A roll-over evaluation method considering a vehicle roll-over danger tendency
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SICHUAN UNIVERSITY OF SCIENCE AND ENGINEERING
- Filing Date
- 2026-03-20
- Publication Date
- 2026-06-19
Smart Images
Figure CN122232640A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of vehicle driving safety technology, and in particular to a rollover evaluation method that takes into account the risk of vehicle rollover. Background Technology
[0002] With the rapid development of the automotive industry, vehicle rollover accidents have become a significant threat to road safety. Existing vehicle rollover warning and control systems are core technologies for improving active vehicle safety, and their effectiveness highly depends on the accuracy and reliability of rollover evaluation indicators. Currently, the academic community has proposed various rollover evaluation indicators and warning methods, but in practical applications, they still exhibit certain time lags and low warning accuracy, preventing active rollover mitigation control systems from controlling the vehicle in a timely manner. Existing technologies, targeting multi-axle special vehicles, optimize the calculation accuracy of the rollover index (LTR) through refined dynamic models and attempt to establish adaptive warning thresholds related to vehicle speed and road friction coefficients. The limitations of this method are: first, its model is highly dependent on specific vehicle parameters and a large amount of offline simulation data for calibration, resulting in poor algorithm portability and versatility; second, the complex model calculations place high demands on the computing power of the onboard processor, affecting the response speed of real-time warnings; third, it can only characterize the current vehicle state and cannot provide warnings for future moments, leading to time lags in vehicle warnings and failing to better guarantee the stability and safety of vehicle operation. Furthermore, existing technologies attempt to construct comprehensive risk assessment coefficients by integrating multi-source information such as vehicle status, road conditions, and environmental safety. However, this method faces challenges in engineering implementation: on the one hand, some parameters in its indicator system (such as real-time road surface smoothness and tire temperature) are difficult to obtain reliably and economically in real-world vehicle environments; on the other hand, the large computational model and the reliance on empirically preset static risk thresholds make it difficult for the system to achieve rapid and accurate risk assessment in dynamically changing and complex coupled scenarios.
[0003] In summary, current rollover assessment metrics generally suffer from poor vehicle compatibility, insufficient consideration of system dynamic coupling, and a difficulty in balancing computational complexity and real-time performance. Therefore, there is an urgent need for a more universal, computationally efficient rollover assessment metric and early warning method that can predict future hazard trends and the current level of danger for vehicles, while integrating multi-source real-time information. This would improve the accuracy of rollover warnings for various vehicles under complex conditions and ensure vehicle safety. Summary of the Invention
[0004] In view of the above-mentioned shortcomings in the prior art, the rollover evaluation method that considers the rollover risk trend of the vehicle provided in this application solves the problem that the existing indicators do not take into account the rollover risk trend of the vehicle at the current moment, making it difficult to guarantee the vehicle's driving stability and safety, and realizes a fundamental shift from early warning to trend intervention.
[0005] To achieve the aforementioned objectives, the technical solution adopted in this application is as follows: This application provides a rollover assessment method that considers the tendency of vehicle rollover hazards, including: S1: Construct nonlinear state equations and linear observation equations, and use the extended Kalman filter algorithm to estimate the vehicle's center of gravity height at the current moment; S2: Based on the current height of the vehicle's center of gravity, calculate the vehicle's total mechanical energy at the current moment according to the law of conservation of energy; S3: Calculate the minimum potential energy required for the critical state of vehicle rollover based on the triangle relationship; S4: Calculate the vehicle's input power at the current moment; S5: Based on the total mechanical energy, the minimum potential energy required for the critical state of vehicle rollover, and the input power, calculate the comprehensive vehicle rollover evaluation index, and determine whether the vehicle currently has a risk of rollover based on the comprehensive vehicle rollover evaluation index.
[0006] The beneficial effects of the above scheme are: considering the dynamic process of vehicle rollover from an energy perspective, by calculating the ratio of the vehicle's total mechanical energy to its minimum potential energy at the current moment, and combining this with the rate of change of the vehicle's rollover energy at the current moment, it not only meets the basic rollover judgment requirements, but also enables the judgment of the vehicle's current dangerous trend, improves the stability of vehicle driving, and solves the problems of inaccurate warning timing and delayed response of general rollover evaluation indicators for the current vehicle status.
