Variable stiffness control method for a crash cushion and a crash protection system

Abstract

The application discloses a variable rigidity control method and a protection system of a crash pad, wherein the inside of the crash pad comprises fixed energy-absorbing units and adjustable energy-absorbing units; the adjustable energy-absorbing units are structural members with anisotropic stress characteristics and can be switched between a first rigidity mode and a second rigidity mode through rotation. When a rear target vehicle meets a collision risk condition, a corresponding collision action area is determined, and the adjustable energy-absorbing units are laterally differentiated and configured based on the distribution of the collision action area in the width direction; meanwhile, different rows of adjustable energy-absorbing units are longitudinally classified and configured based on collision intensity, and position limiting or mechanical locking is performed after entering a preset collision time window. The application can form an asymmetric rigidity distribution under a bias collision working condition and a symmetric rigidity distribution under a non-bias collision working condition, thereby improving energy-absorbing utilization efficiency, reducing eccentric moment and improving overall protection stability.

Description

Technical Field

[0001] This invention relates to the field of road safety protection technology, and in particular to a method and system for adjusting the protective structure of a crash vehicle, specifically a control method and system for adjusting the energy-absorbing structure at the rear of a crash vehicle based on the vehicle's operating status and external target information. Background Technology

[0002] In routine maintenance and construction work on highways and urban expressways, crash buffer vehicles serve as a physical barrier protecting construction workers ahead and vehicles rear-ending them. They are typically parked behind the construction area to provide isolation and protection. The crash buffer device mounted at the rear of the crash buffer vehicle is designed to absorb the collision energy of a rear-end collision through the crushing deformation of its internal structure. With the development of traffic safety technology, modern crash buffer vehicles have gradually been equipped with collision warning systems and protective adjustment mechanisms. However, facing increasingly complex actual traffic conditions, existing technologies still have certain limitations.

[0003] Existing crash buffers typically employ a fixed stiffness design for their internal energy-absorbing materials. However, real-world rear-end collisions are complex and varied, ranging from 100% full-overlap head-on collisions to partially-overlap offset collisions. For fixed energy-absorbing structures, a low stiffness design can lead to excessive vehicle intrusion in offset collisions due to the reduced force-bearing area; conversely, a high stiffness design can generate excessive collision acceleration in head-on collisions, causing secondary injuries to occupants. While some existing technologies propose adjusting the overall height or lateral position of the crash buffer to address different collision types, these solutions do not address the issue of a single internal stiffness distribution, failing to dynamically and precisely adapt the energy-absorbing characteristics to the actual collision scenario.

[0004] Therefore, how to improve the protective effect of anti-collision vehicles in a stationary operating state, and enable their anti-collision buffer devices to adapt to complex and ever-changing collision conditions, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a variable stiffness control method and protection system for anti-collision pads, so as to solve the problem that existing anti-collision buffer devices mainly adopt fixed symmetrical energy-absorbing structures and are difficult to dynamically adjust for different collision conditions.

[0006] Another objective of this invention is to provide an array-type anti-collision buffer device that takes into account both basic buffering capacity and dynamic adjustment capability. By combining fixed energy-absorbing units and adjustable energy-absorbing units inside the anti-collision pad, the device has basic protective performance under various working conditions, and can be specifically configured with the stiffness mode of the adjustable energy-absorbing units according to the collision risk, collision area and collision intensity of the target vehicle before a collision occurs.

[0007] A method for controlling the variable stiffness of a collision buffer device, wherein the collision buffer device has multiple energy-absorbing units arranged inside, wherein at least some of the energy-absorbing units are adjustable energy-absorbing units, and the rest are fixed energy-absorbing units; The adjustable energy-absorbing unit is a structural component with anisotropic force characteristics and is configured to be controllably rotated to switch between a first stiffness mode and a second stiffness mode. The first stiffness mode has a greater compressive stiffness along the collision direction than the second stiffness mode. The fixed energy-absorbing unit is fixedly installed to provide basic buffering capacity. The control method includes: S0. When a target vehicle behind is detected to meet the preset collision risk conditions, stiffness adjustment is triggered. S1. Determine the collision action area of ​​the target vehicle acting on the anti-collision buffer device under the predicted collision conditions based on the target vehicle's operating status information; S2. Based on the distribution of the collision area in the width direction, the adjustable energy absorption unit is configured with lateral differential stiffness, so that the adjustable energy absorption unit located in the collision area switches to the first stiffness mode, and the adjustable energy absorption unit located outside the collision area maintains the second stiffness mode. S3. Based on the collision intensity characterization parameters of the target vehicle, the adjustable energy absorption units are configured longitudinally in stages, so that at least some of the adjustable energy absorption units near the frontal impact surface are switched to the first stiffness mode. S4. After the target vehicle enters the preset collision time window, the adjustable energy absorption unit that has completed the mode switching is positioned or mechanically locked.

