A vehicle safety comprehensive evaluation method and system
Patent Information
- Application Number
- CN202310477597.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-04-28
- Publication Date
- 2026-10-09
- Estimated Expiration
- 2043-04-28
AI Technical Summary
而车辆在发生失稳前，一般会先具备非线性特征，因此，现有技术中缺乏一种对车辆安全进行全面、综合评价的方法
[0034] This invention evaluates the nonlinearity of a vehicle based on its actual state and expected driving state. It comprehensively assesses and quantifies the vehicle's safety characteristics under different speeds and road conditions from the perspective of the vehicle itself, considering the vehicle's state safety boundary and the expected driving state. It constructs a comprehensive vehicle safety evaluation index that considers the vehicle's stability and nonlinearity, helping the vehicle stability control system to detect instability trends in advance, correct the vehicle's posture in a timely manner, avoid loss of vehicle control as much as possible, and ensure driving safety.
Smart Images
Figure CN116401893B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of safety risk assessment technology, specifically relating to a comprehensive vehicle safety evaluation method and system. Background Technology
[0002] Vehicle handling stability not only affects the driver's experience but also ensures safe driving at high speeds. Therefore, vehicle handling stability testing is an essential part of vehicle development. However, existing vehicle handling stability tests are often limited to single test conditions, failing to comprehensively analyze the adaptability of evaluation indicators under different speeds and road adhesion conditions. The construction of evaluation indicators mainly focuses on assessing vehicle stability, using qualitative or quantitative indicators to describe the degree of stability, neglecting the nonlinear characteristics of the vehicle's tendency to become unstable. Before instability occurs, vehicles generally exhibit nonlinear characteristics; therefore, current technology lacks a comprehensive method for evaluating vehicle safety. Summary of the Invention
[0003] To address the shortcomings of the existing technology, this invention discloses a comprehensive vehicle safety evaluation method, which adopts the following technical solution:
[0004] A comprehensive vehicle safety evaluation method includes the following steps:
[0005] Based on the actual vehicle state and the vehicle state safety boundary value, a vehicle stability index characterizing the vehicle's stability level is calculated; based on the actual vehicle state and the expected driving state, a vehicle nonlinearity index characterizing the vehicle's nonlinearity is calculated; based on the vehicle stability index and the vehicle nonlinearity index, a comprehensive vehicle safety evaluation index characterizing the vehicle's overall safety characteristics is constructed.
[0006] Furthermore, the expression for the comprehensive vehicle safety evaluation index is as follows:
[0007] Cost cs =w st *Cost s +w nl *Cost nl
[0008] Cost cs For vehicle safety comprehensive evaluation indicators, w st To stabilize index weights, Cost s For vehicle stability index, w nl Non-linear exponential weights, Cost nl This is the nonlinear index of the vehicle.
[0009] Furthermore, the actual state of the vehicle is determined by the actual yaw rate w and the actual lateral acceleration a. yCharacterization.
[0010] Furthermore, the vehicle state safety boundary value is determined by the yaw rate safety boundary value w. s Lateral acceleration safety boundary value a ys Characterization;
[0011] The vehicle stability index is calculated using the following formula:
[0012]
[0013] Furthermore, the yaw rate safety boundary value w s Lateral acceleration safety boundary value a ys Calculated by the following formula:
[0014] a ys =0.85 μg
[0015]
[0016] Among them, V x Let μ be the longitudinal velocity of the vehicle, μ be the road adhesion coefficient, and g be the acceleration of the center of gravity.
[0017] Furthermore, the expected driving state is determined by the expected yaw rate w. l Expected lateral acceleration a yl Characterization;
[0018] The vehicle nonlinearity index is calculated by the following formula:
[0019]
[0020] Furthermore, the stability index weight and nonlinear index weight are adaptively adjusted based on the vehicle state safety boundary value, the actual vehicle state, and the expected driving state.
