Control Science Center of Excellence Overview

1. Control Science Center of Excellence Overview SAE Aerospace Guidance & Control Committee Meeting 17 Oct 2008 Dr. David B. Doman Control Design and Analysis Branch Air Vehicles Directorate Air Force Research Laboratory

2. Changes in AFRL/RBCA

3. The AFRL MAV Vision

4. Micro Air Vehicle (MAV) Control Research Objectives • Enable stabilized and controlled flight for flapping MAVs designed for warfighter support • Insect-like maneuverability, hover, forward, backward, lateral movement • Deliver flight control and trajectory generation capabilities to enable perching on fixed object in the presence of disturbances

5. Insect Scale Flapping Wing Vehicles • RoboFly built by Prof. Robert Wood of Harvard University • First flight of insect scale flapping wing vehicle • 3 cm wingspan, 60 mg mass • Passive wing rotation, single piezo-electric actuator • Off-board power, no sensors • Uncontrolled flight up a wire • Elegant design, minimal actively controlled elements • AFRL undertaking analysis of 6 DOF experimental vehicle • Independently actuated wings • C.G. controlled via piezoelectric • Passive 6 DOF sensors via Vicon • Use to develop control strategies Credit: Robert Wood, Harvard University

6. Hardware-in-the Loop Control Experiments • Build MAV with two independently actuated wings with passive wing rotation • Use MAV 6 DOF test stand to measure forces and moments to verify hypotheses • Why do this: • Account for modeling errors due to use of blade element theory • Test feedback control • Examine effects of amplitude modulation and mixed frequency/amplitude modulation of wing motion • Examine effects of waveform shape on forces and moments • Quantify coupling between moments for insight into control allocation Forces Moments FW MAV EOMs DAQ Wingbeat Parameters Control Law Real-Time Data Acq, Sim & Ctrl DAQ = Data Acquisition FW = Flapping Wing EOM = Equations of Motion

7. Roll Yaw Slow Translate Experimental Verification of Control Strategies • Run altitude control test for “Bug on a Wire” • RoboFly class MAV, Single Actuator • Passive altitude/altitude rate sensors using Vicon cameras • Off-board processing, off-board power source, wire power transmission • Verify feasibility of FM-based control law Closed-Loop Wingbeat Frequency Modulation Reduced Velocity Increased Velocity Wing position • Run 6 DOF flight control tests on modified RoboFly class MAV • Independently controlled wings/passive rotation • CG actuator • Split-cycle constant-period frequency modulation Symmetric wing beat Time (fixed period) Maneuvering via Split-Cycle Constant-Period FM

8. + + - - - - Indoor Flight Test Facility • AFRL MAV Laboratory Capabilities: • Vicon Camera system for position/attitude measurement • Rapid flight control prototyping & analysis using LabView Real-Time Deployment Option & Matlab/Simulink with Real-Time Workshop • Helicopter Flight Test Purpose: • Debug hardware and software using COTS MAV prior to flapping wing experiments. Helicopter Wand Following/AFRL MAV Lab July 2008 Single channel of control law Outer-loop: Position command, Inner-loop: Attitude command

9. Plans for the Near Term • AFRL Current Plan of attack for MAV flight control • Simple first principles modeling to develop control strategies • Experimental testing to correct blade-element aero models for unsteady effects • Incremental flight testing from “Bug on a Wire” to 6 DOF • AFRL indoor flight test facility allows focus on MAV control challenges • Passive inertial sensing using Vicon Motion Capture System gets sensors off of the MAV • Off-board flight control processing eliminates weight and enables rapid flight control prototyping • Off-board power for piezoelectric actuated aircraft • Translation of flight control commands from real-time computer to RF transmitter signals for MAVs • Allows progress on flight control front while battery and sensor technology are advancing • Right combination of tools to make progress toward objective of enabling insect-like maneuverability for MAVs