EP1704065A2

EP1704065A2 - Method and device for regulating the longitudinal acceleration/deceleration of a vehicle

Info

Publication number: EP1704065A2
Application number: EP03818918A
Authority: EP
Inventors: Mark Baijens; Thomas Sticher; Markus Ohly
Original assignee: Continental Teves AG and Co OHG
Current assignee: Continental Teves AG and Co OHG
Priority date: 2002-11-19
Filing date: 2003-11-13
Publication date: 2006-09-27
Also published as: DE10393696D2; WO2004045898A3; JP2006506270A; WO2004045898A2

Abstract

The invention relates to a method for regulating a braking system for motor vehicles comprising a speed regulation unit, which is used to automatically implement a desired vehicle acceleration/deceleration (a). Said method is characterised in that a choice is made between intervention in the braking control system or driving engine control system, or in the braking control system and driving engine control system, that if an intervention is made in the braking control system, an input variable is generated for the braking control system and the braking pressure or braking force is regulated on the basis of said variable, in order to achieve the desired vehicle acceleration/deceleration and that if an intervention is made in the driving engine control system, an input variable for the driving engine control system is generated and the driving motor is controlled on the basis of said variable, in order to achieve the desired acceleration/deceleration.

Description

Method and device for regulating longitudinal vehicle acceleration

The invention relates to a method for controlling a brake system for motor vehicles with a vehicle speed control unit by means of which a desired vehicle acceleration (a) can be set automatically.

The invention also relates to a device for controlling a brake system for motor vehicles with a vehicle speed control unit by means of which a desired vehicle acceleration (a) can be set automatically.

The vehicle speed control units set a predetermined vehicle speed by means of an automatic brake intervention and / or intervention in the drive motor control, in particular as part of a sequence and distance control. The sequence and distance regulations are also called ACC (Autonomous Cruise Control, autonomous

Cruise Control) or ICC (Intelligent Cruise Control) or AICC (Autonomous Intelligent Cruise Control, autonomous intelligent cruise control).

In addition to increasing driving safety, the setting of the specific vehicle deceleration (a) serves in particular the driver's comfort (assistance function). Therefore, the automatic delay should be sufficiently smooth and therefore comfortable.

It is a problem here that the longitudinal vehicle dynamics are influenced by a large number of different sizes or situations, such as acceleration or braking of the vehicle initiated by the driver or automatic intervention by a vehicle dynamics control (ESP) or traction control system (TCS).

The object of the invention is a method and a device for controlling a brake system for motor vehicles with a

Specify vehicle speed control unit, through which a certain vehicle deceleration is set safely and comfortably for the driver.

The object is achieved by the features of the independent claims.

Particularly advantageous developments and refinements of the invention are specified in the dependent subclaims.

The object is achieved according to the invention in that an intervention in the regulation or control of the vehicle brake system is provided in which a brake control input variable is generated and on the basis of the brake control input variable a brake control output variable is generated by which a regulation or control of a brake pressure or a braking force, in order to achieve the desired vehicle acceleration, that an intervention in the regulation or control of the drive motor is provided, in which a drive motor control input variable is generated and on the basis of the drive motor control input variable generating a drive motor control output that regulates or controls the drive motor to achieve the desired one

Vehicle acceleration, and that between an intervention in the regulation or control of the vehicle brake system or an intervention in the regulation or control of the drive otor is selected.

The term “acceleration” is to be interpreted very broadly in the sense of the invention. It means both positive accelerations and therefore an increase in vehicle speed. On the other hand, the term also means negative accelerations, thus a reduction in vehicle speed (vehicle deceleration).

According to the invention, it is provided that a brake vehicle acceleration request is generated as the brake control input variable and a brake pressure or braking force request is generated as the brake control output variable, which is fed to an electronic brake control system, and that a drive is used as the drive motor control input variable otor vehicle acceleration request is generated and a drive motor torque request is generated as the drive motor control output, which is supplied to an electronic drive motor control.

According to the invention, it is provided that the choice between the regulation or control of the drive motor and the regulation or control of the vehicle brake is made in accordance with a decision logic in a coordinator.

According to the invention, it is provided that as coordinator Input variables, the desired vehicle acceleration, a current brake pressure, a current vehicle acceleration and a current drive motor torque are fed to the coordinator.

According to the invention, it is provided that a current brake pressure and / or a current vehicle acceleration are determined or estimated by a model-based calculation.

According to the invention, it is provided that the signal for the current vehicle acceleration is filtered, preferably with a filter of the first order.

It is provided according to the invention that the coordinator unit sets the desired vehicle acceleration in the braking system when an intervention in the brake control is made by a pressure request or a quantity derived therefrom, and that the desired vehicle acceleration is set by an engine torque request in the event of an intervention in the drive motor control or a variable derived therefrom is set in the braking system.

According to the invention, it is provided that a torque that is minimally possible by the drive motor is determined, that the desired vehicle acceleration and a desired torque are ascertained, and that an intervention in the brake control takes place when the desired torque is less than the minimum possible torque.

According to the invention it is provided that a unit for intervention in the regulation or control of the Vehicle brake system (vehicle deceleration control), a unit for intervention in the regulation or control of the drive motor (vehicle acceleration control) and a unit for the selection between these interventions (coordinator) are provided as individual modules in a longitudinal control (Lac).

It is provided according to the invention that the longitudinal control can assume at least three states, a first state (Lac_mode_l), in which only the drive motor is activated, and a second state (Lac_mode_2), in which only at least one vehicle brake is activated, for the purpose Generation of a

Vehicle deceleration, and a third state (Lac_mode_3), in which only the at least one vehicle brake is actuated, in order to generate a low brake pressure, essentially without any noticeable vehicle deceleration, which essentially serves only to overcome the air clearances in the braking system.

