RU2717121C2 - Method for determination of angular speed of vehicle wheels drifting - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: when determining the angular speed of vehicle wheel drift in the information processing unit in real time based on the signals generated by the pulse sensors on the wheels rotation frequencies and the speed of their change, calculating the vehicle centre of gravity longitudinal speed, average angle of turn of controlled wheels, as well as on the basis of signals on wheel rotation frequencies and adjustment parameters using microcontroller with software, sign and value of drift angular velocity are calculated as value of rear wheels driving speed and/or drift of front wheels and generating control actions on the graphic information output device to inform the driver when approaching the limits of critical mode of wheel drift occurrence.

EFFECT: providing dynamic stabilization of safe vehicle speed at turns, thereby preventing demolition of front wheels and rear wheels (drift) of vehicle, and simplification of used means for obtaining information on dynamic state of vehicle.

1 cl, 3 dwg

Description

The invention relates to the automotive industry, in particular, to methods of active safety of vehicles, consisting in determining the angular velocity of the drift of the wheels of the car and to control the brakes of the car to stabilize the angular velocity of the drift at zero level.

A known method and system for its implementation, used to control the rotation of a vehicle having at least one wheel, which includes at least one sensor device mounted in the wheel, which detects at least one variable wheel during turning the vehicle and generates a signal representing at least one variable of the wheel, and further includes an evaluation device that processes at least one signal and determining at least m Here, one limit value of the angle of rotation in accordance with the result of processing. The sensor device is a wheel force sensor that detects at least one component of the wheel force acting essentially between the road surface and the wheel contact area (see published application US US 2003093208 A1, applicants HESSMERT ULRICH, BRACHERT JOST, SAUTER THOMAS, WANDEL HELMUT, POLZIN NORBERT, publ. 05/15/2003).

The disadvantage of the method and system is the need to equip the wheel with an additional force sensor in the zone of contact of the wheel with the road surface, which limits the scope of the method and system.

A known method and system for predicting the stability of the yaw of the vehicle, which includes the following steps: the beginning of the simulation, starting with the measured state of the vehicle at this particular point in time; receiving information about the upcoming trip within a predetermined period of time; simulation of vehicle movement along a future path for a predetermined period of time; the calculation of one or more indicators of the predicted stability of the yaw of vehicles during simulated movement along a future path for a predetermined period of time; assessment of calculated indicators to determine whether the vehicle will lose control; and, if it is determined that the vehicle will lose control, an alarm is made about this stability system of the onboard yaw system (see patent of European Patent Office EP 2261093 A1, applicants FORD GLOBAL TECHNOLOGIES, LLC and VOLVO CAR CORPORATION, publ. 15.12.2010).

The disadvantage of the method and system is the need for the accumulation, storage and use of additional information for modeling the path along the future trajectory of the car, which is accompanied by a complication of the system.

A known method and device for stabilizing the angle of rotation of a vehicle, based on the use of at least one controllable front axle and / or additional axis with an automatically changeable angle of rotation. Additional stabilization of the movement is achieved by adjusting the changed angle of rotation of the steered front axle and / or the additional axis, taking into account the inclination of the vehicle recognized through the tilt control device when exceeding the maximum tilt, in addition, the deceleration value of the vehicle is determined to reduce this tilt tendency. This counteracts the drift or drift of the vehicle. In addition, additional stabilization of movement is achieved by determining the direction of movement at the point of contact with the wheel of the main axis of the wheel of the additional axis on the controlled additional axis relative to the longitudinal axis of the vehicle and adjusting the angle of rotation of the controlled additional axis on it to reduce the angle of drift of the wheel of the additional axis relative to its direction movement (see US patent No. US 9187121 B2, applicants GERECKE MARC; KOPPER HEIKO; MICHAELSEN ARNE; WABCO GMBH, publ. 11/17/2015).

The disadvantage of this method and device is the automatic control of the angle of rotation of the controlled front or additional axis without regard to the environment, which creates the preconditions for collisions with obstacles.

There is a known method in which pulses from wheel speed sensors are recorded and fed to the input of an information processing unit. Using the values of the wheel speeds, the values of physical variables characterizing the state of the car and the boundary values of physical variables are determined in real time. At the output of the information processing unit, a signal is generated with information about the approximation of physical variables characterizing the state of the car to the boundary values or their excess. Depending on the values of the physical variables and the boundary values of the physical variables characterizing the state of the car, a signal is generated with a control action that prevents the car from colliding with obstacles (see RF Patent No. 2335805, applicants BOZNIKOV SERGEY EVGENIEVICH and ELKIN DMITRIY SERGEEVICH, publ. 10.10.2008) .

