Department of Electrical Engineering
http://hdl.handle.net/123456789/16
2017-12-15T10:24:18ZOutput Feedback FTC Scheme for Linear Parameter Varying Systems
http://hdl.handle.net/123456789/617
Output Feedback FTC Scheme for Linear Parameter Varying Systems
Izhar Ul Haq, CIIT/FA13-MSEE-006/LHR
ABSTRACT:
The proposed research has been carried out for an Active Fault Tolerant Control (FTC) of Linear
Parameter Varying (LPV) systems using output feedback mechanism. Output feedback is a practical
approach due to the fact that all the plant states are not accessible or measurable,
therefore estimating the unknown states and maintaining the closed loop stability in an LPV
framework is closer to the control of nonlinear systems. At the same time, it utilizes the mature
nature of linear control theory.
In this research, LPV observers in LMI framework have been designed for affine LPV plant, using two
different LPV approaches namely affine and polytopic, in order to estimate the unknown states.
These estimated states are used as a feedback to LPV controller. Integral sliding mode controller
in LPV framework has been designed along with control allocation scheme to control the controlled
states as well as to counter for actuators faults and failures. It has been assumed that Fault
Detection and Isolation unit, also called FDI, is providing updated actuator faults or failures
information to the control allocation (CA) scheme.
Detailed performance and stability of the proposed control scheme has been checked in fault-free
case, i.e. nominal condition, as well as in the situation when actuator fault occurs. To validate
the proposed output feedback FTC mechanism, an LPV model of longitudinal plant of aircraft, taken
from the literature, has been considered as a benchmark in the simulation. The simulation results
show that the system is quadratically stable and give good tracking capability by the LPV
controller-observer pair in nominal as well as in actuatorâ€™s fault or failure situation.
2017-06-30T00:00:00ZAttitude Control of Satellite Using Computationally Efficient Model Based Predictive Control Techniques
http://hdl.handle.net/123456789/609
Attitude Control of Satellite Using Computationally Efficient Model Based Predictive Control Techniques
Muhammad Shah Rukh Ahmad, CIIT/FA12-MSEE-011/LHR
ABSTRACT:
Attitude control System (ACS) of spacecraft performs the attitude control to counter the effects of
disturbances present in the space environment. MPC (Model Predictive Control), controller is a
control algorithm which uses the mathematical model of the plant and also considers input and
output constraints for the calculation of optimal control law in real-time. The issues with the
conventional MPC are its computational time and feasibility at each sampling instant. The larger
computational time and infeasible optimization solution in real-time applications is a cause
of concern. Previous work has only considered the implementation of MPC by considering the inputs
constraints. The use of MPC to consider output constraints and effect of feasibility and
computation time has not been explored. Therefore computationally efficient two variant algorithms
of MPC i.e., Optimal MPC (OMPC) and Laguerre OMPC (LOMPC), have been selected as control algorithms
to study feasibility and computational time by linking dual mode, closed-loop paradigm and Laguerre
function techniques for linear and non-linear model. Linear model approximates non-linear model
because of small angle approximations. Also changes in satellites attitude angles because of
disturbances fall in the domain of small angles approximation regions. The effect of changing the
position of Laguerre Poles on the closed loop performance and computation time was explored. The
input constraints were considered on the control torque, whereas output constraints were considered
for roll, pitch and yaw angles. The conclusion is that the in the case of linear approximated
model, use of OMPC algorithms with Laguerre functions improves computational time. Both OMPC and
LOMPC do not affect the closed loop performance even if infeasible solutions are produced. When
OMPC and LOMPC algorithms were applied to the non-linear model, diverging non-zero steady-state
errors were introduced and plant became unstable. It was evident from the results that OMPC and
LOMPC were not able to control the non-linear model.
2017-06-30T00:00:00ZDesigning of NC-OFDM Transceiver for Cognitive Radio
http://hdl.handle.net/123456789/564
Designing of NC-OFDM Transceiver for Cognitive Radio
Muhammad Awais DDP-SP12-BTE-042 Muhammad Arif DDP-SP12-BTE-040, Tariq Manzoor DDP-SP12-BTE-086 Rana Mohsin Ashraf DDP-SP12-BTE-066
With the advancement in the use of wireless technology the maximum utilization of the frequency spectrum is becoming challenging. Cognitive Radio is one of the solutions that has been introduced to achieve this objective. Cognitive Radio or the spectrum sensing/sharing is the technique in which the free spectrum is sensed and then allocated to the secondary users. Using this idea a transceiver could be designed that has a sensing power for the spectrum. The Non-contiguous Orthogonal Frequency Division Multiplexing (NC-OFDM) can be used for the modulation of the signal. It could be implemented by applying the concept of Neural Networks (NNs) on the subcarriers of OFDM. The neural network takes the OFDM spectrum as an input and performs the task of activation and deactivation of the subcarriers. In this way it senses the spectrum and provides the subcarriers that are free from interference. The NNs produce much accurate results as compared to other sensing techniques. An NN basically converts the OFDM to NC-OFDM. Such an NC-OFDM transceiver would be an efficient and improved solution to the problem. So, this would help to achieve the maximum usage of the spectrum that is allocated to a user
2015-06-16T00:00:00ZVehicle Make and Model Recognition through Wireless Multimedia Sensors Network
http://hdl.handle.net/123456789/563
Vehicle Make and Model Recognition through Wireless Multimedia Sensors Network
Mohid Pirzada DDP-Sp12-BTE-037 Hur Malik DDP-Sp12-BTE-029, Usman Anwer DDP-Sp12-BTE-093
This project is intended to detect make and model of vehicles entering an educational or commercial institute to assist in provision of security and surveillance through the use of multimedia sensors nodes deployed at strategic positions. The sensed images are processed to
extract object features for comparison with available vehicles database. The developed application is also able to extract and share the best frame from live feed to the centralized security management software. This project also performs vehicle logo and colour detection and
is able to work in both controlled and uncontrolled environment. With good detection accuracy, real time video processing capabilities and low cost, the system is ideal for enhancement of security and surveillance in educational institutes of Pakistan
2015-12-10T00:00:00Z