International Journal of Vehicle Design (9 papers in press)
Characteristics of HIC in prediction of mTBI relating to crash pulses
by Shahab Mansoor-Baghaei, Ali Sadegh
Abstract: The Head Injury Criterion (HIC) is a measure of traumatic head injury arising from an impact involving translational acceleration. The HIC equation is widely employed in automotive crashes to investigate the safety and protection of passengers due to impacts. In this paper, the HIC is analysed and investigated for its dependency on the shape of the head acceleration profiles. Specifically, using the MRI images of the human head, a 3-D FE model of the head was developed and was validated. The head model was subjected to a series of seemingly similar pulses, having equal HIC values and equal maximum accelerations, however having different corresponding times for their peak accelerations, i.e., advanced or retarded peaks. For each case, the model was analyzed, and the strain as an injury predictor in the brain was calculated. To confirm the FE results, a mathematical/analytical model of the brain viscoelastic material was developed and was subjected to different pulses. The results reflect that the strain in the brain for the two seemingly similar acceleration pulses have the same values of the HIC, even with the same two characteristics (maximum acceleration and impact duration time) being entirely different. Specifically, the pulses with the advanced peak time generated less strain in the brain when compared to that of retarded peak time. The results were also compared to the threshold of 10% to 15% strain in the brain that is commonly used as a predictor of the onset of an mTBI. Therefore, for retarded maximum acceleration pulses, it is recommended that more conservative HIC value threshold should be employed for head injury prediction.
Keywords: HIC; mild traumatic head injury; pulse shape; injury predictor; analytical approach.
Modelling and analysis of spring return electromagnetic valve actuator for SI engine
by Volkan Aygul, Murat Ayaz, Ahmet Necati Ozsezen
Abstract: In internal combustion engines, variable valve timing is one of the most important parameters that affects engine performance, fuel consumption and exhaust emission. In all engine speed values, electromechanical valve actuators (EVA) are needed for variable valve timing. EVAs allow the intake and the exhaust valves to be opened and closed at the right time by the camshaft. The valves can be opened and closed by the magnet circuits, and the opening and closing times can be controlled without depending on the camshaft present in all engines. The most critical part for EVA design is the solenoid in terms of the limited space on the cylinder head, the magnetic force required to open and close the valve, the coil temperature and the valve speed. This study proposes a comprehensive design of piston-type EVA and an analysis of its performance. The simulation results of the analysis with finite element method have been verified with the experimental test results. In addition, the conventional valve profile has been compared with the EVA valve profile.
Keywords: EVA; volumetric efficiency; finite element analysis; variable valve timing; SI engine; mechatronic system design.
Integrated control of active steering and braking systems with tyre forces and cornering stiffness estimation
by Qingwei Liu, Jiannan Luo
Abstract: A model-based integrated controller for active steering and active braking systems is proposed to enhance vehicle handling and stability. A hierarchical scheme is adopted, including vehicle layer based on Model Predictive Control (MPC), actuator layer, and observer layer. The MPC controller adopts a predictive model with the lateral force of front axle and yaw moment as inputs, which leaves the nonlinearity and coupling of tyre forces to be solved by the tyre force allocation algorithm in actuator layer, leading to more precise control action. In order to maintain satisfactory control performance with respect to the variation of tyre character, a Dual Extended Kalman Filter (DEKF) is designed in the observer layer to estimate tyre forces and cornering stiffness. The observed results are used to reduce the mismatch of the reference models in vehicle layer and actuator layer. The effectiveness of the proposed controller is demonstrated by simulations in the Carsim environment.
Keywords: integrated control; model predictive control; dual extended Kalman filter; tyre force estimation; tyre cornering stiffness identification.
Special Issue on: Multi-Objective Design and Structural Optimisation of Vehicle Components with Nature-Inspired Optimisation Algorithms
Determination of dynamic axle load using suspension deflection method for the load distribution optimisation of multi-axle vehicles
by Mustafa Umut Karaoğlan, Nusret Sefa Kuralay
Abstract: Identification of dynamic axle loads in multi-axle vehicles requires complex calculation methods because of the hyperstatic solving necessity. Existing methods for identification of axle loads are mostly based on response simulation by using a beam element to overcome the hyperstatic problem using numerical solutions. In this study, a suspension deflection method is proposed to determine the dynamic axle loads to optimisation of load distribution of a multi-axle vehicle having more than two axles. Load distribution optimisation for each axle is required for the definitions of maximum and minimum weights of the vehicle dynamically to provide better vehicle handling dynamics and axle strength. The determination of the dynamic axle loads is performed for a driving conditions with a climbing angle and a longitudinal acceleration to optimise the loads at the axles of the vehicle using a suspension deflection method. General equations and calculation methodology are presented for a multi-axle vehicle. Then, a numerical example is implemented using the suspension deflection method for a four-axle vehicle as a case study. The effect of the wheelbase, acceleration, climbing and characteristics of the suspension spring on load distribution are investigated for the optimisation of the loads on each axle of the vehicle. Finally, it is shown that the suspension deflection method is more simple and useful than other approaches to define the dynamic axle loads for an optimisation study of vehicles with multiple axles.