[0008] As one specific embodiment, the preset collision risk condition is determined in the following way: Obtain the offset relationship between the longitudinal axis of the vehicle body center and the single-sided edge of the road when the anti-collision buffer device is stationary; Based on the aforementioned bias relationship and the width range of the anti-collision buffer device, the target monitoring area is determined in the sensing coordinate system; The system tracks the trajectory of a target vehicle behind it and determines the area of ​​impact when the target vehicle enters the target monitoring area.

[0009] As one specific embodiment, after triggering the determination of the collision area of ​​the target vehicle, the determination process includes: Obtain the relative speed and direction of motion information of the target vehicle; In a two-dimensional projection plane established with the rear of the anti-collision buffer device as a reference, the position of the target vehicle within a preset time window is extrapolated according to the relative speed and direction of motion to obtain the predicted profile of the target vehicle. The collision action area is determined based on the overlap position and overlap range between the predicted contour and the anti-collision buffer device in the width direction.

[0010] As one specific embodiment, hierarchical timing control is performed based on the remaining collision time of the target vehicle, which includes: A first time threshold and a second time threshold are set, wherein the first time threshold is greater than the second time threshold; When the remaining time of the collision is less than or equal to the first time threshold and greater than the second time threshold, the energy absorption unit is controlled to perform stiffness mode switching to complete the lateral differential stiffness configuration and the longitudinal graded stiffness configuration. When the remaining time of the collision is less than or equal to the second time threshold, the stiffness mode switching process of the energy absorption unit is stopped, and the energy absorption unit is subjected to position limiting or mechanical locking to maintain the current stiffness mode. Specifically, when the remaining collision time of the target vehicle is less than or equal to the second time threshold when it is first identified, the position limit or mechanical locking is executed directly without performing the stiffness mode switching.

[0011] As one specific embodiment, the lateral differential stiffness configuration and longitudinal hierarchical configuration are collaboratively determined based on the overlap of the predicted collision velocity range and the collision action area, including: Predict the collision speed based on the speed, distance, and deceleration of vehicles behind; When the predicted collision velocity is in the first velocity range, each adjustable energy absorption unit maintains the second stiffness mode. When the predicted collision velocity is in the second velocity range and the predicted collision action area is offset overlap, the adjustable energy absorption units located on the collision side switch to the first stiffness mode, while the adjustable energy absorption units located on the non-collision side maintain the second stiffness mode. When the predicted collision velocity is in the second velocity range and the predicted collision action area is non-biased overlap, each adjustable energy absorption unit adopts a symmetrical stiffness mode configuration along the width direction. When the predicted collision velocity is in the third velocity range, at least some of the adjustable energy-absorbing units near the impact surface switch to the first stiffness mode.

[0012] A variable stiffness protection system for a crash vehicle includes an array of crash buffers installed at the rear of the vehicle. The array-type anti-collision buffer device includes an outer shell and multiple energy-absorbing units disposed within the outer shell, wherein the energy-absorbing units are arranged in a multi-row, multi-column array. The energy absorption unit includes a fixed energy absorption unit and an adjustable energy absorption unit. The fixed energy absorption unit is fixedly installed inside the outer housing to provide basic buffering capacity. The adjustable energy-absorbing unit is an energy-absorbing component with anisotropic force characteristics. Each adjustable energy-absorbing unit is installed in the outer housing through a rotating connection structure and connected to the drive assembly to rotate and switch between two target angle positions, thereby changing the relative relationship between its main force direction and the collision direction. The outer housing is provided with a limiting or locking structure corresponding to the target angle position, which is used to maintain the angle state of the adjustable energy-absorbing unit after it is switched to the target angle.

[0013] As one specific embodiment, the adjustable energy absorption unit includes an energy absorption core with a directional internal structure and a covering shell, wherein the energy absorption core is any one or a combination of a honeycomb structure, a layered composite structure, a corrugated folded structure or a grid structure.

[0014] As one specific embodiment, the adjustable energy absorption unit is divided into several control groups in rows or columns. Multiple adjustable energy absorption units in each control group are connected to the same drive component through a linkage transmission structure to realize the synchronous angle switching of the energy absorption units in the control group. A flexible connector is provided between the drive component and the adjustable energy absorption unit to buffer the impact load and compensate for transmission errors when the energy absorption unit rotates to the target angle.

[0015] As one specific embodiment, the adjustable energy-absorbing unit is arranged in a gapped array inside the outer housing, and adjacent rows of energy-absorbing units are staggered in the width direction to reduce mechanical interference between adjacent energy-absorbing units during rotation switching.

