Optimizing Flight Trajectories for Space Vehicles with an Additional Fuel Tank. II

We solve the optimization problem for space trajectories of spacecraft flights with an auxiliary fuel tank from a low round orbit of a man-made Earth satellite to a geotransitional orbit. Control over the spacecraft motion is performed with a jet engine of bounded thrust. To discard the auxiliary tank, one has to turn off the engine, which takes some known time. The mass of the discarded tank is assumed to be proportional to the mass of fuel spent, and the mass of the engine and additional constructions is proportional to the thrust-to-weight ratio. We minimize the value of injection impulse needed to transfer to the geostationary orbit for a given useful mass.In the second part of the paper the problem at hand is formalized as an optimal control problem for a collection of dynamical systems and is solved based on the corresponding maximum principle. In this work we solve boundary problems of the maximum principle numerically with the shooting method. As a result of solving the problem, we construct one- and two-revolution Pontryagin extremals. We perform a series of parametric computations that are used to determine optimal parameters of the spacecraft construction: the best thrust-to-weight ratio and the best distribution of fuel among the tanks.     

Optimization of interorbital three-dimensional transfer trajectories for stage spacecraft

Problems of three-dimensional trajectory optimization of transfers for stage spacecraft and spacecraft with auxiliary fuel tank (AFT) from the low circuit orbit of the Earth’s artificial satellite (EAS) into the geostationary orbit and optimization problems of fuel distribution in stages or tanks are solved. Control of spacecraft motion is conducted by jet engines of bounded thrust; stage engines can have different characteristics, i.e., thrust-to-weight ratio and specific thrust. The used stage or auxiliary fuel tank is detached on the passive segment. Detachment is considered to be instantaneous, if the spacecraft position and velocity do not change at the detachment instant and the mass decreases in jumping mode. The mass of detached tanks is considered proportionate to the mass of consumed fuel; the mass of engine and auxiliary constructions, to thrust-to-weight ratio. The useful mass of the spacecraft with the limited time of transfer is maximized. The considered problems are intricate nonlinear optimal control problems with discontinuous phase variables. They are formalized as optimal control problems by a union of dynamic systems and are solved on the basis of the corresponding principle of the maximum. In this paper, boundary-value problems of the principle of the maximum are numerically solved by the shooting method. The choice of computing schemes of the shooting method and solution to systems of nonlinear equations is conducted by using a series of auxiliary problems.     

Finding analytic solutions on active arcs of the optimal trajectory in a gravitational field and their applications

We consider a method for finding partial solutions for the optimal motion problem of a space vehicle in a central Newtonian field on intermediate thrust arcs. This is the Lehmann-Filhés method based on knowing an incomplete integral of the Hamilton–Jacobi equations. With this method, we obtain a number of partial solutions that can be applied to solving practical problems of space flight mechanics. As an example, we solve the problem of rotating the axis of an elliptical orbit. We compare characteristic velocities necessary to rotate the axis of an elliptical orbit.     

Control problems in contingency during flight of a space vehicle with low thrust engine

An approximate method of online analysis of contingency during the flight of a space vehicle with low thrust engine and nuclear power unit to asteroids is proposed. The properties of dependence of the vehicle mass near the target on the flight characteristics and parameters of the space vehicle are used. Examples of the choice of a new variant of the expedition to several asteroids of the Main belt in the case of a contingent change in the power of the energy unit are given.     

无人飞行器纵向剖面轨迹优化

对飞行管理系统的纵向剖面轨迹优化功能进行了研究.以固定距离最省油为优化指标,用能量法动态地建立了3阶段轨迹优化模型.区别于固定推力只对速度寻优的传统的模型求解方法,把发动机推力和速度同时作为寻优变量,并结合无人飞行器飞行的物理过程,将3阶段轨迹优化模型进一步变换成非线性规划问题,利用再开始FR(Fletcher-Revees)共轭梯度法进行求解.最后以某型无人飞行器为例进行仿真验证,结果表明将发动机推力设为变量比推力固定求得的纵向剖面最优轨迹更省油,对节省燃油降低经济成本有一定的实用参考价值.     

Optimization of fuel consumption and NOx emission for mild HEV via hierarchical model predictive control

In this paper, we consider the fuel economy optimization problem for a mild hybrid electric vehicle (HEV) using hierarchical model predictive control. In the proposed algorithm, two problems are addressed: eco-driving and torque distribution. In the eco-driving problem, vehicle speed was controlled. Considering the reduction in fuel consumption and NOx emissions, the torque required to follow the target speed was calculated. Subsequently, in the torque distribution problem, the distribution between the engine and motor torques were calculated. In this phase, engine characteristics were considered. These problems differ in terms of time scales; therefore, a hierarchical model predictive control is proposed. Lastly, the numerical simulation results demonstrated the efficacy of this research.     

