DE10138620B4 - Adaptive cruise control system and ACC acceleration interface - Google Patents

Abstract

Adaptive cruise control system of a motor vehicle with a drive train coordinator (TSKO) for controlling the drive train of a motor vehicle consisting of the elements drive machine (MT), transmission (GT) and brake system (BR), which for the drive train elements have the corresponding manipulated variables engine torque (MMT), wheel torque (MRD ) and braking torque (MBR) or braking pressure (PBR), the drivetrain coordinator (TSKO) having a device for controlling the distance and speed of an adaptive cruise control system of a motor vehicle, which uses an input variable of the target acceleration of the motor vehicle to produce the necessary manipulated variables engine torque (MMT) and wheel torque (MRD) and braking torque (MBR) or braking pressure (PBR) for the drive machine (MT), the transmission (GT) and the brake system (BR) of the motor vehicle are determined, with a desired acceleration corresponding to the target acceleration using a model of the vehicle longitudinal dynamics Sum wheel torque of the Kraftfa vehicle is determined, and an ACC controller (ACCR), which has a speed control module (GR) and a distance control module (AR), and the actual speed from the predetermined manipulated variables setpoint speed (vSoll) and setpoint distance (dSoll) and the measured input variables (vIst) and the actual distance (dIst) of the motor vehicle, an output quantity of the target acceleration (aSoll) of the motor vehicle is determined and passed on to the drive train coordinator (TSKO), the speed control module (GR) a speed-dependent target acceleration (av) and the distance control module (AR) a distance-dependent target acceleration (ad) form, both of which are fed to a minimum generator (MIN) for determining the target acceleration (aSoll).

Description

The invention relates to an adaptive cruise control system, which is also referred to as ACC (Adaptive Cruise Control) system.

Conventional cruise control systems control vehicle speed to a speed set by the driver. In this case, the problem arises that an excessive approach of the vehicle to a preceding vehicle is undesirable and a minimum safety distance must be maintained.

In the next stage of development of such systems, adaptive cruise control systems have thus been provided which have varying degrees of interaction with preceding vehicles. A general objective of adaptive cruise control systems is to sense objects in the way, such as vehicles in front, and take appropriate action to maintain a safe distance from the driver on the one hand and to maintain the predetermined speed on the other hand.

For example, describes DE 197 55 963 A1 a generic adaptive cruise control system for automatically maintaining a pre-selected by the driver vehicle speed and to lower the vehicle speed at a fall below a minimum distance to a vehicle in front. The distance to the preceding vehicle is measured by a suitable device, for example by means of a radar system or a lidar system.

5 shows the currently used by Volkswagen AG on some models, such as the D1 and the Colorado, used powertrain structure. The driver's request is determined as a motor torque M _MT from a map KF spanned via rotational speed N and pedal value PWG. The motor controller MTST acts as a coordinator in the drive train and implements this driver request torque M _MT directly to the motor MT via the corresponding control variables. The transmission control GTST the driver's request and thus the desire for propulsion is communicated by the value of the PWG and passes this via a switching program to the transmission GT on. The PWG value is, in addition to the speed N of the motor MT and the speed of the motor vehicle, the decisive variable for the shift program of the transmission control GTST.

In ACC mode (ACC: Adaptive Cruise Control), the propulsion request is also formulated by an ACC controller ACCR on the basis of the engine torque M _MT . The ACC controller ACCR includes a distance control device and a cruise control device. Since delays can also be realized with these systems in the ACC mode, the desired deceleration is communicated via the brake setpoint pressure P _{BR of} the brake control BRST or an active brake booster (not shown). The brake BR is then controlled to this target pressure P _BR . The braking pressures P _BR corresponding to a corresponding delay are determined by application and stored in characteristic diagrams (not shown). The engine torque M _MT is delivered to the transmission GT, which converts the engine torque M _MT into corresponding wheel torques M _R.

The described structure has considerable disadvantages in practice, in particular in ACC operation, as described in greater detail 6 is explained. In the 6 For example, a known adaptive cruise control system and its linkage to the powertrain is schematically illustrated, which includes an ACC controller and a motor controller, as in FIG 5 described, includes

In the ACC operation typical acceleration processes as constant as possible accelerations z. 1 m / s. In order to achieve this acceleration, the ACC controller internally calculates a model of the vehicle longitudinal dynamics, wherein as input variables the input desired distance d _desired to the vehicle ahead, the actual distance d _actual measured by the ACC controller to the vehicle ahead, the entered set speed of the own vehicle v _Target and the actual speed v _Ist of your own vehicle can be used. The relative speed to the preceding vehicle, which results from the time sequence of the distance measurements, can also be considered in the consideration. With the drivetrain ratio received from the transmission thus results in a motor torque corresponding to the necessary Summenradmoment. This engine target torque M _MT is communicated to the engine control unit as a nominal value from the ACC controller via the CAN bus. Further, if necessary, a brake pressure P _{BR is} calculated, which is transmitted to the brake system or the brake booster.

