Automotive Suspension Research Articles

Bypass Rotary Magnetorheological Damper for Automotive Applications

A novel concept of bypass rotary Magneto-rheological (MR) damper is studied in the automotive suspension application. The proposed design is developed based on a vane-type damper structure with an MR control valve located outside of the damper. The design is intended to enhance the ease of maintenance and to reduce the thermal effect from the coil to the MR fluid. The valve is the key component of the damper that exploits the advance characteristics of MR fluid in which have sensitive rheological properties to magnetic field. The ability of the valve to modify the strength of magnetic field has given an advantage that the valve can be operated without any moving parts. The elimination of these parts in the throttling mechanism of the valve will provide benefit in terms of product lifetime and responsiveness. The main objective of this paper is to elaborate the advantages of the bypass rotary MR damper and to demonstrate the damper performance through force-velocity characteristics. The analytical model of the damper is developed and used in the determination of the force-velocity curves and the equivalent damping coefficients.

Mixed H2/H∞ with Pole-Placement Control Design Outline for Active Suspension Systems

This paper consider the control of active automotive suspensions applying Mixed (H2/H∞) state-space optimization techniques. It is well known that the ride comfort is improved by reducing vehicle body acceleration generated by road disturbance. In order to study this phenomenon, Two Degrees of Freedom (DOF) in state space vehicle model was built in. However, the H∞ control method attenuates the agitation effect on the output while H2 is employed to improve the input of the controller. Linear Matrix Inequality (LMI) technique is employed to calculate the dynamic controller parameters. The outcome of the simulation revealed that ride comfort for the vehicle upgraded adequately by applying mixed H2/H∞ Control method for active suspension system, and also the mixed H2/H∞ Control method was more effective than the H∞ Control method.

The tangent stiffness matrix in rigid multibody vehicle dynamics

In the development of the equations of motion of a rigid multibody system, particularly vehicles, it is quite common to linearize the equations after they are derived, or even to ignore the non-linear terms from the outset. When doing so, the tangent stiffness matrix, i.e., the stiffness term that results from preload of the system rather than physical flexibility, is often ignored. The motion analysis of preloaded mechanical systems, e.g., the ride quality analysis of vehicle suspensions, may be significantly altered by this omission. Explicit expressions for the tangent stiffness matrix for a few of the common constraint types, including the revolute joint and the rolling wheel, are derived in this article. These expressions are coded into software and included in an open-source linear equation of motion generator for rigid multibody systems. A sample automotive suspension system is analysed, comparing the results with and without the tangent stiffness matrix effects; additionally, a benchmark solution is developed using a commercial multibody dynamics code. The results provide confirmation of the significance of the tangent stiffness effect on motion analysis and correlate well with non-linear transient solutions.

Investigation of Vehicle Parameters in Regenerative Coil Suspension Design

Regenerative type suspensions are employed to recover energy that is unproductively dissipated in dampers in automotive suspension system. In order to effectively recover energy from suspension, an attempt has been made in the design to capitalize the vehicle parameters and concoct a suitable linear generator in unison with helical spring. The performance characteristics drawing suitable inferences between the vehicle parameters and suspension specifications are well investigated.

Co-Design of an Active Suspension Using Simultaneous Dynamic Optimization

Design of physical systems and associated control systems are coupled tasks; design methods that manage this interaction explicitly can produce system-optimal designs, whereas conventional sequential processes may not. Here, we explore a new technique for combined physical and control system design (co-design) based on a simultaneous dynamic optimization approach known as direct transcription, which transforms infinite-dimensional control design problems into finite-dimensional nonlinear programming problems. While direct transcription problem dimension is often large, sparse problem structures and fine-grained parallelism (among other advantageous properties) can be exploited to yield computationally efficient implementations. Extension of direct transcription to co-design gives rise to new problem structures and new challenges. Here, we illustrate direct transcription for co-design using a new automotive active suspension design example developed specifically for testing co-design methods. This example builds on prior active suspension problems by incorporating a more realistic physical design component that includes independent design variables and a broad set of physical design constraints, while maintaining linearity of the associated differential equations. A simultaneous co-design approach was implemented using direct transcription, and numerical results were compared with conventional sequential optimization. The simultaneous optimization approach achieves better performance than sequential design across a range of design studies. The dynamics of the active system were analyzed with varied level of control authority to investigate how dynamic systems should be designed differently when active control is introduced.

