Journal of Majlesi Journal of Mechatronic Systems
Volume:4 Issue: 3, Sep 2015

The aim of this study is to propose a control strategy on the basis of discrete-time sliding mode control, for control of ankle joint in paraplegia using functional electrical stimulation. Agonist-antagonist co-activation is used to control the ankle movement. In order to achieve this goal, first, the human is modeled as an inverted pendulum. Second, the nonlinear relationship between inclination angle and center of pressure is modeled. Finally, two discrete-time sliding mode controllers are used to stabilize the upright posture. The results indicate that the mentioned control approach is an effective way in paraplegia using functional electrical stimulation.

In this paper, simulated the kinematics modeling and Jacobian analysis of the six degrees of freedom of Stewart mechanism by pneumatic operators are discussed and a systematic method is provided for it. This article includes parts such as direct kinematics analysis and reverse-kinematics analysis. After the analysis of the kinematics of mechanism, the relevant equations were extracted; and finally, by the deriving from them in the time domain, the relationships between the different components of the system are expressed in the form of speed and Jacobian.

This paper addresses the output feedback trajectory tracking control problem of Ackerman steering-drive wheeled mobile robots under non-holonomic constraints in the presence of model uncertainties without velocity measurement. By determining a suitable set of output equations, an input–output model of wheeled mobile robots is developed, which helps the designer utilize the classic control algorithms of robot manipulators. A RBF neural network and a linear observer are employed to construct the controller for constrained robot with only position measurement. The proposed controllers employ saturation-type adaptive-neural control laws to effectively compensate for the uncertain parameters, unmodeled dynamics and unknown bounded disturbances. Lyapunov-based stability analyses are utilized to guarantee that tracking errors are uniformly ultimately bounded and exponentially converge to a small ball containing the origin. The simulation results are presented to illustrate the tracking effectiveness of the controller.

The purpose of the article is control of speed and starting current of a turbojet engine on the first step starting electrical. The controllers are designed to reduced peak of starting current to the minimum possible value. In this paper, special attention was devoted to engine speed during reducing starting current. So that reducing starting current is done by sliding control and fuzzy controller used for control startup speed. Fuzzy controller is responsible for regulating the coefficient of sliding controller but so that the speed at end of the first stage be not less than 1818rpm. Finally, reducing of current compared with no control and will observe dramatic reduction of starting current.

With the expansion of urban electric trains as a mean of public transport, electric train passengers expect trains to move faster and spend less time waiting at the stations. One of the most important factors in the early arrival of trains is headway or time distance between two trains. This cannot be reduced from the usual rate due to power quality and reliability as well as network security issues.In this paper, a 26-km railway power system has been simulated using MATLAB software and dynamic load flow of Newton - Raphson method. This test was conducted by decreasing train headway until voltage collapse occurs. As a result, the minimum train headway that causes the voltage collapse for this test system is 150 s. This confirms that the proposed algorithm can effectively be used to identify the point of voltage collapse in railway power systems.

This paper investigates the routing problem of motion robot. Routing was considered as offline, which means that the robot has complete information about environmental obstacles. Also, the motion environment was considered square and flat. Then it simulates the efficiency of two routing methods based on genetic and ant colony algorithms in MATLAB software environment. This research uses four experimental environments based on different complexities that their indexes are number and distribution of obstacles. It is expected that robot moves from source route to target route in static environment without contact with obstacles in minimum time and shortest route. We studied the efficiency of two algorithms for robot in moving time from source cell to target cell (in second), moved distance by robot from source point to target point(in meter) and arriving time to first answer(in second). The simulation results of two routing algorithms in the four mentioned environments are as follows:1) Routing robot based on genetic algorithm performed better than routing based on ant colony algorithm in moving time from source cell to target cell.2) Routing robot based on genetic algorithm performed better than routing based on ant colony algorithm in moving distance. 3) Both of routing method performed almost similar performance in finding the first answerexcept in one case.

Induction Motors are usually designed for the highest efficiency around their rated load. In most applications, the motor rating matches the worst-case load, but the motor frequently runs below rated conditions. As the load decreases the motor efficiency decreases and a larger percentage of the input power is in the form of losses. The motor efficiency can be improved by operating the motor at optimum flux by controlling the d-axis current in d-q reference frame in vector controlled drives. In this paper, Genetic Algorithm (GA) approach in decreasing losses of a 5 h.p induction motor is discussed and investigated. The strategies for decreasing the losses include adjusting magnetic current using electromagnetic torque and motor speed. Several simulations have been conducted to show the motor performance using GA. The results, when Genetic Algorithm is used for the induction motor in different load conditions, show a better performance.