Signal selection apparatus for redundant signal sources
First Claim
1. Signal selection apparatus for supplying an output signal derived from a plurality of redundant signals supplied by a plurality of signal sources, each of said redundant signals representing substantially identical information with one of said signal sources being a precision signal source supplying more precise signal information than the remaining ones of said signal sources, said signal selection apparatus comprising:
- signal selection means responsive to a signal source failure signal associated with each of said signal sources, each of said signal source failure signals indicating when the signal source associated therewith is operational and indicating when the signal source associated therewith operates in a failure state, said signal source selection means further responsive to said plurality of redundant signals, said signal source selection means including logic means for comparing said more precise signal supplied by said precision signal source with the signals supplied by the remaining signal sources, said logic means including means for supplying a first selection signal having a first predetermined value when the magnitude of said more precise signal exceeds the magnitude of each of the redundant signals supplied by said remaining signal sources by a first predetermined amount and having a second predetermined value when the magnitude of said more precise signal does not exceed the magnitude of each of said redundant signals supplied by said remaining signal sources by said first predetermined amount, said logic means further including means for supplying a second selection signal when said first selection signal is of said second predetermined value and said failure signal associated with said precision signal source indicates said precision signal source is operational; and
signal consolidation means responsive to said redundant signals and responsive to said first and second selection signals for supplying said output signal, said signal consolidation means including means for supplying said more precise signal as said output signal when said signal selection means supplies said second selection signal, said signal consolidation means including means responsive to said signal source failure signal associated with said precision signal source for supplying said output signal as a mathematically weighted average of said signals supplied by said remaining signal sources whenever said signal source failure signal associated with said precision signal source indicates said precision signal source is operating in said failure state, said signal consolidation means further including means responsive to said first selection signal for supplying said output signal as a mathematically weighted average of at least said signals supplied by said remaining signal sources whenever said first selection signal is said first predetermined value.
0 Assignments
0 Petitions
Accused Products
Abstract
Apparatus for signal selection and signal consolidation of the redundant sensor signals in a triply redundant control system wherein one of the redundant sensors supplies precise information and the remaining two sensors supply less precise information is disclosed. Signal selection is based on the operational state of the three sensors, with the signal provided by the precision sensor being selected whenever the precision sensor is operational. If the precision sensor fails, each channel is supplied with a signal that is a weighted average of the signals supplied by the two less accurate sensors. In some arrangements of the invention whenever the precision sensor has not failed, but supplies a signal that deviates substantially from the signals being supplied by the two less accurate sensors, the signal supplied to each channel of the control system is a weighted average of all three sensor signals. In other arrangements of the invention, a weighted average of the signals supplied by the two less precise sensors is provided whenever the precision sensor fails and whenever the precision sensor has not failed, but supplies a signal that deviates substantially from the signals being supplied by the two less accurate sensors. To prevent abrupt variations in the signal supplied to the control system, the signal supplied by the signal selection apparatus smoothly transists from the signal being supplied at the time a particular failure condition occurs to the signal to be supplied following that failure.