[0021] Furthermore, the adaptive adjustment method is as follows:
[0022] Let S be the area of the rectangle of state variables enclosed by the vehicle state safety boundary value; let S1 be the area of the rectangle of state variables enclosed by the actual vehicle state; let S2 be the area of the rectangle of state variables enclosed by the deviation between the actual vehicle state and the expected driving state; let W1 be the initial value of the stability index weight and W2 be the initial value of the nonlinear index weight.
[0023]
[0024]
[0025] The weights of the stable exponent and the nonlinear exponent are normalized:
[0026]
[0027]
[0028] Furthermore, the actual state of the vehicle is perceived by sensors, and the expected driving state is generated through driving data calibration or the vehicle stability control system.
[0029] This invention also discloses a comprehensive vehicle safety evaluation system, including...
[0030] The vehicle stability index calculation module is configured to calculate the vehicle stability index, which characterizes the degree of vehicle stability, based on the actual vehicle state and the vehicle state safety boundary value.
[0031] The vehicle nonlinear index calculation module is configured to calculate the vehicle nonlinear index, which characterizes the degree of vehicle nonlinearity, based on the actual state of the vehicle and the expected driving state.
[0032] The vehicle safety comprehensive evaluation index construction module is configured to construct a vehicle safety comprehensive evaluation index that characterizes the overall safety characteristics of a vehicle based on the vehicle stability index and the vehicle nonlinearity index.
[0033] By adopting the above technical solution, the beneficial effects of the present invention are as follows:
[0034] This invention evaluates the nonlinearity of a vehicle based on its actual state and expected driving state. It comprehensively assesses and quantifies the vehicle's safety characteristics under different speeds and road conditions from the perspective of the vehicle itself, considering the vehicle's state safety boundary and the expected driving state. It constructs a comprehensive vehicle safety evaluation index that considers the vehicle's stability and nonlinearity, helping the vehicle stability control system to detect instability trends in advance, correct the vehicle's posture in a timely manner, avoid loss of vehicle control as much as possible, and ensure driving safety. Attached Figure Description
[0035] Figure 1 This is a flowchart of a vehicle safety comprehensive evaluation method according to an embodiment of the present invention;
[0036] Figure 2 This is a schematic diagram illustrating the construction of the comprehensive vehicle safety evaluation index of the present invention;
[0037] Figure 3 This is a schematic diagram illustrating the construction of the stable index weights in this invention;
[0038] Figure 4 This is a schematic diagram illustrating the construction of the nonlinear exponential weights in this invention;
[0039] Figure 5 This is a schematic diagram of the vehicle trajectory of the slow incremental steering test vehicle in Example 1. Detailed Implementation
[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0041] like Figure 1 As shown in the figure, this embodiment discloses a comprehensive vehicle safety evaluation method, including the following steps:
[0042] S1. Based on the actual vehicle state and the vehicle state safety boundary value, calculate the vehicle stability index Cost, which characterizes the degree of vehicle stability. s ;
[0043] S2. Based on the actual vehicle state and the expected driving state, calculate the vehicle nonlinearity index Cost, which characterizes the degree of vehicle nonlinearity. nl ;
[0044] S3, based on vehicle stability index Cost s and vehicle nonlinear index Cost nl To construct a comprehensive vehicle safety evaluation index, Cost, that characterizes the overall safety characteristics of a vehicle. cs .
[0045] Under good road conditions, a vehicle's handling response characteristics generally match driving expectations. However, as driving conditions deteriorate, tires are prone to saturation, leading to a surge in vehicle nonlinearity. Existing vehicle safety evaluation methods mostly assess vehicle stability without considering the impact of vehicle nonlinearity on driving safety. This invention evaluates vehicle nonlinearity based on the vehicle's actual state and the expected driving state. By considering the vehicle's safety boundaries and the expected driving state, it comprehensively quantifies and evaluates vehicle safety characteristics under different speeds and road conditions. This constructs a comprehensive vehicle safety evaluation index that considers both vehicle stability and nonlinearity, helping the vehicle stability control system to detect instability trends in advance, correct vehicle posture promptly, minimize loss of control, and ensure driving safety.
