DE10330922A1 - Intelligent cruise and distance controller has feature to determine the relative distance to a preceding foreign object in the driving lane - Google Patents

Abstract

The automatic control of the travelling speed is assessed in an ongoing process regarding foreign objects (11) in the driving lane. If a foreign object (11) is identified the relative distance and speed between the vehicle and the foreign object (11) are calculated. If no foreign object (11) is detected, the relative speed and distance values can be set to the maximum values. An emergency brake unit (5) is employed in the case that the calculation gives rise to fear of collision with the preceding vehicle.

Description

The The invention relates to a method for automatic adjustment the speed of a vehicle as well as a combined one Tempomat distance controller according to the preamble of claim 1 or 5th

From the publication US Pat. No. 6,044,321 a distance controller for a vehicle is known, with which the vehicle automatically follows a preceding vehicle with a speed-dependent distance. The distance and the relative speed between the vehicles is determined by means of a radar unit, which is arranged in the front area of the following vehicle. If necessary, the following vehicle can be braked by engine measures in order to maintain the required safety distance and a corresponding relative speed. If the engine braking torque is insufficient, a vehicle brake can also be activated.

Furthermore are also cruise control units for Vehicles known over the driver can set a target vehicle speed, from the vehicle automatically is maintained by depending on the current road topography the Air and fuel supply to the internal combustion engine is regulated.

From Starting from this prior art, the invention is the problem underlying the speed of a vehicle in dependence to automatically set a foreign object to be recognized in the traffic lane, being for the case that there is no foreign object in the lane, one predetermined target speed is to be maintained. speed changes should run in particular comfortable, so without jerking movements.

This Problem is inventively in a Method with the features of claim 1 and in a combined Cruise control with the features of claim 5 solved. The under claims give expedient further education at.

at the method according to the invention to the automatic Setting the speed will be in an ongoing process using an object recognition unit the lane to possible foreign objects checked out, where for the Case that a foreign object is detected, the relative distance and the Relative speed between vehicle and foreign object determined become. If no foreign object is detected, the relative speed and the relative distance to predetermined meaningful limits, in particular upper limits are set.

In a subsequent second step becomes an internal setpoint speed as a function of the relative velocity and the relative distance certainly. However, this target speed must not be higher as the driver-specified target speed, and will therefore limited to the latter.

In a third step becomes a nominal acceleration (or nominal deceleration) as a function of the setpoint speed and the actual Vehicle actual speed determined. This target acceleration or set delay will follow in a fourth step in a driving engine torque (in the case a desired acceleration) or in a decelerating braking torque (in the case a set delay) implemented.

at the method according to the invention become a distance controller and a speed controller to a Combined cascade control summarized. The advantage of the process lies in a better control quality and in particular in a smooth implementation of speed changes, when following a preceding vehicle or when approaching another foreign object, which may also stand still can, automatically carried out become. The method combines the functionality of one Cruise control unit, at a constant, predetermined by the driver target speed independently from the current street topography is complied with, with the functionality of a distance controller, with whose assistance the vehicle follows a preceding vehicle or also braked the vehicle in front of a stationary obstacle becomes. The transition between the cruise control function and the distance control is continuous and for the Driver comfortable.

Another advantage is that already existing vehicle control units can be used and combined to the cruise control distance controller. The distance controller and the speed controller are cascaded in series, wherein in particular in the event that no foreign object is detected on the specification of a high relative speed and a high relative distance to fictitious, meaningful or upper limits a high fictitious target speed is determined, which then on the Driver-specified speed is limited by the driver. The large, fictitious relative distance or the relative speed also make it possible, even in the event of obstacle-free driving with cruise control function, to travel through the distance controller, whereby due to the high values it is ensured that the distance from the dis In any case, the target speed to be determined by the speed controller is above the desired driver speed and is then limited to the latter value. With this procedure, a unified procedure is achieved both for the case of an obstacle in the lane or of a vehicle ahead as well as in the case of the exclusive cruise control function.

It is useful in addition to the process checked, whether an emergency or in the case of a foreign object in the lane an im relationship to the current vehicle speed and considering of safety criteria too small relative distance to the obstacle is present. If so, an emergency delay is determined with which the vehicle is delayed becomes. The value of the emergency delay in particular as a function of the relative distance and the relative speed determined to ensure that the vehicle is in front of the foreign object comes to a standstill.

