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    Welcome to the website of the Reliable Flight Control Group led by Associate Prof. Quan Quan. The Reliable Flight Control Group belongs to the Software and Control Lab led by Prof. Kai-Yuan Cai, which is further a part of the Department of Automatic Control, School of Automation Science and Electrical Engineering, Beihang University.

    Our mission is to make aircraft (multirotor and fixed wing) more reliable by robust navigation, flight control, and health and safety evaluation, etc.

    Reliable Flying Makes Life Easier!

News & Events

2020 / 11 / 25

Congratulations, Rfly Group won the first prize in an Innovation Challenge on Precise Aerial Docking. Also, Rfly Group won the second prize in a Flight Challenge on Precise Aerial Docking.

2020 / 08 / 30

Congratulations, an excellent student Jinrui Ren, graduated from our lab

2020 / 06 / 30

RflySim, launched by our Group, is an ecosystem or a toolchain mainly for unmanned systems’ control and safety testing following the idea of Model-Based Design (MBD). Now, it is online. https://rflysim.com

2020 / 06 / 30

English book ” Quan Quan, Xunhua Dai and Shuai Wang. Multicopter Design and Control Practice. Springer, Singapore, 2020” is online.

Welcome to visit https://www.springer.com/gp/book/9789811531378

2020 / 01 / 15

Congratulations, four excellent students Xunhua Dai, Mengxin Li, Xudong Yan and Zeqing Ma, graduated from our lab

2020 / 01 / 15

English book ” Quan Quan, Kai-Yuan Cai. Filtered Repetitive Control with Nonlinear Systems. Springer, Singapore, 2020” is online.

Welcome to visit https://www.springer.com/in/book/9789811514531 for more information. Download 

2019 / 10 / 29

Drone team leader at Meituan-Dianping visited our group

2019 / 10 / 26-27

Group trip to Gubei water town

2019 / 10 / 21

Our group attended 2019 CubePilot Conference(2019全球无人机开发者大会)

2019 / 10 / 19

Professor Florian Holzapfel visited our group

2019 / 10 / 01

New Journal Paper Published

Xunhua Dai, Quan Quan, Jinrui Ren and Kai-Yuan Cai. Efficiency Optimization and Component Selection for Propulsion Systems of Electric Multicopters. IEEE Transactions on Industrial Electronics, vol. 66, no. 10, pp. 7800–7809, 2019.

2019 / 09 / 20

New Journal Paper Published

Ke Dong, Quan Quan and W. Murray Wonham. Failsafe mechanism design for autonomous aerial refueling using state tree structures. Unmanned Systems, 2019, 07(04): 261–279.[Code]

2019 / 09 / 17

New Journal Paper Published

Bai-Hui Du, Andrey Polyakov, Gang Zheng and Quan Quan. Quadrotor trajectory tracking by using fixed-time differentiator. International Journal of Control, 2019, 92(12): 2854–2868.

2019 / 08 / 02

Professor Quan is invited to attend 2019 ROS summer school in Hefei and give a talk.

2019 / 08 / 01~04

Multicopter Model Based Design Course (the Second round) in Hefei.

2019 / 07 / 26

Professor Quan’ group obtains the Second Prize in the 2nd "Zhangfang Cup" 5G Application Competition in Zhejiang Division.

2019 / 04 / 22

Mr.Philip Rowse is invited by Professor Quan to give a talk entiled "Recent Trend & Hot Topics in Drone Industry"

2019 / 03 / 22

Professor Quan Quan and our group visit and communicate with T-MOTOR

2019 / 02 / 24

Multicopter Model Based Design Face-to-Face Courses in Hefei

2019 / 02 / 01

New Journal Paper Published

Xunhua Dai, Quan Quan, Jinrui Ren and Kai-Yuan Cai. An Analytical Design Optimization Method for Electric Propulsion Systems of Multicopter UAVs with Desired Hovering Endurance. IEEE/ASME Transactions on Mechatronics, 2019, 24: 228-239.

2019 / 01 / 15

Congratulations, three excellent students Haibiao Ma, Hepeng Zhang and Zhenglong Guo, graduated from our lab

More new students will join us this year. See "PEOPLE" page for detail.

