Integrated collision avoidance system for air vehicle

• US 8,509,965 B2
• Filed: 12/04/2007
• Issued: 08/13/2013
• Est. Priority Date: 12/12/2006
• Status: Active Grant

• Current Assignee: American GNC Corporation
• Original Assignee: American GNC Corporation
• Inventors: Lin, Ching-Fang
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): TISSOT, ADAM D
• Application Number:
  US11/999,310
• Publication Number:
  US 20080243383A1
• Time in Patent Office: 2,079 Days
• Field of Search: 701200-215, 701/2, 701/3, 701/23, 701/535, 340/945, 340/961
• US Class Current: 701/3
• CPC Class Codes: G01C 21/1652 with ranging devices, e.g. LIDAR or RADAR
• CPC Class Codes: G01C 21/1656 with passive imaging devices, e.g. cameras
• CPC Class Codes: G01S 13/933 of aircraft or spacecraft
• CPC Class Codes: G01S 13/935 for terrain-avoidance
• CPC Class Codes: G01S 19/15 Aircraft landing systems
• CPC Class Codes: G08G 5/0078 for monitoring traffic from the aircraft radar or analogous systems specially adapted for traffic control G01S13/91
• CPC Class Codes: G08G 5/0086 for monitoring terrain radar or analogous systems specially adapted for terrain avoidance G01S13/935
• CPC Class Codes: G08G 5/045 Navigation or guidance aids, e.g. determination of anti-collision manoeuvers radar or analogous systems specially adapted for anti-collision between aircraft G01S13/933

Abstract

Collision with ground/water/terrain and midair obstacles is one of the common causes of severe aircraft accidents. The various data from the coremicro AHRS/INS/GPS Integration Unit, terrain data base, and object detection sensors are processed to produce collision warning audio/visual messages and collision detection and avoidance of terrain and obstacles through generation of guidance commands in a closed-loop system. The vision sensors provide more information for the Integrated System, such as, terrain recognition and ranging of terrain and obstacles, which plays an important role to the improvement of the Integrated Collision Avoidance System.

Claims

1. An integrated collision system, comprising:

an integrated positioning/ground proximity warning system processor;

a flight control and management system which provides vehicle performance and configuration data;

an imaging sensor which provides recognized local terrain information based on the use of a trained classifier of a user'"'"'s choice and ranged terrain information when using a stereo camera as said imaging sensor;

a global positioning system (GPS) receiver which provides signals necessary for deriving position, velocity, and time information and for selectively doing pseudorange and delta range measurements;

an inertial navigation system (INS) which solves navigation solutions with angular rate and specific force information from an inertial measurement unit (IMU) for outputting an inertial navigation solution with vehicle position, altitude, and velocity;

a baro altimeter which measures air pressure and computes baro altitude measurements;

a radio altimeter which measures a time delay between transmission and reception of a radio signal from a terrain surface and computes radio altitude measurements;

a worldwide digital terrain database which includes terrain height data at the current vehicle position as well as the surrounding area;

a radar for detecting and tracking midair obstacles;

means for filtering and estimation in which information from said GPS receiver, said INS, geographical coordinates, and altitude measurement residuals to obtain optimal estimates of inertial navigation solution errors, errors of said global positioning system receiver, and errors of inertial sensors in a centralized filtering fashion, wherein said filtering means comprises;

a first local filter modeling said inertial navigation solution errors and inertial sensor errors, and filtering said geographic coordinates of the best matching reference profile and said altitude measurement residuals so as to obtain said local optimal estimates of inertial navigation solution errors and inertial sensor errors;

a second local filter inputting said measurements from said global positioning system receiver and inertial navigation solution to obtain local optimal estimates of inertial navigation solution errors, global positioning system receiver errors, and inertial sensor errors; and

a master filter receiving local optimal estimates and covariance matrices of;

(i) inertial navigation solution errors from said first and second local filters, (ii) global positioning system receiver errors from said second local filter, and (iii) inertial sensor errors from said first and second local filters, and by filtering these data provide global optimal estimates of inertial navigation solution errors, global positioning system receiver errors, and inertial sensor errors;

wherein said master filter feeds back said global optimal estimates and covariance matrices of inertial navigation solution errors, global positioning system receiver errors, and inertial sensor errors to said first and second local filters for resetting and for performing information sharing among all three filters;

a synthetic vision system which visually displays the current air vehicle position, projected flight path, warning decision message, surrounding terrain data, and suggested optimal evasion flight path; and

a voice device which indicates a collision avoidance warning.

2. The system, as recited in claim 1, wherein said integrated positioning/ground proximity warning system processor comprises:

a navigation solution module for generating an optimal navigation solution;

a ground proximity warning solution module for generating a midair object proximity warning solution and ground/terrain proximity warning solution; and

an input/output module for managing said navigation solution module, said ground proximity warning solution module, said flight control and management system, said imaging sensor, said GPS receiver, said INS, said baro altimeter, said radio altimeter, said worldwide digital terrain database, said synthetic vision system, and said voice device.

