Abstract: A self-contained pen computer is provided that is capable of acquiring data representative of written strokes of the stylus of the pen and then recognizing the symbols associated with these pen strokes, or compacting these strokes. These recognized symbols or compacted strokes are stored in a memory contained in the pen and are transmitted via a transmitter contained in the pen to a host computer.

Abstract: A method and system for range detection using a passive infrared sensing device (10) is disclosed. The method includes determining a region (35,38) on a moving object, such as an automobile (13, 36, 37), the region (35, 38) having a size characteristic of the object and emitting energy (14) characteristic of the object. The next step is to characterize the region by a plurality of feature points (31, 32, 33, 34) and sense the energy emitting from the feature points. The next step is to calculate the distance between the sensing device (10) and the moving object as a function of the feature points. The method has application in adaptive cruise control for automobiles (13, 36, 37). The method includes the use of perspective projection formulae to determine the distance between the sensing device (10) and the moving object 13, 36, 37). To smooth measurements to each other, one embodiment of the method includes the use of an Euler predictor to integrate measurements across measurement firmness.

Abstract: A method for passive relative ranging between a position of a moving observer and a stationary remote object includes measuring a plurality of angles at the observer's position to the object from a reference direction at selected or arbitrary time intervals. From the measured angles, calculating the current relative location of the observer with respect to the object, using a non-recursive least square technique employing a Moore-Penrose pseudo-matrix-inverse. The technique is carried out in a general or special purpose digital computer by a program using a predetermined number of variables in which products derived from the measured angles are accumulated, without growth in the number or complexity of calculations with an increasing number of measured angles.