2018 / 11 / 7

Congratulations, two excellent postdoctors Qian Fu and Guangxun Du has been out of post-doctoral stations from our lab

More new students will join us this year. See "PEOPLE" page for detail.

2018 / 10 / 15

Our group attended 2018 ArduPilot Conference(第二届ArduPilot全球无人机开发者大会)

Professor Quan Quan and our group were invited to give a talk in ArduPilot Conference in Suzhou.

2018 / 03 / 21

Congratulations, four excellent students Yao Luo, jing Zhang, jianing Fu and Baihui Du, graduated from our lab

More new students will join us this year. See "PEOPLE" page for detail.

2018 / 03 / 20

The Chinese version of book Introduction to Multicopter Design and Control (《多旋翼飞行器设计与控制》) is published.

The book is available at [Amazon] [Taobao] [Dangdang] [JD].

2017 / 12 / 16

PX4 Autopilot Team visited our group

PX4 Autopilot Team Dr. Lorenz Meier and Mr. Kevin Sartori visited our group. Professor Quan Quan and Ph.D. candidate Xunhua Dai were invited to give a talk in PX4’s meetup in Beijing. [PPT] [YouTube] [Youku]

2017 / 07 / 06

The English book Introduction to Multicopter Design and Control is published.

Welcome to visit http://www.springer.com/in/book/9789811033810 for more information. [Download]

2017 / 07 / 05

New Journal Paper Published

Dongjie Shi, Xunhua Dai, Xiaowei Zhang, and Quan Quan. "A Practical Performance Evaluation Method for Electric Multicopters" IEEE/ASME Transactions on Mechatronics, 2017, 22(3):1337-1348. [pdf]

2017 / 07 / 05

New Journal Paper Published

Zhiyao Zhao, Quan Quan, Kai-Yuan Cai. "A health performance prediction method of large-scale stochastic linear hybrid systems with small failure probability" Reliability Engineering and System Safety, 2017, 165: 74–88. [pdf]

2017 / 04 / 06

Online course (MOOC) for Introduction to Multicopter Design and Control is available (in Chinese)

For more detail, visit Cloud classroom of Netease (网易云课堂 搜索“多旋翼”) http://study.163.com/course/introduction/1003715005.htm

2017 / 03 / 21

All English and Chinese PPTs of Introduction to Multicopter Design and Control have been released

The textbook is coming soon, for more detail, visit Course Center

2017 / 03 / 20

Congratulations, three excellent students Jiang Yan, Dongjie Shi and Yangguang Cai, graduated from our lab

More new students will join us this year. See "PEOPLE" page for detail.

2016 / 12 / 14

Prof. Quan Quan starts his one-year visitation (2016 / 12 / 14 - 2017 / 12 / 14) to the Systems Control Group at University of Toronto hosted by Professor W.M. Wonham.

2016 / 11 / 27

New Journal Paper Published

Zi-Bo Wei, Quan Quan, Kai-Yuan Cai. "Output Feedback ILC for a Class of Nonminimum Phase Nonlinear Systems with Input Saturation: An Additive-state-decomposition-based Method" IEEE Transactions on Automatic Control., 2017, 62(1):502-508. [pdf]

   2016 / 11 / 07 ~ 2016 / 11 / 11

Visiting and communication at Shenzhen

     Professor Quan is invited by International UAS Standardization Association http://www.uasstd.com/ to give a three-day course on multicopter design and control for engineers from companies and Institute in China.
     Then, the Reliable flight control group is invited to visit DJI-Innovations and Dongguan Songshan Lake robot industry base.

   2016 / 10 / 01

Flying Performance Evaluation Website Is Online

www.flyeval.com is a performance evaluation website for multicopters . Users can obtain the detail evaluations after providing the body frame parameters, the environment parameters and the propulsion system parameters. [visit]

2016 / 09 / 15

Welcome Prof. Danny Lee from Singapore Polytechnic to communicate with our group.

