Chala Merga - Academia.edu (original) (raw)

Chala Merga

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Pakistan Institute of engineering and applied science (PIEAS)

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Papers by Chala Merga

This paper proposes Robust PSO tuned FOSMC for altitude stabilization and trajectory tracking of ... more This paper proposes Robust PSO tuned FOSMC for altitude stabilization and trajectory tracking of agricultural monitoring UAV. First, the quadrotor dynamics are modeled using Newton-Euler formalism hybrid systems approach. Second, Fractional order sliding mode control system is developed for attitude and position trajectory tracking of quadrotorr system under unknown external disturbance. Quadcopter control algorism is divided into inner and outer control loops. The outer loop controls the position altitude and generates the reference trajectories of the orientation which is controlled in the inner loop. The inner loop controls attitude of the quadcopter. In order to achieve good task performance for agility, flying efficiency and trajectory tracking, particle swarm optimization (PSO) algorithms are used to obtain the parameters of fractionalorder sliding mode controller (FOSMC).

in this paper an interleaved DC/DC boost converter is compared with the conventional boost conver... more in this paper an interleaved DC/DC boost converter is compared with the conventional boost converter in order to design highly efficient and high performance converter for fuel cell application. Inductor current ripple, ripple in input/output voltage and efficiency of the converter is mainly studied and compared with the conventional boost converter. The simulation models have been developed and examined in the MATLAB/Simulink. The experimental results have demonstrated that the interleaved converter is more efficient than the conventional sort of boost converter topologies in order to achieving high performance, low ripple in input/output voltage/current for high power fuel cell application.

Electric Power Systems Research, 2017

The utilization of grid-scale energy storage is growing exponentially due its decreasing costs an... more The utilization of grid-scale energy storage is growing exponentially due its decreasing costs and added flexibility to providing numerous services. Among the currently available storage systems, batteries based on lithium-ion chemistries are poised to provide a significant share of such flexibility due to their high power and energy density, and relatively low cost per unit energy. However, research on such systems has been segregated into focus on its chemical properties, and focus on the grid integration separately. This paper proposes a data-driven framework to characterize battery energy storage systems embedded into a decision-making optimization model. The model embeds two mechanisms, variable Crates and variable efficiencies, so that batteries may be scheduled at high-power (high Crate) operations to capture additional grid revenues, only if economical against the cost of degradation effects. The framework is applied to stationary battery energy storage systems in retail markets in order to explore the improved energy arbitrage benefits.

Automatica, 1992

In this paper we present a robust adaptive control scheme for robot manipulators with time-varyin... more In this paper we present a robust adaptive control scheme for robot manipulators with time-varying parameters and unmodeled dynamics. Our scheme ensures that all signals in the closed-loop robot system are bounded and the tracking error is of the order of the parameter variations and unmodeled dynamics in the mean.