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MAE 598 – Special Topics Micro Air Vehicles Lecture 2 Dr. Armando Rodriguez, Professor Department of Electrical Engineering Fulton School of Engineering Arizona State University Tempe, AZ http://www.eas.asu.edu/∼aar/ [email protected] Contributors Michael Thompson, Graduate Student, School of Engineering Matter, Transport, and Energy, AIAA member John S Burnett, Graduate Research Engineer-Vehicle designer Ivan Ramirez, Undergraduate Student, School of Civil, Environmental and Sustainable Engineering, Deyzi Ixtabalan, Undergraduate Student, School of Engineering Matter, Transport, and Energy, AIAA member Outline Motivation State of The Art: Prior and Current Efforts Fundamental Issues and Challenges ― Sample CFD Dynamic Mesh Model for Dynamic Wing ―Equations of Motion and Free Body Diagrams ― Static and Dynamic Analysis ― Control Design ― Non-linear Issues Summary and Conclusions Motivation Dynamic wing vehicles represent a leap in micro and nano-scale aerial vehicle design due to their size, agility and ability to carry small payloads such as surveillance equipment Vehicles that have hovering capabilities and can move at high velocity to a target efficiently are more desirable than the separate class vehicles such as slow moving 4-rotor MAV’s and a flapping bird MAV’s that requires foreword velocity to remain aloft Emphasis: Omnithopter, Capabilities include high foreword velocity and hover capability Issue: Model stabilities in both hover and foreword flight. Requires development of a suitable control system. PID controls for attitude stability are most crucial. Torque from the rotor system needs to be available for forward flight State of The Art State of the Art: Programs 1996-2000 – DARPA funding of Micro Air Vehicles ◦ DARPA Program initiative - develop and test technologies for mission capable flight system ◦ Only requirement –dimension of vehicle should not exceed 15 cm 2004 – 2005 – DARPA’s Goals ◦ integrate MAV technologies into militarily back packable systems for soldier, marine, and special-forces missions. 2009 – AeroVironment ◦ NAV program – Nano hummingbird, while not especially small, was a huge breakthrough in MAV ornithopter research because of its gyroscopically stabilized flight without any tail surfaces. ◦ 19 gram, 16cm wing span ◦ “will stretch our understanding of flight at these small sizes and require novel technology development.” Dr. Todd Hylton, DARPA program manager. 2012 – The Netherlands-Delft University of Technology ◦ Delfly II. 16 gram, 28 cm wing span 2012 – ASU Omnithopter- Arizona State University ◦ Omnithopter. 90 gram, 39 cm wing span Prior and Ongoing Work 1999- H. M. Blackburn, R.D. Henderson. "A study of two-dimensional flow past an oscillating cylinder" J. Fluid Mech. Cambridge University. 2007 - Berman, Gordon J. and Z. Jane Wang. “Energy-minimizing kinematics in hovering insect flight.” J. Cambridge University. 2007-Katherine Sarah Shigeoka, University of Utah, "Velocity and Altitude Control of an Ornithopter Micro Aerial Vehicle.“ 2009- Michael A. Bolender, U. S. Air Force Research Laboratory, "Rigid Multi-Body Equations of Motion for Flapping Wing MAVs Using Kanes Equations“. 2011-2012- ASU MAV Research team – – – – – Computational Dynamic Mesh for simulation of flapping wing & Control system dynamics for MAV’s. 6-DOF ornithopter, Electric motor driven axial wing articulation system, Aileron/elevator (ailevator) control within the advancing wing rotor system, CG shifting (pendulum) for roll stability. Sample Engineering Model Overview of Model Demonstrating the effects of the oscillating cylinder with an amplitude of 0.25, frequency is 0.89 Hz. Video of the Oscillating cylinder CFD simulation https://www.youtube.com/watch?v=gJ23DopzUc&feature=player_embedded Drag Profile for Oscillating Cylinder Drag coefficient Vs. Time Trend lines for the oscillating cylinder. Drag coefficient Vs. Time for the oscillating cylinder from Blackburn and Henderson. Dynamic Mesh Dynamic mesh of the oscillating cylinder moving up and down • Amplitude ratio of 0.5 • Amplitude ratio = ymax/D, • D is the diamter = 1, ymax = maximum displacement of the simple harmonic crossflow oscillation = 0.5 • Frequencies, fo, approximately 0.2. • F is the frequency ratio, F= fo/fv • fv is the fixed-cylinder vortex shedding frequency • fo is the frequency of the cylinder cross-flow oscillation Boundary Conditions Wind Tunnel Testing Wind Tunnel Testing of Avitron https://www.youtube.com/watch?v=ccpLl4Uoj5w Wind Tunnel Test Data Analysis Drag versus Velocity of Avitron Bird. Zero degrees and five degrees AOA Gliding and Flapping mode Velocity vs. Lift of Avitron Bird. Zero degrees and five degrees AOA Gliding and Flapping mode Wing geometry in Matlab and the actual wing of Avitron and Omnithopter • AVITRON AREA= 9.69 CM2 , WING SPAN =33CM • OMNITHOPTER WING AREA = 8.9 CM2 ,WING SPAN =39CM Equations of Motion and Free Body Diagrams Fundamentals of hovering for Omnithopter Velocity of wing (Linear) Drag due to mass of the vehicle and area of the wing Resistive force of wing Lift due to resistive force Power Required to produce Lift 1D Control Motion in the vertical direction: FW=Thrust F1=Force of wing By= vertical damping of the ornithopter Y=displacement F2=Accel force of vehicle in space Mg=Weight of vehicle