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Organic Air Vehicle (OAV) Flight Control An Application of Multi-Application Control (MACH)

Organic Air Vehicle (OAV) Flight Control An Application of Multi-Application Control (MACH). Dale Enns Honeywell 4 March 2005 SAE AEROSPACE CONTROL AND GUIDANCE SYSTEMS COMMITTEE Salt Lake City, Utah. Introduction. Vehicle. Missions.

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Organic Air Vehicle (OAV) Flight Control An Application of Multi-Application Control (MACH)

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  1. Organic Air Vehicle (OAV) Flight ControlAn Application ofMulti-Application Control (MACH) Dale Enns Honeywell 4 March 2005 SAE AEROSPACE CONTROL AND GUIDANCE SYSTEMS COMMITTEE Salt Lake City, Utah

  2. Introduction Vehicle Missions Takeoff, ascend, hover, rotate, translate, descend, land autonomously and with pilot in the loop

  3. Design Theory x = States incl. p, q, r, u, v, w, … u = Control Surfaces y = p, q, r • True Aircraft Model (TRAC) • Controlled Variable (CV) • Calculus and On-board Aircraft Model (OBAC) • Dynamic Inversion • Feedback Controls C x x x x X TRAC OBAC x x u x y K f(x,u) h(x) a(x)

  4. Basic Feedback Loop • Proportional Gain = • Integral Gain = • Command Gain = • Anti-Integral Windup Gain = • Closed Loop Transfer Function = • Loop Transfer Function (at y) = _ _ _

  5. Control Law Structure Inner loop pair Outer loop pair Position Commands Throttle Command Velocity Commands Angular Rate Commands Attitude Commands Vane Commands Heading Command

  6. Control Allocation Approach Given B and d find u to minimize || Bu – d ||2 Subject to constraints umin < u < umax Constraints include worst case of Position and rate limits Desired d is unachievable so find Closest approximation with axis prioritization u2 d2 d = B u u1 d1 Solution involves finding the intersection of two ellipsoids

  7. Unique Inverse • Montontonicity for scalars • Example for 2 dimensions We require that the Jacobian not change sign over the region of interest Jacobian = Such that the solution to has a unique solution for a given d f(u) f (u) Solution 1 Solution 2 u d Jacobian > 0 Jacobian < 0

  8. 2x2 Example of Non-Unique Inverse f(u) is piecewise linear, continuous Slopes of diagonal are equal to 1 Off-diagonal slopes change at the origin • In Quadrant 1 • f1 = u1 + 3/2 u2 • f2 = 1/3 u1 + u2 • In Quadrant 2 • f1 = u1 + 3/2 u2 • f2 = u1 + u2 • In Quadrant 3 • f1 = u1 + 1/2 u2 • f2 = u1 + u2 • In Quadrant 4 • f1 = u1 + 1/2 u2 • f2 = 1/3 u1 + u2 • Mapping of • -2 < u1 < 2 • -2 < u2 < 2 Jacobian = 1/2 Jacobian = -1/2 Jacobian = 1/2 Jacobian = 5/6

  9. Closed Loop Poles = Open Loop Zeros Open Loop Dynamic Inversion Theorem Closed Loop for

  10. OAV Integrated Avionics – AV2 +3.3V GPS Rcvr Base Station µHard Modem Interim RadioReceiver Serial +5V WOW GND +5V Serial Serial +15V -15V +5V CMOS Camera FMU 2.4GHz VideoTransmitter Engine Speed Pulse Train InfraRed Camera IMU GND +5V Altimeter I2C Serial PWM GND 1 A/D +5V Air Data 2 GND FMU H/W +V Magnetometer x-axis 3 Servo 1 GND y-axis 4 External H/W z-axis 5 Servo 2 Payload H/W Temperature 6 Servo 3 Comm. H/W Battery State 7 Servo 4 8 Engine Temp Engine Throttle

  11. Honeywell Intl. Proprietary OAV Avionics • Flight Management Unit • MEMS IMU HG-1900 • GPS • Blended GPS/Inertial Nav & Attitude information • Flight Control Laws • Actuation commands • Flight Control Surfaces • Engine Throttle • Payload selection • Payload pointing • Commonality of hardware leads to lower cost - common gun-launched IMU entering high volume production IMU FMU

  12. Flight Controls Adverse Weather Issues • Hover in steady wind • Vehicle will tilt into the wind • More tilt for more wind • Gusting winds • Vehicle will tilt back and forth to adjust to changing wind • Non-minimum phase response • Measurements of airspeed relative to vehicle lead to improved performance • Direct sensing • Estimation • 3 components of relative wind

  13. Hover in Steady Wind Force Balance Moment Balance Tilt from Vertical T L Wind D Duct Nose Up Vanes Nose Down d Wind Along mg da Pitch Axis Roll Axis Vane Deflection for Trim (Degrees) de Large Roll Vane Deflection Required for Trim at Intermediate Speeds 20 30 40 10 Horizontal Wind Speed (Knots)

  14. OAV Specifics • On-board Aircraft Model (OBAC) • 3 Forces and 3 Moments are Dependent Variables • Combine table lookup and analytical expressions for forces and moments • Rigid body with propeller/engine momentum equations of motion • Wind Estimator Wind Estimate Accels Estimation Gains Modeled Accels OBAC Measurements

  15. Robust Stability Analysis Control Law Plant Introduce Multiplicative Perturbations at all interfaces between Plant & Control Law K _ Unacceptable log 10 Negotiable M Satisfactory 0

  16. MOVIE OF OAV FLIGHT TEST 1 July 2004 Ft. Benning, Georgia

  17. Conclusions • Multi-Application Control (MACH) • Reusable control law • Robust, versatile, modular, nonlinear, multivariable design • Other Applications of Dynamic Inversion • X-35 Lockheed Martin Joint Strike Fighter • X-38 Prototype Crew Return Vehicle

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