Constraint system protection strategy setting method for safety of driver in backward-leaning sitting posture

Abstract

The invention provides a restraint system protection strategy setting method for the safety of a driver in a backward-leaning sitting posture, and relates to the technical field of driving safety protection methods, comprising the following steps: segmenting a driver seat passenger compartment based on a vehicle finite element model, and verifying the effectiveness of a driver side restraint system finite element model; a driver side restraint system pulley model is utilized to complete front rigid barrier collision simulation, the protection effects of a traditional restraint system on a normal sitting posture driver and a backward leaning sitting posture driver are analyzed based on a first dummy model, and multiple restraint system protection strategies are formulated; based on the second dummy model, dummy model damage parameters are output through a simulation experiment, and a constraint protection strategy for ensuring the safety of the backward-tilting driver is obtained. The method has the advantage of realizing an effective protection scheme aiming at the backward inclination posture.

Description

Technical Field

[0001] The present invention relates to the technical field of driving safety protection methods, and in particular to a method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position. Background Art

[0002] As smart cars are gradually put into use in the future, advanced driver assistance systems are constantly being upgraded. Although advanced driver assistance technology reduces the probability of vehicle collisions, it cannot completely prevent collisions.

[0003] Passive safety technology still needs to be continuously improved to provide more comfortable and safe protection for vehicle occupants. Currently, the existing restraint system protection strategy formulation method is relatively simple, and is mostly formulated for drivers with normal postures. Due to the continuous upgrading of advanced driver assistance systems, drivers do not have to maintain a driving posture at all times, and their sitting posture tends to be more like that of a passenger, which makes the reclining sitting posture a common driving style. Existing technology cannot provide comprehensive and effective protection for occupants in advanced driver assistance scenarios. In the gradually developing advanced driver assistance technology, there will be greater reliance on occupant restraint systems that combine pre-collision comfort and post-collision safety.

[0004] Therefore, there is an urgent need to improve the safety restraint method of the automobile to achieve effective protection against the backward tilt posture and improve the safety level of the entire vehicle. Summary of the Invention

[0005] The object of the present invention is to provide a method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position, which can implement an effective protection solution for the reclining posture.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position includes the following steps:

[0008] Based on the vehicle finite element model, the driver's seat passenger compartment was segmented and a dummy model, seat belt, and airbag models were placed in the passenger compartment. A finite element model of the driver's side restraint system was established and its validity was verified.

[0009] A frontal rigid barrier collision simulation was completed using a sled model of the driver-side restraint system. The first dummy model was used to analyze the protective effects of the traditional restraint system on both the driver in a normal and reclined position, and various restraint system protection strategies were developed.

[0010] Based on the second dummy model, the dummy model damage parameters are output through simulation experiments. The protection effects of the traditional restraint system and the developed restraint system protection strategy on rear-leaning seated occupants are compared, and a restraint protection strategy that ensures the safety of rear-leaning drivers is obtained.

[0011] Preferably, the first dummy model adopts a Hybrid III dummy model, and the leg support of the sled model of the driver's side restraint system is cancelled, and the contact between the first dummy model and the brake pedal and accelerator is cancelled.

[0012] Preferably, the second dummy model adopts a THUMS dummy model, and in the driver-side restraint system sled model, the cockpit and the instrument panel are set to be flat, and the steering wheel and pedals are eliminated.

[0013] Preferably, the portion of the seat belt in contact with the dummy model uses a 2D shell unit, the seat belt near the slip ring uses a 1D seatbelt unit, the slip ring friction coefficient is set to 0.15, the retractor force limit level is set to 2800N, and the initial value of the preload force of the pretensioner is set to 2000N.

[0014] Preferably, the initial shape of the airbag is circular with a radius of 250 mm, and is provided with a grid, which is composed of two layers of fabric and provided with exhaust holes.

[0015] Preferably, verifying the validity of the finite element model of the driver side restraint system includes verifying occupant motion response time, verifying occupant damage, and verifying restraint system parameter output.

[0016] Preferably, the occupant injury includes a head acceleration curve, a chest acceleration curve, a neck injury curve and a thigh axial force curve.

[0017] Preferably, the restraint system parameter output includes seatbelt retractor webbing inlet and outlet, retractor outlet seatbelt force and seatbelt lap force curve.

