Applied Mechanics and Materials Vols. 278-280

Abstract: In recent years, with the increasing of wind farm's capacity, requirements of the ability of fault ride through for wind farm are getting more and more stringent. The article analyzes the methods improving the low voltage ride through capability of the constant speed constant frequency wind power generation system. Static Synchronous Compensator (STATCOM) and Series Dynamic Breaking Resistor (SDBR) have recently been reported as stabilization methods for fixed-speed wind generator systems. Simulation results demonstrate that the STATCOM is a cost-effective solution for transient stability enhancement and minimization of voltage fluctuations, while the BR is the simplest in structure and a cost-effective solution for transient stability enhancement. Then a method is prompted, which Combines STATCOM and SDBR to promote the fault ride-through ability of constant speed constant frequency wind power system. By this way, the system validity and stability can be improved while costs can be cut down.

Abstract: The automated guided vehicles (AGVs) dispatching problem has been addressed to a large extent in literature.most of vehicle dispatching rules used in literature are single-attribute dispatching rules and sensitive to the facility layout.In this research, a new multi-attribute dispatching rule is proposed for AGVs and compare its performance with that of two of the best dispatching rules in literature.Using simulation, we prove that the new multi-attribute dispatching rule perform well and is robust under different working conditions.

Abstract: The damping force of Magnetorheological damper (MRD) can be controlled in a certain range by applying a steady magnetic field to reduce vehicle suspension vibration effectively. This paper presents the analysis of the damping characteristics of the twin-tube MRD, and the design of embedded control system for Twin-tube MRD used to semi-active vehicle suspension. The laws of varying damp force with current, displacement and frequency are investigated by testing for the damper, for instance the relationship curve of damping force vs. current. The control system is composed of controllable current driver and electrical control unit (ECU). ECU is developed based on MC9S12XDP512 chip. Signals that ECU acquired come from three types of sensor, i.e. digital temperature sensor, MEMS acceleration sensor and laser distance sensor embedded in MRD. The sampling frequency may exceed 400Hz. The programming is carried out in accordance with the state data acquisition and the improved On-Off control algorithm．Aiming at the high time response requirement of the MR damper, a Pulse-width modulation (PWM) current driver was designed. The hardware solutions drive circuit, interface circuit as wel1 as the software design of control system are discussed in detail. The proposed designed system has been put in actual MRD controlling application, whose test results prove its fast current response and high precision.

Abstract: NC machine tools are generally thought to be with a high degree of automation, high precision, high reliability and high efficiency characteristics. But because of the inherent flaws of the machine mechanical structure, such as screw wear, assembly errors or repeated positioning error, the machining accuracy may reduce. Therefore, this paper describes a self-compensating system design FPGA-based NC machine tools. Using Programmable devices(FPGA) and Hardware description language(VHDL) to achieve self-compensation system controller development, Position measurement from absolute encoder in real-timing, Comprehensive building of NC machine tools since compensation control system.

Abstract: This paper presents the new method of generating the trajectory at every cycle using PVAJT data, where P means the position, V the velocity, A the acceleration, J the jerk, and T is the multiplied cycle time. This method reduces the calculation time in the trajectory planner so that it takes less time to generate more complex trajectory. Several path trajectories are realized by the PVAJT algorithm to show the performance of proposed method.

Abstract: In industrial machinery units in which handle with high loads, hydraulic actuators are often used to actuate the manipulators. The nonlinear effects of the hydraulic system can be a problem if they disturb the energy efficiency of the hydraulic system. In this study, a designed Adaptive neuro-fuzzy Controller for electro-hydraulic system is developed to reduce the energy consumption. An intelligent neuro-fuzzy controller is employed to optimize the quantitative energy of fluid power flow of hydraulic system by the rotation of the electric motor via an inverter. Results of experiment study are presented showing the potential improvement in term of energy saving and pressure servo performance offered by this method.

Abstract: It is crucial to control the engagement of the in-coming clutch and the disengagement of the off-going clutch for the gear-shift process in order to improve the shift quality of dual clutch transmission (DCT). Aiming at the development of a 6 speed wet-type DCT, three evaluation indices of shift quality including shift time, shift jerk and friction work per unit area, were analyzed in detail. And the torque and the engine speed control strategies for the upshift and the downshift processes were discussed respectively through dividing the gear-shift process into 5 stages. The proposed strategies have been evaluated via simulation experiments of the upshift from gear position 1 to gear position 2 and downshift from gear position 2 to gear position 1, under wide-open throttle respectively. The results show that the proposed strategies can get short shift time and acceptable ride comfort, meanwhile prolong the service life of the friction elements of dual clutches.

Abstract: This research aims to control the heading of a small RC helicopter based on fuzzy logic control approach. Control of such a vehicle is normally nonlinear system. To be linear system, the mathematical model of this system would be archived and its parameters. From such difficulty of obtaining mathematical model and parameters, thus in this propose we develop the heading control of a small RC helicopter by using fuzzy logic control, which is overcome the unmodeling of such vehicle, for objective of developed control system. The performance of system is specified to control in time domain design specification. The rule based construction for designing the fuzzy system is related to input and output membership function for inference fuzzy system. Second order response time is specified, and error e and delta error (e) are conditionally assigned for constructing the rule of fuzzy inference system using Mamdani reasoning scheme. Defuzzification method applies the center of gravity (COG) method to computation the output to compensate the error and delta error signal. Finally the result of experiment reveals that the tracking of control of desire heading command and feedback signal is archived via the desired control performance in heading control of a small RC helicopter system.

Abstract: New methods of the synthesis of multi-dimensional robust and adaptive control systems for the centralized control of the spatial motion of autonomous underwater vehicles (AUV) is developed in this paper, such as variable structure system (VSS) and self-adjustment system with reference model. The conditions of the sliding mode existence and the self-adjustment process stability with the presence of essential dynamic reciprocal effect between all control channels are obtained and strictly proved. The application of synthesized discontinuous control provides the high control quality at any variations of the object parameters within the given ranges.

Abstract: Three-phase active power filter (APF) is a typical switched affine system for the action of the power switch. The conventional method of modeling was based on the linear system theory. In this paper, a novel control procedure for the three-phase APF based on the switched affine system and quadratic stability is proposed. Firstly, the three-phase APF is built as switched affine system model. Based on the sufficient condition for quadratic stability of convex combination, the common Lyapunov function is selected. Then, the switched rules can be defined to assess quadratic stability of the switched system, thus realizing the control of the compensation current and the DC side voltage. Finally, simulation results have good agreement with the theory analysis, and demonstrate the validity of this approach.