Structural Optimization for Roof Crush Test Using an Enforced Displacement Method

A roof crush test has been utilized to reduce passengers’ injuries from a vehicle rollover. The Federal Motor Vehicle Safety Standards (FMVSS) 216 and the Insurance Institute for Highway Safety (IIHS) perform actual vehicle tests and evaluate the vehicle’s ratings. Nonlinear dynamic response structural optimization can be employed not only for achievement of a high rating but also minimization of the weight. However, the technique needs a huge computation time and cost because many nonlinear dynamic response analyses are required in the time domain. A novel method is proposed for nonlinear dynamic response structural optimization regarding the roof crush test. The process of the proposed method repeats the analysis domain and the design domain until the convergence criteria are satisfied. In the analysis domain, the roof crush test is simulated using a high fidelity model of nonlinear dynamic finite element analysis. In the design domain, a low fidelity model of linear static response structural optimization is utilized with enforced displacements that come from the analysis domain. Correction factors are employed to compensate the differences between a nonlinear dynamic analysis response and a linear static analysis response with enforced displacement. A full-scale vehicle problem is optimized with a constraint on the rigid wall force from the analysis in the design domain.     

Modelling and model predictive control for a bicycle-rider system

This study proposes a bicycle-rider control model based on model predictive control (MPC). First, a bicycle-rider model with leaning motion of the rider’s upper body is developed. The initial simulation data of the bicycle rider are then used to identify the linear model of the system in state-space form for MPC design. Control characteristics of the proposed controller are assessed by simulating the roll-angle tracking control. In this riding task, the MPC uses steering and leaning torques as the control inputs to control the bicycle along a reference roll angle. The simulation results in different cases have demonstrated the applicability and performance of the MPC for bicycle-rider modelling.     

发展“绿色”汽车势在必行 但道路崎岖

在过去几年里,中国试图将新能源汽车开发领先于世界。但高成本、技术落后和低动力继续阻止了新能源汽车的量产。两年前,《纽约时报》曾刊登了一篇题为“中国力争成为世界电动汽车的领头羊”的文章,报道了中国汽车产业政策制订者将中国定位于“在未来三年内”成为全球领先的绿色能源汽车生产国之一。     

Validity and limitations of the kinematic roll center concept from the viewpoint of spatial kinematics using screw theory

In this research, the concept of the kinematic roll center is reviewed from the viewpoint of three-dimensional spatial kinematics. The theory of screws, which is widely used in spatial kinematics and robotics, is used to prove the validity of the conventional planar methods for finding the roll center in an initial symmetric vehicle position. The kinematic roll axis, which is referred to as the roll twist axis in this paper, is defined as the instantaneous screw axis of the vehicle body in roll motion with respect to the ground, and a three-dimensional method to determine the roll twist axis of a full-vehicle model in an initial symmetric position is introduced. The proposed method is based on screw theory, which relates the kinematics of a full-vehicle model to the statics of the full-vehicle model using the concepts of screws, twists, wrenches, the rate of working, and the reciprocity of screws. The results of the proposed three-dimensional method are compared with those of the conventional planar methods, and it is found that the conventional methods are valid under the assumption that the vehicle is in a symmetric situation.     

Design and evaluation of sideslip angle observer for vehicle stability control

This paper presents a method for estimating the vehicle side slip angle, which is considered as a significant signal in determining the vehicle stability region in vehicle stability control systems. The proposed method combines the model-based method and kinematics-based method. Side forces of the front and rear axles are provided as a weighted sum of directly calculated values from a lateral acceleration sensor and a yaw rate sensor and from a tire model according to the nonlinear factor, which is defined to identify the degree of nonlinearity of the vehicle state. Then, the side forces are fed to the extended Kalman filter, which is designed based on the single-track vehicle model associated with a tire model. The cornering stiffness identifier is introduced to compensate for tire force nonlinearities. A fuzzy-logic procedure is implemented to determine the nonlinear factor from the input variables: yaw rate deviation from the reference value and lateral acceleration. The proposed observer is compared with a model-based method and kinematics-based method. An 8 DOF vehicle model and Dugoff tire model are employed to simulate the vehicle state in MATLAB/SIMULINK. The simulation results shows that the proposed method is more accurate than the model-based method and kinematics-based method when the vehicle is subjected to severe maneuvers under different road conditions.     