Since the PWG (pedal value transmitter) in the ACC mode is zero, the transmission GT is informed via an inverse driving characteristic map KF _{Inv of} a "virtual" accelerator pedal value, which corresponds to the corresponding "driver's request", and which is notified to a shift program SP. This is where the decisive disadvantage arises: the inversion of the driving behavior characteristic results in very high gradients in the driving behavior characteristic field near full load, so that small positive changes in the engine torque result in large changes in the "virtual" PWG. The transmission is thus after a shift z. B. from the 4th to the 5th gear, which the engine torque must increase, immediately after the upshift again initiate a downshift. The result is extremely annoying pendulum circuits for the driver, which can occur several times in longer acceleration processes.

Another disadvantage of this structure is that hardly constant acceleration values can be realized over a relatively long acceleration process, since the resulting acceleration from the engine nominal torque of the ACC system and the current drivetrain transmission is not controlled centrally, but due to the shift strategy of the transmission completely decoupled from the ACC controller rather a coincidence product.

Finally, the application of the ACC controller depends on vehicle and engine-specific data. This has the consequence that each new combination engine, vehicle, sensor must be re-applied and validated.

Furthermore, from the DE 196 24 615 A1 an ACC controller for distance control for a motor vehicle is known, comprising a unit for controlling the distance to an object located in front of the motor vehicle and a unit for controlling the driving speed of the motor vehicle. In this case, the distance control unit generates a distance-dependent desired acceleration, and the speed control unit generates a speed-dependent desired acceleration. The two accelerations are compared and their minimum internally fed to another unit for calculating the manipulated variables for the prime mover and the brake system, which are then forwarded by the ACC system to the engine control and brake control.

The publication DE 198 38 336 A1 describes a system for controlling the movement of a vehicle, which consists of several levels. In a first level, at least one component for controlling the vehicle movement is provided, which in a further level in a refinement comprises at least one component of propulsion and brake. In a third refinement level, this component is structured at least in components propulsion and braking system.

The publication DE 196 04 220 A1 discloses a method and apparatus for controlling the speed of a vehicle, comprising at least one controller adjusting a speed-influencing actuator to which a time-varying desired speed is set, and the speed of the vehicle approximating the speed influenced by this setpoint. The slope of the setpoint supplied to the at least one controller is thereby changed at least in accordance with the actual speed present when the controller is activated and a target speed predetermined by the driver.

The invention is therefore based on the object to develop an adaptive cruise control system that avoids the disadvantages mentioned above.

This object is achieved by an adaptive cruise control system according to claim 1. Preferred embodiments of the invention are subject of the dependent claims.

• – einen Triebstrangkoordinator zur Steuerung des Triebstranges eines Kraftfahrzeug bestehend aus den Elementen Antriebsmaschine, Getriebe und Bremsanlage, der für die Triebstrangelemente die entsprechenden Stellgrößen Motormoment, Radmoment und Bremsmoment bzw. Bremsdruck bereitstellt, wobei
• – der Triebstrangkoordinator eine Vorrichtung zur Abstands- und Geschwindigkeitsregelung eines adaptiven Fahrtregelungssystems eines Kraftfahrzeugs aufweist, die aus einer Eingangsgröße Sollbeschleunigung des Kraftfahrzeugs die notwendigen Stellgrößen Motormoment, Radmoment und Bremsmoment bzw. Bremsdruck für die Antriebsmaschine, das Getriebe und die Bremsanlage des Kraftfahrzeugs ermittelt, wobei aus der Sollbeschleunigung unter Verwendung eines Modells der Fahrzeuglängsdynamik ein der Sollbeschleunigung entsprechendes Summenradmoment des Kraftfahrzeugs ermittelt wird, und
• – einen ACC-Regler, der ein Geschwindigkeitsregelmodul und ein Abstandsregelmodul aufweist, und der aus den vorgegebenen Stellgrößen Sollgeschwindigkeit und Sollabstand des Kraftfahrzeugs und den gemessenen Eingangsgrößen tatsächliche Geschwindigkeit und tatsächlicher Abstand des Kraftfahrzeugs eine Ausgangsgröße Sollbeschleunigung des Kraftfahrzeugs ermittelt und an den Triebstrangkoordinator übergibt, wobei
• – das Geschwindigkeitsregelmodul eine geschwindigkeitsabhängige Sollbeschleunigung und das Abstandsregelmodul eine abstandsabhängige Sollbeschleunigung bilden, die beide einem Minimumbildner zur Ermittlung der Sollbeschleunigung zugeführt werden.