[0016] The advantages and beneficial effects of this invention are as follows: Compared to existing anti-collision structures employing an overall symmetrical stiffness configuration, this invention utilizes a collaborative control strategy based on the predicted collision velocity range and the distribution of the collision impact area. This results in an asymmetrical stiffness distribution in the width direction of the anti-collision buffer device, composed of a combination of a first stiffness mode and a second stiffness mode, and a graded stiffness configuration in the thickness direction. Under offset collision conditions, this asymmetrical stiffness configuration provides the impact side with higher local intrusion resistance while maintaining a relatively compliant stress state on the non-impact side. This allows the stress response of the anti-collision buffer device to better match the actual collision load distribution, reducing the eccentric moment caused by unilateral stress and minimizing the tendency for lateral deflection of the structure. Furthermore, by creating a gradient stiffness distribution between different rows, the stress process in the initial and later stages of the collision is smoother, reducing the transient impact peak and improving the utilization efficiency of the energy-absorbing structure within the actual load-bearing area, thereby enhancing overall protective stability. Attached Figure Description

[0017] Figure 1 This is the control logic diagram of the present invention.

[0018] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0020] Existing crash buffer devices mostly employ integral or symmetrical structural designs, resulting in relatively uniform mechanical properties across their width. These are primarily optimized for head-on, center-collision scenarios. However, in real-world road conditions, crash-resistant vehicles are typically parked along one edge of the road, resulting in an offset relative to the lane. Consequently, vehicles approaching from behind are more likely to intrude along the open lane side if they lose control or fail to avoid a collision in time, leading to asymmetrical collisions. The distribution of collision loads across the width of the crash buffer device often exhibits significant unevenness. If a uniform or symmetrical energy-absorbing structure is still used, the energy absorption capacity of the impact-side area may be insufficient, while the non-impact-side structure may not be effectively utilized. This results in a mismatch between the overall energy absorption effect of the protective structure and the actual collision load distribution, affecting the effectiveness of the protection.

[0021] Based on this, the present invention proposes a variable stiffness control method for a collision buffer device, wherein the collision buffer device has multiple energy-absorbing units arranged inside, wherein at least some of the energy-absorbing units are adjustable energy-absorbing units, and the rest are fixed energy-absorbing units. The adjustable energy-absorbing unit is a structural component with anisotropic force characteristics and is configured to be controllably rotated to switch between a first stiffness mode and a second stiffness mode. The first stiffness mode has a greater compressive stiffness along the collision direction than the second stiffness mode. The fixed energy-absorbing unit is fixedly installed to provide basic buffering capacity. The control method includes: S0. When a target vehicle behind is detected to meet the preset collision risk conditions, stiffness adjustment is triggered. S1. Determine the collision area of ​​the target vehicle acting on the anti-collision buffer device under predicted collision conditions based on the target vehicle's operating status information. In this invention, the collision area characterizes the spatial range within which the target vehicle may come into contact with the anti-collision buffer device under predicted collision conditions. The collision area can be determined based on information such as the target vehicle's relative speed, driving direction, lateral position, and outline dimensions, or it can be obtained by extrapolating the target vehicle's trajectory within a preset time window. Those skilled in the art can use various methods to determine this area, and are not limited to a specific calculation model.

[0022] S2. Based on the distribution of the collision area in the width direction, the adjustable energy-absorbing unit is configured with lateral differential stiffness, so that the adjustable energy-absorbing unit located within the collision area switches to the first stiffness mode, and the adjustable energy-absorbing unit located outside the collision area maintains the second stiffness mode; by dividing the energy-absorbing unit into two parts, one inside and one outside the collision area, and configuring them with different stiffness modes respectively, the stiffness distribution of the anti-collision buffer device in the width direction matches the collision area, thereby improving the utilization efficiency of energy-absorbing resources in the actual load area.

[0023] S3. Based on the collision intensity characterization parameters of the target vehicle, the adjustable energy-absorbing units in different rows are configured longitudinally in a graded manner, so that at least some of the adjustable energy-absorbing units near the impact surface are switched to the first stiffness mode. In this invention, the collision intensity characterization parameters are used to reflect the degree of impact that the target vehicle may generate on the anti-collision buffer device. These parameters can be the predicted collision speed, mass information of the target vehicle, or a combination of both, or equivalent indices derived from the above parameters. This invention does not limit the specific calculation form. By configuring the stiffness of different rows of energy-absorbing units in a graded manner in the thickness direction of the anti-collision buffer device, the structure has higher initial resistance under high impact conditions, while maintaining a certain buffering performance under low impact conditions, so as to take into account different collision conditions.

[0024] S4. After the target vehicle enters the preset collision time window, the adjustable energy-absorbing unit that has completed the mode switching is positioned or mechanically locked. The locking can be achieved through a mechanical limiting structure, a snap-fit ​​structure or other equivalent means. The purpose is to prevent the energy-absorbing unit from rotating unexpectedly under the impact when a collision occurs, thereby ensuring the stability of the preset stiffness distribution.