According to the invention, it is provided that a transition to the second state (Lac_mode_2) takes place only after a transition to the third state (Lac_mode_3).

According to the invention, it is provided that a jerk limitation is provided which limits the change or the rate of change of the vehicle acceleration.

It is provided according to the invention that the jerk limitation is provided as a module in the longitudinal control (Lac).

According to the invention it is provided that the Longitudinal control (Lac) is provided as a module in an electronic brake control, such as a vehicle dynamics control (ESP), a traction control system (TC) or an engine torque control (TC).

According to the invention, it is provided that in the first state (Lac_mode_l) of the longitudinal control (Lac) a desired torque _V h is determined taking into account a transmission factor and a clutch torque 54, and that from the desired torque T _wh taking drive motor data into account (loss of torque) a corresponding engine torque T _{E is} generated, by means of which the drive motor is controlled or regulated.

It is provided according to the invention that the unit for engaging in the regulation or control of the drive motor (vehicle acceleration control) has an open control loop and a closed PID control loop.

According to the invention, it is provided that a control error is determined by subtracting the, preferably filtered, current vehicle acceleration and a desired, internal vehicle acceleration, is fed to the closed PID control loop as an input signal, and an error acceleration request is determined as an output variable therefrom.

According to the invention, a desired internal vehicle acceleration is supplied to the open control loop as an input signal and a model-based torque request is determined from this.

It is provided according to the invention that by merging the model-based torque request and of the share of the PID control loops an overall acceleration request is formed.

According to the invention, it is provided that the vehicle speed control unit is functionally assigned to a follow-up or distance control, such as ACC system, ICC system or AICC system.

That is what the term means

Vehicle speed control unit in the method and the device according to the invention is expressly not limited to the function or device of a speed controller in the narrower sense (cruise control). Rather, the induction can also be used particularly advantageously in control units for vehicle speed which are functionally or as a structural unit assigned to a sequence or distance control system (ACC systems, ICC systems, AICC systems etc.).

The object is also achieved according to the invention by a device which is characterized in that the system has a vehicle acceleration controller, for controlling the drive motor for setting a specific vehicle acceleration, that the system has a vehicle deceleration controller, for controlling the vehicle braking system for setting a specific vehicle acceleration, and that the system has a coordinator unit for the purpose of selecting the activation of the vehicle acceleration controller or the vehicle deceleration controller.

It is provided according to the invention that a Jerk limiter is provided for the purpose of limiting the change or the rate of change of the vehicle acceleration.

According to the invention, it is provided that the coordinator unit is intended to control the vehicle deceleration controller and / or the vehicle acceleration controller in accordance with the desired vehicle acceleration, the current brake pressure, the current vehicle acceleration and the current drive motor torque.

According to the invention, it is provided that the coordinator unit, the vehicle acceleration controller, the vehicle deceleration controller and the jerk limiter are designed as modular units in a longitudinal controller (Lac).

It is provided according to the invention that the device is functionally assigned to a device for sequence or distance control, such as the ACC system, ICC system or AICC system.

The object is also achieved by an electronic brake control unit, which is characterized in that the device according to the invention is provided as a module in the electronic brake control unit.

According to the invention, it is provided that an overall longitudinal vehicle controller (LVCges) is provided as a superordinate module in the electronic brake control unit, in which essentially all systems regulating the longitudinal control of the vehicle or influencing the control are integrated as modules.

According to the invention, it is provided that the device according to one of claims 21 to 26 is integrated in the higher-level module (total longitudinal vehicle controller, LVC).

According to the invention, it is provided that the overall longitudinal vehicle controller (LVCges) has a superordinate loading controller (LACges) and a superordinate coordinator (LVCges).

According to the invention, it is provided that a device according to the invention or a brake control unit according to the invention is used for an externally actuated, electronically controllable vehicle brake with a hydraulic brake booster by means of a hydraulic pump and with an analogized isolating valve.

The term "isolating valve ^'" a valve is to be understood with which a hydraulic connection between the master brake cylinder and the wheel brakes can be interrupted. The separation valve is designed as a "analogized valve", in particular as "analogized electromagnetic valve". The term " Analogized electromagnetic valves "are to be understood here as electromagnetic valves which assume a certain switching position by actuation with a certain control current, for the purpose of setting a certain volume flow of hydraulic fluid (brake fluid) through the valves. This means that the valve can also assume intermediate positions by appropriate control between a (fully) open position and a (fully) closed position and thus at least approximately a defined one Set the pressure drop between the two sides of the valve.

In this brake system, the driver can control brake pressure in a master brake cylinder by means of an actuating device, preferably a brake pedal, and the pressure controlled by the driver can be increased by means of the active hydraulic pressure increasing unit, the hydraulic pump. If the actuation point of a vacuum brake booster is reached in this system and the brake pedal is pressed further by the driver, then the pressure is increased further by the pump - with insufficient support of the vacuum brake booster - so that the driver receives the desired braking power. Thus, at least part of the brake support can be actively generated by the pump.

In these hydraulic brake systems, an automatic intervention in the brake control can be implemented in a technically particularly simple and advantageous manner by the method or by means of the device according to the invention.

For certain applications, the use of the invention for a brake system with an "active booster" is also preferred, in which an externally controlled, i.e. not directly specified by the driver, build-up of brake pressure is realized by means of a valve on the booster

(Vacuum brake booster), whereby this can be ventilated externally.

