Method for determining asymmetric conditions in a moving vehicle
The diagnostic method addresses vehicle asymmetry by analyzing yaw rates and dynamics to identify and correct unsafe driving conditions, enhancing vehicle safety through real-time detection and differentiation of internal and external causes.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- イージー レイン アイエスピーエー
- Filing Date
- 2024-05-20
- Publication Date
- 2026-06-16
Smart Images
Figure 2026519507000001_ABST
Abstract
Description
[Technical Field]
[0001] This invention relates to a diagnostic method and system for automobiles. Specifically, the invention was developed in relation to the diagnosis of the driving dynamics of automobiles. [Background technology]
[0002] In the dynamics of vehicle driving, when steering wheel control corresponds to a zero steering angle, a situation can often occur where the vehicle does not move in a straight line. The vehicle often follows a path that involves drift, which may be indeterminately perceptible to the driver and / or passengers of the vehicle. This can be caused by vehicle setup issues, driving on a road that is sloped in the transverse direction, differences in the characteristics of the ground under the right and left wheels, and differences in the condition of the right and left wheels.
[0003] In some cases, the occurrence of such asymmetry does not have an immediate impact on the vehicle's driving safety. In other cases, which can occur with equal frequency and are far more relevant, the asymmetry results in a significant deterioration of the vehicle's driving safety, and therefore requires immediate intervention to determine the cause of the asymmetry and the corrective actions that should be implemented. However, while known technologies provide many examples of methods for reactive or predictive control of vehicle dynamics, there are no available solutions regarding the determination of asymmetry in the vehicle itself, or regarding the determination of the cause and the provision of corrective actions.
[0004] Purpose of the invention The present invention aims to solve the technical problems outlined above. Specifically, the object of the present invention is to provide a method for diagnosing asymmetry in vehicle operation that enables not only the determination of asymmetry but also the determination of the cause of the asymmetry, thereby enabling the provision of corrective intervention. [Overview of the Initiative]
[0005] The object of the invention is achieved by a method having the features described in the following claims, which form an integral part of the technical disclosure provided herein in connection with the invention. [Brief explanation of the drawing]
[0006] Hereinafter, the invention will be described with reference to the attached figures, which are provided merely as non-limiting examples: [Figure 1] A general block diagram of the method according to the invention is shown. [Figure 2] A block diagram of the first step of the method according to the invention is shown. [Figure 3] A block diagram of the second step of the method according to the invention is shown. [Figure 4] A block diagram of the third step of the method according to the invention is shown. [Figure 5] Figure 3 shows the block diagram of the third stage. [Figure 6] Figure 3 shows the block diagram of the third stage. [Figure 7] Figure 3 shows the block diagram of the third stage. [Figure 8] Figure 3 shows the block diagram of the third stage. [Figure 9] A schematic diagram of the dynamics model of an automobile or its parts used in the method according to the invention is shown below. [Figure 10] A schematic diagram of the dynamics model of an automobile or its parts used in the method according to the invention is shown below. [Figure 11] A schematic diagram of the dynamics model of an automobile or its parts used in the method according to the invention is shown below. [Figure 12] A schematic diagram of the dynamics model of an automobile or its parts used in the method according to the invention is shown below. [Figure 13] A schematic diagram of the dynamics model of an automobile or its parts used in the method according to the invention is shown below. [Figure 14]A schematic diagram of the dynamics model of an automobile or its parts used in the method according to the invention is shown below. [Figure 15] A schematic diagram of the dynamics model of an automobile or its parts used in the method according to the invention is shown below. [Modes for carrying out the invention]
[0007] Reference numeral 1 in Figure 1 schematically shows a block diagram of a method for determining asymmetry in the dynamics of an automobile, according to an embodiment of the invention.
[0008] Referring to the complete functional diagram (meaning that various embodiments may assume one or more of the functional blocks shown in Figure 1), the method according to the invention is based on a set of input data 2, a real-time computing stage 4, an intermediate set of output data 6, a (real-time) analysis stage 8, and a final set of output data 10.
[0009] The functional definitions within each stage or set described above may vary according to the computational needs (or resources) and / or the control needs to which the method implements them.
[0010] In embodiments intended to meet more stringent computing and / or control needs, the overall structure is shown in Figure 1, where the real-time computing stage 4 comprises a first computing module 12 configured to operate based on vehicle powertrain data, a second computing module 14 configured to operate based on vehicle overall dynamics data, and a third computing module 16 configured to operate based on individual wheel dynamics data of the vehicle.