[0007] Further, S1 includes: S101: Construct and discretize a dedicated model based on vehicle longitudinal dynamics and for estimating the vehicle's center of gravity height. The expression is as follows:
[0008]
[0009]
[0010]
[0011]
[0012]
[0013] in, For the total mass of the vehicle. For longitudinal velocity, superscript For the derivative with respect to time, and For the longitudinal force of the front and rear wheels, For air resistance, It is the acceleration due to gravity. The longitudinal slope of the road. For the moment of inertia of the wheel, and The angular velocities of the front and rear wheels are... and For the torque of the front and rear wheels, and The rolling resistance torque of the front and rear wheels, The equivalent radius of the wheel. for The longitudinal speed of the vehicle at any given time, for The longitudinal speed of the vehicle at any given time, Sampling time, for The angular velocity of the front wheel at any given moment, for The angular velocity of the front wheel at any given moment, for The angular velocity of the rear wheel at that moment, for The angular velocity of the rear wheel at that moment; S102: Calculate the longitudinal forces on the front and rear wheels of the vehicle. The calculation formula is as follows:
[0014]
[0015] in, This is the proportionality coefficient; S103: Calculate air resistance and, based on the longitudinal forces of the front and rear wheels, calculate the rolling resistance torque of the front and rear wheels. The calculation formula is as follows:
[0016]
[0017] in, The air drag coefficient, The rolling resistance torque of the front and rear wheels, This is the tire rolling resistance coefficient. The vertical forces acting on the front and rear tires of the vehicle. For the front and rear tires, For the rear tires, For the front tires; S104: When a road longitudinal slope exists, calculate the corresponding vertical forces on the front and rear tires using the following formula:
[0018]
[0019] in, The vertical force is that of the front tire. The vertical force on the rear tire. Let be the acceleration of the vehicle along its vertical motion. For longitudinal acceleration, This is the derivative of the road's longitudinal slope. Wheelbase This refers to the front wheelbase. Rear wheelbase For equivalent acceleration, The height of the vehicle's center of gravity; S105: Select state variables Input quantity Construct the nonlinear state equation and the linear observation equation, expressed as follows:
[0020]
[0021] in, For nonlinear state equations, superscript For transpose, , , and As an intermediate variable, For linear observation equations, For process noise, It is a coefficient matrix; S106: Based on the nonlinear state equation and the linear observation equation, the extended Kalman filter algorithm is used to estimate the vehicle's center of gravity height in real time, thus obtaining the vehicle's center of gravity height at the current moment.
[0022] Furthermore, the real-time estimation of the vehicle's center of gravity height based on the nonlinear state equation and the linear observation equation, using the extended Kalman filter algorithm, yields the vehicle's center of gravity height at the current moment, including: A1: The nonlinear state equation is discretized using the first-order Euler method, and the calculation formula is as follows:
[0023] in, for The status of the system at all times. for The status of the system at all times. for Input to the time system; A2: Calculate the Jacobian matrix based on the discretized nonlinear state equations. The calculation formula is as follows:
[0024]
[0025]
[0026]
[0027]
[0028]
[0029] in, For Jacobian matrices, for The predicted value of the time system, It is the identity matrix; A3: Set the initial state estimate and initial covariance matrix estimate, and perform nonlinear state prediction. Calculate the Jacobian matrix and prediction covariance of the state transition. The calculation formula is as follows:
[0030]
[0031] in, In order to be in Time system The state at any given moment, In order to be in The status of the system at all times. In order to be in Time system Covariance at time, In order to be in Covariance of the time system The process noise covariance matrix; A4: Calculate the Kalman gain based on the predicted covariance, and update the state estimate and covariance matrix estimate based on the Kalman gain. The calculation formula is as follows:
[0032]
[0033]
[0034] in, For Kalman gain, To observe the noise covariance matrix, for The optimal state estimate of the system at time 10:00. for Covariance of the time-series system; A5: Based on the predicted state, the covariance matrix of the predicted state, and the Kalman gain, a posterior estimation is performed to obtain the vehicle's center of gravity height at the current moment.
[0035] The beneficial effects of the above scheme are: since the center of gravity height is difficult to obtain from actual sensors, the above calculation can estimate the center of gravity height of the vehicle at the current moment, making it easier to deploy in different vehicle systems and provide data support for the calculation of the comprehensive evaluation index of vehicle rollover.
[0036] Further, S2 includes: S201: Calculate the roll kinetic energy of the vehicle in its current state. The calculation formula is as follows:
[0037] in, This is the vehicle's lateral kinetic energy. Let be the moment of inertia of the vehicle about its roll axis. This refers to the roll angular velocity; S202: Based on the current vehicle center of gravity height, calculate the change in vehicle center of gravity height with roll angle. The calculation formula is as follows:
[0038] in, This represents the change in the vehicle's center of gravity height. The wheelbase is the distance between the wheels. The height of the vehicle's center of gravity. The roll angle; S203: Based on the change in vehicle center of gravity height with roll angle, calculate the potential energy difference between the vehicle's current state and its horizontal state. The calculation formula is as follows:
[0039] in, This represents the potential energy difference relative to the horizontal state. S204: Based on the vehicle's current roll kinetic energy and the potential energy difference relative to the horizontal state, calculate the total mechanical energy related to rollover within the vehicle at the current moment according to the law of conservation of energy. The calculation formula is as follows:
[0040] in, The total mechanical energy associated with the rollover.
[0041] The beneficial effects of the above scheme are: by calculating the total mechanical energy of the vehicle at the current moment, the computational complexity is greatly reduced, making it easier to deploy in different vehicle systems and providing data support for the calculation of comprehensive evaluation indicators for vehicle rollover.
