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This paper addresses the particle filters to deal with the measurement ambiguity. In terrain referenced navigation, the ambiguous measurement update due to the similar terrain profiles causes the performance degradation and it can be the primary reason of divergence in the worst case. We proposed a method to cope with terrain ambiguity that utilizes a solution to the out-of-sequence measurement(OOSM)...
Under GPS-denied conditions, an inertial navigation diverges easily due to integration drift in the measurement of acceleration and angular velocity. Therefore, a terrain relative navigation (TRN) is applied to correct the drift error for precise lunar landing mission. Diverse sensors are used for the TRN in these days, such as a Light and Detection and Ranging (LIDAR), laser altimeter, and optical...
In this paper, the hybrid fuzzy-PID controller for a coaxial rotor helicopter is developed as a supplement to the conventional PID controller. The coaxial rotor helicopter uses one motor and two swash plates linked to each other. The helicopter system is modeled by nonlinear dynamics. The PID control system works well with a moderate velocity change. However, it provides unsatisfactory performance...
A decentralized controller for target tracking and obstacle avoidance for a multi-agent system is proposed. The controller is based on a navigation function which is composed of a goal function, as the D-optimality criterion of the Fisher information matrix, and a constraint function, which generates repulsive force to the agents near the obstacle. The multi-agent system is modeled as a graph and...
This paper proposed a framework for airborne multisensor management for multitarget tracking, considering each of multiple unmanned aircraft as a sensor. The purpose of the algorithm is to quantify the performance of the multitarget tracking and to determine the time and location of the sensor deployment. Utilizing the posterior Cramer-Rao lower bound, the inverse of the Fisher information matrix,...
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...
This paper investigates terrain referenced navigation (TRN) system integrated with inertial navigation system (INS). TRN system estimates navigation information of an aircraft by using a terrain elevation database and radar altimeter measurements. We derive 15-state strapdown INS error kinematics equations to design fusion algorithm. A point mass filter (PMF) based on Bayesian estimation is applied...
A vision-only navigation system is addressed for autonomous navigation of unmanned aerial vehicles (UAVs) with monocular camera as the only sensor. Typical vision-based navigation algorithms blend inertial navigation data with vision measurements and other available information to estimate vehicle's position. In this paper, however, we propose an approach that replaces the high-cost inertial navigation...
Hemispherical resonator gyroscope is one of the vibratory gyroscopes that can work as an angle sensor as well as an angular rate sensor. Vibratory gyroscopes have advantages that it has relatively long operation time since it has no moving part, it has relatively larger measurement range, and so on. These types of gyros are based on the principle of Coriolis effect. To operate the vibratory gyros,...
This paper studies a terrain referenced navigation which estimates a status of aircraft by using terrain elevation database and radar altimeter measurements. Terrain referenced navigation algorithm usually divides into two modes which are acquisition mode and tracking mode. In the tracking mode, states are estimated in real-time and extended Kalman filter(EKF) is a well-known navigation method for...
This paper concerns with the autonomous flight control system of an unmanned helicopter. We adopt a model-free discrete linear quadratic regulation (LQR) architecture based on reinforcement learning algorithm by rewriting the Q-learning approach. From input and output data, the linear quadratic optimal gain is directly found without system identification procedure. Least square method is adopted in...
This paper presents target motion estimation for multiple air vehicles. The motion of the airborne target is estimated by vision information from camera sensors fixed to the followers. Each camera sensors provides information of the target by three angles: an azimuth angle, an elevation angle, and a subtended angle. In the frame work of information filter, each follower estimates position, velocity...
Nowadays, Earth observation satellites are widely used to acquire high quality, and the satellites should have more observation missions at the same time. In this case, it is useful to develop a systematic command generation method for satellite pointing to acquire wide area image efficiently. In this paper, three efficient methods are proposed to operate Earth observation satellite attitude pointing...
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