Device and method for detecting and preprocessing weights acting on a vehicle seat
First Claim
1. A device for detecting and evaluating a weight exerted by a person sitting on a vehicle seat, the vehicle seat comprising load carrying parts, the device comprising at least three load cells, said load cells being non-linearly disposed and spaced apart and disposed on said load-carrying parts of the vehicle seat, said load cells each generating a weighing signal corresponding to the weight;
- and an electronic evaluation circuit, adapted to receive and preprocess the weighing signals of the load cells and generate an output signal based on the weighing signals, the evaluation circuit comprising an evaluation function with which a localization of the center of gravity of the weight acting on the vehicle seat can be carried out from the individual weighing signals of the at least three load cells, and the evaluation circuit comprising a correction function, with which force bypasses can be taken into account in the forming of the output signal, the evaluation circuit comprising a function for automatic zero-drift correction of the weighing signal, and the function for the automatic drift correction comprising a discriminator for differentiating drift in the weighing-signal from low loads of a limited time.
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Accused Products
Abstract
In order to form a device for detecting and preprocessing weights acting on a vehicle seat in such a way that it can be used in particular in conditions which are very difficult in terms of measuring technology, and in particular under the other special ambient conditions within a vehicle, and the weighing signal of which is substantially uninfluenced by this and can consequently provide a reliable parameter for airbag activation, it is proposed that this device comprises at least three load cells, which are disposed on load-carrying parts of the vehicle seat at corner points of an imaginary polygonal area and in each case generate a weighing signal corresponding to the weight, and an electronic evaluation circuit, which receives and preprocesses the weighing signals of the load cells and generates an output signal based on the weighing signals, the evaluation circuit comprising an evaluation function with which a localization of the center of gravity of the weight acting on the vehicle seat can be carried out from the individual weighing signals of the at least three load cells, and the evaluation circuit comprising a correction function, with which force bypasses can be taken into account in the forming of the output signal.
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Citations
30 Claims
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1. A device for detecting and evaluating a weight exerted by a person sitting on a vehicle seat, the vehicle seat comprising load carrying parts, the device comprising
at least three load cells, said load cells being non-linearly disposed and spaced apart and disposed on said load-carrying parts of the vehicle seat, said load cells each generating a weighing signal corresponding to the weight; - and
an electronic evaluation circuit, adapted to receive and preprocess the weighing signals of the load cells and generate an output signal based on the weighing signals, the evaluation circuit comprising an evaluation function with which a localization of the center of gravity of the weight acting on the vehicle seat can be carried out from the individual weighing signals of the at least three load cells, and the evaluation circuit comprising a correction function, with which force bypasses can be taken into account in the forming of the output signal, the evaluation circuit comprising a function for automatic zero-drift correction of the weighing signal, and the function for the automatic drift correction comprising a discriminator for differentiating drift in the weighing-signal from low loads of a limited time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for detecting and preprocessing weights acting on a vehicle seat for determining the mass of an occupant sitting on a sitting area of the vehicle seat, comprising the steps of:
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detecting by means of an electronic evaluation circuit weighing signals of at least three load cells disposed on non-linearly disposed, spaced, load-carrying parts of the vehicle seat;
forming an absolute overall weighing signal from the weighing signals, the absolute overall weighing signal corresponding to the weight exerted on the seat by the mass of the occupant;
determining the position of the center of gravity of the weight exerted on the sitting area by the mass of the occupant from the weighing signals;
correlating the absolute overall weighing signal with the position of the center of gravity, with a correction parameter being determined;
calling up a mass correction value for the correction of force bypasses in dependence on the correction parameter from a data memory which contains stored mass correction values for absolute overall weighing signals and center-of-gravity positions correlating to them; and
calculating the mass of the occupant from the absolute overall weighing signal and the mass correction value; and
correcting the zero point of the weighing signals on the basis of weighing signals of the load cells with the vehicle seat unloaded;
the zero-point correction being performed by storing for each load cell a last-valid weighing signal WL with the vehicle seat unloaded and comparing this with the weighing signal WN of the subsequently valid measurement with the seat unloaded;
by a difference D=WN−
WL being formed and it then being checked whether this lies within a predetermined range of zero drift values;
by this difference being added to a value stored in a difference-value memory in the case in which the difference D lies within the predetermined range;
and by this difference being discarded and the value stored in the difference-value memory kept constant in the case in which the difference D lies outside the predetermined range. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification