Suspension Damping Research Articles

Adaptive online estimation of centre of gravity height for commercial vehicles

A novel parameter error driven robust estimation method is proposed for online estimation of centre of gravity (CG) height of a tour bus vehicle. Unlike the commonly used recursive least squares (RLS) method, a parameter error driven updating law is synthesised to ensure improved performance in terms of steady-state error and robust convergence. The stability of the proposed estimation method is illustrated using the Lyapunov approach. The proposed CG estimation method is based on directly measurable lateral acceleration and relative roll angle of the sprung mass, while the high order signals are eliminated using the filtering approach. The validity of the proposed estimation method is illustrated through implementations in TruckSim platform. Simulation results show that the proposed estimation method can yield accurate online estimation of the CG height, together with effective suspension roll stiffness and damping properties.

Adaptive online estimation of centre of gravity height for commercial vehicles

A novel parameter error driven robust estimation method is proposed for online estimation of centre of gravity (CG) height of a tour bus vehicle. Unlike the commonly used recursive least squares (RLS) method, a parameter error driven updating law is synthesised to ensure improved performance in terms of steady-state error and robust convergence. The stability of the proposed estimation method is illustrated using the Lyapunov approach. The proposed CG estimation method is based on directly measurable lateral acceleration and relative roll angle of the sprung mass, while the high order signals are eliminated using the filtering approach. The validity of the proposed estimation method is illustrated through implementations in TruckSim platform. Simulation results show that the proposed estimation method can yield accurate online estimation of the CG height, together with effective suspension roll stiffness and damping properties.

Vibration research of heavy trucks. Part 1: Sensitivity analysis of dynamic parameters on ride comfort

In order to study the influence of heavy truck dynamic parameters on the vehicle’s ride comfort under the random road excitation, the weighted RMS (root-mean-square) acceleration responses of the vertical driver’s seat and cab pitch angle are chosen as objective function, a dynamic model of the vehicle with 10 degrees of freedom is established to simulate and analyze the results. The influence of different parameters of all the suspension systems of the vehicle, such as the stiffness and damping of the suspensions of the seat, cab, vehicle, and wheel, on the vertical driver’s seat and cab pitch angle are respectively analyzed. The study results show that the influence of the stiffness and damping parameters in the suspension systems on the vehicle ride comfort is very obvious. The vehicle’s ride comfort changes worse with the increase of the suspension stiffness and the reduction of the suspension damping, and vice versa. The study proposes an optimal range of the stiffness and damping parameters for the optimal design and control of the vehicle suspension systems, concurrently, the study can also provide a theoretical basis for the suspension system designed for heavy trucks.

Multiobjective Optimization of Nonlinear Active Suspension System with Time-Delayed Feedback

Considering the nonlinear properties of spring and damping of suspension, a quarter-car model with time-delayed control is established. The Routh–Hurwitz stability criterion and stability switching method are used to analyze the stability of the system and obtain the stability region diagram. The multiobjective optimization function is established by considering the ride comfort, driving safety, and handling stability. The optimal control parameters are obtained by the optimization and simulation of the system under harmonic excitation and random excitation. In addition, the responses of the active suspension system with optimal time-delay control and the passive suspension system without control are compared. The results show that the active suspension system with time-delay displacement feedback control can reduce the vibration of the system, and there is an optimal feedback parameter combination to optimize the vehicle running state. The design of multiobjective function optimization proposed in this paper can improve ride comfort, driving safety, and handling stability and provide guidance for comprehensively improving vehicle performance.

Dynamic performance analysis and parameters perturbation study of inerter–spring–damper suspension for heavy vehicle

Inerter, a new type of mass element, can increase the inertia of motion between two endpoints. In order to study the dynamic inertia effect of inerter–spring–damper suspension for heavy vehicle on ride comfort and road friendliness, the inerter–spring–damper suspension is applied and its mechanism is studied. This paper establishes a half vehicle model of inerter–spring–damper suspension for heavy vehicle. The parameters of inerter–spring–damper suspension for heavy vehicle are optimized by multi-objective genetic algorithm and system simulations are carried out. The parametric influence of different spring stiffness, damping coefficient, inertance, and load on suspension performance is also studied. The simulation results demonstrate that the centroid acceleration and pitch angular acceleration are improved by 24.90% and 23.54%, respectively, and the comprehensive road damage coefficient is reduced by 4.05%. The results illustrate that the inerter–spring–damper suspension can decrease the vertical vibration of vehicle suspension especially in low frequency and reduce the road damage. The analyses of suspension parameters perturbation reveal their different effect laws of the different wheels on vehicle ride comfort and road friendliness, which provide a theoretical basis for setting parameters of inerter–spring–damper suspension.