[0042] Further, S3 includes: S301: Based on the triangle relationship, calculate the distance from the vehicle's center of gravity height to the extreme rollover position. The calculation formula is:
[0043] in, This is the distance from the vehicle's center of gravity to its maximum rollover point. S302: Based on the distance from the vehicle's center of gravity to the extreme rollover position, calculate the minimum potential energy required for the vehicle to reach the critical rollover state using the potential energy calculation formula. The calculation formula is as follows:
[0044] in, The minimum potential energy required for the critical state of a vehicle rollover.
[0045] The beneficial effect of the above scheme is that, through the above calculation, the minimum potential energy required for vehicle rollover is obtained, which is used to calculate the comprehensive evaluation index of vehicle rollover.
[0046] Further, S4 includes: The formula for calculating the power of the lateral inertial force of the vehicle at the current moment is:
[0047] in, The power of work done by the lateral inertial force. This represents the vehicle's lateral acceleration at the current moment. The formula for calculating the damping power consumption of the vehicle at the current moment is:
[0048] in, To dampen the power consumption, It is the vehicle's equivalent roll damping and is always negative.
[0049] The beneficial effect of the above scheme is that, through the above calculation, the energy margin of the vehicle at the current moment can be obtained, which can be used to judge the rollover risk trend of the vehicle at the current moment.
[0050] Further, S5 includes: S501: Calculate the ratio of the total mechanical energy related to rollover within the vehicle at the current moment to the minimum potential energy required for the vehicle to reach the critical rollover state, thus obtaining the first rollover evaluation index. The calculation formula is as follows:
[0051] in, The primary evaluation criterion for rollover; S502: Calculate the difference between the power done by the lateral inertial force and the power consumed by the damping to obtain the second rollover evaluation index. The calculation formula is as follows:
[0052] in, The second evaluation indicator for rollover is... For a specific moment; S503: Introduces the estimated time for a vehicle to reach the rollover critical state from its current state. The calculation formula is:
[0053] S504: Based on the estimated time for the vehicle to reach the rollover critical state from its current state, the second rollover evaluation index is normalized to obtain the third rollover evaluation index. The calculation formula is as follows:
[0054] in, This is the third evaluation indicator for rollover. S505: Based on the first and third rollover evaluation indicators, a comprehensive vehicle rollover evaluation indicator is obtained, calculated using the following formula:
[0055] in, For comprehensive vehicle rollover evaluation indicators; S506: Based on the vehicle's actual maximum permissible energy and critical energy, calculate the three-level safety threshold using the following formula:
[0056] in, The threshold is level three. The maximum energy that is actually allowed. The critical energy. For safety indicators, For safety factor; S507: Based on comprehensive vehicle rollover evaluation indicators and three-level safety thresholds, determine whether the current vehicle has a risk of rollover.
[0057] The beneficial effects of the above scheme are: through the above calculation, a comprehensive rollover evaluation index and a three-level safety threshold for the current state of the vehicle are obtained, which are used to judge the rollover risk level and risk trend of the vehicle at the current moment, and significantly improve the vehicle's driving stability and safety.
[0058] Furthermore, the determination of whether a vehicle currently exhibits a rollover risk trend based on comprehensive vehicle rollover evaluation indicators and three-level safety thresholds includes: If the comprehensive vehicle rollover evaluation index is greater than the first-level safety threshold, it indicates that the vehicle has entered the risk concern zone, and the indicator light will flash to remind the driver. If the comprehensive vehicle rollover evaluation index is greater than the level 2 safety threshold, it indicates that the vehicle has entered a risk and danger zone, and proactive warnings will be issued to remind the driver to intervene. If the comprehensive vehicle rollover evaluation index is greater than the level three safety threshold, it indicates that the vehicle has entered a risk emergency zone and rollover control measures should be taken.
[0059] The beneficial effect of the above scheme is that the three-level response threshold fully reflects the ability of the rollover evaluation index to reflect the degree of danger and trend.
[0060] Furthermore, the rollover assessment method considering the tendency of vehicle rollover hazards also includes: Use the first or second rollover evaluation index to determine whether the vehicle is at risk of rollover.
[0061] Furthermore, the step of using the first rollover evaluation index or the second rollover evaluation index to determine whether the current vehicle has a rollover risk trend includes: If the second rollover evaluation index is greater than the preset rollover threshold, it indicates that the current vehicle rollover risk trend is on the rise. If the first evaluation index is greater than the preset stability coefficient, and the second evaluation index is greater than zero, it indicates that the vehicle is at risk of rolling over.
[0062] The beneficial effect of the above scheme is that by not merging the two indicators into a single indicator, but treating them as two independent judgment dimensions, a two-dimensional decision plane is constructed, which improves the response speed and thus achieves more refined early warning.
[0063] The beneficial effects of this application are: This application provides a rollover assessment method that considers the risk trend of vehicle rollover. The design emphasizes lightweight algorithms and information accessibility. The index is constructed based on core vehicle motion state parameters that are easy to measure in real time, without relying on parameters that are difficult to obtain in real time, such as the road adhesion coefficient. While ensuring high early warning accuracy, it significantly reduces computational complexity, making it easier to deploy and implement in vehicle systems on different computing platforms. Furthermore, it achieves a leap from static instantaneous evaluation indicators to dynamic trend prediction, solving the problems of inaccurate early warning timing and delayed response in existing technologies. It provides a more accurate characterization of dynamic coupling characteristics, enhances the perception and assessment capabilities under complex coupled hazardous conditions, and improves the stability and safety of vehicles during operation. Attached Figure Description
[0064] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.
