基于智能算法的汽车气动外形参数多目标优化

为了对汽车外形进行优化设计,利用CFD软件与智能算法相结合的方法,以在天窗微开高速行驶状态下的汽车为优化的对象,选取气动阻力最小、气动升力为0、天窗后缘压强最小为`优化目标,以汽车关键外形参数为设计变量,对汽车气动外形进行多目标优化设计.同时,应用了数据挖掘技术评价设计变量与3个目标函数的影响关系,选取优化后的最佳关键参数制作汽车模型并进行风洞试验验证.研究结果表明:通过遗传算法优化的车身外形,在其他设计目标满足要求的条件下成功地将阻力系数降低了9.5%,并通过风洞试验验证了该智能算法结果的准确性.基于智能算法的汽车气动外形设计具有指导意义与实际应用价值,为汽车气动外形的多目标优化设计提供了一种高效、精确、可靠的先进优化方法.     

Research on Variable Structure and Adaptive Control for Strap-on Rocket

固体捆绑运载火箭变结构自适应控制

陈曦,刘玉玺,汪轶俊

（上海宇航系统工程研究所）

创新点说明：

对于新型固体捆绑火箭而言,由于箭体安装固体助推器,存在推力偏差较大、推力同步性较大的问题,导致火箭的结构干扰增大。安装尾翼外干扰增大,如经过大风区时,风干扰对箭体产生较大的影响。同时考虑建立动力学模型的过程中存在的参数不确定性、参数摄动、三通道间耦合的问题,传统的控制方法难以满足新型固体捆绑火箭的要求,因此本文率先将基于模型参考的变结构自适应控制方法应用于固体捆绑运载火箭上。

研究目的：

本文针对固体捆绑运载火箭控制系统的特点,应用变结构自适应控制理论,设计适用于固体捆绑运载火箭的控制系统,保障固体捆绑运载火箭的正常飞行。

研究方法：

（1）建立固体捆绑运载火箭动力学模型,考虑模型中参数不确定性、未建模动态及通道间耦合;

（2）分析固体捆绑运载火箭存在的干扰,例如：四个固体助推带来的推力偏差、推力不同步性、推力线偏斜,质心横移、芯级、发动机及尾翼安装误差、芯级发动机液体燃料晃动、箭体弹性振动等各类结构误差及风干扰等外干扰;

（3）针对固体捆绑运载火箭设计变结构自适应控制律的设计并证明其稳定性;

（4）Simulink仿真分析验证。

结果：

本文使用变结构自适应控制理论设计的控制系统可全局渐进稳定,三通道姿态角跟踪误差较小,姿态角收敛速度较快,系统性能良好,可有效处理各类结构干扰、外干扰、气动参数不确定性及未建模动态等问题,该控制系统的动态特性及控制品质良好,具有工程应用的前景。

结论：

本文将基于模型参考的变结构自适应控制方法应用于新型固体捆绑运载火箭的控制系统的设计中。给出了仅有俯仰方向有大姿态变动的条件下的火箭动力学偏量模型,并在此基础上设计变结构自适应控制律,同时证明了该控制系统的稳定性。本文通过理论及仿真分析,证明了变结构自适应控制理论在新型固体捆绑运载火箭上的应用可行性,具有一定的工程应用前景。

关键词：运载火箭;模型参考;变结构控制;自适应控制

     

通用型汽车胎压胎温监测系统研究

汽车轮胎压力监测系统(TPMS)是行车安全的关键,是汽车安全课题中的热点。基于无线胎压监测系统无需对现有车辆进行任何改造,安装调试方便快捷的需求,研究了基于无线传输的通用型汽车胎压胎温监测系统。设计了一种高灵敏度的无线传输方案,使得系统工作在ISM频段发射模块和接收模块相距35米时误包率低于1‰,且数据采集发射模块的温度压力测量精度不低于±2%FS,实现了远距离、高精度的无线传输。重点解决了卡车等大型车远距离无线数据有效传输问题,并提出了一种纯软件的轮胎定位方法,方便了系统的初装和更换。有效地防止轮胎爆胎,节省轮胎磨损,有良好的应用前景。     

Analysis on the gear-shifting schedule of hydraulic automatic transmission

With an advanced foreign hydraulic automatic transmission as the objective, an analytical method for the gear-shifting schedule is proposed. First the demanded maximum gradient of test is estimated. Then a test scheme and analytical procedure is formulated by initial test and hypothetical shift parameters. Finally through gear-shifting tests under different road conditions, load, accelerator pedal position limitation, throttle opening and output shaft speed are found to be the gear-shifting parameters. Under a common road condition, the gear-shifting schedule is a double-parameter schedule. Based on the driver''s demands on braking and dynamic performance, different shift schedules are made under downhill, uphill and quick releasing acceleration pedal conditions. The operation criteria of down-shift schedule on abrupt grade are proposed.     

