Suspension Test Rig Research Articles

로드노이즈 성능 예측을 위한 현가장치 하드포인트의 가진력 직접 측정법에 대한 실험적 평가

NVH engineering has become a hot issue due to radical technology changes and development in automotive industry since customers' expectations and needs for their vehicle is taken to a higher level. However, the source identification and quantification of the road noise within a vehicle is still not at the level where it needs to be to meet their expectations due to its' complex transfer path and difficulties in path optimization. The primary focus of this research is on direct force obtaining method at suspension hard points using suspension test rig. Directly obtained forces at suspension to body mounting points are critical and crucial for determining the effects of design changes of the suspension has on road noise performance. Direct force obtaining method has its limitation in sensor installation within an actual vehicle therefore, many has been indirectly calculating forces using full matrix inversion method or dynamic stiffness method. In this study, to circumvent this limitation, a suspension rig is used. Then, the suspension rig is verified through a comparative analysis of its dynamic behavior between the actual vehicle by cleat test on chassis dynamometer.

Energy Harvesting and Regeneration from the Vibration of Suspension System

Two conceptual designs of energy regenerative suspension have been developed using commercial computer aided design (CAD) software. The designs are based on the available conventional suspension. They consist of basic magnet and coil for electrical energy regeneration and additional components for magnet support and coil winding circular holder. The selection of the design is based on weighted matrix which consists of reliability, cost, time consumption and weight. The score of the matrix is formulated based on relative weighted factor among the selections. All designs are fabricated using selected and available materials. The actual cost, time consumption and weight of the suspensions are compared with the theoretical weighted scores. Standard processes of cuttings, fittings and welding are performed in fabrication. Suitable magnet design is attached on the suspensions. The other moving part of the suspensions is attached by coil and coil holder. The suspensions are tested with various strokes and frequencies for feasibility studies and energy regeneration capability using suspension test rig. The evaluation of the suspensions is performed based on actual experimental results of voltage and power regenerated.

The Performance Development of the Mechanical Suspensions Test Rig

Mechanical suspension test rig is much cheaper, but is can not meet the requirements of the suspension in-depth study. The reason is that the frequency and amplitude of the bench is immutable. According to the requirements of practical use, the frequency and amplitude control equipment is designed to arbitrarily change the vibration frequencies of the left and right wheels,and it can change the vibration amplitude of the wheels with a range of 5~12mm. It can meet the suspension test requirements.

Development and Analysis of a Regenerative Shock Absorber for Vehicle Suspension

Only10-16% of the fuel energy is used to drive the car-to overcome the resistance from road friction and air drag.One important loss is the dissipation of vibration energy by shock absorber of the vehicle suspension due to road irregularity, vehicle acceleration and deceleration.A prototype of regenerative shock absorber (RSA)was developed and its performance was studied.The prototype of RSA mainly consists of a gear transmission system, one way bearing and an electromagnetic generator.The RSA’s damping coefficient, its capacity to absorb energy and its ability to regenerate electrical energy were measured for various input frequencies, amplitudes and electrical loads. A quarter car model which consists of the developed RSA,a mass anda spring with specific damping ratio of ζ=0.6 and ζ=0.8 was tested. The test was done using a quarter car suspension test rig to investigate the performance of suspension which uses RSA and the generated electrical energy from RSA. The results are reported and discussed in this article.

Dynamic Simulation and Analysis of a Dual-Link Suspension

Based on the multi-body dynamics theory, a rigid-flexible coupling dual-link suspension model is established. Belgium road motivate inputs gathered from a proving ground are imposed on both wheels through a suspension-test rig and then a simulation is carried out. Next, the model is verified and refined by the available field test results of rear axle vertical acceleration. At last, based on the validated suspension dynamic model, a comprehensive dynamic load simulation is performed and different kinds of load form of suspension components are analyzed. This research could provide reference for measure point selection of load spectrum acquisition.

Semi-active hydro-gas suspension system for a tracked vehicle

A semi-active hydro-gas suspension is proposed for a tracked vehicle to improve ride comfort performance, without compromising the road holding and load carrying capabilities of the passive suspension. This is achieved through an active damper used in parallel with a gas spring. The suspension damper parameters are varied by a control mechanism based on sky-hook damping theory, which alters the flow characteristics. A damper prototype has been developed, tested for its flow characteristics, after which it has been integrated into an existing hydro-gas suspension system. An analytical model has been proposed from first principles rather than developing a phenomenological model based on experimental characteristics. This model is validated with experiments carried out on a suspension test rig. In order to compare the performance with the original passive system, an in-plane vehicle model is developed and the simulations clearly show that the semi-active system performance is superior to the passive system.

