Engineering topics
Publications and source records attributed to Hung, J. C..
The analysis of the pulse rebalance loop where the pulses are of constant amplitude type is presented. Properties of such systems are discussed. Sensor errors caused by the distortion of the pulse shape, the dc bias, and the sampling process are analyzed.
A new concept of high reliability strapdown attitude sensing systems for space vehicles is presented. Each system utilizes a set of redundant two-degree-of-freedom gyros. An optimum system configuration is obtained for maximum system reliability and the best measurement accuracy. Improved accuracy of the final data is obtained by using the least-square data reduction technique. Each system possesses a sensor performance management feature which is capable of failure detection, faulty gyro identification, system reconfiguration, and possibly, sensor recalibration. Improvement in reliability as compared to other types of strapdown systems is demonstrated. Details of the development are described in terms of a system containing four gyros.
The attitude algorithms applied to strapdown inertial platforms are discussed. A review of six attitude transformation algorithms and the realizations of these algorithms by digital differential analyzers are presented. The number of digital differential analyzers for each algorithm is either smaller than or equal to that obtained by others.
Two new methods for navigation on the land are reported. Both methods make use of landmarks which are in sight but whose positions are not known. Only angle measurements are needed. Although the methods were intended for guiding a Lunar Roving Vehicle as it travels on the lunar surface, they may also find applications on other planets as well as on earth. Besides the mathematical details, two examples are also included to demonstrate the correctness of the method.
Digital differential analyzer (DDA) realization of the direction cosine, Euler angle, and quaternion algorithms. It is shown that, for any one of the three attitude algorithms, 27 DDAs are needed. This number is considerably smaller than those obtained by others for the cases of Euler angle and quaternion algorithms.
Celestial and satellite navigation sensitivity for Lunar roving vehicle /LRV/ position fix
Solar aspect sensors as navigation components for rolling vehicle heading angle determination
Manned lunar roving vehicle /MLRV/ navigation scheme based on dead reckoning concept, discussing instruments effectiveness for vehicle velocity and orientation measurements
Minimum sensitivity deadbeat sampled data control system design by frequency domain technique, using two controllers
Hydraulic controller possessing property of automatic tracking notch filter for open loop thrust engine control
Study of statistical techniques for obtaining estimates of true data parameters uses discrete measured quantities containing random error. These techniques develop estimation procedures as an iterative algorithm for digital computation in real time.
Low sensitivity sampled-data control systems design
Sample mean and Kalman estimator relationship, noting Kalman filter generality
Statistical techniques for missile injection error analysis, discussing direct and adjoint methods
Nonlinear dynamics discrete estimation by computational algorithm involving nonlinear algebraic equations
Time-weighted minimal energy control of nth order plant
Formulation of direct and adjoint methods of trajectory injection error in vector matrix notation and comparison
Nonlinear control of pulse amplitude modulated sampled-data systems