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Vehicle models for road profile identification by drive-by bridge inspection method
Published in Airong Chen, Xin Ruan, Dan M. Frangopol, Life-Cycle Civil Engineering: Innovation, Theory and Practice, 2021
N. Toshi, S. Hasegawa, K.C. Chang, C.W. Kim
The above results implied that the lower-frequency components of road profile were better identified using the vehicle models without unsprung masses, and the higher-frequency components were better identified using the vehicle models with unsprung masses. These observations are mechanically reasonable in regards of vehicle’s natural frequencies. Known that generally sprung masses (modelling vehicle bodies) are heavier than unsprung masses (modelling tires) and that sprung masses are supported by softer springs than unsprung masses are, the sprung mass is majorly dominated by lower frequency vibrations and the unsprung mass by higher frequency vibrations. Take the 2DOF quarter-car model for example, the sprung mass is dominated by natural frequency of 1.18 Hz and the unsprung mass by 10.2 Hz. The model without unsprung mass may lose sensitivity to higher frequency inputs and therefore lose accuracy in recovering the higher frequency components. Contrarily, the model with unsprung mass may perform better in recovering higher frequency components.
Semi-Active Suspension Systems
Published in Osita D. I. Nwokah, Yildirim Hurmuzlu, The Mechanical Systems Design Handbook, 2017
An optimal SA control problem is, therefore, formulated (for the SQC model of Figure 12.14) to briefly highlight the design procedure. For the performance index (PI) in the design of vehicle suspension, sprung mass acceleration, suspension travel, and tire spring excursion can be incorporated. Sprung mass acceleration is a measure of body isolation, i.e., passenger ride comfort. Suspension travel or rattle space is typically a design constraint for limiting rigid body motion of the vehicle. Tire spring stroke (or equivalently, dynamic tire force) is an indicator of road-holding ability. Accordingly, a PI of the following form can be selected: PI=12TE∫0T{γ1z¨22+γ2(z1−z0)2+γ3(z2−z1)2}dt
Vehicle Data Sources for the Accident Reconstructionist
Published in Donald E. Struble, John D. Struble, Automotive Accident Reconstruction, 2020
Donald E. Struble, John D. Struble
Sprung Mass and Unsprung Masses: The sprung mass is a rigid body having the same inertial properties (mass and mass moments of inertia about the same axes) as the total sprung weight. The unsprung masses move with, and are supported by, the tires (which of course have vertical compliance of their own).
Lightweight design of the in-wheel motor considering the coupled electromagnetic-thermal effect
Published in Mechanics Based Design of Structures and Machines, 2022
Di Tan, Yanshou Wu, Jie Feng, Kun Yang, Xijie Jia, Chao Ma
For the in-wheel motor (IWM) driving electric vehicle, the IWM, speed reducer and brakes are all integrated in wheels, which make the un-sprung mass increase. Many scholars show that the increase of the un-sprung mass of the vehicle causes increased tire dynamic load and body vibration acceleration, and has adverse effect on the riding quality and comfort of vehicles (Purdy and Simner 2004; Luo and Tan 2012). Therefore, the lightweight problem of IWM driving system has become one of the critical issues for the development of IWM driving electric vehicles.
Experimental Validation of LQR Weight Optimization Using Bat Algorithm Applied to Vibration Control of Vehicle Suspension System
Published in IETE Journal of Research, 2022
T. Yuvapriya, P. Lakshmi, Vinodh Kumar Elumalai
Figure 1 illustrates the schematic diagram of a quarter-car model with ASS. The ASS represents a double-mass-spring damper system and receives the control input from the electrical actuator to control the vehicle body acceleration due to the road surface irregularities. The sprung mass represents the vehicle chassis supported by a spring and a damper . The unsprung mass indicates the mass of the wheel equipped with a spring and a damper and , respectively [7,20,26]. The electrical actuator, which acts as a bridge between the wheel and the vehicle body, creates the control force to neutralize the forces created by the uneven road surface. Since the control force is applied in the opposite direction of the force created by the uneven road surface, the vibrations reflected to the vehicle body is very much suppressed, thereby increasing the ride comfort. The equations of motion, which represents the dynamics of the ASS, are as follows. To derive the state space model of the ASS, the following states are considered for state vector: , with , , and indicating the suspension deflection, the velocity of vehicle body, the tire deflection, and the velocity of tire. The control force is the state input and the vehicle chassis acceleration and the suspension deflection are the outputs. Hence, the state space model of ASS system can be obtained as follows. Table 1 gives the parameters of the quarter-car ASS. The challenging control objective of ASS is that the vertical accelerations of the vehicle body should be minimized while ensuring the suspension deflection within the permissible level. Particularly, to avoid any structural damage to the wheel assembly, the suspension deflection should be restricted before reaching the maximum level [28]. Moreover, to assure passenger safety, the dynamic load of the tire must be less than its static load as given below. Since these conflicting control objectives can be synthesized as an optimization problem, in this work, an optimal state feedback control technique is synthesized to guarantee passenger comfort and road handling features of ASS. In the next section, we explain the problem formulation based on the linear quadratic framework and present the optimal weight selection of LQR applied for ASS.