The adaptive cruise control system of a motor vehicle according to the invention comprises:

• A drivetrain coordinator for controlling the drive train of a motor vehicle consisting of the elements prime mover, transmission and brake system which provides the corresponding manipulated variables engine torque, wheel torque and brake torque or brake pressure for the drive train elements, wherein
• - The drivetrain coordinator has a device for distance and speed control of an adaptive cruise control system of a motor vehicle, which determines the required variables engine torque, wheel torque and braking torque or braking pressure for the prime mover, the transmission and the brake system of the motor vehicle from an input variable target acceleration of the motor vehicle, from the target acceleration is determined using a model of the vehicle longitudinal dynamics of the desired acceleration corresponding Summenradmoment the motor vehicle, and
• An ACC controller which has a speed control module and a distance control module, and determines from the predefined manipulated variables desired speed and desired distance of the motor vehicle and the measured input variables actual speed and actual distance of the motor vehicle an output variable setpoint acceleration of the motor vehicle and transfers them to the drive train coordinator,
• - The speed control module form a speed-dependent target acceleration and the distance control module a distance-dependent desired acceleration, both of which are fed to a minimum generator for determining the desired acceleration.

The longitudinal acceleration of the motor vehicle preferably enters into the model of the vehicle longitudinal dynamics, the longitudinal acceleration of the motor vehicle being effected by means of a longitudinal acceleration module optionally installed in the motor vehicle can be determined with subsequent evaluation.

In particular, the model of vehicle longitudinal dynamics has the influencing variables of rolling friction, rotational and translational mass moments of inertia, air resistance and road gradient. In this case, the road gradient can be determined from the longitudinal acceleration of the motor vehicle and the acceleration determined from the vehicle speed.

Preferably, the ACC acceleration interface includes a feedforward control and a superimposed PI controller. Furthermore, the device may have a module torque coordinator, which converts the summation wheel torque, depending on the positive or negative value, into an engine torque or a wheel braking torque.

The drivetrain coordinator is preferably formed by an engine control unit, wherein the output variables of the driveline coordinator are an engine torque, a wheel torque and a brake pressure or braking torque.

Preferably, the target acceleration is transmitted from the ACC system to the driveline coordinator via a CAN bus. The ACC system has a speed control module and a distance control module, wherein the speed control module forms a speed-dependent desired acceleration and the distance control module forms a distance-dependent desired acceleration, which are both supplied to a minimum generator for determining the desired acceleration. Furthermore, the minimum determined by the minimum generator of speed-dependent setpoint acceleration and distance-dependent setpoint acceleration can be subjected to filtering and limiting.

The inventive adaptive cruise control system avoids the disadvantages of the known structure described in the introduction by decoupling the ACC system from the drive train coordination. Significant difference to the known structure is the requirement of propulsion of the ACC system as acceleration. Thus, the application of the ACC system is largely independent of vehicle parameters such as weight, air resistance, rolling friction, etc. and the scope of software in the ACC system is reduced to the calculation of the target acceleration, or holding the desired speed necessary target acceleration.

A further advantage lies in the considerably simplified application of system coordination between the ACC system and the driveline coordinator. Changes in the torque characteristics of the engine no longer have an effect on the ACC system and no longer need to be re-applied and validated.

Preferably, the ACC acceleration interface is combined with a wheel torque-oriented shift strategy in the transmission control unit. The transmission receives the required setpoint wheel torque and determines from the traction force diagram in which gear this wheel torque can be displayed taking into account the motor characteristic curve. Errors are thus avoided. Therefore, the problem of pendulum circuits can be largely excluded by the new structure from the outset

A preferred embodiment of the invention will be described below with reference to the drawings.

1 shows the drive train structure according to the invention in a schematic representation,

2 shows the control circuit for the ACC operation of a motor vehicle according to the invention in a schematic representation,

3 shows a system overview of the ACC acceleration interface,

4 shows the ACC system used in the powertrain structure according to the invention,

5 shows a known drive train structure, and

6 shows a known control circuit for the ACC operation of a motor vehicle.

