Optimized state feedback regulation of 3DOF helicopter system via extremum seeking

In this paper, an optimized state feedback regulation of a 3 degree of freedom (DOF) helicopter is designed via extremum seeking (ES) technique. Multi-parameter ES is applied to optimize the tracking performance via tuning State Vector Feedback with Integration of the Control Error (SVFBICE). Discrete multivariable version of ES is developed to minimize a cost function that measures the performance of the controller. The cost function is a function of the error between the actual and desired axis positions. The controller parameters are updated online as the optimization takes place. This method significantly decreases the time in obtaining optimal controller parameters. Simulations were conducted for the online optimization under both fixed and varying operating conditions. The results demonstrate the usefulness of using ES for preserving the maximum attainable performance

RICIS Symposium 1988

Integrated Environments for Large, Complex Systems is the theme for the RICIS symposium of 1988. Distinguished professionals from industry, government, and academia have been invited to participate and present their views and experiences regarding research, education, and future directions related to this topic. Within RICIS, more than half of the research being conducted is in the area of Computer Systems and Software Engineering. The focus of this research is on the software development life-cycle for large, complex, distributed systems. Within the education and training component of RICIS, the primary emphasis has been to provide education and training for software professionals

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 406)

This bibliography lists 346 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during Oct. 1995. Subject coverage includes: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance

Catalog 1996-97

https://openspace.dmacc.edu/catalogs/1020/thumbnail.jp

DIRECT AND INDIRECT TORQUE CONTROL OF UNBALANCED PERMANENT MAGNET SYNCHRONOUS MACHINES

Electrical machines may exhibit various types of imbalances and undesirable harmonic distortions. These may increase the torque and flux ripples, acoustic noise, unbalanced three-phase currents, while also reducing efficiency. These types of imbalances and undesirable harmonic distortions cannot be controlled by using the conventional indirect torque control (ITC) and direct torque control (DTC) strategies. For some high-performance motion control, such as precision machine tools, robotics, and servo drives, low torque ripples are, however, obligatory. Nowadays, more studies have been conducted on the ITC strategy to control undesired current harmonics, such as double synchronic reference frames (DSRF), resonant controller, second order generalized integration, and reference current generation. Such strategies, however, can rarely be applied to DTC strategy. In this research, the influence of asymmetric winding impedances, unbalanced back-EMF, and inverter nonlinearity in three-phase surface-mounted PMSMs has been systematically investigated by employing space vector modulations (SVM) based ITC and DTC strategies. This thesis firstly presents a modified ITC strategy by extracting the positive and negative sequence components in the stationary abc frame, and then a coordination transformation is used to control the machine in DSRF. This strategy provides faster dynamic response when compared with the conventional DSRF strategy, since the filters and the decoupling network are not required. Due to the lack of research regarding the DTC strategy under unbalanced conditions, this research investigates and proposes modified cascaded and parallel DTC-SVM strategies. The conventional cascaded DTC strategy is investigated under balanced and unbalanced conditions. Then, a modified control strategy is introduced by adding two compensators (the conventional PI-controller with a resonant controller, and the use of the negative- and positive-sequence voltage vectors) to suppress the 2nd harmonic components in the torque and stator flux linkage. Furthermore, for parallel DTC-SVM, the compensation of the 2nd and 6th harmonic components is investigated by means of either a resonant controller or an adaptive filter. In addition to the simplicity of the proposed strategies, these may also be able to significantly reduce the torque and flux ripples, while maintaining the merit of the fast dynamic response of the conventional DTC strategy even under variable fundamental frequency. Moreover, it has been proven that the compensation from using a resonant controller or an adaptive filter is parameter independent. Thus, regardless of unbalanced conditions, an effective torque ripple minimisation can still be achieved by properly selecting the dominant harmonic compensation