The method according to the invention and the device according to the invention will now be explained in more detail by way of example with reference to figures (FIGS. 1 to 12). 1 shows a block diagram for the regulation of the vehicle acceleration,

2 shows an embodiment of the system architecture of the controller for the longitudinal vehicle acceleration,

3 shows a jerk limiter and a coordinator unit,

4 shows various states of the controller for the longitudinal vehicle acceleration,

5 shows a calculation of the drive motor torque from a torque,

6 shows a block diagram of the structure of an acceleration controller,

7 shows an example of a regulation

8 shows a plot of the proportional portion of a print request (Lac_ρrop_ _j ? Art) against a derivation of the control error (Lac_con_err),

9 shows a plot of a differential component of a pressure request (Lac_diff_part) against a derivation of the control error (Del_con_err),

10 shows a plot of an integral part of a print request (Lac_int_part) against a control error sequence (Lac_con_err_sum),

11 shows an example of a regulation with resetting of the integral part, and

12 shows a brake control system with a higher-level longitudinal vehicle controller (LVC).

The system for regulating the longitudinal vehicle acceleration, hereinafter also referred to as “vehicle acceleration” or “acceleration” for short, is shown in FIG. 1 by means of a block diagram.

The vehicle has a follow-up and distance control (ACC) with an electronic unit (ACC-ECU) 1. The ACC unit 1 has a vehicle speed control unit 2, which can be set by the vehicle driver 3. Furthermore, an object distance control unit 4 is provided, to which data from a distance determination unit 5 relating to a preceding object is supplied. This data is based on a Sensor, preferably a radar distance sensor, determined.

A signal is fed from the vehicle speed control unit 2 to a longitudinal controller 7, which is assigned to a brake control unit, in particular a control unit for a vehicle dynamics control (ESP-ECU) 8. The longitudinal controller 7 is also supplied with a signal from the object distance control unit 4 of the ACC system 10. The desired acceleration is implemented by the longitudinal controller 7 according to the invention either by means of a pressure control unit 11 which generates a signal 12 for brake control. However, a signal 13 for an engine control unit (EMS-ECU) 15 can also be generated and transmitted. The engine control unit (EMS-ECU) then controls or regulates the drive motor according to a specific accelerator pedal position (accelerator pedal position or E-gas).

The longitudinal controller 7, also referred to as the “longitudinal acceleration controller” or “LAC controller” or “LAC” for short, is shown in more detail in FIG. 2. The longitudinal controller 7 is preferably a module (LAC module) ) provided in the software of the electronic braking system (EBS software, such as ESP software).

2 shows the longitudinal controller 7 in more detail. The longitudinal controller 7 essentially has the following components:

A jerk limiter 20, which cleans the requested acceleration signal from any jerky changes that are uncomfortable for the driver.

A coordinator unit 21, which has a situation logic motor / brake, which, based on an internal longitudinal acceleration request 26, a current brake pressure 28, a moment 29 and the current acceleration 29, decides which actuator is currently necessary to achieve the desired one Acceleration to put

A deceleration controller 22 which, if the brake is to be controlled or regulated, implements the desired acceleration (usually negative accelerations). This is done by a pressure request 23 to a pressure regulator in the vehicle 24,

An acceleration controller or vehicle acceleration controller 24 which, if the drive motor of the vehicle is controlled or regulated the desired acceleration (usually positive accelerations) is to be implemented. This is done by an engine torque request 25, which is preferably transmitted to the engine control unit via a vehicle bus system, such as CAN.

The structure and the logical queries and steps of these individual components of the longitudinal controller 7 are described in more detail below and with reference to Figure 2 and Figure 3.

If the longitudinal controller 7 receives a longitudinal acceleration request internally or from an external unit such as an ECU, e.g. of an ACC system or from a follow-up control for a stop-and-go driving situation (stop-and-go system) 30, then the controller calculates a corresponding pressure request to the brake system 23 or an engine torque 25 to the engine control system, depending on the current situation, such as acceleration request, current acceleration, vehicle speed or road.

The brakes of the vehicle are then controlled by setting the internal brake pressure request 23 by the brake pressure controller 22, which controls an active booster or a hydraulic brake booster by means of a pump.

An engine torque request 25 is then transmitted to the engine control system via a bus system, such as CAN bus. The longitudinal controller 7 is preferably provided in systems with an electronic accelerator pedal (E-gas). To make a "smooth" transition between brake control and To implement engine torque control, engine control data are taken into account.

After receiving an "ACC deceleration request" (a _rβJ r, Λcc) 30, preferably via CAN bus, the longitudinal controller 7 suppresses any abrupt changes ("jerks") in the acceleration request that are caused by the jerk limiter 20. Such a "corrected" acceleration request ^λ acceleration demand intern "st af 26 is then used as a new acceleration request. The acceleration control unit 24 calculates a corresponding axis torque that is transmitted into an engine torque request T _E 25 ,

In order to differentiate between brake controller 22 and engine controller 24, only a “torque request” 29 is calculated. The request 29 is compared with the minimum possible engine torque 31 that is calculated and sent by the engine control. If the desired torque 29 is below the minimum possible torque 31, the "coordinator brake / motor" 21 activates the brake. If the coordinator 21 switches the brake, the required torque and engine torque are automatically set to the minimum possible value. The LDC (deceleration controller 22) is activated in order to calculate a corresponding brake pressure request P _ref 23. The "brake / motor coordinator" 21 switches the motor only when the pressure request of the LDC 7 is zero and the current brake pressure _ra 28 falls below a certain limit value, which indicates that the desired deceleration can only be set by the motor.