[0065] Figure 1 This is a flowchart illustrating a rollover assessment method that considers the risk of vehicle rollover, as provided in an embodiment of this application.
[0066] Figure 2 This is a schematic diagram of a three-degree-of-freedom vehicle model for center of gravity height estimation, provided as an embodiment of this application.
[0067] Figure 3 This is a schematic diagram illustrating the change in center of gravity height distance, provided as an embodiment of this application.
[0068] Figure 4 This is a schematic diagram of vehicle tilting provided in an embodiment of this application.
[0069] Figure 5 A method based on the embodiments of this application is provided. A two-dimensional mapping diagram. Detailed Implementation
[0070] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.
[0071] Example 1: This application provides a rollover evaluation method considering the risk of vehicle rollover. This method can be applied to a vehicle rollover warning controller, which acquires data signals through joint simulation using Trucksim and Simulink. Taking a specific vehicle model (parameters shown in Table 1) under double lane change conditions as an example, the calculation process and application results of this index are illustrated. The method can be found in [reference needed]. Figure 1 , Figure 1 The diagram shown is a flowchart illustrating a rollover assessment method considering the tendency of vehicle rollover risk, as provided in an embodiment of this application, including: S1: Construct nonlinear state equations and linear observation equations, and use the extended Kalman filter algorithm to estimate the vehicle's center of gravity height at the current moment.
[0072] Furthermore, S1 includes: S101: Build a dedicated model based on vehicle longitudinal dynamics for estimating the vehicle's center of gravity height and discretize it (longitudinal, front wheel rotation, rear wheel rotation). Figure 2 As shown: Vertical:
[0073] Discretization:
[0074] Front wheel:
[0075] Discretization:
[0076] rear wheel:
[0077] Discretization:
[0078] in, For the total mass of the vehicle. For longitudinal velocity, superscript For the derivative with respect to time, and For the longitudinal force of the front and rear wheels, For air resistance, It is the acceleration due to gravity. The longitudinal slope of the road. For the moment of inertia of the wheel, and The angular velocities of the front and rear wheels are... and For the torque of the front and rear wheels, and The rolling resistance torque of the front and rear wheels, The equivalent radius of the wheel. for The longitudinal speed of the vehicle at any given time, for The longitudinal speed of the vehicle at any given time, Sampling time, for The angular velocity of the front wheel at any given moment, for The angular velocity of the front wheel at any given moment, for The angular velocity of the rear wheel at that moment, for The angular velocity of the rear wheel at that moment.
[0079] S102: Calculate the linear tire model:
[0080]
[0081] in, This is a proportionality coefficient; under a small slip ratio, the longitudinal force of the tire is linearly related to the slip ratio.
[0082] S103: Calculate air resistance and, based on the longitudinal forces of the front and rear wheels, calculate the rolling resistance torque of the front and rear wheels. The calculation formula is as follows:
[0083]
[0084] in, The air drag coefficient, The rolling resistance torque of the front and rear wheels, This is the tire rolling resistance coefficient. The vertical forces acting on the front and rear tires of the vehicle. For the front and rear tires, For the rear tires, For the front tires.
[0085] S104: When a road longitudinal slope exists, calculate the corresponding vertical forces on the front and rear tires using the following formula:
[0086]
[0087] in, The vertical force is that of the front tire. The vertical force on the rear tire. Let be the acceleration of the vehicle along its vertical motion. For longitudinal acceleration, This is the derivative of the road's longitudinal slope. Wheelbase This refers to the front wheelbase. Rear wheelbase For equivalent acceleration, This refers to the height of the vehicle's center of gravity.
[0088] S105: Select state variables Input quantity We construct a nonlinear state equation and a linear observation equation based on the system's observations, resulting in the following expression:
[0089]
[0090] in, For nonlinear state equations, superscript For transpose, , , and As an intermediate variable, For linear observation equations, For process noise, It is a coefficient matrix.
[0091] S106: Optimize the results using the extended Kalman filter algorithm.
[0092] The optimization process includes: A1: The nonlinear state equation is discretized using the first-order Euler method, and the calculation formula is as follows:
[0093] in, for The status of the system at all times. for The status of the system at all times. for Input to the time system; A2: Calculate the Jacobian matrix based on the discretized nonlinear state equations. The calculation formula is as follows:
[0094]
[0095] Among them, the longitudinal velocity equation is: The equation for the angular velocity of the front wheel is: Rear wheel angular velocity equation: Equation for center of gravity height: To simplify the model and ensure filtering stability, it is assumed that the centroid height remains constant during the current sampling period.