[0011] In general, the method of the invention makes it possible to perform two determinations, one of which depends on the other. The essential determination made possible by the method concerns the presence of an asymmetric state that perturbs the vehicle's dynamics. Such a determination may be made based on the yaw rate and consists of determining the vehicle's reference yaw rate (when no perturbation of any kind is present), measuring the vehicle's actual yaw rate, calculating the difference between the reference yaw rate and the actual yaw rate, and reporting the occurrence of an asymmetric state if the difference between the reference yaw rate and the actual yaw rate is greater than a first threshold. This is shown in Figures 2 and 3, and its technical features are described in detail in the following description with reference to Modules 12, 14, and 16.
[0012] Once this determination is made, the method of the invention may, if necessary, perform further determinations regarding the cause of the asymmetry. Such determinations may be more hierarchical than the former and are shown in the diagrams of Figures 4 to 8. Figures 9 to 13 show possible schematic representations of the dynamics model of module 14.
[0013] Vehicle Dynamics: Calculation Module 14 (Overall Dynamics) and Calculation Module 16 (Wheel Dynamics) The dynamics models corresponding to the assemblies of calculation modules 14 and 16 calculate the reference yaw rate of the vehicle (when no perturbation of any kind is present), measure the actual yaw rate of the vehicle, and furthermore, the longitudinal force F that results from the difference between the yaw rates described above. x asim It is used to determine this.
[0014] The objective is to generate a reference signal relating to the velocity of rotation around the vertical axis z in this case. This can later be compared with direct or indirect measurements provided on the vehicle's CAN network (e.g., as the derivative of the yaw rate).
[0015] Therefore, the primary objective is to calculate the forces involved in the rotation of the vehicle. If there is no asymmetry and the drivetrain has an open differential, forces along the longitudinal direction x can be ignored in the calculation of rotational equilibrium. With respect to forces along the transverse direction y, they are calculated by a vehicle dynamics model (which may be a linear model, for example) that can take into account the tire model. The dynamics model encompasses both the determination of the vehicle's transverse and longitudinal dynamics.
[0016] The vehicle dynamics model obtained from the assemblies of modules 14 and 16 is the force Fx transmitted from the wheels to the ground. ij The value can be associated with each rotation angle of the steering wheel and with each vehicle speed value.
[0017] The vehicle's dynamics module uses a set of information items, such as modules 12 and 16, that exist on the CAN network (or on another network of the vehicle), as a set of input data.
[0018] Module 14 consists of five main functions, specifically: - Obtaining data from the CAN network (or another data network in the vehicle) - To handle the transverse dynamics of the vehicle. - Analyzing the development of grip force based on vehicle dynamics. - Analyze the overall contact with the ground. Execute this.
[0019] Module 14 is: - Transverse grip - Longitudinal grip - Sideslip / Yaw Rate It is configured to process data on a CAN network (or on another data network of the vehicle, for example, originating from the vehicle's inertial measurement unit) in order to obtain an estimate of. This is useful for evaluating the overall grip state of the vehicle and for some preliminary evaluations regarding the distribution of forces exchanged at the interface with the ground on the four tires. Such evaluations are independent of the variables considered in the powertrain module 12, and thus, as described above, it should be noted that module 14 can provide different perspectives and different mappings of the vehicle's dynamic state.
[0020] The following list summarizes a set of input data and output data that characterize a preferred embodiment of the dynamics module of vehicle 14. Direct input data - Steering angle δ [°] - Longitudinal acceleration [Number] [m / s 2 - Lateral acceleration [Number] [m / s 2 - Yaw rate r [° / s] or [rad / s]
[0021] Indirect input data - None Required parameters - Vehicle mass m [kg] - Vehicle mass moment of inertia (polar moment of inertia) I z [kg·m 2 - Position of the center of mass of the vehicle (l f and l r , defined by the front wheelbase and the rear wheelbase) - Coefficient of longitudinal aerodynamic resistance C x [-] - Coefficient C of vertical aerodynamic drag z [-] (Generally very small; it can generally affect the calculation of vertical forces acting on the vehicle, and ultimately, it can affect the vertical loads acting on the wheels).