According to the invention, the LAC module 7 therefore includes a deceleration control 24 itself, the “jerk Limitation "20 and the brake / motor coordinator 21. When the brake is active, the LAC module 7 directly addresses the LDC module 22 in order to implement the braking deceleration.

A "vehicle model" unit 32 is additionally provided for certain applications. A particularly sensitive control can thus be implemented in addition. However, embodiments without the "vehicle model" module 32 are preferred. From the "vehicle model" 32, a determined vehicle deceleration is fed to the jerk controller 20, the coordinator 21 and the Bremen controller 22 33, 34, 35. Information from this unit 32 is also transmitted 37 to the acceleration controller 24. The “vehicle model ^ 32” unit determines the data on the basis of vehicle dynamics data 36.

An acceleration signal is determined in the coordinator 21. The acceleration signal 38, 39 is transmitted for the acceleration controller 24 and deceleration controller 22. The signal is a special filtered acceleration signal. It is based on an ABS vehicle reference speed and is calculated from the ABS wheel speed sensors. It is calculated that most vehicles are not equipped with a sensor for longitudinal acceleration.

In the following description and in the figures in FIGS. 4 to 12, certain names or symbols are used for functional units, which are listed in the table.

Abbreviation symbol and meaning

Lac Status Status Lac_req_tor T _wh (Moment Axle torque request limited)

Lac_stat_acc as, ia _c (Static acceleration)

Lac_acc_fil afii.i _ac (Filtered vehicle acceleration)

Lac_dem_lim a _re f (gradient limited acceleration demand)

Lac_a_req_grad

Lac_con_err egg, iao (control error)

Lac_dem_arb a_-ef, _A cc (Arbitrated accel. Demand fro ACC)

Lac_op_lope Rio, iac (Torque demand for open loop)

Lacjorop_part rop.iac (Proportional part of pressure)

Lac_diff_part R - Lff, iac (differential part of pressure)

Lac_int_part Rint, i _ac (Integral part of pressure)

Lac_err_sum EisoM.iac (Control error sum)

Lac_cl_lope Rιc, iac (Torque demand for closed loop)

Lac_err_sume EιsoM, Eff (Effective control error sum)

Lac_veh_acc ae _h , i _ac (Vehicle acceleration)

Lac_pres_dem Rιo, iac (Open loop Pressure demand)

Lac_acc_grad arad, iac gradient of acceleration)

Lac_req_grad Bgr _ad , i _a c (Gradient of brake request) acc_lngaccel aiac (Longitudinal acceleration)

Lac_dem_sg R.t, iac (State of demanded acceleration signal)

Lac_del_err Ed, lac

Lac_req_tor__u Rι, ia _c (Torque demand from LAC unlimited)

Ldc_ p re s_dem P _ref (Pressure demand from LDC Controller)

P_% w P _r e (Wheel pressures)

ReqEngTq T _E (Requested engine torque)

ActTorque T _a (Actual wheel torque)

Lacfrictor T _W h, min (Min. Possible axle torque)

The LAC controller can assume different states (status), a "LAC mode status", a motor status (Lac_mode 1), a brake status (Lac_mode 2) and a brake prefill status (Lac_mode 3) different states can be operated (see Fig. 4). First, the LAC module 7 is activated by signals (Lac__active signals). They cause a reference torque request to be transmitted to the motor controller 25, which then activates the motor to set the desired acceleration. The LAC module 7 can also be activated depending on a moment request 29. The desired acceleration is then set by the LDC brake controller 22.

The bit for which the active LAC module (LAC_STATUS.LAC_ACTIVE) is set regardless of the higher-level system. But "Lac_active" is only set if the LAC function and / or LDC function are not switched off.

The LAC controller 7 can be addressed by an ACC ECU, as in the case of an external torque request via CAN-BUS 30. During an ACC control, Lac_active is set if the conditions are met that an internal actuator request Acc_act_reqi is set.

The LAC mode status of the system is described below.

The status Lac_mode (LAC__STATÜS. AC_MODE) shows the current status (mode) of the LAC controller, the motor mode (engine mode (1)) 41, the brake mode (brake mode (2)) 42, the prefill mode (prefill mode (3)) 43 (see Fig. 4).

In engine mode 41, the LAC module 7 only uses the motor to control the desired acceleration. The brake request is zero (Lac__bra_req = 0). In brake mode 42, the LAC module 7 also activates the LDC controller 22 to control the desired acceleration by brake activation (Lac_bra_req = 1) and at the same time sets the engine torque request to the lowest possible value (T _wh = T _wh , πn).

In prefill mode 43, the LAC module 7 uses the engine control to regulate the acceleration, but the LDC controller 22 is only activated (Lac_bra_req = 1) to fill the brakes. This is done shortly before a correct brake application in mode (2). The pressure requirement is constant during priming, i.e. not dependent on a possible error in the acceleration control.

The jerk limiter 20 provides a smooth transition between longitudinal accelerations if the acceleration request (external ACC, a.χef, _A cc) 30 is replaced by an internal request (a _ref ) 26 (cf. Fig.2).

The internal requirement a _ref is calculated as follows:

After the LAC controller has been activated (Lac_active = 1), the internal request a _rβ f is set to the filtered current acceleration atu, ι _aa for a period of time (loop). Then the internal request a _{ref is followed by} the ACC request a _re f, Αcc with maximum gradient. This ensures a homogeneous transition between driver and ACC control.

