Kostas Alexis

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This paper presents a novel path planning algorithm for the autonomous exploration of unknown space using aerial robotic platforms. The proposed planner employs a receding horizon “next-best-view” scheme: In an online computed random tree it finds the best branch, the quality of which is determined by the amount of unmapped space that can be(More)
Within this paper, a new fast algorithm that provides efficient solutions to the problem of inspection path planning for complex 3D structures is presented. The algorithm assumes a triangular mesh representation of the structure and employs an alternating two-step optimization paradigm to find good viewpoints that together provide full coverage and a(More)
The design process, development considerations as well as hover modeling and control of a high-end capability unmanned Tri-TiltRotor aerial vehicle are the subjects of this article. Tilt-Rotor UAVs efficiently perform as fixed-wing air-craft and as rotorcrafts, being capable of both high-endurance high-speed flight as well as of vertical take-off and(More)
This study addresses the control problem of an unmanned quadrotor in an indoor environment where there is lack of absolute localisation data. Based on an attached inertia measurement unit, a sonar and an optic-flow sensor, the state vector is estimated using sensor fusion algorithms. A novel switching model predictive controller is designed in order to(More)
The challenge of aerial robotic physical interaction towards inspection of infrastructure facilities through contact is the main motivation of this paper. A hybrid model predictive control framework is proposed, based on which a typical quadrotor vehicle becomes capable of stable physical interaction, accurate trajectory tracking on environmental surfaces(More)
This article addresses the control problem of quadrotors in environments where absolute-localization data (GPS, positioning from external cameras) is inadequate. Based on an attached IMU and an optical flow sensor the quadrotor's translational velocity is estimated using an Extended Kalman Filter. Subject to the velocity measurements, the roll, pitch and(More)
The experimental translational hovering control of a Tri-TiltRotor Unmanned Aerial Vehicle is the subject of this paper. This novel UAV is developed to possess the capability to perform autonomous conversion between the Vertical Take-Off and Landing, and the Fixed-Wing flight modes. Via this design's implemented features however, the capability for(More)
The design and experimental control of an unmanned Tilt-Rotor aerial vehicle operating in Bi-Rotor mode is presented in this article. Tilt-Rotor UAVs exhibit important flight characteristics due to their ability to fly both like a rotorcraft (in Bi-Rotor Mode) and like a fixed-wing aerial system. The ability of having a dual flight envelope makes ideal for(More)
Abstract—This paper focuses on the problem of robust control of unmanned rotorcrafts against external disturbances, towards achieving their efficient and safe utilization in real– life challenging applications. Relying on state space representations that incorporate the effects of external disturbances and may be applied in most rotorcraft configurations,(More)