[0022] Output data - Lateral grip [N] - Longitudinal grip [N] - Sideslip angle [°]
[0023] The calculation of mass fluctuations resulting from vehicle use is performed by analyzing wheel torque data and vehicle acceleration data under normal grip conditions. With respect to the polar moment around the z-axis, due to its low sensitivity to fluctuations, it is possible to refer to the provided value without needing to update it during driving. If necessary, the value of the polar moment of inertia around the z-axis can be updated based on the vehicle's mass, which is substantially the only element considered when calculating the moment of inertia that can fluctuate during driving. Specifically, an increase or decrease in mass results in an increase or decrease in the polar moment of inertia, respectively. In this regard, the same considerations provided for updating the vehicle's mass value apply: it can be updated by detecting acceleration during some reference operations (e.g., low-speed operations), or based on the vehicle's overall dynamic equilibrium equations, including fixed and known values (e.g., front and rear wheelbases) and values available on the inertial measurement unit.
[0024] Regarding the lateral dynamics of the vehicle, the preferred theoretical assumption corresponds to the “bicycle” model shown in Figure 10 (of course, other computational models are possible, and therefore the bicycle model should be considered as an example). Theoretical references for calculating the longitudinal dynamics of the vehicle in Module 14 are shown in Figure 11.
[0025] In a preferred embodiment, module 14 has acceleration components along the x-axis (
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[0026] Mass (m), wheelbase (l) of the center of mass f and l r (front wheelbase and rear wheelbase), and the polar moment of inertia of the vehicle from simple equilibrium to lateral translational motion and rotation I z Knowing (the net approximation due to use, as mentioned above), it is possible to determine the following forces by referring to the "bicycle" model in Figure 10, by decomposing the forces on the individual wheels along x and y, and by estimating the distribution of the longitudinal force Fx between the front and rear axles as a function of vertical acceleration or braking force (load transfer).
[0027] Fxf: Longitudinal force on the front axle Fxr: Longitudinal force on the rear axle; Fyf: Transverse force on the front axle Fyr: Transverse force applied to the rear axle.
[0028] Furthermore, by knowing the data on load transfer due to rolling, it is possible to determine the distribution of such forces between the right and left sides (i.e., on individual wheels), and this data is also available on the inertial measurement unit. This is related to reference code Fx ij and Fy ijIt is possible to determine the longitudinal force exchanged between the tire and the vehicle, as shown by the index x or Y, where index x or Y identifies the longitudinal or transverse direction, respectively, where index i identifies the front (1) or rear (2), and index j identifies the left (1) or right (2).
[0029] The determination of forces Fxf, Fxr, Fyf, and Fyr is specifically derived from the following set of dynamic equilibrium equations, which are well known in the prior art. (Overall longitudinal and transverse equilibrium)
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[0030] In the presence of a steering angle δ, the coefficient of grip on the front axle is calculated by decomposing the forces Fyf and Fxf along the steering direction, that is, by recalculating the longitudinal Fxf(δ) and transverse Fyf(δ) components with respect to the center plane of the steering wheel, thereby obtaining the following: Fyf(δ)=Fyf·sen(δ)+Fxf·cos(δ) Fxf(δ)=Fxf·cos(δ)+Fyf·sen(δ) Since the various parameters involved in the dynamic equilibrium equations that can be derived from the diagrams in Figures 10 and 11 can fluctuate during driving, the calculations preferably assume some simplifications. For example, the position of the center of mass can fluctuate during driving, and generally, the values of parameters that affect the vehicle's dynamic equilibrium need to be updated periodically. However, the method of the invention makes it possible to solve the above-mentioned problems of the calculations by providing output data in a discrete configuration, depending on the level of varying magnitudes of the items of output data. Such discretization eliminates the need to know, for example, the exact position of the center of mass of the vehicle in time, or the mass of the vehicle.
[0031] Naturally, if computational effort is not an issue, and if continuous evaluation of output data is possible, it is necessary to update vehicle parameters that may fluctuate during driving according to one or more models available in the literature and currently used in the electronic control of vehicle dynamics.
[0032] To define the average force released to the ground by each tire, it is naturally possible to set a dynamic equilibrium balance that depends solely on the input values from the inertial measurement unit, taking into account the load distribution along the vehicle.
[0033] Module 16 (or "Wheel Module," Figures 12, 13) serves the same purpose as Module 14, iteratively evaluating the grip coefficient of the drive wheels, but performs calculations using other parameters available on the vehicle's data network (CAN or other network) to increase the reliability level in critical conditions.
