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

Changes in AFRL/RBCA

The AFRL MAV Vision

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

Insect Scale Flapping Wing Vehicles Credit: Robert Wood, Harvard University 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

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 DAQ FW MAV EOMs Control Law Forces Moments Wingbeat Parameters Real-Time Data Acq, Sim & Ctrl DAQ = Data Acquisition FW = Flapping Wing EOM = Equations of Motion 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

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 Yaw Roll Slow Translate Maneuvering via Split-Cycle Constant-Period FM Wing position Time (fixed period) Reduced Velocity Increased Velocity Symmetric wing beat Run 6 DOF flight control tests on modified RoboFly class MAV Independently controlled wings/passive rotation CG actuator Split-cycle constant-period frequency modulation

Indoor Flight Test Facility Helicopter Wand Following/AFRL MAV Lab July 2008 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 Single channel of control law Outer-loop: Position command, Inner-loop: Attitude command Helicopter Flight Test Purpose:  Debug hardware and software using COTS MAV prior to flapping wing experiments.

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