2021 / 08 / 18

Practical Control for Multicopters to Avoid Non-Cooperative Moving Obstacles

 Unmanned Aerial Vehicles (UAVs) are now becoming increasingly accessible to amateur and commercial users alike. The main task for UAVs is to keep a prescribed separation with obstacles in the air. In this paper, a collision-avoidance control method for non-cooperative moving obstacles is proposed for a multicopter with the altitude hold mode by using a Lyapunov-like barrier function. Lyapunov-like functions are designed elaborately, based on which formal analysis and proofs of the proposed control are made to show that the collision-avoidance control problem can be solved if the moving obstacle is slower than the multicopter. The result can be extended to some cases of multiple obstacles.What is more, by the proposed control, a multicopter can keep away from obstacles as soon as possible once obstacles enter into the safety area of the multicopter accidentally and converge to the waypoint. Simulations and experiments are given to show the effectiveness of the proposed method by showing the distance from UAV to waypoint and obstacles.   [YouTube] [Youku]

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] [YouTube]

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] [YouTube]

February 3, 2016

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 dockingstage 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] [YouTube]

June 04, 2015

Robust Pose Estimation for Multirotor UAVs Based on Ground Monocular Vision

    We aim to estimate the pose of multirotor UAVs with ground monocular vision.   [YouTube] [YouTube]

April 30, 2015

Additive-State-Decomposition Control for Quadrotors

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

January 25, 2015

Hexacopter Flight Test with One Rotor Failure

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

April 14, 2015

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] [YouTube]

January 25, 2015

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] [YouTube]

January 25, 2015

Quadrotor hovering with an optical motion capture system

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