[0025] Compared to existing anti-collision structures employing an overall symmetrical stiffness configuration, this invention utilizes a collaborative control strategy based on the predicted collision velocity range and the distribution of the collision impact area. This results in an asymmetrical stiffness distribution in the width direction of the anti-collision buffer device, composed of a combination of a first stiffness mode and a second stiffness mode, and a graded stiffness configuration in the thickness direction. Under offset collision conditions, this asymmetrical stiffness configuration provides the impact side with higher local intrusion resistance while maintaining a relatively compliant stress state on the non-impact side. This allows the stress response of the anti-collision buffer device to better match the actual collision load distribution, reducing the eccentric moment caused by unilateral stress and minimizing the tendency for lateral deflection of the structure. Furthermore, by creating a gradient stiffness distribution between different rows, the stress process in the initial and later stages of the collision is smoother, reducing the transient impact peak and improving the utilization efficiency of the energy-absorbing structure within the actual load-bearing area, thereby enhancing overall protective stability.

[0026] Furthermore, the preset collision risk conditions are determined in the following way: Obtain the offset relationship between the longitudinal axis of the vehicle body center and the single-sided edge of the road when the anti-collision buffer device is stationary; Based on the aforementioned bias relationship and the width range of the anti-collision buffer device, the target monitoring area is determined in the sensing coordinate system; The system tracks the trajectory of a target vehicle behind it and determines the area of ​​impact when the target vehicle enters the target monitoring area.

[0027] In this embodiment, the preset collision risk condition is not determined solely based on the presence of a target vehicle behind, but rather by considering the offset relationship of the anti-collision buffer device relative to the road edge when stationary. Specifically, since the anti-collision buffer device is typically parked close to one side of the road, the passable space on both sides differs. The offset relationship between the vehicle's central longitudinal axis and one side edge of the road is first obtained. Based on this offset relationship and the width range of the anti-collision buffer device, the target monitoring area is determined in the perception coordinate system. Subsequently, the trajectory of the target vehicle behind is tracked. Only when the target vehicle enters the target monitoring area does the system trigger further determination of its collision area, thus ensuring that subsequent control primarily targets with actual collision risk.

[0028] The process of determining the collision zone of the target vehicle after it is triggered includes: Obtain the relative speed and direction of motion information of the target vehicle; In a two-dimensional projection plane established with the rear of the anti-collision buffer device as a reference, the position of the target vehicle within a preset time window is extrapolated according to the relative speed and direction of motion to obtain the predicted profile of the target vehicle. The collision zone is determined based on the overlap position and overlap range between the predicted profile and the collision avoidance buffer device in the width direction. In this embodiment, the predicted profile of the target vehicle can be obtained by extrapolating its current position, relative speed, and direction of motion. The extrapolation time can be a preset time window or a time range determined based on collision risk. This invention does not limit the specific extrapolation model.

[0029] In this embodiment of the invention, electromechanical response delays inevitably exist when the energy-absorbing units inside the anti-collision buffer device switch between different stiffness modes. For example, when the energy-absorbing unit is rotated to the target angle by a drive motor to achieve stiffness mode switching, a certain physical execution time is usually required. If the control system only adjusts the stiffness based on the collision space distribution results without combining the collision proximity for timing control, some energy-absorbing units may still be in the process of mode switching when the collision occurs and have not yet stabilized to the target stiffness state, thereby affecting the effective establishment of the preset stiffness distribution at the moment of actual collision and reducing the overall protection reliability. Based on this, this embodiment introduces a hierarchical timing control mechanism based on the time remaining before collision (TTC). Specifically, a first time threshold and a second time threshold can be preset, wherein the first time threshold is greater than the second time threshold. When the TTC of the target vehicle is between the first time threshold and the second time threshold, the system determines that there is still an effective time window for performing stiffness mode adjustment, and at this time, it triggers each energy-absorbing unit to switch modes according to the predetermined lateral differential configuration and longitudinal hierarchical configuration. When the target vehicle's TTC further decreases to less than or equal to the second time threshold, the system determines that it has entered the near-collision stage. At this time, it no longer continues to perform stiffness mode switching, but immediately performs position limiting or mechanical locking on the energy absorption unit in the current state to avoid the energy absorption unit being in a transitional state that has not completed switching at the moment of collision.

[0030] Furthermore, in some extreme cases, the target vehicle's Time To Catch (TTC) may already be less than or equal to the second time threshold when it is first identified, indicating that the system does not have sufficient physical execution time to complete the stiffness mode adjustment. In this embodiment, instead of forcibly switching modes, the current stiffness distribution of the collision avoidance buffer device is directly locked, allowing it to meet the impending collision in its current stable state. This ensures that the determinism of the structural state and protective stability can be maintained even under extremely short response time conditions.

