Applied Mechanics and Materials Vol. 598

Abstract: The main purpose of this study is to prepare mathematical model for active vibration control of a structure. This paper presents the numerical and experimental modal analysis of aluminum cantilever beam in order to investigate the dynamic characteristics of the structure. The results will be used for active vibration control of structure’s experimental setup. Experimental natural frequencies are obtained and compared to verify the proposed numerical model by using modal analysis results. MATLAB System Identification Toolbox and ANSYS harmonic response function are used together to estimate beam’s equations of motion which include its amplitude, frequency and phase angle values. Moreover, the mathematical model of beam is simulated in MATLAB/Simulink software to determine the dynamic behavior of the proposed system. Furthermore, another prediction model approach with multiple input and single output is used to find the realistic behavior of beam via an adaptive neural-network-based fuzzy logic inference system, in addition, impulse responses of the proposed models are compared and the control block diagram for active vibration control is implemented. As a first iteration, PID type controller is designed to suppress vibrations against the disturbance input. The results of modal analysis, the prediction models, controlled and uncontrolled system responses are presented in graphics and tables for obtaining a sample numerical active vibration control.

Abstract: Vibration suppression is a major problem in various domains, with applications ranging from medical devices to aerospace engineering. Several methods for suppressing vibrations have been proposed, but very few address this issue from the fractional calculus perspective. The emerging new fractional order controllers have the ability to meet more design specifications at the same time, behaving robustly against modeling uncertainties, external disturbances, etc. In this paper, a new tuning method for fractional order PD^µ controller is proposed in which the design directly addresses the problem of suppressing resonance frequency vibrations. The case study consists in an unloaded smart beam. The simulation results, considering an additional situation of the loaded smart beam, show that the proposed method is simple and leads to a robust closed loop behavior.

Abstract: Manufacturing of spur gears on CNC machining centers and CNC wire cutting is randomly used due to the difficulty in producing the perfect gear profile. The present paper faces this problem by developing a special cycle that can be used on both types of machines. A code for this cycles is designed to read the part program of any product and if detects the code nominated for this cycle (G77) which indicates that a gear needs to be cut, it develops the geometrical statements of the gear profile and the motion statements. It follows by writing the full code of the cycle. The validity of the designed model was verified on a CNC simulator.

Abstract: Lower extremity exoskeletons are wearable robot manipulators that integrate human intelligence with the strength of legged robots. Recently, lower extremity exoskeletons have been specifically developed for rehabilitation, military, industrial applications and rescuing, heavy-weight lifting and civil defense applications. This paper presents controller design of a lower-extremity exoskeleton for a load carrying human to provide force feedback control against to external load carried by user during walking, sitting, and standing motions. Proposed exoskeleton system has two legs which are powered and controlled by two servo-hydraulic actuators. Proportional and Integral (PI) controller is designed for force control of system. Six flexible force sensors are placed in exoskeleton shoe and two load cells are mounted between the end of the piston rod and lower leg joint. Force feedback control is realized by comparing ground reaction force and applied force of hydraulic cylinder. This paper discusses control simulations and experimental tests of lower extremity exoskeleton system.

Abstract: This paper presents an application of the MRAC (Model Reference Adaptive Control) techniques to achieve the attitude stabilization in an unmanned aerial vehicle (UAV) type quadrotor when there exists disturbances and/or uncertainties in the parameters due to changes in the payload, variations in battery voltage during flight, etc. This is achieved by performing an online adaptation of the controller parameters, which are obtained by showing the stability property of the closed loop control system using Lyapunov theory. Simulation results using Matlab-Simulink platform are presented to demonstrate the convergence of the controller parameters.

Abstract: In order to effectively solve the problem of selection trajectories of flight vehicles, some pseudo-intelligent systems with functional structures were established. Moreover, systemogenesis of pseudo-intelligent control systems of flight vehicles was illustrated. Based upon the theory of P.K. Anoxin functional systems and self-organization algorithms, the perspective pseudo-intelligent control systems for all stages of systemogenesis can make a reality of the whole-life control of flight vehicles.

Abstract: The aerodynamic performance of TAU0015 airfoil was investigated with synthetic jet control method. The simplified mathematical model of the active flow control was established with unsteady velocity boundary condition at the specific location of airfoil surface. The aerodynamic performance was simulated with synthetic jet and the efficiency of jet momentum coefficient was conducted. The result shows that the flow control model could perform the minor jet flow characteristics and higher jet momentum coefficient result better control efficiency.

Abstract: If the air conditioning usage situation cannot be effectively improved, the energy consumption process will be accelerated, exacerbating the energy crisis. Despite scientists’ efforts to find alternative energy sources to solve the energy crisis, the most immediate solution is to reduce energy consumption.In this study, the energy-conservation system was designed by setting up several temperature sensors, transfer modules, and water sprinklers on rooftops and external walls that were exposed to the most sunlight; the temperature sensor modules regularly measured the roof temperature and used radio frequency (RF) technology to transfer the temperature data to the indoor receiving set. The measured temperatures were then compared with the indoor temperatures, after which the monitor program analysed and sent commands to control and activate the water sprinkler system. This allowed timely sprinkling using the proper water amount to lower the surface temperature of the roofs and external walls, which also slightly reduces the indoor temperature, achieving energy-conservation objective. Actual examples were then used to investigate the energy-saving effectiveness of the proposed system.

Abstract: With the continuous development of CNC technology, its application is more and more extensive. In recent years, the application of CNC technology in the area of stage also made great achievements. This paper detailed a scientific and reasonable scheme of acrobatic stage machinery and its control part, using CNC technology in acrobatic stage, through the corresponding algorithm and software realizing the operation and control of any trajectory in 3D space, taking advantage of intelligent editing function of screen running track, and compared with the traditional acrobatic stage , it gets more flexible, stronger strain capacity.

Abstract: The power generation system using Organic Rankine Cycle (ORC) is a new technology for energy recovery, but very few people have studied the control system of the organic working fluid turbine at present. This paper put forward the speed and power control strategy about the organic working fluid turbine. The parameters of the speed and power regulators are tuned to insure the steady of speed and power. A series of dynamic simulation experiments are carried out in Simulink. Through the simulation research of robustness and load disturbance experiments, the designed control system have a good effect on accuracy and dynamic response.