Patent EP-2610782-A1 (EP)
Inventor: MORTARA PIETRO
IPC: G01C21/28
Filed: 2012-12-27
Abstract: Method for planning the route of a vehicle, said route comprising a plurality of successive road segments, the method comprising the steps of: 
- providing a control unit (1) comprising an electronic horizon (2) including vehicle data (4) representing the vehicle and Traffic Sign Recognition data (6) representing objects which are present at the side of the road on which the vehicle is travelling, and which are automatically recognized by a TSR system of the vehicle; 
- providing a graphic interface, connected to the control unit (1), by means of which a starting point and an arrival point of said route are defined; 
- providing, within the control unit (1), a processing module (8) adapted to process the data of the electronic horizon (2), combining them with cartographic data from a map (10) connected to the control unit (1), thus obtaining processed data which represent the spatiotemporal position of the vehicle; 
- providing, within the control unit (1), a weight modification module (12), connected to the processing module (8), and adapted to assign to each road segment a predetermined cost function based on said processed data; 
- providing, within the control unit (1), a route planning module (16), connected to the weight modification module (12), and adapted to plan the route on the basis of said cost function, the starting and arrival points of the route, and the cartographic data; 
 
the method being characterized in that: 
- the electronic horizon (2) includes surrounding vehicle data (18) representing vehicles located within a predetermined distance from the vehicle, and infrastructure data (20) representing the road conditions of geographic areas of predetermined dimensions located around the route to be planned; 
- the data processing step comprises the replacement of a data element present in the electronic horizon (2) with a new data element acquired from the control unit (1) in a successive instant of time, or the calculation of the weighted mean of the data of the electronic horizon (2) by combining them with new data acquired from the control unit (1); 
 
in which the calculation of the weighted mean comprises the steps of: 
- assigning to each data element of the electronic horizon (2) and to each new data element acquired from the control unit (1) a reliability coefficient (ω), a standard deviation (σ), a first time factor (TL) indicating the time interval within which the data element is valid, and a second time factor (TF) indicating the speed of aging of the data element; 
- calculating the weighted mean, thus obtaining a weighted data element, by means of the following equations:        x         =           Σ     i   =   1     N             σ   i     *   λ       σ   2       *     x   i             Σ     i   =   1     N             σ   i     *   λ       σ   2                     λ   =     {             1   -         t   1     -     τ   0       TL       TF               t   1     -     t   0     <   TL         t   1     -     t   0     >   TL               0                         
where x is the data element, λ is a variable which indicates the time decay and t0 and t1 indicate two successive instants of acquisition.