RU2398694C2 - Method and device to control driver style-sensitive automotive subsystem - Google Patents

Abstract

FIELD: transport. ^ SUBSTANCE: set of inventions relates to automotive control appliances. Method to control at least one active subsystem of vehicle chassis comprises determining normalised lengthwise and crosswise acceleration of vehicle. Driver style is estimated by calculating scalar descriptor of driving style on the basis of normalised accelerations, driving style is determined by comparing driving style descriptor with threshold value and subsystem operating state is set up according to determined driving style. Driving style descriptor calculation comprises the step whereat sum of squares of normalised accelerations is calculated. Motorised vehicle comprises chassis with at least one active subsystem and controller 11 to set up operating style of subsystem in compliance with driver's style estimated by comparing driving style descriptor with threshold value. Controller can calculate sum of squares of normalised accelerations. ^ EFFECT: valid determination of driving style, higher safety of driving. ^ 10 cl, 4 dwg

Description

The present invention relates to a method for controlling at least one active subsystem in a vehicle chassis and to a device for performing the method.

Modern vehicles contain a large number of active subsystems that have a significant influence on the way the vehicle responds to the driver’s input signal, such as steering wheel or pedal actions, affecting not only the way the driver “feels” the vehicle, but also driving safety. EP 1355209 A1 discloses a motorized vehicle in which subsystems such as an engine controller, a transmission controller, a steering controller, a brake controller and an air suspension controller can allow different operating states under the control of a master controller. This master controller can receive direct input from the user, for example, through a switch that allows the user to set the type of ground on which the vehicle is moving, and operating modes such as normal, sport, and towing modes. In one of the embodiments of this document, the vehicle mode controller uses information related to the manner in which the vehicle is operated and the method by which the vehicle is used to automatically select the appropriate mode. The powertrain controller and steering angle sensor can be used to classify driving style as normal or sporty. The only disclosed function of the powertrain controller is the distribution of torque on the drive shaft between the front and rear wheels. The determination of the drive mode based on the steering angle sensor should probably give errors, since the steering angle sensor cannot distinguish between actions of the steering wheel during fast movement on a winding road and actions of the steering wheel when maneuvering to or from a parking place.

EP 0 406 615 A2 discloses a method for controlling an active subsystem in a vehicle chassis in accordance with the generic concept of paragraph 1. The active subsystem is a transmission. Management is based on a variety of performance indicators SKP3, SKP4, SKP5, which are functions of vehicle speed and normalized accelerations. There is a need for a method for controlling active subsystems in a vehicle chassis, which provides a reliable determination of a driving style, and a device for performing such a method.

The present invention satisfies this need in the manner of claim 1. The safe acceleration limit is the acceleration at which the vehicle will not be forced to slip.

The calculation of the scalar descriptor of the driving style may include a sub-step for detecting the current operating condition of the vehicle and a sub-step for selecting input parameters for calculation according to the detected operating state. A proper selection of these parameters implements hysteresis for switching to another mode between operating modes.

In addition, it is preferable to take into account not only the total value of acceleration, but also the rate of change when evaluating a driving style.

To this end, the first term representing the average acceleration and the second term representing the average rate of change of acceleration can be calculated, and the descriptor of the driving style can be calculated by forming the sum of the two terms.

If data representing vehicle acceleration is collected at a constant frequency, there is a problem that a given trajectory, if traveling at low speed, will yield more data and thus have more weight in judging driving style than the same trajectory traveling at high speed. This problem is overcome by weighting the data, or, more precisely, the first and / or second members mentioned with a weight coefficient that is progressively related to the vehicle speed.

A sporty driving style can entail high levels of acceleration in combination with moderate steering action, for example, when driving and, as a result, overtaking other vehicles on the freeway; another type of sports driving can entail vigorous steering wheel action at moderate speeds and acceleration levels, for example when driving on a winding mountain road. In order to enable accurate determination in any case, it is preferable that the aforementioned sum of the two terms is a weighted sum, the weights of which are determined based on the actions of the steering wheel.

Preferably, said weights are determined according to the rate of change of the steering angle.