The disadvantage of this system is not a wide enough vector of the measured coordinates of the state of the car, and in particular, the angular velocity of the drift wheels.

The closest in technical essence is a device for assessing the position and angle of the spatial orientation of the vehicle. The device sets the current particle distribution range as a predefined range using a filter. It also scatters particles in a given current distribution range to evaluate the position and angle of the spatial orientation of the vehicle using an image. The camera is mounted on a vehicle. The vehicle has front wheels and rear wheels, moves in a front-to-rear direction, and rotates in a vehicle width direction. The device also contains a module for determining vehicle speed and a module for setting the current range of particle distribution. The module for setting the current particle distribution range is configured to expand the current distribution range when the vehicle speed becomes high. EFFECT: increased accuracy of estimation of the position and spatial orientation angle of the vehicle, (see RF Patent No.RU 2626424 C1, Applicant NISSAN MOTOR CO., LTD., Published on July 27, 2017).

The disadvantage of this method is the complexity of the technical implementation of software and hardware for calculating the parameters of the car’s motion using visual odometry methods and the limited capabilities of the video camera when working in the conditions of darkness, precipitation, fog, dust storms, etc., which makes it difficult to use vehicles in real life conditions funds.

The technical problem to which the invention is directed consists in indirect measurements, forecasting and prevention of drift of the wheels of a car.

The stated technical problem is solved in that in the method for determining the angular velocity of the drift of the wheels of a car, in which the signals of at least one of the wheels on each side are recorded and processed, the signals about the frequencies of rotation of the wheels of the car generated by the pulse sensors transmit them through the interface lines to an information processing unit in which the values of the physical variables of the car’s movement are determined and compared with boundary values characterizing the critical state of the car, and formed on during the information processing unit, control signals and transmit them to the graphic information output device and / or hazard indicators to inform the driver who determines and generates further actions for driving the car, characterized in that in the information processing unit in real time based on the generated pulse sensors signals about the frequency of rotation of the wheels of the car and the speed of change calculate the longitudinal velocity of the center of mass of the car, the average angle of rotation steering wheels, as well as on the basis of signals about wheel speeds and tuning parameters, using a microcontroller with software, the sign and the value of the angular velocity of the drift are calculated as the value of the speed of skidding of the rear wheels and / or demolition of the front wheels, and control actions are generated on the graphic information output device to inform the driver about approaching the boundaries of the critical mode of occurrence of wheel drift.

Actions and mathematical calculations are carried out using a microcontroller with appropriate software, which allows implementing the sequence of actions of the method described in the algorithm shown in FIG. 1.

The technical results consist in dynamically stabilizing the safe speed of the car in turns, which prevents the demolition of the front and skid of the rear wheels (drift) of the car and in the simplification of the tools used to obtain information about the dynamic condition of the car and, accordingly, to increase the reliability of safe operation due to it simplicity of design. Simplification of the design leads to a low cost of technical means used in it, and low power consumption due to the lack of introduction of additional physical sensors of primary information necessary to solve the problem. The minimum operable configuration of wheel speed sensors is achieved if at least one sensor is available on each side of the vehicle. The proposed method makes it possible to reliably predict the drift of the wheels of the car before the occurrence of these events.

The claimed invention is illustrated by drawings.

In FIG. 1 presents an algorithm for determining the angular velocity of the drift of the wheels of a car;

In FIG. 2 presents the calculated kinematic diagram of the movement of a car on a bend;

In FIG. Figure 3 shows the experimental time diagrams of the main parameters of the movement of the car when driving in a turn.

FIG. 1 contains computing units for determining the angular velocity of a drift of a car’s wheels, implementing the following method steps:

1 - data input on wheel speeds;

2 - calculation of longitudinal speeds of rotation of the wheels;

3 - calculation of the longitudinal velocity of the center of mass and the difference in the rotational speeds of the pairs of wheels;

4 - calculation of the angle of rotation of the steered wheels;

5 - calculation of boundary velocities of drift, skidding of car wheels;

6 - calculation of boundary values of the steering angle of the steered wheels;

7 - calculation of the angular frequency of the drift of the wheels;

8 - indication of hazardous conditions;

9 - data output to the driver for braking control.

The method of determining the angular velocity of the drift of the wheels of the car is as follows.

The signals generated by the pulse sensors of the vehicle wheel speed are recorded and transmitted through the interface unit to the information processing unit.