His group presented an automated battery swapping system for quadcopters which includes the design concept of the battery swapping mechanisms and the precise landing control with test results.   [detail]

2016 / 09 / 01

Welcome new students to join us!

Four new students joined us this year. See "PEOPLE" page for detail.

2016 / 08 / 01

New Journal Paper Published

Zi-Bo Wei, Xunhua Dai, Quan Quan, Kai-Yuan Cai. "Drogue Dynamic Model under Bow Wave Effect in Probe and Drogue Aerial refuelling" IEEE Transactions on Aerospace and Electronic Systems, 2016, 52(4): 1728-1742. [pdf]

2016 / 07 / 11 ~ 2016 / 07 /24

Dr. Gang Zheng at INRIA-Lille Nord Europe visited our group

Dr. Gang Zheng visited our group and gave a talk "Observability Analysis and Observer Design for Linear Time-Delay Systems" for students at Beihang University. This visitation was supported by Laboratoire International Associé (中文:北航中法联合实验室).

2015 / 07 / 18

Group trip to Huludao

2016 / 07 / 08 ~ 2016 / 07 / 14

The Series courses on multicopter design and control for a national summer school

Associate Prof. Quan Quan is invited to give the Series courses on multicopter design and control for a national summer school held by National University of Defense Technology in Changsha, China.

2016 / 5 / 24

New Journal Paper Published

Xunhua Dai,Zi-Bo Wei, Quan Quan. "Modeling and simulation of bow wave effect in probe and drogue aerial refueling" Chinese Journal of Aeronautics, 2016, 29(2) : 448-461.   [detail]  [pdf]

2016 / 04 / 28

3DR Robotics CEO Mr. Chris Anderson visited our group

2016 / 03 / 01

New Journal Paper Published

Quan Quan , Guang-Xun Du, Kai-Yuan Cai. "Proportional-Integral Stabilizing Control of a Class of MIMO Systems Subject to Nonparametric Uncertainties by Additive-State-Decomposition Dynamic Inversion Design." IEEE/ASME Transactions on Mechatronics,2016, 21(2) :1092 – 1101.   [detail]  [pdf]

2016 / 02 / 01

New Journal Paper Published

Quan Quan, Kai-Yuan Cai. "A New Continuous-Time Equality-Constrained Optimization Method to Avoid Singularity" IEEE TNNLS, 2016, 27(2): 262-272   [detail]  [pdf]

2015 / 12 / 19

Prof. W.M. Wonham visited our group

The famous automatic control expert, professor of Toronto university, Prof. W.M. Wonham visited our group between 05/12/2015 to 19/12/2015. [detail]

Video Demonstration

2021 / 03 / 07

Fast Light Show Design Platform for K-12 Children

    This paper aims to present a drone swarm light show design platform to support STEAM (science, technology, engineering, art and mathematics) education for K-12 children. With this platform, children can use this platform to design a drone swarm light show easily. To this end, the architecture of this platform contents three layers: UI layer, command layer, and physical layer. The UI layer has an easy-to-use interface for children. Children can feed parameters about the light show by clicking buttons and dragging sliders of four tracks. All actions designed for the swarm in the UI layer will be generated automatically in the form of the drone’s desired trajectories through the command layer. The physical layer includes a router for communication and a drone swarm for the light show. Our experimental results demonstrate that this platform works efficiently and suits for being applied to real STEAM education.   [YouTube] [Youku]

2020 / 12 / 04

Sensor Placement Optimization Method of Visual Sensor Networks based on Multi-objective Constraints

    In order to achieve the purpose of large-scale visual tracking of targets based on Visual Sensor Networks (VSNs), this video demonstrates the experimental results of the proposed sensor placement optimization method to provide a reasonable sensor configuration that satisfies the requirements of maximal network coverage and minimal reconstruction errors as possible. We design an intelligent optimization algorithm that combines the advantages of the Particle Swarm Optimization (PSO) and Genetic Algorithm (GA), avoiding the local optima as much as possible while increasing the optimization speed. Extensive comparison experiments are conducted under different conditions, including different optimization objectives, different approaches, different sampling parameters, and different search methods.   [YouTube] [Youku]

