Adaptive control systems

A strategy for adaptive control and energetic optimization of aerobic fermentors was implemented, with both air flow and agitation speed as manipulated variables. This strategy is separable in its components: control, optimization, estimation. We optimized parameter’s estimation (from the usual KLa correlation) using sinusoidal excitation of air flow and agitation speed. We have implemented parameter’s estimation trough recursive least squares algorithm with forgetting factor. We carried separate essays on control, optimization and estimation algorithms. We carried our essays using an original computational simulation environment, with noise and delay generating facilities for data sampling and filtering.

Our results show the convergence and robustness of the estimation algorithm used, improved with use of both forgetting factor and KLa dead-band facilities. Control algorithm used in our work compares favorably with PID using the integrated area criteria for deviation between oxygen molarity and critical molarity (set point). Optimization algorithm clearly reduces energetic consumption, respecting critical molarity. Integration of control, optimization and adaptive algorithms was implemented, but future work is needed for stability. Methods were defined and implemented for stability improvement. We have implemented data acquisition and computer manipulation of air flow and agitation speed for actual fermentors.

Research activities of conference papers, journal papers and books since 2010. These research thrills are ignited in the University of Newcastle, UK. The main research publications have been in the Digital signal processing, the realization of DSP architectures in reconfiguration hardware platforms, e.g.FPGA, Adaptive control systems, identification of wireless communication channel, Parallel algorithms,  parallel architectures. These have been efficiently applied in fMRI recognition, Network security, wireless network identification and real-time critical applications.

International Journal of Instrumentation and Control Systems (IJICS) is a Quarterly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Instrumentation Engineering and Control Systems. The journal focuses on all technical and practical aspects of Instrumentation Engineering and Control Systems. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced instrumentation engineering, control systems and automation concepts and establishing new collaborations in these areas. Authors are solicited to contribute to this journal by submitting articles that illustrate research results, projects, surveying works and industrial experiences that describe significant advances in the Instrumentation Engineering

An understanding of vortical structures and vortex breakdown is essential for the development of highly maneuverable and high-angle-of-attack flight. This is primarily due to the physical limits these phenomena impose on aircraft and missiles in extreme flight conditions. Demands for more maneuverable and stealthy air vehicles have encouraged the development of new control concepts for separated flows. The goal of this paper is to describe experimental flow control techniques used to manipulate the vortical structures and vortex breakdown over slender delta wings at high angles of attack. The paper begins with a review of the experimental vortical flow control techniques implemented and tested over the past 50 years. Then it examines more closely two promising and different pneumatic flow control methods for the control of vortex breakdown over slender delta wings: open-loop, along-the-core blowing and periodic blowing, and suction along the leading edges. These studies were perform...

Gait training for individuals with neurological disorders is challenging in providing the suitable assistance and more adaptive behaviour towards user needs. The user specific adaptation can be defined based on the user interaction with the orthosis and by monitoring the user intentions. In this paper, an adaptive control model, commanded by the user intention, is evaluated using a lower limb exoskeleton with incomplete spinal cord injury individuals (SCI). A user intention based adaptive control model has been developed and evaluated with 4 incomplete SCI individuals across 3 sessions of training per individual. The adaptive control model modifies the joint impedance properties of the exoskeleton as a function of the human-orthosis interaction torques and the joint trajectory evolution along the gait sequence, in real time. The volitional input of the user is identified by monitoring the neural signals, pertaining to the user's motor activity. These volitional inputs are used a...

- In this paper, we present two approaches for the control of an inverted pendulum on a cart. First, we use a combination of a neural network and a simple algorithm, where the neural network is responsible for ranking the current states while the algorithm decides the ...

This paper presents the design and evaluation of a fuzzy logic traffic signal controller for an isolated intersection. The controller is designed to be responsive to real-time traffic demands. The fuzzy controller uses vehicle loop detectors, placed upstream of the intersection on each approach, to measure approach flows and estimate queues. These data are used to decide, at regular time intervals, whether to extend or terminate the current signal phase. These decisions are made using a two-stage fuzzy logic procedure. In the first stage, observed approach traffic flows are used to estimate relative traffic intensities in the competing approaches. These traffic intensities are then used in the second stage to determine whether the current signal phase should be extended or terminated. The performance of this controller is compared to that of a traffic-actuated controller for different traffic conditions on a simulated four-approach intersection.

The development of a pressure/temperature multi-sensor based on a combination of micro-electromechanical systems (MEMS) sensor technology, novel ceramic materials, high-temperature electronics, and advanced harsh-environment electronics packaging is discussed. The pressure/temperature multi-sensor enables unprecedented monitoring of propulsion, energy generation, and industrial systems. A multi-sensor approach will reduce control system weight and wiring complexity, design time, and cost. Multi-sensor control strategies do better than the single-sensor strategy on the basis of both to raise the accuracy and fault tolerance ability effectively. The resulting sensors and packaging can be manufactured at low cost and operate in corrosive environments, while measuring temperatures up to 2,552 ?F (1,400 ?C) with simultaneous pressure measurements up to 1,000 psi. The combination of a high-temperature, high-pressure-ratio compressor system, and adaptive engine technologies enables high ...

