DE102005008974A1 - Estimation of coordinates of object using velocity model, for pedestrian protection system, involves determining vehicle velocity and acceleration for second-order velocity model - Google Patents

Abstract

Estimation of coordinates of object using velocity model involves using a second-order velocity model, for which a vehicle velocity and a vehicle acceleration are determined. Vehicle velocity is supplied by a vehicle bus system, and vehicle acceleration is estimated from the vehicle velocity or measured by an acceleration sensor and read via the vehicle bus. The relative velocity of the second-order velocity model may be split into the individual components vehicle velocity and object velocity.

Description

The The invention is based on a method for estimating object coordinates after the genus of the independent Patent claim 1.

Known systems for sensing a vehicle environment have the goal of tracking objects, ie the determination of the time profile of 1-, 2- or 3-dimensional object coordinates. The track algorithms used are usually based on so-called hypotheses, ie on estimated or predicted object coordinates for the next measurement cycle. To estimate these object coordinates in the next cycle, a so-called velocity model is used. Here one differentiates models of different order in the time t. A first order system is determined by equation (1). S (T) = V rel · T (1)

A second order system is determined by equation (2). s (T) = v rel · T + 0.5 · a rel · t 2 (2)

The parameters relative speed v _rel and relative acceleration a _rel necessary for calculating the object trajectory s _(t) are generally unknown and are estimated from measured data. In order to ensure a stable algorithm, first-order speed models are chosen in known systems, in which only one parameter has to be estimated.

Advantages of invention

The inventive method to appreciate of object coordinates with the features of the independent patent claim has in contrast the advantage of that by taking into account the vehicle speed and the vehicle acceleration an improved Speed model can be used, so that braking operations of the Vehicle in estimation the object coordinates can be. This results in more precise hypotheses or estimates of the object coordinates thus enabling improved tracking of objects. this leads to especially in the context of pedestrian protection in real situations, such as during a heavy braking event in a sudden Emergence of a pedestrian in the Field of view of the driver, to a more robust tracking algorithm, i.e. to a more robust object tracking.

The inventive method allows by using the second-order rate model advantageously tracking the objects even in one strong deceleration of the vehicle, since the speed model is second Order in contrast to a first-order speed model can also consider strong relative accelerations.

By those in the dependent Claims listed measures and further developments are advantageous improvements of the independent claim specified method of estimation possible from object coordinates.

Especially advantageous that the vehicle speed of a vehicle bus system, z. B. a CAN bus system is provided. Because the current vehicle speed constantly on the vehicle bus system to disposal is set, the vehicle speed can be in more advantageous Mode at any time from a corresponding bus interface become.

The associated Vehicle acceleration can advantageously simple and fast estimated from the vehicle speed.

alternative can the vehicle acceleration advantageously with a Accelerometer be measured, the accelerometer Part of the pedestrian protection system or another system, such as a crash sensor. If the accelerometer is part of another system, then the acceleration information the method of the invention for example about the vehicle bus available posed.

The inventive method decomposes the relative velocity of the velocity model second Order into the individual components vehicle speed and object speed, the vehicle speed, as already stated, can be easily read from a bus interface.

Farther decomposes the method according to the invention the relative acceleration of the second-order velocity model into the individual components vehicle acceleration and object acceleration.

Since the object speed and the object acceleration can be neglected in slow and thus also slowly accelerated objects, the relationship (4) is used for the speed model, whereby an improved speed mensis due to the already described reading of the vehicle speed and the calculated vehicle acceleration Second order order for the estimation of the object coordinates is provided. S (T) ≈ v rel · T + 0.5 · a vehicle · t 2 ≈ (v obj - v vehicle ) · T + 0.5 · (Δv vehicle / At) · t 2 (4)

For standing Objects and moving vehicles is the approximation of the context (4) exactly, for slow objects results from the context (4) a very good approximation.

The Object speed and object acceleration may be during the Tracking process estimated become. The advantage of the invention lies in the fact that by the decomposition of the relative speed in vehicle speed and object speed and the relative acceleration in vehicle acceleration and object acceleration the object velocity to be estimated and object acceleration opposite the vehicle speed and the vehicle acceleration comparatively are small, so the algorithm becomes more robust.

The inventive method to appreciate of object coordinates can be improved especially in pedestrian protection systems the triggering algorithms be used.

drawing

embodiments The invention are illustrated in the drawings and in the following description explained.

