Francisco R. Rubio

Self-tuning control of a solar power plant with a distributed collector field

A self-tuning proportional-integral controller for a solar distributed collector field that is based on a pole-assignment approach employing serial compensation to cope with measurable external disturbances is presented. The scheme is compared with the more commonly adopted parallel feedforward approach by both simulation and implementation on the plant itself.<<ETX>>

Fuzzy logic control of a solar power plant

This paper presents an application of fuzzy logic control to the distributed collector field of a solar power plant. The major characteristic of a solar power plant is that the primary energy source, solar radiation, cannot be manipulated. Solar radiation varies throughout the day, causing changes in plant dynamics and strong perturbations in the process. A special subclass of fuzzy inference systems, the TP (triangular partition) and TPE (triangular partition with evenly spaced midpoints) systems, is used to obtain adequate control signals in the whole range of possible operating conditions. The fuzzy logic controller has been tested in the real plant and results obtained are shown. A comparison with other control approaches widely used in the plant is performed using a nonlinear computer model of the field.

Backstepping/nonlinear H ∞ control for path tracking of a quadrotor unmanned aerial vehicle

This paper presents a nonlinear robust control strategy to solve the path tracking problem for a quadrotor unmanned aerial vehicle. The helicopter motion equations is obtained by the Lagrange- Euler formalism. The control structure is performed through a nonlinear Hinfin controller to stabilize the rotational movements and a control law based on backstepping approach to track the reference trajectory. Finally, simulations results in presence of aerodynamic moments disturbances and parametric uncertainty is carried out to corroborate the effectiveness and the robustness of the strategy proposed.

Application of a gain scheduling generalized predictive controller to a solar power plant

Abstract This paper presents a gain-scheduling generalized predictive controller for the distributed collector field of a solar power plant. The controller has been developed by considering CARIMA models of the field, calculated taking into account the frequency response of the plant. Aspects of the modelling, problems encountered and performance of the control scheme are dealt with and illustrated by plant results. A proven non-linear computer model of the collector field has been used to check the controller behaviour before its real implementation, and some simulation results are shown too.

Solar Energy Fundamentals

The use of renewable energy, such as solar energy, experienced a great impulse during the second half of the 1970s just after the first big oil crisis. At that time, economic issues were the most important factor and so interest in these types of processes decreased when oil prices fell. There is renewed interest in the use of renewable energies nowadays, driven by the need of reducing the high environmental impact produced by the use of fossil energy systems.

Stabilization of a class of underactuated mechanical systems via total energy shaping

In this paper a system of ODEs and a method for its solution are proposed for passivity-based stabilization of a class of underactuated mechanical systems. This method simplifies the PDEs imposed by the passivity-based control via interconnection and damping assignment (IDA-PBC) technique. For a class of mechanical systems satisfying some mathematical properties the PDEs are reduced to a simple set of nonlinear ODEs. A general solution for these equations in the 2-DOF case is presented, through a new parametrization of the closed loop inertia matrix. Two examples illustrate the method, achieving kinetic and potential energy shaping in a straightforward manner. The simulation analysis in comparison with recent studies highlight the advantages of these techniques.

Formation Control of Autonomous Underwater Vehicles Subject to Communication Delays

This paper addresses the formation control problem for fleets of autonomous underwater vehicles (AUVs). The solution is based on the virtual leader approach, with the main goal of designing a control system to cope with the inter-vehicle communication problems, especially significant in underwater environments. The use of kinematic relations allows the linearization of the AUV dynamics maintaining its turning capacities. The control strategy consists of a feedback H2/H∞ controller in combination with a feedforward controller, which makes it possible to deal with delays and packets dropouts while ensuring a good formation control performance.

Peduncular hallucinosis associated with posterior thalamic infarction

SummaryPeduncular hallucinations are generally associated with lesions of the midbrain. We describe a 68-year-old man who developed left hemiparesis, paraesthesias on the left side and vivid visual hallucinations, suggesting peduncular hallucinosis. MRI demonstrated a right posterior thalamic infarct as the sole lesion.

Differential coding in networked controlled linear systems

This paper investigates the closed-loop properties of the differential coding scheme known as Delta-modulation (A-M) when used in feedback loops within the context of linear systems controlled through some communication network. We propose a new modified scheme of the original form of the Delta-M algorithm which improves the closed-loop properties. The new coding structure explicitly uses information from the system model. Stability properties for both: the continuous-time and the discrete-time version of this new algorithm are assessed. The results shows that the stability domain and the resulting precision of the Delta-M is limited by the position of the unstable poles of the system

Dead-time compensation for ABR traffic control over ATM networks ☆

Abstract This paper presents a rate-based controller for throttling available bit rate (ABR) input rates in high speed asynchronous transfer mode (ATM) networks with significant propagation delays. First, a Smith predictor based controller is analyzed in terms of performance and stability. Saturation issues are handled with anti-windup techniques. Performance is improved by means of the feedback of an estimate of the ABR disturbance. This reduces the average queue level, guaranteeing the shortest delays possible while keeping the channel fully occupied. Finally, sensitivity to delay estimation errors is analyzed, and the limitations of the proposed controller are discussed.