Engineering topics
Publications and source records attributed to Ih, Che-Hang C..
Torque actuator and associated control system minimizes effective friction of rotary bearing. Motor exerts compensating torque in response to feedback from external optical sensor. Compensation torque nearly cancels frictional torque of shaft bearings. Also useful in reducing bearing friction in gyro-scopes, galvanometers, torquemeters, accelerometers, earth-motion detectors, and balances.
Report describes theoretical and experimental study of robustness of adaptive model-reference control scheme designed to suppress vibrations in large, flexible structure. Model can be mathematical model or collection of models approximating dynamics of structure, vibration sensors, and vibration-suppressing actuators.
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Nonlinear equations solved with linear approximations applicable during small increments of time. Report presents theoretical study of selected aspects of dynamics and control of robotic manipulator that includes multiple flexible links. Addresses problem of control primarily from perspective of inverse-dynamics problem.
Report discusses mathematical modeling of vibrations and active control to suppress vibrations of large, segmented telescope reflector. Vibrating structure treated as collection of substructures, each initially treated separately. Vibrations suppressed considerably, in comparison with open-loop vibration-attenuation mechanism.
Report describes experiments in use of six-input/six-output multivariable adaptive control system to suppress vibrations in complicated flexible structure. Represents significant upgrade relative to two-input/two-output system, yielding significant improvement in spatial controllability and effective damping of largest set of modes. Structure exhibits low modal frequencies and complicated dynamics like those of large structures in outer space. Conclusions drawn from research relevant to such applications as active suppression of wind and earthquake vibrations in tall buildings and other large terrestrial structures.
Antennalike flexible structure built for research in advanced technology including suppression of vibrations and control of initial deflections. Structure instrumented with sensors and actuators connected to digital electronic control system, programmed with control algorithms to be tested. Particular attention in this research focused on direct model-reference adaptive-control algorithm based on command generator tracker theory. Built to exhibit multiple vibrational modes, low modal frequencies, and low structural damping. Made three-dimensional so complicated interactions among components of structure and control system investigated.