Suspension Displacement Research Articles

Improving stability and comfort of an in-wheel motor drive electric vehicle via active suspensions

This paper presents a method of a controller design to improve the handling and stability of an in-wheel motor drive electric vehicle using active suspensions with considerations of parameter uncertainties and control saturation. The construction of the mathematical model of vehicle suspensions combines active suspensions with vehicle lateral stability. Through the robust H∞ optimal control of active suspensions, the vehicle lateral stability has been improved and the vertical dynamic displacements of suspensions have been decreased. The uncertain parameters include the vehicle body mass, suspension spring stiffness and suspension damping coefficient. The control saturation considered results from the physical limitations of actuators. Active suspensions are designed with linear matrix inequalities (LMIs) feedback control method to attenuate the effect of the lateral acceleration on the roll angle and the suspension stroke. Simulation results show that the designed controller can improve vehicle handling and stability and has good robustness.

Damping force and energy recovery analysis of regenerative hydraulic electric suspension system under road excitation: modelling and numerical simulation.

The regenerative hydraulic electric suspension (RHES) is a new type of energy regeneration damper system based on the principle of vibration energy harvesting. This system can recover the vibration energy of suspension dissipated in the form of thermal energy when vehicle travels on the road. In previous studies about RHES system, the vehicle suspension displacement is defined as varieties of periodic waves, such as sinusoidal and so on. The energy harvesting performance of damper system can be explained and evaluated to some extent, but the influence of the actual excitation condition of the road is not fully considered when studying the RHES. This paper builds models of road profiles, quarter car and power regeneration based on the proposed RHES system. Furthermore, the change laws of performance with the varies of road class, motor displacement, accumulator capacity and electrical load are summarized and the corresponding optimization suggestions are proposed, which realize the prediction and evaluation of RHES system performance under the excitation of different road profiles. Simulation suggests that this system can recover 100-400 W of power under road excitation. The findings of system analysis indicate that the component design can satisfy the damping characteristics and power performance required for specific application. The results also show that adjusting the electrical load and accumulator capacity is highly beneficial for controlling suspension behaviours, improving system reliability and increasing power regeneration.

Моделирование процесса вытеснения суспензии

Моделирование процесса вытеснения суспензии

Electric-Parameter-Based Inversion of Dynamometer Card Using Hybrid Modeling for Beam Pumping System

Conventional fault diagnosis and production calculation of an oil well can be conducted with the surface dynamometer cards, which are obtained by load sensor installed on the horse head. This method to measure the dynamometer cards is limited by the sensor maintenance and calibration, battery replacement, and safety hazards for staff. As the basic parameter of the oil extraction industry, electric parameters have the advantages of low cost and high efficiency. So the inversions of dynamometer card with electric parameters are attracting more and more attention. In order to solve the problem of insufficient data and consider the real-time performance in the actual oil extraction process, this paper proposes a novel hybrid model which consists of two parts: the mechanism model of polished rod load and the suspension displacement calculated with the space vector equations of motor and a data-dependent kernel online sequential extreme learning machine (DDKOS-ELM) model proposed to correct the output error of the mechanism model, which improves the kernel function selection and makes it real-time. Thus, the highlights of this paper can be summed up in two points: (1) under the circumstance of the bottom dead point detection without sensors, the mechanism modeling of the polished rod load and suspension displacement has been carried out from the perspective of mathematical model of AC motor; (2) a novel data-driven model based on data-dependent kernel online sequential extreme learning machine (DDKOS-ELM) has been proposed to improve the kernel functions selection. The coefficients in the data-dependent kernel function are optimized with improved free search algorithm (IFSA). The proposed hybrid model has been applied to a normal working oil well and the prediction results show better accuracy than the pure data-driven model and mechanism model.

The Control of an Active Seat Suspension Using an Optimised Fuzzy Logic Controller, Based on Preview Information from a Full Vehicle Model

The use of suspension preview information obtained from a quarter vehicle model (QvM) to control an active seat has been shown by the authors to be very promising, in terms of improved ride comfort. However, in reality, a road vehicle will be subjected to disturbances from all four wheels, and therefore the concept of preview enhanced control should be applied to a full vehicle model. In this paper, different preview scenarios are examined, in which suspension data is taken from all or limited axles. Accordingly, three control strategies are hypothesized—namely, front-left suspension (FLS), front axle (FA), and four wheel (4W). The former utilises suspension displacement and velocity preview information from the vehicle suspension nearest to the driver’s seat. The FA uses similar preview information, but from both the front-left and front-right suspensions. The 4W controller employs similar preview information from all of the vehicle suspensions. To cope with friction non-linearities, as well as constraints on the active actuator displacement and force capabilities, three optimal fuzzy logic controllers (FLCs) are developed. The structure of each FLC, including membership functions, scaling factors, and rule base, was sequentially optimised based on improving the seat effective amplitude transmissibility (SEAT) factor in the vertical direction, using the particle swarming optimisation (PSO) algorithm. These strategies were evaluated in simulation according to ISO 2631-1, using different road disturbances at a range of vehicle forward speeds. The results show that the proposed controllers are very effective in attenuating the vertical acceleration at the driver’s seat, when compared with a passive system. The controller that utilised suspension preview information from all four corners of the car provided the best seat isolation performance, independent of vehicle speed. Finally, to reduce the implementation cost of the “four suspension” controller, a practical alternative is developed that requires less measured preview information.