Simulation Research on the Driving Stability of Articulated Vehicle Based on ADAMS

The vehicle dynamical model was established by taking the articulated vehicle driven electrically as the research object, and the vehicle dynamical simulation was carried out by using ADAMS. The effects of different center of mass position, steering parameters, mass, lateral stiffness of tire, suspension stiffness and damping on the driving stability of articulated vehicle were analyzed. The simulation results showed that the driving stability of the articulated vehicle was improved by factors such as the position of the center of mass closing to the hinged point, increasing the steering stiffness and damping, reducing the lateral stiffness of the tire, increasing the suspension stiffness and damping, appropriately increasing the rear body mass, etc. This study provided a reference for the design and improvement of the vehicle.

Effect of the asymmetry of suspension damping on the ride comfort of railway vehicles

ABSTRACT In terms of reliability, the damper represents the critical element of the suspension in the rail vehicle. A damper failure brings about a reduction in the damping of the suspension it belongs to, thus leading to the asymmetry of the suspension damping in the vehicle. The paper presents an analysis of the effect that the asymmetry of the secondary suspension damping has on the vertical vibration behaviour in the vehicle carbody and on the ride comfort, while using to that purpose the results derived from numerical simulations. The characteristics of the vibration behaviour for the resonance frequencies of the carbody dominant vertical modes are pointed out via the power spectral density of the carbody acceleration, which is weighted by the function of the sensitivity of the human body to the vertical vibrations. The ride comfort is assessed based on the ride index comfort calculated in three carbody reference points – at the centre and above the two bogies.

Dynamic modeling, simulation and experimental investigation on cycling-trainers equipped with suspensions considering human biomechanical characteristics

At present, to meet the innervation and the comfort of cycling-trainers, the trend of deploying suspension system is still upwards. However, there is no reliable dynamic model for cycling-trainers equipped with suspension systems, and the influence of the suspension damping on the dynamic responses needs to be explored. In this paper, based on a commercially available cycling-trainer with suspension systems, a non-linear dynamic model of trainer-human coupled system was established. According to the bench test, the damping coefficient of suspension dampers was measured. By the cycling test, the dynamic model was validated. The test values of the vertical acceleration of the human lower trunk are in agreement with the simulation values, in which the maximum deviation is less than 15.0 % and the root mean square deviation is less than 8.0 %. Based on the model, the influences of the damper damping on the dynamic responses were analyzed. The results show that the influence laws of the suspension damping characteristics on the human body responses vary greatly under the different riding frequencies, and an optimal damping exists to avoid excessive fatigue caused by vibration under the medium and low frequency riding conditions. The established model and the revealed rules can provide useful reference for the suspension design and optimization of cycling-trainers.

Optimal response of half car vehicle model with sky-hook damper using LQR with look ahead preview control

This paper addresses the problem of determining the optimal parameters of a sky-hook damper type suspension in the control of the stationary random response of half car vehicle models traversing a rough road with constant velocity. The feedback control scheme is realized by approximating the sky-hook damper strategy, and the optimal parameters of the sky-hook damper are obtained by equating the sky-hook damper suspension force with that of a fully active suspension force using linear quadratic regulator with preview control (LQR with preview control). Results show that the overall performance of the sky-hook damper approximately 99% matches with performance of LQR with preview control (look ahead preview control) over a specified vehicle velocity range.

Study on an Energy-Harvesting Magnetorheological Damper System in Parallel Configuration for Lightweight Battery-Operated Automobiles

Suspension dampers are extremely critical for modern automobiles for absorbing vibrational energy while in operation. For years now, the viscous passive damper has been dominant. However, there is a constant need to improve and revolutionize the damping technology to adapt to modern road conditions and for better performance. Controlled shock absorbers capable of adapting to uneven road profiles are required to meet this challenge and enhance the passenger comfort level. Among the many types of modern damping solutions, magnetorheological (MR) dampers have gained prominence, considering their damping force control capability, fast adjustable response, and low energy consumption. Advancements in energy-harvesting technologies allow for the regeneration of a portion of energy dissipated in automotive dampers. While the amount of regenerated energy is often insufficient for regular automobiles, it could prove to be vital to support lightweight battery-operated vehicles. In battery-operated vehicles, this regenerated energy can be used for powering several secondary systems, including lighting, heating, air conditioning, and so on. This research focuses on developing a hybrid smart suspension system that combines the MR damping technology along with an electromagnetic induction (EMI)-based energy-harvesting system for applications in lightweight battery-operated vehicles. The research involves the extensive designing, numerical simulation, fabrication, and testing of the proposed smart suspension system. The development of the proposed damping system would help advance the harvesting of clean energy and enhance the performance and affordability of future battery-operated vehicles.

