Haider A. F. Mohamed

Modelling and PID controller design for a quadrotor unmanned air vehicle

This paper presents the modelling of a four rotor vertical take-off and landing (VTOL) unmanned air vehicle known as the quadrotor aircraft. The paper presents a new model design method for the flight control of an autonomous quad rotor. The paper describes the controller architecture for the quadrotor as well. The dynamic model of the quad-rotor, which is an under actuated aircraft with fixed four pitch angle rotors, will be described. The Modeling of a quadrotor vehicle is not an easy task because of its complex structure. The aim is to develop a model of the vehicle as realistic as possible. The model is used to design a stable and accurate controller. This paper explains the developments of a PID (proportionalintegral-derivative) control method to obtain stability in flying the Quad-rotor flying object. The model has four input forces which are basically the thrust provided by each propeller connected to each rotor with fixed angle. Forward (backward) motion is maintained by increasing (decreasing) speed of front (rear) rotor speed while decreasing (increasing) rear (front) rotor speed simultaneously which means changing the pitch angle. Left and right motion is accomplished by changing roll angle by the same way. The front and rear motors rotate counter-clockwise while other motors rotate clockwise so that the yaw command is derived by increasing (decreasing) counter-clockwise motors speed while decreasing (increasing) clockwise motor speeds.

Geometrical approach of planar hyper-redundant manipulators: Inverse kinematics, path planning and workspace

A new method for inverse kinematics for hyper-redundant manipulators is proposed in this paper to plan the path of the end-effector. The basic idea is that for a given smooth path consisting of points close enough to each other; computing the inverse kinematics for these points is carried out geometrically using the proposed method. In this method, the angles between the adjacent links are set to be the same, which makes lining up of two or more joint axes impossible; therefore, avoiding singularities. The manipulability index has been used to show how far the manipulator from the singularity configuration is. The determination of the workspace of the manipulator using the proposed method has been presented in this paper. The simulation results have been carried out on a planar and a three dimensional manipulators. The effectiveness of the proposed method is clearly demonstrated by comparing its result with results calculated by the well-known method of measuring manipulability which is used for singularity avoidance for the last two decades.

Power system stabilization based on artificial intelligent techniques; A review

This paper reviews new approaches in modern research using Artificial Intelligent (AI) techniques to develop power system stabilizer (PSS). These techniques are Artificial Neural Network (ANN), fuzzy logic, hybrid artificial intelligent, expert systems, and optimization techniques base AI such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Tabu Search (TS) algorithm, etc. Research showed controllers designed based on a conventional control theory, modern and adaptive control theories, suffer from some limitations. However, AI techniques proved to be able to overcome theses limits. Hence, more researchers preferred to utilize these approaches for the power systems. The review efforts geared towards PSS and excitation system stabilizer developed based on AI techniques, which effectively enhance both small signal stability and transient stability and equally provide superior performances. In addition, the dynamic performance of different AI based stabilizers are established and compared with other types of PSSs.

Singularity avoidance of a six degree of freedom three dimensional redundant planar manipulator

This paper focuses on the improvement of singularity avoidance of three dimensional planar redundant manipulators by increasing its degrees of freedom without increasing the number of motors controlling the manipulator. Consequently, the method to build a three dimensional planar manipulator with six-degrees of freedom using three motors instead of six is discussed in detail. A comparison of the manipulability index values for the proposed manipulator is made with the manipulability index values of PUMA arm to demonstrate the effectiveness of using the proposed manipulator for singularity avoidance.

A geometrical inverse kinematics method for hyper-redundant manipulators

Hyper-redundant manipulators have large number of kinematic degrees of freedom, thus processing some unconventional features such as the ability to enter a narrow space while avoiding obstacles. To solve the problem of multi-solution caused by redundancy, a geometrical method is presented in this paper. This proposed method finds one optimal solution to the inverse kinematics of redundant or hyper redundant manipulators from these infinite solutions with fewer computations. This method can be used for any planar n-serial manipulators. Experiments are conducted 3-links redundant manipulator and 10-links hyper-redundant manipulator to demonstrate the effectiveness of this proposed method.

Motion planning of hyper redundant manipulators based on a new geometrical method

Motion planning capability is an essential part of an industrial robot system. Therefore research in robot motion planning remains as one of the important fields of study in the task of building industrial robot systems. A new method for the motion planning is presented in this paper. The basic idea is to find a smooth path consisting of points close enough to each other. Then the computation of the inverse kinematics for these points is accomplished with the help of a new proposed geometrical method to solve the problem of multi-solution caused by redundancy. The advantage of this method is that the angles between the adjacent links are the same, it makes controlling these links easier and the movement of the manipulator itself more stable. This method can be used for the equal length links planar manipulators. To demonstrate the effectiveness of this proposed method, experiments were conducted on a 10-links hyper redundant manipulator in this paper.

Artificial neural networks aided solution to the problem of geometrically bounded singularities and joint limits prevention of a three dimensional planar redundant manipulator

Abstract This paper presents a neural network based on a nonlinear dynamical control of a three-dimensional six degrees of freedom planar redundant manipulator. An artificial controller is used for the computation of fast inverse kinematics, and is effective on geometrically bounded singularities and joint limits prevention of redundant manipulators. A comparison between the results of a multilayer back propagation and the radial basis function neural network has been carried out, and the results show that the radial basis function of neural networks is more attractive due to their fast training, simplicity, and convergence rate. The radial basis function neural network has been used to estimate the centrifugal and gravitational effects of the joints, while the end-effector follows a desired path.

Model predictive control of an inverted pendulum

In this paper, model predictive control is applied to an inverted pendulum apparatus and the effect of input disturbance are studied. The optimization problem is solved on-line using quadratic programming approach on a PC hardware platform.

Indirect vector control of a variable frequency induction motor drive (VCIMD)

The principle of vector control of electrical drives is based on the control of both the magnitude and the phase of each phase current and voltage. Matlab/ Simulink has been performed for assessment of operating features of the proposed scheme. PI speed controller are designed in this paper, Test response of the developed variable speed drive along with simulated response are given and discussed in detail for torque, speed and current. Modeling of induction motor with the complete vector control scheme (indirect) is investigated to show the optimal response of the control system.

Redundant manipulators kinematics inversion

A robotic system is kinematically redundant when it possesses more degrees of freedom than those required to execute a given task. This paper reviews the well-known methods used to find the inverse kinematics of redundant manipulators. Because redundant manipulators have infinite solutions for their inverse kinematics, therefore the conventional method that was used to calculate the inverse kinematics of non-redundant manipulators cannot be used. The methods used to calculate the inverse kinematics of redundant manipulators are divided into three main categories in this paper: pseudoinverse, artificial intelligence and geometrical methods. These types have been explained, their advantages and disadvantages are also discussed in this paper.