accuracy and lack of multi-physical field coupling: traditional accelerometers are vulnerable to vibration interference and cannot accurately distinguish collision types (such as low-speed scraping and high-speed impact); existing systems only rely on a single physical quantity (such as pressure or temperature) to judge collision events, resulting in a high false judgment rate. In addition, shape memory alloys (SMA) and phase change materials (such as low melting point metals) are used for active deformation adjustment of energy-absorbing structures, but their applications are limited by insufficient response speed, energy consumption, and recovery ability. The mechanical crush structure is a one-time design and cannot dynamically adjust the energy-absorbing ability according to the collision intensity; shape memory alloys require continuous external energy supply and have a slow recovery speed, making it difficult to cope with multiple collision scenarios. Summary of the Invention

[0003] To solve the above problems existing in the prior art, the present invention provides a door anti-collision method and system based on shape memory alloy.

[0004] The object of the present invention can be achieved by the following technical solutions: A door anti-collision method based on shape memory alloy, the implementation of the door anti-collision method includes the following steps: S1: Capture piezoelectric signals, trigger a multi-physical field coupling monitoring process through the piezoelectric signals, and output collision events and collision types; S2: Activate the low phase change temperature region based on the collision event and the collision type and obtain the target volume fraction, and dynamically adjust the deformation parameters to generate door deformation; S3: Obtain the deformation absorption energy, obtain the active recovery amount based on the deformation absorption energy, and actively recover the door deformation. The active recovery amount includes a conventional recovery amount and a superelastic assisted recovery amount.

[0005] Preferably, the step S1 specifically includes: S101: Capture the piezoelectric signals and convert them into an output voltage. When the output voltage exceeds a set threshold, trigger the multi-physical field coupling monitoring process; S102: Obtain the cross-sectional area of the pressure fiber, and convert the output voltage into a pressure value based on the cross-sectional area of the pressure fiber; S103: Obtain the temperature rise and resistance change at the collision point, and output the coupling monitoring parameter through a data fusion algorithm based on the pressure value; S104: Output the collision event based on the coupling monitoring parameter. The collision event includes a valid collision event and an invalid collision event. Set a preset coupling monitoring parameter threshold. When the coupling monitoring parameter is greater than or equal to the coupling monitoring parameter threshold, it is determined as the valid collision event, otherwise it is determined as the invalid collision event; S105: Establish a collision feature database based on the output voltage and pulse width, and classify the collision type using a convolutional neural network.

[0006] Preferably, the mathematical description of the pressure value is , where F is the pressure value, d 33 is the piezoelectric constant, A is the cross-sectional area of the pressure fiber, G is the amplifier gain coefficient, and V is the output voltage.

[0007] Preferably, the mathematical description of the coupling detection parameter is , where S(t) is the coupling monitoring parameter, ω1, ω2, and ω3 are weights, F max is the ultimate compressive strength of the material, △R is the resistance change, △T is the temperature rise, △R max is the resistance change corresponding to the maximum allowable tensile amount of the wire, and △T max is the maximum temperature rise allowed by the system.

[0008] Preferably, the step S2 specifically includes: S201: When the valid collision event is output, energize the collision point and obtain the energized temperature; S202: When the energized temperature does not reach the preset phase change temperature, increase the energizing voltage. If it is still insufficient, activate the adjacent area for auxiliary heating; when the energized temperature reaches the phase change temperature, activate the low phase change temperature area; S203: Set the target volume fraction according to the collision type, and dynamically adjust the deformation parameter according to the phase change kinetics equation.

[0009] Preferably, the mathematical description of the energized temperature is , where T0 is the temperature before energization, V T is the energizing voltage, R is the real-time resistance, ρ is the material density, c is the specific heat capacity, α is the thermal diffusivity, is the geometric factor, (x, y) is the energization point coordinate, and (x0, y0) is the collision point coordinate.

[0010] Preferably, the mathematical description of the phase change kinetics equation is , where, is the volume fraction, A0 is the kinetic coefficient, is the actual stress, is the critical stress, S is the saturation stress, Q is the activation energy, and U is the gas constant.

[0011] Preferably, the obtaining of the conventional recovery amount in step S3 specifically includes: Obtain the original length of the door anti-collision beam and heat the collision point to obtain the recovery temperature, and obtain the conventional recovery amount based on the original length of the door anti-collision beam and the recovery temperature. The mathematical description is , where is the conventional recovery amount, is the coefficient of thermal expansion, is the recovery temperature, and L0 is the original length of the door anti-collision beam.