[0096] Calculation of partial derivatives of tire force:
[0097] in, For Jacobian matrices, for The predicted value of the time system, It is the identity matrix; A3: Initialize the initial state estimate and the initial covariance matrix estimate: ; in, The initial state estimate of the system. As the initial value, Let be the covariance matrix of the system at the initial time. The initial covariance; A4: Perform nonlinear state prediction, calculate the Jacobian matrix of the state transition and the prediction covariance, using the following formula:
[0098]
[0099] in, In order to be in Time system The state at any given moment, In order to be in The status of the system at all times. In order to be in Time system Covariance at time, In order to be in Covariance of the time system The process noise covariance matrix; A5: Calculate the Kalman gain based on the predicted covariance, and update the state estimate and covariance matrix estimate based on the Kalman gain. The calculation formula is as follows:
[0100]
[0101]
[0102] in, For Kalman gain, To observe the noise covariance matrix, for The optimal state estimate of the system at time 10:00. for Covariance of the time-series system; A6: Based on the predicted state, the covariance matrix of the predicted state, and the Kalman gain, a posterior estimation is performed to obtain the vehicle's center of gravity height at the current moment.
[0103] Since the center of gravity height is difficult to obtain from actual sensors, the above calculations estimate the vehicle's current center of gravity height, making it easier to deploy in different vehicle systems and providing data support for the calculation of comprehensive vehicle rollover evaluation indicators.
[0104] S2: Calculate the total mechanical energy of the vehicle at the current moment based on the law of conservation of energy.
[0105] Furthermore, S2 includes: S201: Calculate the roll kinetic energy of the vehicle in its current state. The calculation formula is as follows:
[0106] in, This is the vehicle's lateral kinetic energy. Let be the moment of inertia of the vehicle about its roll axis. This refers to the roll angular velocity; S202: Calculate the change in vehicle center of gravity height with roll angle. The calculation formula is:
[0107] in, This represents the change in the vehicle's center of gravity height. The wheelbase is the distance between the wheels. The height of the vehicle's center of gravity. The roll angle; S203: Based on the change in vehicle center of gravity height with roll angle, calculate the potential energy difference between the vehicle's current state and its horizontal state. The calculation formula is as follows:
[0108] in, The potential energy difference is relative to the horizontal state. For the total mass of the vehicle. It is the acceleration due to gravity; S204: Based on the vehicle's current roll kinetic energy and the potential energy difference relative to the horizontal state, calculate the total mechanical energy related to rollover within the vehicle at the current moment according to the law of conservation of energy. The calculation formula is as follows:
[0109] in, The total mechanical energy associated with the rollover.
[0110] Table 1 Vehicle Parameters
[0111] Assuming a certain simulation time t The real-time state parameters obtained by the sensor measurement are shown in Table 2.
[0112] Table 2 Real-time Status Parameters
[0113] Substituting the data, we calculate: ; ; ; .
[0114] S3: Calculate the minimum potential energy required for the critical state of vehicle rollover based on the triangle relationship.
[0115] Furthermore, S3 specifically includes: S301: Based on the triangle relationship, such as Figure 3 As shown, the distance from the vehicle's center of gravity height to the extreme rollover position is calculated using the following formula:
[0116] in, This is the distance from the vehicle's center of gravity to its maximum rollover point. S302: Based on the distance from the vehicle's center of gravity to the extreme rollover position, calculate the minimum potential energy required for the vehicle to reach the critical rollover state using the potential energy calculation formula. The calculation formula is as follows:
[0117] in, The minimum potential energy required for the critical state of a vehicle rollover.
[0118] Substituting the data, we calculate: ; .
[0119] S4: Calculate the vehicle's input power at the current moment.
[0120] Furthermore, S4 specifically includes: like Figure 4 As shown, where, This is the vehicle's equivalent roll stiffness. and The vertical loads for the left and right wheels are respectively. For the sprung mass of the vehicle, Let the vehicle body roll angle be the current moment. Calculate the power output of the lateral inertial force on the vehicle at that moment using the following formula:
[0121] in, The power of work done by the lateral inertial force. This represents the vehicle's lateral acceleration at the current moment. The formula for calculating the damping power consumption of the vehicle at the current moment is:
[0122] in, To dampen the power consumption, It is the vehicle's equivalent roll damping and is always negative.
[0123] Substituting the data, we calculate: ; .
[0124] S5: Based on the total mechanical energy, the minimum potential energy required for the critical state of vehicle rollover, and the input power, calculate the comprehensive vehicle rollover evaluation index, and determine whether the vehicle currently has a risk of rollover based on the comprehensive vehicle rollover evaluation index.