Torque control strategy with V2X information for HEVs tominimize fuel consumption

Today, much information from traffic infrastructures and sensors of ego vehicle is available. Using such information has a potential for internal combustion engine vehicle to reduce fuel consumption in real world. In this paper, a powertrain controller for a hybrid electric vehicle aiming to reduce fuel consumption is introduced, which uses information from traffic signals, the global positioning system and sensors, and the preceding vehicle. This study was carried out as a benchmark problem of engine and powertrain control simulation and modeling 2021 (E-COSM 2021). The developed controller firstly decides reference acceleration of the ego vehicle using the traffic signal and the position information and the preceding vehicle speed. The acceleration and deceleration leading to increase in unnecessary fuel consumption is avoided. Next, the reference engine, generator, and motor torques are decided to achieve the reference acceleration and minimize fuel consumption. In addition, the reference engine, generator and motor torques were decided by the given fuel consumption map for the engine, and by the virtual fuel consumption maps for the generator and the motor. The virtual fuel consumption is derived from the efficiency maps of the generator and the motor using a given equivalent factor, which converts electricity consumption to fuel for the generator and the motor. In this study, a controller was designed through the benchmark problem of E-COSM 2021 for minimizing total fuel consumption of the engine, the generator, and the motor. The developed controller was evaluated in driving simulations. The result shows that operating the powertrain in efficient area is a key factor in reducing total fuel consumption.     

Optimal trajectories for hypersonic launch vehicles

In this paper, we derive a near-optimal guidance law for the ascent trajectory from earth surface to earth orbit of a hypersonic, dual-mode propulsion, lifting vehicle. Of interest are both the optimal flight path and the optimal operation of the propulsion system. The guidance law is developed from the energy-state approximation of the equations of motion. Because liquid hydrogen fueled hypersonic aircraft are volume sensitive, as well as weight sensitive, the cost functional is a weighted sum of fuel mass and volume; the weighting factor is chosen to minimize gross take-off weight for a given payload mass and volume in orbit.     

基于能量的天基拦截轨道设计与优化

在空间作战轨道拦截问题中,研究了天基拦截器的最小能量拦截轨道优化问题。针对拦截器远距离单脉冲拦截消耗燃料过多的问题,在以往的单脉冲最小能量拦截轨道基础上继续减小了拦截器燃料的消耗。首先运用全局搜索法,以某个在轨卫星为天基平台,在某个时间段内,快速搜索出单脉冲最小能量拦截轨道;再以单脉冲最小能量拦截轨道为基础,建立多脉冲拦截轨道的数学模型,以拦截器需要消耗的总燃料最少为目标,利用非线性规划方法对此单脉冲最小能量拦截轨道进行进一步的多脉冲优化。仿真结果表明,单脉冲最小能量拦截轨道经过多脉冲优化后,拦截器需要的总速度增量减小了,即达到了减轻拦截器燃料负担的目的。     

质量矩/直接力复合控制飞行器的姿态控制

研究了大气层内质量矩/直接力复合摔制飞行器的姿态控制问题.建立了质量矩/直接力复合控制飞行器六自由度数学模型,分析了质量矩控制和直接力控制的控制机理,基于质量矩控制与直接力控制的各自优势,提出了质量矩与直接力复合控制乜行器的姿态复合控制策略,确定了在不同条件下的具体控制方式.应用变结构理论设计了飞行器的姿态控制规律,分别给出了滑块期望位簧和发动机期望开关信息的求法,在复合控制策略的指导下,给出控制指令.仿真结果表明,方法能够在保证系统稳定的情况下有效实现飞行器的姿态控制.     

Autonomous longitudinal motion of a paraglider. Mathematical simulation, synthesis of control

Mathematical model of motion of a paraglider in the longitudinal plane is constructed. The vehicle consists of a sail and a gondola. Both bodies are assumed to be perfectly rigid. They are connected by slings which are assumed to be perfectly rigid rods. Thus, the considered model of the paraglider represents one rigid body with three degrees of freedom. An engine, which develops thrust using a propeller, is mounted rigidly on the gondola of the vehicle. The orientation of the thrust vector with respect to the gondola is constant. The steady-state regimes of motion of the paraglider for the constant thrust are found. The law of automatic thrust control for which the flight of the vehicle is stabilized at the given altitude is designed. The domains of asymptotic stability of the paraglider motion at a constant altitude, including with account of delay, are constructed in the plane of the feedback coefficients. In this plane the domains in which a given stability factor is ensured are constructed. Some results of numerical simulation of the flight of the vehicle are presented.     

Robust control design of an air‐breathing engine for a supersonic vehicle using backstepping and UKF

This paper presents an efficient robust control design approach for an air‐breathing engine for a supersonic vehicle using the Lyapunov stability theory based nonlinear backstepping control, augmented with unscented Kalman filter (UKF). The primary objective of the control design is to ensure that the thrust produced by the engine tracks the commanded thrust by regulating the fuel flow to the combustion chamber. Moreover, as the engine operates in a supersonic range, an important secondary objective is to manage the shock wave location in the intake for maximum pressure recovery with adequate safety margin by varying the throat area of the nozzle simultaneously. To estimate the states and parameters as well as to filter out the process and sensor noises, a UKF has been incorporated for robust output feedback control computation. Furthermore, independent control designs for the actuators have been carried out to assure satisfactory performance of the engine. Additionally, a guidance loop is designed to generate a typical flight trajectory of the representative vehicle using a nonlinear suboptimal input constrained model predictive static programming formulation for testing the performance of the engine. Simulation results clearly indicate quite successful robust performance of the engine during both climb and cruise phases.     

