Vehicle Handling Characteristics Research Articles

Structural and fatigue analysis of car wheel rims with carbon fibre composites

PurposeThe purpose of this study is to follow up on the structural and fatigue analysis of car wheel rims with carbon fibre composites in order to ensure the vehicular safety. The wheel is an essential element of the vehicle suspension system that supports the static and dynamic loads encountered during its motion. The rim provides a firm base to hold the tire and supports the wheel, and it is also one of the load-bearing elements in the entire automobile as the car's weight and occupants' weight act upon it. The wheel rim should be strong enough to withstand the load with such a background, ensuring vehicle safety, comfort and performance. The dimensions, shape, structure and material of the rim are crucial factors for studying vehicle handling characteristics that demand automobile designers' concern.Design/methodology/approachIn the present study, solid models of three different wheel rims, namely, R-1, R-2 and R-3, designed for three different cars, are modelled in SOLIDWORKS. Different carbon composite materials of polyetheretherketone (PEEK), namely, PEEK 90 HMF 40, PEEK 450 CA 30, PEEK 450 GL 40 and carbon fibre reinforced polymer-unidirectional (CFRP-UD) are used as rim materials for conducting the structural and fatigue analysis using ANSYS Workbench.FindingsThe results thus obtained in the analyses are used to identify the better carbon fibre composite material for the wheel rim such that it gives better structural properties and less fatigue. The R-3 model rim has shown better structural properties and less fatigue with PEEK 90 HMF 40 material.Originality/valueThe carbon composite materials used in this study have shown promissory results that can be used as an alternative for aluminium, steel and other regular materials.

Conventional Four-bar Linkage Steering System Adoption for Underslung Front Suspension

Recirculating ball (RCB) steering gear with four-bar linkage steering system is widely used in commercial vehicles with rigid front axle and over slung suspension owing to their architectural arrangement. The usage of RCB steering gear with four-bar linkage steering system with underslung suspension is not commercialized globally due to complexity of packaging suspension and steering linkages. Few automotive OEMs have studied and implemented Y link steering system in place of four-bar linkage steering system for underslung suspension arrangement. Y link steering system has got its inherent disadvantages such as higher bump steer, poor self-centering, complex linkages, more number of parts and less tire life. Further this arrangement is comparatively costlier than four-bar linkage steering system owing to their higher number of parts. In this paper, an extensive analysis has been made to implement the four-bar linkage steering system for underslung suspension vehicle. In this arrangement, the track rod (one of the links of a four-bar linkage system) is packaged above the leaf spring unlike in vehicles with overslung spring. Due to this unique arrangement, there exists some challenges in critical parameter optimization and packaging which are addressed in this paper. A mathematical model was developed to arrive at optimum steering and suspension geometry inorder to reduce the Ackerman error for better tire life and improve vehicle handling characteristics. By solving this mathematical model, optimum hardpoints can be arrived to achieve less Ackerman error, lower steering effort, lower bump steer, better steering returnability and best in class tire life. The present paper shows a possible approach to define the optimized steering and suspension linkages from the existing complex geometry with underslung suspension. This attempt is first of its kind in automotive industry and if commercialized successfully will go a long way in improving steering performance and cost savings for the vehicles with underslung suspension.

Design of a steering mechanism for the three-wheel tilting motorcycle

Abstract. There is a trend to develop three-wheel motorcycles because of their better stability and superior cornering ability compared to 1F1R (one front wheel and one rear wheel) motorcycles. The main purpose of this study is to establish a design process for the 2F1R (two front wheels and one rear wheel) three-wheel tilting mechanism and to reduce the turning radius to fulfill steering geometry in order to reduce the steering torque for a better handling feel. This research is divided into two parts: first, an existing steering tilting mechanism is selected as a design reference, and creative design methods are applied to set design constraints and requirements to facilitate a new mechanism design. A steering tilting mechanism is developed based on the design parameters of the steering mechanism and design objectives. Then Simpack software is employed to simulate handling tests on various routes and to verify the design model. The steering torque of the new mechanism is found to be much higher than that of the design reference. Therefore, the next step is to apply the Taguchi method to optimize the steering mechanism and to ensure that the parameter combination that satisfies the design objectives for the steering mechanism is selected. Finally, the route evaluation indexes are obtained from handling test simulations. From the results of the steering characteristics of the reference and research vehicle, the steering torque is found to be directly related to the response capability. Furthermore, the steering torque of the research vehicle is reduced by the optimization analysis using the Taguchi method, and the route evaluation indexes indicate that the vehicle's handling characteristics were improved.