The function at the transition from the motor control 41 to the brake control 42 starts when the LAC controller is active (Lac_active = 1), the motor control mode (Lac_mode = 1). Then the LAC control algorithm 24 is turned on desired axle torque T "ι, output 29, which is similar to a minimum possible torque T" _{h / m} i _n (sent from the engine ECU via the CAN Bus). Essentially, the desired torque T " _{h is} similar or less than the smallest possible torque T _Nh , _min 44. The brakes are therefore activated (Lac_mode = 2).

The prefill mode (Lacjnode = 3) 43 is used 45.46 in order to achieve a smooth transition between the motor and brake control and rapid regulation of the brakes in braking mode (Lac_mode = 2) 42. This prefill mode (Lacjnode = 3) 43 is therefore generally upstream of every braking mode 42. Brake prefill mode 43 is started immediately when T " _{h is} slightly above T _{wh / mia} , which indicates the need for brake control 45 (see FIG. 4).

During the transition, clutch actuation by the driver in a vehicle with a manual gearbox and excessive braking (overbraking situation) are also taken into account 47, 48 and 49.

The function of the motor status (engine mode, Lac_mode = 1) 41 is described in more detail below (see Fig. 5).

In motor mode 41, the LAC controller algorithm gives a desired torque “ _h 50, which is converted into a corresponding engine torque T _E 51. A clutch torque 54 is determined by considering 52 a transmission factor 53, from which, taking into account drive engine data (loss of torque) 55 the corresponding engine torque T _E 51 is determined 56. The engine torque T _B 51 is sent to the engine control ECU, preferably via CAN bus. The LAC engine torque Requirement T _E 51 does not meet the other requirements of electronic brake control systems, such as vehicle dynamics control (ESP), torque control (MSR) or traction control (TCS). In this mode, the desired acceleration is realized by the motor alone, i.e. the brakes are not activated (Lac_bra_req = 0), therefore LDC_status = 0 applies.

The function of the brake status (Brake mode, Lacjnode = 2) 42 is described in more detail below (see FIG. 4, see FIG. 2).

In braking mode 42, the braking engine torque is too low to implement the desired negative acceleration. Therefore the brakes are activated. This is done by activating the LDC module 22 (Lac_bra_req = 1).

It follows from this that the Ldc_status is equal to 1, as a result of which the corresponding pressure request P _ref 23 is output. This request 23 itself is implemented by a pressure controller which, for example, controls an active booster or a system with active hydraulic amplification.

The LAC torque requirement T " _h 29 is kept constant at the lowest possible level so that it does not interfere with the LDC controller 22. If the pressure _request P _xef from the LDC module 22 has been calculated as zero and if the pressure in the brakes P _bra itself is zero, then a brake pressure is no longer required. The LAC 7 switches to motor mode 41 or prefill mode 43, depending on the moment T _wh calculated at the moment. The function of the brake prefill status (brake prefill mode, Lac _j node = 3) 43 is now described in more detail (see FIG. 4, see FIG. 2).

In prefill mode 43, the LAC control algorithm 7 also outputs a desired torque T _wh as the engine torque. The brakes are activated by a low, constant pressure request so that the air clearances between the brake disc and brake pad are overcome. To activate the brakes, the LDC module 22 is activated (Lac__bra_req = 1). That means Ldc_status = 1.

Unlike in braking mode, the pressure request remains constant at Lac_ldcj? Refil_j? Res, regardless of current errors in the acceleration control, so that the two controllers 22, 24 are not active at the same time. Depending on the calculated torque T _wh , LAC can switch from engine control 41 to brake control 42.

The structure of the LAC controller 7 (LAC Control Structure) is described in more detail below (see Fig. 6).

The acceleration controller portion 24 of the LAC controller 7 essentially consists of an open control loop (open control loop) 58 and a closed PID controller unit 59. For better control by the LAC controller 7, auxiliary signals (LAC auxiliary signals) are used, whereby the direction of the acceleration request, the gradient of the filtered internal acceleration request and the vehicle acceleration are calculated.

In order to avoid a restless, oscillating engine torque request, the calculated ABS vehicle acceleration Signal a ^ 33, 34, 35, 60 filtered with a first-order filter 61. With a filter _constant Cai, a filtered vehicle _acceleration a _{£ ± lrlac} 62 is calculated from the ABS vehicle _acceleration :

"jHlαc = * ^F ' ^lter (« veh> ^C fll>

From the internal acceleration request 57 and the filtered vehicle acceleration af _± ι _r ι _a α 62, a control error Eι _{f lac is} determined 72 by subtracting and fed 73 to the PID controller 59.

A plot of a _r at, & cc, a _xβ f _m d af ± ι, iaα against the time t for a control process is shown in FIG. 7. If the engine control unit 24 is activated (Lacjnode = 1) 63, 64, the filtered current vehicle acceleration _f ii, ι _{aα is} stored as signal a “ _ιlaα 65. This signal 65 is then used in the calculation of the internal

Vehicle acceleration request a _re ε and used as a signal for the open control loop 58. The signal a _βr ι _aα is only newly determined at the beginning of a LAC motor mode and remains constant via a motor mode loop (see Fig. 7)

The gradient of the internal vehicle acceleration request a _r et 66 is limited to {Lac_accel_dem_ctrad_pos, Lac_accel_ de _grad_neg) in normal situations. In addition, the start value of the internal value a _ref at the start of motor mode 67 is set to the current value (a _Srlaα ) atiχ, iaα (see FIG. 7)

In order to determine the direction {R _at , ι _a c) of the acceleration request, the acceleration request a _ref and the gradient of the filtered acceleration request Bq _∞ d ^ α calculated first. Bgr _a d, ι _aa is calculated by subtracting the previous value of a _ref from the current value and filtering the result with a first order filter. B _g χad, iaa is then used to calculate the direction.