[0018] Preferably, the occupant motion response time includes the moment when the occupant's head contacts the airbag, the moment when the occupant's chest contacts the airbag, and the moment when the steering wheel begins to collapse.

[0019] Preferably, the recording times of the occupant motion response time include 0ms, 22ms, 64ms and 110ms.

[0020] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0021] This invention is applicable to intelligent vehicles. Taking into account the internal structure of the driving vehicle, the airbag, seat belt, dummy model, and seat model with leg support are the main components of the restraint system. These four components are processed to construct a restraint slide model, which helps improve the safety of the protection strategy.

[0022] The present invention incorporates both normal and reclined sitting postures into the simulation for comparison. By studying and simulating the damage values of frontal collisions for occupants in the two sitting postures, it helps to develop a restraint system protection strategy that ensures the safety of drivers reclining backward.

[0023] The present invention compares the restraint system with the traditional restraint system, verifies the protection effect of the restraint strategy through the occupant motion response and damage values, and further verifies the effectiveness of the optimized restraint protection strategy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flowchart of a method for setting a restraint system protection strategy for a leaning driver's safety provided in Example 1;

[0025] Figure 2 This is a diagram of an airbag model of embodiment 1;

[0026] Figure 3 This is a diagram of the safety belt model of Example 1;

[0027] Figure 4 This is a graph of engine top acceleration in Example 1;

[0028] Figure 5 This is a diagram of a vehicle frontal collision scenario in Implementation Column 1;

[0029] Figure 6 The dummy positioning parameter diagram of embodiment 1;

[0030] Figure 7 This is a pre-simulation diagram of the dummy in Implementation 1;

[0031] Figure 8 The occupant motion response diagrams of the actual vehicle and simulation tests for implementation column 1 are shown;

[0032] Figure 9 The damage curve diagram of each part of the occupant in Implementation 1 is shown;

[0033] Figure 10 The safety belt output parameter diagram of embodiment 1;

[0034] Figure 11 Schematic diagram of the contact between the dummy and the seat cushion in embodiment 1;

[0035] Figure 12 Schematic diagram of the contact position between the dummy and the seat belt in embodiment 1;

[0036] Figure 13 Schematic diagram of the occupant's sitting posture restraint state in embodiment 1;

[0037] Figure 14 The damage curves of various parts of occupants in different sitting positions in Example 1 are shown;

[0038] Figure 15 Schematic diagram of the sliding table model of the constraint system for implementing the adjustment of column 1;

[0039] Figure 16 Schematic diagram of occupant forces in embodiment 1;

[0040] Figure 17 Schematic diagram of the motion response of the dummy under different restraint strategies in Implementation Column 1;

[0041] Figure 18 The stress distribution diagram of the occupant's cervical spine under different restraint strategies in column 1 is shown;

[0042] Figure 19 Schematic diagram of the dummy chest compression under different restraint strategies in Implementation 1;

[0043] Figure 20 Schematic diagram of the axial force on the dummy thigh under different constraint strategies implemented in column 1. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0045] Example 1

[0046] This embodiment provides a method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position, including the following steps:

[0047] Establish a finite element model of the driver's side restraint system and verify its effectiveness: Based on the vehicle's finite element model, the driver's seat passenger compartment was segmented. A dummy model, seat belt, and airbag models were placed in the passenger compartment. A finite element model of the driver's side restraint system was established and its effectiveness was verified.

[0048] Develop various restraint system protection strategies: Use the driver-side restraint system sled model to complete a frontal rigid barrier collision simulation. Based on the first dummy model, analyze the protection effect of the traditional restraint system on the driver sitting in the normal position and the driver sitting in the reclining position, and develop various restraint system protection strategies;

[0049] Compare the protection effects of the traditional restraint system and the developed restraint system protection strategy on rear-leaning seated occupants to obtain the restraint protection strategy: Based on the second dummy model, output the dummy model damage parameters through simulation experiments, compare the protection effects of the traditional restraint system and the developed restraint system protection strategy on rear-leaning seated occupants, and obtain the restraint protection strategy that ensures the safety of the rear-leaning driver.

