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AssigneeRockwell International Corporation
InventorJaime B. Colley
Estimating the term…
A method of smoothing Kalman Filter position states forming a "groundtrack" in a receiver used in a satellite based positioning system (e.g. GPS). In such systems, data pairs including an incoming value and a "raw" reliability estimate (e.g. a standard deviation) are normally fed directly to the Kalman Filter. The Kalman Filter computes the resultant and an overall uncertainty estimate by applying a "weight" to each successive incoming value based on its reliability. The Kalman Filter also estimates incoming values based on past values. The method involves the unique steps of replacing the raw reliability with a "modified" reliability if the incoming value is too far from the estimate in view of an adjustable limit envelope defined by the current uncertainty estimate and reliability value. If the difference between what we get and what we expect is small, then the reliability value is passed without modification. If the difference is large, however, then we decrease the reliability value to tell the Kalman Filter that the value is less reliable. In other words, we "de-weight" implausible values. The modified reliability value is preferably scaled or decreased in proportion to the amount by which the square of the incoming value is outside of the limit envelope. This even minimizes the effect of values that are very strong (have high "reliability"), but still very wrong, and thereby smoothes the resultants produced by the Kalman Filter.
A method of smoothing discontinuities in a series of resultant states in a system of the type that uses a Kalman Filter to statistically derive the resultant states along with corresponding uncertainty estimates based on a succession of incoming data pairs comprising measurement values and corresponding reliability estimates which the Kalman Filter uses in order to establish a weight for the measurement value, the method comprising the steps of:
The method of claim I wherein the resultant states are velocity estimates in a satellite based positioning system.
A method of smoothing discontinuities in a series of resultant states in a satellite based positioning system that uses a Kalman Filter to statistically derive the resultant states along with corresponding uncertainty estimates based on a succession of incoming data pairs comprising pseudoranges and corresponding reliability estimates which the Kalman Filter uses in order to establish a weight for the pseudoranges, the method comprising the steps of:
An improved satellite based positioning system receiver having a Kalman Filter that statistically derives a succession of position states along with corresponding uncertainty estimates based on a succession of incoming pseudoranges and corresponding reliability estimates which the Kalman Filter uses in order to establish a weight for the pseudoranges, the improvement comprising:
A method of smoothing discontinuities in position estimate solutions in a satellite positioning system (SATPS) receiver that receives a plurality of SATPS signals from a plurality of satellites and uses a Kalman Filter to update a current position estimate (x y z), the method comprising the steps of:
Dependencies are inferred from the claim text.