Hughes Aircraft Company

Raytheon Company

Hughes Electronics Corporation

Ronald E Huss

Robert E Vitali

Robert M Denlinger

Mark A Pumar

Ellis S Feldman

In missile guidance systems, knowledge of the target's flight policy and doctrine, along with an analysis of local topographic features, are used in a minimum commitment guidance policy. By assuming certain objectives of the target, paths may be defined by evaluating the degree of detection avoidance provided by the terrain adjacent to the various paths. To maximize the probability of intercept, a missile may be guided in a direction covering the most likely of these paths for periods while the target is hidden. The paths are then reevaluated each time the target is detected. For highly maneuverable targets that are capable of executing violent changes in direction and speed, the topography-aided guidance system maximizes the probability that the target can escape the missile intercept envelope. The present invention relates to a topographay-aided missile guidance system that minimzes the probability that an airborne target can escape the missile's intercept envelope, where the minimization is over substantially all of the potential actions that the target may take.

Topography-aided guidance system and process

A method that enables an aircraft to determine an optimal terrain following, terrain avoidance, or threat avoidance trajectory over terrain, thereby reducing its exposure and increasing its survivability. A grid of discrete terrain points corresponding to the terrain above which the aircraft is to fly is formed. Each point has a cost that is function of predetermined criteria. A cost is assigned to each of the points that is representative of the cost to get to the point based upon the predetermined criteria. A terminal point is selected that is a point that must be flown through at the end of the trajectory over the terrain, or in order to clear an obstacle in the flight path of the aircraft. A series of paths is computed through the terrain points to a selected terminal point, taking into account the aircraft's maneuvering capability and current attitude. A total cost at the terminal point is computed for each path, and the total cost for a particular path is the sum of costs at the terminal point plus the respective costs of all terrain points along the path. The path that has the least total cost to arrive at the selected terminal point is selected. The aircraft is then guided along a trajectory defined by the selected path. The present method not only generates trajectories lower than those generated by current procedures, but also identifies regions where natural terrain masking provides cover without requiring extremely low flight, thus reducing the stress on both aircraft and pilot.

Method for determining terrain following and terrain avoidance

A method for presenting intervisibility data relative to an observation point. A data base of terrain altitudes is stored in computer memory. The data base comprises terrain altitudes at a grid of points in a selected terrestrial area encompassing the observation point. Visible heights from the observation point at the grid points are derived from the data base with a computer by performing a number of steps grid point by grid point in succession in an order moving away from the observation point. The first step is to determine a projected height at the grid point from the visible heights between the observation point and the grid point. The second step is to compare the projected height with the terrain altitude at the grid point. The third step is select as the visible height at the grid point the larger of the compared terrain altitude and the projected height. A number representative of the visible height at each grid point as so derived with a computer is stored in computer memory. The computer memory is coupled to a visual display device to present the stored representations of the visible height in spatial relationship coordinated with the spatial relationship of the grid points of the terrestrial area. The visible height data is derived by use of the similar triangles theorem, and interpolation of previously calculated visible heights.

Method for displaying intervisibility data

A radio frequency emitter transmits pulses in a regular swept beam pattern. As a result of this regular pattern, the angles of transmission of the pulses can be inferred. Intervisibility data of terrain points in a region around an observation point are stored in computer memory. At the observation point, measurements are made of the times of arrival of a plurality of terrain point reflections of a single pulse transmitted by the emitter. These measurements are repeated for a plurality of pulses transmitted by the emitter. In a computer, a comparison is made of the terrain points of reflection calculated from the measured times of arrival for assumed emitter locations with the stored intervisibility data of terrain points.

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Los Angeles, CA, United States of America

Ronald E Huss