Investigation on full vehicle height control algorithm using feedback linearization method

Aiming to improve the control accuracy of the vehicle height for the air suspension system, deeply analyzing the processes of variable mass gas thermodynamics and vehicle dynamics, a nonlinear height control model of the air suspension vehicle was built. To deal with the nonlinear characteristic existing in the lifting and lowering processes, the nonlinear model of vehicle height control was linearized by using a feedback linearization method. Then, based on the linear full vehicle model, the sliding model controller was designed to achieve the control variables. Finally, the nonlinear control algorithm in the original coordinates can be achieved by the inverse transformation of coordinates. To validate the accuracy and effectiveness of the sliding mode controller, the height control processes were simulated in Matlab, i.e., the lifting and lowering processes of the air suspension vehicle were taken when vehicle was in stationary and driving at a constant speed. The simulation results show that, compared to other controllers, the designed sliding model controller based on the feedback linearization can effectively solve the "overshoot" problem, existing in the height control process, and force the vehicle height to reach the desired value, so as to greatly improve the speed and accuracy of the height control process. Besides, the sliding mode controller can well regulate the roll and pitch motions of the vehicle body, thereby improving the vehicle''s ride comfort.     

Modeling and Simulation on the Underwater Trajectory of Non-Powered Vehicle Discharged from the Broadside

In order to study the underwater trajectory of the non-powered vehicle discharged from the broadside of the underwater platform, the simulation on the ascent process of non-powered vehicle was realized based on the mathematical model including the movement of the vehicle on the slope plate and in the seawater, the air chamber underwater working process etc. The simulation results show that the outlet speed and attitude of the vehicle meet the requirements of missile launching, the non-powered vehicle discharged from the broadside of the underwater platform is feasible. The simulation results with varying parameters show that the negative buoyancy of the vehicle imposes great impacts on the security of its discharge and the floating process, and the vehicle discharge depth is proportional to the floating time. The models and simulation result can be used in further research on the broadside discharging technology of the underwater platform.     

Design and implementation of path planning algorithm for vehicle parking

Parking is an important and indispensable skill for drivers. With rapid urban development, the automatic parking assistant system is one of the key components in future automobiles. Path planning is always essential for solving parking problems. In this paper, a path planning method is proposed for parking using straight lines and circular curves of different radius without collisions with obstacles. The parking process is divided into two steps in which the vehicle reaches the goal state through the intermediate state from the initial state. The intermediate state will be selected from the intermediate state set with a certain criterion in order to avoid obstacles. Similarly, an appropriate goal state will be selected based on the size of the parking lot. In addition, an automatic parking system is built, which effectively achieves the parking lot perception, path planning and performs parking processes in the environment with obstacles. The result of simulations and experiments demonstrates the feasibility and practicality of the proposed method and the automatic parking system.     

面向需求不确定的混装线物流车辆配送区域划分方法

静态的物流车辆调度方案难以适应需求不确定引起的混流装配线物料需求动态变化,导致配送效率低下,甚至生产流程紊乱等问题。针对此问题,提出了一种面向需求不确定的混流装配线物流车辆配送区域划分方法。首先,分析需求不确定对物流车辆配送量的影响,提出了基于信息熵的配送任务复杂性测度方法。其次,在复杂性测度的基础上,建立以物流配送车辆满载率最大、配送任务复杂度最小为目标的调度优化模型。最后,在实例中应用遗传算法对调度优化模型进行求解,得出物流车辆配送区域最优划分方案。结果表明,所提方法能够输出适应需求不确定的物流车辆配送区域划分方案,满足需求变化的同时,保证车辆满载率维持在最高水平,并降低配送任务复杂度,减少配送错误发生率。     

禁飞区无人机预警算法研究

针对大量在空中无秩序飞行的无人机有可能会闯入飞机场等禁飞区的情况,为了避免发生空中交通安全事故,提出了一种无人机禁飞区预警算法。首先,该算法经过坐标变换将描述无人机位置点的GPS坐标转换成对应的平面坐标;接着,采用改进的最小二乘曲线拟合算法预测出无人机的飞行轨迹;然后,通过计算预测的飞行轨迹曲线在当前点的切线是否会与描述禁飞区的电子围栏相交,来判断无人机是否会进入禁飞区。同时,所有的无人机都会安装上飞行数据记录模块,来实时地为该算法提供无人机的飞行状态信息。最后,通过MATLAB仿真实验验证了该预警算法的可行性和有效性,表明该算法可以对禁飞区周围的无人机进行预警。     

重力不同引起的载人月球车操纵差异分析

为分析月球与地球重力差异对驾驶员所带来的操纵影响,推导了载人月球车操纵动力学方程.基于径向基神经网络和间接逆模型的训练方法,建立以行驶轨迹为输入、驾驶员操纵转角为输出的载人月球车操纵动力学逆系统.采用两种不同类型的间接对比形式,包括地球重力条件下重复月面行驶的轨迹路线和月球重力条件下重复地面行驶的轨迹路线.将正弦函数和斜坡阶越函数作为驾驶员操纵输入,获得月球或地球重力条件下的行驶轨迹,并利用逆系统求解得到不同重力条件下行驶相同轨迹时驾驶员的操纵转角.结果表明,驾驶员在月球重力条件下需要做出更大的操纵转向角度、更快的操纵转向速度、更高的操纵转向变换频率,并且在月球重力条件下更不容易重复地球重力条件下的相同行驶轨迹.这说明载人月球车在月球重力条件下的操纵性能较差.