International Journal of Vehicle Systems Modelling and Testing (8 papers in press)
An investigation of active safety control strategies for improving the lateral stability of car-trailer systems
by Lin Zhao, Yuping He
Abstract: This paper presents an evaluation of control strategies for improving the lateral stability of car-trailer systems. A linear stability analysis method is proposed for the evaluation. The strategies include active trailer differential braking, active trailer steering, and variable geometry approach. A linear three degrees of freedom (3-DOF) yaw-plane car-trailer model is generated for the controllers design, and a nonlinear 21-DOF yaw-roll car-trailer model is developed in CarSim to validate the stability control strategies by means of numerical simulations. To determine the stable motion boundary, eigenvalue analysis is conducted for identifying the vehicle critical speed. The linear quadratic regulator technique is applied to the design of controllers for active trailer braking, active trailer steering, and variable geometry strategies. It is revealed that the active trailer braking strategy is feasible and effective for improving the lateral stability of car-trailer systems. Simulation results demonstrate the effectiveness of the linear stability analysis method.
Keywords: car-trailer systems; active trailer braking; active trailer steering; variable geometry approach; linear quadric regulator; eigenvalue analysis; non-conservative forces; self-excited vibration; forced vibration.
Vehicle centre of mass, roll-centre and pitch-centre height estimation
by Theunis Botha, Schalk Els
Abstract: The location of a vehicles centre of mass is an important parameter as it has a determining effect on the dynamics of a vehicle. The height of the vehicle centre of mass from the roll and pitch centres have a large influence on the load transfer which occurs between wheels during braking and cornering manoeuvres. These vehicle parameters can vary significantly especially on off-road vehicles owing to the large differences in laden and un-laden weight. This paper proposes an algorithm where suspension forces and inertial parameters are estimated in real time using inexpensive sensor measurements and an unscented Kalman filter. The algorithm is experimentally validated on an off-road vehicle performing various manoeuvres and driving over different terrains. The real time estimation of these parameters could contribute significantly to improving vehicle safety and control.
Keywords: centre of gravity estimation; suspension force estimation; roll centre height.
Design of active yaw controller integrated with ABS and TCS for multi-wheeled vehicle
by Hossam Ragheb, Moustafa El-Gindy
Abstract: Prodigious improvements have been attained in active vehicle safety systems depending on different control systems. Active yaw control is one of these systems which targets the vehicle stability in case of any rapid and/or severe manoeuvre. This paper presents the design of an active yaw control system for an (8x8) multi-wheeled vehicle and its integration with other safety control systems, such as Anti-Lock Braking System (ABS) and Traction Control System (TCS). A simplified vehicle model 'bicycle model' is employed to predict the desired vehicle yaw behaviour depending on road condition and driving situation. A TruckSim MATLAB/Simulink vehicle model was developed to verify the proposed integrated safety control system. The developed integrated active yaw controller with ABS and TCS succeeded in improving vehicle directional stability and traction performance. Furthermore, it should be mentioned that the road friction affects the controller efficiency as it limits the available braking torque to be used by the controller.
Keywords: active yaw control; PID; ABS; TCS; TruckSim; MATLAB/Simulink; multi-wheeled vehicles.
Extended model for calculation of soil-wheel contact area parameters in rigid soil-deformable tyre approximation
by Elias Dias Rossi Lopes, André Flora Alves Pinto, Moisés Xavier Guimarães Valentim, Pedro Siciliano Peixoto, Ricardo Teixeira Da Costa Neto
Abstract: This article presents a new model for dynamic simulation of a rigid soil-deformable tyre approximation. Previous models are not ready to be implemented in computational simulations, for two main reasons: (1) they do not cover all possible operational regimes of a wheel, only slip values between 0 and 1, whereas the wheel can assume both values superior to 1 and negative values; and (2) most of them offer a bad approximation for calculation of contact parameters such as length, width and area of contact, with quadratic mean errors of over 100%. Therefore, this article extends the already-established Julien method for deformable soil to all slip values, and provides a new method for contact area calculation that reduces the quadratic mean error to the order of 10%, relative to empirical data. This is important for dynamic simulations of vehicles, as the deformable tyre-rigid soil method is applicable for almost all situations in the automotive regime; and applications are limitless, from estimating the influence of new parts adapted to an automobile, to using it to simulate the dynamics of a VR-model.
Keywords: vehicle dynamics; longitudinal dynamics; deformable tyres; tyre dynamics.