Model of suspension displacement in a porous medium

The displacement of monodisperse suspension by clean water in a porous medium, accompanied by the formation of deposit is considered. A flow of water is supplied at the inlet of the porous medium filled with suspension. The suspension is displaced by water moving at a constant velocity. A mathematical model of deep bed filtration of suspension in a porous medium based on size-exclusion mechanism of particle retention and pore clogging is formulated. It is proved that in the suspension area the solution depends only on time, and in the clean water area – only on the distance to the porous medium inlet. For constant initial conditions an exact solution of the problem is constructed. In the case of linear filtration coefficient, the analytic solution is given in explicit form. The properties of the obtained solutions are analyzed.

NARX ANN-based instrument fault detection in motorcycle

In the context of motorcycle, we can assist to an increasing interest toward semi-active suspension control systems able to improve both the comfort and the passenger’s safety in both racing and original equipment manufacturer applications. Such systems implement suitable strategies based on the measure of several quantities, among which the relative velocity of the wheels respect to the vehicle body with the aim of regulating in real-time the damping forces. The actual effectiveness of such strategy strongly depends on the reliability and accuracy of the data measured by the sensors involved in the control loop. Due to their simplicity and good performance in terms of linearity, the most used sensors for suspension displacement measurements are based on linear potentiometers but such kind of sensors suffer of wear and tear and aging higher than the other sensors involved in the control loop strategy. As a consequence, the fault detection of such sensor is strongly recommended to avoid wrong and in some cases dangerous suspension behaviors.To this aim, in this paper a Fault Detection scheme for the rear suspension stroke sensor is designed and verified. The residual generation is based on the use of a Nonlinear Auto-Regressive with eXogenous inputs (NARX) network which is able to effectively take into account for the system nonlinearity. Experimental results have proven the good promptness and reliability of the scheme in detecting different kind of faults as “un-calibration faults” (e.g. due to slight variations of the input/output sensor curve), “hold-faults” (e.g. due to the breaking of the potentiometer cursor), “open circuit” and “short circuit” (e.g. due to electrical interruptions and short circuits, respectively).In addition, to verify the feasibility of a real-time implementation on actual processing units employed in such context, the scheme has been successfully implemented on a microcontroller STM32 based on the general-purpose ARM-M4 architecture. The validation tests and analysis have shown that the proposed Instrument Fault Detection scheme could be successfully developed on these kind of architectures by assuring a real-time operating.

Optimization of damping in the passive automotive suspension system with using two quarter-car models

The paper presents the optimization of damping in the passive suspension system of a motor vehicle moving rectilinearly with a constant speed on a road with rough surface of random irregularities, described according to the ISO classification. Two quarter-car 2DoF models, linear and non-linear, were used; in the latter, nonlinearities of spring characteristics of the suspension system and pneumatic tyres, sliding friction in the suspension system, and wheel lift-off were taken into account. The smoothing properties of vehicle tyres were represented in both models. The calculations were carried out for three roads of different quality, with simulating four vehicle speeds. Statistical measures of vertical vehicle body vibrations and of changes in the vertical tyre/road contact force were used as the criteria of system optimization and model comparison. The design suspension displacement limit was also taken into account. The optimum suspension damping coefficient was determined and the impact of undesirable sliding friction in the suspension system on the calculation results was estimated. The results obtained make it possible to evaluate the impact of the structure and complexity of the model used on the results of the optimization.

THE IMPACT OF ROAD ROUGHNESS ON THE DURATION OF CONTACT BETWEEN A VEHICLE WHEEL AND ROAD SURFACE

The paper analyses the impact of the road micro-profile on the duration and the type of the vehicle wheel contact with the road surface driving at different speed. The selected vehicle bicycle model describes vertical displacements of front and rear wheels and their suspension as well as the impact of the vehicle body motion and longitudinal oscillation. International Roughness Index (IRI) and micro-profile irregularities of the road section analysed in the paper were identified using specialized road testing equipment. The experimental investigations measuring the vehicle suspension displacement and the body acceleration were carried out. Frequency characteristics of suspension motion and regularities of vertical movement of the wheel were identified after dividing the investigated road section according to driving modes. The analysis into the wheel contact with the road surface and identified correlations enable to determine the vehicle stability on selected quality roads.

