Profile warning generator with anticipation of warning condition

• US 4,071,894 A
• Filed: 06/28/1976
• Issued: 01/31/1978
• Est. Priority Date: 06/28/1976
• Status: Expired due to Term

• Current Assignee: Rockwell International Corporation
• Original Assignee: Rockwell International Corporation
• Inventors: Schuldt, Theodore J.
• Primary Examiner(s): Morrison, Malcolm A.
• Assistant Examiner(s): Krass, Errol A.
• Application Number:
  US05/700,634
• Time in Patent Office: 582 Days
• Field of Search: 235/151.3, 235/150.22, 340/213 R, 340/248 R, 340/248 C, 340/27 R, 340/27 AT, 307/293, 328/1, 343/7 TA, 343/112 C, 343/112 A, 244/180, 244/181, 244/185-187, 73/178 R, 73/178 T
• US Class Current: 701/18
• CPC Class Codes: G01C 5/005 altimeters for aircraft G01C5/02, G01C5/06 take precedence
• CPC Class Codes: G08G 5/0052 for cruising combined instruments indicating more than one navigational value G01C23/00

Abstract

A system for developing a warning condition output signal when a monitored input variable exceeds a warn profile defined value defined as a predetermined function of an input reference variable, in which the warning condition output signal is delayed by a time τ from the time that a warning condition is sensed. The profile offset thus induced is compensated for by generating an anticipated future value of the reference variable after a time τ from the instant value and rate of change thereof, with the anticipated future value being utilized to generate the warn profile. Lag introduced by filtering which might be employed in generating the anticipated value, as well as any lag time existing between a reference variable failure and a failure condition signal which may be used to inhibit development of a warning condition signal, are then permissible, and are compensated for without profile offset by choosing a delay time τ at least as great as the cumulation of these delays, and conditioning generation of a delayed warning condition signal on a warning signal condition being continuously maintained for a time at least as great as the imposed delay time τ.

Claims

1. A system for generating an output warning condition signal when a monitored input variable exceeds a reference profile value defined by a predetermined function of an input reference variable, comprising, signal generation means receiving said reference variable as input thereto and developing from the instant value and rate of change thereof a calculated future value of said reference variable after a time interval τ

, said calculated future value being applied to a profile generating means to output said reference profile, comparator means receiving said monitored input variable and said reference profile value as respective inputs thereto and developing an output signal in response to said monitored input variable exceeding said reference profile value, signal delay means receiving the output from said comparator means and imparting thereto a delay equated to said time interval τ

, and the output of said delay means comprising said output warning condition signal.

2. The system of claim 1 wherein said signal generation means comprises rate deriving means receiving said input reference variable and developing an output proportional to the rate of change with time thereof, signal multiplying means receiving the output of said rate deriving means and multiplying same by said time τ

, and means for summing the outputs of said signal multiplying means with said reference input signal, the output of said means or summing comprising said calculated future value of said reference variable.

3. The system of claim 2, with said signal generation means further comprising low-pass filtering means imparting a predetermined lag time to the calculated future value of said reference variable outputted thereby, and said time interval τ

being at least as great as said lag time.

4. The system of claim 3, with logic gating means receiving the output of said signal comparator means and a reference variable validity indicative signal as respective inputs thereto and selectively gating the output of said comparator means to said signal delay means under conditions of reference variable validity, with a further time delay between a failure condition of said reference variable and indication of said failure condition by loss of said validity indication signal, and said time interval τ

being at least as great as the cumulation of said filter induced lag time and said further time delays.

5. The system of claim 4 with said delay means including means precluding an output therefrom for signals inputted thereto having time durations less than said time interval τ

.

6. The system of claim 5, wherein said delay means comprises a digital counter, a clock source applied to the clock input of said counter, means for resetting said counter to zero upon termination of a warning condition definitive signal logic level inputted thereto, said warning condition output comprising a predetermined Q output from said counter, and means responsive to said predetermined Q output to inhibit application of clock pulses to said counter.