Vehicle Suspension Performance Research Articles

Influences of the electromagnetic regenerative dampers on the vehicle suspension performance

Conventional vehicle suspensions suppress vehicle vibrations by dissipating the vibration energy into unrecyclable heat with hydraulic dampers. This can be a considerable amount of energy which is worthy of attention for energy recovery. Electromagnetic regenerative dampers, or shock absorbers, are proposed to harvest this dissipated energy and to improve the fuel efficiency. The suspension dynamics with these regenerative dampers can be significantly different from the suspension dynamics with conventional dampers. First, different from conventional hydraulic dampers, the electromagnetic regenerative dampers have a significantly higher inertia, which is introduced by the electromagnetic generator. This has an important impact on the suspension dynamics. Second, the damping coefficient of electromagnetic dampers is related to the electric load connected to the output of the generator and can be controllable. Although various concepts have been proposed, the influences of these types of regenerative damper on the vehicle dynamics have not yet been thoroughly investigated. This paper models two types of rotational electromagnetic regenerative damper, with and without a mechanical motion rectifier, and analyzes their influences on the vehicle suspension performance in comparison with those of the conventional damper. The modeling in this paper also considers the case when the tires lose contact with the ground. Simulations were carried out with step road profile excitations and road profile excitations defined by the International Standardization Organization in order to evaluate the influences of the equivalent inertia mass and the equivalent damping coefficient. The results showed that, with an optimized equivalent inertia mass, both types of electromagnetic damper can achieve better ride comfort performances than a constant damper does. In addition, the mechanical motion rectifier mechanism can significantly improve the ride comfort and the road-handling performance of electromagnetic regenerative dampers by reducing the negative effect of the amplified generator inertia. In addition, the energy-harvesting potential of the presented dampers under road profile excitations defined by the International Standardization Organization was evaluated.

Influence of Spring Ratio on Variable Stiffness and Damping Suspension System Performance

The variable stiffness and damping (VSVD) suspension system offers an interesting option to improve driver comfort in an energy efficient way. The aim of this study is to analyze the influence of the spring ratio on the VSVD. The realization of the VSVD is obtained by the application of variable damping with magnetorheological (MR) damper. In this study, the nonlinear damping force characteristic of the MR damper is modeled with the Bouc-Wen model and the road disturbance is modeled by a stationary random process with road displacement power spectral density. It is shown from simulation that VSVD has a potential benefit in improving performance of vehicle suspension.

Novel evaluation method of vehicle suspension performance based on concept of wheel turn center

The current research of suspension performance evaluation is mixed in the evaluation of vehicle handling and ride comfort. However, it is lack of a direct and independent evaluation method for suspension performance. In this paper, a novel wheel turn center method is proposed to evaluate the suspension performance. This method is based on the concept and application of wheel turn center (WTC) and sprung mass turn center (SPTC). The vehicle body and each wheel are regarded to be independent rigid bodies and have their own turn centers which reflect respective steering motions and responses. Since the suspension is the link between vehicle body and wheels, the consistence between the sprung mass turn center and the wheel turn center reflects the effect and performance of the suspension system. Firstly, the concept and appropriate calculation method of WTC and SPTC are developed. Then the degree of inconsistence between WTC and SPTC and the time that they achieve consistence, when the vehicle experiences from transient steering to steady steering state, are proposed to evaluate suspension performance. The suspension evaluation tests are conducted under different vehicle velocities and lateral accelerations by using CarSim software. The simulation results show that the inconsistence of steering motion between vehicle body and wheels are mainly at high speeds and low lateral accelerations. Finally, based on the proposed evaluation indexes, the influences of different suspension characteristic parameters on suspension performance and their matches to improve steering coordination are discussed. The proposed wheel turn center method provides a guidance and potential application for suspension evaluation and optimization.

Effects of Tyre Pressure on Vehicle Suspension Performance

Incorrect inflation pressures in tyres affects the vehicle handling, passenger comfort and braking conditions in addition to causing a reduction in fuel efficiency and tyre life. To address this problem, mathematical models have been produced and an experimental validation has been carried out. The models were developed with 7-DOF, for a full car system, using MATLAB programs. In the simulation study, the suspension faults have been considered by running the models with a range of inflation pressures at four conditions i.e. at standard pressure (2.3bar) and 1.5bar on the passenger wheel, driver wheel and front wheels. In each case, an analysis was carried out on the performances of the suspension in terms of ride comfort, road handling and stability of the vehicle followed by the presentation of the results obtained. In addition, the influence of parameter variations on transfer functions as a fault detection of suspension has been introduced. This approach has been used when detecting faults of vehicle tyres being under-inflated 35% and also to detect other suspension faults in the future.

Effects of Tyre Pressure on Vehicle Suspension Performance

Incorrect inflation pressures in tyres affects the vehicle handling, passenger comfort and braking conditions in addition to causing a reduction in fuel efficiency and tyre life. To address this problem, mathematical models have been produced and an experimental validation has been carried out. The models were developed with 7-DOF, for a full car system, using MATLAB programs. In the simulation study, the suspension faults have been considered by running the models with a range of inflation pressures at four conditions i.e. at standard pressure (2.3bar) and 1.5bar on the passenger wheel, driver wheel and front wheels. In each case, an analysis was carried out on the performances of the suspension in terms of ride comfort, road handling and stability of the vehicle followed by the presentation of the results obtained. In addition, the influence of parameter variations on transfer functions as a fault detection of suspension has been introduced. This approach has been used when detecting faults of vehicle tyres being under-inflated 35% and also to detect other suspension faults in the future.