利用高斯型方程进行卫星轨道机动仿真

在分析飞行器在连续力作用下的运动时,目前常用Hill模型,但Hill模型仅适用于短距离内短时间内飞行器机动问题.高斯(Gauss)模型作为一个研究绕动力作用下飞行器轨道变化的有效分析工具,可用于有限推力长时间作用下的轨道变化分析.从Gauss模型的基本形式推导出Gauss模璎的无奇点方程,并从理论角度和仿真计算方面分析了外力的大小、方向对轨道机动结果的影响以及轨道的偏心率、平近点角对轨道机动的影响.结果证明采用数值方法可以有效解决Gauss模型求解困难的问题,Gauss型模型用于轨道机动分析具有很好的普适性.     

基于CVT的混合动力汽车建模与仿真

建立了基于无级变速器 (Continously Variable Transmission,CVT) 的前向并联式混合动力电动汽车动力系统模型,为了研究整车动力性、经济性,根据行驶动力学方程,采用极值原理和曲面拟合法对发动机台架试验得到的数据进行了多项式拟合,建立了发动机万有特性与最佳操作曲线(Optimal Operating Line,OOL) 模型,并建立了牵引用三相感应电机动力模型以及牵引蓄电池(State of Charge,SOC)模型.同时,提出了燃油消耗最低、蓄电池充放电平衡的能量分配控制策略,进行整车动力性仿真计算,仿真结果表明在保证循环结束电池充放电基本平衡的同时发动机燃油消耗最低,仿真试验对比结果验证了建立的模型的精确性.     

Nonlinear dynamics and control of space vehicles with multiple fuel slosh modes

This paper studies the modeling and control problem for planar maneuvering of space vehicles with fuel slosh dynamics. A multi-mass–spring model is considered for the characterization of the most prominent sloshing modes. The control inputs are defined by the gimbal deflection angle of a non-throttable thrust engine and a pitching moment about the center of mass of the spacecraft. The control objective, as is typical in a thrust vector control design for a liquid upper stage spacecraft during orbital maneuvers, is to control the translational velocity vector and the attitude of the spacecraft, while attenuating the sloshing modes characterizing the internal dynamics. Subsequently, a nonlinear mathematical model that reflects these specifications is derived. Finally, Lyapunov-based nonlinear feedback control laws are designed to achieve the control objective. A simulation example is included to illustrate the effectiveness of the control laws.     

电动汽车增程器燃油效率优化控制

针对如何提高增程器燃油效率,降低整车油耗的问题,提出了一种基于PRP共轭梯度法的增程器燃油效率优化控制方法.首先,以产生给定能量燃油效率最高为优化性能指标,以发动机转矩和发电机转矩为寻优变量,建立了增程器燃油效率优化控制问题的离散系统模型.然后,对算法实现过程中发动机、发电机的最高转速和最大转矩限制的处理方法进行了阐述,给出了基于PRP共轭梯度法的增程器燃油效率优化控制问题的数值实现方法的详细步骤.最后,仿真和实验结果表明本文提出的优化控制方法可以有效提高增程器的燃油效率.     

飞机燃油箱无油空间氧气浓度测量系统研究和发展综述

为了降低飞机燃油箱可燃性,绝大部分民用和军用飞机都安装了油箱惰化系统,来控制油箱无油空间的氧气浓度,但却一直没有适用于机载燃油箱的氧浓度实时监测系统。根据多型机油箱惰化系统试飞经验,总结了基于电化学原理和光谱吸收原理测量系统使用中的问题。依据文献分析,认为基于荧光猝灭原理的传感器将成为下一代机载油箱氧浓度测量系统的核心,并详细介绍了荧光猝灭效应的原理、检测方法、受感部和测量系统框架的研究现状。最后,指出测量系统应该向着轻量化、智能化和高可靠性方向发展。     

MFB50 on-board estimation methodology for combustion control

Due to the increasing request for pollutant emissions reduction, modern closed-loop combustion control strategies require the on-board evaluation of the center of combustion (MFB50), i.e. the angular position where 50% of the injected fuel mass is burned. This work presents an MFB50 estimation algorithm based on engine speed measurement, that can be performed using the same toothed wheel already present on-board. Therefore, this approach is compatible with on-board application and requires no additional hardware cost. The complete methodology has been applied to a Diesel engine mounted on-board a vehicle and the accuracy of the obtained results is compatible with on-board requirements.     

Trajectory control of a high altitude hypervelocity flying vehicle in the midcourse active phase of the flight

An approach to the control of the motion of the center of mass of a high altitude hypervelocity flying vehicle whose engine thrust and aerodynamics strongly depend on the angle of attack in the midcourse active phase of the flight is proposed. This approach provides a basis for the method of the trajectory control of motion. The motion of this flying vehicle is simulated with regard to the disturbed atmosphere. It is shown that the proposed approach can be used to form launching zones of high altitude hypervelocity flying vehicles.