Autonomous Aerobatics: A Linear Algorithm and Implementation for a Slow Roll Student: Michael Brett Pearce1 Professors: Dr. Larry Silverberg2, Dr. Ashok Golpalarathnam3, Dr. Gregory Buckner4 Technical Expert on Aerobatics: John White, Master Aerobatic Instructor 2061858 CFI5 [email protected] [email protected] [email protected] [email protected] [email protected] Introduction Control Algorithm Methodology Custom Designed Airframe Unmanned Combat Aerial Vehicles ( ’s) are becoming common on the battlefield airspace but to date UCAV 1.21:1 Thrust to Twin Rudders for Yaw A pilot is essentially a PID Controller. The author’s unique aviation Control they have not been implemented in fighters due to the complexity of executing maneuvers required and VF-1 Valkyrie Weight Ratio the nonlinearities in aerodynamics, control response, control inputs required, and extreme attitudes. experience as a Certificated Flight Instructor and competition aerobatic pilot Custom Designed for project requirements Flapperons for Split Elevons for Thrust in powered and sailplanes is applied and converted to a mathematical basis. Hyper maneuverable aerobatic airframe with Slow Speed Flight Vectoring Such maneuvers are crucial for , low level penetration Air Combat Maneuvering (ACM, “dogfighting”) full 3-axis thrust vectoring with extreme maneuvering for bombing targets, escape and evasion from missiles, and "jinking" for This reduces the control problem to a linear system, bypassing the analytical, Capable of unlimited aerobatics and post stall avoiding ground to air gunfire. Such flying is collectively known as Basic Fighter Maneuvers (BFM). maneuvering computational, and monetary issues with a typical engineering approach. Onboard autopilot in a custom chassis BFM is fundamentally composed of aerobatics, and aerobatics itself is fundamentally composed of a few Foam core composite airframe stressed for in basic maneuvers. Humans are limited in their biological ability to withstand extreme maneuvering, thus Utilizing the existing codebase, the airframe launches and navigates to the excess of +/-15g autonomous fighter aircraft have the capacity to of completely redefine the current mission paradigm dogfighting, air superiority, and maneuvering. aerobatic box and aligns for the maneuver Advanced construction methods utilizing Input parameters of roll rate, entry speed, altitude, heading are handed CNC, laser cutting, and 3D Printing A slow roll is one of three primary fundamental maneuvers, and the objective of this research is to over to the algorithm, and ACRO mode is engaged Wingspan: 31.5” GPS implement an algorithm capable of flying a slow roll and its associated variations. Measure error in inertial frame, and rotate errors as a function of Φ to Oversized Control Surfaces Length: 45.3” convert to body frame for proper control deflection direction and scaling The algorithm is based upon methods utilized by the author that are taught to flight students as a Weight: 3.5 pounds Certificated Flight Instructor and utilized flying multiple different powered aircraft and gliders. Top Speed: 110~130 mph ∆α cosΦ sin Φ ∆Altitude = A concurrent objective is to design, fabricate, and flight test a suitable airframe capable of performing in FPV Camera such an extreme envelope, and implementing the necessary routines in an off the shelf autopilot. A robust ∆Ψ − Φ Φ ∆ sin cos Heading hyper-maneuverable airframe was designed, constructed, and flight tested as a test vehicle, with the flight controls implemented on an APM Autopilot with a software bridge to MATLAB. Rotated errors are used in a standard PID loop for elevator and rudder inputs. Roll and throttle are decoupled, with throttle increases linked to Pitot Static Probe The algorithm will be tested by having a fly-off between the airframe and full-sized aerobatic aircraft with altitude loss at full control deflection pilots, with the maneuvers judged on a standard criteria from the International Aerobatics Club. The scores Outputs sent to servos on control surfaces Low Aspect Ratio Wings of the algorithm will be compared against human pilots to give an assessment algorithm quality. with Symmetrical Airfoil for Extreme Roll Rate Carbon Fiber and 2200 mAh LiPo Fiberglass Reinforcement Battery ArduAcro Code Flowchart Linear Roll Algorithm Detail Telemetry Maneuver Inputs Downlink ArduACRO Chassis Existing ArduAcro Flight Mode Code (Heading, Mode ArduPlane Code Altitude, Entry Switch Aerodynamic Fairing for Flying the Slow Roll Speed, Roll Rate Drag Reduction Power ArduAcro Navigation ArduAcro Roll Set Points) Module Code Mode Vehicle Straight and Level to Determine Launch Switch to Start (same PID loop) Box Entry Acro Straight/Level