3. The system, as recited in claim 2, wherein said navigation solution module comprises:

a correlation/matching module; and

a filter/estimator module consisting of two local filters and a master filter.

4. The system, as recited in claim 1, wherein said radar is a moving target indicator (MTI) radar.

5. An integrated collision avoidance method for a host vehicle, comprising the steps of:

(a) generating an optimal estimate of said host vehicle'"'"'s current position, altitude, and velocity by the steps of;

(a.1) using an imaging sensor which provides recognized local terrain information based on the use of a trained classifier of a user'"'"'s choice and ranged terrain information when using a stereo camera;

(a.2) using a global positioning system (GPS) receiver which provides signals necessary for deriving position, velocity, and time information and for selectively doing pseudorange and delta range measurements;

(a.3) using an inertial navigation system (INS) which solves navigation solutions with angular rate and specific force information from an inertial measurement unit (IMU) for outputting an inertial navigation solution with vehicle position, altitude, and velocity;

(a.4) using a baro altimeter which measures air pressure and computes baro altitude measurements;

(a.5) using a radio altimeter which measures a time delay between transmission and reception of a radio signal from a terrain surface and computes radio altitude measurements; and

(a.6) using said worldwide digital terrain database which includes terrain height data at the current vehicle position as well as the surrounding area;

wherein said optimal estimate of said host vehicle'"'"'s current position, altitude, and velocity requires data fusion which comprises the steps of;

correlation and matching in which said signals from said imaging sensor, said INS, said baro altimeter, said radio altimeter, and said worldwide digital terrain database are collected to construct a measured profile of said terrain in an assigned time window which is then compared with a set of pre-stored reference terrain profiles for outputting (i) geographical coordinates of the best matching reference profile, and (ii) differences that result from adding said radio altimeter measurements, and said terrain height at said current vehicle position, and said inertial altitude solution for forming altitude measurement residuals; and

filtering and estimation in which the information from said GPS receiver, said INS, said geographical coordinates, and said altitude measurement residuals are filtered to obtain optimal estimates of inertial navigation solution errors, errors of said global positioning system receiver, and errors of inertial sensors in a centralized filtering fashion which comprises the steps of;

using a first local filter to model said inertial navigation solution errors and inertial sensor errors, and to filter said geographic coordinates of the best matching reference profile and said altitude measurement residuals so as to obtain said local optimal estimates of inertial navigation solution errors and inertial sensor errors;

using a second local filter to input said measurements from said global positioning system receiver and inertial navigation solution to obtain local optimal estimates of inertial navigation solution errors, global positioning system receiver errors, and inertial sensor errors;

using a master filter to receive local optimal estimates and covariance matrices of;

(i) inertial navigation solution errors from said first and second local filters, (ii) global positioning system receiver errors from said second local filter, and (iii) inertial sensor errors from said first and second local filters, and by filtering these data provide global optimal estimates of inertial navigation solution errors, global positioning system receiver errors, and inertial sensor errors; and

feeding back said global optimal estimates and covariance matrices of inertial navigation solution errors, global positioning system receiver errors, and inertial sensor errors from said master filter to said first and second local filters for resetting and for performing information sharing among all three filters; and

(b) predicting a flight path by said host vehicle future position, altitude and velocity;

(c) predicting a terrain collision based on said flight path prediction and terrain environment;

(d) providing visual and voice alerts if said terrain collision is possible; and

(e) computing a flight path aiding with an optimal escaping method by fusing information from said warning decision, current vehicle position, altitude, and velocity, terrain environment, and vehicle performance and configuration data.

6. The method as recited in claim 5 wherein, in the step (b), wherein said prediction of said host vehicle future position, altitude and velocity is accomplished by fusing position, altitude, and velocity from said optimal navigation solution, vehicle performance configuration data from an on-board flight control and management system, and terrain information from said imaging sensor.

7. The method as recited in claim 5, before the step (d), further comprising a step of determining a ground/terrain proximity warning solution which comprises the steps of:

determining said terrain environment based on information from said worldwide digital terrain database as well as local recognized terrain based on said imaging sensor and local ranged terrain when using said stereo camera as said imaging sensor; and

comparing information regarding said terrain environment and a projected flight path for predicting a terrain collision and issuing a warning decision.

8. The method as recited in claim 5, before the step (d), further comprising a step of determining a midair object proximity warning solution by the steps of:

detecting and tracking midair obstacles based on midair obstacle detection radar and imaging;

recognizing midair obstacles based on said imaging sensor and ranging local obstacles when using said stereo camera as said imaging sensor; and

comparing information regarding said midair obstacles and said projected flight path for predicting a midair collision and issuing said warning decision.