[0034] On the other hand, the wheel module 17 uses information existing on the CAN network (or another network of the vehicle) as a set of input data, in a manner strictly identical to that of module 12 or module 14.
[0035] Module 16 performs two main operations, specifically: -Retrieve data from the CAN network (or another network on the vehicle), - Calculate slip and frequency analysis on each individual side of the vehicle.
[0036] Therefore, module 16 is configured to process data on the CAN network (or another network in the vehicle) in a manner that obtains instructions for the force in question, which is in dynamic equilibrium, for each wheel.
[0037] To summarize and partially anticipate the following discussion, the following list provides an enumeration of input and output data characterizing a preferred embodiment of the wheel module 16.
[0038] Direct input data Set 1 - Wheel speed (left front wheel, right front wheel, left rear wheel, right rear wheel) [rpm] or [rad / s] - Vehicle forward speed [m / s]
[0039] Set 2 - Wheel speed (left front wheel, right front wheel, left rear wheel, right rear wheel) [rpm] or [rad / s]
[0040] Set 3 - Longitudinal acceleration [m / s²] 2 ] -Transverse acceleration [m / s 2 ]
[0041] Indirect input data -none Required parameters - Wheel rolling radius [m] or [mm]; -Mass moment of inertia of the wheel I zW [kgm 2 ]; Output data Frequency analysis The function of Model 16 is to analyze the vibration frequency of angular velocity ω in order to determine the source of the disorder, specifically whether it is due to a setup problem or to the characteristics of the ground, thereby complementing the mere determination of the presence of an asymmetric state.
[0042] Figure 12 shows a model of the longitudinal dynamics equilibrium of the wheel involved in the calculation process of wheel module 16 based on the data of set 1. With respect to Figure 13, it strictly refers to module 16 for parameters describing the longitudinal dynamics of the vehicle. Values Fy that can be derived from the values of transverse grips Fyf and Fyr. ij Parameters describing transverse dynamics, such as those mentioned above, are primarily used by Module 14.
[0043] More specifically, data (set 2) on the vehicle's CAN network (or another network) is used to determine the value of the longitudinal force released to the ground by all the wheels.
[0044] The dynamic equilibrium equation for wheels is very simple: F x_ij =M eng_ij -M brk_ij -I w_ij ω ij ' Here
[0045] F x_ijThis is the longitudinal force released to the ground by the right / left wheels (i) of the front / rear axle (j). M eng_ij This is the driving torque acting on the right / left wheels (j) of the front / rear axle (i). M brk_ij This is the braking torque acting on the right / left wheels (j) of the front / rear axle (i). I w_ij This is the moment of inertia of the mass of the right / left wheels (j) of the front / rear axle (i). ω ij ' represents the angular acceleration value of the right / left wheel (j) of the front / rear axle (i).
[0046] This is a ratio F for each wheel. x_ij / F z_ij Friction / grip μ is defined as x_ij This yields the value of the coefficient, where F z_ij This represents the vertical load acting on the right / left wheels (j) of the front / rear axle (i), and is known from the values in set 3, making it possible to estimate the values for longitudinal load transfer and transverse load transfer.
[0047] Force Fx ij and Fy ij Once this is known, the calculation module 14 can perform the calculation of drift acceleration according to the diagram shown in Figure 10.
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[0048] Therefore, starting from the computational model described above, it is possible to calculate, based on the steering angle, what the expected yaw rate is for a perfectly symmetric vehicle traveling on a symmetrical road surface. Such values are shown below and in the figures by reference symbols.
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[0049] Actual measured yaw rate
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[0050] The equations derived from calculation modules 14 and 16 are incorporated into equation (2) provided below.
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[0051] Starting from equation (2), by performing subtraction according to equation (1), in particular, the difference
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[0052] Conversely, if the equation is in equilibrium
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[0053] Figure 2B shows a block diagram of the computation module 12, which will be briefly referred to below as the "drivetrain module." In the method according to the invention, the drivetrain module 12 makes it possible to determine the resistance to forward movement that does not belong to the normal behavior of the vehicle. Figures 14 and 15 show the computation model implemented within module 12.