An insight into linear quarter car model accuracy

The linear quarter car model is the most widely used suspension system model. A number of authors expressed doubts about the accuracy of the linear quarter car model in predicting the movement of a complex nonlinear suspension system. In this investigation, a quarter car rig, designed to mimic the popular MacPherson strut suspension system, is subject to narrowband excitation at a range of frequencies using a motor driven cam. Linear and nonlinear quarter car simulations of the rig are developed. Both isolated and operational testing techniques are used to characterise the individual suspension system components. Simulations carried out using the linear and nonlinear models are compared to measured data from the suspension test rig at selected excitation frequencies. Results show that the linear quarter car model provides a reasonable approximation of unsprung mass acceleration but significantly overpredicts sprung mass acceleration magnitude. The nonlinear simulation, featuring a trilinear shock absorber model and nonlinear tyre, produces results which are significantly more accurate than linear simulation results. The effect of tyre damping on the nonlinear model is also investigated for narrowband excitation. It is found to reduce the magnitude of unsprung mass acceleration peaks and contribute to an overall improvement in simulation accuracy.

Industrial digital control in undergraduate fluid power courses: a student-centred approach using an active suspension test rig

The evolution of software techniques applicable to fluid power systems has now resulted in almost commonplace industrial application solutions that were not possible 5-10 years ago. This is causing some discussion regarding the way undergraduate fluid power courses should develop with respect to the inclusion of these new technologies. This paper shows how two new activities, real-time control of an active suspension and performance monitoring, have been developed by students for students and the way they will be brought into an undergraduate degree scheme.

Fault Detection for Lateral and Vertical Vehicle Dynamics

Model based methods have been developed for sensor and process fault detection and diagnosis of an active hydraulic suspension system. Dynamic mathematical models are used for describing the lateral vehicle behavior and vertical behavior of an active suspension in real-time. Based on parameter estimation and parity equations symptoms for fault detection are generated. This is followed by fault diagnosis with fuzzy logic. Results are presented for measurements with a vehicle and a suspension test rig. The fault detection method is intended to be used for mechatronic suspensions, driver assistance, and vehicle control systems.

Adaptive robust force control for vehicle active suspensions

AbstractIn this paper, the modular adaptive robust control (MARC) technique is applied to design the force loop controller of an electro‐hydraulic active suspension system. A key advantage of this modular design approach lies in the fact that the adaptation algorithm can be designed for explicit estimation convergence. The effect of parameter adaptation on force tracking performance can be compensated and thus it is possible to guaranteed certain control performance. Experimental results from a quarter‐car active suspension test rig show that when realistic external disturbances and measurement noises exist, the modular design achieves a better estimate than the non‐modular ARC design. The improved estimation was found to result in control signals with slightly lower magnitude while maintaining similar tracking performance. Copyright © 2004 John Wiley & Sons, Ltd.

Automotive Applications and Simulations of a New High Bandwidth Servo-Valve

A new multipurpose servo valve has been designed. Its direct-drive architecture enables high bandwidth, low cost and its use in automotive conditions. The validity of such affirmations has been verified on a test rig reproducing three main automotive applications. Simultaneously, a Bond-Graph model of the servo valve has been created. To verify its precision, it was inserted in the suspension test rig Bond-Graph model. Simulation and experience provide similar results. The potentiality of such actuator is demonstrated by the insertion of its model in a W hydropneumatic active suspension model.