Experiences with simulating on–road heavy vehicle suspension behaviour using servo–hydraulics

A research programme investigating simulation of the on–road behaviour of heavy vehicle suspensions using a two post servo–hydraulic facility for the purposes of assessing road–friendliness is outlined. The first series of tests on a full trailer with multi–leaf steel springs were encouraging and have previously been reported. These tests have now been repeated on the same vehicle fitted with air suspension. Although an excellent match between the suspension displacements measured during on–road tests and those obtained during the laboratory simulations was achieved, there was a significant difference between the wheel forces measured in the two types of test. It was hypothesised that this was probably due to this suspension having a proportionately greater auxiliary roll stiffness than the previous suspension. To investigate this hypothesis, additional trials were conducted. Modifications were made to the vehicle support structure of the actuators and further testing conducted. The results of these tests are presented.

Applied Technology in Road Identification Study of Off-Road Vehicle

To study the problem of the road identification of the off-road vehicle, a road identification method based on on-line monitoring of the vehicle running state was put forward. The time series data of the suspension displacement and the sprung mass were monitored. The spatial power spectrum density was calculated, aiming at automatically identifying the road roughness. The vehicle speed and the longitudinal vibration acceleration were collected, aiming at identifying the terrain slope. The state of the vehicle and engine was recorded. The rolling resistance coefficient was computed, based on the output torque of the engine. Comparing this coefficient with the threshold of the soft road surface, the soft road surface could be identified. On the basis of the identification result of the road feature, the vehicle running mode can be adjusted, improving the maneuverability of the off-road vehicle.

A Parametric Study on Performance of Semi-active Suspension System with Variable Damping Coefficient Limit

The research paper involves modeling of semi-active suspension system using quarter car model in Simulink environment. In order to modulate the damping coefficient value, fuzzy logic controller is modeled using Fuzzy Tool Box. Three different damping coefficient limits are selected for analyzing the response of system in terms of ride comfort. Road disturbance profile comprising a combination of two sinusoidal curves is modeled and the three semi-active suspension systems are simulated. Suspension displacement and velocity parameters are selected as the indicators of ride comfort. The results manifest supremacy of the system having damping coefficient limit of 4000N s/m. The optimized system performs well fulfilling the requirements of minimum percentage overshoot and rapid stabilizing time.

Optimization of Semi-active Suspension System Using Particle Swarm Optimization Algorithm

The paper involves modeling of quarter car models of passive and various semi-active suspension systems. Semi-active suspension is better than the passive and active suspensions based on optimum performance within the constraints of weight and operational cost. Fuzzy logic controllers are incorporated in the design scheme of semi-active models. Fuzzy logic based systems can handle non-linearities through heuristic rules. Particle swarm optimization technique is applied in order to determine the optimized scaling factors keeping the normalized ranges of inputs and output of fuzzy logic controller. The performance of resulting optimized system is compared with different systems based on various control algorithms (including passive system). The models are compared for attributes of road handling and ride comfort. The results clearly manifest supremacy of fuzzy logic based particle swarm optimized semi-active suspension system in relation to all other systems. The research presents an innovative approach of utilizing relative displacement and relative velocity as the input parameters resulting in no overshoot of the suspension displacement.

Finite Element Analysis of Mechanical Characteristics on the Composite Rubber Suspension of Heavy Vehicle

Taking the composite rubber suspension of a 6×4 heavy vehicle as research object, an accurate finite element model for the composite suspension at loading states is firstly built with consideration of nonlinear contact between spring leaves, and then a new finite element approach for calculating and analyzing static mechanical properties of the composite rubber suspension. Finally, the stress distribution and deformation is analyzed under different loads by using Hypermesh software and the results can be applied to its strength design. And moreover, some primary principles of the composite rubber suspension stiffness and displacement changing with different loads are obtained, which provides reference basis for virtual design and lightweight design of the vehicle composite rubber suspension.

Non-dimensionalised closed-form parametric analysis of semi-active vehicle suspensions using a quarter-car model

This article provides a non-dimensionalised closed-form analysis of semi-active vehicle suspensions, using a quarter-car model. The derivation of the closed-form solutions for three indices that can be used for ride comfort, vehicle handling, and stability are presented based on non-dimensionalised suspension parameters. The behaviour of semi-active vehicle suspensions is evaluated using skyhook, groundhook, and hybrid control policies, and compared with passive suspensions. The relationship between vibration isolation, suspension deflection, and road holding is studied, using three performance indices based on the mean square of the sprung mass acceleration, rattle space, and tyre deflection, respectively. The results of the study indicate that the hybrid control policy yields significantly better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for typical passenger cars. The results also indicate that for typical passenger cars, the hybrid control policy results in a better compromise between comfort, road holding and suspension travel requirements than both the skyhook and groundhook control methods.

