DE102007058416A1 - Motor vehicle's e.g. car, movement direction detecting method, involves detecting torque transmitted by vehicle clutch, and adapting prediction of movement direction of vehicle by considering vehicle speed and torque transmitted by clutch - Google Patents

Abstract

The method involves detecting speed of a vehicle e.g. car, and predicting a movement direction by using a mathematical movement model. Torque transmitted by a vehicle clutch is detected, and the prediction of the movement direction is adapted by considering the vehicle speed and the torque transmitted by the clutch. The speed is partially determined by number of rotation sensors, where the mathematical movement model considers vehicle-specific factors. The prediction is changed during a zero crossing of the speed.

Description

The The invention relates to a method for detecting the direction of movement a vehicle, wherein the vehicle speed detected and means of a mathematical model of motion predicts the direction of movement is according to the preamble of independent claim 1.

State of the art

motor vehicles in the art usually Wheel speed sensors to, for example, anti-lock braking systems (ABS) with statements about to supply the state of motion of the wheel or of several wheels. These speed sensors usually determine the amount of wheel speed, but not the direction of rotation. In order to can make no statement about it by means of the wheel speed sensors be whether the corresponding vehicle moves forward or backward. The knowledge of Movement direction, however, is especially in vehicles with automated Driven in the powertrain, such as an automated Manual transmission or a parallel transmission of essential Meaning, in general determine if the vehicle is in the preferred by the gear selection Vehicle direction is driving.

Around determine the rolling direction of the motor vehicle, although in principle known speed sensors are used, the one information about the direction of rotation and not just about provide the absolute value of the speed, but these are usually for cost reasons not used in vehicles.

Object of the invention

The The object of the invention is reliable and / or simple and / or less expensive Provide direction detection method.

Description of the invention

The Task is solved by a method according to the features of independent claim 1, in particular by a method for detecting the direction of movement of a vehicle, wherein the vehicle speed detected by means of a mathematical Movement model estimated the direction of movement and taking into account both the vehicle speed and the transmitted from the clutch Torque the estimate the movement direction value is adjusted.

It is thus in a first step by an already fixed mathematical model of motion calculates whether the vehicle is forward or drive backwards or drive. The parameters required for the estimation can partly or completely during be determined during the journey or during vehicle standstill be recorded. The motion model is preferred as a force equation be set up, from which the acceleration of the vehicle estimate lets and thus also the direction of movement of the vehicle, if the initial speed is known.

In a second step is predicted from the force equation Vehicle acceleration and / or direction of motion now with the step selection put in relation. Corresponds to the preferred one selected by the speed dial Vehicle movement direction of the estimated movement direction, so can be assumed that even with higher clutch torques the Vehicle movement direction is maintained and the estimated direction of movement can be equated with the preferred one.

Complies the predicted vehicle movement direction not by the Driving step selection preferred vehicle movement direction, that's how it works Procedure assumes that at higher Clutch moments will reverse the vehicle movement direction. So can preferably by determining the vehicle speed such a direction of movement reversal can be detected. After Reversal of direction of motion preferred by, if only short-term standstill of the vehicle, is excellent, that will Proceed with the current direction of motion as appropriate the preferred vehicle movement direction, already by the gear selection is specified, mark.

Preferably, the vehicle speed is determined at least partially by means of speed sensors. These speed sensors are used for a variety of applications in the vehicle and are often already present in the vehicle. With them, simply the speed of the vehicle can be measured, if the circumference of the wheels is known. By using the speed sensors, the method can detect whether just a reversal of motion has taken place or whether the driving has come to a standstill. Thus, even if the direction of motion predicted by the mathematical model does not coincide with the direction of movement dictated by the gear selection, it can be assumed that if the speed sensors detect a wheel speed substantially equal to zero, this is a reversal of the direction of movement ,

Especially considered the mathematical model of motion is at least partially vehicle-specific Factors. Such factors can the mass of the vehicle, the air resistance of the vehicle, the efficiency etc. be. In addition, you can also other factors, such as the downhill force that results when the vehicle is on an inclined plane, or the slope of the Underground, into which mathematical movement model flow.

In a particular embodiment the sign of the determined direction of movement is at a Zero crossing of the vehicle speed, or the speed changed. One Zero crossing means in doing so, that the corresponding value before and after he receives one from Has zero different value, one or more values of substantially zero. A zero crossing may also be preferred be narrowed down by using values that are different from zero with a substantially negative gradient of one or more Values that are essentially zero are followed to which then again of substantially zero different values, the have a positive gradient.

In particular, the direction of movement of the vehicle can be predicted when starting by means of the mathematical movement model while the vehicle is stationary. Especially when starting or crawling the vehicle, there is often a short-term reversal of direction of movement. So it is possible that when the vehicle has come to a standstill on the slope, the applied clutch torque is not sufficient that the impact force acting on the vehicle is overcome immediately when starting. In such situations, it may happen that the vehicle possibly only briefly in the less preferred direction of travel rolls. If a higher torque is transmitted from the clutch as a result of the rolling back or in the course of the normal control strategy, the drive in the less preferred direction is slowed down and a driving direction reversal occurs. Since this rolling back of the vehicle is perceived by the driver as unpleasant, it is preferred, although variable parameters, such as the downhill force are already known at the beginning of the Ankriechphase and can be correctly recognized by the system, whether an acceleration in the less preferred direction can occur. For this purpose, this estimated acceleration is preferably already calculated during the standstill phase. The necessary parameters can either already exist, such. As the c _w value or they can be determined during the standstill phase, such. B. the weight of the vehicle. Also, parameters, in particular those which are estimated by a vehicle observer, can also be determined during the movement phase before the vehicle is stopped and stored in memory means provided for this purpose, so that they are present when calculating the acceleration or the direction of movement.

