Saad Kashem

Comparison between different sets of suspension parameters and introduction of new modified skyhook control strategy incorporating varying road condition

This study examines the uncertainties in modelling a quarter car suspension system caused by the effect of different sets of suspension parameters of a corresponding mathematical model. To overcome this problem, 11 sets of identified parameters of a suspension system have been compared, taken from the most recent published work. From this investigation, a set of parameters were chosen which showed a better performance than others in respect of peak amplitude and settling time. These chosen parameters were then used to investigate the performance of a new modified continuous skyhook control strategy with adaptive gain that dictates the vehicles semi-active suspension system. The proposed system first captures the road profile input over a certain period. Then it calculates the best possible value of the skyhook gain (SG) for the subsequent process. Meanwhile the system is controlled according to the new modified skyhook control law using an initial or previous value of the SG. In this study, the proposed suspension system is compared with passive and other recently reported skyhook controlled semi-active suspension systems. Its performances have been evaluated in terms of ride comfort and road handling performance. The model has been validated in accordance with the international standards of admissible acceleration levels ISO2631 and human vibration perception.

Vehicle Suspension System

The quarter-car suspension model is the best benchmark to study and analyse the dynamic behaviour of vehicle vertical isolation properties. This chapter presents background information and a description of the quarter-car suspension model which includes passive, semi-active and active suspension. This chapter also consists of a comparison of various models to determine the appropriate quarter-car model to compare the control systems discussed in Chap. 4.

Design of Semi-active Suspension System

One of the key issues in the design of an active or semi-active suspension system is to identify the appropriate control algorithm. This chapter describes the proposed modified skyhook control closed-loop feedback system and its effectiveness in a semi-active suspension system. The chapter comprises four main sections. The first section describes the proposed and three existing skyhook control algorithms, while the second section describes the road profile that needs to be generated to evaluate the controller performances. The third section presents the simulation of the quarter-car model as described in Chap. 3 with the semi-active control algorithms. The last section is comprised of simulation and experimental analysis of the Quanser quarter-car suspension plant designed and manufactured by Quanser Inc. The last two sections also compare the results of different control techniques and evaluate the proposed modified skyhook control algorithm. The comparison has been done in terms of ride comfort and road-handling performance. On the other hand, the evaluation consists of a human vibration perception test and admissible acceleration levels test based on ISO 2631.

Simulation of Full Car Model

In this chapter, the analysis of the simulation results of the dynamic model of a full car model which considers the road bank angle is presented. The first section describes the parameters of the full car that have been used in the analysis model and the environment of the simulation. The second section describes the performance of the proposed skyhook control system under different road conditions. The performance of the combined approach, the proposed skyhook controller, is activated along with the direct tilt control which was evaluated in different driving scenarios in the third section. The next section is comprised of the summary of the simulation while the vehicle is travelling on road class C and following driving scenario four.

Experimental Analysis of Full Car Model

In this chapter, the analysis of the dynamics of a full car model is presented. It incorporates the response of the Quanser quarter-car suspension plant as one of the four wheels of the full car model. Section 7.1 describes the environment of the experimental analysis and the parameters of the full car that emulated from the Quanser quarter-car suspension plant. The vehicle performance analysis using the Quanser quarter-car suspension plant at the front left and rear right wheel of the full car model is presented separately in Sects. 7.2 and 7.3. The performance of the combined approach where the proposed skyhook controller is activated along with the direct tilt control is evaluated in Sects. 7.2 and 7.3 at frequency domain and time domain.

Full Car Model Cornering Performance

In this chapter, a dynamic model of a full car which considers the road bank angle is developed. The first section describes the full car model design along with the vehicle tilting model. The vehicle rollover estimation procedure is described in Sect. 5.1. Section 5.2 describes the controller design that is required to control the vehicle tilt while cornering. The next section is comprised of descriptions of the road profiles and driving scenarios that will be used in simulation and experimental analysis in the next two chapters. The evaluation criteria are described in the last section to compare the results of different controllers in terms of ride comfort, admissible acceleration level test based on ISO 2631 and road handling performance.

Control Strategies in the Design of Automotive Suspension Systems

In the literature available, many robust and optimal control approaches or algorithms were found in the design of automotive suspension systems. In this chapter, some of these will be reviewed such as the linear time-invariant H-infinity control (LTIH), the linear parameter-varying control (LPV) and model-predictive controls (MPC). Five widely known control approaches, namely, the linear quadratic regulator (LQR) and linear quadratic Gaussian (LQG), sliding mode control (SMC), fuzzy and neuro-fuzzy control, skyhook and groundhook approaches, are reviewed more deeply. Since the damper plays an important role in the semi-active suspension system design, different types of damper technologies are discussed in the second section. This includes the Quanser electromagnetic damper that was used in the experimental analysis in this manuscript. Another major objective of this manuscript is to tilt the standard passenger vehicle inward during cornering. So a brief literature review on automotive tilting technology is included in the last section.