[0125] Furthermore, S5 specifically includes: S501: Calculate the ratio of the total mechanical energy related to rollover within the vehicle at the current moment to the minimum potential energy required for the vehicle to reach the critical rollover state, thus obtaining the first rollover evaluation index. The calculation formula is as follows:
[0126] in, The primary evaluation criterion for rollover; S502: Calculate the difference between the power done by the lateral inertial force and the power consumed by the damping to obtain the second rollover evaluation index. The calculation formula is as follows:
[0127] in, The second evaluation indicator for rollover is... For a specific moment; S503: Based on the first and second rollover evaluation indicators, a comprehensive vehicle rollover evaluation indicator is obtained. The calculation formula is as follows:
[0128] in, For comprehensive vehicle rollover evaluation indicators; S504: To fully leverage the indicators' ability to reflect the degree and trend of danger, a three-level safety response threshold is set, calculated using the following formula:
[0129] in, The threshold is level three. The maximum energy that is actually allowed. The critical energy. For safety indicators, For safety factor; S504: Based on the comprehensive vehicle rollover evaluation index and the three-level safety threshold, determine whether the current vehicle has a risk of rollover.
[0130] Substituting the data, we calculate: ; .
[0131] In one embodiment of this application, a characteristic time constant is introduced into the second rollover evaluation index to unify the dimensions. Its physical meaning is the estimated time for the vehicle to reach the rollover critical state from its current state. In this example, we take... seconds (this value is obtained based on the dynamic characteristics calibration of the target vehicle model) The energy change rate index is normalized to obtain the third rollover evaluation index, and the calculation formula is as follows:
[0132] in, As the third evaluation indicator for rollover, substituting the data yields: Finally, the comprehensive rollover evaluation index is calculated. Take the weighting coefficient , (The percentages representing the emphasis on the current state or the current trend are respectively) Substituted into the calculation to obtain .
[0133] Threshold determination method: The regulations require vehicles to not roll over under a lateral acceleration of 0.8g; calculate the corresponding safety indicators. If we take a safety factor of 0.8, then the secondary safety threshold is... .
[0134] The actual maximum allowable energy and critical energy of the vehicle determine the magnitude of the safety index. If the comprehensive vehicle rollover evaluation index is greater than the first-level safety threshold of 0.25, it indicates that the vehicle has entered the risk concern zone, and the indicator light flashes to remind the driver. If the comprehensive vehicle rollover evaluation index is greater than the second-level safety threshold of 0.50, it indicates that the vehicle has entered the risk danger zone, and an active warning is issued to remind the driver to intervene. If the comprehensive vehicle rollover evaluation index is greater than the third-level safety threshold of 0.70, it indicates that the vehicle has entered the risk emergency zone, and the system intervenes to take rollover control measures.
[0135] In one embodiment of this application, instead of merging the two indicators into a single indicator, they are treated as two independent judgment dimensions to construct a two-dimensional decision plane, thereby achieving more refined early warning. Energy state and energy change rate thresholds are set separately. Specific values are calibrated through real-vehicle tests, with the average value measured during steady-state steering of the vehicle at 0.3-0.5g used as the baseline. (Based on experimental calibration, representing a significant dangerous energy input rate.) Within the region defined in the decision-making plane, implement corresponding early warning and control strategies. Within the plane, the following threshold lines are set to divide the area into four warning zones, such as... Figure 5 As shown, ① represents the safe zone: No driver intervention is required; ② Indicates a warning zone: ① To remind the driver to pay attention; ② To indicate a danger zone: ④ Indicates the emergency zone: (This is a reminder for the driver to intervene.) Active anti-rollover control measures are implemented.
[0136] If the second rollover evaluation index is greater than the preset rollover threshold, it indicates that the current vehicle rollover risk is on the rise; if the first rollover evaluation index is greater than the preset stability coefficient, and if the second rollover evaluation index is greater than zero, it indicates that the current vehicle has a rollover risk trend. During normal driving, minor road imperfections or slight driver corrections will produce positive [various effects / significance]. However, these usually do not pose a rollover hazard, and the rates of change of +500W and +5000W represent completely different levels of danger approach. Setting a threshold can distinguish between "slight accumulation" and "rapid deterioration", filtering out noise, reducing false alarm rate, and achieving a more refined response.
[0137] To verify the effectiveness of the index described in this embodiment, it was compared with the traditional Static Stability Factor (SSF) and Dynamic Rollover Threshold (LTR) under the same double lane change condition in simulation. The comprehensive index of this invention, by setting a reasonable threshold, can determine the degree of danger of a vehicle in its current state. More importantly, this index... This clearly indicates that the total mechanical energy of the system is increasing rapidly, and the risk of vehicle rollover is on the rise—key information that general rollover indicators cannot provide. Experimental results show that, using the indicators proposed in this application, the system can... Early warnings are issued in advance, while general indicators, under the same conditions, remain unchanged until... The warning was triggered, which verifies the ability of the indicators in this application to predict dangerous trends.
[0138] This application provides a rollover assessment method that considers the risk trend of vehicle rollover. The design emphasizes lightweight algorithms and information accessibility. The index is constructed based on core vehicle motion state parameters that are easy to measure in real time, without relying on parameters that are difficult to obtain in real time, such as the road adhesion coefficient. While ensuring high early warning accuracy, it significantly reduces computational complexity, making it easier to deploy and implement in vehicle systems on different computing platforms. Furthermore, it achieves a leap from static instantaneous evaluation indicators to dynamic trend prediction, solving the problems of inaccurate early warning timing and delayed response in existing technologies. It provides a more accurate characterization of dynamic coupling characteristics, enhances the perception and assessment capabilities under complex coupled hazardous conditions, and improves the stability and safety of vehicles during operation.