In the information processing unit, the values of the physical variables are determined and compared with the true values characterizing the critical condition of the vehicle. Namely, in the real-time information processing unit, estimates of the center of mass velocity, the angle of rotation of the steered wheels, the speeds of the longitudinal sliding of the wheels, the top values of the friction coefficients of the sliding of the wheels, as well as the boundary values of the demolition speeds of the front, skidding of the rear wheels, the boundary values of the steering angles are formed wheels corresponding to the demolition of the front and skidding of the rear wheels, and estimates of the angular velocity of the drift of the wheels of the car. Further, on the basis of signals about the frequencies of rotation of the wheels, and tuning parameters, using the microcontroller with software, control signals are transmitted at the output of the information processing unit to the output device of graphic information and / or indicators of dangerous states to transmit information to the driver about physical parameters characterizing the state of the car , as well as the approximation or exceeding of the boundary values of the drift speeds of the wheels, in this case, at least one medium is additionally activated TVO indicating dangerous conditions to attract the driver's attention.

As a possible implementation of the mathematical model of indirect measurements of the angular velocity of the drift of the wheels of the car Δω _{m, we} use the system of equations of linear speeds of rotation of the wheels V _i 1≤i≤4 at the turn (see Fig. 2):

where Δω _m is the angular velocity of the drift of the wheels of the car;

ΔV _Si is the longitudinal sliding speed of the i-th wheel (1≤i≤4).

In FIG. 2 adopted the following notation:

b - wheelbase of the car;

Ψ ₁ and Ψ ₂ - rotation angles of the 1st and 2nd steered wheels, respectively;

Ψ _c is the average angle of rotation of the steered wheels;

a ₁ and a ₂ - the gauge of the front and rear wheels;

V _i - linear speed of rotation of the i-th wheel (1≤i≤4);

R _i are the turning radii of the respective wheels;

R _m is the turning radius of the longitudinal motion of the center of mass

V _m is the linear velocity of the longitudinal motion of the center of mass;

Ψ _R is the yaw angle;

b * is the distance from the center of mass to the rear axle of the vehicle;

ω _m - the angular velocity of rotation of the center of mass of the car in turn when driving without drift wheels.

The differential equation of the heading angle Ψ _m :

- скорость изменения курсового угла.Where

- rate of change of course angle.

и

в дискретном времени приводится к виду:Solution (2) taking into account the Euler formula

and

in discrete time is reduced to the form:

The increment of the heading angle ΔΨ _m (k) at the kth step is:

In the case of skidding of the rear wheels, ΔΨ _m coincides in sign with Ψ _c for V _m > 0, which leads to an increase in the absolute value of the increment of the course angle. In the case of the demolition of the front wheels Δω _m has the opposite sign Ψ _c , which reduces the modulus of the increment of the course angle. Additional rotation (drift) with a frequency Δω _m occurs around the center of the axis of the front wheels during skidding and relative to the center of the rear wheels during drift.

The cause of the drift of the wheels of the car is the excess of the centrifugal force acting on the wheels of the front and rear axles, the sliding friction forces of the corresponding pairs of wheels in the tire contact patch with the coating in the transverse direction.

формируются по данным измерений частот вращения колес ω_i(k) и настроечных данных свободных радиусов R_ci(k) колес.Grades

are formed according to the measurement of wheel speeds ω _i (k) and the tuning data of the free radii R _ci (k) of the wheels.

и

(1≤i≤4) по известным оценкам

настроечным параметрам b, a ₁≈a, a ₂≈a при Δω_m=0 приведено в алгоритме определенных параметров движения автомобиля (Свидетельство об государственной регистрации программы для ЭВМ №2009616286. ИНКА-СПОРТ Версия 2.0 /Бузников С.Е., Елкин Д.С. // Роспатент, 2009).Solving the incorrect task of determining grades

and

(1≤i≤4) according to well-known estimates

the tuning parameters b, a ₁ ≈ a , a ₂ ≈ a for Δω _m = 0 are given in the algorithm for certain vehicle motion parameters (Certificate of state registration of a computer program No. 20099616286. INCA-SPORT Version 2.0 / Buznikov S.E., Elkin D .S. // Rospatent, 2009).

The system of equations for the speeds of rotation of the wheels of a car on a bend contains 4 equations with 7 unknowns, and the problem of their determination is incorrect.

To convert the task to the correct one, a group of additional conditions is introduced that characterize the properties of the object.