[0054] Specifically, referring to Figure 14, the drivetrain module is configured to process a set of input data 2 (including data and parameters normally available on the CAN network, and not requiring any auxiliary sensors or equipment other than those normally present in the vehicle), and specifically a subset relating to the drivetrain, thereby: - Reference longitudinal acceleration a of the vehicle when no perturbation is present XPTMDL To determine - Actual longitudinal acceleration of the vehicle a XCAN to measure -Reference longitudinal acceleration a XPTMDL and the actual longitudinal acceleration a XCAN Calculate the difference between them - Determine the corresponding additional resistance value.
[0055] Therefore, an additional resistor F D The overall components can be expressed as follows: F D =m(a XPTMDL -a XCAN ) In other words, it is the reference longitudinal acceleration a XPTMDL and the actual longitudinal acceleration a XCAN It is a function of the difference between [two values].
[0056] Referring to Figure 15, the overall equation for the longitudinal dynamics equilibrium of the vehicle can be written in the following form:
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[0057] Fslope is the resultant force of resistance or driving force caused by the slope of the ground (upward and downward). In the adopted coding rules, Fslope is positive when it is resistive and negative when it is propulsive.
[0058] Under those circumstances, the unknown component F D This can be determined as the difference for the case of references where asymmetry does not exist, by essentially subtracting the following two equations. ma XPTMDL =ΣF x_i,j -AeroRes-Fslope (case of reference where asymmetry / perturbation does not exist) ma XCAN =ΣF x_i,j -AeroRes-F D -Fslope (Actual situation where asymmetry / perturbation exists) Therefore: m(a XPTMDL -a XCAN )=F D The vehicle's CAN network provides several operational and dynamic parameters, including: meshing gears Engine rotational speed (rpm) Torque provided by the engine [Nm] Braking torque [Nm] Steering angle [°] Lateral acceleration [m / s 2 ] Pitch angle [°]
[0059] It is important to understand that such data can be obtained from any data network on the vehicle, and not necessarily from the CAN network. For this reason, whenever this explanation refers to the use of data residing on the CAN network, it should be understood that the acquisition may originate from either the CAN network or any other network on the vehicle.
[0060] Therefore, by using such data, vehicle a XPTMDL To calculate the reference longitudinal acceleration value in real time, and to convert it to acceleration a XCAN (Block 20, Figure 2B) can be compared with this, and it is the resistance value F due to the presence of asymmetry in the driving dynamics. D This refers to additional data items available on the CAN network (or any data network on the vehicle) in order to determine this.
[0061] Now, let's move on to some considerations regarding computing. In calculating the reference longitudinal acceleration, several simplification assumptions are preferably adopted due to various parameters that may also be involved in the dynamic equilibrium equations provided above. For example, the mass of the vehicle and the rolling resistance of individual tires may vary as the vehicle travels. In general, significant parameters of the vehicle can be calibrated during travel. Furthermore, sensor fusion logic can be used to minimize the effects of physical variations in such values.
[0062] For example, the vehicle's mass can be updated in real time and / or each time the engine starts, based on calculations of acceleration during low-speed operation. For instance, initial operation (leaving a garage or parking area), which is almost certainly low speed, can be used when the vehicle starts up to detect vehicle acceleration and estimate mass when the vehicle starts up again. This is because such mass can fluctuate from the last known set of data due to, for example, the presence of a larger number of passengers and / or a larger amount of fuel or luggage in the vehicle.
[0063] Parameter F D The availability of this is one basis for determinations that may be made regarding the type of asymmetry occurring on a vehicle, specifically regarding the distinction between asymmetry within the vehicle (setup issues) and asymmetry caused by the ground (aquaplane or uneven road surface).
[0064] It is important to note that such distinctions can be derived from a hierarchy of judgments, where the hierarchy is used, in particular, as a coherence cross-check within the above judgments.
[0065] Referring to Figure 5, parameter F D The determination that can be made based on F D and
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[0066] Difference F D -F X,ASIMThe method then calculates that if the value of such a difference is less than the second threshold Th2, the method determines that the asymmetry is due to the ground. In other words, if the value is less than the second threshold Th2, the method determines that the additional longitudinal resistance F pointing to the ground is due to the ground. D However, the resistance F is derived from the difference in yaw rate (above the threshold Th1). X,ASIM This coincides with, and therefore, the asymmetry can reasonably be attributed to the ground.
[0067] Conversely, in the case of a difference exceeding Th2, there is clearly no coherence between the additional force derived from the interaction with the ground and the additional force that gives rise to the difference in yaw rate. Therefore, the asymmetry can reasonably be attributed to the internal state of the vehicle, for example, to a problem with the vehicle setup. Such a situation arises, for example, when a vehicle sensor is measuring rotational acceleration around the z-axis in the presence of a zero steering angle: this can be attributed to asymmetry (camber, toe-in, or both) resulting from a setup problem.