Observer-Based Identification of Nonlinear System Parameters

This paper deals with an observer-based nonlinear system parameter identification method utilizing repetitive excitation. Although methods for physical parameter identification of both linear and nonlinear systems are already available, they are not attractive from a practical point of view since the methods assume that all the system, x, and the system input are available. The proposed method is based on a “sliding observer” and a least-square method. A sufficient condition for the convergence of the parameter estimates is provided in the case of “Lipschitz” nonlinear second-order systems. The observer is used to estimate signals which are difficult or expensive to measure. Using the estimated states of the system with repetitive excitation, the parameter estimates are obtained. The observer based identification method has been tested on a half car simulation and used to identify the parameters of a half car suspension test rig. The estimates of nonlinear damping coefficients of a vehicle suspension, suspension stiffness, pitch moment inertia, equivalent sprung mass, and unsprung mass are obtained by the proposed method. Simulation and experimental results show that the identifier estimates the vehicle parameters accurately. The proposed identifier will be useful for parameter identification of actual vehicles since vehicle parameters can be identified only using vehicle excitation tests rather than component testing.

Analysis, modelling-and control of an advanced automotive self-levelling suspension system

The paper is concerned with the analysis, modelling and control of a prototype self-levelling active suspension system for road vehicles. Motivation for the work is given by considering some of the fundamental performance limitations within which all traditional passive designs are constrained to operate. Self-levelling systems are presented as a viable engineering compromise from ideal "fully active" designs which are currently regarded as impractical owing to their associated cost and fuel-consumption penalties. Early analyses are concerned with quantifying the disturbance sources affecting automotive suspension systems: irregularities in road surface elevation and dynamic (inertial) forces resulting from driving manoeuvres such as steering and braking. Analysis of the suspension system itself includes linear and nonlinear dynamic modelling of a single wheel station or "quarter car" for which a suitable controller is designed. The analytical work is supported for both the active and passive suspensions by experimental results taken from a full-scale hydraulically powered quarter-car suspension test rig.

Adaptive observers for active automotive suspensions: theory and experiment

An adaptive observer is developed for a class of nonlinear systems. Conditions for convergence of state and parameter estimates are presented. The developed theory is used for observer-based parameter identification in the active suspension system of an automobile. A realistic model of the suspension system incorporating the dynamics of the hydraulic actuator is used. The observer is used to adapt on dry friction which is usually present in significant magnitudes in hydraulic actuators. The observer can also be used to adapt on spring stiffnesses, viscous damping and hydraulic bulk modulus. A special adaptive observer is proposed for identification of the sprung mass of the automobile. Since the sprung mass depends on the number of passengers and the load on the automobile, it needs to be regularly updated. The adaptive observers use measurements from two accelerometers and an LVDT. They yield good experimental performance when implemented on a half-car suspension test rig. >

Observer Design for Electronic Suspension Applications*

SUMMARY This paper proposes a new methodology for designing observers for automotive suspensions. Automotive suspensions are disturbance-affected dynamic systems. Semi-active suspensions are bilinear while active suspensions with hydraulic actuators are nonlinear. The proposed methodology guarantees exponentially convergent state estimation for both these systems. It uses easily accessible and inexpensive measurements. The fact that sprung mass absolute velocity of the suspension cannot be estimated in an exponentially stable manner with such measurements is also demonstrated. Controllers using estimated states are implemented experimentally on the Berkeley Active Suspension Test Rig. Experimental results for two cases are presented : use of observer states to improve ride quality in an active suspension and use of observer states to reduce dynamic tire loading in a semi-active heavy vehicle suspension.

SEMI-ACTIVE SUSPENSIONS - A COMPARISON BETWEEN THEORY AND EXPERIMENTS

SUMMARY A full-scale half car suspension test rig is used to evaluate the performance of switchable dampers in semi-active control. A theoretical model is developed for the test rig and its parameters are identified. Two types of switchable shocks are used. A low bandwidth tri-state damper originally designed for manual setting changes is shown to be too slow for real-time ride quality improvement Semi-active control is successfully demonstrated with a high bandwidth multi-state damper. Conventional ON-OFF, optimal ON-OFF, optimal multi-state control and a robust form of multi-state control are implemented and compared. Semi-active control is shown to give a performance as good as the best of all available passive states at every frequency. Trends in the experimental results are accurately predicted by the theoretical model

Dual-processor controller with vehicle suspension applications

A dual-processor controller suitable for computation-intensive control and signal-processing algorithms is described. The controller is built around a general-purpose microcontroller and a digital signal processor (DSP). The main goal of the design is efficient computation of mathematically oriented algorithms with the ability to interface with sensors and actuators. The effectiveness of controllers incorporating DSP chips is demonstrated with two applications of suspension-sensor data frequency-domain analysis and state estimation of a quarter-car suspension test rig. >