Research on ride comfort analysis and hierarchical optimization of heavy vehicles with coupled nonlinear dynamics of suspension

The fact that the calculation model and optimization method are critical to the optimization efficiency of ride comfort. To improve the reliability of this process for heavy vehicles, this article proposes a systematic modelling method that is based on the coupled nonlinear dynamics of suspension components and a hierarchical optimization method that considers passenger comfort, cargo safety, and parts fatigue. Nonlinear mathematical models of leaf springs and dampers are established first. A novel model of ride comfort is then developed by integrating the nonlinear mathematical models with a conventional vibration model formulated according to Newton's second law. According to experimental observations, the novel model shows greater accuracy than the conventional one. Subsequently, the influences of suspension parameters on ride comfort are clarified with an integrated multi-software method, illustrating steering suspension stiffness and cabin rear suspension damping are significant factors affecting ride comfort. Finally, a hierarchical optimization model is developed to enhance ride comfort and minimize the amplitude of vibrations. The optimized vibrations show average reductions of 31.1% and 17.0% for the seat rail and sprung centroid, respectively.

A State-Of-The-Art Review of Car Suspension-Based Piezoelectric Energy Harvesting Systems

One of the most important techniques for energy harvesting is the clean energy collection from the ambient vibration. Piezoelectric energy harvesting systems became a hot topic in the literature and attracted most researchers. The reason behind this attraction is that piezoelectric materials are a simple structure and provide a higher power density among other mechanisms (electromagnetic and electrostatic). The aim of this manuscript is to succinctly review and present the state of the art of different existing vibrational applications utilizing piezoelectric energy harvesting technique. Meanwhile, the main concentration is harvesting energy from a vehicle suspension system. There is a significant amount of dissipated energy from the suspension dampers that is worthy of being harvested. Different mathematical car models with their experimental setup are presented, discussed, and compared. The piezoelectric material can be mounted in different locations such as suspension springs, dampers, and tires. The technique of implementing the harvester and the amount of power harvested from each location are analyzed. The evaluation of the electrical harvesting circuits and different storage devices for the harvested power are also discussed. The paper will also shed light on the variety of potential applications of the harvested energy.

Design, modeling, and control of a magnetorheological rotary damper for scissor seat suspension

This research investigates the design, modeling, and control of an improved magnetorheological rotary damper for seat suspension. A magnetorheological damper with optimized flux path is developed to improve the distribution of magnetic field. Its dynamic damping characteristics are tested by MTS machine under sinusoidal excitations. To describe the nonlinear damping characteristics of magnetorheological damper, a hysteretic model based on backbone curve is selected by comparing with other models. To verify the feasibility of seat suspension with the proposed magnetorheological damper, the simulated analysis and experimental tests are conducted. A dynamic model of scissor seat suspension with rotary damper is constructed and simplified. The performances of semi-active system show that the seat suspension with the proposed damper can reduce vibration efficiently.

Simulation of nonlinear vibration responses of cab system subject to suspension damper complete failure for trucks

The strong vibration responses of the cab system can be restrained by the damper force and the friction of the suspensions for trucks. After the failures of dampers, especially in the case of the complete failure, the anti vibration effect of the friction is prominent. However, the nonlinear vibration response characteristics of the cab subject to the damper complete failure have not been revealed. In order to reveal the nonlinear vibration response characteristics, a dynamic model of the cab system was established and its vibration equations were given. The friction forces existing in the suspensions were determined by the bench test. The influences of the friction forces on the cab vibration under different amplitude harmonic inputs were investigated when the dampers completely fail. The cab vertical displacement changes with the excitation amplitude and the vibration represents various motion states, including the periodic motion, the quasi-periodic motion, and the chaotic motion. The simulation results show that when the dampers fail, the proper friction forces help to suppress the quasi-periodic motion and the chaotic motion of the cab and to reduce the amplitude of the periodic motion. The proper friction forces can make the cab movement far away from the chaos area. They also help to avoid the fatigue damage of the cab floor and suspension parts to improve the service life of the suspension parts and to reduce the maintenance cost of the cab suspensions.