[0050] In this embodiment, the first dummy model adopts a Hybrid III dummy model. Considering that a large-angle leg support may affect the driver's emergency operation, the leg support of the sled model of the driver's side restraint system is eliminated. In addition, the contact between the first dummy model and the brake pedal and accelerator is eliminated to simulate the driver's riding state when the autonomous driving car is driving autonomously.

[0051] On the other hand, the second dummy model adopts the THUMS dummy model, see Figure 13 In the driver-side restraint system sled model, the cockpit and dashboard are set as flat surfaces, and the steering wheel and pedals are eliminated. This setting is because with the development of smart cars, the level of intelligent assisted driving in cars is becoming increasingly advanced. Advanced assisted driving functions will inevitably change the vehicle interior, especially when cars begin to use advanced assisted driving, the driver's role will change to the passenger. As a further solution, the seat mounting points and airbag installation space can be retained, and the driver's frontal airbag is replaced with a larger passenger frontal airbag. The filler material used in the leg restraint is the same as that of the seat, and the filler thickness is set to 60mm. This is to examine the energy absorption performance of the leg restraint in a frontal impact.

[0052] The following is a specific implementation case:

[0053] First, a 50th percentile Hybrid III dummy model was obtained to assess occupant injuries. This example used PRIMER software to build seatbelt and airbag models, along with a seat model with leg support and adjustable mechanisms. The Hybrid III dummy model's sitting posture was adjusted through pre-simulation. The Hybrid III dummy model, seatbelt model, and seat model were placed into the vehicle's driver-side restraint system sled model, which segmented the driver's seat and impacted a rigid barrier head-on at a speed of 56 km / h. Based on the collision restraint evaluation criteria, the output values of the simulation experiment were compared with the injuries to various occupant parts in the actual vehicle test. Some parameters in the restraint system were then output to determine whether the initial values were reasonable, thereby verifying the validity of the finite element model.

[0054] Based on the development of smart cars and the increasingly sophisticated assisted driving functions, and considering that the role of the driver has gradually shifted to that of the passenger, the model in the optimization strategy was adjusted, the pedals were hidden, the instrument panel was flattened, and the steering wheel of the original model was removed. In order to improve the accuracy of the test, the THUMS dummy model was subsequently used to replace the occupant to simulate the motion response and damage in the collision. Based on the system sliding table model constrained by the Hybrid III dummy model, the damage and motion response of the rear-leaning seated occupant in the unadjusted restraint scheme, that is, based on the traditional restraint scheme, were compared through a control test to explore the shortcomings of the traditional restraint system in protecting the rear-leaning driver's safety, and to formulate an optimization strategy for the restraint system accordingly.

[0055] Finally, in order to define the specific damage evaluation indicators for each part, the THUMS dummy model damage is used to replace the occupant damage. Through simulation experiments, relevant parameters are output, and the traditional restraint system is used as the control group and compared with the new restraint strategy to analyze the protection effect of the rear-leaning seated occupants. Finally, the restraint protection strategy that can ensure the safety of the rear-leaning driver is determined. The evaluation indicators of the occupant's damage to each part refer to the various provisions in CNCAP (2024 edition). At present, for the evaluation of head injuries, the HIC based on head acceleration is used. 36ms Evaluation indicators are accepted by most people. Commonly used occupant injury indicators are shown in Table 1:

[0056] Table 1 Dummy head injury values

[0057]

[0058] In the model selection, Figure 11 As shown in the figure, the hip and upper torso of the Hybrid III dummy model are discontinuous, so the seat belt slides into the dummy's abdomen. Figure 12As shown, excessive belt force can cause negative volume in the abdominal mesh, prematurely ending the crash simulation. Furthermore, the Hybrid III dummy's hip and leg adjustments, when adjusted at large angles, cannot accommodate a reclined sitting position, resulting in interference during the adjustment process and an inability to realistically simulate occupant-seat contact. Finally, the Hybrid III dummy's high spinal stiffness also affects the occupant's upper torso motion response. The THUMS dummy, however, offers a higher degree of biofidelity, both in appearance and internal structure. Therefore, it will be used in place of the occupant to simulate motion responses and injuries in crashes.