[0012] Preferably, the obtaining of the superelastic assisted recovery amount in step S3 specifically includes: Apply a mechanical pre-tightening force, and obtain the superelastic assisted recovery amount based on the energy absorbed by the deformation and the mechanical pre-tightening force. The mathematical description is , where is the superelastic assisted recovery amount, is the superelastic recovery factor, is the mechanical pre-tightening force, and E is the energy absorbed by the deformation.

[0013] A door anti-collision system based on shape memory alloy for performing the above-mentioned door anti-collision method, including a coupling monitoring module, a door deformation module, and a deformation recovery module; The coupling monitoring module is used to capture piezoelectric signals, trigger a multi-physical field coupling monitoring process through the piezoelectric signals, and output collision events and collision types; The door deformation module is used to activate the low phase transition temperature region based on the collision event and the collision type and obtain the target volume fraction, and dynamically adjust the deformation parameters to generate door deformation; The deformation recovery module is used to obtain the energy absorbed by the deformation, obtain the active recovery amount based on the energy absorbed by the deformation, and actively recover the door deformation. The active recovery amount includes the conventional recovery amount and the superelastic assisted recovery amount.

[0014] The beneficial effects of the present invention are: (1) High-precision collision recognition: By fusing multi-dimensional data of pressure, temperature, and resistance, the misjudgment rate is significantly reduced.

[0015] (2) Active recovery ability: Overcome the problems that the mechanical collapse structure cannot dynamically adjust the energy absorption ability according to the collision intensity, and the shape memory alloy requires external continuous power supply and has a slow recovery speed, making it difficult to handle multiple collision scenarios, and can be used repeatedly. Description of the Drawings

[0016] For the convenience of those skilled in the art to understand, the present invention will be further described below in conjunction with the accompanying drawings.

[0017] Figure 1 It is a flowchart of the steps of a door anti-collision method based on shape memory alloy of the present invention. Detailed implementation manners

[0018] To better understand the present invention, more detailed descriptions of various aspects of the present invention will be made with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present invention and do not limit the scope of the present invention in any way. Throughout the specification, the expression "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, terms such as "substantially", "about" and similar terms are used as terms indicating approximation and not as terms indicating degree, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by those of ordinary skill in the art. Additionally, in the present invention, the order of description of each step process does not necessarily represent the order in which these processes occur in actual operation, unless there are clear other limitations or can be deduced from the context.

[0019] It should also be understood that expressions such as "including", "including having", "having", "containing" and / or "containing having" in this specification are open-ended rather than closed-ended expressions, which mean the presence of the stated features, elements and / or components, but do not exclude the presence of one or more other features, elements, components and / or their combinations. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of features rather than just individual elements in the list. In addition, when describing embodiments of the present invention, the use of "may" means "one or more embodiments of the present invention". And, the term "exemplary" is intended to refer to an example or illustration.

[0020] Unless otherwise defined, all terms used herein (including engineering terms and scientific and technical terms) have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. It should also be understood that unless there is a clear statement in the present invention, words defined in common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense.

[0021] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] Embodiment 1: Please refer to Figure 1, a method for preventing door collisions based on shape memory alloy, comprising: S1: Capture piezoelectric signals, trigger a multi-physical field coupling monitoring process through the piezoelectric signals, and output collision events and collision types; S2: Activate the low phase change temperature region based on the collision event and the collision type and obtain the target volume fraction, dynamically adjust the deformation parameters to generate door deformation; S3: Obtain the energy absorbed by deformation, obtain the active recovery amount based on the energy absorbed by deformation, and actively recover the door deformation, where the active recovery amount includes the conventional recovery amount and the superelastic assisted recovery amount.

