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-ac
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Design of Semi-active Suspension System
Abstract 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.
4.1
Semi-active Control Algorithms
On the basis of the two degrees of freedom semi-active suspension system described in Chap. 3, passive and four semi-active suspension systems have been modelled. The continuous skyhook control of Karnopp et al. [14], modified skyhook control of Bessinger et al. [15], optimal skyhook control of Nguyen et al. [51] and the proposed modified skyhook control strategies are used in designing the semi-active suspension system. The control strategies are described below.
4.1.1
Continuous Skyhook Control of Karnopp et al. [14]
The semi-active continuous skyhook control strategy of Karnopp et al. [14] can be represented by the following equation:
© Springer Nature Singapore Pte Ltd. 2018 S. Kashem et al., Vehicle Suspension Systems and Electromagnetic Dampers, Springer Tracts in Mechanical Engineering, DOI 10.1007/978-981-10-5478-5_4
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4 Design of Semi-active Suspension System
2 333 2 82 > • > > > 6max6C :min6Csky z2 C 777 z• z• for z• z• z• 0 < 5 4 5 4 min 5 4 • max 2 1 2 2 1 • ð4:1Þ fd ¼ z2 z1 > > • > • • • • > : Cmin z2 z1 for z2 z2 z1 < 0 where fd is the semi-active damping force of the actuator. This strategy is used in many recent studies [139, 140]. According to this control strategy, the effective damping of the skyhook damper is bounded by a high and a low level. Determining whether the damper is to be adjusted to either its low state or its high state depends on the product of the velocity of the spring mass attached to • • • that damper z2 and the relative velocity across the suspension damper z2 z1 . If this product is greater than or equal to zero, then the high state of the damper is applied. If this product is negative, the damper is adjusted to its low state. In this situation, it is bette
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