[0059] like Figure 13 As shown in the figure, based on the Hybrid III dummy's restraint system slide model, occupant restraint state models for normal and reclined positions were constructed. To investigate safety, the leg support was removed, and the dummy's contact with the brake and accelerator pedals was eliminated to simulate the driver's driving state during autonomous vehicle operation. For the reclined dummy, the hands were naturally placed on the thighs. A 56 km / h frontal rigid barrier collision was performed to demonstrate the damage to the occupant in this reclined position. Figure 15 Schematic diagram of the sliding table model of the adjusted constraint system.

[0060] The model related to this embodiment is further explained below.

[0061] As a preferred solution, the part of the seat belt that contacts the dummy model uses a 2D shell unit, the seat belt near the slip ring uses a 1D seatbelt unit, the slip ring friction coefficient is set to 0.15, the retractor force limit level is set to 2800N, and the initial value of the preload force of the pretensioner is set to 2000N.

[0062] In addition, the initial shape of the airbag is circular with a radius of 250 mm, and is provided with a grid, which is composed of two layers of fabric and exhaust holes.

[0063] When modeling, Figure 2 As shown in the figure, the airbag model is built using PRIMER and HyperMesh software, and the Thin Fold method is used to simulate the airbag inflation process. The accuracy of the airbag deployment and inflation process is ensured by setting appropriate contact conditions and material properties. Figure 3 As shown in the figure, the seat belt model is modeled using PRIMER software, using 2D and 1D units to simulate the performance of the seat belt in different parts, and realizing pre-tensioning and force limiting functions to optimize occupant protection.

[0064] It is worth noting that in one implementation case, the vehicle finite element model includes 1,086 parts including the complete body structure, engine, chassis, seat interior, etc., including 2,255,361 nodes and 2,257,280 units. The deviation between the model and the actual vehicle in terms of mass, moment of inertia, center of gravity position, etc. does not exceed 3%, which is within the acceptable error range. By comparing with the actual collision test data, the acceleration response of the model when simulating a frontal collision at a speed of 56 km / h is highly consistent with the test results of the actual vehicle. Figure 4 As shown, the accuracy of the vehicle finite element model is verified.

[0065] According to the solution of this embodiment, it can be seen that this embodiment first divides the driver's seat and passenger compartment based on the vehicle finite element model. Figure 5 As can be seen from the vehicle frontal collision scenario shown, the overall structure of the vehicle driver's cabin is intact when a frontal collision occurs, and the driver's living space has not changed. If the finite element model of the entire vehicle is selected, not only can the accuracy of the simulation results not be guaranteed, but the calculation amount of the finite element model will also be increased. Therefore, this embodiment performs segmentation and only extracts the driver's cabin, which can not only reduce the calculation amount but also ensure the accuracy of the simulation. At the same time, key components such as the steering wheel, brake pedal, and seat are retained in the model. The seat belts, airbags, and dummies are placed in the passenger cabin for collision and comfort tests. In addition, a seat model with leg support can be established to simulate the comfort performance under different passenger postures. The finite element method of the vehicle finite element model of this embodiment mainly uses HyperView and HyperGraph for processing simulation data. HyperView can display the impact of the passenger's limbs and other objects during the collision, and can also display the stress and strain cloud map generated by the flexible body. The simulation data obtained from the experiment can be plotted into an intuitive curve graph using HyperGraph. This embodiment uses a combination of two software to make the results more intuitive and accurate. In the experiment of this embodiment,,

[0066] In addition, the dummy positioning parameter diagram of this embodiment can be found in Figure 6 , refer to the dummy simulation diagram Figure 7 .

[0067] As a specific preferred solution, verifying the validity of the finite element model of the driver-side restraint system includes verifying the occupant motion response time, verifying the occupant damage and verifying the restraint system parameter output.

[0068] Furthermore, the occupant injury includes a head acceleration curve, a chest acceleration curve, a neck injury curve and a thigh axial force curve.

[0069] In addition, the restraint system parameter output includes the seatbelt retractor webbing in and out amount, the retractor outlet seatbelt force and the seatbelt lap force curve.

[0070] At the same time, the occupant motion response time includes the moment when the occupant's head contacts the airbag, the moment when the occupant's chest contacts the airbag, and the moment when the steering wheel begins to collapse.

[0071] Furthermore, the recording times of the occupant motion response time include 0ms, 22ms, 64ms and 110ms.