[0023] In this embodiment, capturing piezoelectric signals, triggering a multi-physical field coupling monitoring process through the piezoelectric signals, and outputting collision events and collision types can be specifically implemented through the following steps: S101: Capture the piezoelectric signals through a distributed piezoelectric sensing network and convert them into output voltage. When the output voltage exceeds a set threshold (for example, 10 mV), the system determines that a collision may occur and triggers the multi-physical field coupling monitoring process; S102: Obtain the cross-sectional area of the pressure fiber, and convert the output voltage into a pressure value based on the cross-sectional area of the pressure fiber. The mathematical description is , where F is the pressure value (unit: N / m 2 ), d 33 is the piezoelectric constant (unit: C / N), A is the cross-sectional area of the pressure fiber (unit: m 2 ), G is the amplifier gain coefficient (unit: V / C), and V is the output voltage (V); S103: Obtain the temperature rise and resistance change at the collision point during the collision process, and output coupling monitoring parameters through a data fusion algorithm based on the pressure value. The mathematical description is , where S(t) is the coupling monitoring parameter, ω1, ω2, and ω3 are weights, and the default values are 0.5, 0.3, and 0.2 respectively. F max is the ultimate compressive strength of the material, △R is the resistance change, △T is the temperature rise, △R max is the resistance change corresponding to the maximum allowable tensile amount of the wire, and △T max is the maximum temperature rise allowed by the system; S104: Output the collision event based on the coupling monitoring parameter. The collision event includes an effective collision event and an invalid collision event. A coupling monitoring parameter threshold is preset. When the coupling monitoring parameter is greater than or equal to the coupling monitoring parameter threshold, it is determined as the effective collision event, otherwise it is determined as the invalid collision event; Example: At the moment of collision, 5 piezoelectric fiber nodes around the collision point are under pressure, and the average output voltage is 41.5 mV, d 33= 650 pC / N, G = 100 V / pC, A = 7.85×10 -5 m 2 Then the converted pressure value is F = 0.0415 / (650×10 -12 ×100×10 12 ×7.85×10 -5 ) = 8.133 N / m 2 At this time, the temperature rise and resistance change at the collision point are 1 Ω and 3 °C respectively. The resistance changes corresponding to the ultimate compressive strength of the material, the maximum allowable tensile amount of the wire, and the maximum temperature rise allowed by the system are 50 N / m 2 、5 Ω and 20 °C respectively. Then the coupling monitoring parameter S(t) = 0.5×(8.133 / 50) + 0.3×(1 / 5) + 0.2×(3 / 20) = 0.17 can be obtained, which exceeds the threshold range, and it is determined that this collision is an effective collision event.

[0024] S105: Establish a collision feature database based on the output voltage and pulse width, and use a convolutional neural network to classify the collision types. Example: When the vehicle hits a 150 - mm - diameter column at 40 km / h: The output voltage at the impact point is 12 V, the pulse width is 3 ms, the output voltage 5 cm behind the impact point is 8 V, and the pulse width is 5 ms. The system identifies it as a medium - speed collision with a concentrated load.

[0025] In this embodiment, based on the collision event and the collision type, the low - phase - change - temperature region is activated and the target volume fraction is obtained, and the deformation parameters are dynamically adjusted to generate a deformation of the car door. Specifically, it can be implemented through the following steps: S201: When the effective collision event is output, the collision point is electrified and the electrified temperature is obtained. The mathematical description of the electrified temperature is , where T0 is the temperature before electrification, V T is the electrified voltage, R is the real - time resistance, ρ is the material density, c is the specific heat capacity, α is the thermal diffusivity, is the geometric factor, (x, y) is the coordinate of the electrified point, and (x0, y0) is the coordinate of the collision point; S202: When the electrified temperature does not reach the preset phase - change temperature, the electrified voltage is increased. If it is still insufficient, the adjacent area is activated for auxiliary heating; when the electrified temperature reaches the phase - change temperature, the low - phase - change - temperature region is activated. Example: The collision point is electrified with 12 V, so that the electrified temperature is about 35.6 °C, which does not reach the phase - change temperature (40 °C), then the voltage is increased to 24 V, so that the electrified temperature reaches the phase - change temperature and the low - phase - change - temperature region is activated; S203: Set the target volume fraction according to the collision type (for example, set it to 0.1 for low-speed rubbing (5 km / h), 0.3 for medium-speed side collision (40 km / h), and 0.5 for high-speed impact (80 km / h)), dynamically adjust the deformation parameters according to the phase change kinetics equation, and the mathematical description of the phase change kinetics equation is , where is the volume fraction, A0 is the kinetic coefficient, is the actual stress, is the critical stress, S is the saturation stress, Q is the activation energy, U is the gas constant. When the volume fraction obtained according to the energized temperature does not match the target volume fraction, adjust the heating power and apply a pre-tightening force (increase ) etc. to make the volume fraction consistent with the target volume fraction, so that the door deforms and offsets the negative impact of the collision.

