Reliability-based robust design optimization of vehicle components, Part Ⅱ： Case studies

The reliability-based optimization, the relia- bility-based sensitivity analysis and robust design method are employed to propose an effective approach for reliability-based robust design optimization of vehicle components in Part I. Applications of the method are further discussed for reliability-based robust optimization of vehicle components in this paper. Examples of axles, torsion bar, coil and composite springs are illustrated for numerical investigations. Results have shown the proposed method is an efficient method for reliability-based robust design optimization of vehicle components.

Response surface methodology-based hybrid robust design optimization for complex product under mixed uncertainties

Minimizing the impact of the mixed uncertainties(i.e.,the aleatory uncertainty and the epistemic uncertainty) for a complex product of compliant mechanism(CPCM) quality improvement signifies a fascinating research topic to enhance the robustness.However, most of the existing works in the CPCM robust design optimization neglect the mixed uncertainties, which might result in an unstable design or even an infeasible design. To solve this issue, a response surface methodology-based hybrid robust design optimization(RSM-based HRDO) approach is proposed to improve the robustness of the quality characteristic for the CPCM via considering the mixed uncertainties in the robust design optimization. A bridge-type amplification mechanism is used to manifest the effectiveness of the proposed approach. The comparison results prove that the proposed approach can not only keep its superiority in the robustness, but also provide a robust scheme for optimizing the design parameters.

Reliability-based components, Part robust design optimization of vehicle I： Theory

The reliability-based design optimization, the reliability sensitivity analysis and robust design method are employed to present a practical and effective approach for reliability-based robust design optimization of vehicle components. A procedure for reliability-based robust design optimization of vehicle components is proposed. Application of the method is illustrated by reliability-based robust design optimization of axle and spring. Numerical results have shown that the proposed method can be trusted to perform reliability-based robust design optimization of vehicle components.

Multidiscipline collaborative optimization of differential steering system of electric vehicle with motorized wheels

Based on the multidiscipline design optimization theory, a multidiscipline collaborative optimization model of the differential steering system of electric vehicle with motorized wheels is built, with the steering economy as the main system and the steering road feel, the steering flexibility and the mechanic character of the steering sensors as the subsystems. Considering the coupled relationship of each discipline, the main system is optimized by the multi-island algorithm and the subsystems are optimized by the sequential quadratic programming algorithm. The simulation results show that the steering economy can be optimized by the collaborative optimization, and that the system can get good steering road feel, good steering flexibility and good mechanic character of the steering sensors.

Development of a deviation package method for low-cost robust optimization in compressor blade design

Manufacture variations can greatly increase the performance variability of compressor blades. Current robust design optimization methods have a critical role in reducing the adverse impact of the variations, but can be affected by errors if the assumptions of the deviation models and distribution parameters are inaccurate. A new approach for robust design optimization without the employment of the deviation models is proposed. The deviation package method and the interval estimation method are exploited in this new approach. Simultaneously, a stratified strategy is used to reduce the computational cost and assure the optimization accuracy. The test case employed for this study is a typical transonic compressor blade profile, which resembles most of the manufacture features of modern compressor blades. A set of 96 newly manufactured blades was measured using a coordinate measurement machine to obtain the manufacture variations and produce a deviation package. The optimization results show that the scatter of the aerodynamic performance for the optimal robust design is 20% less than the baseline value. By comparing the optimization results obtained from the deviation package method with those obtained from widely-used methods employing the deviation model, the efficiency and accuracy of the deviation package method are demonstrated. Finally, the physical mechanisms that control the robustness of different designs were further investigated, and some statistical laws of robust design were extracted.

Digital Design of Virtual Prototype based on Multidisciplinary Design Optimization

In order to obtain digital design of complex mechanical product as optimal as possible in an efficient way,multi- discipline integrated design method is proposed,which integrates multidisciplinary design optimization (MDO) into digital design process to design virtual prototype (VP) efficiently.Through combining MDO and multi-body system dynamics,MDO integra- tion platform,which takes VP as the core,is constructed.Then automated MDO design of VP is realized and changes of mechani- cal design project can be expressed intuitively during MDO design process.The proposed approach is also demonstrated by using inte- grated analyzing flow of vehicle engineering design.The result shows that the method not only can feasibly realize the MDO of VP, but also can solve the optimization problem of vehicle multi-body system dynamic performance.It can be adopted to the digital de- sign of other complex system.

Aircraft robust multidisciplinary design optimization methodology based on fuzzy preference function

This paper presents a Fuzzy Preference Function-based Robust Multidisciplinary Design Optimization(FPF-RMDO) methodology. This method is an effective approach to multidisciplinary systems, which can be used to designer experiences during the design optimization process by fuzzy preference functions. In this study, two optimizations are done for Predator MQ-1 Unmanned Aerial Vehicle(UAV):(A) deterministic optimization and(B) robust optimization. In both problems, minimization of takeoff weight and drag is considered as objective functions, which have been optimized using Non-dominated Sorting Genetic Algorithm(NSGA). In the robust design optimization, cruise altitude and velocity are considered as uncertainties that are modeled by the Monte Carlo Simulation(MCS) method. Aerodynamics, stability and control, mass properties, performance, and center of gravity are used for multidisciplinary analysis. Robust design optimization results show 46% and 42% robustness improvement for takeoff weight and cruise drag relative to optimal design respectively.