The method is applicable to a variety of active subsystems, such as an all-wheel drive controller, at least one state of which corresponds to an on all-wheel drive mode and at least one state of which corresponds to an off-wheel all-wheel drive mode, and which should preferably be turned off sports mode. Another possible type of subsystem is a shock absorber controller, the states of which correspond to different degrees of depreciation. Here, a condition associated with a sporty driving style should preferably correspond to a higher stiffness of the shock absorbers, so that the tires of the vehicle can maintain a more solid support on the ground. The power steering controller controlled according to the method of the invention may have states that differ in the degree of steering assistance they provide; in a conventional steering controller, there may be states that have different relationships between the steering wheel and the steering angles of the front wheels. There may be states in the powertrain controller that have different gearshift characteristics. In the load controller for controlling the engine load according to the position of the accelerator pedal, there may be states that correspond to different pedal positions / load characteristics. There may be conditions in the brake controller, each of which has a different relationship between the position of the brake pedal and the braking force.

A motorized vehicle for carrying out the present invention comprises a chassis having at least one subsystem, and a controller for setting an operating state of said subsystem according to the driving style of the driver, the controller is adapted to evaluate a driving style based on data representing vehicle acceleration.

The invention may further be embodied in computer program products comprising a code tool for enabling a computer, when the code is executed on it, to execute a method as defined above.

Additional features and advantages of the present invention will become apparent from the following description and the accompanying drawings.

Figure 1 is a structural diagram of a motorized vehicle according to the present invention;

figure 2 - block diagram of the operational sequence of the method according to the algorithm performed by the controller of figure 1;

FIG. 3 is a flowchart showing in detail a step of the method of FIG. 2;

FIG. 4 is a flowchart showing in detail yet another step of the method of FIG. 2.

Figure 1 is a schematic representation of a motorized vehicle, illustrating in a structural form some of the components that are relevant to the present invention. It should be understood that these components are not necessarily essential to the invention and that the invention may also be applicable to components other than those shown.

The steering wheel 1 controls the angle of rotation of the front wheels 2 of the motorized vehicle through the power steering controller 3. The power steering controller 3 has at its disposal the operating factors for turning the front wheels 2 in proportion to the angular position of the steering wheel 1 and the operating factors for manifesting on the steering wheel 1 a torque counteracting the torque applied by the driver. The power steering controller 3 supports a plurality of operating conditions that differ from each other in the degree of assistance provided to the driver, i.e. in proportion to the torque applied by the acting factors to the front wheels and the opposing torque experienced by the driver. The power steering controller 3 further comprises the functionality of the so-called active front steering, that is, it supports a number of conditions having different ratios between the angle by which the driver turns the steering wheel 1 and the corresponding yaw angle of the front wheels 2.

The accelerator pedal 4 controls the load of the engine 5 through the electronic controller 6 of the engine. The controller 6 of the engine supports many conditions that use different characteristics to control the load of the engine as a function of the position of the accelerator pedal. For example, there may be a “calm” state in which the load varies slightly depending on the position of the pedal, and there may be a “dynamic” state in which the load varies greatly depending on the position of the pedal.

The transmission controller 7 controls the gearbox 8 mainly based on the engine speed load detected by sensors not shown on the engine 5. The gear shift lever 9 is connected to the transmission controller 7 so as to enable the driver to choose between different states of the controller 7 transmission, which uses different algorithms to select the gear ratio in the gearbox 8 based on the speed and engine load, or for control with automatic transmission lock full-time number selected by the controller 7 of the transmission.

The transmission controller 7 can also be adapted to switch between a two-wheel drive state and a four-wheel drive state, based on an input from a driver, or automatically, for example, based on driving speed.

The electronic controller 10 brakes controls the response of the brakes, not shown, issued to the wheels of the vehicle, when the driver presses the brake pedal 13. The brake controller 10 may implement conventional brake control circuits, such as an anti-lock braking system or electronic stabilization program, ESP, and the different states of the brake controller 10 may vary in terms of wheel slip allowed before the anti-lock braking system or ESP is activated.

