VEHICLE CONTROLLER EMPLOYING PASSIVE HORIZON SENSOR

• US 3,706,988 A
• Filed: 11/04/1965
• Issued: 12/19/1972
• Est. Priority Date: 11/04/1965
• Status: Expired due to Term

• Current Assignee: Guy P. Bayle, Richard K. Smyth, Robert D. Gustafson
• Original Assignee: Guy P. Bayle, Richard K. Smyth, Robert D. Gustafson
• Inventors: Bayle, Guy P., Smyth, Richard K., Gustafson, Robert D.
• Primary Examiner(s): Tubbesing, T. H.
• Application Number:
  US04/506,295
• Time in Patent Office: 2,602 Days
• Field of Search: 343/6,7,7TA,6R 244/77,77D
• US Class Current: 342/52
• CPC Class Codes: G01S 13/935 for terrain-avoidance

Abstract

A terrain avoidance system for airborne use and employing a forward-looking, nodding, non-radiating sensor (or radiometer) for sensing the direction of the horizon, in cooperation with a downward-looking radar altimeter, whereby the probability of over-the-horizon detection of a utilizing aircraft is minimized.

Claims

1. In a multi-mode control system for enabling a vehicle trajectory to be controlled so as to closely follow a terrain profile without the vehicle being obstructed by such terrain profile, the combination comprising:

Forward-looking vertically-scanning passive sensing means for providing a signal indicative of the vertical direction angle of the horizon; and

Control Mode switching means responsive to said direction angle signal for selectively switching said control system to an optimal one of an altitude control mode and flight path angle control mode for avoiding prematurely flying up in response to a sensed terrain obstacle.

2. In a multi-mode control system having both an altitude control mode and a flight path control mode for enabling a vehicle trajectory to be controlled so as to closely follow a terrain profile without the vehicle being obstructed by such terrain profile, the combination comprising:

Forward-looking vertically-scanning passive sensing means for providing a signal indicative of the vertical direction angle of the horizon; and

Control mode switching means responsive to the state of said direction angle for selectively switching said control system to an optimal one of an altitude control mode and flight path angle control mode for avoiding prematurely flying up in response to a sensed terrain obstacle.

3. In a vehicle-borne multi-mode control system for enabling a vehicle trajectory to be controlled so as to closely follow a terrain profile without the vehicle being obstructed by such terrain profile, said system having altitude signalling means for providing an altitude control signal indicative of the deviation of said vehicle from a selected altitude above the terrain, the combination comprising:

Forward-looking vertically-scanning passive sensing means for providing a signal indicative of the vertical direction angle of the horizon;

Control mode switching means for selectively feeding preselected one of said control and direction angle signals to the input of said control system in response to a preselected state of said sensed direction angle.

4. The device of claim 3 in which said switching means comprises Gating means responsive to a preselected function of said direction angle and a reference signal for gating said direction angle signal in response to an amplitude sense of a preselected sense between said preselected function and said reference signal;

and Signal selecting means responsive to said altitude control signal and said gated direction angle signal for selectively coupling to the input of said control system that one of said control and gated direction angle signals corresponding to a maximum fly-up maneuver.

5. In a vehicle-borne system for enabling a vehicle trajectory to be controlled so as to closely follow a terrain profile without the vehicle being obstructed by such terrain profile, said system having altitude signalling means for providing an altitude control signal indicative of the deviation of said vehicle from a selected altitude above the terrain, the combination comprising:

Forward-looking vertically-scanning passive sensing means for providing a signal indicative of the vertical direction angle of the horizon;

Means responsive to said direction angle signal for providing a signal indicative of the rate of change of said direction angle; and

Switching means for selectively feeding an alternate one of said control and direction angle signals to the input of signal utilization means for control of said vehicle, said control signal being fed in response to a combination of preselectively small direction angle and preselectively low angular rate.

6. The device of claim 5 in which said switching means comprises, in combination:

A first and second summing amplifier, each having a first and second gated input, the gain of said second amplifier being greater than that of said first amplifier, said first gated inputs of said amplifiers being commonly responsive to said direction angle signal, each of said second gates inputs of said amplifiers being coupled to a respective signal reference source for providing an associated component output for an associated one of said amplifiers of like amplitude and sense and corresponding to the absence of a terrain obstacle;

A first and second gatinG circuit, each having a first and second input and providing a first and second gating output signal of mutually opposite states for oppositely gating respective ones of said gated inputs of a respective one of said amplifiers, in accordance with the sense of the difference between two applied input signals to said gating circuit, said first gating circuit being responsive to the sense of the amplitude difference between the horizon angle and a first preselected reference, and said second gating circuit being responsive to the sense of the amplitude difference between the rate of change of said horizon angle and a second preselected reference; and

Signal selecting means comprising a plurality of like-poled diodes, each having a like electrode commonly coupled to form an output terminal and a second electrode coupled to a mutually exclusive one of said summing amplifiers and said altitude signalling means for selecting that one of the input signal representing the greatest fly-up maneuver signal as an output signal to the the input of said utilization means.

7. In a vehicle borne system for enabling a vehicle trajectory to be controlled so as to closely follow a terrain profile without the vehicle being obstructed by such terrain profile, the combination comprising Altitude signalling means for providing an altitude control signal indicative of vehicle deviation from a selected altitude above the terrain;

Forward-looking vertically scanning passive sensing means for providing a signal indicative of the vertical direction angle gamma c of the horizon;

Means responsive to said direction angle signal for providing a signal indicative of the rate of change gamma c of said direction angle;

Gating means responsive to said direction angle and angular rate signals for providing control signals indicative of an alternative one of three logic states, the first state corresponding to a preselectively large direction angle and a preselectively low rate of change of gamma c, the second corresponding to a preselectively high rate of change of gamma c, and the third corresponding to said preselectively small direction angle and said preselectively low rate of change of gamma c; and

Signal selecting means responsive to said control signals for selectively feeding an alternate one of said altitude control and said direction control signals to the input of signal utilization means for control of said vehicle, said direction control signal being selected during said first and second states, the gain of said selected direction signal being increased in said second state.

8. In a system adapted for airborne use for enabling a vehicle trajectory to be controlled so as to closely follow a terrain profile without the vehicle being obstructed by such terrain profile, said system having altitude signalling means for providing an altitude control signal indicative of the deviation of said vehicle from a selected altitude above the terrain, the combination comprising forward-looking vertically-scanning passive sensing means for providing a signal indicative of the vertical direction angle of the horizon;

means responsive to said direction angle signal for providing a signal indiative of the rate of change of said direction angle;

means responsive to said first and second mentioned means for feeding a selected one of said altitude control and direction angle signals to an input of signal utilization means for control of said vehicle, said direction angle signal being fed in response to each of a preselectively large direction angle and preselectively high directional angular rate of change.

9. The device of claim 8 in which said last mentioned means comprises gain adjusting means responsive to said direction angle signal and to said rate of change for preselectively increasing the gain of said direction angle signal in response a direction angle rate of change having a preselected sense and aT least a preselected minimum magnitude;

and logic means for selectively feeding the greater of said altitude control, direction angle, and gain-increased direction angle signals as as input to said signal utilization means.