It is useful between a comfortable delay, which is perceived by the driver as pleasant, and an emergency delay distinguished, where the actual value of the delay on the comfort delay is set, if there is no emergency or if the remaining Distance between vehicle and foreign object allows this. Is against it an emergency or is the distance for the comfort delay too low, the emergency delay is switched and the Vehicle braked accordingly.

at the cruise control distance controller according to the invention becomes a distance controller with a speed controller in cascade form connected together. about a cruise control knob Object recognition unit to be assigned can be located in the lane Foreign object will be detected and will be relative speed as well Relative distance between vehicle and foreign object determined. If If there is no foreign object in the traffic lane, values for the relative speed become and given the relative distance.

relative speed and relative distance are used as input signals to the distance controller supplied in which a desired speed is determined. This calculated Target speed, however, is in any case on one of the driver predetermined driver target speed limited by the cruise control distance not be exceeded may.

In the speed controller connected downstream of the distance controller under consideration of Target speed, which the distance controller as input signal supplied is, as well as the actual speed of the vehicle a target acceleration - if necessary a set delay - or a Function history for determines the target acceleration or target deceleration. The value the calculated setpoint acceleration or setpoint delay is then called Control signal to one or more vehicle units for implementation fed into a driving engine torque or a delayed braking torque. It these aggregates are in particular accelerating or delay plate, which are controlled by the cruise control, in particular for adjusting the air supply to the cylinders of the internal combustion engine and to adjust the fuel supply and / or adjustment a vehicle brake and possibly other aggregates over which the Drive or braking power of the vehicle can be influenced, for example a variable turbine geometry.

Further Advantages and expedient designs are the further claims, the figure description and the drawings. Show it:

1 a schematic representation of a cruise control distance controller including an object detection unit for detecting the relative distance and the relative speed to a preceding or preceding foreign object,

2 a flow chart with individual process steps for automatically setting the speed of the vehicle with cruise control function and distance controller,

3 the structure of an emergency unit for determining an emergency delay, with which the vehicle is braked if the relative distance of the vehicle to the foreign object is below a critical safety distance or another emergency exists.

The in 1 illustrated cruise control distance controller 1 is installed in a motor vehicle and serves on the one hand for automatically maintaining a predetermined vehicle target speed and on the other hand to maintain a safety distance to a lying in the lane of the vehicle or moving foreign object. The cruise control 1 is an object recognition unit 2 associated with a foreign object 11 can be detected, which is located in the lane of the vehicle, and _is connected to the particular of the relative distance and the relative velocity .DELTA.v .DELTA.s _between the vehicle and the foreign object 11 can be determined. The object recognition unit 2 suitably includes a radar unit, but may also be based on other principles, for example on optical detection, distance and speed measurement by laser or the like.

The in the object recognition unit 2 certain relative velocity .DELTA.v _is as well as the relative distance _is .DELTA.s be a distance regulator 3 supplied as input signals, which is part of the cruise control distance controller 1 is. As additional input information is the distance controller 3 a relative desired distance Δs _{soll is} supplied, which can be determined as a function of different state variables and in particular depends on the actual vehicle speed. In the distance controller 3 From these input signals, a provisional target speed v ^* _{soll is} determined.

If from the object recognition unit 2 No foreign object is detected in the lane of the vehicle, the relative velocity .DELTA.v _is and the relative distance .DELTA.s _{is set} to fictitious, upper limits .DELTA.s _max and .DELTA.v _max that the distance controller 3 be supplied as input signals. By specifying the upper limit values, an internal value v ^* for the setpoint speed _to generate, which occupies a very high value. This provisional value for the target speed v ^* _should become a limiter 6 in the cruise control 1 supplied, in which a limitation of the target speed to the driver predetermined driver target speed V _{F, is to be} performed. In this way, it is ensured that the calculated setpoint speed v _soll can not become higher than the setpoint speed v _{F, set} by the driver

The setpoint speed v _soll then becomes a speed controller 4 within the cruise control 1 supplied as an input signal, in addition, the vehicle speed v _is supplied as an input signal in a vehicle state sensor unit 7 has been determined. In the speed controller 4 a provisional value for the nominal acceleration (or nominal deceleration) a ^* _{soll is} determined. The provisional value for the desired delay a ^* _soll is subsequently an adder 12 supplied, in which the target delay a ^* _should by adding up a share .DELTA.a _{Not, should be set} to an emergency delay a _{Not, should be set} as the desired delay a _soll .

