Semi-active Fuzzy Logic Controller Research Articles

Control of the air suspension system of semi-trailer trucks to enhance the road friendliness

An air suspension system of semi-trailer trucks controlled by semi-active fuzzy logic control is proposed and researched to reduce the dynamic load coefficient (DLC) of the wheel axles. A dynamical model described by a nonlinear system with 7-DOF of the vehicle and a Simulink program developed in Matlab software are applied to simulate the DLC values under different operation conditions. The fuzzy control is then applied to control damping coefficients of the air suspension system. The obtained results show that semi-active air suspension of semi-trailer truck is overall superior to passive air suspension. The DLC values are also significantly decreased in all cases of the road surface roughness, over a range of vehicle velocity and the different loaded conditions. Particularly, under vehicle fully loaded condition, the DLC value of the tractor driver is greatly reduced by 27.4 % at speed of 27.5 m/s on the ISO level B road.

Model-free fuzzy control of a magnetorheological elastomer vibration isolation system: analysis and experimental evaluation

This paper addresses the problem of micro-vibration control of a precision vibration isolation system with a magnetorheological elastomer (MRE) isolator and fuzzy control strategy. Firstly, a polyurethane matrix MRE isolator working in the shear-compression mixed mode is introduced. The dynamic characteristic is experimentally tested, and the range of the frequency shift and the model parameters of the MRE isolator are obtained from experimental results. Secondly, a new semi-active control law is proposed, which uses isolation structure displacement and relative displacement between the isolation structure and base as the inputs. Considering the nonlinearity of the MRE isolator and the excitation uncertainty of an isolation system, the designed semi-active fuzzy logic controller (FLC) is independent of a system model and is robust. Finally, the numerical simulations and experiments are conducted to evaluate the performance of the FLC with single-frequency and multiple-frequency excitation, respectively, and the experimental results show that the acceleration transmissibility is reduced by 54.04% at most, which verifies the effectiveness of the designed semi-active FLC. Moreover, the advantages of the approach are demonstrated in comparison to the passive control and ON-OFF control.

Semi-active Control of Building Structures using Variable Stiffness Device and Fuzzy Logic

Semi-active control devices, also called “Intelligent” control devices, constitute the positive aspects of both the passive and active control devices. A semi-active control strategy is similar to the active control strategy, but this control device has been shown to be more energy-efficient than active devices. A particular type of semi-active control device, the Variable Stiffness Device (VSD), consists of a hydraulic cylinder with a normally closed solenoid control valve inserted in the tube connecting the two cylinder chambers. This paper emphasizes on the application of Semi-active Fuzzy Logic Controller (SFLC) of this system for getting the best results in the reduction of the building responses under earthquake excitations. For the numerical example, a 12-story building, located in the city of Rasht, Iran, is modeled as 3-D frame and the problem is solved in state space. The results obtained from the proposed control scheme (SFLC) are compared with those obtained from the ON-OFF control method. It is found that the SFLC is highly effective in reducing the responses of the example building than the ON-OFF algorithm. In this study, the optimal values of the fuzzy rule bases, membership functions, and the location of the control device are determined.

Semiactive Fuzzy Logic Control of Suspension Bridge Flutter

A semiactive tuned mass damper (STMD) system with variable damping is used to control the flutter instability of long-span suspension bridges. For this purpose, a combined vertical and torsional model of a TMD system, which is placed at the middle of the center span, is used. This system has two degrees of freedom, which are tuned close to the frequencies corresponding to vertical and torsional symmetric modes of the bridge, that get coupled during flutter. The variable damping of the system is chosen through a fuzzy logic controller using the displacement and velocity at the center of the bridge as the inputs. The transient response of the bridge due to a given initial condition in presence of the wind self-excited forces is controlled so that critical flutter wind speed for the bridge is enhanced. The methodology is applied to increase the flutter wind speed of the Thomas Suspension Bridge. Also, a numerical study is conducted to investigate the effectiveness of the semiactive control scheme.

Artificial Intelligence Based Synthesis of Semiactive Suspension Systems

This paper is concerned with the synthesis of control laws for semiactive suspension systems employing artificial intelligence. A review is made of a simple, 2-degree-of-freedom, quarter car model with passive, active, and semiactive control. An active linear quadratic Gaussian controller and a semiactive, balance logic derived controller are then used to develop two artificial intelligence based controllers-a semiactive neurocontroller and a semiactive fuzzy logic controller. This paper focuses on the advancement of balance semiactive logic using variable dry friction and the development of fuzzy semiactive controllers. The concerns in view are twofold: the reduction in cost of the control system and the antichattering nature of the logic. The development is from an engineering perspective and attempts to reduce the well-known schism between theoreticians and users of feedback control.