[0139] It should be noted that those skilled in the art will recognize that the embodiments described herein are for the purpose of helping readers understand the principles of this application, and should be understood as not limiting the scope of protection of this application to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this application without departing from the essence of this application, and these modifications and combinations are still within the scope of protection of this application.
Claims
1. A rollover assessment method considering the tendency of vehicle rollover hazards, characterized in that, include: S1: Construct nonlinear state equations and linear observation equations, and use the extended Kalman filter algorithm to estimate the vehicle's center of gravity height at the current moment; S2: Based on the current height of the vehicle's center of gravity, calculate the vehicle's total mechanical energy at the current moment according to the law of conservation of energy; S3: Calculate the minimum potential energy required for the critical state of vehicle rollover based on the triangle relationship; S4: Calculate the vehicle's input power at the current moment; S5: Based on the total mechanical energy, the minimum potential energy required for the critical state of vehicle rollover, and the input power, calculate the comprehensive vehicle rollover evaluation index, and determine whether the vehicle currently has a risk of rollover based on the comprehensive vehicle rollover evaluation index.
2. The rollover assessment method considering the risk of vehicle rollover as described in claim 1, characterized in that, S1 includes: S101: Construct and discretize a dedicated model based on vehicle longitudinal dynamics and for estimating the vehicle's center of gravity height. The expression is as follows: in, For the total mass of the vehicle. For longitudinal velocity, superscript For the derivative with respect to time, and For the longitudinal force of the front and rear wheels, For air resistance, It is the acceleration due to gravity. The longitudinal slope of the road. For the moment of inertia of the wheel, and The angular velocities of the front and rear wheels are... and For the torque of the front and rear wheels, and The rolling resistance torque of the front and rear wheels, The equivalent radius of the wheel. for The longitudinal speed of the vehicle at any given time, for The longitudinal speed of the vehicle at any given time, Sampling time, for The angular velocity of the front wheel at any given moment, for The angular velocity of the front wheel at any given moment, for The angular velocity of the rear wheel at that moment, for The angular velocity of the rear wheel at that moment; S102: Calculate the longitudinal forces on the front and rear wheels of the vehicle. The calculation formula is as follows: in, This is the proportionality coefficient; S103: Calculate air resistance and, based on the longitudinal forces of the front and rear wheels, calculate the rolling resistance torque of the front and rear wheels. The calculation formula is as follows: in, The air drag coefficient, The rolling resistance torque of the front and rear wheels, This is the tire rolling resistance coefficient. The vertical forces acting on the front and rear tires of the vehicle. For the front and rear tires, For the rear tires, For the front tires; S104: When a road longitudinal slope exists, calculate the corresponding vertical forces on the front and rear tires using the following formula: in, The vertical force is that of the front tire. The vertical force on the rear tire. Let be the acceleration of the vehicle along its vertical motion. For longitudinal acceleration, This is the derivative of the road's longitudinal slope. Wheelbase This refers to the front wheelbase. Rear wheelbase For equivalent acceleration, The height of the vehicle's center of gravity; S105: Select state variables Input quantity Construct the nonlinear state equation and the linear observation equation, expressed as follows: in, For nonlinear state equations, superscript For transpose, , , and As an intermediate variable, For linear observation equations, For process noise, It is a coefficient matrix; S106: Based on the nonlinear state equation and the linear observation equation, the extended Kalman filter algorithm is used to estimate the vehicle's center of gravity height in real time, thus obtaining the vehicle's center of gravity height at the current moment.
3. The rollover assessment method considering the risk of vehicle rollover as described in claim 2, characterized in that, The method, based on nonlinear state equations and linear observation equations, utilizes the extended Kalman filter algorithm to estimate the vehicle's center of gravity height in real time, obtaining the current vehicle center of gravity height, including: A1: The nonlinear state equation is discretized using the first-order Euler method, and the calculation formula is as follows: in, for The status of the system at all times. for The status of the system at all times. for Input to the time system; A2: Calculate the Jacobian matrix based on the discretized nonlinear state equations. The calculation formula is as follows: in, For Jacobian matrices, for The predicted value of the time system, It is the identity matrix; A3: Set the initial state estimate and initial covariance matrix estimate, and perform nonlinear state prediction. Calculate the Jacobian matrix and prediction covariance of the state transition. The calculation formula is as follows: in, In order to be in Time system The state at any given moment, In order to be in The status of the system at all times. In order to be in Time system Covariance at time, In order to be in Covariance of the time system The process noise covariance matrix; A4: Calculate the Kalman gain based on the predicted covariance, and update the state estimate and covariance matrix estimate based on the Kalman gain. The calculation formula is as follows: in, For Kalman gain, To observe the noise covariance matrix, for The optimal state estimate of the system at time 10:
00. for Covariance of the time-series system; A5: Based on the predicted state, the covariance matrix of the predicted state, and the Kalman gain, a posterior estimation is performed to obtain the vehicle's center of gravity height at the current moment.