Keywords: axle load optimisation; suspension deflection method; multi-axle vehicles; load distribution.
Novel design concept for an automotive proving ground supporting multilevel CAV development
by Adam Nyerges, Zsolt Szalay, Zoltan Hamar
Abstract: Technological changes usually bring new possibilities in everyday life. Thanks to the recent evolution in science and technology, road transport is going to change radically. Today's complex assistant systems help the human driver to manoeuvre the vehicle safely. In the near future, connected and highly automated vehicles will also appear on the road, in multiple transport modes. Higher vehicle automation levels rely on disruptive technologies that simply cannot be tested and approved in the currently used sustaining technologies format. As validation processes become more complicated they require a more specific and ever-changing test environment. Current autonomous vehicle test environments are developed around activities that mostly concentrate on an urban test area, while every single element of the new Hungarian automotive proving ground is dedicated to the testing and validation of connected and automated vehicles. This paper will discuss this complex and integrated design concept, illustrating the unique points that differentiate the new Hungarian test facility from that of a conventional vehicle test track as well as from other current autonomous vehicle testing areas.
Keywords: connected and automated vehicles; autonomous driving; self-driving vehicles; testing and validation; test track; proving ground; smart city; intelligent transport.
Mine car suspension parameter optimisation based on improved particle swarm optimisation and approximation model
by Jun Zhang, Xin Li, Duyou Liu
Abstract: A suspension parameter optimization method is proposed in this paper to improve mine car ride comfort. The most influential parameters on vehicle ride comfort are chosen as optimisation variables by analysing parameter sensitivity using a 7-degrees-of-freedom vehicle model. A simplified regression model based on the response surface method accelerates the optimisation process. An improved chaos particle swarm optimisation (ICPSO) approach is proposed based on standard particle swarm optimisation to optimise suspension parameters in the regression model. The ideal match of suspension parameters is obtained. Simulation results show that improved suspension parameters can greatly ensure the weighted root mean square acceleration and tyre dynamic loads; additionally, suspension dynamic deflections are limited within an allowable range. Test results reveal that the suspension multi-parameter optimisation method based on ICPSO can improve vehicle ride comfort. Therefore, this method can be used to guide future research and development of suspension systems.
Keywords: mine car ride comfort; suspension parameter optimisation; Particle swarm optimisation; approximation model.
Design and evaluation of a passive inertial mass device for car suspension system
by Shuai Yang, Chuan Li
Abstract: A new adaptive nylon flywheel is proposed, which can achieve passive vibration control by generating variable equivalent mass. With changing rotational speed, the location of sliders in the slots changes, which leads to the creation of variable equivalent mass. Owing to the light weight and high strength of the nylon material, a higher changing ratio of equivalent mass can be achieved. To verify the performance of the adaptive nylon flywheel, the inverse screw system was applied. By using zero, impulse and sinusoidal input as road excitation, the proposed car suspension system is evaluated from riding comfort and tyre grip. Simulation results show the proposed suspension system provides better performance than traditional suspension system under most circumstances.
Keywords: inertial mass; passive; car suspension; adaptive flywheel.
Special Issue on: Recent Advances in Motion Control for Unmanned Marine Vehicles
Research on motion control of an autonomic launch and recovery device for unmanned surface vehicles
by Xiaomao Li, Xingang Jiang, Yang Yang, Yan Peng, Songyi Zhong, Huayan Pu, Shaorong Xie, Jun Luo
Abstract: In this study, a floating bracket device with visual inspection technology is developed for the autonomous launch and recovery of unmanned surface vehicles (USVs). To improve the success rate of docking between USVs and brackets in the recovery process, a reasonable controller is proposed to realise the position/posture regulation of the bracket. The state space equation is used to establish a system model, and the specific parameters are identified by using collected motion data. A sectional-type control framework is designed by model predictive control (MPC), which can satisfy the control requirements in different motion stages. The simulation results verify the accuracy of the identification model and the rationality of the MPC controller. The docking experiments demonstrated that the floating bracket with the proposed control system can be applied to launch and recovery missions of USVs.
Keywords: launch and recovery; unmanned surface vehicles; motion control; model predictive control; parameter identification.
Three-dimensional trajectory tracking control of underactuated autonomous underwater vehicles
by Zhenzhong Chu, Xuan Zhang, Daqi Zhu
Abstract: This study proposes a three-dimensional (3-D) trajectory-tracking control scheme for an underactuated autonomous underwater vehicle (AUV). Given the 3-D reference trajectory, the reference velocities, angles, angular velocities, forces, and torques were planned first. These reference variables were used to obtain the error dynamics. The backstepping technique was used to design the trajectory-tracking controller for tracking the AUVs reference trajectory. According to the Lyapunov stability theory, the trajectory-tracking system was stable and bounded, and the tracking errors converged close to a small neighbourhood of zero. Finally, the effectiveness of the developed control method was demonstrated using simulations.
Keywords: autonomous underwater vehicle; three-dimensional control scheme; trajectory tracking; backstepping.