Compliant dynamics of a rectilinear rear-independent system

Author(s):  
Xiang Liu ◽  
Jing-Shan Zhao ◽  
Zhi-Jing Feng

The rectilinear rear-independent suspension investigated in this paper could remain the wheel alignment parameters invariable in theory. However, its dynamics is much more complex than that of the existing suspensions because of its redundant constraints in structure. Considering the elasticity of the rectilinear rear-independent suspension, a rigid-flexible half-car dynamic model is established for the first time based on the discrete time transfer matrix method. At the same time, a rigid half-car dynamic model is established as a comparison. The natural frequency characteristics and dynamic response of the rectilinear rear-independent suspension under random road excitations are analyzed and compared with those of rigid half-car dynamic model. The results reveal that the suspension system has apparent influence to the dynamics of vehicle. The wheel alignment parameters will fluctuate within a narrow range which is mainly determined by the rolling vibration of vehicle. And the suspension system could reduce and filter the road excitations with high frequency and small amplitude. This provides a good effect on the ride comfort of vehicle. Dynamics analysis of the rectilinear rear independent suspension reveals that the proposed modeling approach could deal with the dynamics of rigid-flexible multibody systems with redundant constraints effectively.

Two wheelers like motorbikes and scooters are one of the major transports in India. In major cities and towns, it is most common private transport as it is fast and easy approach to the destination. But the prolonged drive in the two-wheeler leads to the potential health hazard and musco-skeletal disorder due to continuous exposure to the vibration caused during the ride and force transmitted to the vehicle body due to road irregularities. It is a challenge of automobile engineers to design a promising suspension system to overcome the risk of ride comfort during continuous driving. In this research, two-wheeler suspension system is modelled with a condition of bump and valley in a wavy road. The road surface is assumed to be wavy and the response of new suspension spring with different materials (stainless steel, tungsten and polymeric) along with viscous damper is analyzed and compared. By this analysis, it will be proposed to industry to modify the suspension system to improve its efficiency and reduce force transmitted to the human body to improve the ride comfort


2020 ◽  
Vol 10 (12) ◽  
pp. 4320 ◽  
Author(s):  
Dou Guowei ◽  
Yu Wenhao ◽  
Li Zhongxing ◽  
Amir Khajepour ◽  
Tan Senqi

This paper presents a control method based the lateral interconnected air suspension system, in order to improve the road handling of vehicles. A seven-DOF (Degree of freedom) full-vehicle model has been developed, which considers the features of the interconnected air suspension system, for example, the modeling of the interconnected pipelines and valves by considering the throttling and hysteresis effects. On the basis of the well-developed model, a sliding mode controller has been designed, with a focus on constraining and minimizing the roll motion of the sprung mass caused by the road excitations or lateral acceleration of the vehicle. Moreover, reasonable road excitations have been generated for the simulation based on the coherence of right and left parts of the road. Afterwards, different simulations have been done by applying both bumpy and random road excitations with different levels of roughness and varying vehicle lateral accelerations. The simulation results indicate that the interconnected air suspension without control can improve the ride comfort, but worsen the road handling performance in many cases. However, by applying the proposed sliding mode controller, the road handling of the sprung mass can be improved by 20% to 85% compared with the interconnected or non-interconnected mode at a little cost of comfort.


2002 ◽  
Vol 8 (7) ◽  
pp. 967-991 ◽  
Author(s):  
Javad Marzbanrad ◽  
Goodarz Ahmadi ◽  
Yousef Hojjat ◽  
Hassan Zohoor

An optimal preview control of a vehicle suspension system traveling on a rough road is studied. A three-dimensional seven degree-of-freedom car-riding model and several descriptions of the road surface roughness heights, including haversine (hole/bump) and stochastic filtered white noise models, are used in the analysis. It is assumed that contact-less sensors affixed to the vehicle front bumper measure the road surface height at some distances in the front of the car. The suspension systems are optimized with respect to ride comfort and road holding preferences including accelerations of the sprung mass, tire deflection, suspension rattle space and control force. The performance and power demand of active, active and delay, active and preview systems are evaluated and are compared with those for the passive system. The results show that the optimal preview control improves all aspects of the vehicle suspension performance while requiring less power. Effects of variation of preview time and variations in the road condition are also examined.


2014 ◽  
Vol 592-594 ◽  
pp. 2165-2178 ◽  
Author(s):  
M.W. Trikande ◽  
Vinit V. Jagirdar ◽  
Muraleedharan Sujithkumar

Comparative performance of vehicle suspension system using passive, and semi-active control (on-off and continuous) has been carried out for a multi-axle vehicle under the source of road disturbance. Modelling and prediction for stochastic inputs from random road surface profiles has been carried out. The road surface is considered as a stationary stochastic process in time domain assuming constant vehicle speed. The road surface elevations as a function of time have been generated using IFFT. Semi active suspension gives better ride comfort with consumption of fraction of power required for active suspension. A mathematical model has been developed and control algorithm has been verified with the purpose/objective of reducing the unwanted sprung mass motions such as heave, pitch and roll. However, the cost and complexity of the system increases with implementation of semi-active control, especially in military domain. In addition to fully passive and fully semi-active a comparison has been made with partial semi-active control for a multi-axle vehicle to obviate the constraints. The time domain response of the suspension system using various control logics are obtained and compared. Simulations for different class of roads as defined in ISO: 8608 have been run and the ride comfort is evaluated and compared in terms of rms acceleration at CG in vertical direction (Z), which is the major contributor for ORV (Overall Ride Value) Measurement.