... in an opponent motor controller for adaptive load compensation and synergy formation D. Optimal control of machine set-up scheduling E. Vector ... (1992) Construction of neural network classification expert ... In Proceedings of the international joint conference on neural networks. ...

Emerging military aerospace system operational goals, such as autonomy, will require advanced safety-critical control systems consisting of unconventional requirements, system architectures, software algorithms, and hardware implementations. These emerging control systems will significantly challenge current verification and validation (V&V) processes, tools, and methods for flight certification. Ultimately, transition of advanced control systems that enable transformational military operations will be decided by

This paper considers the analytic modelling of the voice coil actuated needle free jet injection. It first investigates the currently existing model for the injection and making some alterations based on the system behavior and basic definitions in physics. These alterations yielded a new set of equations which were solved using the Runge-Kutta-Felberg formular. Second order, forth order and fifth order curve fitting of the numerical model were performed in order to develop a polynomial that gives the direct non-differential pressure-time relationship for the needle free jet injection (developed, to the best knowledge of the authors, for the first time). This fifth order polynomial presented the least error, measured by the least of the norm of residuals. The model for the voice coil activator was developed by writing force balance equations based on Newton’s second law of motion. The transfer function of the motor was then used to investigate the behavior of the voice coil actuator...

Multivariable control laws are designed for the Advanced Fighter Technology Integration F-16 (AFTI/F-16). Both fixed gain and adaptive Proportional plus Integral (PI) controllers are designed for a plant were the number of outputs are not equal to the number of inputs (rectangular ...

Abstract : An automatic control system capable of controlling an unknown nonlinear system is designed using a direct adaptive control scheme, implemented with a Hopfield network. The application of this method to an arbitrary system is discussed in detail and three specific simulation studies are included. These studies include the implementation of the Hopfield network based direct adaptive control system to a linear system, an inverted pendulum, and a nonlinear model of the NPS Autonomous Underwater Vehicle (AUV) with six degrees of freedom. The AUV simulation includes a three dimensional trajectory following algorithm and shows the ability of the Hopfield network to adapt to simultaneous ordered changes in the AUV's depth, speed, and course. Additionally, an analog circuit design is proposed which implements the automatic control scheme without the support of a microprocessor. The circuit was set up in SPICE and the simulation results as well as some limitations of the analog circuit implementation of the Hopfield network are presented.

Abstract : The thesis addressed the control system development for a high-speed surface vessel. In particular, the work utilized modern adaptive control techniques to design a speed following controller for the SeaFox ASV; the vehicle features three distinct speed, regimes including the displacement, rapid transition and planing regimes. The study started with the collection of experimental data required to characterize the operating modes and the inherent nonlinear phenomena of the high-speed ASV. Then, it proceeded to system identification study with an objective to develop a mathematical model of the vehicle thus aiming to represent the ASV's speed dynamics at various regimes and to facilitate control system development. After completing the model development, three speed following controllers were designed: A classical Proportional-Integral-Derivative (PID), a nonlinear Model Reference Adaptive (MRAC) and a L1 Adaptive Controller. The motivation behind the choice of three different controllers is two-fold. First, comparison of the linear and nonlinear control approaches is desired to better illustrate the achievable control architecture limitations. Second, comparing two types of nonlinear adaptive control architectures allowed the selection of the best control algorithm for operating the ASV speed in the presence of highly non-linear dynamics and significant disturbances acting on it. Furthermore, each controller is integrated with the SeaFox mathematical model and implemented with and without realistic operational disturbances. This provided a basis for objective comparison among the controllers and gave a means to demonstrate their relative robustness and performance characteristics. Finally, the MRAC and the PID controller were implemented onboard the actual SeaFox ASV and tested in numerous sea-trials under natural conditions to once again demonstrate the advantages and limitations of the chosen control architectures.

: This dissertation describes the design of an adaptive controller for single-input single-output (SISO) systems with guaranteed bounds on the transient response, and robustness with external disturbances and unmodeled dynamics. Developed from a current approach called "L1 adaptive controller", we show that by adding two properly designed low pass filters at the input and at the estimator we can control the transient response and the sensitivity of the overall system to external disturbances and unmodeled dynamics. Global stability of the overall adaptive system is mathematically proven under the assumption that the system is minimum phase (i.e., with the zeros of the transfer function in the stable region) and bounds of the systems parameters are known to the designer. The extension of this approach to non-minimum phase systems, such as systems with flexible appendages, is also considered. We show that a non-minimum phase plant augmented with a properly designed parallel ...