A suspension controller, not shown, is provided to control the stiffness of the suspension of the vehicle wheels, different states of the suspension controller correspond to different degrees of stiffness that it applies to the shock absorbers of the wheels.

All these controllers 3, 6, 7, 10 are connected, as auxiliary controllers or slave controllers, to the master controller 11 by a 12 bus system.

The bus system 12 may have a linear structure in which all the controllers are connected in parallel to the same bus line, and the data transmitted over the bus by one of the controllers is received in parallel by the others.

1, a tire system 12 is shown having a ring structure, with tire segments extending from the master controller 11 to the engine controller 6, from the engine controller 6 to the transmission controller 7, and so on, and finally, from the brake controller 10 back to the master controller 11. In such a bus system, the master controller 11 can determine that the data sent to it has been correctly received by all the controllers if these data, after completing a full turn on the bus system 12, are received intact again in the master controller 11.

The task of the master controller 11 is to resolve various conditions that the auxiliary controllers 3, 6, 7, 10 can admit based on the driving style of the driver. The master controller 11 may be designed to support various operating modes, one in which it selects the status of the auxiliary controllers based on the driver’s behavior, and the other in which it makes a decision based on the data that the driver enters directly, for example, by actuating the switches. Using these switches, the driver can set external parameters that are appropriate for decisions made by the master controller 11, such as road conditions (dry / wet, solid / sandy / dirty, towing mode / without towing, with 2-wheel drive / with drive to 4 wheels, etc.). This latter mode of operation of the master controller 11, being conventional, will not be described in detail hereinafter.

Figure 2 illustrates the method performed by the host controller 11 to determine the driving style of the driver. The main idea of the method of figure 2 is the so-called "surface loading". The name of this term is derived from the notion that there is a limited range of longitudinal and lateral accelerations a _x , a _y in which the vehicle can operate safely, and in a diagram that contains longitudinal and lateral accelerations as orthogonal axes, this region has the shape of an ellipse. Surface loading indicates how much use the driver makes in this safe area.

In the initialization phase of the method of FIG. 2, the estimated value, SUest, surface loading and its time derivative, SUrate, are set to zero in step S1, and the moment count index K is set to one in step S2.

In step S3, the master controller 11 determines the longitudinal acceleration a _x , the lateral acceleration a _y and the vehicle speed v at time K. At step S4, the detected acceleration values a _x (K), a _y (K) are normalized by the corresponding threshold values a _{x , max} and a _{y, max} , are squared, added, and the square root of the sum gives the load SU (K) of the surface at time K:

In the materials of this application, a _{x, max} and a _{y, max} denote the maximum threshold values of longitudinal and lateral accelerations, which the driver must not exceed in order to maintain accurate control of the vehicle. These threshold values a _{x, max} , a _{y, max} may be predetermined for all conditions, or there may be different values of these threshold values stored in the master controller 11, which are selected by the master controller 11 according to the road conditions. The road conditions can be entered directly by the driver through any traditional human / machine interface, or they can be automatically determined by the controller 11 or the appropriate one of its associated auxiliary controllers, for example, based on the detected wheel slippage, activity (anti-lock) of the ABS system, etc.

The loading SU (K) of the surface calculated in step S4 is subject to errors due to inaccuracies in measuring a _x and a _y . In order to reduce the effect of such errors, the estimate of the true surface load, SUest (K), is calculated in step S5 based on the floating average of the previous surface loads and extrapolation based on the previous derivative of SUrate (K-1):

SUest (K) = (1-Tg ₁ ) SUest (K-1) + Tg ₁ SU (K) + T SUrate (K-1) (2)

in this case, T is the time interval between the moments K-1 and K, that is, between the acceleration measurements in successive executions of step S3, and g ₁ is an arbitrary coefficient, for example, at approximately 20 Hz, in the case of a sampling interval T of approximately 10 ms

Derivative of surface loading calculated according to

SUrate (K) = SUrate (K-1) + Tg ₂ (SU (K) -SUest (K-1)) (3)

wherein g ₂ is an arbitrary coefficient, for example, approximately 12 Hz ² .