Torque-Vectoring Control of Autonomous Vehicles Considering Optimization of Vehicle Handling Characteristics

Torque-Vectoring Control of Autonomous Vehicles Considering Optimization of Vehicle Handling Characteristics

A comparison of different models of passive seat suspensions

Long duration exposure to vehicle induced vibration causes various ailments to humans. Amongst the various components of the human-vehicle system, the seat suspension plays a major role in determining the level of vibration transferred to humans. However, optimising the suspension for maximising human comfort leads to poor vehicle handling characteristics. Thus, predicting human comfort through various seat suspension models is a widely researched topic. However, the appropriate seat suspension model to be used has not been identified so far. Neither has any prior work reported integrating models of all the components necessary for this analysis, namely human body, cushion, seat suspension and vehicle chassis, each with the appropriate level of complexity. This work uses a two-dimensional 12 DoF seated human body model with inclined backrest support, a nonlinear cushion model, a seat suspension model and a full vehicle model. Two kinds of road profiles – one with random roughness and one with a bump – have been used. It then compares the performance of five different seat suspension models based on a number of human comfort related parameters (seat to head transmissibility, suspension travel, seat acceleration, cushion contact force and head acceleration in both vertical and fore-aft directions) and vehicle handling parameters (vertical, rolling and pitching acceleration of chassis). The results clearly show the superiority of the configuration which involves a spring parallel to an inclined multi-stage damper. A separate analysis was also done to judge whether the integration of the vehicle model (with its associated complication) was necessary for this analysis. A comparison of the human body’s internal forces, moments, acceleration, and absorbed power with and without the vehicle model clearly indicates the need of using the former.

Developing a Strategy to Improve Handling Behaviors of a Medium-Size Electric Bus Using Active Anti-Roll Bar

Electric vehicles are a major trend in research and development in the automobile industry. A vehicle’s handling ability is changed when the structure of the power system is altered, which is more obvious in medium-sized buses with higher load and a longer body whose body stiffness is relatively less stiff. In this context, flexible multi-body dynamic modeling, instead of rigid body modeling, is used to reflect the stiffness effects of the vehicle body and chassis systems. A control strategy is developed with an active variable stiffness anti-roll bar to improve vehicle handling characteristics by using the flexible body dynamic simulation with consideration of the step and single sinusoidal steering input tests. Through simulation, it was learned that the proposed control strategy could reduce the time of stabilization by 54.08% and suppress undesired handling behaviors in the step steering input test. Moreover, at high speed, the original unsteady condition became stabilized with little sacrifice in yaw velocity. In the single sinusoidal steering input test, the time of stabilization could be reduced by 8.43% and with 14.6% less yaw angle changes in the improved design. The overall handling was improved.

Design and analysis of double wishbone suspension system

Suspension system serves purpose of providing stability to vehicle which results improving comfortability of riding. It provides traction control and steering stability. This paper proposes a method for designing double wishbone suspension system for electric solar vehicle with damper to lower wishbone. Recent trends in suspension system have focused on improving innovations in ride quality and handling of vehicles. It maintains a viable spectrum of economic growth by reducing costs and increasing efficiency simultaneously. Theoretical analysis is conducted using Lotus and Solid works to design double wishbone suspension system. The analysis is done for tadpole geometry car with double wishbone in front and swing arm in the rear wheels. Results in the paper are going to improve vehicle handling characteristics by controlling camber, toe angles and A-arm’s length. This is accomplished by changing the length of A-arm and the ground clearance and attach angle with the chassis by hit and trial method and improving possible traction and maneuverability. Results of the paper are presented in form of graph as a result of simulation conducted.

Rear-Wheel Steering Control for Enhanced Steady-State and Transient Vehicle Handling Characteristics

This paper presents a rear-wheel steering (RWS) control algorithm to enhance the vehicle handling performance without prior knowledge of tire characteristics. A RWS system is a chassis control module that can effectively improve vehicle maneuverability and stability. Since the tire-road friction coefficient is difficult to obtain in real world application, the proposed RWS control algorithm is designed so that it can be implemented without any tire-road information. The proposed RWS control algorithm consists of steady-state and transient control inputs. The steady-state control input is proportional to the driver's steering input for achieving the desired yaw rate gain. The desired yaw rate gain is obtained through an offline optimization that is aimed to minimize the vehicle lateral velocity. The transient control input consists of feedforward and feedback control inputs. The feedforward input is designed to improve transient responses of the yaw rate. Computer simulation studies have shown that a trade-off relationship between overshoot and response time exists when the RWS control input is a sum of the steady-state and feedforward inputs. To compromise this conflict, a feedback input has been designed. The overshoot can be significantly reduced while the response time is slightly changed via the feedback input. The proposed algorithm has been investigated via computer simulations. The simulation has been conducted for step steer and sine with dwell scenarios under various road friction conditions. The performance of a RWS vehicle was evaluated using objective indices. Simulation results show that the proposed algorithm enhances vehicle handling performance.