Locational Pricing of Uncertainty Based on Robust Optimization

With the increasing penetration of renewables,power systems have to operate with greater flexibility to address the uncertainties of renewable output.This paper develops an uncertainty locational marginal price(ULMP)mechanism to price these uncertainties.They are denoted as box deviation intervals as suggested by the market participants.The ULMP model solves a robust optimal power flow(OPF)problem to clear market bids,aiming to minimize the system cost as a prerequisite that the reserve margin can address all the relevant uncertainties.The ULMP can be obtained as a by-product of the optimization problem from the Lagrange multipliers.Under the ULMP mechanism,renewables and consumers with uncertainty will make extra payments,and the thermals and financial transmission right(FTR)holders will be compensated.It is further shown that the proposed mechanism has preferable properties,such as social efficiency,budget balance and individual rationality.Numerical tests are conducted on the modified IEEE 5-bus and 118-bus systems to demonstrate the merits and applicability of the proposed mechanism.

An incentive model between a contractor and multiple subcontractors in a green supply chain based on robust optimization

In this paper,we consider the incentive mechanism of a construction supply chain which includes a contractor and several subcontractors from both economic and environmental perspectives.Firstly,we describe the structure of the construction supply chain as well as the relationship between the contractor and subcontractors.Then,a bi-level nonlinear model with multiple followers comprising uncertain parameters is developed to balance the benefits of all supply chain members.In this model,the contractor is the leader while the subcontractors are followers.Next,we convert the primal model into a deterministic counterpart robust model,and a heuristic polynomial algorithm is designed to solve the transformed model.Finally,the validity of the model is verified by a numerical example.Our paper provides a method to quantitatively analyze construction projects from the perspective of supply chains while considering economic performance and environmental performance with the existence of uncertainty.

Design and optimization of an automatic hydraulic steer-by-wire system for an agricultural chassis

To meet the requirements of fast steering at low vehicle speed and slow steering at high vehicle speed,the automatic steering of agricultural chassis must control both the wheel steering angle and the steering angle’s angular speed.This study applied hydraulic steer-by-wire technology to the automatic steering control of agricultural chassis.First,the transmission mechanism of the designed steering system was optimized.According to the rule of least squares,aiming at the minimum sum of squares of errors between 10 ideal outer wheel angles and real outer wheel angles,the optimal solution of hole spacing on both sides of the steering hydraulic cylinder piston rod was 925 mm.The outer wheel angle error of the optimized steering mechanism throughout the steering stroke was less than 0.15°.Additionally,a hydraulic steer-by-wire system was developed,and the parameters of its critical components were calculated.Then,the compound control strategy of the steering cylinder piston rod displacement and moving speed was formulated for this automatic steering system.The entire control system included a valve control signal calculation model,an initial velocity calculation model,a correction velocity calculation model,and an attenuation velocity calculation model,and the formulae of each model were deduced.Based on the optimized parameters and the developed control strategy,a simulation model was built in AMESim,and simulation results showed that the proposed control strategy could achieve simultaneous controls of piston rod displacement and speed at different vehicle speeds and loads.The horizontal and vertical displacements of the right wheel center were plotted for typical vehicle speeds and steering commands.The results of this study provided a new idea for the application of hydraulic steer-by-wire technology in the automatic steering of agricultural chassis.

基于粒子群优化算法PID参数优化的双电机耦合驱动履带车辆转向控制

针对电驱动履带车辆转向灵敏度不高、控制精度难的问题进行转向控制策略研究,对双电机耦合驱动履带车辆开展动力学分析,利用数学仿真软件建立转向动力学模型。设计一种基于粒子群优化算法对比例-微分-积分控制器(Proportional-Integral-Differential controller,PID)参数优化的转向控制策略,以改进型时间乘绝对误差积分指标为粒子群优化算法目标函数,对PID转向控制策略中的控制参数进行实时优化,动态调节控制参数,实现车辆转向控制系统优化输出。利用硬件在环仿真平台和实车试验,对控制策略进行仿真和实车试验验证,试验结果验证了控制策略的有效性。

大转角快速反射镜柔性机构的优化设计与动态分析

针对压电驱动快速反射镜普遍存在的偏转范围小、扫描频率低等问题,本文设计了一种具有较大偏转角度的压电驱动快速反射镜柔性机构。首先开展了柔性机构嵌套级数、构型方式与固有频率、放大系数的相关性研究,得出了三级混合构型的初步设计方案。进一步将该机构离散为柔性铰链、刚性体和集中质量等基本单元,结合矩阵位移法,构建了柔性机构的通用动力刚度模型,得出柔性机构的结构参数与快速反射镜偏转角度的映射关系。在此基础上,对快速反射镜柔性机构关键尺寸参数进行优化设计,开展了柔性机构的模态分析。与国内外同类研究相比,该机构可以在保证较高一阶固有频率的基础上实现100 mrad机械偏转角度。

