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A novel control scheme for the active suspension in a 4-DOFs half-car model is presented. A force cancellation control scheme is used to isolate the sprung and the unsprung masses. Skyhook damper and virtual damper concepts are employed to stabilise the sprung and unsprung masses respectively. Road-following springs are applied for the sprung mass to follow the trend of the road surface condition and to maintain the suspension stroke within a reasonable range. For efficiency, genetic algorithm is employed to search for the parameters like damping ratio and spring constant to achieve an optimum trade off among ride comfort, handling quality, and suspension stroke simultaneously for random input. Computer simulations are performed using MATLAB software to verify the proposed control scheme and effectiveness of the applied genetic algorithm.

This paper analyses the low power factor and harmonic issues in AC to DC converters i.e. conventional diode bridge rectifier and PWM rectifier. The peaky current drawn by the capacitor in diode bridge rectifier is the reason for high total harmonic distortion (THD) and low power factor. This problem can be overcomed by replacing the diode in bridge rectifier with IGBT and pulses given to these switches can be controlled to obtain a unity power factor and low THD. Such rectifier circuit is known as Pulse Width Modulated (PWM) rectifier. The circuits are simulated in MATLAB using simulink and the waveforms are analysed for harmonics, power factor and THD.I.

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This paper presents a half-car model (4-degrees-of-freedom) employing nonlinear passlve sequential damper. The vibration isolation and transmrssibility effect on the vehicle's centre of gravity (C.G.) has been studied. The results have been compared for transmissibility, displacement, and velocity transient response for half-car model having nonlinear passive sequential hydropneumatic damper under different terrain excitation.