改进扩展卡尔曼滤波的四旋翼姿态估计算法

为了提高标准扩展卡尔曼姿态估计算法的精确度和快速性,将运动加速度抑制的动态步长梯度下降算法融入扩展卡尔曼中,提出一种改进扩展卡尔曼的四旋翼姿态估计算法。该算法在卡尔曼测量更新中采用梯度下降法进行非线性观测,消除标准扩展卡尔曼算法在线性化时带来的线性化误差,提高算法的准确性和快速性;对梯度下降法的梯度步长进行动态处理,使算法步长与四旋翼飞行器的运动合角速度成正比,增强微型四旋翼飞行器姿态解算的动态性能;对强机动运动过程中机体产生的运动加速度进行抑制处理,消除运动加速度对姿态解算的不利影响,提高了微型四旋翼飞行器姿态解算的跟踪精度。为了验证所设计算法的可行性和有效性,基于STM32单片机搭建四旋翼实验平台系统进行实时在线性能验证。结果表明,所设计算法能提高四旋翼飞行器在强机动、高速运动情况下的姿态跟踪精度、动态性能,增强姿态融合算法的抗干扰性,保证微型四旋翼飞行器的稳定飞行。     

四旋翼无人机的多模型故障诊断

四旋翼无人机是一个强耦合非线性被控对象,准确地判断故障情况,并及时调整控制器参数对无人机的安全飞行具有重要的意义。针对四旋翼无人机的执行器部分失效故障,提出了一种多模型在线故障诊断方法。该方法根据不同故障模式建立故障模型集,通过模型集的并联运行对无人机工作模式进行在线监测。仿真结果表明,对于单旋翼执行器部分失效故障,该方法能够快速准确地获得故障模型参数。     

Quadrotor path planning using A* search algorithm and minimum snap trajectory generation

In this study, we propose a practical path planning method that combines the A* search algorithm and minimum snap trajectory generation. The A* search algorithm determines a set of waypoints to avoid collisions with surrounding obstacles from a starting to a destination point. Only essential waypoints (waypoints necessary to generate smooth trajectories) are extracted from the waypoints determined by the A* search algorithm, and an appropriate time between two adjacent waypoints is allocated. The waypoints so determined are connected by a smooth minimum snap trajectory, a dynamically executable trajectory for the quadrotor. If the generated trajectory is invalid, we methodically determine when intermediate waypoints are needed and how to insert the points to modify the trajectory. We verified the performance of the proposed method by various simulation experiments and a real-world experiment in a forested outdoor environment.     

Quaternion-based adaptive control for trajectory tracking of quadrotor unmanned aerial vehicles

The problem of trajectory tracking of aerial vehicles with four rotors and dynamic parameter uncertainties is addressed in this article. By exploiting the cascade structure of the translational and attitude dynamics of the quadrotor, a nonlinear hierarchical adaptive control is proposed. The attitude control law is designed based on the unit quaternion, therefore, the singularities of the Euler angles and angle-axis representation are avoided. Instead of relying on the stability properties of time-varying cascade systems, the stability of the whole closed-loop system is proven by an appropriate Lyapunov function. In addition, a novel method to compute the desired orientation based on the desired Cartesian trajectories and position control inputs is proposed. A set of simulations results are presented to assess the performance of the proposed adaptive controller.     

Tracking control of vertical taking-off and landing vehicles with parametric uncertainty

This paper considers the position and attitude tracking control of a quadrotor with inertia parameter uncertainty. With the aid of the cascade structure of the dynamics of the system, an immersion and invariance observer is proposed to estimate the unknown mass of the system first. Secondly, a saturation controller is designed for the thrust force. Thirdly, a virtual controller is proposed for the angular velocity of the quadrotor with the aid of a nonlinear transform of the Euler angles. Finally, adaptive and robust controllers are proposed for the torque input of the quadrotor to deal with the unknown inertia moment of the system. Simulation results show the effectiveness of the proposed algorithms.     

基于四旋翼无人机的输电线路巡检系统研究

针对输电线路短途巡检的应用需求,解决常规巡检手段低效、安全、技术门槛等问题,以四旋翼无人机为载体,搭载影像采集设备进行航拍巡视,搜索、定位、采集线路缺陷和隐患的影像数据。根据线路杆塔坐标信息,预设航迹点实现自主飞行巡检;以设备回传的杆塔实时影像为操作指导,利用手动飞行模式实现线路关键部件的影像采集。该系统提升了线路状态管理、应急指挥的便利性,为输电线路的安全评估、灾前排查、事故预警、灾后抢修,乃至状态检修和全寿命周期管理提供全方位的信息支持。     

四轴飞行器姿态控制系统设计

由于四轴飞行器系统具有不稳定、非线性、强耦合等特性,所以姿态控制在飞行器完成飞行任务的过程中尤为 重要。本文着重对飞行器姿态控制算法进行研究。首先对飞行器建立合理的坐标系,根据角度传感器所测得的角度,得到以 四元数表示的姿态转换矩阵。根据空气动力学原理,牛顿第二定律,对飞行器建立动力学模型,得到四个独立通道的控制输入 量,该控制输入量可以通过控制四轴飞行器各个方向的加速度来对飞行器进行姿态控制。     

基于四旋翼无人机的二次屏柜巡检系统

随着人们对于电力的需求量越来越大,相应的电力巡检的要求也越来越高。文中设计了基于四旋翼无人机的二次屏柜巡检系统。为解决无人机在室内GPS拒止问题,文中通过AprilTag算法配合传感器高度信息,实现无人机室内飞行路径规划功能、姿态矫正、自主飞行;在机载树莓派内存入任务程序,该程序将利用飞控和传感器实现对任务地点二维码的寻找和判断,并在达到指定点后执行拍摄任务;通过局域网将采集的图像传输到地面服务器,并输入到预先训练好的CNN网络模型中进行异常检测;依据识别结果判断二次屏柜是否工作正常,并将检测结果上传到显示平台。最终项目在贵州铜仁变电站室内二次屏柜现场测试成功。     

微型四旋翼无人机模糊PID 控制

为解决微型四旋翼无人机控制系统存在的鲁棒性差和控制精度低的问题,提出一种模糊PID控制方法。建立微型四旋翼无人机系统动力学数学模型和电机模型,在系统模型的基础上设计模糊PID控制器。通过Matlab/Simulink仿真和飞行试验对所设计的模糊PID控制器的有效性进行验证。仿真实验表明,该算法能提高系统的抗干扰性能和控制精度。飞行试验结果表明,模糊PID控制器可以有效地控制微型四旋翼无人机。     

四旋翼飞行器建模与PID控制器设计

为了实现对四旋翼飞行器的稳定飞行控制,对四旋翼飞行器建立了动力学数学模型,并采用准LPV法将非线性模型线性化,在建立的动力学模型基础上,对飞行器垂直速率、俯仰速率、横滚速率、偏航速率四个独立通道上分别设计了PID控制器.并通过Matlab/Simulink软件进行控制系统仿真,并对仿真结果进行分析,仿真结果验证了PID算法的有效性.