So, in particular, it is characteristic of the object that positive wheel sliding on a horizontal surface is possible only during acceleration, and negative only during deceleration, which corresponds to the consistency of the signs a _m and ΔV _Si (1≤i≤4):

The longitudinal acceleration of the center of mass a _{m is} limited by the maximum sliding friction forces of the wheels, which corresponds to a system of restrictions:

- нижняя граница ускорения центра масс при торможениях,

- the lower boundary of the acceleration of the center of mass during braking,

- верхняя граница ускорения центра масс при разгонах.

- the upper limit of the acceleration of the center of mass during acceleration.

The magnitude and sign of the angular frequency of the drift of the wheels Δω _m depends on the ratio of the centrifugal force and the sliding friction force of the wheels of the transverse direction for the wheels of the front and rear axles and is reduced to the following condition:

where the marginal drift and skid speeds of the wheels V _g1 and V _{g2 are} determined from the conditions of equality of the sliding friction forces of the corresponding front and rear wheels to half the centrifugal force:

where m ₁₂ = (m ₁ + m ₂ ) m ₀ ^-1 ; m ₃₄ = (m ₃ + m ₄ ) m ₀ ^-1 - relative mass distributions on the front (m ₁ + m ₂ ) and rear (m ₃ + m ₄ ) axes to the total mass m ₀ ;

R _d is the dynamic radius of the wheels;

a _dT - traction and brake acceleration;

k _sq is the value of the coefficient of friction of the sliding wheels in the transverse direction;

g is the acceleration of gravity.

Half sums V _i and V _{j of} different sides in accordance with (1) are:

We introduce the concept of error at the kth step of calculations:

E _ij (k) = V _2imj (k) -V _m (k-1) = V _m (k) -V _m (k-1) +0.5 [ΔV _Si (k) + ΔV _Sj (k)].

Given that V _m (k) -V _m (k-1) = α _m (k) ΔT, we obtain

Eij (k) = a _m (k) ΔT + 0.5 [ΔV _Si (k) + ΔV _Sj (k)].

Taking into account the 1st additional defining property of the object (5), we find that the modulus of the sum of terms is equal to the sum of the modules provided that the terms of the terms are identical.

Therefore, | Ei _j (k) | = | a _m (k) | ΔТ + 0.5 | [ΔV _Si (k) + ΔV _Sj (k)] |.

Minimization of | E _ij (k) | on the set of four pairs of wheels of different sides, it is possible to determine the indices of the wheels of a pair i, j, for which the modulus of the sum of the speeds of the longitudinal sliding of the wheels is the smallest possible.

Estimation of the center of mass velocity V _2m (k) = V _m (k) +0.5 [ΔV _Si (k) + ΔV _Sj (k)].

If the longitudinal acceleration estimate

satisfies the constraints of the second pre-determining condition (6), then the estimates of the longitudinal velocity and acceleration of the center of mass are taken equal to V _2m (k) and a _2m (k).

Otherwise, the longitudinal acceleration estimates are taken equal to the boundary ones and V _m (k) is calculated using the equations of the motion model.

In general, an estimate of the velocity of the center of mass is:

For a pair of wheels of different sides, the difference ΔV _ij = V _i -V _j is equal to:

The average angle of rotation of the steered wheels Ψ _c is determined from equation (11) in the form:

The values of the longitudinal sliding velocities of the wheels ΔV _Si , ΔV _Sj and the angular drift frequency Δω _{m are} not available for measurements, therefore, to determine the angle Ψ _c , its estimate containing the first term of the right-hand side of equation (12) is used, namely

и уравнения (12) для Ψ_c позволяет представить оценку

в виде:Comparison of the equation of assessment

and Eq. (12) for Ψ _c allows us to present the estimate

as:

Given the equality of the speeds of the longitudinal sliding of the wheels ΔV _Si = ΔV _Sj we get that:

The solution of equation (14) with respect to Δω _{m is} written in the form:

However, the eigenvalue Ψ _c is unknown and to estimate it, the boundary value of the average steering angle of the steered wheels is used for the case | Ψ _c | ≥ | Ψ _gr |, where | Ψ _gr | = min [| Ψ _gr1 |, | Ψ _gr2 |] replacement used

Accordingly, the modules of the boundary values of the average steering angles of the steered wheels, the excess of which is accompanied by the drift and / or skidding of the car wheels, are determined from (8) in the form:

Boundary velocities and V _gr1 and V _gr2 moduli of boundary angles | Ψ _gp1 | and | Ψ _gr2 | have the property of:

which follows from equations (8) and (16).