[0072] In the specific experiment, this embodiment uses the method of comparing the results of real car collision test with the simulation test to verify the effectiveness of the model. Figure 8 The figure below shows the occupant's motion response at different moments in the real vehicle test and simulation test. By comparing the two motion behaviors, the accuracy of the simulation model in reproducing the actual collision process can be verified.

[0073] In the process of handling occupant injury, an example of this embodiment is Figure 9 As shown, the NCAP protocol outputs injury curves for various occupant parts, including head acceleration, neck injury, chest acceleration, and thigh axial force. The following conclusions can be drawn: Based on a comparative analysis of the NCAP protocol simulation test results and the vehicle test results, the injury curves for various occupant parts show some similarity, but also some differences. Specifically, the peak value of the head acceleration is consistent with the vehicle test results, but slightly higher than the vehicle test results; the growth trend of the chest acceleration is similar, with the peak value in the simulation test slightly lower than the vehicle test results; the peak value and trend of the neck injury are relatively close, but the peak value in the simulation test shows a lag; the peak trend of the thigh axial force is similar, but the phase difference is significant, which may be related to the thigh position in the initial collision. These results indicate that the simulation and vehicle tests are generally consistent in the injury characteristics of various parts, but there are some differences in the specific peak values and phases.

[0074] Verifying the output of the constraint system parameters is mainly to check whether the initial values of the constraint system parameters in the model are reasonable. Figure 10 As shown in the figure, the output curves include the seatbelt retractor webbing in and out, the seatbelt force at the retractor outlet, and the seatbelt lap force. Overall, the effectiveness of the sliding platform model was verified by comparing key indicators such as motion response, damage curves, and restraint system parameters between the actual vehicle test and the simulation test.

[0075] After outputting the damage curve, we can see that Figure 14 The rearward sitting posture has a great influence on the movement response of the occupant's head; the neck injury of the occupant in the rearward sitting posture is quite different from that of the occupant in the normal sitting posture; the axial force of the thigh of the occupant in the rearward sitting posture is greater than that of the occupant in the normal sitting posture, indicating that the collision between the legs of the occupant in the rearward sitting posture and the dashboard is more intense, that is to say, the traditional restraint system protection strategy cannot provide effective protection for the occupants in the rearward sitting posture.

[0076] Figure 16 Schematic diagram of occupant forces in embodiment 1;

[0077] The main forces on the occupants in the horizontal direction during a collision are as follows: Figure 16 As shown in the figure, during a collision, due to the action of inertia, the occupant will move forward and collide with the dashboard. In order to prevent this from happening, the various components of the restraint system need to provide reasonable restraints for the occupant. This article restrains the movement of the hips by increasing the flexible restraint of the legs; removes the seat belt to prevent the seat belt from slipping or concentrated load causing additional damage to the occupant sitting in the rear-leaning position; and uses a larger front airbag to replace the seat belt to provide restraint for the occupant's upper torso.

[0078] In order to more intuitively see the protection effect of the optimization strategy designed in this paper, refer to Table 2, which lists the configurations of the four restraint system protection strategies. The control group is the traditional restraint system. It should be noted that for the three optimized experimental groups, the driver's role is changed to the passenger.

[0079] Table 2 Restraint system protection strategy

[0080]

[0081] Based on the above constraint strategy, simulation comparison is performed, and the results are as follows:

[0082] The dummy's motion response under the four restraint system protection strategies is as follows: Figure 17 As shown, in the control group, restraint strategies 1, and 2, the dummy's pelvic anterior displacement was significantly greater than in restraint strategy 3. The lack of a knee restraint in the control group and restraint strategy 1 resulted in a significant pelvic displacement. However, in restraint strategy 2, despite the addition of a knee restraint, the dummy's pelvic anterior displacement remained significant. Furthermore, the dummy's head, lacking a seatbelt, impacted the windshield, causing the crash simulation to end at 82ms. In restraint strategy 3, the dummy's pelvic anterior displacement was minimal, and at 120ms, the dummy had already experienced significant rebound. Overall, in restraint strategies 1 and 2, the dummy significantly deformed the front of the seat, showing a clear tendency to dive downward. In restraint strategy 3, the knee restraint further prevented the occupant's pelvic from diving downward by limiting knee displacement.

