Aerodynamic-Parameter Identification and Attitude Control of Quad-Rotor Model with CIFER and Adaptive LADRC

Current research on quadrotor modeling mainly focuses on theoretical analysis methods and experimental methods,which have problems such as weak adaptability to the environment,high test costs,and long durations.Additionally,the PID controller,which is currently widely used in quadrotors,requires improvement in anti-interference.Therefore,the aforementioned research has considerable practical significance for the modeling and controller design of quadrotors with strong coupling and nonlinear characteristics.In the present research,an aerodynamic-parameter estimation method and an adaptive attitude control method based on the linear active disturbance rejection controller(LADRC)are designed separately.First,the motion model,dynamics model,and control allocation model of the quad-rotor are established according to the aerodynamic theory and Newton-Euler equations.Next,a more accurate attitude model of the quad-rotor is obtained by using a tool called CIFER to identify the aerodynamic parameters with large uncertainties in the frequency domain.Then,an adaptive attitude decoupling controller based on the LADRC is designed to solve the problem of the poor anti-interference ability of the quad-rotor and adjust the key control parameter b0 automatically according to the change in the moment of inertia in real time.Finally,the proposed approach is verified on a semi-physical simulation platform,and it increases the tracking speed and accuracy of the controller,as well as the anti-disturbance performance and robustness of the control system.This paper proposes an effective aerodynamic-parameter identification method using CIFER and an adaptive attitude decoupling controller with a sufficient anti-interference ability.

Dynamic affine formation control of networked under-actuated quad-rotor UAVs with three-dimensional patterns

This paper focuses on the solution to the dynamic affine formation control problem for multiple networked underactuated quad-rotor unmanned aerial vehicles(UAVs)to achieve a configuration that preserves collinearity and ratios of distances for a target configuration.In particular,it is investigated that the quad-rotor UAVs are steered to track a reference linear velocity while maintaining a desired three-dimensional target formation.Firstly,by integrating the properties of the affine transformation and the stress matrix,the design of the target formation is convenient and applicable for various three-dimensional geometric patterns.Secondly,a distributed control method is proposed under a hierarchical framework.By introducing an intermediary control input for each quad-rotor UAV in the position loop,the necessary thrust input and the desired attitude are extracted.In the attitude loop,the desired attitude represented by the unit quaternion is tracked by the designed torque input.Both conditions of linear velocity unavailability and mutual collision avoidance are also tackled.In terms of Lyapunov theory,it is prooved that the overall closed-loop error system is asymptotically stable.Finally,two illustrative examples are simulated to validate the effectiveness of the proposed theoretical results.

H _ index based fault estimation for micro quad-rotor

Taking the attitude control system of micro quad-rotor as a research object, a design scheme of fault estimator based on generalized Kalman-Yakubovic-Popov （GKYP） lemma is put forward to deal with the problem of estimating multiple actuators malfunctions with couplings. Using an H_index and an appropriate algorithm, the goal of weakening the coupling can be achieved by limiting the fault frequency to a certain range, then different kinds of actuator faults can be estimated correctly. The simulations demonstrate the reliability and validity of the proposed method.

An Improved Nonlinear Dynamic Inversion Method for Altitude and Attitude Control of Nano Quad-Rotors under Persistent Uncertainties

Nonlinear dynamic inversion(NDI)has been applied to the control law design of quad-rotors mainly thanks to its good robustness and simplicity of parameter tuning.However,the weakness of relying on accurate model greatly restrains its application on quad-rotors,especially nano quad-rotors(NQRs).NQRs are easy to be influenced by uncertainties such as model uncertainties(mainly from complicated aerodynamic interferences,strong coupling in roll-pitch-yaw channels and inaccurate aerodynamic prediction of rotors)and external uncertainties(mainly from winds or gusts),particularly persistent ones.Therefore,developing accurate model for altitude and attitude control of NQRs is difficult.To solve this problem,in this paper,an improved nonlinear dynamic inversion(INDI)method is developed,which can reject the above-mentioned uncertainties by estimating them and then counteracting in real time using linear extended state observer(LESO).Comparison with the traditional NDI(TNDI)method was carried out numerically,and the results show that,in coping with persistent uncertainties,the INDI-based method presents significant superiority.

Inverse Model Control for a Quad-rotor Aircraft Using TS-fuzzy Support Vector Regression

An inverse model control based on TS-fuzzy support vector regression( TS-fuzzy SVR) for a quadrotor aircraft is developed. The TS-kernel is the product of linear combination of input and a cluster of output corresponding to a cluster of TS-type fuzzy rules. The output of TS-fuzzy SVR is a linear weighted sum of the TSkernels. The dynamical model of the quad-rotor aircraft is derived. A new control scheme combined with TSfuzzy SVR inverse model control and PID control is presented so that the TS-fuzzy SVR inverse model control enhances capabilities of disturbance rejection and the robustness while the PID control enhances fast responsiveness and reliability of the system. Simulation results show the capabilities of the developed control for the attitude system of quad-rotor aircraft.