핸들링 설계 인자 개발을 위한 실차 환경 기반 차량 변수, 운전자 생체 신호 및 주관평가 상관성 연구

Vehicle handling characteristics change based on a variety of car design factors. Usually, the human driver is not considered in the vehicle handling design processes and rather, only vehicle design factors are considered in the design of handling characteristics. On the other hand, a professional driver performs a subjective evaluation of the car in a handling performance evaluation. Therefore, discrepancies are often found between the results of the handling characteristics designed based on the analysis and results felt subjectively by a human driver during actual driving. Therefore, it would be useful to develop a vehicle handling characteristics design method that considers both the vehicle and the human driver. This paper describes a real-car-based experimental platform that records the driver’s biological signs and vehicle movement signs and evaluates the handling performance. For a quantitative evaluation, the driver’s electrocardiogram, body pressure, brain wave, and movement signs and the vehicle movement signs were measured. For a qualitative evaluation, drivers wrote down their subjective feeling about car handling on the evaluation form. Data were obtained from two professional drivers participating in double lane change, step steer, and weave test. Based on the data, correlation analysis was conducted between the quantitative and qualitative indices. The drivers’ physiological signals were ranked by comparing with the vehicle signs based on the index sensitivity obtained in this study.

Gyroscopic stabilisers for powered two-wheeled vehicles

ABSTRACTThis paper illustrates the potential of a gyroscopic stabiliser for the stabilisation of single-track vehicles, at low and high speed as well as during braking. Alternative systems are considered, including single and twin counter-rotating gyroscopes, spinning and precessing with respect to different axes, either freely (passive stabilisers) or in a controlled way (active stabilisers). A suitable mathematical model has been developed and stability has been investigated both by eigenvalue calculation and time domain simulations. It has been found that the most effective configuration is one where the gyroscope(s) spin with respect to an axis parallel to the wheels' spin axis and swing with respect to the vehicle yaw axis. Passive systems may effectively stabilise both weave and wobble at medium and high speed, but cannot stabilise the vehicle at low and zero speed. On the contrary, actively controlled gyroscopes are capable of stabilising the vehicle in its whole range of operating speed, as well as during braking. The alteration of the original vehicle handling characteristics is negligible when active counter-rotating gyroscopes are used, and still acceptable if a single gyroscope is adopted instead.

Estimation of Road Loads and Vibration Transmissibility of Torsion Bar Suspension System in a Tracked Vehicle

Designing the suspension system of a tracked combat vehicle (CV) is really challenging as it has to satisfy conflicting requirements of good ride comfort, vehicle handling and stability characteristics. Many studies in this field have been reported in literature and it has been found that torsion bars satisfy the designer’s conflicting requirements of good ride and handling and thus have reserved a place for themselves as the most widely used suspension system for military track vehicles. Therefore, it is imperative to evaluate the effectiveness of the torsion bar under dynamic conditions of undulating terrain and validating the same by correlating it with computer simulation results. Thus in the present work, the dynamic simulation of a 2N + 4 degrees of freedom (DOF) mathematical model has been carried out using MATLAB Simulink and the vibration levels were also measured experimentally on a 12 wheel stationed high mobility military tracked infantry combat vehicle (ICV BMP-II) traversing different terrain, that is, Aberdeen proving ground (APG) and Sinusoidal, at a constant vehicle speed. The dynamic force transmitted to the hull CG through the 12 torsion bar suspension systems was computed to be around 26,700 N and found to match the measured values. The vibration isolation of the torsion bar in bounce was found to be effective, with a transmissibility from the road wheel to the hull of about 0.6.