Simulation Analysis and Optimization of a Passenger Car Ride Comfort

The vehicle ride comfort research is an important part of the vehicle development process. This paper takes a passenger car as the research object, establishes the vehicle rigid-flexible coupling ride comfort simulation model based on ADAMS, and simulates the vertical vibration acceleration time domain curve at the driver‘s position. Through the derivation of the theoretical formula, the corresponding weighted vibration level is obtained. Next, the weighted vibration level of the front seat is used as the measurement index. The stiffness of the front suspension torsion bar spring and the damping of the front and rear suspension dampers are selected as the optimization variables to optimize ride comfort. The optimization of the performance makes the peak of vertical acceleration vibration response significantly reduced, which has certain practical value.

Study on Steady-State Responses of High-Speed Vehicle Using Infinite Long Track Model

The coupled vehicle/track dynamic model is formulated through integrating a high-speed rail vehicle model with a slab track model via the wheel/rail contact model. The sliding window method is improved using the least square criterion to simulate the vehicle travelling along the infinite long track. The steady-state responses of a high-speed vehicle induced by the discrete sleepers and slab segments are investigated through numerical simulation and analysis of the experimental results. Also the validity of the coupled vehicle/track model is examined through comparing the simulation results with those acquired from field test measurements. The experimental and numerical results show that the wheel/rail contact forces fluctuate considerably as long as the sleeper passing frequency approaches the frequency of P2 resonance (wheelset and rail bouncing in phase on the slab). Increasing the damping of rail pads and primary suspension can lower the steady-state response amplitudes at the resonance region. The oscillations in the wheel/rail normal forces arising from the discrete slab segment excitation can be reduced by increasing the support stiffness of the CAM (cement asphalt mortar) layer under the slab.

Calculation of the hydro-pneumatic suspension damper

AnnotationThe paper considers general approaches to the design and calculation of the characteristics of hydropneumatic dampers that can be used in the suspensions of mobile cars. It is paid particular attention to the determination of the main hydraulic characteristics of the flow part of the damper, including a direct-acting belt valve, based on numerical simulation.

Rationalization of parameters of hydraulic dampers of a carriage

The possibility of the car dynamic performance improvement is studied through structural changes (modernization) of the passenger bogie. Based on the calculations of the natural oscillations of the car, the critical values were determined and rational values of the damper resistance coefficient were chosen for vertical and lateral vibrations. It was concluded that with the forced spatial fluctuations of a carriages on KCCW-CRI bogies the required damping value of the vertical oscillations should be twice as large as for the lateral ones; important factors in damping of the car oscillations are the central suspension dampers. The rational angle of installation of the hydraulic damper in the central suspension and the use of separate action in the central suspension of hydraulic dampers are justified. The proposed version of the modernization of the bogie can improve the smoothness indicators of the car by 25-30%.

Virtual Sample analysis of concomitance fork’s stability and passing capacity

Based on such factors as positioning parameters, quality characteristics, stiffness and damping of suspension, steering train, drive train and tire, a multiple-body dynamics model of 14 DOF for one accompanying forklift is established with the 3D models and ADAMS software. In view of the driving environments of classified highways and fourth-class roads, four parameters including the speed, tilt stabilization angle, vertical tilt stability angle and channel width of the accompanying forklift are calculated, and high-speed driving stability and channel pass ability are analyzed and predicted during the design stage. The analysis results are useful for the design optimization of the traction rod and can provide a theoretical basis for the development of similar products.

Quantitative Research on Contribution Degree of Vibration Affecting Factors of Vehicle Suspension System Based on Robustness Analysis

Suspension system is the key component affecting vehicle ride comfort and finding out the main factors affecting suspension system vibration is the precondition of controlling suspension system vibration and improving vehicle comfort. Based on the principle of robustness analysis, the robustness analysis process of suspension system vibration influencing factors is constructed, in order to solve the problem, the three levels of front suspension stiffness, front suspension damping, rear suspension stiffness and rear suspension damping are selected, the experiment design scheme is adopted, power Spectrum of Class A road is used as input excitation source for suspension system simulation, the weighted acceleration root mean square simulation experiment of suspension system vibration under the influence of multiple factors is carried out.