If it is assumed that the sampling time interval T is constant, a much larger number of acceleration samples a _x , a _y will be taken along a path of a given length if it travels slowly than if it moves fast, so if the driving style is determined directly based on SUest and SUrate, trajectories where the vehicle is slow, tend to be overweight. In order to compensate for this effect, the surface load and its derivative are weighed in step S6 by the speed-dependent weighting factor G (v), an example of which is given in Table 1, whereby we obtain a weighted surface load WSU (K) and a weighted derivative WSUrate (K ):

WSU (K) = | SU (K) | G (v)

WSUrate (K) = | SUrate (K) | G (v)

Table 1
Weight coefficient G (v) v ( km / h ) 0 10 fifty 70 one hundred 150 200 G ( v ) 0 2.7 fourteen 19 27 27 27

You can see that in the speed range below 100 km / h G (v) is directly proportional to the speed of the vehicle. At speeds of 100 km / h and above, G (v) is constant in order to avoid outweighing the short time intervals traveling at exceptionally high speeds.

In step S7, the proportional and derivative terms T _{av, p} (K) and T _{av, d} (K) are calculated based on the weighted load of the surface WSU (K) and the weighted derivative of WSUrate (K).

Based on the operating mode currently set in the master controller, normal or sports, the method branches from step S8 to S9 or S10. At any of these steps, the dividers H _p , H _d are selected for the middle terms T _{av, p} and T _{av, d} according to the current vehicle speed v. The tables in which these dividers are predefined are stored in the master controller 11. An example for a set of dividers H _pc , H _ps , from which dividers H _p , and H _dc , H _ds from which dividers H _d are selected, are given in Table 2. The dividers H _pc , H _dc are associated with the normal mode, and the dividers H _ps , H _ds are associated with the sports mode.

table 2
Dividers for normal and sport modes v ( km / h ) 0 55 90 145 H _ps ( v ) 5 four 3 3 H _pc ( v ) 7 6 5 four H _ds ( v ) 6 6 7.5 7.5 H _dc ( v ) 10 10 eleven 13

Using the dividers H _p , H _d selected from table 2 according to the speed and driving mode, the proportional and derivative indicators I _p , I _{d are} calculated in step S11 according to

As can be seen in table 2, the dividers H _ps , H _ds associated with the sports mode are smaller than the corresponding dividers H _pc , H _dc associated with the normal mode, so that when driving in a similar way in normal and sports modes the resulting indicators I _p , I _d will be greater than in normal mode. In this way, hysteresis is realized, respectively, avoiding unnecessary switching between normal and sports modes, which could annoy the driver if they happened too often. In addition, it can be seen that the divisors H _ps , H _pc for the proportional term decrease with decreasing speed, while the divisors H _ds , H _dc for the derivative term increase with speed. This came in handy for obtaining a wide variation in the numerical values of the indicators I _p , I _d according to the style of the driver, so that a clear solution for one mode or another can be based on these indicators.

по времени угла δ поворота рулевого колеса. Для расчета этой производной может использоваться способ, аналогичный расчету производной SUrate(K) загрузки поверхности на этапе S5.In step S12, the derivative is calculated

the time angle δ of rotation of the steering wheel. To calculate this derivative, a method similar to calculating the surface loading derivative SUrate (K) in step S5 can be used.

Based on these derivatives, a distinction can be made between two different types of sports driving, one that causes high speeds but insignificant cornering movements, such as motorway driving, and the other, at medium speeds, but entailing a lot of cornering movement. In order to enable the leading controller 11 to quickly recognize any of these styles, a weighted sum of the indicators I _p (K), I _d (K) calculated in step 11 is generated in step S13 according to equation (5).