59 Citations
16 Claims
-
1. Signal selection apparatus for supplying an output signal derived from a plurality of redundant signals supplied by a plurality of signal sources, each of said redundant signals representing substantially identical information with one of said signal sources being a precision signal source supplying more precise signal information than the remaining ones of said signal sources, said signal selection apparatus comprising:
-
signal selection means responsive to a signal source failure signal associated with each of said signal sources, each of said signal source failure signals indicating when the signal source associated therewith is operational and indicating when the signal source associated therewith operates in a failure state, said signal source selection means further responsive to said plurality of redundant signals, said signal source selection means including logic means for comparing said more precise signal supplied by said precision signal source with the signals supplied by the remaining signal sources, said logic means including means for supplying a first selection signal having a first predetermined value when the magnitude of said more precise signal exceeds the magnitude of each of the redundant signals supplied by said remaining signal sources by a first predetermined amount and having a second predetermined value when the magnitude of said more precise signal does not exceed the magnitude of each of said redundant signals supplied by said remaining signal sources by said first predetermined amount, said logic means further including means for supplying a second selection signal when said first selection signal is of said second predetermined value and said failure signal associated with said precision signal source indicates said precision signal source is operational; and signal consolidation means responsive to said redundant signals and responsive to said first and second selection signals for supplying said output signal, said signal consolidation means including means for supplying said more precise signal as said output signal when said signal selection means supplies said second selection signal, said signal consolidation means including means responsive to said signal source failure signal associated with said precision signal source for supplying said output signal as a mathematically weighted average of said signals supplied by said remaining signal sources whenever said signal source failure signal associated with said precision signal source indicates said precision signal source is operating in said failure state, said signal consolidation means further including means responsive to said first selection signal for supplying said output signal as a mathematically weighted average of at least said signals supplied by said remaining signal sources whenever said first selection signal is said first predetermined value. - View Dependent Claims (2, 3, 4)
-
-
5. Signal selection apparatus for supplying an output signal derived from a plurality of redundant input signals, each of said redundant input signals being supplied by a signal source with one of said signal sources supplying a more precise signal than the remaining ones of said signal sources, said signal selection apparatus comprising:
-
detection means responsive to said redundant signals for supplying signal source failure signals associated with each of said redundant signal sources, said signal source failure signals being representative of the operational state of each of said signal sources to indicate when each of said signal sources fails to provide a reliable signal and to indicate when each of said signal sources provides a reliable signal; signal selection logic means responsive to said signal source failure signals and responsive to said redundant signals for supplying at least a first and second signal selection signal, said signal selection logic means including comparator means for comparing said more precise signal with each of the remaining redundant signals supplied by said remaining signal sources, said comparator means including means for supplying said first signal selection signal when the magnitude of said more precise signal exceeds the magnitude of each of said remaining redundant signals by at least a predetermined threshold value, said signal selection logic means further including means for supplying said second signal selection signal when said signal source failure signal associated with the signal source supplying said more precise signal indicates said more precise signal source supplies a reliable signal and said first selection signal is not supplied by said comparator means; and signal consolidation means responsive to said redundant signals supplied by said signal sources and responsive to said first and second signal selection signals for supplying said output signal derived from said redundant input signals, said signal consolidation means including first signal means for supplying said more precise signal as said output signal whenever said signal selection logic means supplies said second signal selection signal, said signal consolidation means including second signal means for supplying said output signal as a mathematically weighted average of said remaining redundant signals supplied by said signal sources other than the more precise signal source during periods of time when the failure signal associated with said more precise signal source indicates that said more precise signal source is not reliable, said signal consolidation means further including third signal means for supplying said output signal as a mathematically weighted average of at least said remaining redundant signals whenever said signal selection means supplies said first signal selection signal to indicate said more precise signal exceeds each of said remaining signals by at least said first predetermined threshold value. - View Dependent Claims (6, 7, 8, 9)
-
-
10. Signal selection apparatus for supplying an output signal derived from first, second and third redundant input signals wherein said first redundant input signal is a more precise signal than said second and third redundant signals in that the information conveyed by said redundant signals is more accurately represented by said more precise signal than said information is represented by the less precise second and third redundant input signals, said signal selection apparatus comprising:
-