2019 / 12 / 09

Practical Distributed Control for Cooperative VTOL UAVs to Fly Freely

    In this video, a practical distributed control method for cooperative VTOL UAVs to fly freely will be introduced. Drones are now becoming increasingly accessible to amateur and commercial users alike. A safety air traffic management (ATM) system is needed to help ensure this newest entrant into the skies does not collide with buildings, larger aircraft, or one another. Traditionally, the main role of air traffic management (ATM) is to keep a prescribed separation among all aircraft by using centralized control. However, it is infeasible for increasing drones because the traditional control method lacks scalability. In order to address such a problem, free flight is a developing air traffic control method that uses distributed control.   [YouTube] [Youku]

2019 / 06 / 08

Accurate and Flexible Calibration Method for a class of Visual Sensor Networks

    This video demonstrates the experimental results of the proposed calibration method of a class of visual sensor networks. In the proposed visual sensor network, the employed smart cameras are synchronized by an external trigger, and then implement the image processing inside the camera clients. The multi-camera calibration process consists of Intrinsic calibration, extrinsic calibration, and global coordinate determination. A Unity3D-based virtual platform, in which the total number and configurations of cameras, as well as the environment scene, can be arbitrarily edited, is designed to test the calibration algorithm. Extensive experiments based on synthetic and real data are performed to demonstrate the effectiveness of the proposed multi-camera calibration method.   [YouTube] [Youku]

2019 / 05 / 15

A Lifting Wing Fixed on Multirotor UAVs for Long Flight Ranges

    We present a lifting wing fixed on multirotor UAVs to achieve long flight ranges. This video introduces why the lifting wing design works and the effect of the design. And the last part of the video shows the aircraft delivers a package in the condition of Scale 5 wind.   [YouTube] [Youku]

2018 / 11 / 5

Position Control of Tethered Multicopters with Onboard Inertial Sensors

    In practice, tethered multicopter is often used to addressed the problem faced by traditional multicopter which is usually limited by critical factors such as endurance, computing capabilities and safety regulations. However, tethered multicopter usually requires information of DGPS or the tether inclination information for position control. In this paper, a new control strategy is proposed and the relative position of the tethered multicopter can be controlled to the target while keeping the cable taut without DGPS or inclination sensors. Stability analysis of the proposed controller based on Lyapunov function is given. Stimulation and experimental results are provided to show the effectiveness of the proposed control strategy.   [YouTube] [Youku]

2018 / 10 / 21

Indoor Multi-Camera Based Testbed for 3D Tracking and Control of UAVs

    This video presents the design and implementation of an indoor multi-camera based testbed for 3D tracking and control of Unmanned Aerial Vehicles (UAVs). The testbed consists of four major components: a multi-camera system, a ground control system, onboard reflective markers, and target UAVs, which performs image processing, camera calibration, 3D reconstruction, pose estimation, and motion control. Experimental results indicate that the proposed testbed is accurate, efficient, and robust for 3D tracking and control of UAVs, hence making it a promising platform for the verification of advanced guidance, navigation, and control algorithms.   [YouTube] [Youku]

2018 / 8 / 29

Failsafe Mechanism Design for Autonomous Aerial Refueling using State Tree Structure

    The Failsafe Mechanism is designed to prevent dangerous fight maneuvers and command conflicts during autonomous aerial refueling. This video presents the design of the simulation platform of the failsafe mechanism, and the demonstration video of three testing cases.   [YouTube] [Youku]

2018 / 3 / 15

A Reliable Docking Control Scheme for Probe-Drogue Refueling

    This video shows a reliable docking control scheme for probe-drogue refueling. By imitating pilots’ refueling operations, the proposed docking controller can achieve a successful docking quickly, accurately, and safely.   [YouTube] [Youku]

2017 / 12 / 16

An Automatic Safety Testing Platform for UAV Autopilot Systems

    Safety testing is very important for UAV autopilot development. However, the manual experimental testing methods are very costly and inefficient. This video presents a platform based on the Hardware In The Loop (HITL) mode of autopilot with Pixhawk hardware + PX4 software. The autopilot is running with the sensor data generated by a high-fidelity UAV dynamic simulator on a computer.   [PPT] [YouTube] [Youku]

