直升机飞控系统集成仿真平台开发

研究直升机飞行控制系统的设计开发需求,根据系统集成的开发理念,实现VC++开发环境下Matlab/Simulink和三维实时视景仿真软件Vega的综合集成,利用现有成熟软件工具,在一台普通PC机上开发了一个集仿真管理、控制算法设计与优化、三维可视化于一体的直升机飞行控制系统仿真平台,对直升机飞行控制系统的设计开发提供集成平台支持。集成平台可充分满足用户的仿真任务需求,可提高系统开发效率,同时具有通用的集成开发思路对类似系统研制和开发具有一定的参考价值。     

无人直升机实时机载和地面站软件架构设计

研究了无人直升机飞行控制系统实时软件系统设计架构,针对机载嵌入式飞控计算机系统和地面站计算机系统,提出了基于VxWorks实时操作系统的多线程任务机载软件设计方案和基于WindowsXP操作系统的地面站软件设计方案,有助于加快完成无人直升机飞行控制系统的设计和验证。机载系统软件设计为数据采集和测量、伺服舵机驱动、飞行控制与发动机控制实现、通信和数据请求存储等功能。地面站系统软件设计为与机载系统的数据通信、终端用户操控,以及实时飞行状态监视等功能。利用组件对象模型设计技术实现了系统软件设计的模块化、软件结构分层组件化,方便了软件系统的集成与扩展。采用多任务线程机制,有效地满足了飞行控制系统实时性要求。利用实时操作系统的定时器任务机制,确保飞行模式的任务管理和调度。依据所提出的软件设计架构完成了实时机载软件和地面站软件组件模块的设计与开发,而且软件集成快捷方便。研究成果已成功应用于某型无人直升机飞行控制系统。     

基于Dubins曲线的无人直升机轨迹规划

为提高无人直升机的控制性能,提出了一种基于Dubins曲线的轨迹规划算法,并对其各个部分的实现进行了研究和设计。该算法利用Dubins曲线原理对定点飞行任务的两点或者多点目标进行分析计算,寻找出一条最短的飞行路径,从而提高了飞行效率。根据无人直升机系统多变量、非线性和强耦合的特点,采用串级PID方法设计了飞行控制器,该控制器能够修正无人直升机的姿态和位置,从而提高了轨迹规划的稳定性和准确性。最后,以某小型无人直升机为实验平台表明了该轨迹规划算法和控制器的可行性。     

无人机综合检测与仿真系统

针对无人机系统研制过程中测试及仿真验证的需求,设计了一种基于PowerPC硬件平台和VxWorks软件平台的无人机综合检测与仿真系统.该系统以仿真计算机为主体,在考虑综合检测与仿真两大功能需求的基础上,对其进行软硬件设计.本文从系统整体研制方案、硬件设计与实现、系统通信协议、软件设计与实现等4个方面具体阐述系统工作原理及设计思路.最后搭建了不同的应用环境对该系统进行测试和验证,通过数据分析证明了该系统的实用性,并将有效地提高无人机飞行控制系统的研制和开发效率.     

Control of a laboratory 3-DOF helicopter: Explicit model predictive approach

A helicopter flight control system is a typical multi-input, multi-output system with strong channel-coupling and nonlinear characteristics. This paper presents an explicit model predictive control (EMPC) for attitude regulation and tracking of a 3-Degree-of-Freedom (3-DOF) helicopter. A state-space representation of the system is established according to the characteristics of each degree-of-freedom motion. Multi-Parametric Quadratic Programming (MPQP) and online computation processes for explicit model predictive control and controller design for a 3-DOF helicopter are discussed. The controller design for set-point regulation and tracking time-varying reference signals of a 3-DOF helicopter are presented respectively. Numerical study of explicit model predictive control for attitude regulation and tracking of a 3-DOF helicopter are conducted. A hardware-in-the-loop experimental study of explicit model predictive control of a 3-DOF helicopter is made. To analyze the performances of an EMPC controlled helicopter system, an Active Mass Disturbance System and manual interference are considered in comparison with PID scheme. Numerical simulation and HIL experimental studies show that explicit model predictive control is valid and has satisfactory performance for a 3-DOF helicopter.     

Nonlinear dynamic modeling and control of a small-scale helicopter

A test bench for experimental testing of the attitude control of a small-scale helicopter is constructed. A nonlinear model with 10 states is developed for this experimental setup. The unknown model parameters are estimated using the extended Kalman filter with flight test data of the helicopter operating on the test bench. In this work, it is proved that the nonlinear helicopter dynamic model may be globally feedback linearized using the dynamic feedback linearization technique. In order to satisfy multiple closed-loop performance specifications simultaneously, a controller is proposed by applying the Convex Integrated Design (CID) method to the feedback linearized model. Finally, the controller is tested in simulation demonstrating the closed-loop performance of the proposed controller.     