2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Chi Nguyen Van

The states of the suspension system including the road excitation depend on the road quality, the velocity of the car, and the sprung mass. Those states play a very important role in the control problem of stability, ride comfort, ride safety, and dynamic wheel load of the suspension systems. The velocities and deflections of the sprung mass and unsprung mass would not be measured fully in the practice. Therefore, it must be estimated by other measured quantities from the system such as acceleration and deflection of sprung mass and unsprung mass. To control the active suspension system, its states need to be estimated accurately and guaranteed the response time. This paper presents the method using the sigma point Kalman filter to estimate the suspension system’s states including the road excitation, the deflections, and the velocities of the sprung mass and unsprung mass. The mathematical model of the suspension system is rewritten for the state estimation problem, and the stochastic load profile is supposed the main noise input. The stochastic characteristic of the road excitation depending on the car’s velocity is taken into account in the model used for suspension system state estimation. The results calculated based on the practical experiment data for specific road profile with some particular velocities of the car show that the suspension system states are estimated quite accurately in comparison with the practice states.


Author(s):  
G. Galmarini ◽  
M. Gobbi ◽  
G. Mastinu

The need to decrease pollution in urban zones has pushed toward severe regulations in term of low-emission limits. The effect of this “environmental awareness” is an increased interest in electric vehicles (EV). The construction of a EV is presented in the paper. This vehicle has been designed specifically to be powered by electric motors, the suspension system and the general layout have been developed accordingly. According to the European technical regulations, the vehicle has been designed for a city use. The main features of GreenFun, (this is the name of the prototype), are an extensive use of composite and lightweight materials, a special suspension system layout, a 4WD powertrain realized by means of 4 electric motor hubs and the use, for the first time in a production vehicle, of 4 measuring wheels that are able to measure the forces acting between the pneumatic tires and the road. These information are used as input for the vehicle control systems in order to enhance performance and safety. In the paper, the most relevant vehicle subsystems are described in detail (chassis, wheel, suspensions, powertrain, energy management, control system, …).


Author(s):  
Abbas Soltani ◽  
Ahmad Bagheri ◽  
Shahram Azadi

This article presents an integrated control of yaw, roll and vertical dynamics based on a semi-active suspension and an electronic stability control with active differential braking system. During extreme manoeuvres, the probability of vehicle rollover is increased and the stability of lateral and yaw vehicle motions is deteriorated because of the saturation of tyre forces. Furthermore, when the road excitation frequencies are equal to the natural frequencies of the unsprung masses, the resonance phenomena occurs, which causes some oscillations getting revealed on responses of the yaw and lateral vehicle dynamics. In these situations, the active braking alone cannot be helpful to improve the vehicle handling and stability, considerably. In order to overcome these difficulties, a coordinated control of the semi-active suspension and the active braking is proposed, using a fuzzy controller and an adaptive sliding mode controller, respectively. A non-linear full vehicle model with 14 degrees of freedom is established and combined with the modified Pacejka tyre model. As the majority of vehicle dynamics variables and the road profile inputs cannot be measured in a cost-efficient way, a non-linear estimator based on unscented Kalman filter is designed to estimate the entire vehicle dynamics states and the road unevenness. Simulation results of the steering manoeuvres on the random road inputs show that the proposed chassis system can effectively improve the vehicle handling, stability and ride comfort.


Author(s):  
Hao Chen ◽  
Mingde Gong ◽  
Dingxuan Zhao ◽  
Jianxu Zhu

This paper proposes an attitude control strategy based on road level for heavy rescue vehicles. The strategy aims to address the problem of poor ride comfort and stability of heavy rescue vehicles in complex road conditions. Firstly, with the pressure of the suspension hydraulic cylinder chamber without a piston rod as the parameter, Takagi–Sugeno fuzzy controller classification and adaptive network-based fuzzy inference system controller classification are used to recognise the road level. Secondly, particle swarm optimisation is adopted to obtain the optimal parameters of the active suspension system of vehicle body attitude control under different road levels. Lastly, the parameters of the active suspension system are selected in accordance with the road level recognised in the driving process to improve the adaptive adjustment capability of the active suspension system at different road levels. Test results show that the root mean square values of vertical acceleration, pitch angle and roll angle of the vehicle body are reduced by 59.9%, 76.2% and 68.4%, respectively. This reduction improves the ride comfort and stability of heavy rescue vehicles in complex road conditions.


2011 ◽  
Vol 105-107 ◽  
pp. 500-503
Author(s):  
Wen Rui Wang ◽  
Han Chen ◽  
Sai Du ◽  
Bo Yang

A comprehensive nonlinear vehicle model of a tracked vehicle suspension is established by using multi-body dynamics software Recurdyn, which is used to be simulated ride comfort dynamic response. In the paper, the multi-body model dynamics vibration characters of vehicle suspension is simulated, which is accomplished by testing the model on the different roads (such as level-D,E&F Road) by different vehicle riding speed. The influence factors about ride comfort are found by the stimulation, which are the road level,the velocity of the vehicle and other parameters of the suspension system. The experiment about the vehicle ride comfort performance proves that using the multi-body model simulation in the paper could be helpful to select appropriate suspension system parameters in the structure and performance design about tracked vehicle suspension, which could give theory bases about suspension active controlling strategy of the suspension.


2013 ◽  
Vol 765-767 ◽  
pp. 382-386
Author(s):  
Jian Kun Peng ◽  
Hong Wen He ◽  
Bing Lu

A 7-DOFs vehicle dynamics model which includes active suspension system (ASS) is established, and a LQR controller for active suspension system was designed based on optimal control theory. The simulation models for active suspension system and passive suspension system were built, and a simulation experiment was carried out with MATLAB/Simulink Software. The simulation results show that the optimal control of active suspension system can reduce vertical, roll and pitch accelerations of sprung mass, and the vehicle ride comfort and handling stability were improved effectively.


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