The emergency delay is a _{distress, supposed to} be in an emergency unit 5 as a function of the relative reference distance .DELTA.s _to, the relative distance and the relative speed _is .DELTA.s .DELTA.v _is determined. About the emergency delay .DELTA.v _{is to} ensure that in the event of a relative distance .DELTA.s _{is intended to} below a safety-critical desired distance .DELTA.s or any other emergency, the vehicle is decelerated in a short time either to a halt or at least to reach the safety critical distance to the foreign object. If there is no emergency, the value for Δa _{Not, should be set} to 0, so that as target deceleration a _should in the speed controller 4 determined value is reused. The in the speed controller 4 Generated target acceleration is determined under ride comfort criteria.

The target vehicle acceleration a _{is to} become a conversion unit 8th supplied as an input signal, in which the vehicle target acceleration is converted into an engine torque. This engine torque is dependent on the sign of the vehicle target acceleration either as engine braking torque M _Br one or more delay actuators 9 or as the drive torque M _Mot one or more acceleration control 10 fed. To decelerate the vehicle, in particular the air supply or the fuel injection is throttled and possibly also the vehicle brake is actuated. To accelerate the vehicle, air supply and fuel injection can be increased.

The procedure for automatically setting the speed of the vehicle in both cruise control and distance control modes is shown in FIG 2 shown. In a first method step V1, the object recognition unit is used 2 the relative speed _is △ v and the relative distance .DELTA.s _is determined to foreign object. In method step V2, it is determined whether a foreign object is actually in the lane. If this is not the case, the no branch is continued corresponding to the method step V4, in which the vehicle target speed v _{is set} to the driver setpoint driver speed v _{F, should be} set; the vehicle is being moved in cruise control mode.

Provided that a foreign object is in the lane, the yes branch is continued according to the process step V3, in which the target vehicle speed v _{soll is} as a function of the relative velocity .DELTA.v, the relative distance .DELTA.s _is, the relative reference distance .DELTA.s _should and the driver Target speed v _{F, should be} determined. The setpoint speed v _should , however, under no circumstances be higher than an optional driver setpoint speed v.sub.f _{, should} . The method step V3 is in the distance controller 3 carried out.

The calculated target speed v _soll is in the next step V5, which in the speed controller 4 is performed, the calculation of the provisional Sollbeschleuni movement a ^* _{should be} based, which also _{depends on} the actual vehicle speed v _is.

The provisional target acceleration a ^* _soll is then in the process step V9 the adder 12 supplied, in which to the determined value of the target acceleration, an additional value Δa _{Not, should be} added if the remaining braking distance to the obstacle below the safety-relevant value or another emergency exists.

The calculation of whether an emergency exists is made in a parallel branch in steps V6, V7 and V8 in the emergency unit 5 carried out. In accordance with method step V6, Δv _is dependent on the relative velocity and the relative distance Δs _is and the relative nominal distance Δs _{soll is} first of all determined as to whether an emergency actually exists. If this is not the case, the no branch is continued corresponding to the method step V8, in which the in the adder 12 value added to method step V9 is set to 0. Otherwise, the yes branch is continued corresponding to step V7, in which the emergency delay a _{Not, should be} determined and a corresponding difference value Δa _{Not, is} the adder V9 is supplied.

From the addition of provisional nominal acceleration a ^* _soll and the difference value Δa _Not, the emergency deceleration is to determine in V9 the final target acceleration or deceleration a _{so ll} , which subsequently in method step V10 in the deceleration actuators 9 or acceleration actuators 10 is carried out, in an engine braking torque M _Br or a motor drive torque M _{Mot is} converted.