1 shows a preferred embodiment of a drive train structure with the adaptive cruise control system according to the invention. Via a characteristic KF, a wheel torque M _RD is determined and passed to a drive train coordinator TSKO from the expressed by the pedal value transmitter PWG desire of the driver and the speed V of the motor vehicle.

In ACC operation, the ACC controller ACCR transmits a _desired acceleration a _target to the driveline coordinator TSKO. Thus, the application of the ACC controller ACCR largely independent of vehicle parameters such as weight, air resistance, rolling friction, etc., and the software scope in the ACC controller ACCR is reduced to the calculation of the required target tracking, or holding the desired speed _target acceleration a _target ,

The drivetrain coordinator TSKO, which may be realized by the engine control, determines from a vehicle longitudinal dynamics model for the requested acceleration a _target Summenradmoment necessary. This wheel torque is included in the torque structure of the drivetrain coordinator TSKO as a target size. The drive train coordinator TSKO now determined from the respective manipulated variables engine torque M _MT for the motor MT, wheel torque M _RD for the transmission or the transmission control GT GTST and braking torque for the braking system M _BR BR or the brake control BRST.

2 shows the control loop for the ACC operation of a motor vehicle using the adaptive cruise control system according to the invention in a modification without Radmomentenorientierte switching strategy. From the input variables desired distance d _desired to a preceding object, in particular a motor vehicle, the measured actual distance d _actual , preferably selected by the driver target speed v _{target of} the motor vehicle and the measured actual speed v _{actual of} the motor vehicle, the ACC controller ACCR determines a target acceleration a _Target , which is transmitted via a CAN bus to the acceleration interface BSS. The acceleration interface BSS, which is shown separately here from the driveline coordinator TSKO for better clarification, calculates the sum wheel torque M _RD required for the requested acceleration using a model of the vehicle longitudinal dynamics and transfers this to the driveline coordinator TSKO for further calculation. This generates the manipulated variables engine torque M _MT for the engine MT and target brake pressure P _BR for the brake system BR. Furthermore, a value PWG of a pedal value transmitter is determined from the engine torque M _MT using an inverse driving characteristic map KF _INV and transmitted to a shift program SP of the transmission control (not shown) which selects the corresponding gear ratio. This translation UEB is transmitted back to the driveline coordinator.

3 shows the ACC acceleration interface BSS, which has an optional longitudinal acceleration sensor LBS, an acceleration controller BSR and a torque coordinator. The longitudinal acceleration sensor LBS determines the longitudinal acceleration a _{Lg of} the motor vehicle and makes it available to the acceleration controller BSR. The acceleration controller BSR, consisting of a precontrol and a superimposed PI controller, calculates, based on a model of the vehicle longitudinal dynamics of the motor vehicle taking into account the influencing variables of rolling friction, rotational and translational moments of inertia, air resistance, and a road gradient detection in the presence of the longitudinal acceleration sensor LBS one of the requested target acceleration a _target corresponding sum wheel torque M _RD . This wheel torque can assume both positive and negative values.

This wheel torque M _RD is then forwarded to a torque coordinator MKO, which takes over the conversion of the wheel torque M _RD into a motor setpoint torque M _MT or, in the case of a negative wheel torque M _RD, into a corresponding wheel braking torque M _BR . Furthermore, the torque coordinator MKO has a hysteresis, which prevents too frequent switching between overrun shutdown and reinsertion in the push / pull area. The torque coordinator need not be part of the acceleration interface, but may be implemented in the driveline coordinator when the ACC acceleration interface and the driveline coordinator are executed separately.

4 shows in schematic form the in 1 and 2 illustrated ACC controller ACCR having a speed controller GR and a distance controller AR. The speed controller GR calculates from the input variables setpoint speed v _setpoint , which is preferably predetermined by the driver, the actual speed v _actual , and a limit speed v _Gr, a speed-dependent desired acceleration a _v . The distance controller AR calculates from the input variables actual speed v _actual , relative speed v _Rel between the motor vehicle and a preceding vehicle, actual distance d _actual between the motor vehicle and the preceding vehicle and predetermined target distance d _desired between the motor vehicle and the preceding vehicle a distance-dependent desired acceleration a _d . In a minimum image MIN, the lower of the two accelerations is determined and output after a filtering and a limitation in a filter FT as a target acceleration. The determination of the relative velocity v _Rel and of the actual distance d _Ist can be effected via a suitable radar or lidar system.

To explain the 5 and 6 reference is made to the introduction.

