• Journal of Institute of Control, Robotics and Systems
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• v.22 no.1
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• pp.24-30
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• 2016

The accuracy of small and low-cost CCD cameras is insufficient to provide data for precisely tracking unmanned aerial vehicles (UAVs). This study shows how a quad rotor UAV can hover on a human targeted tracking object by using data from a CCD camera rather than imprecise GPS data. To realize this, quadcopter UAVs need to recognize their position and posture in known environments as well as unknown environments. Moreover, it is necessary for their localization to occur naturally. It is desirable for UAVs to estimate their position by solving uncertainty for quadcopter UAV hovering, as this is one of the most important problems. In this paper, we describe a method for determining the altitude of a quadcopter UAV using image information of a moving object like a walking human. This method combines the observed position from GPS sensors and the estimated position from images captured by a fixed camera to localize a UAV. Using the a priori known path of a quadcopter UAV in the world coordinates and a perspective camera model, we derive the geometric constraint equations that represent the relation between image frame coordinates for a moving object and the estimated quadcopter UAV's altitude. Since the equations are based on the geometric constraint equation, measurement error may exist all the time. The proposed method utilizes the error between the observed and estimated image coordinates to localize the quadcopter UAV. The Kalman filter scheme is applied for this method. Its performance is verified by a computer simulation and experiments.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.32-37
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• 2015

Unmaned Aerial Vehical(UAV) is a flight which is automatically flying by remote control on th ground. However UAV has an advantage of control that is easy, but has an disadvantage of not hovering. By comparison, quadcopter which is one of the UAV is easily operated. Also quadcopter has hovering function and high stability. In this paper, we propose stable flight algorithm associated PID(proportional-integral-derivative) control with fuzzy contorl to implement stable quadcopter system. After getting a positioning information of the drone, This proposed system is implemented for stable flight through flight attitude control using gyro and acceleration sensor. We also propose the flight mode system to hover drone with GPS sensor.

• Journal of Aerospace System Engineering
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• v.14 no.5
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• pp.9-17
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• 2020

Mobile robots, including UAVs perform missions with limited fuel. Therefore, the energy-aware path planning is required to maximize efficiency when the robot is operated for a long time. In this study, we estimated the power consumption for each maneuver of a quadcopter UAV in the 3D environment and applied to the cost functions of D^⁎ Lite. The simulations were performed in a 3D environment that is similar to the industrial sites. The efficiency of path generation was high when the energy-aware path planning with simplified heuristic was applied. In addition, the energy-aware path was generated 19.3 times faster than the shortest path with a difference within 3.2%.

• The Journal of Korea Robotics Society
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• v.16 no.2
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• pp.155-163
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• 2021

In this paper, we propose a four 2-link robotic leg landing system that is used for leveling the bottom of the landing system, even when the quadcopter posture is changed. The case of conventional skid type landing gear has a risk when the quadcopter lands on a moving vehicle because the skid type landing gear is tilted to the landing site at this situation. To solve this problem, it is necessary to level the bottom of the landing system when the quadcopter posture is changed in the flight. Therefore, the proposed landing system used a four 2-link robotic leg with leveling method. The leveling method was derived from the method of determining a plane. The superiority of the proposed system was verified with 6-axis stewart platform and real flight experiment, and it shows feasibility of leveling method and proposed landing system.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.263-270
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• 2020

In this paper, In this paper, we describe the UAV system using image processing for autonomous quadcopters, where they can apply logistics, rescue work etc. we propose high-speed hovering height and posture control method based on state feedback control with CNN from camera because we can get image of the information only every 30ms. Finally, we show the advantages of proposed method by simulations and experiments.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.1
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• pp.19-26
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• 2017

In this paper, we describe the design and performance of UAV system toward compact and fully autonomous quadrotors, where they can complete logistics application, rescue work, inspection tour and remote sensing without external assistance systems like ground station computers, high-performance wireless communication devices or motion capture system. we propose high-speed hovering flyght height control method based on state feedback control with image information from active camera and multirate observer because we can get image of the information only every 30ms. Finally, we show the advantages of proposed method by simulations and experiments.

• The Journal of Korea Robotics Society
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• v.17 no.4
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• pp.438-446
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• 2022

In this paper, we propose an intelligent three-legged landing system that can maintain stability and level even on rough terrain than conventional four-legged landing systems. Conventional landing gear has the limitation that it requires flat terrain for landing. The 3-leg landing system proposed in this paper extends the usable range of the legs and reduces the weight, allowing the quadcopter to operate in various environments. To do this, kinematics determine the joint angles and coordinates of the legs of the two-link structure. Based on the angle value of the quadcopter detected via the IMU sensor, the leg control method that corrects the posture is determined. A force sensor attached to the end of the leg is used to detect contact with the ground. At the moment of contact with the ground, landing control starts according to the value of the IMU sensor. The proposed system verifies its reliability in various environments through an indoor landing test stand. Finally, in an outdoor environment, the quadcopter lands on a 20 degree incline and 20 cm rough terrain after flight. This demonstrates the stability and effectiveness of the 3-leg landing system even on rough terrain compared to the 4-leg landing system.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.3
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• pp.225-232
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• 2014

In this study, a cooperative UAV and UGV platform is proposed to obtain a wide range of visual information. The UAV recognizes a pattern marker on UGV and tracks the UGV without user control. It can provide wide range of visual information for a user in the UGV. The UGV by a user is controled equipped with an aluminum board. And the UAV can take off and land on the UGV. The UAV uses two cameras; one camera is used to recognize a pattern marker and another is used to provide a wide range of visual information to the UGV's user. It is guaranteed that the proposed visual-based approach detects and tracks the target marker on the UGV, and then lands well. The experimental results show that the proposed approach can effectively construct a cooperative UAV/UGV platform for obtaining a wide range of vision information.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.1
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• pp.39-48
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• 2022

In this paper, we propose an anomaly detection system (ADS) to detect anomalies of the in-vehicle network for unmanned aerial vehicle (UAV). The proposed ADS detects the anomalies by measuring the similarity of status messages sequences periodically sent by the UAV to the ground control system. We defined three types of malicious message injection attacks that can be performed on the in-vehicle network of UAV and simulated those attack techniques in the Pixhawk4 quadcopter. The proposed ADS can detect abnormal sequences with accuracy of higher than 96%.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.5
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• pp.444-450
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• 2015

The accuracy of small and low cost CCD camera is insufficient to provide data for precisely tracking unmanned aerial vehicles(UAVs). This study shows how UAV can hover on a human targeted tracking object by using CCD camera rather than imprecise GPS data. To realize this, UAVs need to recognize their attitude and position in known environment as well as unknown environment. Moreover, it is necessary for their localization to occur naturally. It is desirable for an UAV to estimate of his attitude by environment recognition for UAV hovering, as one of the best important problems. In this paper, we describe a method for the attitude of an UAV using image information of a maker on the floor. This method combines the observed position from GPS sensors and the estimated attitude from the images captured by a fixed camera to estimate an UAV. Using the a priori known path of an UAV in the world coordinates and a perspective camera model, we derive the geometric constraint equations which represent the relation between image frame coordinates for a marker on the floor and the estimated UAV's attitude. Since the equations are based on the estimated position, the measurement error may exist all the time. The proposed method utilizes the error between the observed and estimated image coordinates to localize the UAV. The Kalman filter scheme is applied for this method. its performance is verified by the image processing results and the experiment.