[0031] In this embodiment of the invention, although the anti-collision buffer device preferably performs lateral differential stiffness configuration and longitudinal graded stiffness configuration according to the collision area of ​​the target vehicle, the above-mentioned optimized control is based on the premise that the target recognition result has sufficient reliability. Under conditions such as direct sunlight, nighttime glare, backlight reflection, and rain / fog obstruction, the visual perception result may experience a decrease in stability, thereby affecting the accuracy of determining the target's position, outline, or motion state. If fine-grained stiffness adjustment based on the local collision area is continued under such conditions, it may lead to inconsistency between the stiffness configuration and the actual collision area, thus weakening the protective effect.

[0032] Based on this, in this embodiment, a perception failure fallback control mechanism is further set up. When the visual perception quality information indicates that the current recognition result does not meet the preset reliability condition, while other perception units still detect a target vehicle behind that meets the collision risk condition, the system stops the differential stiffness configuration logic based on the collision action area, and instead controls all the energy absorption units to switch to the first stiffness mode, and performs position limit or mechanical locking after the switching is completed. In this way, in the case where the collision area cannot be reliably determined, a global high-stiffness defense state can be used to cope with potential collisions, thereby improving the protection certainty and safety redundancy of the system in complex environments.

[0033] In this embodiment, the stiffness configuration of the anti-collision buffer device is jointly controlled based on the predicted collision speed range of the target vehicle and the spatial distribution of the collision action area.

[0034] Specifically, when the predicted collision speed is within the first speed range, each adjustable energy absorption unit as a whole maintains the second stiffness mode to provide basic buffering capacity; when the predicted collision speed is within the second speed range and the collision action area is distributed in a biased manner, some of the adjustable energy absorption units on the collision side switch to the first stiffness mode, while the adjustable energy absorption units on the non-collision side maintain the second stiffness mode, so as to form enhanced supporting capacity on the collision side; when the predicted collision speed is within the third speed range, at least some rows of adjustable energy absorption units close to the impact surface switch to the first stiffness mode to form higher local anti-intrusion capacity at the initial stage of the collision.

[0035] Specifically, a fixed time threshold T2 is set, and the T2 is equal to the total execution time required for the energy absorption unit to complete the stiffness mode switching and position locking fixation, and the value range of the T2 is 0.3 s to 0.8 s; According to the real-time speed, real-time deceleration of the rear vehicle and the real-time distance from the anti-collision vehicle, the dynamic time threshold T1 is dynamically calculated and updated. The T1 represents the critical time for judging whether a collision is inevitable: if the remaining collision time TTC ≤ T1, it is determined that the rear vehicle cannot avoid the collision through effective braking and the stiffness adjustment needs to be started; but the T1 is always greater than T2; When the remaining collision time TTC satisfies T2 < TTC ≤ T1, control the energy absorption unit to perform stiffness mode switching to complete the lateral differential stiffness configuration and longitudinal hierarchical stiffness configuration; When the remaining collision time TTC ≤ T2, stop the stiffness mode switching process of the energy absorption unit, and perform position limit or mechanical locking on the energy absorption unit through a solenoid valve, a locking pin or a self-locking mechanism to make it maintain the current stiffness mode; Specifically, if the remaining collision time TTC is less than or equal to T2 when the target vehicle is initially identified, the position limit or mechanical locking is executed directly without switching the stiffness mode. In some implementations, when the collision area is fully overlapping, each row of adjustable energy-absorbing units is configured with a symmetrical stiffness mode along the width direction to ensure overall force balance.

[0036] In this embodiment, the stiffness configuration control can be abstracted as a two-dimensional decision model based on the predicted collision velocity and the distribution of the collision area. For example... Figure 1 As shown, the system uses the predicted collision speed range as the longitudinal dimension and the distribution of the collision area in the width direction as the lateral dimension to determine the stiffness mode configuration strategy of the adjustable energy-absorbing unit based on different combinations of conditions. First, the collision speed is predicted based on the speed, distance, and deceleration of the vehicle behind. Specifically, when the predicted collision speed is low, each adjustable energy-absorbing unit maintains the second stiffness mode as a whole. When the predicted collision speed is in the medium range, if the predicted collision area is offset, a laterally asymmetrical stiffness configuration is adopted, switching the collision side to the first stiffness mode and the non-collision side to the second stiffness mode. If the collision area is non-offset, a symmetrical configuration is adopted. When the predicted collision speed further increases, more rows of adjustable energy-absorbing units near the impact surface are switched to the first stiffness mode, forming a longitudinally graded stiffness distribution. When the collision area is non-offset in the width direction, it indicates that the collision load is relatively uniform in the width direction of the anti-collision buffer device. At this time, the system no longer implements the lateral differential stiffness configuration, but adopts a symmetrical stiffness mode distribution to avoid additional moments caused by artificially introduced asymmetrical stiffness, thereby ensuring the stability of the structure under stress.