Chassis Holding Autopilot along X Axis Mode No Securely During Extreme Maneuvering Airspeed/Altimeter Commanded Altitude, Yes Heading, Airspeed, Roll Sensor Navigate to ArduACRO Determine Rate Start Point Custom ArduACRO flight mode programmed in ArduPlane to Box Entry Cooling Measure Pitch, Roll, Intake implement autonomous roll algorithm Linear Yaw, Altitude, A slow roll is one of 3 fundamental maneuvers Roll Airspeed Custom MATLAB/MAVLink interface for communication Algorithm APM 2.5 and telemetry 360° roll with or without hesitations along the longitudinal axis while level, climbing, or descending Rotate Errors from 3-axis gyros and accelerometers Determine Inertial Frame to Body Box Exit Frame as a function of Φ Barometric Altimeter/Airspeed and 5Hz GPS Center of Gravity Track (CGT) Roll Criteria Atmel ATMEGA Processor Airspeed Roll rate must be constant throughout maneuver Pitch Error Yaw Error Roll Error 915MHz telemetry downlink Error 8 Channel Add'l Yes Roll must be in a constant plane for the Center of Gravity Maneuver Airspeed PID Spektrum RX Pitch PID Loop Yaw PID Loop Roll PID Loop ? Loop Track (CGT) RTL Output Output No Output PWM Output PWM PWM to PWM to to Elevons to Throttle No change in direction of flight during maneuver Rudder Aileron Vehicle Land Accurate and crisp angle stops between elements during point Vehicle Attitude Change VF-1 Valkyrie – Versus- Top Aerobatic Pilots rolls Eric Sandifer John White Brett Pearce Maintain axis in level or 45° climbing or descending flight 1,150 hours total time ~34,000 hours total time 500 hours total time Earned license in 2002, started Master Aerobatic CFI and Represented NCSU in Collegiate Aerobatics Division, flying aerobatics 2003 Air show Pilot placed 2nd nationally Flown in all IAC categories, Chief Pilot for Strongwell Certificated Glider Flight Instructor currently flying Unlimited in the Corp. Flight Testing, Data Collection, and Fly Off Pitts, 1St place wins in all categories, Test Pilot for Piper VF-1 Valkyrie “Roy Fokker” was flight tested and found to have 2015 Northeast Series Advanced Professional Aviator , Champion including experience in an excellent flight characteristics and met performance President of IAC Club 19 and was SU-25 Fighter requirements contest director at 7 contests Learned to fly in 1967, and was taught by his father The autopilot was calibrated and utilized in a fly-by-wire mode James Franklin White to tune APM Control gains. Tuning and final testing will be done at Old South Aerodrome (Private Airport, K32VA) Final data collection will be conducted by having a “Fly-off ” air Φ=0° Φ=45° Φ=90° “Knife Edge” Φ=135° show between human pilots and the Valkyrie using International Up elevator for level flight AoA Decreasing elevator Elevator for 0° AoA Increasing pitch down elevator Aerobatic Club scoring criteria and certified judges Reduce “top” rudder, maintain for Right rudder for P-factor, adverse Increasing right or “top” rudder Max right “top” rudder Aerobatic Contest Box and Axes yaw, torque, and spiraling slipstream for lateral AoA Aileron for steady state roll adverse yaw Fly-off Procedure Aileron input to initiate/stop roll Aileron for steady state roll Aileron for steady state roll Both manned and unmanned aircraft will fly a defined aerobatic sequence in a box under IAC rules Sequence will consist of at least 3 repetitions of various slow rolls 2 point, 4 point, 2/4, 1/2, and a “long” slow roll Multiple pilots and planes have volunteered to give an accurate comparison to human capabilities Scores will be processed and compared to validate algorithm performance Pitts S-1S, N100MP Extra 300, N300XT Designed in 1943 by Curtiss Pitts Designed by Walter Extra in 1987 as a composite, The Smithsonian described it as “revolutionary because unlimited class monoplane of its small size, light weight, short wingspan and extreme Started a monoplane revolution in air shows and agility” competition aerobatics Φ=180° Φ=225° Φ=270° “Knife Edge” Φ=315° Wingspan: 17’4” Wingspan: 24’3” Pitch down for level inverted flight Decreasing pitch down Elevator for 0° AoA Increasing up elevator Length: 15”6’ Length: 22’9” Right rudder for inverted effects of Decreasing/switching to new Maximum left “top” rudder Decreasing top rudder Weight: 1150 pounds Weight: 2,095 pounds 180hp 4 cylinder Lycoming 300hp 6 cylinder Lycoming upright flight “top” rudder Aileron for steady state roll Aileron for steady state roll Engine: Engine: Propeller: 2 blade fixed pitch Propeller: 3 blade constant speed Aileron for steady state roll Aileron for steady state roll Roll Rate: 180 deg/sec Roll Rate: 400 deg/sec G Limits: +6/-3g G Limits: +/-10g Top Speed: 176 mph Top Speed: 253 mph .