[0026] In this embodiment, obtain the deformation absorption energy, obtain the active recovery amount based on the deformation absorption energy, and actively recover the door deformation. The active recovery amount includes the conventional recovery amount and the superelastic auxiliary recovery amount, and can be specifically implemented through the following steps: S301: Obtain the original length of the door anti-collision beam and heat the collision point to obtain the recovery temperature (that is, the temperature difference generated by heating the collision point), and obtain the conventional recovery amount based on the original length of the door anti-collision beam and the recovery temperature. The mathematical description is , where is the conventional recovery amount, is the thermal expansion coefficient, is the recovery temperature, and L0 is the original length of the door anti-collision beam; S302: Apply a mechanical pre-tightening force, and obtain the superelastic auxiliary recovery amount based on the deformation absorption energy and the mechanical pre-tightening force. The mathematical description is , where is the superelastic auxiliary recovery amount, is the superelastic recovery factor, and the default value is taken as 0.15, is the mechanical pre-tightening force, and E is the deformation absorption energy; S303: Obtain the active recovery amount based on the sum of the conventional recovery amount and the superelastic auxiliary recovery amount, and actively recover the door deformation amount generated during the collision process and the offset collision process.

[0027] Embodiment 2: A door anti-collision system based on shape memory alloy, including a coupling monitoring module, a door deformation module, and a deformation recovery module; The coupling monitoring module is used to capture piezoelectric signals, trigger the multi-physical field coupling monitoring process through the piezoelectric signals, and output collision events and collision types. Specifically: capture the piezoelectric signals through a distributed piezoelectric sensing network and convert them into output voltages. When the output voltage exceeds a set threshold, the system determines that a collision may occur and triggers the multi-physical field coupling monitoring process; obtain the cross-sectional area of the pressure fiber, and convert the output voltage into a pressure value based on the cross-sectional area of the pressure fiber; obtain the temperature rise and resistance change at the collision point during the collision process, and output coupling monitoring parameters through a data fusion algorithm based on the pressure value; output the collision events based on the coupling monitoring parameters. The collision events include valid collision events and invalid collision events. A preset coupling monitoring parameter threshold is set. When the coupling monitoring parameters are greater than or equal to the coupling monitoring parameter threshold, it is determined as the valid collision event, otherwise it is determined as the invalid collision event; establish a collision feature database based on the output voltage and pulse width, and classify the collision types using a convolutional neural network.

[0028] The door deformation module is used to activate the low phase change temperature region and obtain the target volume fraction based on the collision event and the collision type, and dynamically adjust the deformation parameters to generate door deformation. Specifically: when the valid collision event is output, the collision point is energized to obtain the energized temperature; when the energized temperature does not reach the preset phase change temperature, the energized voltage is increased. If it is still insufficient, the adjacent area is activated for auxiliary heating; when the energized temperature reaches the phase change temperature, the low phase change temperature region is activated; set the target volume fraction according to the collision type, and dynamically adjust the deformation parameters according to the phase change kinetic equation. When the volume fraction obtained according to the energized temperature does not match the target volume fraction, the heating power, pre-tightening force, etc. are adjusted through a PID controller to make the volume fraction consistent with the target volume fraction, causing the door to deform and offset the negative impact of the collision.

[0029] The deformation recovery module is used to obtain the deformation absorption energy, obtain the active recovery amount based on the deformation absorption energy, and actively recover the door deformation. The active recovery amount includes the conventional recovery amount and the superelastic auxiliary recovery amount. Specifically: obtain the original length of the door anti-collision beam and heat the collision point to obtain the recovery temperature, and obtain the conventional recovery amount based on the original length of the door anti-collision beam and the recovery temperature; apply a mechanical pre-tightening force, and obtain the superelastic auxiliary recovery amount based on the deformation absorption energy and the mechanical pre-tightening force; obtain the active recovery amount based on the sum of the conventional recovery amount and the superelastic auxiliary recovery amount, so that the door deformation generated during the collision process and the collision offset process is actively recovered.

[0030] The above are only the preferred embodiments of the present invention and do not impose any formal restrictions on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A door anti-collision method based on shape memory alloy, characterized in that, The implementation of the door anti-collision method includes the following steps: S1: Capture piezoelectric signals, trigger a multi-physical field coupling monitoring process through the piezoelectric signals, and output collision events and collision types; S2: Activate the low phase transition temperature region based on the collision event and the collision type and obtain the target volume fraction, and dynamically adjust the deformation parameters to generate door deformation; S3: Obtain the energy absorbed by deformation, obtain the active recovery amount based on the energy absorbed by deformation, and actively recover the door deformation. The active recovery amount includes a conventional recovery amount and a super-elastic assisted recovery amount.