Adaptive suspension strategy for a double wishbone suspension through camber and toe optimization

A suspension system is responsible for the safety of vehicle during its manoeuvre. It serves the dual purpose of providing stability to the vehicle while providing a comfortable ride quality to the occupants. Recent trends in suspension system have focused on improving comfort and handling of vehicles while keeping the cost, space and feasibility of manufacturing in the constraint. This paper proposes a method for improving handling characteristics of a vehicle by controlling camber and toe angle using variable length arms in an adaptive manner. In order to study the effect of dynamic characteristics of the suspension system, a simulation study has been done in this work. A quarter car physical model with double wishbone suspension geometry is modelled in SolidWorks. It is then imported and simulated using SimMechanics platform in MATLAB. The output characteristics of the passive system (without variable length arms) were validated on MSC ADAMS software. The adaptive system intends to improve vehicle handling characteristics by controlling the camber and toe angles. This is accomplished by two telescopic arms with an actuator which changes the camber and toe angle of the wheel dynamically to deliver best possible traction and manoeuvrability. Two PID controllers are employed to trigger the actuators based on the camber and toe angle from the sensors for reducing the error existing between the actual and desired value. The arms are driven by actuators in a closed loop feedback manner with help of a separate control system. Comparison between active and passive systems is carried out by analysing graphs of various parameters obtained from MATLAB simulation. From the results, it is observed that there is a reduction of 58% in the camber and 96% in toe gain. Hence, the system provides the scope of considerable adaptive strategy in controlling dynamic characteristics of the suspension system.

Effect of handling characteristics on minimum time cornering with torque vectoring

ABSTRACTIn this paper, the effect of both passive and actively-modified vehicle handling characteristics on minimum time manoeuvring for vehicles with 4-wheel torque vectoring (TV) capability is studied. First, a baseline optimal TV strategy is sought, independent of any causal control law. An optimal control problem (OCP) is initially formulated considering 4 independent wheel torque inputs, together with the steering angle rate, as the control variables. Using this formulation, the performance benefit using TV against an electric drive train with a fixed torque distribution, is demonstrated. The sensitivity of TV-controlled manoeuvre time to the passive understeer gradient of the vehicle is then studied. A second formulation of the OCP is introduced where a closed-loop TV controller is incorporated into the system dynamics of the OCP. This formulation allows the effect of actively modifying a vehicle's handling characteristic via TV on its minimum time cornering performance of the vehicle to be assessed. In particular, the effect of the target understeer gradient as the key tuning parameter of the literature-standard steady-state linear single-track model yaw rate reference is analysed.

Safety and Security of Cyber-Physical and Internet of Things Systems [Point of View

Computer system security and engineering system safety have traditionally been very distinct topics pursued by people with very different expertise. The advent of cyber-physical systems and the Internet-of-Things (IoT) changes that dynamic. Safety and security are now inextricably linked through our linkage of computer hardware and software with complex physical plants. Computers have been added to traditional engineering systems to achieve goals that we cannot achieve using traditional mechanical control. The automobile provides an important early example of the benefits of cyber-physical systems: computer engine control allowed manufacturers to simultaneously meet stiff requirements on both fuel economy and emissions; features such as antilock brakes and traction control improved vehicle handling and safety; and a new generation of supercars use software to not only provide sophisticated vehicle capabilities but also to change the vehicle's handling characteristics at the push of a button.

Detection and analysis of hazardous locations on roads: a case study of the Croatian motorway A1

The present paper describes research undertaken to identify causes underlying single-vehicle accidents (in terms of road design, driver behaviour and vehicle handling characteristics), which continuously happen in one specific section of Croatian motorway A1. The research resulted in a proposed procedure for a detection of hazardous locations on motorways and analysis of possible causes of single-vehicle accidents. The main part of the procedure involves test-rides with a vehicle equipped with devices (a ball bank indicator and a GPS data logger), which collect data on driver’s behaviour and vehicle handling characteristics (position, speed, longitudinal and lateral acceleration, heading, path radius, etc.). Despite the fact that the motorway was designed in accordance with the design guidelines, test rides performed by higher operating speeds identified two locations with a lateral acceleration change a few times higher than the design value. The collected data are then used for analysing hypotheses about the possible causes of accidents by using a vehicle dynamic model. The hypothesis that a sudden change in lateral acceleration could result in a driver’s inadequate manoeuvre like braking and cause a vehicle accident was analysed with a transient bicycle model. The results of test rides and the transient bicycle model indicate that speed, intensity of deceleration and underinflated tires significantly affect the probability of a single-vehicle accident.

