Real-Time Visual Feedback Control of Multi-Camera UAV

Recently, flight control of unmanned aerial vehicles (UAVs) in non-global positioning system (GPS) environments has become increasingly important. In such an environment, visual sensors are important, and their main roles are self-localization and obstacle avoidance. In this paper, the concept of a multi-camera UAV system with multiple cameras attached to the body is proposed to realize high-precision omnidirectional visual recognition, self-localization, and obstacle avoidance simultaneously, and a two-camera UAV is developed as a prototype. The proposed flight control system can switch between visual servoing (VS) for collision avoidance and visual odometry (VO) for self-localization. The feasibility of the proposed control system was verified by conducting flight experiments with the insertion of obstacles.

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ACT/FHS System Identification Including Rotor and Engine Dynamics

Journal of the American Helicopter Society ◽

10.4050/jahs.64.022003 ◽

2019 ◽

Vol 64 (2) ◽

pp. 1-12

Author(s):

Susanne Seher-Weiß

Keyword(s):

Control System ◽

System Identification ◽

Flight Control ◽

The Body ◽

Likelihood Method ◽

Flight Control System ◽

Transmission Zeros ◽

Model Following ◽

Systems Models ◽

German Aerospace

At the German Aerospace Center (DLR) Institute of Flight Systems, models of the Active Control Technology/Flying Helicopter Simulator (ACT/FHS), an EC135 with a fly-by-wire/light flight control system, are needed for control law development and simulation. Thus, models are sought that cover the whole flight envelope and are valid over a broad range of frequencies. Furthermore, if the models are to be used in the feedforward loop of the model following the control system, they have to be invertible and thus should not have any positive transmission zeros. For rotor flapping, the explicit formulation with flapping angles was modified slightly to avoid positive transmission zeros. For the regressive lead–lag, a simple model formulation was found that needs only one dipole with two states. The engine dynamics were first modeled separately and then coupled to the body/rotor model. The final integrated model has 17 states and yields a good match for frequencies up to 30 rad/s. All system identification was performed using the maximum likelihood method in the frequency domain.

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DESIGN AND CONTROL SYSTEM OF THE ROBOT ORNITHOPTER, EQUIPPED WITH WINGS AND TAIL

Proceedings of Southwest State University ◽

10.21869/2223-1560-2018-22-2-18-26 ◽

2018 ◽

Vol 22 (2) ◽

pp. 18-26 ◽

Cited By ~ 1

Author(s):

S. F. Jatsun ◽

О. G. Loktionova ◽

L. Yu. Vorochaeva ◽

О. V. Emelianova

Keyword(s):

Control System ◽

Flight Control ◽

Control Unit ◽

Longitudinal Axis ◽

Control Device ◽

Control Area ◽

The Body ◽

Flight Control System ◽

Spherical Hinge ◽

And Control

The paper deals with the ornithopter flight which simulates the flight of a bird. The robot consists of a body, two folding wings and a tail. The ornithopter roll is provided by wing swings, and pitch and yaw are provided by twists of the tail in two planes. When switching to the design scheme of the device, each wing is replaced by two links connected to each other and to the body by means of cylindrical hinges, the axes of all hinges are parallel to the longitudinal axis of the robot. Two mechanisms are used to implement swings in the device. One of them (the mechanism of swings) directly provides fluctuations in the wings relative to the body, as well as changing their area by adding when moving up and decomposition when moving down. This mechanism consists of a motor and crank-rod-rocker mechanism. The second mechanism (rotation of the ailerons on the wings) allows the wings in addition to flapping additionally to flex during motion, thereby "pocketing" of the air and the extra control area of the wings: its decrease with the movement of the wings up and the increase in the movement of the wings down. The tail is connected to the body due to the spherical hinge and two crank mechanisms. With the help of one of the mechanisms the tail rotates relative to the longitudinal axis of the body in the horizontal plane, and with the help of the other - in the vertical. For this robot a flight control system is proposed, which provides the robot movement along a given trajectory. The control system includes a control unit and a control device (ornithopter). The control unit is formed by modules specifying the effects and calculation of angles, as well as comparator and controller. The control device includes drives, links (wings and tail) and the robot body. Management is carried out on six generalized coordinates determining the position and orientation of the hull in space. For this purpose, eight feedbacks are used in the angles of rotation of the wings and the tail of the robot relative to its body.

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