Predictive Control of Quad-Rotor Delivering Unknown Time-Varying Payloads Based upon Extended State Observer

In this paper, robust control problem is addressed for quad-rotor delivering unknown time-varying payloads. Firstly, the model of a quad-rotor carrying payloads is built. Dynamics of the payloads are treated as disturbances and added into the model of the quad-rotor. Secondly, to enhance system robust-ness, the extended state observer (ESO) is applied to estimate the disturbances from the payloads for feedback compensation. Then a type of predictive controller targeting multiple-input-multiple-output (MIMO) system is developed to degrade the influences caused by sudden changes from load-ing/dropping of the payloads. Finally, by making comparison with the con-ventional cascade proportional-integral-derivative (CPID) and the sliding mode control (SMC) approaches, superiority of the scheme developed is va-lidated. The simulation results indicate that the CPID method shows poor performance on attitude stabilization and the SMC shows input chattering phenomenon even it can achieve satisfied control performances.

Adaptive Backstepping Sliding Mode Trajectory Tracking Control for a Quad-rotor

A quad-rotor aircraft is an under-actuated,strongly coupled nonlinear system with parameter uncertainty and un-modeled disturbance.In order to make the aircraft track the desired trajectory,a nested double-loops control system is adopted in this paper.A position error proportional-derivative(PD) controller is designed as the outer-loop controller based on the coupling action between rotational and translational movement,and an adaptive backstepping sliding mode control algorithm is used to stabilize the attitude.Finally,both the numerical simulation and prototype experiment are utilized to demonstrate the effectiveness of the proposed control system.

A Second-Order Sliding Mode Controller of Quad-Rotor UAV Based on PID Sliding Mode Surface with Unbalanced Load

Quad-rotor unmanned aerial vehicle(UAV)is a typical multiple-input-multiple-output underactuated system with couplings and nonlinearity.Usually,the flying environment is very complex,so that it is impossible for the UAV to avoid effects derived from disturbances and uncertainties.In order to improve the reliability of flight control,we established the dynamic model of quad-rotor UAV by Newton-Euler equation in unbalanced load conditions.Considering external disturbances in the attitude,a second-order sliding mode controller was designed with PID sliding mode surface and Extended State Observer(ESO).The simulation experiments have got good control performance,illustrating the effectiveness of our controller.Meanwhile,the controller was implemented in a quadrotor UAV,which carried a pan-tilt camera for aerial photography.The actual flight experiments proved that this paper dealt with the high stabilization flight control problem for the quad-rotor UAV,which laid a good foundation for autonomous flight of the UAV.

Formation control of quad-rotor UAV via PIO

In this article, the formation control of quad-rotor unmanned aerial vehicle(UAV) via pigeon inspired optimization(PIO) is designed. The nonlinear mathematical model of the quad-rotor UAV is used by applying algebraic graph theory and matrix analysis. A high order consistent formation control algorithm with fixed control topology is designed by using a position deviation matrix to describe its formation. To control the attitude of quad-rotor UAVs, it is difficult to obtain a set of optimal solutions, and hence a PIO based algorithm with variable weight hybridization is proposed. The algorithm is mainly composed of two parts. First, according to the distance between the particles in the iterative process, the inertia weight is dynamically changed,and the coefficient is adjusted to control the degree of influence on its inertia weight. Second, the overall scenario is designed by using MATLAB based simulations which show that the formation control of the quad-rotor UAV is achieved with the help of PIO.

Fractional order adaptive robust formation control of multiple quad-rotor UAVs with parametric uncertainties and wind disturbances

In recent times,multiple Unmanned Aerial Vehicles(UAVs)are being widely utilized in several areas of applications such as agriculture,surveillance,disaster management,search and rescue operations.Degree of robustness of applied control schemes determines how accurate a swarm of UAVs accomplish group tasks.Formation and trajectory tracking controllers are required for the swarm of multiple UAVs.Factors like external environmental effects,parametric uncertainties and wind gusts make the controller design process as a challenging task.This article proposes fractional order formation and trajectory tacking controllers for multiple quad-rotors using Super Twisting Sliding Mode Control(STSMC)technique.To compensate the effects of the disturbances due to parametric uncertainties and wind gusts,Lyapunov function based adaptive controllers are formulated.Moreover,Lyapunov theorem is used to guarantee the stability of the proposed controllers.Three types of controllers,namely fixed gain STSMC and fractional order Adaptive Super Twisting Sliding Mode Control(ASTSMC)methods are tested for the swarm of UAVs by performing the numerical simulations in MATLAB/Simulink environment.From the presented results,it is verified that in presence of wind disturbances and parametric uncertainties,the proposed fractional order ASTSMC technique showed improved robustness as compared to the fixed gain STSMC and integer order ASTSMC.

