| 1. |
- Adaldo, Antonio, et al.
(författare)
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Cooperative coverage for surveillance of 3D structures
- 2017
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Ingår i: IEEE International Conference on Intelligent Robots and Systems. - Piscataway, NJ : Institute of Electrical and Electronics Engineers (IEEE). - 9781538626825 ; , s. 1838-1845
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Konferensbidrag (refereegranskat)abstract
- In this article, we propose a planning algorithm for coverage of complex structures with a network of robotic sensing agents, with multi-robot surveillance missions as our main motivating application. The sensors are deployed to monitor the external surface of a 3D structure. The algorithm controls the motion of each sensor so that a measure of the collective coverage attained by the network is nondecreasing, while the sensors converge to an equilibrium configuration. A modified version of the algorithm is also provided to introduce collision avoidance properties. The effectiveness of the algorithm is demonstrated in a simulation and validated experimentally by executing the planned paths on an aerial robot.
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| 2. |
- Alexhs, Kostas, et al.
(författare)
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Autonomous quadrotor position and attitude PID/PIDD control in GPS-denied environments
- 2011
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Ingår i: International Review of Automatic Control. - 1974-6059 .- 1974-6067. ; 4:3
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Tidskriftsartikel (refereegranskat)abstract
- This article addresses the control problem of an unmanned quadrotor in the absence of absolute position measurement data (e.g. GPS, external cameras). Based on an attached Inertia Measurement Unit, a sonar and an optic flow sensor, the quadrotor’s translational and rotational motion-vector is estimated using sensor fusion algorithms. A control scheme consisted of three Proportional-Integral-Derivative (PID) controllers for the translational motions, combined with three Proportional-Integral-Derivative-second Derivative (PIDD) controllers for the attitude dynamics is utilized in order to achieve accurate position hold and attitude tracking. The controller is implemented on a quadrotor prototype in indoor position hold experiments and aggressive attitude regulation maneuvers.
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| 3. |
- Alexis, Kostas, et al.
(författare)
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Experimental Constrained Optimal Attitude Control of a Quadrotor subject to Wind Disturbances
- 2014
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Ingår i: International Journal of Control, Automation and Systems. - : Springer Science and Business Media LLC. - 1598-6446 .- 2005-4092. ; 12:6, s. 1289-1302
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Tidskriftsartikel (refereegranskat)abstract
- The design and experimental verification of a Constrained Finite Time Optimal Controller (CFTOC) for attitude maneuvers of an Unmanned Quadrotor operating under severe wind conditions is the subject of this article. The quadrotor’s nonlinear dynamics are linearized in various operating points resulting in a set of piecewise affine models. The CFTO–controller is designed for set-point maneuvers taking into account the switching between the linear models and the state and actuation constraints. The control scheme is applied on experimental studies on a prototype quadrotor operating both in absence and under presence of forcible atmospheric disturbances. Extended experimental results indicate that the proposed control approach attenuates the effects of induced wind–gusts while performing accurate attitude set–point maneuvers.
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| 4. |
- Alexis, Kostas, et al.
(författare)
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Model predictive quadrotor control: attitude, altitude and position experimental studies
- 2012
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Ingår i: IET Control Theory & Applications. - : Institution of Engineering and Technology (IET). - 1751-8644 .- 1751-8652. ; 6:12, s. 1812-1827
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Tidskriftsartikel (refereegranskat)abstract
- This article addresses the control problem of an unmanned quadrotor in an indoor environment where there is lack of absolute localization 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 achieve precise trajectory control, under the presence of forcible wind–gusts. The quadrotor’s attitude, altitude and horizontal linearized dynamics result in a set of Piecewise Affine models, enabling the controller to account for a larger part of the quadrotor’s flight envelope while modeling the effects of atmospheric disturbances as additive–affine terms in the system. The proposed controller algorithm accounts for the state and actuation constraints of the system. The controller is implemented on a quadrotor prototype in indoor position tracking, hovering and attitude maneuvers experiments. The experimental results indicate the overall system’s efficiency in position/altitude/attitude set–point maneuvers.