Efficient Modeling of MR Dampers

The Magneto-Rheological (MR) dampers are devices that use a MR fluid that can quickly change their rheological properties if a magnetic field is applied. Being part of an automotive suspension (semi-active ) can dissipate energy in a controlled manner, which has important benefits as comfort, road holding, safety, etc. The modeling of MR dampers allows the design of better automatic control. Based on the modification of existing models for passive dampers; new modified models, with descriptive features, computationally efficient and easy identification procedures are proposed. The models reproduce the characteristic diagrams of the MR dampers that are needed for the system design of automatic control of semi-active suspension. An analysis justifies the incorporation of electric current and acceleration as model variables. The results are experimentally validated in an industrial laboratory and improving the current results showing good accuracy (errors less than the 5-10 %).

A New Adaptive Controller for Performance Improvement of Automotive Suspension Systems with MR Dampers

© SAE,Khajepour, A. and Agrawal, A., A New Adaptive Controller for Performance Improvement of Automotive Suspension Systems with MR Dampers, SAE Int. J. Passeng. Cars - Mech. Syst. 7(3):959-971, 2014, doi:10.4271/2014-01-0052.

Design, Fabrication, and Analysis of a Hybrid FIBER Composite Monoleaf Spring Using Carbon and E-Glass Fibers for Automotive Suspension Applications

The leaf spring is an important component that provides suspension and plays a vital role in automotive applications. As a vehicle travels, a tremendous force, mostly in terms of a fatigue load, is applied to the leaf spring assembly, particularly to the eye point of the rear axle. In a vehicle with rear-wheel drive, the leaf spring is subject to twisting forces that are opposite in direction and magnitude during the acceleration of drive wheels. A multileaf spring provides an additional strength, but lacks the flexibility and increases the overall weight of the vehicle. Considering the loading conditions, the availability of space in a vehicle, and geometrical considerations, a composite monoleaf spring is designed. In due consideration of the tensile behavior, fatigue resistance, chipping resistance, and base part resistance, a hybrid laminated spring is constructed for the purpose. The present study focuses on an analysis and behavior of a monoleaf spring made of hybrid composite materials, i.e., carbon and E-glass fibers. It is observed that the natural frequency of a hybrid composite leaf spring is twice the frequency of a conventional leaf spring, particularly in the vertical direction, which means that the occurrences of resonance will be less. Also, it is observed that the stress produced in it is lower than that in a conventional leaf spring. The hybrid composite monoleaf spring proved to have better impact and tensile behavior than a steel one.

Implementation of LQR Controller on Electromagnetic Suspension System for Passenger’s Car

In the past few decades, researchers have been focusing on improving control strategy for automotive active suspension system. There are few configurations used in active suspension mechanism and one of them is Electromagnetic Suspension (EMS) System. In this study, the implementation of a Linear Quadratic Regulator (LQR) controller in an EMS System for vehicle Active Suspension System (ASS) was investigated. This provides an optimal control solution for the active suspension system. Quarter vehicle model of an electromagnetic suspension was derived and employed to study the implementation of the LQR controller. Detailed parametric analysis for the proposed controller and implementation results will be presented in this paper. This is done by investigating the effect of weighting parameters in the performance index of the optimal control strategy in stabilising the vehicle response. The controller’s performance was compared against a passive suspension system based on a commercial passenger’s car. Parametric analyses revealed the importance of weighting parameters in the optimal control formulation. Finally, it was proven that LQR controller strategy provides a satisfactory improvement for the EMS system compared to passive suspension performance

Adaptive Super-Twisting Observer for Estimation of Random Road Excitation Profile in Automotive Suspension Systems

The estimation of road excitation profile is important for evaluation of vehicle stability and vehicle suspension performance for autonomous vehicle control systems. In this work, the nonlinear dynamics of the active automotive system that is excited by the unknown road excitation profile are considered for modeling. To address the issue of estimation of road profile, we develop an adaptive supertwisting observer for state and unknown road profile estimation. Under Lipschitz conditions for the nonlinear functions, the convergence of the estimation error is proven. Simulation results with Ford Fiesta MK2 demonstrate the effectiveness of the proposed observer for state and unknown input estimation for nonlinear active suspension system.