3 shows a schematic of the emergency unit 5 , First, in a first subunit 5.1 _is a function of the actual vehicle acceleration or deceleration a, the vehicle speed _v, the relative distance .DELTA.s _is, the relative reference distance .DELTA.s _to and the relative velocity .DELTA.v _is determined, the braking distance, which is required to the vehicle from the detected foreign object decelerate , The actual braking distance s _{Br is determined} , which _is required starting from the current vehicle acceleration or vehicle deceleration a, in order to decelerate the vehicle. In addition, a minimum braking distance S _{Br, min} and a comfort braking distance s _{Br, komf are} calculated, wherein the minimum braking distance S _{Br, min of} the emergency deceleration a _Not, and the comfort braking s _{sbr , komf} the comfort deceleration a _{comf , should be} equal.

The minimum braking distance S _{Br, min} as well as the comfort braking distance s _{Br, komf} become another subunit 5.2 supplied, in which the required delay a is determined, which is also limited to a maximum allowable value a _max . The delay value a becomes dependent on the actual relative distance Δs _is in subunits 5.3 and 5.4 the value for the emergency delay a _{not, should be} determined. The subunit 5.3 corresponds to the far range, the subunit 5.4 the proximity between the vehicle and the foreign object. In the subunits 5.3 and 5.4 For distance and short range, different control algorithms or calculation rules for determining the emergency delay can be stored. It may be appropriate to have weights between those in the subunits 5.3 and 5.4 to determine the emergency delays identified and to determine the resulting value of the emergency delay from portions of both subunits.

Claims (6)

A method for automatically setting the speed of a vehicle, comprising the following steps: a) detecting a possible foreign object in the lane of the vehicle and determining the relative speed (Δv _is ) and the relative distance (Δs _is ) between the vehicle and foreign object, b) determining a target speed (v _{soll) (is} △ v) as a function of the relative velocity and the relative distance _(.DELTA.s), where the setpoint speed (v _soll) to a predetermined by the driver, the driver-set speed (v _{F, soll)} is limited) determining c a target acceleration or Target deceleration (a _soll ) as a function of the setpoint speed (v _soll ) and the actual speed (v _ist ), d) conversion of the setpoint acceleration or set deceleration (a _soll ) into a driving engine torque (M _Mot ) or a decelerating braking torque (M _Br ). A method according to claim 1, characterized in that in the event that no foreign object is detected, the relative speed (Δv _is ) and the relative distance (Δs _is ) to predetermined upper limit values (Δv _max , Δs _max ) are set. The method of claim 1 or 2, characterized in that a comfortable deceleration permitting comfort delay (a _{Komf, soll)} as well as a maximum emergency delay (a _{distress, soll)} is determined, wherein the target acceleration and target deceleration (a _soll) basically to the comfort delay (a _{Komf, soll} ) is set and only in the event that the braking distance for a stop of the vehicle in front of the foreign object ( 11 ) At a comfort delay (a _{Komf,) is} not sufficient, the target deceleration (a _soll) to the emergency delay (a _{distress, soll)} is set. A method according to claim 3, characterized in that the emergency delay (a _{Not, soll} ) as a function of the relative distance (Δs _is ) and the relative speed (Δv _is ) is determined. Combined cruise control distance control ( 1 ) for a vehicle, in particular for carrying out the Method according to one of claims 1 to 4, - with an object recognition unit ( 2 ) for recognizing a foreign object ( 11 ) in the lane of the vehicle and determining the relative speed (Δv _is ) and the relative distance (Δs _is ) between the vehicle and foreign object ( 11 ), - with a distance controller ( 3 ) for determining a setpoint speed (v _soll ) as a function of the relative speed (Δv _ist ) and the relative distance (Δs _ist ), wherein the setpoint speed (v _soll ) can be limited to a driver setpoint speed (v _{F, soll} ) specified by the driver, with a speed control ( 4 ) for determining a desired acceleration or setpoint deceleration (a _soll ) as a function of the setpoint speed (v _soll ) and the actual speed (v _ist ), wherein the setpoint acceleration or deceleration (a _soll ) associated with vehicle units for conversion into a driving engine torque (M _Mot ) or decelerating braking torque (M _Br ) can be supplied as actuating signals. Cruise control according to claim 5, characterized in that an emergency unit ( 5 ) for reducing the target deceleration (a _soll ) to an emergency deceleration (a _{Not, soll} ) is provided in the event that the braking distance for a stop of the vehicle in front of the foreign object ( 11 ) with a comfort delay (a _{Comf, soll} ) is not sufficient.