Abstract
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.
Highlights
Suspension systems are often used to control response of various rigid and flexible multi-body systems [1,2] and the most commonly used suspension systems in vehicular applications, where they are used to control the tire deflection or wheelhop for handling performance and vehicle body deflection and acceleration for passenger ride comfort [3]
Since first introduced by Crosby and Karnopp [6,7], semiactive suspension systems continue to gain considerable attention in vehicle applications. This is due to its advantageous characteristics over passive system in overcoming the traditional conflict between vehicle safety and handling, and ride comfort, as well as its significantly less complexity and power requirement than active suspension system [8,9,10]
The responses for each control technique and passive system are presented in Fig. 2 for sprung mass acceleration, Fig. 3 for unsprung mass acceleration, Fig. 4 for suspension deflection and Fig. 5 for tire deflection
Summary
Suspension systems are often used to control response of various rigid and flexible multi-body systems [1,2] and the most commonly used suspension systems in vehicular applications, where they are used to control the tire deflection or wheelhop for handling performance and vehicle body deflection and acceleration for passenger ride comfort [3]. The second is the time-domain steady state response analysis, where the Peak-to-Peak values of pure tone input at resonance frequencies are compared. From this single model, all semiactive control scheme as well as passive system can be derived. These different analyses were conducted to compare the passive to the semiactive control techniques (skyhook, groundhook and hybrid), that are transient and steady state responses in time domain and frequency response. In the steady state response analysis, the system is excited with a sinusoidal input with input frequency is set to be equal to the natural frequencies of the system, ω n1 and ωn2 This is to simulate the worst case scenario in which resonances occur. Transmissibility ratios over frequency span for all variables of interest are presented and the control techniques are compared
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