An acceleration measurements-based approach for helicopter nonlinear flight control using Incremental Nonlinear Dynamic Inversion

Due to the inherent instabilities and nonlinearities of rotorcraft dynamics, its changing properties during flight and the engineering difficulties to predict its aerodynamics with high levels of fidelity, helicopter flight control requires the application of special strategies. These strategies must allow to cope with the nonlinearities of the system and assure robustness in the presence of inaccuracies and changes in configuration.In this paper, a novel approach based on an Incremental Nonlinear Dynamic Inversion is applied to simplify the design of helicopter flight controllers. With this strategy, by employing the feedback of acceleration measurements to avoid the need for information relative to any aerodynamic change, the control system does not need any model data that depends exclusively on its states, thus enhancing its robustness to model uncertainties.The overall control system is tested by simulating two tasks with distinct agility levels as described in the ADS-33 helicopter handling qualities standard. The analysis shows that the controller provides an efficient tracking of the commanded references. Furthermore, with the robustness properties verified within the range of inaccuracies expected to be found in reality, this novel method seems to be eligible for a potential practical implementation to helicopter vehicles.     

直升机光传操纵地面物理仿真平台的开发

该文基于某型武装直升机控制增稳飞控系统，建立了直升机光传操纵地面物理仿真平台，着重开发了两种典型的光传技术。并叙述了仿真平台的结构配置及主要组成部件开发实现。实现了具有人机交互功能的直升机光传操纵可视化仿真，并通过光传与电传的特性对比验证了两种光传技术的有效性。从而为我国直升机光传系统的实现，提供了有效的地面开发平台。     

无人直升机的姿态增强学习控制设计与验证

针对小型无人直升机的姿态控制问题,考虑到现有基于模型的控制方法对直升机动力学模型的先验信息依赖较大,以及未建模动态系统的影响等问题,设计了一种基于增强学习(RL)的飞行控制算法.仅利用直升机的在线飞行数据,补偿了未建模不确定性的影响.同时为了抑制外界扰动,提高系统的鲁棒性,设计了一种基于误差符号函数积分的鲁棒(RISE)控制算法.将两种算法结合,并利用基于Lyapunov分析的方法,证明了无人机姿态控制误差的半全局渐近收敛.最后在无人直升机飞行控制实验平台上,进行了姿态控制的实时实验验证.实验结果表明,本文提出的控制方法具有良好的控制效果,对系统不确定性和外界风扰具有良好鲁棒性.     

直升机飞行控制器设计与仿真

为了改善直升机飞行控制系统的性能,研究了其在前飞状态下的模糊平滑切换控制方法和仿真验证问题。以ADS-33D水平1操纵品质要求为设计目标,建立直升机不同平衡点的线性子模型,采用基于遗传算法的H∞控制器设计方法设计各局部控制器,应用模糊平滑切换策略设计全局控制器,实现直升机在不同速度下的飞行控制,保证了控制过程的平滑性,并用数学方法证明了系统的稳定性。仿真结果表明,所设计的直升机飞行控制器达到了ADS-33D水平1操纵品质要求。     

Design and implementation of an autonomous flight control law for a UAV helicopter

In this paper, we present the design and implementation of an autonomous flight control law for a small-scale unmanned aerial vehicle (UAV) helicopter. The approach is decentralized in nature by incorporating a newly developed nonlinear control technique, namely the composite nonlinear feedback control, together with dynamic inversion. The overall control law consists of three hierarchical layers, namely, the kernel control, command generator and flight scheduling, and is implemented and verified in flight tests on the actual UAV helicopter. The flight test results demonstrate that the UAV helicopter is capable of carrying out complicated flight missions autonomously.     

Helicopter trimming and tracking control using direct neural dynamic programming

This paper advances a neural-network-based approximate dynamic programming control mechanism that can be applied to complex control problems such as helicopter flight control design. Based on direct neural dynamic programming (DNDP), an approximate dynamic programming methodology, the control system is tailored to learn to maneuver a helicopter. The paper consists of a comprehensive treatise of this DNDP-based tracking control framework and extensive simulation studies for an Apache helicopter. A trim network is developed and seamlessly integrated into the neural dynamic programming (NDP) controller as part of a baseline structure for controlling complex nonlinear systems such as a helicopter. Design robustness is addressed by performing simulations under various disturbance conditions. All designs are tested using FLYRT, a sophisticated industrial scale nonlinear validated model of the Apache helicopter. This is probably the first time that an approximate dynamic programming methodology has been systematically applied to, and evaluated on, a complex, continuous state, multiple-input multiple-output nonlinear system with uncertainty. Though illustrated for helicopters, the DNDP control system framework should be applicable to general purpose tracking control.     