Optimized Virtual Model Reference Control for Ride and Handling Performance-Oriented Semiactive Suspension Systems

This paper proposes an optimized virtual model reference (OVMR) control synthesis method for semiactive suspension control based on ride and vehicle handling characteristics. First, we present the semiactive Macpherson suspension system as an H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> robust output feedback-oriented control model. Then, by using the combination of a set of linear matrix inequalities (LMIs) and genetic algorithm (GA), the desired internal states for the tracking control problem of the semiactive suspension can be obtained via an OVMR. To achieve the H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> performance of ride comfort and vehicle handling against the influence of parameter uncertainties and external disturbances of the system, a robust adaptive controller is designed so that the controlled system can track the desired states generated from OVMR. The tracking control can be converted into a stabilization problem with asymptotic convergence in the sense of Lyapunov stability theorem. To validate the effectiveness of the proposed approach, the cosimulation technique is employed to bridge the gap between the mathematically well-defined system model and the optimization quality of control. It can be confirmed that the designed control system can achieve performance-effective suspension control through the confident software-in-the-loop (SITL) simulation.

A novel integrated chassis controller for full drive-by-wire vehicles

In this paper, a systematic design with multiple hierarchical layers is adopted in the integrated chassis controller for full drive-by-wire vehicles. A reference model and the optimal preview acceleration driver model are utilised in the driver control layer to describe and realise the driver's anticipation of the vehicle's handling characteristics, respectively. Both the sliding mode control and terminal sliding mode control techniques are employed in the vehicle motion control (MC) layer to determine the MC efforts such that better tracking performance can be attained. In the tyre force allocation layer, a polygonal simplification method is proposed to deal with the constraints of the tyre adhesive limits efficiently and effectively, whereby the load transfer due to both roll and pitch is also taken into account which directly affects the constraints. By calculating the motor torque and steering angle of each wheel in the executive layer, the total workload of four wheels is minimised during normal driving, whereas the MC efforts are maximised in extreme handling conditions. The proposed controller is validated through simulation to improve vehicle stability and handling performance in both open- and closed-loop manoeuvres.

Integrated control of active front steering and electric power steering system with EKF estimation of lateral force

Good vehicle handling characteristics are essential to ensure traffic safety. In the integrated system of electric power steering (EPS) and active front steering (AFS), the steering wheel torque may change abruptly with the interference of active steering. The additional front road wheel angle generated by AFS gives rise to the change of tyre lateral force, which results in the change of steering wheel torque finally. Although the tyre forces are difficult to measure, the extended Kalman filter (EKF) algorithm can be used to estimate it. The problem of steering wheel torque change can be resolved by tyre forces estimate based on the EKF observer in nonlinear system. The vehicle nonlinear mathematical model is presented and a nonlinear tyre lateral force estimator is also established basing on EKF. The estimated tyre lateral forces can be applied to compensate the abrupt change of steering wheel torque, which realises the combination of vehicle states estimation and vehicle control. The simulation results in MATLAB/Simulink show the effectiveness of proposed control strategy.

Suspension design by means of numerical sensitivity analysis and optimisation

The kinematic layout of suspension systems determines the wheel’s motion during bounce and rebound and thus, has a high influence on the dynamic performance of the vehicle. The presented study uses design of experiments (DoE) to determine dependencies between the location of the mounting points of the suspension devices and typical suspension indicators. Therefore, MBS models of a McPherson front as well as a multi-link rear suspension are considered. Then the locations of the mountings are varied by means of numerical optimisation by considering target values for chosen suspension indicators. While vehicle handling properties are usually anticipated by regarding suspension indicators, this paper aims to present a shortcut between the positioning of a suspension’s mounting points and the resulting consequences on the vehicle handling characteristics by means of DoE. Therefore, a virtual full vehicle model is introduced.

Multi-Wheeled Combat Vehicle Tire Modeling on Rigid and Soft Terrain

Multi-wheeled off-road vehicles performance depends not only on the total engine power but also on its distribution among the drive axles/wheels. In turn, this distribution is largely regulated by the drivetrain layout and its torque distribution which is constrained by the interaction between the wheels and the terrain (rigid or soft soil). In this paper three-dimensional, non-linear Finite Element Analysis (FEA) off-road tire models on rigid and soft terrain were developed using PAM-CRASH and the general trends of vertical load-deflection, cornering characteristics and aligning moment on rigid terrains are compared with published measured data of a similar tire for validation purposes. Non-linear tire look-up tables for rigid and soft terrain were developed based on FEA off-road tire simulation results and used for vehicle simulation using the multi-body dynamics code TruckSim. The predictions of vehicle handling characteristics and transient response during lane change test on rigid road at different vehicle speeds were compared with simulation results for same vehicle configuration using real experimental tire data. Simulation results are compared on the basis of vehicle steering, yaw rates and accelerations. The published US Army validation criteria has been used to validate simulation results.