[0046] The steps of the comprehensive vehicle safety evaluation method are described in detail below:
[0047] S1. Based on the actual vehicle state and the vehicle state safety boundary value, calculate the vehicle stability index Cos t, which characterizes the degree of vehicle stability. s ;
[0048] like Figure 2As shown, during vehicle operation, the vehicle is limited by the ground adhesion force. As the tire force approaches the ground adhesion force, the wheels tend to saturate, and the vehicle's state variables approach their limits. At this point, the vehicle is close to instability, exhibiting poor stability and is prone to fishtailing or skidding. The vehicle's yaw rate and lateral acceleration are also prone to sudden changes. Therefore, at high speeds, the yaw rate of a car should not be too high; otherwise, dangerous behaviors such as skidding are likely to occur. Accordingly, this invention constructs a safety boundary based on yaw rate and lateral acceleration. By calculating the vehicle stability index based on the distance between the vehicle's actual state and the vehicle's safety boundary, the degree of vehicle stability is determined.
[0049] This invention is based on road adhesion conditions and uses a yaw rate safety boundary value w. s Lateral acceleration safety boundary value a ys Characterizing the vehicle's safety boundary values; using the vehicle's actual yaw rate w and actual lateral acceleration a. y It represents the actual state of the vehicle.
[0050] Among them, the vehicle's actual yaw rate w and actual lateral acceleration a y It can be estimated that, from an accuracy perspective, it is preferable to sense through sensors, such as through IMU sensors.
[0051] Lateral acceleration safety boundary value a ys yaw rate safety boundary value w s The following formula is used to derive:
[0052] a ys =0.85 μg
[0053]
[0054] In the formula, μ is the road adhesion coefficient, g is the acceleration of the center of gravity, and V is the acceleration of the center of gravity. x The longitudinal speed of the vehicle can be estimated from the acceleration and wheel speed (acceleration can be detected by IMU sensor, and wheel speed can be detected by wheel speed sensor). There are already mature estimation methods, which will not be elaborated here.
[0055] Vehicle Stability Index Cost s The following formula is used to derive:
[0056]
[0057] When the actual vehicle condition is within the safe boundary range, the stability index is negative; as the vehicle condition approaches the safe boundary, the tires tend to saturate, the vehicle is prone to instability, and the stability index tends to 0; when the vehicle condition exceeds the safe boundary range, the stability index is positive, and the vehicle is prone to instability.
[0058] S2. Based on the actual vehicle state and the expected driving state, calculate the vehicle nonlinearity index Cost, which characterizes the degree of vehicle nonlinearity. nl ;
[0059] Under good road conditions, a vehicle's handling response characteristics generally meet expectations. However, as driving conditions deteriorate, tires tend to saturate, leading to a surge in vehicle nonlinearity. When the vehicle approaches instability, the yaw rate and lateral acceleration responses deviate significantly from driving expectations. Therefore, this invention proposes a nonlinearity index based on the deviation between the actual and expected vehicle states to express the degree of vehicle nonlinearity.
[0060] Among them, the expected driving state is determined by the expected yaw rate w. l Expected lateral acceleration a yl Characterization;
[0061] Vehicle nonlinear index Cost nl The following formula is used to derive:
[0062]
[0063] Similarly, the vehicle's actual yaw rate w and actual lateral acceleration a y Preferred sensing method: yaw rate w (expected by the driver) l And the expected lateral acceleration a yl It can be generated through driving data calibration or vehicle stability control systems, such as through the ESP (Electronic Stability Program) system.
[0064] When the actual state of the vehicle is close to the expected driving value, the nonlinearity index tends to 0; as the nonlinearity of the vehicle increases, the actual state of the vehicle deviates significantly from the expected state, and the nonlinearity index becomes positive.
[0065] S3, based on vehicle stability index Cost s and vehicle nonlinear index Cost nl To construct a comprehensive vehicle safety evaluation index, Cost, that characterizes the overall safety characteristics of a vehicle. cs .