电液复合转向系统传感器安全机制设计

随着商用车自动驾驶技术的发展,对转向系统的主动转向功能的安全性愈加重视,电液复合转向系统是现阶段解决中重型商用车转向电动化和智能化的理想方案。文章提出了一种高安全性的双电机电液复合转向系统电气冗余架构,并从功能安全角度出发对最为关键的传感器安全机制进行设计,分别对转矩信号进行冗余校验和失效模式在线监控,对两个转角采集模块解析出转向盘以及电机位置传感器折算的绝对转角值进行正确性校验和多重容错判断,最后进行了硬件在环台架(HIL)测试,验证了所设计传感器安全机制的有效性。

车载资源约束下的控制器域网络异常检测自适应优化方法

针对在有限的车载资源约束条件下,如何兼顾控制器域网络(CAN)异常检测准确度和时效性的问题,该文提出一种CAN网络异常检测自适应优化方法。首先,基于信息熵建立了CAN网络异常检测的准确度和时效性量化指标,并将CAN网络异常检测建模为多目标优化问题;然后,设计了求解多目标优化问题的第二代非支配排序遗传算法(NSGA-II),将帕累托前沿作为CAN网络异常检测模型参数的优化调整空间,提出了满足不同场景需求的检测模型鲁棒控制机制。通过实验分析,深入剖析了优化参数对异常检测的影响,验证了所提方法能够在有限车载资源下适应多样化检测场景需求。

履带式工程车机械液压差速转向装置参数设计

机械液压差速转向装置作为一种双功率流转向装置,其参数设计是一个非线性、多目标和多参数优化问题。在对履带式工程车参数设计、目标评价和约束条件理论分析的基础上,提出了一种基于多岛遗传算法(Multi Island Genetic Algorithm, MIGA)和序列二次规划(Sequential Quadratic Programming, SQP)法的组合优化方法。根据组合优化的思想,对履带式工程车机械液压差速转向装置参数进行全局寻优,结合实例样车设计需要,将机械液压差速转向装置参数进行优化,优化后的参数可满足设计需要,表明所给出的组合优化方法可用于工程车机械液压差速转向装置参数设计。

重型卡车多连杆转向系统阿克曼转向误差优化

为了减少某重型卡车多连杆转向系统转角误差,确定转向机构的结构强度,建立了重型卡车多连杆转向系统多体动力学模型;首先利用模型进行了转向系统运动学分析,确定转向系统转角误差,采用试验设计方法,求解转向系统转向误差最小的机构;其次,进行转向系统动力学分析,得出转向系统杆件的最大受力,并应用有限元方法,优化转向系统的结构强度;结果表明,转向系统转向误差明显减小,提高了转向系统的可靠性;转向系统的性能达到某卡车设计要求。

某高空作业平台转向机构优化设计

针对某型号高空作业平台转向时存在的转向滑移、转向轮过度磨损等问题,在分析其转向机构几何关系的基础上建立转向机构数学模型,运用最小二乘法求解得出转向机构优化参数.根据相应参数建立原车及优化后的转向机构虚拟样机,并进行转向运动仿真分析.仿真结果表明,优化后的转向机构可使高空作业平台的转向更接近理想状态.

考虑间隙影响的汽车转向机构稳健优化设计

应用具有正态分布的设计参数与噪声因素的稳健设计理论,对汽车转向机构进行了稳健优化设计。以转向过程中转向机构14个位置的运动误差为目标函数,以主销中心距、轴距、转向梯形底角和转向梯形臂长度为设计变量,以各运动副间隙为噪声因素,以最小传动角及最大转角误差等为约束条件,建立了含间隙影响的转向机构稳健优化数学模型。设计结果表明,在运动副存在间隙或间隙变化时,此设计方法能有效保证转向机构的运动精度。

多轴转向车辆转向机构优化设计

多轴转向车辆转向机构是车辆转向时实现内、外轮理想转角关系的核心部件。该文根据汽车车轮转向特性,利用阿克曼定理,应用ADAM S软件建立多轴转向车辆转向机构的仿真模型,同时对转向机构进行了优化。和传统的设计方法相比,这种方法提高了精度和效率。对其它多轴车辆转向机构的优化设计也有一定的参考价值。

液压驱动装甲履带车辆转向特性仿真研究

为准确分析某液压驱动装甲履带车辆转向动态特性,在对液压驱动装甲履带车辆转向行驶理论分析的基础上,运用Matlab/Simulink软件平台建立系统转向仿真模型。对车辆在中等半径转向、小半径转向以及修正转向3种转向工况的动态响应特性进行仿真分析,得到了各种转向工况的车辆动态特性以及车辆在各种转向工况下允许的最高车速。仿真结果表明,车速的变化对转向系统压力影响显著。