For small gradients of less than 0.125 to 0.165 m / s ³ , in particular about 0.143 less than m / s ³ , the acceleration requirement is regarded as constant, from which follows:

B _g r _a d, ι _∞ = 1 filter (tt _κf , C _ß , ₁ ) and

If iB _gmllιlm <-0.143 ml _S ³ )

Rst, i _ac = 9x01 (decrease) EbeifB _gmVae <0.143 ml s ³ ^R _st , _kc = 0x02 (~ constant) Else

R ^ _a = 0x03 (increase)

To calculate the maximum of the allowed torque request and quick deviations of the

To detect vehicle acceleration, a filtered vehicle acceleration request gradient agrad.iac is calculated. The gradient a _grad , _Iao is calculated by subtracting the previous value of a _f n _rlaa from the current value and filtering the result with a first order filter.

gr <xi, lac --1 "filter ( ^{d (a} M>^<"> / _dt > _C ^

By means of a unit of a model-based instantaneous request “LAC feedforward unit” 70 (see FIG. 6), the approximately linear relation between the Vehicle acceleration and moment in a vehicle on a level road and with a nominal vehicle weight are compensated.

This relation is used to calculate the proportion of the open loop unit 58 of the LAC RO, I _ΛC 71, the current vehicle acceleration being replaced by the desired acceleration. Assuming an ideal acceleration controller, the above equation can be replaced by:

R-IO. _AC - 1 / k * (a "f -a _{St lc} ) and k = (5 / Lac_par_open_tope) ms ² / Nm

The above formula is used for the "feed forward control law" 70. The parameter Lac_par_open_loop is then set on the vehicle.

The LAC feedback part is used to correct all other controller errors, e.g. to compensate for a sloping or rising road surface or different vehicle masses. This is based on the PID controller 59. For comfortable ACC braking, it is important that the LAC signal to the motor controller 24 does not oscillate, but runs smoothly. To achieve this, the controller limits of the PID controller 59 are reduced to zero if the error of the acceleration controller is small.

Examples are shown in Figures 8 to 10. They show the course of the proportionality Signal R _p o _Pr iaa of the differentiated part d ± £ _r iac and the integrated part JR _in t,, jXaa

The proportionality signal po _Pr iaa 75 (Fig. 8) is proportional to the control error E _{1> lac} 76 with a certain range for small controller errors according to the following formula:

If (E _klttc <-0.2m / s ² ) Rp _mp , ι _κ = <®t _he + ° - ² > * iprop _ac >*> ith j ^ _c = Lac_par_propjart * 20 Else if (E _lac <0.2 / s ² )

** - prop, lac ⁼ ^

Else Krop, hc = ^ tte - ^A2 * - _∞ > ^ ^ith ϊ p'op c = Lac_par_prop_part * 20

In order to avoid excessive controller settings, the maximum absolute value of the proportional part R _pxθ p, iaa is limited to Lac_max_proportional_part Nm.

The differentiated signal di ££, ic 77 (see Fig. 9) is proportional to the first derivative (E _dtlac ) 78 of the controller error ι _rl ac with a special width for small controller errors according to the following formula:

Rdmiac = E _äfac * j „ _mkκ , with j _ac = Lac_par_diff_part * 0.14

Else if (Eμ _∞ <0.2 m / s ² )

else

^R ι «= ^« rc * Jβm «' ^with Jdtff = Lac_par_diff_part * 0.14

In order to avoid large controller activities, the maximum value of the differentiated part is £ £, iac limited to Lacjnax_differential_part Nm.

It should be noted that the parameter ac_jpar_d ± f £ _part is zero before the differential part is zero.

The integral Rj „ _t , iac 79 (FIG. 10) is proportional to the sum (E _L SU _MC ) 80 of the controller error E _lιhc with a special accumulation for small control errors:

Rint, iac = E τf; ττ \ f _• ι∞ * »* lac, wkh jint, K = Lac_par_in tjp rt * 0.2

In order to avoid major controller activities, the integral portion Rint, iac is limited to Lac_max__integral_part Nm.

The sum of all parts of the closed circuit 59 ∑ci c 81 (error acceleration request) can be determined as follows:

RlC, lαc = Rpmp, lαc + Rdiff, lαc + Rirtt, lαc

By combining 82 the model-based torque request RW, _IΛ C 71 and the controller component anteilci α 81, an overall acceleration request of the R, iac 83 is formed.

In order to achieve smooth and comfortable acceleration, the acceleration request 83 of the LAC for engine torque control must also be uniform and not oscillating. To achieve this, the gradient of the acceleration request R _L , ι _{ac is} limited 84 (see FIG. 6) The maximum positive / negative gradient of the acceleration request is then:

Lac_max_eng_tor_grad_pos / ac_maκ_eng_ tor_grad_neg.

An engine torque ΪΕ 86 is then determined from the final, limited gradient T _W h 85, taking into account wheel speed sensor data 87 and drive motor data, engine transmission data and transmission data 88. This is preferably done by units of the electronic brake control system.

When the maximum possible actuator torque has been reached, the integral part can be raised if there is a remaining positive accelerator error. This is shown in Fig. 11.

A large integral part will slowly decrease the response time as the acceleration request decreases again. Therefore the following logic is used to set the torque request _Wh to a new start value, reduced by the decreasing integral part when the controller error is negative again.