[0066] This invention comprehensively considers the vehicle's stability and nonlinearity, and the expression for the comprehensive vehicle safety evaluation index is as follows:
[0067] Cost cs =w st *Cost s +w nl *Cost nl
[0068] In the formula, Cost cs For vehicle safety comprehensive evaluation indicators, wst To stabilize the index weights, w nl The weights are non-linear exponential weights, where the stable exponential weights w st Nonlinear exponential weight w nl You can choose based on experience or through trial and error.
[0069] When the comprehensive vehicle safety evaluation index is negative, it indicates that the vehicle has a low degree of nonlinearity, the nonlinearity index is close to 0, the actual state of the vehicle is far from the safety boundary value, the vehicle body stability is strong, and the overall safety characteristics of the vehicle are good. When the comprehensive evaluation index is positive, the vehicle has a significant degree of nonlinearity, the actual state of the vehicle is close to or exceeds the safety boundary value, the wheels tend to be saturated, and the vehicle is prone to instability.
[0070] The vehicle safety comprehensive evaluation index proposed in this invention comprehensively quantifies and evaluates vehicle safety based on both stability and nonlinearity. A negative value indicates a safe and stable vehicle; a positive value close to 0 indicates a relatively safe vehicle; and a value exceeding 0.19 indicates a sharp increase in nonlinearity and a significant decrease in safety and stability. Based on this, driver assistance systems can establish tiered warning systems to remind drivers to take appropriate safety measures such as slowing down to avoid loss of vehicle control. In human-machine co-driving scenarios, this index can enrich driving control switching strategies and help determine the timing of intervention by the autonomous driving control system. For fully autonomous driving systems, it can serve as a theoretical basis for decision-making systems, improving vehicle driving safety.
[0071] In the current construction of comprehensive vehicle safety evaluation indicators, in accordance with driving needs, the emphasis is on the degree of vehicle state response and the accuracy of vehicle control in the safe zone, with an increased weight for the nonlinear index. In the unstable zone, the emphasis is on the degree of vehicle stability and the requirement that the vehicle should be as stable as possible, with an increased weight for the stability index. Relying on experience or trial and error requires a significant amount of time and effort to calibrate the corresponding weight values under different operating conditions. The setting of these weight values is highly subjective and relatively fixed, with weight values fluctuating under different operating conditions. Therefore, this invention, based on the vehicle state safety boundary value, the actual vehicle state, and the expected driving state, objectively and adaptively adjusts these two weight values, achieving a smooth transition of weight values under various operating conditions and thus expanding its applicability.
[0072] Therefore, this invention provides a method for adaptively adjusting the stability index weight w based on the vehicle state safety boundary value, the actual vehicle state, and the expected driving state. st Nonlinear exponential weight w nl Method:
[0073] The vehicle state safety boundary value (i.e., the yaw rate boundary value w) is used to define the vehicle state safety boundary value. s and lateral acceleration boundary value a ysThe area of the rectangle enclosed by the actual vehicle state is denoted as S; the area of the rectangle enclosed by the actual vehicle state and the expected driving state is denoted as S1; the area of the rectangle enclosed by the deviation between the actual vehicle state and the expected driving state is denoted as S2. Figure 3 A diagram illustrating the stable index weights; Figure 4 This is a schematic diagram of non-linear exponential weighting.
[0074] Let W1 be the initial value of the stable exponential weight and W2 be the initial value of the nonlinear exponential weight.
