Boots – shoes – and leggings
Patent
1989-12-26
1991-06-11
Black, Thomas G.
Boots, shoes, and leggings
364447, 340995, G06F 1550
Patent
active
050237985
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method of and apparatus for determining a position of a land vehicle wherein a position determined from driving data is corrected in accordance with control data stored in a memory.
A system has been developed (Electronic Traffic Pilot for Automobile Drivers) which gives recommendations for an optimal driving route on the basis of the existing road network, the instantaneous position of the vehicle, and the origin and destination data. The reliability of this system depends among other things on the accuracy with which the instantaneous position of the vehicle can be determined.
Method and apparatuses for determining the position of a land vehicle which determine and evaluate only driving data such as travel distances and driving direction by using principles of dead reckoning position finding suffer from a loss of location after longer driving distances, which can lead to an erroneous recommendation. By repeated correction in the form of matching with data of a stored, digitized road network, this loss of location can be kept within limits such that the reliability of the recommendation is not impaired. However, in carrying out the matching, problems can occur which are based e.g. on the density of the road network, the limited memory space of the computer arrangement present in the vehicle, or the computing time required by the computer.
If the road network is very dense and the matching is carried out only at long intervals of space and time due to the required computing time, the position finding inaccuracy can accumulate in the meantime to the extent that the position determined from the driving data is indeed to be assigned to the road network, but this road network deviates from the actual position, and the matching is then made to the wrong street. It is not desirable to limit to a thinned out road network, since the system is required to issue recommendations between optional positions of origin and destination. Accordingly, it must be possible to take into account a region in the order of magnitude of a federal state or of the entire federal territory of the Federal Republic of Germany.
SUMMARY OF THE INVENTION
The object of the invention is a method of and an apparatus for determining the position of a land vehicle in such a way that a reliable and rapid matching of the position calculated from the driving data with the road network is made possible even with extensive, detailed road networks.
This object is achieved by subdividing a digitized road network in a plurality of meshes defined according to a surface area by covering the road network with a grid. Instantaneous vehicle positions are defined by respective meshes which are selected one after another beginning from a starting position. The position calculated from the driving data is corrected at predetermined intervals to a possible and most probable position in a respective selected mesh and a proximate area.
The invention is based on the understanding that the loss of location in the evaluation of driving data only accumulates gradually as the traveled distance increases and can, therefore, be kept within limits with rapid successive corrections. Consequently also, only the roads located in the vicinity of the calculated position play a role in the matching. Since the relevant roads change continuously while driving through the road network, a criterion is needed for choosing the roads which are to be utilized for the matching.
The invention provides this criterion by covering the digitized road network with a grid, so that the road network is now broken up into meshes and it can be unequivocally defined whether or not roads lie within the relevant region. But in order to be able to carry out an effective matching also when passing from one mesh to the other, the relevant region is not defined by a single mesh. Rather, that mesh within which the position calculated from the driving data is located is made into the center field of a larger region in which the roads are likewise
REFERENCES:
patent: 4796191 (1989-01-01), Honey et al.
patent: 4897792 (1990-01-01), Hosoi
patent: 4924402 (1990-05-01), Ando et al.
patent: 4937572 (1990-06-01), Yamada et al.
"Car-Guide-on-Board Computer for Automobiles", 1984, pp. 697-706, National Computer Conference, 364/449.
Neukirchner Ernst-Peter
Schlogl Dietmar
Black Thomas G.
Robert & Bosch GmbH
Striker Michael J.
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