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| 5. |
- Alexis, Kostas, et al.
(författare)
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Model predictive quadrotor indoor position control
- 2011
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Ingår i: 19th Mediterranean Conference on Control & Automation (MED 2011). - Piscataway, NJ : IEEE Communications Society.
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Konferensbidrag (refereegranskat)abstract
- 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 yaw (RPY) angles, the angular rates and the translational accelerations a switching Model Predictive Controller is designed. The quadrotor dynamics is linearized at various operating points according to the angular rates and the RP angles. The switching is inferred according to the various linearized models of the quadrotor. The controller is applied on a quadrotor prototype in low-altitude position hold maneuvers at very constrained environments. The experimental results indicate the overall system’s efficiency in position/altitude set–point maneuvers.
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| 6. |
- Alexis, Kostas, et al.
(författare)
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On trajectory tracking model predictive control of an unmanned quadrotor helicopter subject to aerodynamic disturbances
- 2014
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Ingår i: Asian Journal of Control. - : Wiley. - 1561-8625 .- 1934-6093. ; 16:1, s. 209-224
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Tidskriftsartikel (refereegranskat)abstract
- In this article a Model Predictive Control (MPC) strategy for the trajectory tracking of an unmanned quadrotor helicopter is presented. The quadrotor’s dynamics are modeled by a set of Piecewise Affine (PWA) systems around different operating points of the translational and rotational motions. The proposed control scheme is dual and is consisted by an integral MPC for the translational motions, followed by a MPC–scheme for the quadrotor’sattitude motions’ tracking. By the utilization of PWA representations, the controller is computed for a larger part of the quadrotor’s flight envelope. Theproposed dual control scheme is able to calculate optimal control actions with robustness against atmospheric disturbances (e.g. wind gusts) and physical constraints of the quadrotor (e.g. maximum lifting forces or fixed thrust limitations in order to extend flight endurance). Extended simulation studies prove the efficiency of the MPC–scheme, both in trajectory tracking and aerodynamic disturbances attenuation.
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| 7. |
- Alexis, Kostas, et al.
(författare)
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Switching model predictive attitude control for a quadrotor helicopter subject to atmospheric disturbances
- 2011
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661 .- 1873-6939. ; 19:10, s. 1195-1207
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Tidskriftsartikel (refereegranskat)abstract
- In this article a Switching Model Predictive Attitude Controller for an Unmanned quadrotor Helicopter subject to atmospheric disturbances is presented. The proposed control scheme is computed based on a Piecewise Affine (PWA) model of the quadrotor’s attitude dynamics, where the effects of the atmospheric turbulence are taken into consideration as additive disturbances. The switchings among the PWA models are ruled by the rate of the rotation angles and for each PWA system a corresponding model predictive controller is computed. The suggested algorithm is verified in experimental studies in the execution of sudden maneuvers subject to forcible wind disturbances. The quadrotor rejects the induced wind–disturbances while performing accurate attitude tracking.
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| 8. |
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| 9. |
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| 10. |
- Andrikopoulos, Georgios, et al.
(författare)
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A Survey on applications of pneumatic artificial muscles
- 2011
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Ingår i: 19th Mediterranean Conference on Control and Automation, MED 2011. - Piscataway, NJ : IEEE Communications Society. - 9781457701252 ; , s. 1439-1446
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Konferensbidrag (refereegranskat)abstract
- The aim of this article is to present a survey on applications of Pneumatic Artificial Muscles (PAMs). PAMs are highly non–linear pneumatic actuators where their elongation is proportional to the interval pressure. During the last decade, there has been a significant increase in the industrial and scientific utilization of PAMs due to their advantages such as high strength and small weight, while various types of PAMs with different technical characteristics have been appeared in the relative scientific literature. This article will summarize the key enabling applications in PAMs that are focusing in the following areas: a) Biorobotic, b) Medical, c) Industrial, and d) Aerospace applications
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