Methods, apparatus and computer program products for determining the vertical speed of an aircraft
First Claim
1. A method for determining vertical speed of an aircraft comprising:
- determining a first vertical velocity of the aircraft based upon a pressure altitude value associated with the aircraft;
obtaining a second vertical velocity of the aircraft from a global positioning system (GPS) receiver carried by the aircraft; and
combining the first and second vertical velocities to determine the vertical speed of the aircraft in a manner independent of signals provided by an air data computer (ADC), an inertial reference system (IRS) and an inertial navigation system (INS).
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Accused Products
Abstract
A method, an apparatus and a computer program product are provided for accurately determining the vertical speed of an aircraft in a manner independent of signals provided by an air data computer, an inertial reference system and an inertial navigation system. Initially, a first vertical velocity of the aircraft is determined based upon a pressure altitude value associated with the aircraft. A second vertical velocity of the aircraft is also obtained from a GPS receiver carried by the aircraft. The first and second vertical velocities are then combined to determine the vertical speed of the aircraft. In this regard, the first and second vertical velocities are combined by complimentarily filtering the first and second vertical velocities. More particularly, the first vertical velocity is typically low pass filtered to remove high frequency noise that is attributable to the relatively low resolution of the first vertical velocity value. Additionally, the second vertical velocity is typically high pass filtered to reduce errors due to long-term drift. Thus, the vertical speed of the aircraft is determined according to the present invention so as to have the best attributes of both the first and second vertical velocity values while eliminating the most common types of errors included within the first and second vertical velocity values.
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Citations
30 Claims
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1. A method for determining vertical speed of an aircraft comprising:
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determining a first vertical velocity of the aircraft based upon a pressure altitude value associated with the aircraft;
obtaining a second vertical velocity of the aircraft from a global positioning system (GPS) receiver carried by the aircraft; and
combining the first and second vertical velocities to determine the vertical speed of the aircraft in a manner independent of signals provided by an air data computer (ADC), an inertial reference system (IRS) and an inertial navigation system (INS). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
receiving a series of altitude values from the GPS receiver over time; and
determining a rate of change of the altitude values provided by the GPS receiver.
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7. A method according to claim 6 wherein obtaining the second vertical velocity of the aircraft further comprises low pass filtering the rate of change of the altitude values provided by the GPS receiver.
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8. A method according to claim 1 wherein obtaining the second vertical velocity of the aircraft comprises receiving the second vertical velocity of the aircraft from the GPS receiver.
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9. A method according to claim 1 wherein obtaining the second vertical velocity of the aircraft comprises repeatedly obtaining values for the second vertical velocity of the aircraft over time, and wherein the method further comprises:
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determining if at least a predetermined number of satellites are in view of the GPS receiver; and
maintaining the second vertical velocity equal to a prior value of the second vertical velocity if less than the predetermined number of satellites are in view of the GPS receiver.
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10. A method according to claim 9 further comprising providing a signal to indicate that the vertical speed is unreliable if less than the predetermined number of satellites are in view of the GPS receiver for a continuous period that is at least as great as a predetermined time.
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11. An apparatus for determining vertical speed of an aircraft comprising:
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a processor for determining a first vertical velocity of the aircraft based upon a pressure altitude value associated with the aircraft, and for obtaining a second vertical velocity of the aircraft from a global positioning system (GPS) receiver carried by the aircraft, wherein said processor is adapted to combine the first and second vertical velocities to determine the vertical speed of the aircraft in a manner independent of signals provided by an air data computer (ADC), an inertial reference system (IRS) and an inertial navigation system (INS). - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A computer program product for determining vertical speed of an aircraft, wherein the computer program product comprises a computer readable storage medium having computer readable program code means embodied therein, said computer readable program code means comprising:
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first computer instruction means for determining a first vertical velocity of the aircraft based upon a pressure altitude value associated with the aircraft;
second computer instruction means for obtaining a second vertical velocity of the aircraft from a global positioning system (GPS) receiver carried by the aircraft; and
third computer instruction means for combining the first and second vertical velocities to determine the vertical speed of the aircraft in a manner independent of signals provided by an air data computer (ADC), an inertial reference system (IRS) and an inertial navigation system (INS). - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
fourth computer instruction means for determining if at least a predetermined number of satellites are in view of the GPS receiver; and
fifth computer instruction means for maintaining the second vertical velocity equal to a prior value of the second vertical velocity if less than the predetermined number of satellites are in view of the GPS receiver.
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30. A computer program product according to claim 29 further comprising sixth computer instruction means for providing a signal to indicate that the vertical speed is unreliable if less than the predetermined number of satellites are in view of the GPS receiver for a continuous period that is at least as great as a predetermined time.
Specification