[0037] like Figure 1 As shown, the aforementioned two-dimensional decision model enables adaptive stiffness configuration under different collision conditions. This control decision model couples two key factors: predicted collision velocity and lateral collision distribution. This transforms the stiffness configuration of the crash barrier from a fixed strategy to a condition-driven strategy, allowing the stiffness distribution to dynamically match the actual collision load characteristics. Compared to traditional methods that adjust based on only a single parameter, this model can automatically switch between symmetrical and asymmetrical configurations between offset and non-offset collisions, and combines collision intensity to achieve longitudinal hierarchical control, thereby improving the completeness and adaptability of the control strategy.

[0038] Through the aforementioned asymmetric stiffness configuration, under offset collision conditions, the collision side and the non-collision side exhibit different force responses. The collision side primarily bears the collision reaction force, while the non-collision side maintains a low level of participation, thereby reducing the overall structural force eccentricity and minimizing the moment effect caused by unilateral force. Simultaneously, since the non-collision side does not participate in high-stiffness support, the superposition of ineffective reaction forces is avoided, allowing the structural force to be more concentrated in the actual collision area. This results in a more controllable deceleration process and reduces the risk of lateral deflection or unstable responses. Furthermore, by setting a graded stiffness configuration in the thickness direction, the energy absorption process can unfold gradually from front to back, thereby reducing instantaneous impact loads and improving the smoothness of the energy absorption process.

[0039] Meanwhile, the present invention also discloses a variable stiffness protection system for a crash vehicle, including an array-type crash buffer device installed at the rear of the crash vehicle. The array-type crash buffer device includes an outer shell and a plurality of energy-absorbing units disposed within the outer shell, the energy-absorbing units being arranged in an array. The energy absorption unit includes a fixed energy absorption unit and an adjustable energy absorption unit. The fixed energy absorption unit is fixedly installed inside the outer housing to provide basic buffering capacity. The adjustable energy-absorbing unit is an energy-absorbing component with anisotropic force characteristics. Each adjustable energy-absorbing unit is installed in the outer housing through a rotating connection structure and connected to the drive assembly to rotate and switch between two target angle positions, thereby changing the relative relationship between its main force direction and the collision direction. The outer housing is provided with a limiting or locking structure corresponding to the target angle position, which is used to maintain the angle state of the adjustable energy-absorbing unit after it is switched to the target angle.

[0040] The adjustable energy-absorbing unit changes its main force direction by rotating, thereby switching between a first stiffness mode and a second stiffness mode; a locking structure maintains the switched state to ensure that each energy-absorbing unit maintains a predetermined stiffness configuration when a collision occurs.

[0041] Specifically, the adjustable energy-absorbing unit is an energy-absorbing component with anisotropic force characteristics, exhibiting different compressive stiffness and energy absorption response when compressed in different directions. Preferably, the adjustable energy-absorbing unit adopts a honeycomb structure energy-absorbing component, such as an aluminum honeycomb structure. This honeycomb structure has significant differences in mechanical properties along the hole axis direction and perpendicular to the hole axis direction: when the honeycomb hole axis direction is basically consistent with the collision direction, the structure as a whole exhibits high compressive stiffness, forming a first stiffness mode; when the honeycomb hole axis direction is rotated to a predetermined angle (e.g., about 90°) relative to the collision direction, the structure is more prone to folding and crushing, exhibiting lower compressive stiffness, forming a second stiffness mode. With the above structure, the stiffness state can be switched by changing the spatial orientation of the energy-absorbing unit without changing the material itself. In other embodiments, the anisotropic stress characteristics can also be achieved through the following structures: layered composite structures (e.g., fiber-reinforced composite laminates) with different stiffnesses in the fiber direction and perpendicular direction; oriented folded structures or corrugated structures with different compressive strengths in the unfolding and folding directions; beam / grid structures with different buckling characteristics along the principal stress direction and the transverse direction; and multi-material composite structures that form a directional mechanical response through the spatial arrangement of different materials. Through these different implementation methods, energy-absorbing units with a fixed principal stress direction can be constructed, thereby achieving stiffness mode switching after rotation.

[0042] Meanwhile, the fixed energy-absorbing unit provides basic buffering capacity and can also adopt the above structure or a combination of the above structures, except that it cannot rotate. This ensures that the anti-collision buffer device has basic protective performance under different operating conditions and forms a combined structure with the adjustable energy-absorbing unit, thereby achieving dynamic adjustment function while ensuring system reliability.

