Cooling panel wall system with difference types of cooling mediums

Global warming has caused worldwide average surface temperature to rise about 0.74oC during the past 100 years, which is partly aggravated by air-conditioning that releases chlorofluorocarbons (CFCs) and forming a vicious cycle. This paper proposes a cooling house system that can promote thermal comfort in buildings without air-conditioning. The cooling panel wall forms a part of an Integrated Building System (IBS), and is essentially made of tubes filled with either water or glycerin as the coolant. Target strength for the panel wall was designed based on the Malaysian Standard (MS) while the building ventilation system followed the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) standard. The results are reported based on indoor and outdoor temperature difference together with relative humidity to identify the best performing house model and also coolant. The outcome of this research is expected to add value to heritage house design concepts with a better promotion of air flow and circulation in the building, without over-usage of natural resources and higher building cost to achieve the same objective

Chattering reduction effect on power efficiency of ifoc based induction motor

Nowadays, the strategies to control Induction Motor (IM) is growing fast. The vector control strategies give better performance than the scalar control to control IM. IFOC is one of the vector control strategies which more realistic to apply in industry, military, and transportation. However, IFOC requires Sliding Mode Control (SMC) with the Lyapunov function to ensure robustness and stability. The first-order SMC or ordinary SMC uses boundary layers technique such as the saturation function and the tangent-hyperbolic function to overcome the chattering phenomenon. The performance of boundary layer is analyzed in rotor speed response, stator current response in dq0 frame and power performance. In rotor speed response, the SMC with and without boundary layer has error steady-state less than 2%. In stator current response with dq0 frame, the boundary layer with tangent-hyperbolic function has the best performance. The power analysis shows that the boundary layer with saturation function has an active power loss of 39.16%, reactive power loss of 23.37% and apparent power loss of 30.30%. The boundary layer with tangent-hyperbolic functions has the best performance in reducing power consumption with active power loss of 41.24%, reactive power loss of 24.78% and apparent power loss of 31.96%

Variable structure control with chattering reduction of a generalized T-S model

In this paper, a fuzzy logic controller (FLC) based variable structure control (VSC) is presented. The main objective is to obtain an improved performance of highly non-linear unstable systems. New functions for chattering reduction and error convergence without sacrificing invariant properties are proposed. The main feature of the proposed method is that the switching function is added as an additional fuzzy variable and will be introduced in the premise part of the fuzzy rules; together with the state variables. In this work, a tuning of the well known weighting parameters approach is proposed to optimize local and global approximation and modelling capability of the Takagi-Sugeno (T-S) fuzzy model to improve the choice of the performance index and minimize it. The main problem encountered is that the T-S identification method can not be applied when the membership functions are overlapped by pairs. This in turn restricts the application of the T-S method because this type of membership function has been widely used in control applications. The approach developed here can be considered as a generalized version of the T-S method. An inverted pendulum mounted on a cart is chosen to evaluate the robustness, effectiveness, accuracy and remarkable performance of the proposed estimation approach in comparison with the original T-S model. Simulation results indicate the potential, simplicity and generality of the estimation method and the robustness of the chattering reduction algorithm. In this paper, we prove that the proposed estimation algorithm converge the very fast, thereby making it very practical to use. The application of the proposed FLC-VSC shows that both alleviation of chattering and robust performance are achieved

Integral Action for Chattering Reduction and Error Convergence in Sliding Mode Control

Sliding mode control is a standard approach to tackle the parametric and modeling uncertainities of a non-linear system. However, the robust control obtained by using sliding mode has a price, which is the high frequency chattering encountered during the digital implementation of the control. The idea of introducing a boundary layer around the switching surface and approximating a continuous control inside it has been extended for different kinds of systems. The systems should be analyzed to ascertain which continuous law is appropriate within the boundary layer. In this paper the effect of various continuous control approximations within the boundary layer to chattering and error convergence in different systems is studied

Chattering Reduction and Error Convergence in the Sliding-mode Control of a Class of Nonlinear Systems

To reduce chattering in sliding-mode control, a boundary layer around the switching surface is used, and a continuous control is applied within the boundary. The effects of various control laws within the boundary layer on chattering and error convergence in different systems are studied. New functions for chattering reduction and error convergence inside the boundary layer are proposed which are discontinuous in magnitude but not in sign. The internal model principle has been used to generalize the design for the class of nonlinear systems being considered

Attitude tracking of a tri-rotor uav based on robust sliding mode with time delay estimation

The paper presents a robust sliding mode with time delay estimation method for controlling the attitude of a tri-rotor unmanned aerial vehicle (UAV) in presence of uncertainties and disturbances. The proposed control algorithm allows high accuracy tracking since a good disturbance estimation is provided using time delay estimation method and allows chattering reduction. The stability analysis of the closedloop system is presented using the theory of Lyapunov. Finally, two numerical simulations are presented in the presence of disturbances to show the effectiveness of the proposed nonlinear control scheme.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI

Independent modal variable structure fuzzy active vibration control of thin plates laminated with photostrictive actuators

AbstractPhotostrictive actuators can produce photodeformation strains under illumination of ultraviolet lights. They can realize non-contact micro-actuation and vibration control for elastic plate structures. Considering the switching actuation and nonlinear dynamic characteristics of photostrictive actuators, a variable structure fuzzy active control scheme is presented to control the light intensity applied to the actuators. Firstly, independent modal vibration control equations of photoelectric laminated plates are established based on modal analysis techniques. Then, the optimal light switching function is derived to increase the range of sliding modal area, and the light intensity self-adjusting fuzzy active controller is designed. Meanwhile, a continuous function is applied to replace a sign function to reduce the variable structure control (VSC) chattering. Finally, numerical simulation is carried out, and simulation results indicate that the proposed control strategy provides better performance and control effect to plate actuation and control than velocity feedback control, and suppresses vibration effectively

STABILITY AND PERFORMANCE OF NETWORKED CONTROL SYSTEMS

Network control systems (NCSs), as one of the most active research areas, are arousing comprehensive concerns along with the rapid development of network. This dissertation mainly discusses the stability and performance of NCSs into the following two parts. In the first part, a new approach is proposed to reduce the data transmitted in networked control systems (NCSs) via model reduction method. Up to our best knowledge, we are the first to propose this new approach in the scientific and engineering society. The "unimportant" information of system states vector is truncated by balanced truncation method (BTM) before sending to the networked controller via network based on the balance property of the remote controlled plant controllability and observability. Then, the exponential stability condition of the truncated NCSs is derived via linear matrix inequality (LMI) forms. This method of data truncation can usually reduce the time delay and further improve the performance of the NCSs. In addition, all the above results are extended to the switched NCSs. The second part presents a new robust sliding mode control (SMC) method for general uncertain time-varying delay stochastic systems with structural uncertainties and the Brownian noise (Wiener process). The key features of the proposed method are to apply singular value decomposition (SVD) to all structural uncertainties, to introduce adjustable parameters for control design along with the SMC method, and new Lyapunov-type functional. Then, a less-conservative condition for robust stability and a new robust controller for the general uncertain stochastic systems are derived via linear matrix inequality (LMI) forms. The system states are able to reach the SMC switching surface as guaranteed in probability 1 by the proposed control rule. Furthermore, the novel Lyapunov-type functional for the uncertain stochastic systems is used to design a new robust control for the general case where the derivative of time-varying delay can be any bounded value (e.g., greater than one). It is theoretically proved that the conservatism of the proposed method is less than the previous methods. All theoretical proofs are presented in the dissertation. The simulations validate the correctness of the theoretical results and have better performance than the existing results