Experimental recording of unsteady temperatures in the piston of a high-speed diesel under transient conditions
by Andrii Avramenko, Fedor Abramchuk, Anatolii Kuzmenko
Abstract: Unsteady thermal loads on combustion chamber parts in a supercharged diesel engine dictate their service life. In practice, it is crucial to know the dynamic behaviour of temperatures and their gradients for automobile and tractor diesels that often change their operating conditions during running. Most reliable information can be obtained by experimental recording of temperatures on a test bench during engine tests. This information is used for mathematical modelling of temperature fields and temperature stresses. The objective of this research effort is the experimental recording of unsteady piston temperatures when the diesel load is increased and reduced rapidly. Thermocouples were chosen, and their thermal response was evaluated to increase the accuracy of recording piston temperatures. In addition, locations for installing thermocouples were chosen. A continuous-type current sensor was developed and refined to connect the hot junctions of the thermocouples with the recording instrumentation. The unsteady temperatures of the piston (aluminium alloy AL 25) in high-speed diesel 1FN 13/11,5 were recorded experimentally. Piston temperatures were recorded for cases when the load was increased and reduced rapidly. Treatment of experimental data has yielded the basic dynamic characteristics of the temperature fields in the diesel 1FN 13/11,5 piston).
Keywords: internal combustion engine; combustion chamber parts; unsteady temperatures; recording.
Economic optimisation of range-extended electric bus based on AMGA algorithm
by Yunfei Zha, Ronghui Guo, Fangwu Ma, Jinglong Song
Abstract: The power of a range-extended electric bus comes from its battery and range- extender. How to design the range-extender working point for the vehicle in the process of running is the key factor to achieve energy conservation and emission reduction. To solve this problem, a vehicle model was built by using AVL Cruise simulation software. Through Cruise and Isight co-simulation optimisation, a multi-objective optimisation model for per 100-km fuel consumption and pollutant emission is established. Optimal variables include upper and lower limits of the power unit and working point of the range-extender. Adaptive mutation genetic algorithm (AMGA) was used as an optimisation algorithm. Results showed that fuel consumption and pollutant emissions were effectively reduced. The per 100-km fuel consumption decreased by 48.0%, carbon monoxide emission decreased by 49.6%, hydrocarbon emission decreased by 47.28%, and nitrogen oxide emission decreased by 51.1%. The economics of range-extended electric bus have been greatly improved.
Keywords: range-extended electric bus; multi-objective optimisation; AMGA algorithm; optimal working point of range-extender.
Study on the laminated frame strength of heavy-duty fracturing pump truck considering slip effect
by Zhongyan Liu, Wensheng Xiao, Junguo Cui, Xiaodong Sun
Abstract: A differential equation for the slip effect of a continuous superposition beam under asymmetric loads and flexible support is formulated to study the effects of the stress distribution law and the slip effect of laminated frame under actual loads on the overall stress level of the frame. While considering continuity and free boundary conditions, a semi-analytical solution to the slippage of the superposed beam interface is proposed. An experiment for frame strength is designed based on the results of the numerical analysis. A field stress test is performed on the main frame and sub-frame, and the results demonstrate that the slip effect could influence the overall mechanical properties of the laminated frame to some extent. Considering the slip effect conforms to the actual mechanical properties of the laminated frame.
Keywords: fracturing pump truck; laminated frame; stress test; slip effect.
Development of a rolling truck tyre model using an automatic model regeneration algorithm
by Shahram Shokouhfar, Subhash Rakheja, Moustafa El-Gindy
Abstract: A three-dimensional finite element model of a rolling radial-ply truck tyre is developed to predict its vertical and cornering properties at relatively high speeds. The model includes a detailed representation of the tyre complex geometry and multi-layered composite structure including the carcass and belt plies, bead fillers and tread. LS-DYNA, a nonlinear finite element code, is used as the simulation tool. An algorithm is developed for efficient formulation of the model for parametric analyses. The validity of the proposed tyre model is demonstrated by comparing the predicted load-deflection, cornering and free vertical vibration characteristics with the reported experimental data. The simulation results revealed robust behaviour of the tyre model up to rolling speeds of 100 km/h. The verified tyre model is subsequently employed to study the influences of various operating parameters, namely, the inflation pressure, vertical load, rolling speed and road friction on the tyre vertical and cornering properties.
Keywords: rolling truck tyre models; multi-layered tyre structure; vertical tyre properties; cornering properties; parametric studies; finite element method; FEM; LS-DYNA; automatic model regeneration; truck tyres; tyre modelling; radial-ply tyres; carcass plies; belt plies; bead fillers; tyre tread; simulation; rolling speed; load deflection; free vertical vibration; tyre inflation pressure; vertical load; road friction; radial tyres.