To prevent the loss of data or distortion of the real sent data in the secure communication, the disturbance and uncertainty rejection is very important technique. Especially, the secure communication of the chaotic system, where the master and slave systems are used to encrypt and decrypt the signal. These systems are should be a chaotic. The chaotic system is unpredictable and unstable. The security is obtained if the master and slave systems are synchronizing. Therefore, this paper proposes a new disturbance observer (DO) for estimating attacked signals on public channels and uncertain values of the secure communication system (SCS). First, a new condition of the reaching law was proposed via a homogenous stability condition, which was used to construct the disturbance observer and synchronization controller. Second, the proposed stability is applied to design a new DO for estimating the attacked signals on the public channels and the variations of the parameters of all master and slave systems (MSSs). Third, the MSSs were synchronized by the sliding mode control (SMC) with the same reaching law with the proposed DO. The calculations of controller and observer designs were based on the Takagi-Sugeno fuzzy (TSF) system, where the MSSs were taken into account as the fuzzy system. However, the TSF was used for calculation only. The original chaotic of MSSs were used to keep the characteristics of the chaos phenomenon. Final, the mathematically proven was provided to show the corrections of the proposed methods. To show the superior powers of the proposed method, the simulation of MATLAB software and experiment of local network via the internet router were used to conduct the logical analysis. The tested disturbances and uncertainties were mostly compensated by the proposed DO.
A magnesium alloy AZ31 as plate of dimensions (60 x 60 x 3) mm has been constrained groove pressed (CGP) four deformation passes (16 pressings) at 250 oC by simulation and expremental. On the basis of the analysis of calculation results about the deformation distribution in the alloy AZ31 workpiece the mechanism for its microstructure evolution during the severe plastic deformation (SPD) process was partly clarified. On the other hand, deformation heterogeneity distribution developed in plate by applying CGP caused the evolution of a non-uniform microstructure. The TEM microstructure analysis results provided clear evidence that across the plate both the banded deformed microstructure where dislocation cell structure and/or partially or fully recovered polygonized subgrain microstructure are present. The recovering dynamic and local polygonization process contributes significantly to the formation of ultra-fine materials (UFG) microstructure.
A slotless self-bearing motor (SSBM) is a new type of electric motor, with its levitating and rotating capability as a drive system. In the design of motor, the iron core of stator was removed, it could have many advantages such as small size, light, no friction loss, low losses, high speed. Besides, disturbance and uncertainty factors are the unexpected values, which impacting strongly to the output of the control system. In this paper, to reject the effects of these factors, an optimal Lyapunov-based (OLB) sliding mode control (SMC) was proposed to control the movements and rotation of SSBM system. First, the mathematical model with uncertainty and disturbance factors of the SSBM system was rewritten to show the detail configuration of the proposed motor. Second, the OLB-SMC controllers were designed for the control of displacements on x−, y- axes, rotor speed on ω− axes, respectively. Third, the stability analysis of control algorithm was demonstrated via the Lyapunov stability theory. Finally, the experimental test was implemented to prove the high performance of the OLB-SMC for SSBM system. The practical results show that the effectiveness of OLB-SMC controller for SSBM system. The novelty of the proposed method is that the stability condition was newly proposed based on the transformation from scalar equation to state-space equation, where the gains of controller were found based on the linear matrix inequality.
As well know, the use of high technology is more and more encouraged in many countries to decrease the costs, time, and human resources. This paper presents a speed control of brushless DC motor (BLDC), which was applied for the smart storage cabinets. BLDC motor is proposed due to its low costs, high torque, and high performance. The proportional-integral (PI) controller is constructed for the speed control of the movement of cabinet systems. First, the mathematical model and transfer function of the BLDC motor is rewritten to show the structure of the BLDC motor. Second, the proposed PI controller is designed based on the tuning Ziegler-Nichols method and the PI controller is also expressed by the discretized form for BLDC motor. Third, the working principle of BLDC motor is clearly represented and analyzed. Forth, the detail configuration of the experimental system is presented. The STM32 microcontroller unit (MCU) was used to execute. Finally, the experimental test was implemented to validate the power of the proposed controller in practical cases. The experimental results at no-load and load were shown that the power of proportional integral derivative (PID) controller is good at tracking the desired speed signals.
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