Wooyoung Jung

SNAIL: an IP-based wireless sensor network approach to the internet of things

Recent technological progress has been materializing the Internet of Things (IoT), which is breathing new computational and communicational capability into anything in everyday life. An important step toward the IoT would be to facilitate suitable wireless sensor network technologies based on a verified standard protocol, the Internet Protocol, to support the network of things. An increase in research efforts has led to maturity in this field, yet there seem to be gaps to be filled because of the focus on how to adapt the IP to the space of things. This article introduces the Sensor Networks for an All-IP World (SNAIL) approach to the IoT. The proposed architecture includes a complete IP adaptation method. It also includes four significant network protocols: mobility, web enablement, time synchronization, and security. The feasibility and interoperability of the proposed approach is confirmed by the implementation of SNAIL platforms and tests on a testbed built in the Korea Advanced Research Network.

SSL-Based Lightweight Security of IP-Based Wireless Sensor Networks

IP-based wireless sensor networks (IP-WSN) are popularly recognized as a global sensor networks infrastructure by combining IPv6 technology with wireless sensor networks (WSN). However, IP-WSN, currently, does not provide security because it is commonly recognized that it is a big burden for IP-WSN to adapt Internets dominant security protocol. We suggest a security protocol for IP-WSN based on Secure Sockets Layer (SSL). We have developed IP-WSN sensor node hardware with 16-bit MSP430 MCU including 116 KB Flash and 8 KB RAM, and implemented IP-WSN software stack and lightweight SSL components. The resource consumption is around 64 KB of Flash and 7 KB of RAM when it is used that ECC for key-exchange and authentication, RC4 for data encryption, and MD5 for hashing. And it takes total 2 s for a full SSL handshake and a 127 bytes packet transfer. It can make IP-WSN secure and be used for the public and private services such as military observation, healthcare, and home-network.

Visual Target Tracking and Relative Navigation for Unmanned Aerial Vehicles in a GPS-Denied Environment

We present a system for the real-time visual relative navigation of a fixed-wing unmanned aerial vehicle in a GPS-denied environment. An extended Kalman filter is used to construct a vision-aided navigation system by fusing the image processing results with barometer and inertial sensor measurements. Using a mean-shift object tracking algorithm, an onboard vision system provides pixel measurements to the navigation filter. The filter is slightly modified to deal with delayed measurements from the vision system. The image processing algorithm and the navigation filter are verified by flight tests. The results show that the proposed aerial system is able to maintain circling around a target without using GPS data.

Unmanned Aircraft Vector Field Path Following with Arrival Angle Control

This paper focuses on unmanned aircraft guidance laws for a straight path and a circular orbit following using the vector field approach. The vector fields introduced in this paper can be applied to not only path following, but also other purposes such as arrival position, angle, and time control. Therefore, they could be applied to various missions providing advantages over other previous vector fields. Stability and performance of the path following has been proved and analyzed using the classical control theory. Simulation using a six degrees-of-freedom aircraft model shows that these guidance laws are effective for the missions even under the existence of wind disturbance. Furthermore, flight experiments with a blended-wing-body type unmanned aircraft are performed to evaluate the proposed vector field guidance algorithm.

Vector field guidance for path following and arrival angle control

This paper focuses on unmanned aircraft guidance laws for a straight path and a circular orbit following using the vector field approach. The vector fields introduced in this paper can be applied to not only path following, but also other purposes such as arrival position, angle, and time control. Therefore, they could be applied to various missions providing advantages over other previous vector fields. Stability and performance of the path following has been proved and analyzed using the classical control theory. And simulation using a six degrees-of-freedom aircraft model shows that these guidance laws are effective for the missions even under the existence of wind disturbance.