Effects of Tyre Pressure on Vehicle Suspension Performance

Incorrect inflation pressures in tyres affects the vehicle handling, passenger comfort and braking conditions in addition to causing a reduction in fuel efficiency and tyre life. To address this problem, mathematical models have been produced and an experimental validation has been carried out. The models were developed with 7-DOF, for a full car system, using MATLAB programs. In the simulation study, the suspension faults have been considered by running the models with a range of inflation pressures at four conditions i.e. at standard pressure (2.3bar) and 1.5bar on the passenger wheel, driver wheel and front wheels. In each case, an analysis was carried out on the performances of the suspension in terms of ride comfort, road handling and stability of the vehicle followed by the presentation of the results obtained. In addition, the influence of parameter variations on transfer functions as a fault detection of suspension has been introduced. This approach has been used when detecting faults of vehicle tyres being under-inflated 35% and also to detect other suspension faults in the future.

Ride Comfort Performance of Active Vehicle Suspension with Seat Actuator Based on Non-Fragile H∞ Controller

The purpose of this paper is to investigate an active seat suspension system with two active actuators using a non-fragile robust control strategy. A simple deterministic vibration model of human body is added to the seat suspension dynamical model in order to make the modeling more accurate. Desired controller is obtained by solving a linear matrix inequality formulation by considering the vertical body acceleration as measurement signal. Finally, the effect of the seat actuator and controller gain variations on the closed-loop system performance is investigated numerically for two deterministic external excitations: bump and a realization of Gaussian white noise. Simulations show that the seat actuator has a noticeable effect on the seat suspension performance especially under random disturbances.

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.

Optimization of the Laws of Control the Parameters of Two-axle Vehicle Suspension Using STABCON 2.0 System Software

The article includes the brief information on the application suites Stabcon 2.0. With Stabcon the authors made ​​the statement and solution of the task of optimization of two-axle vehicle suspension performance in different road conditions. The characteristics of the design parameters of the suspension control two-axle vehicle are described in the article.

Road-frequency adaptive control for semi-active suspension systems

In this paper, a road-frequency adaptive control for semi-active suspension systems is investigated. The control aims to improve the vehicle suspension performance (ride comfort and wheel handling) for all frequency regions of road disturbances. In order to achieve this aim, the control law is extended from the conventional skyhook control, and the controller gains are scheduled for various frequency regions of road disturbances. By using the data measured from a relative displacement sensor, a state estimator based on a Kalman filter for estimating the required state variables is designed. Road disturbance frequencies are estimated by using a first order zero-crossing algorithm. The efficiency of the proposed control is shown through numerical simulations.

Impact of inerter nonlinearities on vehicle suspension control

This paper discusses the nonlinear properties of inerters and their impact on vehicle suspension control. The inerter was recently introduced as an ideal mechanical two-terminal element, which is a substitute for the mass element, where the applied force is proportional to the relative acceleration across the terminals. Until now, ideal inerters have been applied to vehicle, motorcycle and train suspension systems, in which significant performance improvement was achieved. However, due to the mechanical construction, some nonlinear properties of the existing mechanical models of inerters are noted. This paper investigates the inerter nonlinearities, including friction, backlash and the elastic effect, and their influence on vehicle suspension performance. A testing platform is also built to verify the nonlinear properties of the inerter model.

Road test evaluation of vibration control performance of vehicle suspension featuring electrorheological shock absorbers

This work presents road test results for vibration control of a vehicle suspension system equipped with continuously controllable electrorheological (ER) shock absorbers. The test vehicle is a mid-sized passenger car whose suspension systems are typical Macpherson strut types for the front part and multilink types for the rear part. The four ER shock absorbers (two for the front suspension and two for the rear suspension) are devised based on design specifications for the test vehicle and their damping forces are experimentally evaluated with respect to the electric field. The ER shock absorbers and conventional spring elements are then assembled into suspension systems. Prior to undertaking the road test, the front ER suspension is applied to the quarter-car facility in order to validate control performance of the skyhook controller embedded in on-chip hardware. Subsequently, the full-vehicle model incorporating four ER suspensions is established and the skyhook control gains are determined in an optimal manner. The controller is then implemented on the test vehicle which is equipped with several sensors, a data acquisition system, and high-voltage amplifiers. Control performances are evaluated under various road conditions (bump, long waved, rugged, paved, and unpaved) and presented in both time and frequency domains.

Fuzzy and adaptive fuzzy control for the automobiles’ active suspension system

Two typical criteria for good vehicle suspension performance are their ability to provide good road handling and increased passenger comfort. The main disturbance affecting these two criteria is terrain irregularities. Active suspension control systems reduce these undesirable effects by isolating car body motion from vibrations at the wheels. This paper describes fuzzy and adaptive fuzzy control (AFC) schemes for the automobile active suspension system (ASS). The design objective is to provide smooth vertical motion so as to achieve the road holding and riding comfort over a wide range of road profiles. The efficacy of the proposed control schemes is demonstrated via simulations. With respect to the optimal linear quadratic regulator (LQR), it is shown that superior results have been achieved by the AFC.

Optimal Active Control of Vehicle Suspension System Including Time Delay and Preview for Rough Roads

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.

Optimization and Performance Enhancement of Active Suspensions for Automobiles under Preview of the Road

SUMMARY The problem of deriving control laws which minimize specified performance indices for a vehicle moving on a rough surface with preview of the surface elevation is considered. The approach is based on linear optimal tracking theory and consequently the system elements are taken to be linear and the performance index is constrained to be of quadratic form. The ideas of overtaking optimality are applied to the problem in order to achieve a closed form solution for the control. Then, using the control laws derived, computer simulations of performance are conducted and time histories are shown. In the absence of limitations on either processing or actuator speeds, and for cases in which the preview is sufficient to give good control laws, the value of the preview in enhancing vehicle suspension performance is assessed. Comparisons are made with results in the literature.