Taking into account the 3rd additional determining property (7), the estimate of the angular frequency of the drift of the wheels is determined from equation (15) in the form:

Prediction of the occurrence of wheel drift (Δω _m ≠ 0) of a car is carried out by extrapolating the boundary velocities V _gp1 , V _gr2 , and V _m for a time τ _e and the following inequality is checked:

;Where

;

;

;

;

;

If inequality (19) is satisfied, the hazardous state indicator is activated in the information input and display unit and braking control signals can be generated to reduce the center of mass speed.

To determine the values of the coefficient of friction of the sliding wheels in the transverse direction k _sq , the Kamm circle property is used:

where k _Sdi and k _Sqi are the sliding friction coefficients of the i-th wheel in the longitudinal and transverse directions, respectively;

- топовое (максимальное) значение коэффициента трения скольжения i-го колеса.

- the top (maximum) value of the sliding friction coefficient of the i-th wheel.

The value of k _Sqi determined from (20) is equal to:

The values of k _{Sdi are} determined in accordance with Newton’s third law from the equation of equilibrium of traction and braking forces and sliding friction forces: traction and braking force Fi is balanced by the sliding friction force

F _Si = F _Ni ⋅k _Sdi , where

F _Ni - normal component of the dynamic load on the i-oe wheels.

Module | k _Sdi | determined from the equation of equilibrium of forces:

.For low modulus traction and braking forces according to (21), the friction coefficient of sliding of the i-th wheel in the transverse direction is

.

выполняется с использованием программного обеспечения в процессе движения автомобиля (Свидетельство об государственной регистрации программ для ЭВМ №2007610818 «Идентификация максимальных значений коэффициентов трения скольжения колес автомобиля» / Бузников С.Е., Елкин Д.С. // Роспатент, 2007). Входными данными для решения этой задачи являются измеряемые скольжения S_i колес и текущие значения коэффициентов трения скольжения колес в продольном направлении k_Sdi.Identification

is performed using software in the process of car movement (Certificate on state registration of computer programs No. 2007710818 “Identification of maximum values of sliding friction coefficients of car wheels” / S. Buznikov, D. Elkin // Rospatent, 2007). The input data for solving this problem are the measured slip S _{i of the} wheels and the current values of the coefficient of friction of the slip of the wheels in the longitudinal direction k _Sdi .

For tires of the same model for a uniform surface

The described sequence of steps of the method and the minimum number of technical means used for its implementation allows to achieve the following technical advantages over known methods:

- the ability to predict the drift of the wheels of the car before the occurrence of these events;

- low cost of technical equipment, due to the lack of the need to introduce additional physical sensors of primary information necessary to solve the problem;

- the possibility of functioning in a minimum configuration of wheel speed sensors in the event of the presence of at least one wheel speed sensor on each side of the vehicle;

- reduction of energy consumption due to the lack of additional information sensors and the possibility of using energetically self-sufficient types of sensors, for example, magnetic induction;

- higher operational reliability due to the minimum configuration of the used technical means and their energy self-sufficiency, in particular, sensors of primary information of wheel speeds;

- the possibility of calculated forecasting of the measured physical variables and their dynamic boundaries for using data in an objective control system for their analysis and establishing the causes of accidents.

Claims (1)

A method for determining the angular velocity of a drift of a car’s wheels, in which signals of at least one of the wheels on each side are recorded and processed, signals about the vehicle’s wheel speeds generated by pulse sensors transmit them through the pairing lines to the information processing unit, in which the values of the physical variables of movement are determined the car and compare them with boundary values characterizing the critical condition of the car, and form at the output of the information processing unit control signals and they are transmitted to a graphic information output device and / or to hazardous state indicators to inform the driver who determines and generates further actions for driving the car, characterized in that in the information processing unit in real time based on signals generated by the pulse sensors about wheel speeds the car and the speed of their change calculate the longitudinal velocity of the center of mass of the car, the average angle of rotation of the steered wheels, as well as on the basis of signals about frequent Using the microcontroller with software, the wheel rotation and tuning parameters are used to calculate the sign and magnitude of the drift angular velocity as the value of the drift speed of the rear wheels and / or the drift of the front wheels and generate control signals transmitted to the graphic information output device and / or indicators at the output of the information processing unit dangerous conditions for transmitting to the driver information on physical parameters characterizing the condition of the car, as well as on approaching or exceeding the limit values of speeds drift wheels, in this case, at least one additional means of indicating dangerous conditions is activated to attract the attention of the driver.

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