Backstepping sliding mode tracking control of quad-rotor under input saturation

Purpose–The quad-rotor is an under-actuation,strong coupled nonlinear system with parameters uncertainty,unmodeled disturbance and drive capability boundedness.The purpose of the paper is to design a flight control system to regulate the aircraft track the desired trajectory and keep the attitude angles stable on account of these issues.Design/methodology/approach–Considering the dynamics of a quad-rotor,the closed-loop flight control system is divided into two nested loops:the translational outer-loop and the attitude inner-loop.In the outer-loop,the translational controller,which exports the desired attitude angles to the inner-loop,is designed based on bounded control technique.In consideration of the influence of uncertain rotational inertia and external disturbance,the backstepping sliding mode approach with adaptive gains is used in the inner-loop.The switching control strategy based on the sign functions of sliding surface is introduced into the design procedure with respect to the input saturation.Findings–The validity of the proposed flight control system was verified through numerical simulation and prototype flight experiment in this paper.Furthermore,with relation to the flying,the motor speed is kept in the predetermined scope.Originality/value–This article introduces a new flight control system designed for a quad-rotor.

一种四轴飞行器单目视觉测距算法

为解决四轴飞行器在执行目标检测与跟踪任务时无法判断机身与障碍物或跟踪目标之间安全距离问题,提出一种四轴飞行器单目视觉测距算法,算法融合基于帧间差分技术的水平测距模型与基于小孔成像的垂直测距模型.首先,算法可利用基于YOLOV4-Tiny的目标检测算法识别视频帧中的物体类别,并可在视频帧中框选出被测物体,依据现场环境选择最佳的测距方法进行测距;其次,系统终端执行测距方法,基于被测物体的视频帧成像位置与设定参数之间的差值控制四轴飞行器飞行,并记录飞行数据;最后,通过测距模型对飞行数据进行处理,计算出四轴飞行器在初始位置和最终位置与被测物体之间的距离.通过在特洛(Tello)飞行器平台上的实际飞行验证,实验结果表明所提出的四轴飞行器单目视觉测距算法可以有效分析出视频帧中各物体的景深,测距误差百分比均值为4.07%.在四轴飞行器与障碍物或跟踪目标之间距离较近,却无法评估此距离是否处于安全距离时,所提出的算法可为搭载单目摄像头的四轴飞行器提供可靠的测距技术支持.

可变桨距四旋翼飞行器姿态控制教学设备

针对传统四旋翼飞行器为固定桨距变转速的控制方式,在实际教学中存在非线性、响应慢等问题,给学生完成控制实验带来困难。为达到更好的教学效果,设计与开发一个可变桨距四旋翼飞行器的姿态控制设备,实现了定转速变桨距的控制方式,并完成了基于串级PID的控制律设计与代码实现。设备搭载280级四旋翼,使用基于STM32单片机自行开发的飞行控制器,允许学生编程及嵌入自己的控制律。设备在自动控制专业本科生选修课中进行了应用,获得了理想的教学效果。

基于SolidWorks的陆空两用四旋翼搜救无人机设计与控制

陆空两用搜救无人机应用前景广泛,可以在地面和空中进行有效搜索和救援行动。基于四旋翼飞行器设计了一种陆空两用四旋翼搜救无人机,完成了飞行平台和行走平台结构设计,编制了飞控的超声波定高系统和光流定位系统的算法程序,搭建了搜救系统。利用SolidWorks建立了三维建模,并对关键受力部件进行了有限元分析。对后续陆空两用四旋翼搜救无人机的研究具有重要的指导意义。

船用起重机四旋翼减摇吊钩动力学特性

【目的】设计一种船用起重机减摇装置并探究其防摆机理,以期解决当前船用起重机吊装过程的摇摆问题。【方法】设计一种船用起重机四旋翼减摇吊钩装置,建立船舶-起重机-四旋翼减摇吊钩的动力学模型,并考虑风载荷的影响。设计自适应模糊比例-积分-微分(PID)控制策略应用于四旋翼减摇吊钩控制器,根据摆角偏差量控制相应电机转动产生抑制吊重摆动的推力,实现摆角在线实时控制。通过动力学仿真分析和实验验证,探究其减摇特性和运动规律。【结果】在船舶激励下吊重面内和面外摆角分别减少约66.8%和69.7%,吊重摆动投影在x和y轴最大偏移量平均降低62.5%。自适应模糊PID控制策略下的四旋翼减摇吊钩较PID控制响应速度提高25.0%,稳态性能提升13.0%。通过实验与仿真对比分析,吊重摆角曲线趋势基本吻合,在16 s时吊重趋近于稳定,验证了四旋翼减摇吊钩动力学模型的准确性。【结论】四旋翼减摇吊钩能有效抑制吊重摆动,可为船用起重机轻载吊装防摆研究提供新的可行性减摇方案。