[0083] Table 3 describes the HIC of the dummy in the control group and restraint strategy 1 36msThe values are relatively high, namely 860 and 980 respectively, which are very close to the damage tolerance limit of 1000. Although the HIC36ms value of the dummy in restraint strategy 2 is the smallest, it is obviously because the simulation ended early due to a collision between the head and the front windshield. The head injury of the dummy in restraint strategy 3 is lower, and its HIC36ms value is 610, indicating that this restraint strategy provides better protection for the occupants.

[0084] Table 3 Comparison of damage to various parts of the dummy under different restraint strategies

[0085]

[0086] In general, it is more feasible to adopt reasonable restraints on the dummy's upper torso and use seat belts or larger airbags to restrict its movement. This can effectively prevent the dummy's head from colliding with the car interior and reduce injuries to the occupants.

[0087] As an implementable method, an evaluation parameter K can be used to obtain the excellence of each strategy, for example:

[0088] K=a*HIC+b*ne+c*br+d*ri+e*le;

[0089] Among them, HIC, ne, br, ri and le are head injury index, maximum cervical spine stress, chest compression, maximum rib strain and thigh axial force, respectively. a, b, c, d and e are corresponding weights, which can be determined based on the actual importance of each part.

[0090] Figure 18 The study shows that restraint strategy 2 produces the lowest maximum stress in the cervical spine, at 1.66 MPa. However, this restraint strategy resulted in the dummy colliding with the windshield, a clearly undesirable outcome. The maximum stress in the cervical spine for the control group, restraint strategies 1, and 3 was 1.89 MPa, 2.03 MPa, and 1.84 MPa, respectively. This indicates that the maximum stress in the control group, restraint strategies 1, and 3 all occurred at C3 of the cervical spine, and the timing of this peak occurred near the second peak of tension, indicating that seatbelt restraint increases the risk of cervical spine injury.

[0091] Figure 19It is described that in restraint strategy 2, the dummy's chest did not compress, but expanded, and its maximum expansion reached 38mm. In the control group and restraint strategy 1, the dummy's chest compression was 19.4mm and 19.9mm, respectively. In restraint strategy 3, the dummy's chest compression was the smallest, at 16.1mm. In the control group and restraint strategy 1, the maximum plastic strain of the dummy's ribs was 5%, and the high-risk areas of the dummy's ribs were significantly more than those in the control group. In restraint strategy 2, the maximum plastic strain of the dummy's ribs was 1%. In restraint strategy 3, the maximum plastic strain of the dummy's ribs was 4.8%, as shown below. Figure 18 As shown in the figure, the plastic strain in the dummy's ribs is concentrated in the upper ribs, with the maximum plastic strain occurring closer to the dummy's shoulders. This suggests that the primary cause of the dummy's chest rib fractures is the restraint of the seatbelt shoulder straps. Furthermore, the larger airbag also increases the risk of rib fractures.

[0092] Figure 20 The study describes that in the control group and restraint strategy 1, both models lacked knee restraints, and their thigh axial forces were 6501N and 6629N, respectively, with a difference of no more than 2%. In restraint strategy 2, the dummy's thigh axial force was the highest, reaching 6927N, exceeding the control group by 6.6%. In restraint strategy 3, the dummy's thigh axial force was the lowest, at 5136N. Based on this, the damage to the dummy's thigh under restraint strategies 1 and 2 was essentially the same. In restraint strategy 2, the dummy's forward displacement was the greatest due to its lack of seatbelt restraint, resulting in the greatest axial force on the thigh. In restraint strategy 3, the dummy, restrained by both the leg restraint and the seatbelt, experienced the least forward displacement, resulting in the smallest thigh axial force and minimal thigh damage.

[0093] Based on the simulation results and referring to the damage sustained by the dummy under the four restraint strategies described in Table 3, restraint strategy 1 resulted in higher overall damage to the dummy than the control group. Strategy 2 achieved minimum head HIC36ms and maximum rib strain, but the dummy collided with the windshield during the collision, making this restraint strategy unacceptable. Strategy 3 showed reduced damage to all dummy parts compared to the control group. In summary, restraint strategy 3 provides better occupant protection than the other restraint strategies.