Analysis of On/Off Controllers of a Semi-Active Suspension in a CAN

Abstract A performance analysis of automotive semi-active suspension control algorithms was realized. Three on/off control strategies were tested in a quarter of vehicle model: hybrid Sky Hook-Ground Hook , hybrid Mix-1-Sensor and Frequency Estimation-Based controller. A commercial Magneto-Rheological damper was modeled by using an Artificial Neural Network approach. The automotive semi-active suspension was implemented in a commercial Controller Area Network system; and the control algorithms were implemented in a micro-controller system with comfort and road holding as main goals. Early results show the feasibility of this application.

Holistic life cycle approach for lightweight automotive components

Since sustainability and environmental issues rose lately, lightweighting has been the point of interest for automotive and aerospace sectors. Lightweighting reduces the fuel consumption of the vehicles and as a result of this reduces emissions. Aluminum, especially wrought aluminum alloys, have large potentials for dramatic weight reduction of structural parts while maintaining the safety and performance. Wrought aluminum alloys are used in automotive skin, bumpers and suspension parts etc. Lightweight suspension parts improve the ride quality and handling, additional to fuel consumption and emission reduction. Holistic life cycle approach takes into account the material flows and related information flows in order to achieve these material flows through the life cycle of the components as well as performance characteristics not only in technical and economic terms but also environmental and social terms. It is necessary to have seamless information flow through the life cycle of the components that could be enabled by the closed-loop product life cycle management (PLM). Closed-loop PLM may also help collection of life cycle information which is necessary to generate performance characteristics and distribution of performance characteristics among life cycle actors.

Comparison of Heuristic Controllers for an Automotive Semi-Active Suspension

A comparative analysis between two different heuristic suspension control strategies is presented, the approaches have been designed to control the vertical dynamics of a full size pick-up truck model equipped with Magneto-Rheological (MR) dampers. The control schemes to compare are: (1) a global suspension controller and, (2) four independent controllers, one for each Quarter of Vehicle (QoV) model; both control schemes depend only on measurements. The main idea is to compare the control performances and the implications that these heuristic controllers have. Experimental data are used to model an MR damper in each corner. Two tests have been used to compare the control performances when the vehicle is driven in straight trajectories: (1) a running test on a road based on the standard ISO 8606 and, (2) a road that excites the vertical dynamics at different frequencies (Bounce Sine Sweep test). Results obtained using CarSimTM show that the comfort performance is better when the controller is well coordinated among the wheel-stations (global suspension controller); the improvement is 33% in the heave motion and 35% in the pitch angle. The QoV -based controller presents uncoordination that complicates the attenuation of the vehicle body movement; however, the road holding is improved.

Development of a new air spring dynamic model

The design of automotive suspension systems involves compromise between the ride quality and driving stability. The change of the damping and stiffness coefficients could provide adaptive characteristic of the suspension system. Air springs, as suspension elements, could provide change of the stiffness coefficient by simply including or excluding additional volumes and thus could provide a controlled variable spring rate. Study of the influence of air springs on the vehicle vertical dynamics, requires use of dynamic air spring models. This paper deals with air spring models. Dynamic model of an air spring with frequency dependent characteristics is presented. The flow resistance in air springs is present when two volumes are connected and it depends on the design characteristics of the connecting pipeline. In order to have the dynamic model without many experimentally obtained parameters, the methodology for defining flow resistance coefficients is developed and presented in this paper. The verification of the dynamic air spring model is done by an experiment. The simulation and experimental results are analysed.