[0075]
[0076]
[0077] Normalize the weights of the stable exponent and the nonlinear exponent by limiting the sum of the two weights to 1. After processing:
[0078]
[0079]
[0080] The stability index weights and nonlinear index weights assigned using the above method can vary with road adhesion conditions. On high-friction surfaces, where skidding and other risks are less likely to occur, the emphasis is often on ensuring the vehicle's response matches driving expectations to avoid collisions due to excessive response deviations. Under these conditions, the nonlinear index weights assigned by the adaptive adjustment method are higher, resulting in a vehicle safety comprehensive evaluation index that better reflects actual driving conditions on high-friction surfaces. Conversely, on low-friction surfaces, tires are prone to saturation, and drivers are more likely to become overly tense and operate improperly, leading to vehicle instability. Therefore, the comprehensive evaluation emphasizes vehicle stability characteristics, and under these conditions, the stability index weights assigned by the adaptive adjustment method are higher, resulting in a vehicle safety comprehensive evaluation index that better reflects actual driving conditions on low-friction surfaces. Adaptively adjusting the weight values based on the vehicle's actual state and road conditions allows for a smooth transition of vehicle safety comprehensive evaluation index weight values across multiple operating conditions, thus expanding its applicability.
[0081] This invention also discloses a comprehensive vehicle safety evaluation system, including a vehicle stability index calculation module, a vehicle nonlinear index calculation module, and a comprehensive vehicle safety evaluation index construction module. The vehicle stability index calculation module is configured to calculate a vehicle stability index characterizing the degree of vehicle stability based on the actual vehicle state and the vehicle state safety boundary value. The vehicle nonlinear index calculation module is configured to calculate a vehicle nonlinear index characterizing the degree of vehicle nonlinearity based on the actual vehicle state and the expected driving state. The comprehensive vehicle safety evaluation index construction module is configured to construct a comprehensive vehicle safety evaluation index characterizing the comprehensive safety characteristics of the vehicle based on the vehicle stability index and the vehicle nonlinear index.
[0082] Example 1
[0083] This embodiment uses simulation data as a specific implementation case of the comprehensive vehicle safety evaluation method. In this simulation case, the vehicle state quantities, including the vehicle's longitudinal velocity, yaw rate, and lateral acceleration, are all known quantities.
[0084] This embodiment uses a slow incremental steering test as the test condition. The basic test method for this condition is as follows: the vehicle maintains a constant speed, and the steering wheel angle increases in increments of 2 degrees per second. As the steering angle increases, the radius of curvature of the vehicle trajectory continuously decreases, and the vehicle state transitions from a linear region to a nonlinear region. Ultimately, the vehicle trajectory exhibits a spiral shape, such as... Figure 5 As shown. Based on this, considering the significant impact of vehicle speed and road adhesion conditions on vehicle stability and nonlinearity, to effectively induce nonlinear states in the vehicle and further enrich the experimental content, slow incremental steering tests were conducted under different vehicle speeds and road adhesion conditions. The tests were mainly divided into two categories: the same vehicle speed under different road adhesion conditions and the same road adhesion conditions under different vehicle speeds.
[0085] The specific simulation scenario settings are shown in Table 1:
[0086] Table 1 Simulation Scene Settings
[0087]
[0088] Based on the vehicle's longitudinal velocity, yaw rate, and lateral acceleration, the vehicle stability index (Cost) is calculated under different vehicle speeds and road adhesion conditions (i.e., road adhesion coefficient). s Vehicle nonlinear index Cost nl Vehicle safety comprehensive evaluation index Cost cs The specific calculation method is as described above and will not be repeated here.
[0089] The overall vehicle safety evaluation results are shown in Table 2:
[0090] Table 2 Comprehensive evaluation indicators of vehicle safety under different simulation scenarios
[0091]
[0092] As shown in the simulation results in Table 2, as the road adhesion coefficient (road adhesion condition) decreases, the vehicle safety comprehensive evaluation index gradually changes from negative to positive, the vehicle stability decreases, and the vehicle nonlinearity increases. At this time, reducing the vehicle speed is a relatively effective safety measure. When the road adhesion coefficient is 0.2, reducing the vehicle speed to 40km / h can alleviate the vehicle instability trend to a certain extent, and the vehicle safety comprehensive evaluation index returns to a negative value.