Prefers is used in the prediction of the direction of movement by means of the mathematical Movement model takes into account the slope of the ground. Often, a reversal of motion occurs when the vehicle is at a leaning underground stands. The downgrade force either works accelerating on the vehicle or inhibiting, depending on the desired Direction of movement and slope. By considering the slope driving force or slope slope can now give a better estimate of the initial acceleration through the mathematical model and thus also a better prediction the initial one Movement direction can be achieved.

Prefers the slope is determined by at least one vehicle observer. An observer can choose an unmeasured one from different parameters or non-measurable parameters. So can from the acceleration the vehicle the downgrade force acting on the vehicle is obtained become. Such observers are particularly advantageous as they already existing sensors can use to another parameter to obtain.

The invention will now be explained in more detail with reference to the drawings. It shows 1 a schematic representation of the method

First, a vehicle observer determines a predicted acceleration from vehicle-specific and environment-specific values. The predicted acceleration results from the equation

c_w:

Luftwiderstand

A:

Querschnittsfläche

e:

Massenfaktor

f:

Rollwiderstand

i_ges:

Übersetzung

r

Reifenradius

η_ges:

Gesamtwirkungsgrad

können als fahrzeugspezifisch und daher als bekannt angenommen werden. Die Fahrzeugmasse m_Fzg und die Steigung α werden durch einen Fahrzeugbeobachter in der Software geschätzt, solange die Bremse nicht betätigt wird. Das Drehmoment, das von der Kupplung übertragen wird, das Kupplungsmoment M_Kupp ist ebenfalls in der Software bekannt.The vehicle-specific parameters

c _w :

drag

A:

Cross sectional area

e:

mass factor

f:

rolling resistance

i _ges :

translation

r

tire radius

η _ges :

Overall efficiency

can be assumed to be vehicle-specific and therefore known. The vehicle mass m _Fzg and the slope α are estimated by a vehicle _observer in the software, as long as the brake is not applied. The torque transmitted by the clutch, the clutch torque M _Kupp is also known in the software.

When cranking, the braking force F _Brake = 0. The speed-dependent air resistance can be neglected at low speeds, such as when the vehicle creeps. From this follows the equation:

from that surrendered

there all values on the right side are known respectively can through estimated the vehicle observer become. Here are some values, such as the slope of the Underground on which the vehicle is already before, as the vehicle moving estimated and then stored by the vehicle observer.

If there is a risk of rolling back from the equation when ankles creep, ie _if a _{vehicle is} less than zero or less than a negative threshold, it is assumed that the first torque numbers detected by the torque sensors are negative. The wheel speeds, which are then determined and forwarded in the course of Ankriechens or startup of the speed sensors, so are first interpreted as a reverse drive and thus accordingly, such. B. with a positive or negative sign characterized.

If the danger arises from the equation when the car rolls forward, for example because it is on a downhill _slope , ie _if a _{vehicle is} greater than zero or greater than a positive threshold, it is assumed that the first Speeds, the driven wheels are positive and the speeds which are determined by the Drehzahlsen sensors are marked accordingly, for example by providing them with a positive sign.

If it is clear from the mathematical motion model that the vehicle is not being accelerated in any direction, since the initial clutch torque M _{Kupp is} too small and no appreciable gradient of the ground has been determined, then the sign of the corresponding rotational speeds during movement of the vehicle is selected according to the gear selection.

If, for example, a further torque build-up results from a vehicle control on the clutch, a distinction is now made as to which drive _{step has} been selected and which initial values for the vehicle _acceleration a _vehicle are present. If the driving position D was selected, for example by the driver, then there is a high probability that the equation of motion _will provide positive vehicle _{acceleration values} a _Fzg at higher clutch _torques . If the first vehicle _{acceleration values} were negative and the higher clutch _torques are now the vehicle _{acceleration values} a _Fzg , so, as soon as the speeds reach zero or make a zero crossing, a change of sign of the speeds made from negative to positive.

If the selected gear R, that is the preferred vehicle traveling direction is negative, so there is a high probability that at a higher, transmitted by the clutch torque than the originally viewed M _Kupp the vehicle movement is negative. If the originally predicted vehicle _acceleration a _{Fzg is} positive, it is assumed that the next zero _{pass of} the rotational speed values, ie if the rotational speed values drop from a non-zero value to substantially zero and then increase again, the rotational speed values following the zero pass are negative, ie in the direction of the preferred vehicle movement direction.

Claims (9)

Method for detecting the direction of movement of a vehicle, wherein the vehicle speed is detected and the direction of movement is predicted by means of a mathematical movement model, characterized in that the torque transmitted by a vehicle clutch is detected and taking into account both the vehicle speed and the torque transmitted by the clutch Forecasting the direction of movement is adjusted. Method according to the preceding claim, characterized characterized in that the vehicle speed is at least partially is determined by means of speed sensors. Method according to the preceding claims, characterized characterized in that the mathematical motion model is vehicle-specific Factors taken into account. Method according to one of the preceding claims, characterized characterized in that at a zero crossing of the vehicle speed the predicted direction of movement is changed in its sign. Method according to the preceding claim, characterized characterized in that the zero crossing of the vehicle speed considering of the transferred Clutch torque for changing the Direction sign is used. Method according to one of the preceding claims, characterized characterized in that the direction of movement of the vehicle before and / or while the startup by means of the mathematical motion model predicts becomes. Method according to one of the preceding claims, characterized characterized in that in the prognosis of the direction of movement means of the mathematical model of motion takes into account the slope of the ground becomes. Method according to the preceding claim, characterized characterized in that the slope by at least one vehicle observer is determined. Method according to one of the preceding claims, characterized characterized in that the slope by means of at least one acceleration sensor is determined.