Online Estimation of Vehicle Inertial Parameters for Improving Chassis Control Systems

AbstractVehicle chassis control systems aim at increasing vehicle safety and performance, while ensuring superior passenger comfort. Nearly all control algorithms are sensitive to the inertial parameters of a vehicle. As the vehicle mass, the moments of inertia, and the centre of gravity (COG) position can change significantly during operation, an accurate online estimation of these properties could substantially improve the performance of an active system. This paper presents an innovative algorithm for the online estimation of the inertial parameters of a road-vehicle. Using low-frequent suspension displacement signals and suspension stiffness characteristics, the vehicle mass and horizontal COG position are estimated. A Monte Carlo method determines the most probable mass distribution. Based on the assigned passenger weight, anthropometric data sets allow to calculate the inertial properties of every passenger, eventually resulting in the inertial parameters of the complete, loaded vehicle. The accuracy of the proposed algorithm is validated by means of a test campaign on an accurate kinematics and compliance testrig.

Estimating Road Angles With the Knowledge of the Vehicle Yaw Angle

This paper presents a method of estimating road angles using state observers and three types of sensors (lateral acceleration sensors, longitudinal velocity sensors, and suspension displacement sensors). The proposed method differs from those in most existing literature in three aspects. First, a “full-state” vehicle model is used to describe nonlinear vehicle dynamics on a sloped road. Second, “switching observer” techniques are used to suggest suitable sensors and to construct state observers. Lastly, the road angles are described by three Euler angles, and two of them are estimated simultaneously. The analysis indicates that (1) road angles affect vehicle dynamics through components of the gravitational force acting on the vehicle body. These gravitational forces can be correctly estimated with an estimation accuracy less than 7.5%, even when road angles vary with time. (2) Those road angles can be correctly estimated only when the vehicle yaw angle is known.

Assessment of different semi-active control strategies on the performance of off-road vehicle suspension systems

This paper deals with dynamics and control policies analysis of semi-active suspension systems for off-road vehicles. Three configurations of these vehicles; two-axle, three-axle and four-axle have been studied and their performances are compared. The application of several control policies of semi-active suspension system, namely skyhook; ground-hook and hybrid controls have been analysed and compared with passive systems. The results show that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement. The hybrid control policy is also shown to be a better compromise between comfort, road-holding and suspension displacement than the skyhook and ground-hook control policies. Skyhook control generally improves sprung mass responses while at the same time increasing unsprung mass responses. On the other hand, ground-hook control generally improves unsprung mass responses at the expense of the sprung mass responses. Results show an improvement in ride comfort and vehicle handling using four-axle over three-axle and two-axle when emphasis is placed on the response of the vehicle body acceleration, suspension and tyre deflection.

Vehicle Full-State Estimation and Prediction System Using State Observers

This paper presents a novel vehicle full-state estimation and prediction system that employs a ldquofull-state vehicle modelrdquo together with lateral acceleration, longitudinal velocity, and suspension displacement sensors to obtain the current and future vehicle state information. The full-state vehicle model is a vehicle model with 6 degrees of freedom (DOFs) and is described by 20-state nonlinear differential equations. The proposed approach differs from those in most of the existing literatures in three aspects. First, the road angles and the nonlinear suspension systems are incorporated into the vehicle modeling. Second, the ldquoswitching observer schemerdquo is introduced to significantly reduce the heavy work load that is required for the mathematical derivations. Finally, the full-state vehicle model is employed to predict the vehicle dynamics at future times. The simulation results show that the proposed system can accurately estimate and predict the state values. The relative accuracy of the state estimation is 2.66% on average and 2.86% on average of the state prediction. Furthermore, the proposed system can predict whether the vehicle rollover will occur when a vehicle performs a quick turn on a slope road.

Investigation of the interaction between a vehicle and the road using the second road excitation on the vehicle

A two-degrees-of-freedom quarter-vehicle suspension model is used in this work. The road is modelled as a Bernoulli—Euler beam with simply supported ends on a linear viscoelastic Kelvin foundation. Thus a two-dimensional vehicle—road system is built. Analytical solutions of the vehicle body, wheel, and road's dynamic response are derived by the mode superposition method. The solutions are directed to analyse the distribution of road displacement and the concept of second road excitation on the vehicle is proposed. Influences of the second road excitation on the vehicle suspension displacement, vehicle body acceleration, and tyre force are investigated. It is found that second road excitation should be considered in vehicle dynamic analysis when a heavy vehicle runs on a smooth highway road.