, как проиллюстрировано в таблице 3 в качестве примера, пропорциональный показатель I_p наделяется большим весом, если угловая скорость поворота низка, то есть, если транспортное средство, главным образом, движется прямо вперед или по гладким длинным кривым, что типично для езды по автостраде, тогда как, если есть много движения на поворотах в меняющихся направлениях, член производной наделяется большим весом. Таким образом, получается простой скалярный показатель I_dyn динамичного вождения, по которому стиль вождения водителя может классифицироваться как нормальный или спортивный на основании простого сравнения с пороговым значением на этапе S14. В результате этого сравнения флажковый признак DF динамичного вождения может устанавливаться в ВЫКЛ. (OFF) на S15, если I_dyn находится ниже первого порогового значения, он может устанавливаться во ВКЛ. (ON) на этапе S16, если I_dyn выше другого второго порогового значения, или он может быть оставлен неизменным (S17), если показатель I_dyn находится между этими двумя пороговыми значениями.If the weight coefficient W _g increases depending on

as illustrated in Table 3 by way of example, the proportional index I _{p is} given more weight if the angular speed of turn is low, that is, if the vehicle is mainly moving straight ahead or along smooth long curves, which is typical for driving on a freeway, whereas, if there is a lot of movement on turns in changing directions, the member of the derivative is endowed with great weight. Thus, a simple scalar dynamic driving index I _{dyn is} obtained, according to which the driving style of the driver can be classified as normal or sporty based on a simple comparison with the threshold value in step S14. As a result of this comparison, the dynamic driving flag DF can be set to OFF. (OFF) on S15, if I _dyn is below the first threshold value, it can be set to ON. (ON) in step S16, if I _{dyn is} higher than another second threshold value, or it can be left unchanged (S17) if the indicator I _dyn is between these two thresholds.

Table 3
Weight coefficient W _g

(град/с)

(deg / s) 0 10 thirty fifty one hundred 500 W _g 0.3 0.4 0.5 0.6 0.7 0.7

угла δ поворота рулевого колеса, на этапе S12. Когда цикл этапов с S3 до S16 по фиг.2 выполняется первый раз, способ расчета среднего по фиг.3 включает в себя этапы S21 инициализации, на котором счетчик CT, сумма S и среднее значение av устанавливаются в 0, и S22, на котором ячейки u(0), u(1),..., u(BS-1) буфера, содержащего ячейки BS, устанавливаются в ноль.Figure 3 illustrates the calculation of the average value x in the master controller 11, which value may be a weighted load of the surface WSU or a weighted derivative of WSUrate in step S7 or a derivative

steering angle δ, in step S12. When the cycle of steps S3 to S16 of FIG. 2 is performed for the first time, the method of calculating the average of FIG. 3 includes initialization steps S21, in which the counter CT, the sum S and the average value av are set to 0, and S22, in which the cells u (0), u (1), ..., u (BS-1) of the buffer containing the BS cells are set to zero.

At step S23, a sample x (K) of the quantity x is obtained, which should be averaged.

At step S24, the sum S is incremented by x (K) and decreases by the buffer element u (KmodBS). As long as the CT count is smaller than the size of the BS buffer, u (KmodBS) is zero. Then x (K) is stored in the buffer element u (KmodBS) (step S25), and the count of CT is increased by one (S26).

Step S27 decides whether the count of CT exceeds the size of the BS buffer. If so, the average is obtained by dividing the sum S by the size of the BS buffer; if not, it is obtained by dividing the sum S by the count CT. On this average, the most recent BS samples x (KmodBS), x ((K-1) modBS), ..., x ((K-BS + 1) modBS) all have the same weight, and samples that are older than x ((K-BS + 1) modBS) overwritten in the buffer are not counted.

FIG. 4 illustrates a flowchart of selecting a dynamic flag flag DF based on the dynamic metric I _dyn in steps S14 to S17 of FIG. 2. In the first step S31, the dynamic driving parameter I _dyn (K) is compared with the first threshold value Θ _in . If this threshold value is exceeded, the flag flag DF of dynamic driving is set to ON. in step S32. If the threshold value Θ _{in is} not exceeded in step S31, I _{dyn is} compared with the second threshold value Θ _out in step S33. If this threshold value Θ _{out is} not exceeded, also, the flag flag DF is set to OFF. in step S34. Otherwise, DF is left unchanged.

In a subsequent step S35, the longitudinal velocity v _{x is} compared with the threshold value v _max . If the threshold value v _{max is} exceeded, the flag sign DF remains unchanged; otherwise, it is set to OFF. in step S36. Thus, the flag flag DF can be set to OFF. immediately if the speed is low, for example, indicating parking maneuvers, although the I _dyn driving rate may be well above the Θ _in threshold after a long period of fast driving.