2. The door anti-collision method according to claim 1, wherein The specific steps of step S1 include: S101: Capture the piezoelectric signals and convert them into output voltages. When the output voltage exceeds the set threshold, trigger the multi-physical field coupling monitoring process; S102: Obtain the cross-sectional area of the pressure fiber, and convert the output voltage into a pressure value based on the cross-sectional area of the pressure fiber; S103: Obtain the temperature rise amount and resistance change at the collision point, and output the coupling monitoring parameters through a data fusion algorithm based on the pressure value; S104: Output the collision event based on the coupling monitoring parameters. The collision event includes an effective collision event and an ineffective collision event. Preset the coupling monitoring parameter threshold. When the coupling monitoring parameter is greater than or equal to the coupling monitoring parameter threshold, it is determined as the effective collision event, otherwise it is determined as the ineffective collision event; S105: Establish a collision feature database based on the output voltage and pulse width, and classify the collision type using a convolutional neural network.

3. The door anti-collision method according to claim 2, wherein The mathematical description of the pressure value is , where F is the pressure value, d 33 is the piezoelectric constant, A is the cross-sectional area of the pressure fiber, G is the amplifier gain coefficient, and V is the output voltage.

4. The door anti-collision method according to claim 3, characterized in that, The mathematical description of the coupling detection parameter is , where S(t) is the coupling monitoring parameter, ω1, ω2, and ω3 are weights, and F max is the ultimate compressive strength of the material, △R is the resistance change, △T is the temperature rise, and △R max is the resistance change corresponding to the maximum allowable tensile amount of the wire, and △T max is the maximum temperature rise allowed by the system.

5. The door anti-collision method according to claim 4, characterized in that, The specific steps of step S2 include: S201: When the effective collision event is output, energize the collision point and obtain the energized temperature; S202: When the energized temperature does not reach the preset phase transition temperature, increase the energizing voltage. If it is still insufficient, activate the adjacent area for auxiliary heating; when the energized temperature reaches the phase transition temperature, activate the low phase transition temperature region; S203: Set the target volume fraction according to the collision type, and dynamically adjust the deformation parameters according to the phase transition kinetics equation.

6. The door anti-collision method according to claim 5, characterized in that The mathematical description of the energized temperature is , where T0 is the temperature before energization, V T is the energized voltage, R is the real-time resistance, ρ is the material density, c is the specific heat capacity, α is the thermal diffusivity, is the geometric factor, (x, y) is the coordinate of the energized point, and (x0, y0) is the coordinate of the collision point.

7. The door anti-collision method according to claim 6, wherein The mathematical description of the phase change kinetic equation is , where is the volume fraction, A0 is the kinetic coefficient, is the actual stress, is the critical stress, S is the saturation stress, Q is the activation energy, and U is the gas constant.

8. The door anti-collision method according to claim 1, characterized in that The specific acquisition of the conventional recovery amount in step S3 includes: Obtain the original length of the door anti-collision beam and heat the collision point to obtain the recovery temperature. Based on the original length of the door anti-collision beam and the recovery temperature, obtain the conventional recovery amount, and the mathematical description is , where is the conventional recovery amount, is the coefficient of thermal expansion, is the recovery temperature, and L0 is the original length of the door anti-collision beam.

9. The door anti-collision method according to claim 8, characterized in that, The specific acquisition of the super-elastic assisted recovery amount in step S3 includes: Apply a mechanical pre-tightening force, and obtain the hyperelastic assisted recovery amount based on the deformation energy absorption and the mechanical pre-tightening force. The mathematical description is , where is the hyperelastic assisted recovery amount, is the hyperelastic recovery factor, is the mechanical pre-tightening force, and E is the deformation energy absorption.

10. A door anti-collision system based on shape memory alloy, characterized in that, The system is applied to the door anti-collision method as described in any one of claims 1-9, and includes a coupling monitoring module, a door deformation module, and a deformation recovery module; The coupling monitoring module is used to capture piezoelectric signals, trigger a multi-physical field coupling monitoring process through the piezoelectric signals, and output collision events and collision types; The door deformation module is used to activate the low phase transition temperature region based on the collision event and the collision type and obtain the target volume fraction, and dynamically adjust the deformation parameters to generate door deformation; The deformation recovery module is used to obtain the energy absorbed by deformation, obtain the active recovery amount based on the energy absorbed by deformation, and actively recover the door deformation. The active recovery amount includes a conventional recovery amount and a super-elastic assisted recovery amount.

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