V [ ^E L, lac ^{<0 and E} LSVM, lac ^{> E} ISUM, EffJ

ELSVM, lac = ElSUM, Bff

The effective controller error sum Eι _S m, Eff is the controller error £ .., .- ac corrected by increasing the integral component according to the formula: V ^ LJac X ») _IS UM, Eff = E _LSÜM , _lac - (** ^T " / j

By correcting the sum of the controller error and the integral part, the required torque is raised to the maximum possible value if the controller error is negative. This prevents a too long delay time (see Fig. 11).

In order to take into account the growing number and complexity of the requirements for the longitudinal control, it is provided that a higher-level module (total longitudinal vehicle control, LVCges) is integrated into the software structure of an electronic brake control system (EBS). This is shown in Fig.12.

In this superordinate module LVCges 99 within the EBS 98, all functionalities are integrated that have to do with the longitudinal control of the vehicle, such as collision avoidance CAS 100, ACC 101, Stop & Go 102 or cruise control 103, which are essentially based on sensor data 115, 116, 117, 118 from vehicle sensors 119 are based. All requirements of these systems, depending on the definition of internal or external requirements, are transferred in a higher-level status coordinator (LVC-state-machine, LVCges) 104 105,106,107,108. The status coordinator 104 determines an entire request from all requests and transmits this 109 to a central, higher-level acceleration controller LACges 110.

Acceleration controller 110 ensures that the request is implemented quickly or conveniently via brake 111 and motor 112. The coordination of the brake 111 and engine 112 is the job of the LACges acceleration controller 110.

A 114 starting module HSA module 113 activated by the status coordinator LVCges 104 is used to start again after stopping from the vehicle.

The LVCges status coordinator 104 can be converted to a number of control modes that are activated as required. For example, a mode for a stand-by mode, a hold vehicle mode (vehicle stops), a stop vehicle mode (vehicle stop), a drive-off mode (vehicle runs), and an acceleration controller are provided Mode (vehicle acceleration), a deceleration control mode (vehicle deceleration) and a pressure control mode (brake pressure control).

These different modes are preferably taken into account in different embodiments of the LACges acceleration controller 110, so that a modular coding of the LACges controller 110 can take place. This enables rapid expansion and adaptation to different systems.

During the control, the individual requested pressures 120, 121, 122, 123 and a requested torque from the LACges acceleration controller 123 are supplied in a downstream coordinator COA and a total engine torque request 124 or a total brake pressure request 125 is generated. The total engine torque request 124 is preferably fed 127, 128 to the drive motor 112 or a transmission or drive 126 via a vehicle bus system (BUS) 126. The total brake pressure request 125 is fed to a brake control unit 129 which controls 130 a corresponding brake pressure. Data from vehicle sensors 134, such as yaw rate, set steering wheel rotation angle, lateral acceleration, wheel speeds, master cylinder pressure, brake pedal force and wheel brake cylinder pressure, are taken into account in the control 131.

An output signal 135 from the brake control unit 129 is also fed to a further unit 136, which generates output signals 137, 138 for the HSA 113 and LVCges 104.

An external acceleration request, in particular from an ACC controller 132, can also be taken into account in the control 133.

In FIG. 12, known modules 139 of the brake control 139 are also shown, which are also integrated in the higher-level module LVCges 99.

This integration is particularly advantageous because a number of new functionalities are expected to be developed (further) in the near future, which will assist the driver in the longitudinal control of his vehicle or autonomously regulate the longitudinal acceleration. First of all, there are systems like ACC, cruise control function with brake intervention or Stop & Go. meant (see Fig. 12). It is envisaged that an ever greater degree of functionality will be transferred to the brake control unit EBS 98.

The different requirements for the longitudinal acceleration of the vehicle caused by the new systems can be via different physical variables (braking pressure, braking torque, deceleration, acceleration) or as binary information, for example “stopping the vehicle”, "Start driving" can be requested. Different systems can also make different demands at the same time. The requests can come from internally or externally via the CAN BUS 126.

Claims

1. Method for controlling a brake system for motor vehicles with a

Vehicle speed control unit by means of which a desired vehicle acceleration (a) can be set automatically, characterized in that an intervention in the regulation or control of the vehicle brake system is provided, in which a brake control input variable is generated and on the basis of the brake control input variable generates a brake control output variable by which a regulation or control of a brake pressure or a braking force takes place, in order to achieve the desired vehicle acceleration, that an intervention in the regulation or control of the drive motor is provided, in which a drive motor control input variable is generated and one based on the drive motor control input variable Drive motor control output is generated by which a regulation or control of the drive motor is carried out in order to achieve the desired vehicle acceleration, and that between an intervention in the regulation or control the vehicle brake system or an intervention in the regulation or control of the drive motor is selected.

2. The method according to claim 1, characterized in that a brake control input variable is a brake Vehicle acceleration request is generated and a brake pressure or braking force request is generated as a brake control output, which is supplied to an electronic brake control, and that a drive motor vehicle acceleration request is generated as drive motor control input and a drive motor torque request is generated as drive motor control output , which is fed to an electronic drive motor control.

A method according to claim 1 or 2, characterized in that the choice between the regulation or control of the drive motor and the regulation or control of the vehicle brake is made in accordance with a decision logic in a coordinator.

Method according to Claim 3, characterized in that the desired vehicle acceleration, a current brake pressure, a current vehicle acceleration and a current drive motor torque are supplied to the coordinator as coordinator input variables.

A method according to claim 4, characterized in that a current brake pressure and / or a current vehicle acceleration are determined or estimated by a model-based calculation.

A method according to claim 5, characterized in that the signal for the current vehicle acceleration, preferably with a filter of the first order, is filtered.