4. The rollover assessment method considering the risk of vehicle rollover as described in claim 3, characterized in that, S2 includes: S201: Calculate the roll kinetic energy of the vehicle in its current state. The calculation formula is as follows: in, This is the vehicle's lateral kinetic energy. Let be the moment of inertia of the vehicle about its roll axis. This refers to the roll angular velocity; S202: Based on the current vehicle center of gravity height, calculate the change in vehicle center of gravity height with roll angle. The calculation formula is as follows: in, This represents the change in the vehicle's center of gravity height. The wheelbase is the distance between the wheels. The height of the vehicle's center of gravity. The roll angle; S203: Based on the change in vehicle center of gravity height with roll angle, calculate the potential energy difference between the vehicle's current state and its horizontal state. The calculation formula is as follows: in, This represents the potential energy difference relative to the horizontal state. S204: Based on the vehicle's current roll kinetic energy and the potential energy difference relative to the horizontal state, calculate the total mechanical energy related to rollover within the vehicle at the current moment according to the law of conservation of energy. The calculation formula is as follows: in, The total mechanical energy associated with the rollover.
5. The rollover assessment method considering the risk of vehicle rollover as described in claim 4, characterized in that, S3 includes: S301: Based on the triangle relationship, calculate the distance from the vehicle's center of gravity height to the extreme rollover position. The calculation formula is: in, This is the distance from the vehicle's center of gravity to its maximum rollover point. S302: Based on the distance from the vehicle's center of gravity to the extreme rollover position, calculate the minimum potential energy required for the vehicle to reach the critical rollover state using the potential energy calculation formula. The calculation formula is as follows: in, The minimum potential energy required for the critical state of a vehicle rollover.
6. The rollover assessment method considering the risk of vehicle rollover as described in claim 5, characterized in that, S4 includes: The formula for calculating the power of the lateral inertial force of the vehicle at the current moment is: in, The power of work done by the lateral inertial force. This represents the vehicle's lateral acceleration at the current moment. The formula for calculating the damping power consumption of the vehicle at the current moment is: in, To dampen the power consumption, It is the vehicle's equivalent roll damping and is always negative.
7. The rollover assessment method considering the risk of vehicle rollover as described in claim 6, characterized in that, S5 includes: S501: Calculate the ratio of the total mechanical energy related to rollover within the vehicle at the current moment to the minimum potential energy required for the vehicle to reach the critical rollover state, thus obtaining the first rollover evaluation index. The calculation formula is as follows: in, The primary evaluation criterion for rollover; S502: Calculate the difference between the power done by the lateral inertial force and the power consumed by the damping to obtain the second rollover evaluation index. The calculation formula is as follows: in, The second evaluation indicator for rollover is... For a specific moment; S503: Introduces the estimated time for a vehicle to reach the rollover critical state from its current state. The calculation formula is: S504: Based on the estimated time for the vehicle to reach the rollover critical state from its current state, the second rollover evaluation index is normalized to obtain the third rollover evaluation index. The calculation formula is as follows: in, This is the third evaluation indicator for rollover. S505: Based on the first and third rollover evaluation indicators, a comprehensive vehicle rollover evaluation indicator is obtained, calculated using the following formula: in, For comprehensive vehicle rollover evaluation indicators; S506: The Level 3 safety threshold is calculated based on the vehicle's actual maximum permissible energy and critical energy. The calculation formula is as follows: in, The threshold is level three. The maximum energy that is actually allowed. The critical energy. For safety indicators, For safety factor; S507: Based on comprehensive vehicle rollover evaluation indicators and three-level safety thresholds, determine whether the current vehicle has a risk of rollover.
8. The rollover assessment method considering the risk of vehicle rollover as described in claim 7, characterized in that, The determination of whether a vehicle has a rollover risk trend based on comprehensive vehicle rollover evaluation indicators and three-level safety thresholds includes: If the comprehensive vehicle rollover evaluation index is greater than the first-level safety threshold, it indicates that the vehicle has entered the risk concern zone, and the indicator light will flash to remind the driver. If the comprehensive vehicle rollover evaluation index is greater than the level 2 safety threshold, it indicates that the vehicle has entered a risk and danger zone, and proactive warnings will be issued to remind the driver to intervene. If the comprehensive vehicle rollover evaluation index is greater than the level three safety threshold, it indicates that the vehicle has entered a risk emergency zone and rollover control measures should be taken.
9. The rollover assessment method considering the risk of vehicle rollover as described in claim 7, characterized in that, Also includes: Use the first or second rollover evaluation index to determine whether the vehicle is at risk of rollover.
10. The rollover assessment method considering the risk of vehicle rollover as described in claim 9, characterized in that, The method of determining whether a vehicle has a risk of rollover using the first rollover evaluation index or the second rollover evaluation index includes: If the second rollover evaluation index is greater than the preset rollover threshold, it indicates that the current vehicle rollover risk trend is on the rise. If the first evaluation index is greater than the preset stability coefficient, and the second evaluation index is greater than zero, it indicates that the vehicle is at risk of rolling over.