1 / 22

Design of controllers for a quad-rotor UAV using optical flow

Design of controllers for a quad-rotor UAV using optical flow. Bruno Hérissé CEA List Fontenay-Aux-Roses, France bruno.herisse@cea.fr. Introduction. Purpose : measurements of inertial data and visual optical flow for the design of controllers for a VTOL UAV. IMU

kato-witt
Download Presentation

Design of controllers for a quad-rotor UAV using optical flow

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Design of controllers for a quad-rotor UAV using optical flow Bruno Hérissé CEA List Fontenay-Aux-Roses, France bruno.herisse@cea.fr LIST – DTSI

  2. Introduction • Purpose : measurements of inertial data and visual optical flow for the design of controllers for a VTOL UAV. IMU (inertial measurments unit) Camera SRI-LIST

  3. T F=f(T,R) Translational dynamics Constant forces  Rotational Dynamics Already controlled Model of the UAV • The system is nonlinear and under actuated. • Definition of used frames. • I : Inertial frame attached to the earth • B: body-fixed frame attached to the vehicle’s center of mass. • Vehicle state: • : position of the center of mass in I • : speed of the center of mass in I • : orientation matrix from B to I • : rotational velocity in B • Inputs: • : Global thrust in B • :Control torque in B • Dynamic Model used : High gain controller SRI-LIST

  4. Plan • The main object : elaboration of controllers for hovering flight, vertical landing and terrain following of a VTOL UAV above a textured target. • Optical flow computation • Computation of the translational optical flow • A non-linear controller for the stabilization of the hovering flight. • A non-linear controller for a smooth vertical landing. • A non-linear controller for terrain following. SRI-LIST

  5. Kinematics of an image point under spherical projection • Optical flow from an image plane to a spherical retina. Optical Flow SRI-LIST

  6. T  d I Translational optical flow computation Known data : η Measured data : ,  Translational term Rotational term SRI-LIST

  7. + - Schema of control Perturbations Set point : wc State : (ξ , v) Controller UAV dynamics (P, PI) (0 ou ω*) Camera Optical flow : w Environment configuration SRI-LIST

  8. Stabilization of the hovering flight • For the stabilisation of the hovering flight define the error term, • The goal is the regulation of to zero : • The control law ensures the exponential convergence of to zero (PI-type controller) • The UAV does not collide the obstacle SRI-LIST

  9. Vertical landing control (1) • Consider that , that is is the distance of the vehicle to the ground • Define for the control of the third component of the dynamics the error term, • Goal: and for all time • Proposition 1: Consider the control law , then for all , one can ensure the exponential convergence of to zero while keeping for all time. Smooth vertical landing SRI-LIST

  10. Vertical landing control (2) • Proof: • Define , and , and • The third component of the dynamics is: Integrating this equation, it yields • Differentiating L, it yields • Chosing klim such that and It ensures that is bounded. Consequently, converges to zero with as exponential decay constant. SRI-LIST

  11. Vertical landing control (3) • Proposition 2: Consider the following control law, then for all it ensures the exponential convergence of to zero with as exponential decay constant while keeping for all time. SRI-LIST

  12. Drone: - Embeded attitude control from IMU data -running at 166Hz Camera: -Focus: 2.1mm Numerical transmission: - Transmision of the desired attitude to the drone - Transmission of IMU data to the ground station - 70 ms are required for the data transmission • Analogical transmission: • Transmission at 2.4GHz • Associate with an acquisition card, a new image is available each 50 ms Ground station: Treatment of vision algorithms at 60 ms Textured ground Experimental setup SRI-LIST

  13. Experiments SRI-LIST

  14. Terrain following (1) • Consider that • The goal is , or has to be set to a constant : • Control on the z axis and on the x axis • Control on the x axis and on the z axis • Maintaining a constant forward thrust, the drag force opposite to the vehicle's direction of flight ensures that the forward velocity converges to a constant. Then, one can consider that is constant. SRI-LIST

  15. Terrain following (2) • The control law ensures the asymptotic convergence of to • The UAV does not collide the obstacle SRI-LIST

  16. Terrain following (3) • Proof: SRI-LIST

  17. Terrain following (3) SRI-LIST

  18. Terrain following (3) SRI-LIST

  19. Experiments SRI-LIST

  20. Conclusion • Computation of the translational optical flow over a textured flat target plane. • Rigorous non-linear controllers for hovering flight, vertical landing and terrain (or wall) following. • The UAV remains free from collision. • The control approach has been experimented on a quad-rotor UAV to demonstrate the performance of controllers. SRI-LIST

  21. Publications [1] Herisse, B.; Russotto, F-X.; Hamel, T. & Mahony, R. Hovering flight and vertical landing control of a VTOL Unmanned Aerial Vehicle using Optical FlowIEEE/RSJ International Conference on Intelligent Robots and Systems, IROS'08, 2008 [2] Herisse, B.; Hamel, T.; Mahony, R. & Russotto, F-X. A nonlinear terrain-following controller for a VTOL Unmanned Aerial Vehicle using translational optical flowIEEE International Conference on Robotics and Automation, ICRA'09, 2009 François-Xavier Russotto Tarek Hamel Robert Mahony SRI-LIST

  22. Acknowledgments Projet Naviflow Assistance à la NAVIgation par FLux Optique SRI-LIST

More Related