2017 / 10 / 26

Visual-Inertial Estimation of Velocity for Multicopters Based on Vision Motion Constraint

    Velocity estimation is essential for multicopters to guarantee flight stability and maneuverability. This video shows the experimental results of a new visual-inertial estimation of velocity for multicopters based on vision motion constraint in GPS-denied or confined environments.   [YouTube] [Youku]

2017 / 08 / 21

Velocity Estimation Using Monocular Camera Based on Conventional Techniques in Computer Vision

    Estimating the velocity of a Quadcopter in GPS denied environments is one of the key challenges today. We have designed an algorithm to estimate velocity of a Quadcopter using a downward facing camera, IMU and Sonar using conventional image registration techniques. The results are demonstrated in this video for a series of experiments performed in different environments.   [YouTube] [Youku]

2017 / 04 / 09

Robust Pose Estimation for Multirotor UAVs Using Off-board Monocular Vision

    This video shows that Quadrotor indoor hovering could be achieved with only two markers detected by an off-board camera.   [YouTube] [Youku]

2017 / 1 / 16

A Control Performance Index for Multicopters

    People usually want to know whether their multicopters are safe enough to continue the mission or not. In this video, a new control performance index (CPI) is used to monitor the real-time performance of a quadcopter called Qball-X4. Based on the new CPI, a switching control framework is proposed which can deal with the effect of additional payloads, propulsor degradation, unacceptable wind disturbances simultaneously.In order to show the effectiveness of the CPI, different weights are attached to the x axis of the Qball-X4. Real-time safety decision (1 for safe and 0 for unsafe) is made based on the reliable flight control framework.   [YouTube] [Youku]

2016 / 05 / 25

A Semi-Autonomous Multicopter Decision-Making and Virtual Realization by State-Machine

    A Semi-Autonomous Multicopter Decision-Making framework is displayed by State-machine tool in Matlab. The video presents multiple fault patterns and the corresponding failsafe mechanism.   [YouTube] [Youku]

2016 / 04 / 15

A Pesticide Spray Mission Performed by Multi-quadrotors: Simulation Phase

    This video shows a protocol for multiple quadcopters is designed, aiming at complete pesticide spray fully autonomously. In this protocol, collision is avoided for quadcopters; when the battery capacity of a quadcopter is low, the quadcopter will quickly return to base to charge and return to work after fully charging the batteries; the tasks can be reassigned autonomously when a quadcopter fails.   [YouTube] [Youku]

2016 / 02 / 03

The Dynamics of the Drogue with HDU under the Bow Wave in the Docking Stage of the Probe-drogue Air-to-air Refuelling

    This video shows the motion of the drogue in the docking stage of the probe-drogue refueling.Three models are used to generate the motion of the drogue: the hose-drogue model without HDU, the hose-drogue model with HDU under Controller 1 and Controller 2. The comparison shows the motion of the drogue with HDU is closer to the experiment than that without HDU.   [YouTube] [Youku]

2015 / 04 / 20

Additive-State-Decomposition Control for Quadrotors

    We aim to test our robust control method by attaching a payload on the quadrotor.   [YouTube] [Youku]

2015 / 01 / 25

Hexacopter Flight Test with One Rotor Failure

    We aim to test the degraded controller for a hexacopter subject to one rotor failure    [YouTube] [Youku]

2015 / 04 / 14

A Simulation System for Probe-Drogue Aerial Refueling

    We developed a probe-drogue aerial refueling simulation system to research the control strategy under multiple kinds of wind effects, especially the bow wave effect.    [YouTube] [Youku]

2015 / 01 / 25

Rotation angle measurement based on monocular vision

    We aim to measure rotation angles using a camera and a checkboard fixed on the rotation object.    [YouTube] [Youku]

2015 / 01 / 25

Quadrotor hovering with an optical motion capture system

    We aim to achieve Quadrotor indoor hovering by using an optical motion capture system.    [YouTube] [Youku]