[0043] In this embodiment, the energy-absorbing structure inside the array-type anti-collision buffer device is not entirely adjustable, but includes both fixed and adjustable energy-absorbing units. The fixed energy-absorbing units are fixedly installed inside the outer shell and provide basic buffering and load-bearing support under various working conditions. The adjustable energy-absorbing units are located in areas of the anti-collision buffer device that require dynamic response and can switch between different stiffness modes under the action of the drive components to make targeted adjustments according to the collision risk. By combining the fixed and adjustable energy-absorbing structures, the overall drive complexity and manufacturing cost can be reduced while ensuring the reliability of basic protection, and the feasibility of the system in practical engineering applications can be improved.

[0044] Each adjustable energy-absorbing unit is mounted within an outer housing via a rotating connection structure to rotate between two target angle positions around a predetermined axis. The rotating connection structure may include: a shaft and bearing structure; a sleeve-type rotating support structure; or other connection structures capable of achieving stable single-axis rotation. Preferably, the target angle positions are two discrete positions (e.g., approximately 90° apart), corresponding to a first stiffness mode and a second stiffness mode, respectively. The drive assembly is used to drive the energy-absorbing unit to complete the aforementioned angle switching. Its implementation may include, but is not limited to: a motor drive structure (e.g., a DC motor, stepper motor, or servo motor); a geared motor combined with a gear transmission structure; a lead screw / worm gear drive structure; an electromagnetic drive or spring preload release structure (for rapid switching); a pneumatic or hydraulic drive structure. To reduce the impact of collapse, the transmission may employ ropes, belts, or other transmission methods to spatially isolate the power component and the energy-absorbing unit, reducing mutual interference. In some embodiments, a flexible connector, such as a rubber connector or elastic coupling, is provided between the drive assembly and the energy-absorbing unit to absorb the impact load when the energy-absorbing unit rotates to its position and compensate for transmission errors.

[0045] To ensure the energy-absorbing unit remains stable after switching stiffness modes, the outer housing is equipped with a limiting or locking structure corresponding to the target angle position. The locking structure may include: a mechanical limiting buckle; a locking pin or latch structure; or a transmission structure with self-locking characteristics (such as a worm gear mechanism). Through these structures, the energy-absorbing unit can be fixed in position after switching to the target angle, thereby preventing unexpected rotation under impact loads.

[0046] In one embodiment, the array-type anti-collision buffer device includes an adjustable energy-absorbing zone at the front and a fixed energy-absorbing zone at the rear along the collision direction. The adjustable energy-absorbing zone consists of multiple adjustable energy-absorbing units, each of which is an energy-absorbing component with anisotropic force characteristics and can be rotated to different stiffness modes. The fixed energy-absorbing zone consists of multiple fixed energy-absorbing units, which are fixedly installed within the outer housing to continue providing subsequent buffer support after the adjustable energy-absorbing units have completed their initial energy absorption. Through this arrangement, the anti-collision buffer device can achieve targeted dynamic protection in the early stages of a collision using the adjustable energy-absorbing units, while in the later stages, the fixed energy-absorbing units provide stable and continuous basic energy absorption capacity. In other embodiments, the arrangement of the adjustable energy-absorbing units and the fixed energy-absorbing units may also include: staggered arrangement, where adjustable energy-absorbing units and fixed energy-absorbing units are alternately arranged in the same row; partial partitioned arrangement, where adjustable energy-absorbing units are only arranged in the middle or side areas of the anti-collision pad; group control arrangement, where multiple adjustable energy-absorbing units form a group and are controlled by the same drive component; and embedded structure, where partially rotatable energy-absorbing units are embedded in the overall fixed energy-absorbing structure. Through these different arrangement methods, a balance can be struck between control accuracy, cost, and structural complexity according to actual application requirements.

[0047] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for controlling the variable stiffness of a collision avoidance buffer device, characterized in that, The anti-collision buffer device contains multiple energy-absorbing units, of which at least some are adjustable energy-absorbing units and the rest are fixed energy-absorbing units; The adjustable energy absorption unit is a structural component with anisotropic force characteristics and is configured to be controllably rotated to switch between a first stiffness mode and a second stiffness mode, wherein the compressive stiffness of the first stiffness mode along the collision direction is greater than that of the second stiffness mode. The fixed energy-absorbing unit is fixedly installed to provide basic buffering capacity; The control method includes: S0. When a target vehicle behind is detected to meet the preset collision risk conditions, stiffness adjustment is triggered. S1. Determine the collision action area of ​​the target vehicle acting on the anti-collision buffer device under the predicted collision conditions based on the target vehicle's operating status information; S2. Based on the distribution of the collision area in the width direction, the adjustable energy absorption unit is configured with lateral differential stiffness, so that the adjustable energy absorption unit located in the collision area switches to the first stiffness mode, and the adjustable energy absorption unit located outside the collision area maintains the second stiffness mode. S3. Based on the collision intensity characterization parameters of the target vehicle, the adjustable energy absorption units are configured longitudinally in stages, so that at least some of the adjustable energy absorption units near the frontal impact surface are switched to the first stiffness mode. S4. After the target vehicle enters the preset collision time window, the adjustable energy absorption unit that has completed the mode switching is positioned or mechanically locked.

