Harris Corporation

John J Maney

Robert Fred Varley

Michael R James

A method of automatically isolating item faults is disclosed. Subtest results T&lsqb;i&rsqb; are obtained for a plurality of items, where T&lsqb;&rsqb; comprises a vector of m subtest results and T&lsqb;i&rsqb;&equals;a value if subtest i fails and subtest i does not fail, T&lsqb;i&rsqb;&equals;a negative value or 0. The subtest results T&lsqb;i&rsqb; are multiplied or ANDed with respective matrix values Y&lsqb;i,j&rsqb;, where Y&lsqb;&rsqb; comprises a predetermined m&times;n matrix where Y&lsqb;i,j&rsqb;>0 if hardware module j causes subtest i to fail and Y&lsqb;i,j&rsqb;&lE;0 if item j does not cause subtest i to fail. The results are summed in order to obtain a number S&lsqb;j&rsqb; for each item that is reflective of the number of subtest failures that are explained by a failure of item j, wherein any item j is suspect if S&lsqb;j&rsqb;>0. The item that has the most likely failure is determined by obtaining the largest value of S&lsqb;j&rsqb; when S&lsqb;j&rsqb; has multiple non-zero entries, such that the largest value of S&lsqb;j&rsqb; is indicative of the most likely single item failure where any other items with non-zero S&lsqb;j&rsqb; represent alternate possible item failures.

Method for automatically isolating hardware module faults

A hybrid system for stabilizing the attitude of an instrument relative to a dynamic platform includes a plurality of (roll, pitch and yaw) inertial rate sensors, whose outputs are sampled at a rate sufficient to provide real time tracking of changes in orientation of the platform, and a global positioning system (GPS) receiver, whose precision platform attitude output is updated periodically, but at a rate less than the rate of change of attitude of the platform. The inertial rate sensors provide effectively continuous motion (e.g., angular rate) data signals representative of three-dimensional changes in attitude (position derivative signals) of the platform. The inertial rate output are integrated to provide output signals representative of the dynamic orientation of the platform. Sequential outputs of the integration-processing circuitry are also coupled to a sample buffer, which is controllably read-out in accordance with the periodic updates from the GPS receiver. The integrated inertial sensor (attitude) data is compared with the GPS update data to generate error signals which are used to adjust the inertial sensor data. By employing a sample buffer in an inertial sensor output integration feedback loop with the GPS receiver, the hybrid system of the present invention avoids what would otherwise be a staleness problem with the data provided by the GPS receiver.

Hybrid GPS/inertially aided platform stabilization system

A method of and an apparatus for analyzing multi-bit digital words to identify their source or content. The digital words are converted to multi-bit fields, with each field being a portion of the digital word or corresponding to one or more descriptive parameters of the source. Each multi-bit field is analyzed to generate an additional multi-bit field. The additional multi-bit fields are grouped into pairs, and each pair is analyzed to generate a further multi-bit field. The further multi-bit fields are grouped into pairs. If more than one pair exists, the analyzing and grouping into pairs continues until a single pair remains, and that pair is analyzed to identify the source or content. Preferably each of the additional and further fields has the same number of bits, and each of the means for analyzing the additional and further multi-bit fields has twice that number of input bits. If the means for analyzing multi-bit fields has enough input bits, the additional and further fields could be grouped into groups larger than pairs. The analysis of the original fields can be done by comparison of each field with known bit patterns associated with known sources to determine possible sources, or by the application of the fields as the address bits to a programmable memory to select a memory location containing a source number or ID code indicative of possible sources. The subsequent analysis of pairs of fields can be the application of the pairs of fields as the address bits to a programmable memory to select a memory location containing a source number or ID code indicative of common possible sources. Each field can represent more than one parameter, and the analysis of the original fields can look for sources whose parameters closely but not exactly match those in the analyzed fields. The degree and measure of closeness required is selectable during programming of the pattern identifier. The degree of closeness need not be fixed, and the analysis of the original fields can look for the one known source whose parameters most closely match those in the analyzed fields. The method can be carried out by a digital data processor.

Pattern identification by analysis of digital words

An improved torque control for a brushless DC motor is disclosed. A torque command A of a time varying nature is applied to an excitation winding which is magnetically coupled through a resolver to produce output signals respectively on sensing windings of Acosine .theta. and of Asine .theta. wherein .theta. is the angular position of an armature and resolver of the motor. Armature windings respectively coupled to the sensing windings are driven by signals proportional to or equal to the signals sensed by the sensing windings to produce a torque equal to A.

Digital pulse width modulation control of brushless DC motors

A mechanism for correcting for time-varying errors that affect the pointing accuracy of a shipboard mounted antenna employs a Kalman filter for realizing an optimal correction estimator through which inputs to the antenna aiming control hardware are adjusted. A series of coordinate system transformations, corrected by the Kalman filter error estimator, are carried out to provide a command input to an antenna pointing servo system. The servo control system produces a servo error signal representative of a deviation in the actual direction of the antenna pointing mechanism from the command input to the servo loop as defined by the corrected aiming signal. The actual direction in which the servo control system points the antenna is compared with a reference (the actual direction to the satellite). As a result of this comparison, a pointing deviation signal representative of any offset from the intended pointing direction is generated. Because this pointing deviation signal depends upon the output of the servo control mechanism, it inherently contains any error in that output. Such error is removed by subtracting the servo error signal from the pointing deviation signal and applying the resultant difference signal to the Kalman filter error estimator.

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Palm Bay, FL, United States of America

John J Maney