[0068] Furthermore, it is possible to consider the dynamic characteristics of individual wheels. Specifically, the following parameters are considered: • Wheel rotation speed [rad / s] • Wheel rotational acceleration [rad / s²] 2 ] • Tire pressure [bar]
[0069] Based on such parameters, it is possible to calculate whether the rotation of individual wheels at different speeds can be due to a tire puncture or incorrect camber (or toe-in).
[0070] Furthermore, it is possible to calculate a coefficient of road surface non-uniformity based on rotational speed and rotational acceleration. This is useful for distinguishing between cases where the asymmetry is due to the internal conditions of the vehicle and cases where the asymmetry is due to the road surface conditions.
[0071] Regarding asymmetry caused by the conditions inside the vehicle, parameters such as tire pressure, camber angle, and toe-in angle are primarily considered.
[0072] Thanks to calculation module 14, it is possible to determine whether the vehicle is experiencing side thrust from one of its wheels. If this is the case, it is generally due to an inaccurate toe-in angle.
[0073] Furthermore, it is checked whether the side thrust fluctuates as a function of the vehicle's speed (this applies when the asymmetry is caused by the road surface that generates aquaplane).
[0074] Alternatively, or in combination with the determination shown in Figure 5, parameter F D and
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[0075] Referring to Figure 7, alternatively, or in combination with the determinations in Figures 5 and 6, the parameter F depends on the vehicle speed. D and
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[0076] Referring to Figure 8, frequency analysis is performed on all the wheels of the vehicle, either alternatively or in combination with the determinations in Figures 5, 6, and 7, with particular reference to rotational speed. If the rotational speed frequencies differ between the left and right sides, i.e., if their difference is greater than the fifth threshold Th5, it is possible to rule out the asymmetry being due to the condition of the inside of the vehicle, while a more likely determination is the occurrence of road surface asymmetry (typical situations include driving with two wheels on the roadway and two wheels on the roadside, or driving in a way that is outside the roadway). Conversely, if the frequencies are similar on the right and left sides of the vehicle, it is possible to rule out the asymmetry being due to the condition of the road surface, while a more likely determination is the presence of asymmetry due to the condition of the inside of the vehicle.
[0077] If pressure sensors are provided on the tires, it is also possible to use wheel speed with greater accuracy in logic verification. In fact, if the tire pressure is known, it is possible to calculate the rolling radius with high accuracy. If the latter is known, it is possible to normalize the rotational speed of the tires in a manner that eliminates any fluctuations in rotational speed (relative to other wheels) caused by different rolling radii. Once such alignment is achieved, all differences in rotational speed between wheels (even small entities) can be attributed to the incorrect camber of the wheels. In such a manner, in addition to identifying the incorrect setup, it is possible to calculate which wheels have incorrect camber or toe-in.
[0078] Regarding the calculation of asymmetry caused by the road surface (e.g., aquaplane conditions on one side, gravel on one side, snow on one side), the evaluation is complementary to the previous one.
[0079] First, it is assumed that, upon startup, before it can provide elements useful for detecting road surface asymmetry, the vehicle needs to perform checks for asymmetry resulting from the internal state of the vehicle. Based on recorded data, and with parameters calibrated over time, the vehicle sets a zero reference (which may be either accurate or inaccurate) based on the current setup.
[0080] If a zero reference is found, the vehicle can detect asymmetry caused by the ground, and therefore, obviously, the same set of logic checks as described above are performed by performing a supplemental check (in other words, if the check corresponds to an asymmetric state caused by an incorrect setup of the vehicle, or generally by the internal state of the vehicle, the supplemental (or opposite) check corresponds to an asymmetric state caused by the ground).
[0081] The following lists the detected states that result in any of the following judgments.
[0082] Situation 1:
[0083] The rotational speed frequencies of the right and left wheels are the same or substantially the same: Incorrect setup No asymmetry variation with respect to speed: Inaccurate setup No change in asymmetry over time: Inaccurate setup Additional resistance (in terms of yaw rate) that does not take into account the rotation of the vehicle around the vertical axis → Inaccurate setup.