2. The control method according to claim 1, characterized in that, The preset collision risk conditions are determined in the following way: Obtain the offset relationship between the longitudinal axis of the vehicle body center and the single-sided edge of the road when the anti-collision buffer device is stationary; Based on the aforementioned bias relationship and the width range of the anti-collision buffer device, the target monitoring area is determined in the sensing coordinate system; The system tracks the trajectory of a target vehicle behind it and determines the area of ​​impact when the target vehicle enters the target monitoring area.

3. The control method according to claim 2, characterized in that, After the collision zone of the target vehicle is determined, the process includes: Obtain the relative speed and direction of motion information of the target vehicle; In a two-dimensional projection plane established with the rear of the anti-collision buffer device as a reference, the position of the target vehicle within a preset time window is extrapolated according to the relative speed and direction of motion to obtain the predicted profile of the target vehicle. The collision action area is determined based on the overlap position and overlap range between the predicted contour and the anti-collision buffer device in the width direction.

4. The control method according to claim 1, characterized in that, Hierarchical timing control based on the remaining collision time of the target vehicle includes: A first time threshold and a second time threshold are set, wherein the first time threshold is greater than the second time threshold; When the remaining time of the collision is less than or equal to the first time threshold and greater than the second time threshold, the energy absorption unit is controlled to perform stiffness mode switching to complete the lateral differential stiffness configuration and the longitudinal graded stiffness configuration. When the remaining time of the collision is less than or equal to the second time threshold, the stiffness mode switching process of the energy absorption unit is stopped, and the energy absorption unit is subjected to position limiting or mechanical locking to maintain the current stiffness mode. Specifically, when the remaining collision time of the target vehicle is less than or equal to the second time threshold when it is first identified, the position limit or mechanical locking is executed directly without performing the stiffness mode switching.

5. The control method according to claim 1, characterized in that, The lateral differential stiffness configuration and longitudinal hierarchical configuration are collaboratively determined based on the overlap of the predicted collision velocity range and the collision action area, including: Predict the collision speed based on the speed, distance, and deceleration of vehicles behind; When the predicted collision velocity is in the first velocity range, each adjustable energy absorption unit maintains the second stiffness mode. When the predicted collision velocity is in the second velocity range and the predicted collision action area is offset overlap, the adjustable energy absorption units located on the collision side switch to the first stiffness mode, while the adjustable energy absorption units located on the non-collision side maintain the second stiffness mode. When the predicted collision velocity is in the second velocity range and the predicted collision action area is non-biased overlap, each adjustable energy absorption unit adopts a symmetrical stiffness mode configuration along the width direction. When the predicted collision velocity is in the third velocity range, at least some of the adjustable energy-absorbing units near the impact surface switch to the first stiffness mode.

6. A variable stiffness protection system for a collision avoidance vehicle, characterized in that, This includes an array-type crash buffer device installed at the rear of the crash barrier vehicle. The array-type anti-collision buffer device includes an outer shell and multiple energy-absorbing units disposed within the outer shell, wherein the energy-absorbing units are arranged in a multi-row, multi-column array. The energy absorption unit includes a fixed energy absorption unit and an adjustable energy absorption unit. The fixed energy absorption unit is fixedly installed inside the outer housing to provide basic buffering capacity. The adjustable energy-absorbing unit is an energy-absorbing component with anisotropic force characteristics. Each adjustable energy-absorbing unit is installed in the outer housing through a rotating connection structure and connected to the drive assembly to rotate and switch between two target angle positions, thereby changing the relative relationship between its main force direction and the collision direction. The outer housing is provided with a limiting or locking structure corresponding to the target angle position, which is used to maintain the angle state of the adjustable energy-absorbing unit after it is switched to the target angle.

7. The protection system according to claim 6, characterized in that, The adjustable energy-absorbing unit includes an energy-absorbing core with a directional internal structure and a covering shell, wherein the energy-absorbing core is any one or a combination of a honeycomb structure, a layered composite structure, a corrugated folded structure or a grid structure.

8. The protection system according to claim 6, characterized in that, The adjustable energy absorption units are divided into several control groups in rows or columns. Multiple adjustable energy absorption units in each control group are connected to the same drive component through a linkage transmission structure to achieve synchronous angle switching of the energy absorption units in the control group. A flexible connector is provided between the drive component and the adjustable energy absorption unit to buffer the impact load and compensate for transmission errors when the energy absorption unit rotates to the target angle.

9. The protection system according to claim 6, characterized in that, The adjustable energy-absorbing units are arranged in a gapped array inside the outer housing, and adjacent rows of energy-absorbing units are staggered in the width direction to reduce mechanical interference between adjacent energy-absorbing units during rotation switching.

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