Sany Izan Ihsan

Dynamics and control policies analysis of semi-active suspension systems using a full-car model

Several control policies of semi-active systems, namely skyhook, groundhook and hybrid controls, are presented. Their ride comfort, suspension displacement and road-holding performances are analysed and compared with passive systems. The analysis covers both transient and steady-state responses in the time domain and transmissibility response in the frequency domain. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for typical passenger cars. The hybrid control policy is also shown to be a better compromise between comfort, roadholding and suspension displacement than the skyhook and groundhook control policies.

A comparative ride performance and dynamic analysis of passive and semi-active suspension systems based on different vehicle models

Vehicle models used to evaluate performance and dynamic behaviour are either discrete models, which includes quarter, half, and full car models, or continuous models using finite element modelling. In this work our focus will be on discrete models, which have more popularity with ground vehicle analysts owing to their shorter computational time and lower cost compared with continuous models. In this paper, ride comfort, suspension displacement and road-holding performances are compared for three different models – quarter (Q), half (H) and full (F) car models. In each model, semi-active system controls, namely skyhook, groundhook and hybrid controls, are used along with the conventional passive system. The analysis covers both transient and steady-state responses in the time domain and transmissibility response in the frequency domain. Results show that while the responses give generally the same trend, the simpler model gives significantly higher responses.

Analysis of control policies and dynamic response of a Q-car 2-DOF semi active system

Several control policies of Q-car 2-DOF semiactive system, namely skyhook, groundhook and hybrid controls are presented. Their ride comfort, suspension displacement and road-holding performances are analyzed and compared with passive system. The analysis covers both transient and steady state responses in time domain and transmissibility response in frequency domain. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for typical passenger cars. The hybrid control policy is also shown to be a better compromise between comfort, road-holding and suspension displacement than the skyhook and groundhook control policies.

Analysis of semi-active suspension systems for four-axles off-road vehicle using half-model

Handling and ride quality are affected by many factors, including high-frequency vibrations, body booming, body roll and pitch motion, vertical motion by the suspension system and frequency vibration transmitted from the road input excitations. This article focuses on the most significant vibration source that affects handling and ride quality, which is the suspension system. Passive suspension has been taken as the starting point of this work, in which we discuss the model in context. Semi-active suspension systems are introduced with the aim of exploring the performance of the system compared with passive suspension. Several control policies of semi-active systems, namely, skyhook, ground-hook and hybrid controls, are presented. Their ride comfort, suspension displacement and roadholding performances are analysed and compared with passive systems. The analysis covers both transient and steady-state responses in the time domain and transmissibility response in the frequency domain. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for a typical off-road vehicle. The hybrid control policy is also shown to provide a better compromise between comfort, road-holding and suspension displacement than the skyhook and ground-hook control policies.

Assessment of different semi-active control strategies on the performance of off-road vehicle suspension systems

This paper deals with dynamics and control policies analysis of semi-active suspension systems for off-road vehicles. Three configurations of these vehicles; two-axle, three-axle and four-axle have been studied and their performances are compared. The application of several control policies of semi-active suspension system, namely skyhook; ground-hook and hybrid controls have been analysed and compared with passive systems. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement. The hybrid control policy is also shown to be a better compromise between comfort, road-holding and suspension displacement than the skyhook and ground-hook control policies. Skyhook control generally improves sprung mass responses while at the same time increasing unsprung mass responses. On the other hand, ground-hook control generally improves unsprung mass responses at the expense of the sprung mass responses. Results show an improvement in ride comfort and vehicle handling using four-axle over three-axle and two-axle when emphasis is placed on the response of the vehicle body acceleration, suspension and tyre deflection.

Ride performance analysis of half-car model for semi-active system using RMS as performance criteria

The work aims to study the root mean square (RMS) responses to acceleration input for four state variables: the ms vertical acceleration, the ms pitch angular acceleration and the front and rear deflections of the suspensions. A half-car two degree-of-freedom model of semi-active control scheme is analyzed and compared with the conventional passive suspension system. Frequency response of the transfer function for the heave, pitch of the sprung mass and suspension deflections are initially compared and then mean square analysis is utilized to see the effect of semi-active scheme. Results indicate that significant improvements were achieved in the sprung mass heave and pitch responses using semi-active control scheme. However results for the rear and front suspension deflection show that there are limiting values of damping coefficient beyond which, the semi-active scheme becomes disadvantageous than the passive system.

Analysis and simulation of semi-active suspension control policies for two-axle off-road vehicle using full model

Ride comfort and vehicle handling of heavy off-road vehicles can be improved with the help of a controlled suspension system. This paper describes the impact of a semi-active and passive system on the driving behaviour of a heavy off-road 4 × 4 wheeled vehicle. The analysis is based on a military vehicle model used for simulating off-road vehicle drives and handling. The analysis covers both transient responses and transmissibility response in frequency domain. To start with, the fundamental skyhook, groundhook and hybrid principles are used for controlling. Frequency response and sprung mass accelerations, suspension and tyre deflection response in time domain are clearly improved using semi-active control policies compare to passive system.

Transient and steady state dynamic analysis of passive and semi-active suspension systems using half-car model

Several control policies of semi-active system, namely skyhook, groundhook and hybrid controls are presented using a half-car model, as a continuation of the previous work on quarter-car model. Their ride comfort, suspension displacement and road-holding performances are analysed and compared with passive system. The analysis covers both transient and steady state responses in time domain and transfer function in frequency domain. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for typical passenger cars. The hybrid control policy is also shown to be a better compromise between comfort, road-holding and suspension displacement than the skyhook and groundhook control policies.

Optimisation and control of semi-active suspension using genetic algorithm for off-road full vehicle

The main role of a suspension system of a vehicle is to prevent the road excitations from being transmitted to the passengers. In this study, we develop and obtain a strategy to optimise the main design parameters of a semi-active suspension for a two-axle full off-road vehicle. The objective is to minimise the maximum bouncing acceleration of the sprung mass. Owing to the importance of ride comfort for off-road vehicles, minimising the settling time and peak-to-peak of the vertical, pitch and roll acceleration would lead to better ride comfort. In solving this problem, the genetic algorithms have consistently found near-optimal solutions within specified parameters ranges for several independent runs.

A study on automated traction control system of an electrical golf car

This study presents an automated traction control system (ATCS) without incorporating the function of hydraulic system. The ATCS is used for improving the vehicle performance in terms of stability and torque or speed needed in order to produce smooth driving. Driving motor and wheel speed sensor (WSS) with RPM meter are used in this study to develop the sufficient torque or speed on demand of the driving wheel. The current flow is controlled to the driving motor with the help of electronic proportional valve. A slope sensor is used in the proposed system to enhance the power supply to the driving motor when the vehicle will be in the grade of 10%-20%. SolidWorks simulation and laboratory experiment has been performed to investigate the performance of the designed and developed automated traction control system on the dry and slippery surface.