Device and method for detecting and preprocessing weights acting on a vehicle seat
First Claim
1. A device for detecting and evaluating weight exerted by a person sitting on a vehicle seat, the device comprisingat 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, the function for the automatic drift correction comprising a discriminator for differentiating drift in the weighing-signal from low loads of a limited time; and
the evaluation circuit comprising a function for a long term recording mode, wherein the evaluation circuit includes a data memory for storing over a predetermined sliding time period weighing signals, output signals and/or other signals and, in addition, records in an associated memory area of the data memory time signals correlating to the weighing signals, output signals and/or other signals.
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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.
28 Citations
28 Claims
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1. A device for detecting and evaluating weight exerted by a person sitting on a vehicle seat, 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, the function for the automatic drift correction comprising a discriminator for differentiating drift in the weighing-signal from low loads of a limited time; and
the evaluation circuit comprising a function for a long term recording mode, wherein the evaluation circuit includes a data memory for storing over a predetermined sliding time period weighing signals, output signals and/or other signals and, in addition, records in an associated memory area of the data memory time signals correlating to the weighing signals, output signals and/or other signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for detecting and preprocessing weights acting on a vehicle seat for determining the mass of an occupant sitting on 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 position correlating to them;
calculating the mass of the occupant from the absolute overall weighing signal and the mass correction value;
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;
calculating a difference D=WN−
WL being formed and checking it whether it lies within a predetermined range of zero drift values;
adding this difference to a value stored in a difference-value memory in the case in which the difference D lies within the predetermined range; or, in the case in which the difference D lies outside the predetermined range, the value stored in the difference-value memory is kept constant; and
wherein in a long-term recording mode, the evaluation circuit records in an area of a data memory for a predetermined sliding time period weighing signals, output signals and/or other signals and, in addition, records in an associated area of the data memory time signals correlating to the weighing signals, output signals and/or other signals. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. 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 a least three load cells disposed on load-carrying parts of the vehicle seat;
forming from the weighing signals an absolute overall weighing signal, which corresponds to the weight exerted on the seat by the mass of the occupant;
determining from the weighing signals the position of the center of gravity of the weight exerted on the sitting area by the mass of the occupant;
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 position correlating to them;
calculating the mass of the occupant from the absolute overall weighing signal and the mass correction value;
correcting of 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;
calculating a difference D=WN−
WL being formed and checking it whether it lies within a predetermined range of zero drift values;adding this difference to a value stored in a difference-value memory in the case in which the difference D lies within the predetermined range; or discarding this difference and storing a constant value in the difference-value memory in the case in which the difference D lies outside the predetermined range; and wherein, taking into account the summated values of the weighing signals, changes over time of the weighing signals of the load cells are used to differentiate whether a weight is exerted on the vehicle seat by a living person or an inanimate object, and wherein, depending on this differentiation, an output signal is generated.
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28. Device for detecting and evaluating a weight exerted by a person sitting on a vehicle seat, comprising
at least three load cells, which are disposed on load-carrying parts of the vehicle seat 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, the evaluation circuit comprising a function for automatic zero-drift correction of the weighing signal, the function for the automatic drift correction comprising a discriminator for differentiating the weighing-signal drift from low loads of a limited time and a differentiating function, which differentiates on the basis of the changes over time of the weighing signals of the load cells between weights which are exerted on the vehicle seat by actual persons on the one hand an inanimate objects on the other hand, and supplies a corresponding output signal.
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Specification