The nonlinear inverse dynamics (NID) methodology and its specific application to flight control using a promising control device, the spoiler, are studied, The proper control modeling of spoiler aerodynamics leads to ...
详细信息
The nonlinear inverse dynamics (NID) methodology and its specific application to flight control using a promising control device, the spoiler, are studied, The proper control modeling of spoiler aerodynamics leads to a generic nonlinear model for the most typical aft-mounted spoilers that is then included in a complete nonlinear aircraft model. A novel systematic design procedure for the synthesis of robust NID-based flight control systems is presented, Use of the methodology for a modern combat aircraft, the Hawk trainer, leads to the development of a multimode longitudinal flight control system, with the particular aim of using spoilers as an active control device. Promising applications of spoilers for active control of aircraft are studied, and the related control configurations designed, Simulation results for aircraft maneuvering are presented, demonstrating the effectiveness of spoilers for aircraft maneuver enhancement and, in particular, in ameliorating the effects of wind shear and microbursts.
Sufficient conditions for the asymptotic stability and exponential convergence of tracking control for nonlinear systems have proliferated in recent research, Various theories for stability have been related to, and r...
详细信息
Sufficient conditions for the asymptotic stability and exponential convergence of tracking control for nonlinear systems have proliferated in recent research, Various theories for stability have been related to, and rely upon, the functional form of the governing nonlinear equations, the linearizability of the governing equations by canonical (Lie) transformations, the linear appearance of adaptive parameters, and the richness of the input excitation. Previously, sufficient conditions have been derived for a class of Hamiltonian adaptive tracking control problems using radial basis function approximants. We demonstrate that a crucial element determining the performance of this class of tracking control methodologies is the location of the centers of approximation in the radial basis approximant/network. A learning vector quantization algorithm is employed to simultaneously adapt both the centers of approximation and the feedback gains. The simultaneous adaptation of both approximant centers in configuration space and feedback gains can demonstrate remarkable improvements in convergence rate, as compared to adaptation of feedback gains alone.
A three-channel active control system is applied to an operational turbofan engine to reduce tonal noise produced by both the fan and the high-pressure compressor. The control approach is the feedforward filtered-x le...
详细信息
A three-channel active control system is applied to an operational turbofan engine to reduce tonal noise produced by both the fan and the high-pressure compressor. The control approach is the feedforward filtered-x least-mean-square algorithm implemented on a digital signal processing board. Reference transducers mounted on the engine case provide blade passing and harmonics frequency information to the controller. Error information is provided by large area microphones placed in the acoustic far field. To minimize the error signal, the controller actuates loudspeakers mounted on the inlet to produce destructive interference. The sound pressure level of the fundamental tone of the fan was reduced using the three-channel controller by up to 16 dB over a +/- 30-deg angle about the engine axis. A single-channel controller could produce reduction over a +/- 15-deg angle. The experimental results show the control to be robust. Outside of the areas controlled, the levels of the tone actually increased due to the generation of radial modes by the control sources. Simultaneous control of two tones is achieved with parallel controllers. The fundamental and the first harmonic tones of the fan were controlled simultaneously with reductions of 12 and 5 dBA, respectively, measured on the engine axis. Simultaneous control was also demonstrated for the fan fundamental and the high-pressure compressor fundamental tones.
A controller to rotate a rigid body between two successive orientations is designed. Particular features are the bet that it is based on the quaternion approach, known to provide singularity-free attitude description,...
详细信息
A controller to rotate a rigid body between two successive orientations is designed. Particular features are the bet that it is based on the quaternion approach, known to provide singularity-free attitude description, and it is adaptive in the sense that it does not need specific knowledge of the inertia matrix. Global stability of the overall controller is proved analytically and tested in computer simulations.
A six-input/six-output multivariable adaptivecontroller is used to control a large three-dimensional flexible structure experiment. For this purpose, the Jet Propulsion Laboratory Large Spacecraft control Laboratory ...
详细信息
A six-input/six-output multivariable adaptivecontroller is used to control a large three-dimensional flexible structure experiment. For this purpose, the Jet Propulsion Laboratory Large Spacecraft control Laboratory antenna-like experiment structure is used, with instrumentation distributed on both the hub and the ribs. This represents a significant increase in complexity relative to earlier adaptivecontrol experiments performed on the same structure using a two-input/two-output setup with instrumentation on the hub alone [Ih, C.-H. C., Bayard, D. S., Wang, S. J., and Eldred, D. B., ''adaptivecontrol Experiment with a Large Flexible Structure,'' Proceedings of the AIAA Guidance, Navigation, and control Conference (Minneapolis, MN), AIAA, Washington, DC, Aug. 1988 (AIAA Paper 88-4153)]. The increase in instrumentation significantly increases spatial controllability and excitation and control of a much larger set of modes. This paper documents multivariable adaptivecontrol experiments on this structural configuration and discusses many of the associated design and implementation issues required for successful operation.
Recent progress in the field of active noise control is reviewed. The advent of the digital computer and subsequent speed and capacity improvements have made active noise control more practical and have encouraged rap...
详细信息
Recent progress in the field of active noise control is reviewed. The advent of the digital computer and subsequent speed and capacity improvements have made active noise control more practical and have encouraged rapid advancement in research. Several surveys of research have been done in the past, so emphasis is placed on the newest and most innovative research. In particular, the advancement of research on active noise control during the decade of the eighties is reviewed.
This paper presents adaptive parameter identification results for a complex flexible structure with many closely packed natural frequencies. Least-squares lattice filters, which are recursive in both time and order, a...
详细信息
The paper presents an adaptive control algorithm for unknown time-varying systems having purely deterministic time-varying disturbances. The algorithm is an extension of the author's earlier work on adaptive contr...
详细信息
The paper presents an adaptive control algorithm for unknown time-varying systems having purely deterministic time-varying disturbances. The algorithm is an extension of the author's earlier work on adaptivecontrol of deterministic time-varying systems. It is shown that global convergence of the algorithm depends on the observability of a time-varying system. Simulation results are also given to illustrate the ability of this algorithm in tracking both time-varying disturbances and parameters
暂无评论