[0093] The vehicle safety comprehensive evaluation method proposed in this invention can not only effectively assess the performance differences of vehicles in linear and nonlinear regions, but also quantitatively distinguish the performance differences of vehicles under different test conditions, and has a certain degree of robustness to test vehicle speed and road adhesion conditions. This evaluation method is expected to enrich the content of vehicle handling stability evaluation, empower autonomous driving decision-making and control algorithms, and provide a theoretical basis for planning corresponding safety measures under different operating conditions.
[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.
Claims
1. A comprehensive vehicle safety evaluation method, characterized in that, Includes the following steps: Based on the actual vehicle state and the vehicle state safety boundary value, the vehicle stability index, which characterizes the degree of vehicle stability, is calculated. Based on the actual vehicle state and the expected driving state, calculate the vehicle nonlinearity index, which characterizes the degree of vehicle nonlinearity. Based on the vehicle stability index and the vehicle nonlinearity index, a comprehensive vehicle safety evaluation index is constructed to characterize the overall safety characteristics of the vehicle. The vehicle state safety boundary value is determined by the yaw rate safety boundary value. Lateral acceleration safety boundary value Characterization; The vehicle stability index is calculated using the following formula: ， The expected driving state is determined by the expected yaw rate. Expected lateral acceleration Characterization; The vehicle nonlinearity index is calculated by the following formula: 。 2. The vehicle safety comprehensive evaluation method according to claim 1, characterized in that, The expression for the comprehensive vehicle safety evaluation index is as follows: in, For vehicle safety comprehensive evaluation indicators, To stabilize index weights, For vehicle stability index, Non-linear exponential weights 、 This is the nonlinear index of the vehicle.
3. The vehicle safety comprehensive evaluation method according to claim 2, characterized in that, The actual state of the vehicle is determined by its actual yaw rate. Actual lateral acceleration Characterization.
4. The vehicle safety comprehensive evaluation method according to claim 1, characterized in that: The yaw rate safety boundary value Lateral acceleration safety boundary value Calculated by the following formula, in, For the longitudinal speed of the vehicle, Let g be the road adhesion coefficient and g be the acceleration of the center of gravity.
5. The vehicle safety comprehensive evaluation method according to claim 2, characterized in that, The stability index weight and nonlinear index weight are adaptively adjusted based on the vehicle state safety boundary value, the actual vehicle state, and the expected driving state.
6. The vehicle safety comprehensive evaluation method according to claim 5, characterized in that, The adaptive adjustment method is as follows: The area of the rectangle enclosed by the vehicle's safety boundary values is denoted as . S ; Let the area of the rectangle enclosed by the actual state of the vehicle be denoted as . ; The area of the rectangle enclosed by the deviation between the actual vehicle state and the expected driving state is denoted as . ; Let the initial value of the stability index weight be denoted as . The initial value of the nonlinear exponential weight is denoted as ; The weights of the stable exponent and the nonlinear exponent are normalized: 。 7. The vehicle safety comprehensive evaluation method according to claim 1, characterized in that, The actual state of the vehicle is sensed by sensors, and the expected driving state is generated by driving data calibration or the vehicle stability control system.
8. A comprehensive vehicle safety evaluation system, characterized in that, include: The vehicle stability index calculation module is configured to calculate the vehicle stability index, which characterizes the degree of vehicle stability, based on the actual vehicle state and the vehicle state safety boundary value. The vehicle nonlinear index calculation module is configured to calculate the vehicle nonlinear index, which characterizes the degree of vehicle nonlinearity, based on the actual state of the vehicle and the expected driving state. The vehicle safety comprehensive evaluation index construction module is configured to construct a vehicle safety comprehensive evaluation index characterizing the overall safety characteristics of a vehicle based on the vehicle stability index and the vehicle nonlinearity index. The vehicle state safety boundary value is determined by the yaw rate safety boundary value. Lateral acceleration safety boundary value Characterization; The vehicle stability index is calculated using the following formula: ， The expected driving state is determined by the expected yaw rate. Expected lateral acceleration Characterization; The vehicle nonlinearity index is calculated by the following formula: 。