Development of multiple unmanned aircraft system and flight experiment

This paper presents results of developing and operating a team of multiple unmanned aircraft system. It is a challenging task since the system complexity increases as the number of the unmanned aircraft increases. Given the autonomy of each vehicle in navigation, guidance, control, and vision-based missions, a system of multiple unmanned aircraft is constructed which is expected to be applied to complicated missions. This paper addresses two essential technologies for automation of such a system: inter-vehicle communication and ground control system. The vehicles can conduct missions by sharing information via inter-vehicle communication without intervention of ground stations. The ground control system is designed to improve situation awareness of the operator managing multiple vehicles. The multiple unmanned aircraft system is verified through flight experiments where the flight scenario is modeled as suppression of enemy air defenses (SEAD) mission, which consists of multisensory target tracking and coordinated formation flying.

Target state estimation for vision-based landing on a moving ground target

This paper describes vision-based target state estimation approaches for autonomous landing on a moving ground target. The state of moving ground target is estimated by using vision information from a gimbaled camera on an Unmanned Aerial Vehicle (UAV). Using the information from vision system, the UAV estimates the state of a moving target on the ground using the Unscented Kalman Filter (UKF). In this paper, three types of process model are compared by numerical simulations: state in inertial frame, state in inertial frame with position uncertainty of UAV, and relative state with acceleration of UAV.

Real-time path planning to dispatch a mobile sensor into an operational area

Abstract This paper addresses problems of large planning time and cost uncertainty for informative path planning of a mobile sensor where the location of sensor deployment is different of that of an operational area. The first problem is that the cost has no term dependent on sensor state before arriving at the operational area and it causes large planning time. The information of the state of interest dissipates over time during the planning time and it degrades performance of sensing operation. The other problem is that the cost is dependent on the parameters to be estimated. To assess the cost, the target state in the future should be predicted by integrating the system model based on noisy initial estimate. The limitation of the informative path planning has a greater impact on performance in this specific problem. A strategy to cope with these problems is to devise a real-time path planning algorithm by using online optimization. The proposed algorithm is divided into two phases; determining the path to the boundary of the operational area and guiding the sensor by an informative potential field in the area. Detailed analysis on performance of the proposed algorithm compared to an optimal solution by nonlinear programming is given. The simulation results have demonstrated that the proposed algorithm can cope with performance degradation observed in the optimal solution.

Experimental Validation of Multiple UAVs with Vector Field Guidance for SEAD(Suppression of Enemy Air Defense)

ABSTRACT In modern warfare, the importance of SEAD(Suppression of Enemy Air Defense) mission is being emphasized. However, this mission runs the risk of hull damage or casualties of our friendly air forces. Because of these risks, research on th e way of minimizing damages and enhancing mission capability is under active discussion. As a part of this research, SEAD mission planning with multiple UAVs has been covered using vector field guidance. This guidance method not only applies to various forms of flight path but also requires less computational power than other guidance methods. Therefore , in this paper, planning methods of SEAD mission for multiple UAVs using vector field guidance and experimental data from flight experiments regarding designed mission has been covered. 초 록 현대전에서 적 방공망 제압 임무는 과거에 비해 그 중요성이 점차 부각되고 있다. 그러나 본 임무는 적의 방공망에 아군의 항공기와 조종사가 노출되는 위험을 안고 있어, 아군의 피해를 최소화하면서 효과적으로 임무를 수행할 수 있도록 하는 연구가 활발히 진행되고 있다. 본 논문에서는 이러한 연구의 일환으로써, 벡터필드 유도기법을 이용하여, 다수 무인기의 적 방공망 제압 임무를 설계하였다. 벡터필드 유도기법은 다른 유도기법들에 비하여 계산 량이 적고 쉽게 응용이 가능한 이점이 있어, 다수 무인기 운용에 해당 기법을 적용하는 경우 무인기간의 상호 협동을 통한 다양한 형태의 임무를 계획할 수 있다. 따라서 벡터필드 유도기법을 이용한 다수 무인기의 적 방공망 제압 임무의 설계방법을 제시함과 동시에, 비행실험을 통하여 그 운용 가능성을 확인해 보았다. Key Words : Multiple UAV`s (다수 무인기), Unmanned Aerial Vehicle, Unmanned Aircraft (무인항공기), Guidance (유도기법), Vector Field (벡터 필드), Suppression of Enemy Air Defence (적 방공망 제압)