7. The method according to any one of claims 3 to 6, characterized in that the coordinator unit in an intervention in the brake control, the desired vehicle acceleration is set by a pressure request or a quantity derived therefrom in the brake system, and that in the event of an intervention in the Drive motor control the desired vehicle acceleration through a

Motor torque request or a variable derived from it is set in the braking system

8. The method according to any one of claims 1 to 7, characterized in that a minimum possible torque is determined by the drive motor, that the desired vehicle acceleration and a desired torque is determined, and that an intervention in the brake control takes place when the desired torque is less is as the minimum possible moment.

9. The method according to any one of claims 1 to 8, characterized in that a unit for engaging in the regulation or control of the vehicle brake system

(Vehicle deceleration control), a unit for intervening in the regulation or control of the drive motor (vehicle acceleration control) and a unit for selecting between these interventions

(Coordinator) are provided as individual modules in a longitudinal control (Lac).

10. The method according to claim 9, characterized in that the longitudinal control can assume at least three states, a first state (Lac_mode_l), in which only the

Drive motor is controlled, a second state (Lac_mode_2), in which only at least one vehicle brake is controlled, for the purpose

Generation of a vehicle deceleration, and a third state (Lac_mode_3), in which only the at least one vehicle brake is activated, for the purpose

Generation of a low brake pressure essentially without noticeable vehicle deceleration, which essentially only serves to overcome the air play in the brake system.

11. The method according to claim 9 or 10, characterized in that a transition to the second state (Lac_mode_2) takes place only after a transition to the third state (Lac_mode_3).

12. The method according to any one of claims 1 to 11, characterized in that a jerk limitation is provided which limits the change or the rate of change of the vehicle acceleration.

13. The method according to claim 12, characterized in that the jerk limitation is provided as a module in the longitudinal control (Lac).

14. The method according to any one of claims 9 to 13, characterized in that the longitudinal control (Lac) is provided as a module in an electronic brake control, such as a vehicle dynamics control (ESP), a traction control system (TC) or an engine torque control (TC) ,

15. The method according to any one of claims 9 to 14, characterized in that in the first state

(Lac_mode_l) of the longitudinal control (Lac), a desired torque T _wh is determined taking into account a transmission factor and a clutch torque 54, and that a corresponding engine torque T _{E is} generated from the desired torque T _wh taking drive motor data (loss of torque) into account which the drive motor is controlled or regulated.

16. The method according to any one of claims 9 to 15, characterized in that the unit for engaging in the regulation or control of the drive motor (vehicle acceleration control) an open

Control loop and a closed PID control loop.

17. The method according to claim 16, characterized in that a control error is determined by subtracting the, preferably filtered, current vehicle acceleration and a desired internal vehicle acceleration, the closed PID control loop is fed as an input signal and from this an error acceleration request as Output variable is determined.

18. The method according to claims 16 or 17, characterized in that the open control loop is supplied with a desired internal vehicle acceleration as an input signal and from it a model-based torque request is determined.

19. The method according to claim 18, characterized in that an overall acceleration request is formed by merging the model-based torque request and the proportion of the PID control loops.

20. The method according to any one of claims 9 to 19, characterized in that the

Vehicle speed control unit is functionally assigned to a sequence or distance control, such as an ACC system, ICC system or AICC system.

21. Device for controlling a brake system for motor vehicles with a

Vehicle speed control unit, by means of which a desired vehicle acceleration (a) can be set by means of an automatic intervention in the brake control and / or drive motor control, characterized in that the system has a vehicle acceleration controller for the purpose of controlling the drive motor to set a specific vehicle acceleration, so that the system has a vehicle deceleration controller , in order to control the vehicle brake system to set a specific vehicle acceleration, and that the system has a coordinator unit, in order to select the control of the vehicle acceleration controller or the vehicle deceleration controller.

22. The apparatus according to claim 21, characterized in that a jerk limiter is provided for the purpose of limiting the change or the rate of change of the vehicle acceleration.

23. The device according to claim 20 or 22, characterized in that the coordinator unit is provided to control the vehicle deceleration controller and / or the vehicle acceleration controller in accordance with the desired vehicle acceleration, the current brake pressure, the current vehicle acceleration and the current drive motor torque.

24. The device according to claims 22 or 23, characterized in that the coordinator unit, the vehicle acceleration controller, the vehicle deceleration controller and the jerk limiter are designed as modular units in a longitudinal controller (Lac).

25. Device according to one of claims 21 to 24, characterized in that the device is functionally assigned to a device for sequence or distance control, such as ACC system, ICC system or AICC system.

26. Electronic brake control unit, characterized in that the device according to one of claims 21 to 25 is provided as a module in the electronic brake control unit.

27. Electronic brake control unit, characterized in that in the electronic brake control unit an overall longitudinal Vehicle controller (LVCges) is provided as a higher-level module, in which essentially all systems that regulate the longitudinal control of the vehicle or influence the control are integrated as modules.

28. Electronic brake control unit according to claim 27, characterized in that the device according to one of claims 21 to 26 is integrated in the higher-level module (total longitudinal vehicle controller, LVC).

29. Electronic brake control unit according to claim 27 or 28, characterized in that the overall longitudinal vehicle control (LVCges) has a superordinate exposure control (LACges) and a superordinate coordinator (LVCges).

30. Power-operated, electronically controllable vehicle brake with a hydraulic pump for generating a hydraulic brake booster and with an analogized isolation valve, characterized in that the vehicle brake interacts with a device or a brake control unit according to one of claims 21 to 28.