LIST OF REFERENCE NUMBERS

• ACCR

  ACC controller (distance sensor / acceleration controller)

  KF

  Driveability map

  KF _INV

  Inverse driving behavior map

  PWG

  Pedal sensor

  N

  rotation speed

  M _MT

  engine torque

  M _RD

  wheel torque

  P _BR

  brake pressure

  M _BR

  braking torque

  MT

  engine

  GT

  transmission

  BR

  braking system

  MTST

  motor control

  GTST

  transmission control

  BRST

  brake control

  d _target

  Target distance

  d _is

  actual distance

  v _target

  target speed

  v _is

  Actual speed

  v _Rel

  relative speed

  a _target

  target acceleration

  a _lg

  longitudinal acceleration

  automotive

  motor vehicle

  SP

  switching program

  UEB

  Powertrain translation

  TSKO

  Powertrain coordinator

  SP

  switching program

  BSS

  Acceleration interface

  LBS

  Longitudinal acceleration sensor

  BSR

  acceleration controller

  MKO

  torque coordinator

  GR

  cruise control

  AR

  Adaptive Cruise Control

  a _v

  speed-dependent setpoint acceleration

  a _d

  distance-dependent setpoint acceleration

  MIN

  minimum forming

  FT

  Filter with limitation

Claims (12)

Adaptive cruise control system of a motor vehicle with a drivetrain coordinator (TSKO) for controlling the drive train of a motor vehicle consisting of the elements prime mover (MT), transmission (GT) and brake system (BR), the corresponding manipulated variables engine torque (M _MT ), wheel torque (DR) for the drive train elements M _DR ) and brake torque (M _BR ) or brake pressure (P _BR ) provides, wherein the drive train coordinator (TSKO) comprises a device for distance and speed control of an adaptive cruise control system of a motor vehicle from an input variable target acceleration of the motor vehicle, the necessary correcting engine torque ( M _MT ), wheel torque (M _RD ) and brake torque (M _BR ) or brake pressure (P _BR ) for the prime mover (MT), the transmission (GT) and the brake system (BR) of the motor vehicle determined, from the target acceleration using a model of the vehicle longitudinal dynamics of the desired acceleration corresponding Summenradmo ment of the motor vehicle is determined, and an ACC controller (ACCR) having a speed control module (GR) and a distance control module (AR), and from the predetermined manipulated variables setpoint speed (v _setpoint ) and desired distance (d _setpoint ) of the motor vehicle and the measured measured values actual speed (v _actual ) and actual distance (d _actual ) of the motor vehicle an output target acceleration (a _target ) of the motor vehicle is determined and passes to the drivetrain coordinator (TSKO), the speed control module (GR) a speed-dependent desired acceleration (a _v ) and the distance control module (AR) form a distance-dependent desired acceleration (a _d ), both of which are fed to a minimum generator (MIN) for determining the desired acceleration (a _desired ). System according to claim 1, characterized in that the desired acceleration (a _target ) is transmitted from the ACC controller (ACCR) to the driveline coordinator (TSKO) via a CAN bus. System according to one of Claims 1 or 2, characterized in that the minimum determined by the minimum generator (MIN) of speed-dependent nominal acceleration (a _v ) and distance-dependent nominal acceleration (a _d ) is subjected to filtering and limiting in a filter / limiter (FT). System according to one of the preceding claims, characterized in that the system further comprises a transmission control (GTST) and a brake control (BRST). System according to Claim 4, characterized in that the transmission control (GTST) has a shift program (SP) which selects the ratio from the setpoint wheel torque (M _RD ) provided by the drive train coordinator (TSKO) taking into account the engine characteristic. System according to claim 5, characterized in that the shift program (SP) of the transmission control (GTST) determines the translation by means of a tension diagram. System according to one of the preceding claims, characterized in that enters into the model of the vehicle longitudinal dynamics, the longitudinal acceleration of the motor vehicle. System according to claim 7, characterized in that the longitudinal acceleration of the motor vehicle by means of a longitudinal acceleration sensor (LBS) is determined. System according to one of claims 7 to 8, characterized in that the model of the vehicle longitudinal dynamics has the influencing variables rolling friction, rotational and translational mass moments of inertia, air resistance and road gradient. System according to claim 9, characterized in that the road gradient is determined from the longitudinal acceleration of the motor vehicle and the acceleration determined from the vehicle speed. System according to one of the preceding claims, characterized in that the device for distance and speed control has a pilot control and a superimposed PI controller. System according to one of the preceding claims, characterized in that the device for distance and speed control has a module torque coordinator (MKO), the sum of wheel torque (M _RD ), depending on the positive or negative value, in an engine torque (M _MT ) or wheel braking torque (M _BR) is reacted.

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