It demonstrate

1 a flowchart of a first embodiment of a method for estimating object coordinates,

2 a flowchart of a second embodiment of a method for estimating object coordinates, and

3 a flowchart of a third embodiment of a method for estimating object coordinates.

description

Known Lead systems for sensing a vehicle environment, an estimate of the object coordinates through, where for this estimate a so-called speed model is used. To one to ensure stable algorithm used in known systems first order speed models, where only one parameter needs to be estimated, since in the Usually neither the relative speed nor the relative acceleration are known.

According to the invention is a Procedure for estimation the object coordinates proposed, which is a speed model used second-order, for which is a vehicle speed and a vehicle acceleration be determined. The vehicle acceleration can be determined from the Estimated vehicle speed or measured with an accelerometer. The acceleration sensor can be part of an associated Pedestrian protection system or another system. Is the acceleration sensor part of a other system, then the acceleration information about one Vehicle bus available posed.

How out 1 is seen, the inventive method for estimating object coordinates according to the first embodiment after the start in the step reads 100 the vehicle speed v _vehicle from a bus interface, for example, a CAN bus interface. In step 200 is calculated from a change in the vehicle speed v _vehicle, the vehicle acceleration a _vehicle according to the equation (3). a vehicle - Δv vehicle / Δt (3) calculated.

In step 300 the object trajectory s _(t ) is estimated according to the context (4). s (T) ≈ v rel · T + 0.5 · a vehicle · t 2 ≈ (v obj - v vehicle ) · T + 0.5 · (Δv vehicle / T) * t 2 (4)

The relationship (4) takes account of braking processes of the vehicle and provides an exact approximation of the object trajectory s _(t) for stationary objects and moving vehicles. For slow and thus slowly accelerated objects a very good approximation of the object trajectory s _{(t) is} provided. Thus, by exploiting the knowledge of the vehicle speed via the bus interface, it is easy to take into account the braking action of the vehicle in the crash situation with a pedestrian and thus for the triggering algorithm of pedestrian protection devices.

As can be seen from the relationship (4), the relative velocity v _rel of the velocity model of the second order in the individual components of vehicle speed v _vehicle and _the object velocity v _Obj disassembled and the relative acceleration a _rel of the second-order rate model is in the individual components of the vehicle acceleration a _vehicle and Objektbeschleuni decomposed, wherein the object acceleration in the estimation of the object trajectory s _{(t) is} neglected.

How out 2 is apparent, is in the second embodiment of the method according to the invention for the estimation of object coordinates in contrast to the first embodiment 1 the vehicle acceleration a _{vehicle is} not estimated from the vehicle speed, but in step 210 read directly from an accelerometer, which is part of the pedestrian protection system.

How out 3 is seen in the third embodiment of the method according to the invention for the estimation of object coordinates in contrast to the step 210 in the second embodiment 2 the vehicle acceleration a _vehicle in the step 220 not read from an acceleration sensor but from a bus interface, ie the acceleration sensor is part of another system, eg. As a crash sensor, and provides the acceleration information on the vehicle bus system, z. As a CAN bus system available.

Claims (9)

A method of estimating object coordinates using a speed model, characterized in that a second order speed model is used for which a vehicle speed (v _vehicle ) and a vehicle acceleration (a _vehicle ) are determined. A method according to claim 1, characterized in that the vehicle speed (v _vehicle ) is provided by a vehicle bus system. A method according to claim 1 or 2, characterized in that the vehicle acceleration (a _vehicle) from the vehicle speed (v _vehicle) is estimated. A method according to claim 1 or 2, characterized in that the vehicle acceleration (a _vehicle ) is measured by an acceleration sensor. A method according to claim 4, characterized in that the measured with the acceleration sensor vehicle acceleration (a _vehicle ) is read out via the vehicle bus. Method according to one of Claims 1 to 5, characterized in that the relative speed (v _rel ) of the second-order speed model is decomposed into the individual components vehicle speed (v _vehicle ) and object speed (v _Obj ). Method according to one of claims 1 to 6, characterized in that the relative acceleration of the second-order speed model is decomposed into the individual components vehicle acceleration (a _vehicle ) and object acceleration. Method according to one of claims 1 to 7, characterized in that for the speed model of the context S (T) ≈ v rel · T + 0.5 · a vehicle · t 2 ≈ (v obj - v vehicle ) · T + 0.5 · (v vehicle / At) · t 2 where v _{rel is} the relative velocity, a _{vehicle is} the vehicle _acceleration , v _{obj is} the object speed, and v is the _vehicle speed. Pedestrian protection system, which to treasure of object coordinates, the method according to one of claims 1 to 8 used.