Claims (10)

1. A method for controlling at least one active subsystem (3, 6, 7, 10) in a vehicle chassis, comprising the steps of:
evaluate (S4) the longitudinal acceleration (a _x (K) / a _{x, max} ) of the vehicle, normalized to the threshold value (a _{x, max} ) of acceleration, and the lateral acceleration ( _a (K) / a _{y, max} ) of the vehicle normalized to the threshold value (a _{y, max} ),
evaluating the driver’s driving style by computing (S4-S13) a scalar descriptor (I _dyn ) of the driving style based on said normalized accelerations and determining the driving style by comparing (S14; S31) the driving style descriptor (I _dyn ) with a threshold value, and
set the operating state of the subsystem according to the driving style,
characterized in that the calculation of the descriptor (I _dyn ) of the driving style comprises step (S4), in which the sum of the squares of said normalized accelerations ((a _x (K) / a _{x, max} ), (a _y (K) / a _{y, max} )). 2. The method according to claim 1, wherein the step of calculating (S4-S13) the scalar descriptor (I _dyn ) of the driving style comprises a sub-step in which the current operating condition of the vehicle is detected (S8), and a sub-step in which input parameters for calculation (S9; S10) according to the detected operating state. 3. The method according to claim 1, comprising the step of determining (S5) the rate of change (SUrate (K)) of acceleration and taking into account said rate of change when evaluating. 4. The method according to claim 3, containing step (S11), in which the first term (I _p ) representing average accelerations is calculated, and the second term (I _d ) representing average acceleration changes rates, the descriptor (I _dyn ) of the driving style is calculated by forming the sum (I _dyn ) of the two members (S13) and determining the driving style by comparing the descriptor of the driving style with a threshold value (S14, S31). 5. The method according to claim 4, wherein said first term (I _p ) is the average of accelerations weighted with a weight coefficient (G (v)) progressively associated with the vehicle speed. 6. The method according to claim 4 or 5, in which the said second term (I _d ) is the average rate of change, weighted with a weight coefficient (G (v)), progressively associated with the speed of the vehicle. 7. The method according to claim 4 or 5, in which the sum (I _dyn ) of the two members is a weighted sum, the weights (W _g ) of which are determined (S12, S13) based on the action of the steering wheel, said weights (W _g ) are determined (S12, S13) according to the rate of change of the steering angle. 8. The method according to any one of claims 1 or 2, in which said at least one active subsystem is one of the following:
an all-wheel drive controller (7), at least one state of which corresponds to an on all-wheel drive mode, and at least one state of which corresponds to an off-all-wheel drive mode,
shock absorber controller, the conditions of which correspond to different degrees of depreciation,
steering controller (3) with an amplifier, the states of which differ in the degree of assistance to the driver that they provide,
steering controller (3), the states of which have different relations between the steering angles of the steering wheel (1) and the front wheel (2),
the controller (7) of the power unit, the states of which have different characteristics of gear shifting,
a load controller (6) for controlling the load of the engine (5) according to the position of the accelerator pedal (4), the states of which correspond to different positions of the pedal / load characteristics, the brake controller (10). 9. A motorized vehicle containing a chassis having at least one active subsystem (3, 6, 7, 10), and a controller (11) for determining the operating state of said subsystem according to the driving style of the driver evaluated by comparison (S4-S13) with a threshold value of the descriptor (I _dyn ) of the driving style obtained on the basis of the normalized longitudinal acceleration (a _x (K) / a _{x, max} ) and the normalized lateral acceleration (a _y (K) / a _{y, max} ) of the vehicle,
characterized in that the controller (11) is configured to calculate the sum of squares of said normalized accelerations ((a _x (K) / a _{x, max} ), (a _y (K) / a _{y, max} )). 10. A storage medium containing recorded on it, in computer-executable form, computer program code to enable the computer, when executed on it, to perform the method according to any one of claims 1 to 8 for controlling at least one active subsystem in the vehicle chassis .

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