Requirement-based testing of an automotive ECU considering the behavior of the vehicle

HILS (Hardware In the Loop Simulation) and RBT (Requirement-Based Testing) are widely used to evaluate the performance and reliability of automotive ECUs (Electronic Control Units). The HILS method is used to predict the behavior of ECU-installed vehicles and to evaluate the performance of ECU controllers. RBT evaluates whether the embedded system satisfies the pre-defined requirements. In this study, the behavior of a vehicle is regarded as a system requirement, and an embedded system test procedure that evaluates the system requirement is proposed. In particular, a new method is introduced, which integrates HILS with RBT. Using the proposed method, the behavior of an articulated vehicle equipped with an AWS (All Wheel Steering) ECU is evaluated with RBT software.     

Torque control of engine clutch to improve the driving quality of hybrid electric vehicles

As a powertrain for hybrid electric vehicles (HEVs), the automatic transmission (AT) is not only convenient for the driver but also reduces hybridization costs because the existing production line is used to produce the AT. However, it has low fuel economy due to the torque converter. To overcome this disadvantage, this paper studies HEVs equipped an AT without a torque converter. In this case, additional torque control is needed to prevent the driving quality from deteriorating. This paper suggests three different torque control methods and develops a simulator for an HEV that can simulate the dynamic behaviors of the HEV when the engine clutch is engaged. The HEV drive train is modeled with AMESim, and a controller model is developed with MATLAB/Simulink. A co-simulation environment is established. By using the developed HEV simulator, simulations are conducted to analyze the dynamic behaviors of the HEV according to the control methods.     

Model development and experimental research on an air spring with auxiliary reservoir

This paper focuses on the dynamic stiffness and overall equivalent damping of an air spring connected to an orifice and an auxiliary reservoir, with respect to the displacement excitation frequency, orifice area, and auxiliary reservoir volume. A theoretical model of this air spring with its auxiliary reservoir is derived by utilizing the energy conservation equation, gas state equation, and orifice flow rate equation. Simulation results from the presented model reveal that, when the air spring is subject to harmonic displacement excitation, its dynamic stiffness increases with an increase in excitation frequency and decrease in orifice area. Smaller orifice areas and lower excitation frequencies result in higher overall equivalent damping. A validation experiment is also implemented. When compared with experimental results, simulations show consistent varying trends of the dynamic stiffness and overall equivalent damping. The model developed here can correctly describe the behavior of the air spring with auxiliary reservoir, indicating that it is reasonable and feasible.     

Reducing the memory footprint of OSEK-based systems via stack sharing and light-weight ready queues

OSEK OS (Offene Systeme und deren Schnittstellen für die Elektronik in Kraftfahrzeugen Operating System) is an open, real-time operating system standard for ECU software in vehicles. Because it was originally designed to be used in an extremely resource-constrained environment, an OSEK-compliant operating system must incur low processing overhead and memory usage. Unfortunately, as OSEK OS has evolved over time, it now specifies nontrivial kernel features along with multiple conformance classes and application modes. This may lead to unwanted dynamic resource usage in a system using OSEK OS unless the standard is carefully interpreted and designed into an OSEK OS implementation. In this paper, we analyzed the various kernel features of OSEK OS and their interactions to identify areas in the standard that warrant further resource usage optimization. In particular, we attempted to reduce the run-time memory footprint. Based on our analyses, we present two kernel mechanisms: (1) stack sharing among tasks and (2) light-weight ready queue handling specialized for OSEK OS conformance classes. We also offer implementation methods for the proposed mechanisms by extending OIL and associated tools. Finally, we show the effectiveness of the proposed mechanisms via extensive experiments. Our mechanisms allow OSEK-based systems to use only 36% of the memory requirements of conventional OSEK-based systems on average.     

英国与荷兰非机动化交通模式比较研究

非机动化交通模式以其低能耗、健康、低消费、缓解交通拥堵等优势被认为是生态化且可持续化的绿色交通发展模式。近些年来,英国政府与荷兰政府提出了一系列的政策措施,加强了对交通安全的教育,用于降低机动化交通速度,促进非机动化交通模式的发展。通过对比发现非机动化交通配套设施在英国的发展远不及荷兰完善,且荷兰的非机动化交通与其他模...