Mujo Hebibovic

High performance disturbance observer based control of the nonlinear 2DOF helicopter system

This paper addresses the challenges of the disturbance observer (DOB) algorithms faced with highly nonlinear electromechanical systems which are dealing with high resolution and high speed operations. It describes the synthesis of robust and stable controllers and their applications in controlling azimuth and elevation angles of the helicopter model CE 150 supplied by Humosoft. Description of the helicopter, including its mechanical characteristics and mathematical model, is given in the paper. Tracking error, transient performances, power consumption and motor strains are used for the validation of control quality. Implementation of the control system on the experimental setup is also explained. MATLAB and Simulink are used as tools for developing the simulation model of the helicopter system. Obtained simulations are showing that developed controllers provide significantly improved results even in the presence of unknown and unpredictable inputs (disturbance and noise), unpredictable and unknown dynamics, external forces (torques) and change of the system parameters.

EVOLUTION OF PARAMETERS OF NONLINEAR POSITION CONTROL FOR DYNAMIC MODEL OF MOBILE ROBOT WITH FRICTION

Abstract In this paper, we propose two level control system for a mobile robot. The first level subsystem deals with the control of the linear and angular volocities using a multivariable PI controller described with a full matrix. The position control of the mobile robot represents the second level control, which is nonlinear. The nonlinear control design is implemented by a modified backstepping algorithm whose parameters are adjusted by a genetic algorithm, which is a robust nonlinear optimization method. The performance of the proposed system is investigated using a dynamic model of a nonholonomic mobile robot with friction. We present a new dynamic model in which the angular velocities of wheels are main variables. Simulation results show the good quality of position tracking capabilities a mobile robot with the various viscous friction torques.

On-line identification of a robot manipulator using neural network with an adaptive learning rate

Abstract This paper proposes an extension of neural network identification capabilities for on-line identification of a nonlinear closed-loop control system. The neural network (NN) is trained on-line using the backpropagation optimization algorithm with an adaptive learning rate. The optimization algorithm is performed at each sample time to compute the optimal control input. The results confirm the effectiveness of the proposed neural network based identification scheme and control architecture.

Synthesis of the integral sliding mode control and the robust internal-loop compensator for a class of nonlinear systems with matched uncertainties

This paper presents the design procedure of the integral sliding mode controller with enhanced robustness properties for a class of nonlinear uncertain systems. The integral sliding mode control (I-SMC) is synthesized with the generalized disturbance attenuation scheme called robust internal-loop compensator (RIC) through the Lyapunov redesign framework, thus introducing a generalisation of the well-known case for linear systems. The resulted two-layer control structure employs the classical controller with the feedforward term in the outer control loop to track the reference, while the inner control loop compensates the generalized disturbance and provides robust stability. The closed-loop system is proved to be asymptotically stable via Lyapunov stability theory. The developed control algorithm is used for attitude tracking of the small-scale helicopter system in the presence of additional parametric uncertainties and external disturbances. An excellent tracking performance and robustness stability of the proposed control method are revealed through computer simulations and experimental testing over the whole domain of the helicopter outputs.

Similarities in development of digital computers and mobile robots

This paper presents a history of development of digital computers, PCs, and experimental mobile robots. Criteria for forming performance indexes of experimental mobile platforms are defined. A comparison of feature of development of digital computers and experimental mobile robots are given. Effects of applications of PCs in mobile robotics are stressed, and certain future development of mobile robotics have been discussed.

PROCESS OF EDUCATION AND TRAINING IN DEVELOPING COUNTRIES AS AN ADAPTIVE SYSTEM OF CONTROL

Abstract Process of education and training in the countries all over the world is regulatedby law and founded on legal norms and standards. Process of education and training is prograrmned to provide knowledge for future, should be rational, cannot be considered as independent and has to be based on the worlds standards of quantity and quality of knowledge given. Developing cOlmtries especially have to maintain and pursue clearly defined goals to be achieved, as well as guiding principles behind the system of education andtraining. It is convenient to observe the process of education and training, in developing countries, as an adaptive system of management with a reference model, where the reference model could be selected among some of the worlds leading centres (universities, research centres etc) for the process of education and training, in the same field and profession. In developing countries, the process of education and training has to be an adaptable system, upon which an influence can be exercised, through the mechanism of adaptation. It is important that the evaluation of the process of education and training in developing countries is done in objective and unbiased manner, and necessary changes in the process of education and training suggested.