[0084] Situation 2:
[0085] Different rotational speeds of the right and left wheels: Asymmetry of the road surface As speed changes, the asymmetry changes: road surface asymmetry (possibility of aquaplane) Asymmetry changes over time: Asymmetry of the road surface Additional resistance (in terms of yaw rate) that considers the rotation of the vehicle around the vertical axis z: road surface asymmetry.
[0086] Once the aforementioned decisions (which can correspond to probability analysis) are calculated, they are used in decision analysis, and as a result, the causes of the asymmetry are returned.
[0087] Generally, the speed of the final decision can be higher or lower depending on the calculated probability and the required verification time. If the anomaly is more obvious and therefore more dangerous to the vehicle, the decision will be reached more quickly, as the signs of the anomaly will result in a higher probability value.
[0088] In any case, in a preferred embodiment, it is useful to note that none of the previously described determinations are considered essentially necessary and sufficient to infer the actual cause of the anomaly. All states are hierarchically structured to constitute conditional probabilities that enable the achievement of the final determination. The overall logic diagram is always shown in Figure 1.
[0089] At the operational level, information about inaccurate setups is useful because it allows the driver to, for example, change tires or adjust the toe-in angle before vehicle components are severely damaged. Conversely, information about ground asymmetry can be used by the vehicle's control units to optimize the delivery of drive and / or braking torque. (Other possible items) (Item 1) A method for determining the occurrence of an asymmetric state in an automobile: -Reference yaw rate of the aforementioned vehicle (
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Claims
1. A method for determining the occurrence of an asymmetric state in an automobile: - The stage of determining the vehicle's reference yaw rate, - The step of measuring the actual yaw rate of the vehicle, - A step of calculating the difference between the reference yaw rate and the actual yaw rate, If the difference between the reference yaw rate and the actual yaw rate is greater than the first threshold, the occurrence of the asymmetric state is reported. A method for providing this.
2. When the difference between the reference yaw rate and the actual yaw rate is greater than the first threshold: - A step in determining the reference longitudinal acceleration of the vehicle, - The step of measuring the actual longitudinal acceleration of the vehicle, - A step of calculating the difference between the reference longitudinal acceleration and the actual longitudinal acceleration, - A step in determining additional resistance as a function of the difference between the reference longitudinal acceleration and the actual longitudinal acceleration. The method according to claim 1, comprising:
3. - A step of determining the value of an additional longitudinal force resulting from the calculated value of the difference between the reference yaw rate and the actual yaw rate, - A step of calculating the difference between the value of the additional resistance and the additional longitudinal force, - If the difference between the value of the additional resistance and the additional longitudinal force is less than a second threshold, the asymmetry caused by the ground is reported. - If the difference between the value of the additional resistance and the additional longitudinal force is greater than the second threshold, report an asymmetry caused by the internal conditions of the vehicle. The method according to claim 2, further comprising:
4. - A step of determining the duration of variation of the additional force and the difference between the reference yaw rate and the actual yaw rate, - If the duration of the variation is less than the third threshold, the asymmetry caused by the ground is reported. - If the duration of the variation is greater than the third threshold, report the asymmetry caused by the conditions inside the vehicle. The method according to claim 3, further comprising:
5. - A step of determining the coefficient of variation of the additional resistance with respect to the vehicle speed, and the difference between the reference yaw rate and the actual yaw rate. If the coefficient of the aforementioned variation has a value greater than the fourth threshold, the step of reporting the asymmetry caused by the ground, - If the coefficient of variation is below the fourth threshold, report the asymmetry caused by the condition inside the vehicle. The method according to claim 3, comprising:
6. - A step of determining the frequency of the rotational speed of each wheel of the vehicle, - A step of determining the difference in frequency between the right wheel and the left wheel of the vehicle, - If the difference in frequency between the right wheel and the left wheel of the vehicle is greater than a fifth threshold, the asymmetry caused by the ground is reported. - If the difference in frequency between the right wheel and the left wheel of the vehicle is less than the fifth threshold, the asymmetry caused by the internal state of the vehicle is reported. The method according to claim 3, further comprising:
7. The method according to claim 1, wherein the reference yaw rate is related to a state without asymmetry.
8. The method according to claim 2, wherein the reference longitudinal acceleration is related to a state without asymmetry.
9. The method according to claim 2, wherein the additional resistance has a longitudinal direction.
10. The method according to any one of claims 3 to 6, wherein the asymmetry resulting from the internal condition of the vehicle includes an incorrect setup state.