Trajectory linearization control for a miniature unmanned helicopter

Trajectory linearization control (TLC) approach is applied to design a nonlinear trajectory tracking controller for a miniature unmanned helicopter. The controller is based on nonlinear model derived from Newton-Euler equations, with collective and cyclic pitches being regarded as actual controls. Via model simplifications, the nonlinear helicopter model can be transformed into a cascaded form including four subsystems. Corresponding with the simplified cascaded structure, the proposed controller is constructed by synthesizing TLC designs for subsystems. Each of them includes designs of a pseudo-inversion and an error regulator. A summarized TLC algorithm for the unmanned helicopter is listed briefly after the detailed controller design process. Simulation results are provided to demonstrate performances of the closed-loop system.     

Pitch Loop Control of a VTOL UAV Using Fractional Order Controller

Pitch loop control is the fundamental tuning step for vertical takeoff and landing (VTOL) unmanned aerial vehicles (UAVs), and has significant impact on the flight. In this paper, a fractional order strategy is designed to control the pitch loop of a VTOL UAV. First, an auto-regressive with exogenous input (ARX) model is acquired and converted to a first-order plus time delay (FOPTD) model. Next, based on the FOPTD model, a fractional order [proportional integral] (FO[PI]) controller is designed. Then, an integer order PI controller based on the modified Ziegler-Nichols (MZNs) tuning rule and a general integer order proportional integral derivative (PID) controller are also designed for comparison following three design specifications. Simulation results have shown that the proposed fractional order controller outperforms both the MZNs PI controller and the integer order PID controller in terms of robustness and disturbance rejection. At last, ARX model based system identification of AggieAir VTOL platform is achieved with experimental flight data.     

直升机强跟踪自适应变稳控制器设计

变稳控制是直升机飞行模拟的关键技术之一, 气动参数的不确定性是其设计的困难所在. 对此, 提出了利用双目标直升机模型构造原型直升机的强跟踪自适应变稳控制器, 它将强跟踪的反馈补偿机构和自适应控制参数设计相分离, 简化了控制设计, 同时实现了提高自适应参数修正过程的系统稳定裕度和显著降低跟踪误差的目的. 仿真实验结果验证了所提出方法的有效性和可行性.     

A HIL Testbed for Initial Controller Gain Tuning of a Small Unmanned Helicopter

A Hardware-In-The-Loop (HIL) testbed design for small unmanned helicopters which provides a safe and low-cost platform to implement control algorithms and tune the control gains in a controlled environment is described. Specifically, it allows for testing the robustness of the controller to external disturbances by emulating the hover condition. A 6-DOF nonlinear mathematical model of the helicopter has been validated in real flight tests. This model is implemented in real-time to estimate the states of the helicopter which are then used to determine the actual control signals on the testbed. Experiments of the longitudinal, lateral and heading control tests are performed. To minimize the structural stress on the fuselage in case of controller failure or a subsystem malfunction, a damping system with a negligible parasitic effect on the dynamics of the helicopter around hover is incorporated. The HIL testbed is capable of testing the helicopter in hover, as well as on any smooth trajectories such as cruise flight, figure-8, etc. Experimentally tuning the controller on the HIL testbed is described and results in a controller which is robust to the external disturbances, and achieves an accuracy of ±2.5 cm in the position control on the longitudinal and lateral trajectory tracking, and ±5 deg accuracy around the yaw axis on the heading trajectory tracking.     

一种航天飞控计算自动化平台的设计与实现

航天器飞行控制计算是航天器测控任务实施过程的重要内容,针对航天器飞行控制计算软件的自动化实现与调度问题,基于功能分治的思想设计实现了一种支持多星任务、手动与自动模式并存、自动调度与不可自动调度方式并存的自动化调度平台软件,给出了其设计思想、实现方法,研究结果对航天测控软件的开发有一定的参考价值.     

无人直升机悬停至前飞切换控制

模态切换控制是无人直升机实现全天候自主飞行的关键,实现飞行模态闯快速平稳的切换是无人直升机控制器设计的主要目的。针对无人直升机悬停至前飞过切换程时高度不能保持现象和对象无人直升机高度一航向通道之间存在耦合,提出了前飞速度和航向角速率补偿设计高度通道控制律,升降速度和总距风扇联动关系补偿设计航向通道控制律。最后通过大量仿真试验验证了此方法的可行性和有效性。