signal selection logic responsive to first, second and third signal failure signals for supplying first, second and third signal selection signals, said first, second and third signal failure signals being respectively associated with said first, second and third redundant signals, each of said first, second and third signal failure signals having a first predetermined value when said associated redundant signal is supplied by a fully operational signal source, each of said first, second and third signal failure signals having a second predetermined value when said associated redundant signal is supplied by a non operational signal source, said signal selection logic including means for supplying a logic signal wherever the magnitude of said first redundant signal deviates from the magnitude of each of said second and third redundant signals by a first predetermined amount, said logic signal being a first predetermined value when said deviation between said magnitude of said first redundant signal and said magnitudes of said second and third redundant signals exceeds said first predetermined amount and being a second predetermined value when said deviation between said magnitude of said first redundant signal and said magnitudes of said second and third redundant signals is less than said first predetermined amount, said signal selection logic including means for supplying said first signal selection signal when said first failure signal is of said first predetermined value and either of said second and third failure signals is of said second predetermined value or said logic signal is of said second predetermined value, said signal selection logic means including means for supplying said second signal selection signal when said first, second and third failure signals are said first predetermined value and said logic signal is of said first predetermined value, said signal selection logic means further including means for supplying said third signal selection signal when said first failure signal is said second predetermined value; and
,signal consolidation means responsive to said first, second and third redundant signals and responsive to said first, second and third signal selection signals for supplying said output signal, said signal consolidation means including first signal combining means for combining said second and third redundant signals to supply a first weighted signal mathematically equal to the sum of one-half the instantaneous value of said second redundant signal and one-half the instantaneous signal value of said third redundant signal, said signal consolidation means including second signal combining means for combining said first redundant signal and said first weighted signal to supply a second weighted signal mathematically equal to the sum of one-half the instantaneous value of said first redundant signal and one-half the instantaneous value of said first weighted signal, said signal consolidation means including first, second and third signal paths individually and respectively associated with said first, second and third signal selection signals, said first signal path including means for supplying said first redundant signal as said output signal when said associated first signal selection signal is supplied by said signal selection logic, said second signal path including means for supplying said second weighted signal as said output signal when said associated second signal selection signal is supplied by said signal selection logic, said third signal path including means for supplying said first weighted signal as said output signal when said associated third signal selection signal is supplied by said signal selection logic. - View Dependent Claims (11, 12, 13)
-
-
14. A triply redundant signal selection system comprising:
-
first, second and third redundant signal sources for supplying first, second and third redundant signals, and first redundant signal source being a precision signal source for supplying a more precise signal than the signals supplied by said second and third signal sources; failure detection means for defining an operational state and a failure state for each of said first, second and third signal sources, said failure detection means including first comparator means responsive to said first, second and third redundant signals for comparing said first, second and third redundant signals one with another, said first comparison means including means for supplying a first failure signal having a first predetermined value when said first redundant signal is greater than each of said second and third redundant signals by a predetermined amount and having a second predetermined value when said first redundant signal does not exceed said second and third redundant signals by said predetermined amount, said first comparator means including means for supplying a second failure signal having a first predetermined value when said second redundant signal is greater than each of said first and third redundant signals by a predetermined amount and having a second predetermined value when said second redundant signal does not exceed said first and third redundant signals by said predetermined amount, said first comparator means further including means for supplying a third failure signal having a first predetermined value when said third redundant signal is greater than each of said first and second redundant signals by a predetermined amount and having a second predetermined value when said third redundant signal does not exceed said first and second redundant signals by said predetermined amount; signal selection logic means responsive to said first, second and third redundant signals and responsive to said first, second and third failure signals for supplying signal selection signals, said signal selection logic including second comparator means responsive to said first, second and third redundant signals for detecting when said first redundant signal deviates from both said second and third redundant signals by at least a predetermined signal deviation, said second comparator means including means for supplying a suspect state signal having a first predetermined value when said deviation of said first redundant signal from said second and third redundant signals exceeds said predetermined signal deviation and having a second predetermined value when said deviation of said first redundant signal from said second and third redundant signals does not exceed said predetermined signal deviation, said signal selection logic means including means for supplying a first selection signal when said first failure signal is said second predetermined value concurrently with one of said second and third failure signals being said first predetermined value and for supplying a first selection signal when said first failure signal is said second predetermined value concurrently with said suspect state signal being said second predetermined value; and signal consolidation means responsive to said first, second and third redundant signals and said selection signals supplied by said signal selection logic for supplying an output signal derived from said first, second and third redundant signals, said signal consolidation means including first signal control means responsive to said first signal selection signal for supplying said first redundant signal as said output signal whenever said first signal selection signal is supplied by said signal selection logic means, said signal consolidation means including second signal control means responsive to said first signal selection signal for supplying a first mathematically weighted signal including equal signal contribution from at least said second and third redundant signals whenever said first signal selection signal is not supplied. - View Dependent Claims (15, 16)
-
Specification