[0094] In other words, based on the analysis results of the above cases, it can be seen that the restraint strategy 2 without the seat belt cannot complete the complete simulation. At 82ms, the occupant's head collides with the car's front windshield, causing serious head injury and more serious personal injury. Therefore, this optimization strategy is not adopted. Although the seat belt will increase the risk of cervical spine and rib injuries, the experimental results show that the injuries are all within the human body's tolerance range. Taking all factors into consideration, the seat belt is crucial in the arrangement of the restraint system protection strategy. Comparing the simulation results of optimization strategy 1 and optimization strategy 3, it can be seen that strategy 3 with the addition of a knee restraint device has a significant reduction in the occupant's upper body movement displacement, head injury, cervical spine injury and leg injury. The setting of the knee restraint device limits the displacement of the occupant during the collision and shares the force borne by the seat belt, thereby achieving the key to reducing occupant injuries. key role; in the simulation of head injury, by comparing the control group and optimization strategy 1, it can be seen that in the control group, the occupant's head contacts the airbag too late when a collision occurs, causing the occupant's head to collide with the steering wheel first; in optimization strategy 1, since the steering wheel is cancelled and a larger airbag is installed in its original position, the occupant's head is converted to collide with the airbag during a collision. Although strategy 1 increases the displacement of the occupant's upper torso, which increases the injury indicators explored in this article, it avoids a hard collision with the steering wheel; optimization strategy 3 adds a knee restraint device on the basis of strategy 1. The test results show that its protection effect is improved in all directions; it can be further seen that in the restraint protection strategy for rear-leaning occupants, the simultaneous installation of seat belts, larger airbags and knee restraints can provide effective protection for occupants in a rear-leaning sitting position.

[0095] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position, characterized in that: The following steps are involved: Based on the vehicle finite element model, the driver's seat passenger compartment was segmented and a dummy model, seat belt, and airbag models were placed in the passenger compartment. A finite element model of the driver's side restraint system was established and its validity was verified. A frontal rigid barrier collision simulation was completed using a sled model of the driver-side restraint system. The first dummy model was used to analyze the protective effects of the traditional restraint system on both the driver in a normal and reclined position, and various restraint system protection strategies were developed. Based on the second dummy model, the dummy model damage parameters are output through simulation experiments. The protection effects of the traditional restraint system and the developed restraint system protection strategy on rear-leaning seated occupants are compared, and a restraint protection strategy that ensures the safety of rear-leaning drivers is obtained.

2. The method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position according to claim 1, characterized in that: The first dummy model adopts a Hybrid III dummy model, and the leg support of the sled model of the driver's side restraint system is cancelled, and the contact between the first dummy model and the brake pedal and accelerator is cancelled.

3. The method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position according to claim 2, characterized in that: The second dummy model adopts a THUMS dummy model. In the driver-side restraint system sled model, the cockpit and instrument panel are set to be flat, and the steering wheel and pedals are removed.

4. The method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position according to claim 1, characterized in that: The portion of the seat belt that contacts the dummy model uses a 2D shell unit, and the seat belt near the slip ring uses a 1D seatbelt unit. The slip ring friction coefficient is set to 0.15, the retractor force limit level is set to 2800N, and the initial value of the preload force of the pretensioner is set to 2000N.

5. The method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position according to claim 1, characterized in that: The initial shape of the airbag is circular with a radius of 250 mm and is provided with a grid. The grid is composed of two layers of fabric and is provided with exhaust holes.

6. The method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position according to claim 1, characterized in that: Verifying the validity of the finite element model of the driver side restraint system includes verifying the occupant motion response time, verifying the occupant damage and verifying the restraint system parameter output.

7. The method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position according to claim 6, characterized in that: The occupant injury includes a head acceleration curve, a chest acceleration curve, a neck injury curve and a thigh axial force curve.

8. The method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position according to claim 6, characterized in that: The restraint system parameter output includes the seat belt retractor webbing in and out amount, the retractor outlet seat belt force and the seat belt lap force curve.

9. The method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position according to claim 6, characterized in that: The occupant motion response time includes the moment when the occupant's head contacts the airbag, the moment when the occupant's chest contacts the airbag, and the moment when the steering wheel begins to collapse.

10. The method for setting a restraint system protection strategy for the safety of a driver in a reclining sitting position according to claim 9, characterized in that: The recorded times of the occupant motion response time include 0ms, 22ms, 64ms and 110ms.

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