Hardware-in-the-Loop Simulation for Active Force Control with Iterative Learning Applied to an Active Vehicle Suspension System

The paper focuses on the practical implementation of a novel control method to an automotive suspension system using active force control (AFC) with iterative learning algorithm (ILA) and proportional-integral-derivative (PID) control strategy. The overall control system to be known as AFC-IL scheme essentially comprises three feedback control loops to cater for a number of specific tasks, namely, the innermost loop for the force tracking of the pneumatic actuator using PI controller, intermediate loops applying AFC with ILA strategy for the compensation of the disturbances and the outermost loop using PID controller for the computation of the desired force. A number of experiments were carried out on a physical test rig with hardware-in-the-loop simulation (HILS) feature that fully incorporates the theoretical elements. The performance of the proposed control method was evaluated and benchmarked to examine the effectiveness of the system in suppressing the vibration effect of the suspension system. It was found that the experimental results demonstrate the superiority of the active suspension system with proposed AFC-IL scheme compared to the PID and passive counterparts.

Effect of Nitriding Cold Roled and Shot Peening on Automotive Component Fatigue Life

The finite element modeling and analysis have been performed to investigate the effects of nitriding, cold rolled and shot peening on fatigue life of an automotive lower suspension arm component which fabricated of SAE1045 steel. The finite element analysis (FEA) results indicate a great effect for all surface finish parameters on fatigue life. It shows that nitriding increased the fatigue life of the component better than shot peening, while cold rolled effect was between them. In a nut shell, nitriding can be considered as the best surface treatment to improve the fatigue life of the automotive lower suspension arm which fabricated of SAE1045 steel.

Comparison of Characteristics of the Components Used in Mechanical and Non-Conventional Automotive Suspensions

The paper presents the comparison of the characteristics of spring and damping components used in conventional and non-conventional automotive suspensions. The conventional suspension is based on steel coil springs and hydraulic dampers with fixed characteristics. As an example, the adaptive non-conventional suspension shows the characteristics of hydropneumatic suspension components (suspension are constantly being developed and is now based on mechatronic control systems of damping characteristics). The paper summarizes the advantages and disadvantages of these solutions.

Based on Single Neuron PID Control of Vehicle Active Suspension System

Relative to the passive suspension, automotive active suspension car driving more ride comfort and stability, has a vital role to further improve the performance of the vehicle. For such a typically complex active suspension system research, the key issue is the selection of control strategies. The problems in the currently active suspension control strategy, the principle of a simple, effective, this paper, a single neuron PID control strategy used in the automotive active suspension system. The results show that compared with other control strategies, single neuron PID control strategy is reliable, has more advantages.

Analysis of multi leaf spring based on contact mechanics - a novel approach

A leaf spring, especially the longitudinal type is liable and persistent element in automotive suspension system. In the present scenario the composite materials are widely used in the automobile industries has shown a great interest in the replacement of steel spring due to high strength by weight ratio. Previous investigations focused on stresses and displacement analysis of single leaf spring for different materials. The present work aims to design and analysis of leaf spring for two different cases by considering the Young's modulus to yield strength ratio. In the first case the analysis deals with the design and analysis of a single cantilever solid triangle beam which is an equivalent beam of a spring with three leaves having uniform strength. In the second case a 3-beams of rectangular cross section has been considered which is equivalent to a spring with three leaves. The analysis was carried out based on contact mechanics approach. The results were compared, that the fiberglass composite leaf spring is suitable for high loading capacity, reliability and efficiency.

Study Effects of Vehicle Velocity on a Road Surface Roughness Simulation

Road roughness is a broad term that incorporates everything from potholes and cracks to the random deviations that exist in a profile. To build a roughness index, road irregularities need to be measured first. Existing methods of gauging the roughness are based either on visual inspections or using one of a limited number of instrumented vehicles that can take physical measurements of the road irregularities. This paper presents used a quarter car model (passive suspension System in 206 Peugeot) in according road classification ISO 2631-1 is achieved road roughness interval in form of optimization method Gamma (4p) distribution as PSD function in different constant speed of car (34, 70 and 100 Km/h) by using Matlab Code. Finally, to have accurate results and to describe effect of vehicle velocity on irregularity surfaces incoming Automotive Suspension System, are compared road roughness in terms of travel length and PSD function in terms of Frequency Hz. Keyword: Road Roughness, PSD function, Vehicle Velocity, Gamma (4p) distribution.