基于串级线性自抗扰的四旋翼姿态控制方法

针对四旋翼无人机姿态调整过程中,由于参数不确定性及外界环境干扰,往往给姿态控制带来一定困难。本文研究提出一种基于串级线性自抗扰的四旋翼姿态控制方法。首先建立四旋翼无人机的动力学姿态模型,提出采用串级PID双环路控制架构,将姿态控制任务分解为内外两个环路。采用Levant微分器提取控制参量,以强化跟踪能力。此外,对原线性自抗扰控制器进行优化,旨在更好地消除外界随机扰动对系统的影响。利用MATLAB Simulink环境对提出的控制方法进行模拟,结果表明相比传统方法,该方法能更好地抑制系统受扰动引起的影响,增强系统对期望信号的跟踪能力,从而明显提高了四旋翼无人机姿态调整的精度与稳定性,以及四旋翼无人机姿态控制的精度和鲁棒性。

变质量负载四旋翼无人机抗风性研究

四旋翼无人机已越来越多的应用于农业植保方面,针对其随着农药量的减少以及外部风扰影响下导致系统的飞行性能的问题,设计了一种积分反步控制法与串级RBF神经网络PID控制相结合的控制方案。方案具有内外环结构,在外环采用积分反步法,对水平位置和高度进行控制;内环采用串级RBF神经网络PID控制,依靠神经网络自学习性对PID参数动态整定实现对姿态角的控制。仿真结果表明,与常规PID控制相比,该方案随外界干扰的波动范围更小,误差更小,证明了该方案的抗干扰性更强。

四旋翼巡检无人机固定时间滑模姿态控制

为了提高突发状况下电力巡检四旋翼无人机快速姿态机动性能,基于积分滑模、齐次理论及固定时间稳定理论,提出了一种四旋翼无人机的固定时间滑模姿态控制方法。首先,基于积分滑模与齐次理论,设计了可固定时间收敛且非奇异的滑模面。随后,提出了保证滑模面固定时间收敛的控制器。基于李雅普诺夫稳定性理论与齐次理论,证明了所提闭环系统的固定时间稳定性。相比传统有限时间滑模控制方法,所提出的固定时间滑模控制方法可以保证控制误差的收敛时间受限于固定常数,因此无论在小角度与大角度机动情况下,所提的方法都能够保证控制误差的快速收敛。其次,基于积分滑模的设计,所提出的固定时间滑模控制方法解决了传统终端滑模的奇异问题。最后,通过仿真对比,验证了所提方法的优势。

基于SSA-MPC-SMC的四旋翼无人机轨迹跟踪

为解决六自由度四旋翼无人机(UAV)在轨迹跟踪控制过程中,因为存在复杂的外部未知干扰,而使系统的轨迹跟踪精度产生较大波动的问题,设计了一种新型的级联双闭环控制系统,分别针对速度误差和位置姿态误差。首先,使用模型预测控制(MPC)设计速度闭环控制器,麻雀搜索算法(SSA)因具有快速收敛性和强鲁棒性,被应用于MPC滚动优化进程求取最优解。为了克服MPC存在的计算量过大的缺点,使用滑模控制(SMC)分别设计位置和姿态动力学控制器。SMC对外界干扰不敏感、鲁棒性强、无需精确建模,从而解决了UAV外部干扰不确定以及难以准确建模的问题。使用饱和函数替代符号函数,使实际系统的输入具有连续性,从而有效地减轻SMC中的高频抖振现象。最后使用李雅普诺夫理论验证所提出的SSA-MPC控制器的稳定性。实验结果表明:在受到复杂的外部未知干扰以及参数不确定的情况下,所提出的方法能够保证六自由度四旋翼UAV实现高精度跟踪,且控制效果明显优于传统单一控制器构成的UAV控制系统。所提出的级联控制器可以有效地实现复杂的外部未知干扰下的四旋翼UAV轨迹跟踪。

Analysis and Research on Aerodynamic Characteristics of Quad Tilt Rotor Aircraft

For the quad tilt rotor aircraft, a computational fluid dynamics method based on multiple reference frames (MRF) was used to analyze the influence of aerodynamic layout parameters on the aerodynamic characteristics of the quad tilt rotor aircraft. Firstly, a numerical simulation method for the interference flow field of the quad tilt rotor aircraft is established. Based on this method, the aerodynamic characteristics of isolated rotors, rotor combinations at different lateral positions on the wing, and rotor rotation directions under different inflow velocities were calculated and analyzed, in order to grasp their aerodynamic interference laws and provide reference for the design and control theory research of such aircraft.