Software Enabled Control for Intelligent Uninhabited Air Vehicles UAVs GTMax Flight Testing

1
Software Enabled Controlfor Intelligent
Uninhabited Air Vehicles (UAVs)GTMax Flight
Testing

• Principal Investigators
• Daniel Schrage (AE) George Vachtsevanos (ECE)
• School of Aerospace Engineering School of
  Electrical and Computer Engineering
• Georgia Tech Georgia Tech
• Atlanta, GA 30332 Atlanta, GA 30332
• daniel.schrage_at_ae.gatech.edu george.vachtsevanos_at_e
  ce.gatech.edu
• [phone] [phone]
• Co-PIs and Key Personnel
• Bonnie Heck (ECE), Eric Johnson (AE), J.V.R.
  Prasad (AE), Linda Wills (ECE)

controls.ae.gatech.edu/projects/sec
2
Outline

• Update on GTMax system
• Review of flight testing process
• Discussion about Friday

3
Georgia Tech R-Max GTMax

• Yamaha R-Max,
• 66kg
• 3m Rotor
• Flights Began March 2002

• Instrumented as a Research VTOL UAV
• OCP, Simulation Tools
• Modular Avionics Hardware

4
GTMax Hardware Components

• Flight Computers
• 266MHz 850 MHz Embedded PCs, Ethernet, Flash
  Drives
• Sensors
• Inertial Measurement Unit (x2)
• Differential GPS
• Magnetometer
• Sonar and Radar Altimeters
• Vehicle Telemetry (RPM, Voltage, Pilot Inputs)
• Data Links
• 11 Mbps Ethernet Data Link
• RS-232 Serial Data Link

5
Basic GTMax Avionics
6
GTMax Flight System Architecture
GPS Reference
GPS
Georgia Tech Onboard Avionics
Data Link I
Data Link I
Ground Computer(s) And Network
GEORGIA TECH
Ethernet
Data Link II
Data Link II
Ground Control Station
3x RS-232 Serial
RC Receiver
Yamaha Attitude Control System (YACS)
YAMAHA
On-board Avionics
Safety Pilot
Actuators
7
Potential Actuator Failure Scenarios
Scenario
Description
Effect
Reconfiguration
Main rotor collective is stuck in a known
position.
Vertical acceleration can not be controlled by
the collective.
Use RPM to control vertical acceleration.
1. Stuck Collective
Use altitude (or vertical acceleration) to
compensate for loss of rpm control (i.e.,
Autorotation).
Throttle is stuck in a known position or goes to
zero (engine failure).
RPM can not be governed as is traditionally done.
2. Throttle Stuck / Engine Failure
Use thrust and collective control to control yaw
acceleration.
3. Tail Rotor Stuck / Transmission Failure
Tail rotor is stuck at a given pitch or stops
rotating altogether.
Yaw acceleration can not be controlled by the
tail rotor.
8
Baseline Software Overview

• Onboard software
• Primary flight computer
• GCS software
• Runs on ground control station
• Simulation software
• Not used in flight
• All of the above included in GCS/Simulation build
• Only onboard software include in onboard or OCP
  build

9
Baseline Onboard Software

• Navigation
• 17 State Extended Kalman Filter Navigation System
• Vehicle Position
• Vehicle Velocity
• Vehicle Attitude
• Accelerometer Biases
• Gyro Biases
• Terrain Height
• All Attitude Capable
• 100 Hz Updates
• Flight Operational

• Control
• Adaptive Neural Network Trajectory Following
  Controller
• Neural Network
• 16 Inputs
• 5 Hidden Layer Neurons
• 6 Outputs for 6 Degrees of Freedom
• Can Also Be Configured as a Conventional
  Inverting Controller
• Flight Operational

10
Neural Network Adaptive Control
PCH
Command
-
DynamicInversion
Plant
Reference Model
Actuator


Neural Network
PDControl
Tracking Error
11
Inner-Outerloop Architecture
12
Helicopter approximate model
Attitude dynamics
Translational dynamics
13
Helicopter Inverse
14
Baseline Control/Navigation System Flight Testing

• Envelope expanded 50 to 80 ft/sec speed
• Have experienced up to 40 knot gusts (estimated)
• First automatic takeoff and landing
• First automatic aggressive maneuvers

15
Race Track
16
40 fps dash at 10ft/s2
17
80 ft/sec Automatic Cruise
18
Automatic Takeoff and Climb
19
Automatic Aggressive Maneuver
180 Degree Velocity Change in a congested
environment
gt60 Degrees Max Pitch Angle
Go high to avoid Saturating collective
(de)Accelerate 2/3 G
Start and Finish at 30 Knots
Keep nose aligned with velocity (zero sideslip)
throughout
60 ft
20
1800 Velocity Change
21
Automatic Approach Landing
22
Summary Procedure

• Develop Scenario and Test Plan
• Define and Implement Interface(s)
• SITL Simulation
• HITL Simulation
• Flight Test

23
Software in the Loop (SITL) Single CPU
Desktop Computer
Vehicle Model
Sensor Emulation (w/ Error Model)
Actuator Model
State
Control
Sensor Raw Data
Actuator Raw Data
Other Systems
Command Vector
Sensor Drivers
Actuator Driver
Sensor Data
State Estimate
Flight Controller
Navigation Filter
Control
24
Hardware in the Loop (HITL) Primary Flight
Computer

• Flight software runs on the onboard computer
• Onboard computer thinks it is flying the vehicle

Desktop Computer
Vehicle Model
Sensor Emulation (w/ Error Model)
Actuator Simulation
State
Control
Sensor Raw Data
Actuator Raw Data
Sensor Drivers
Actuator Driver
Sensor Data
State Estimate
Flight Controller
Navigation Filter
Control
Command Vector
Flight Computer or Test Computer
Datalinks Ground Control Station
25
Flight Computer Interface
Signal LimitInfo Position(x,y,z) Velocity(x,y,z)
Acceleration(x,y,z) Time Delf, Delm(x,y,z) Rpm
Limit Avoidance Component
50 Hz
Low Level Flight Controller, Navigator
Datalink Component
LimitInfo
LimitDecl
Signal LimitDeclaration AccelerationLimit(x,y,z)
Ethernet UDP Comm
UAVState
50 Hz
Mission Trajectory Planning Component
SetPoint
25 Hz
Signals UAVState SetPoint Position(x,y,z) Veloc
ity(x,y,z) Phi, Theta, Psi p, q, r
Primary Flight Computer
Secondary Flight Computer
26
Available Data

• Available Onboard
• Raw Sensor Data, Pilot Inputs
• Processed Navigation Solution
• Ground Station Communication
• Available On the Ground
• Network Connection to Onboard Computers

27
Software in the Loop (SITL) Secondary Flight
Computer
Actuator Raw Data
Sensor Raw Data
Sensor Drivers
Actuator Driver
Sensor Data
State Estimate
Flight Controller
Navigation Filter
Control
Command Vector
Simulation of Primary Flight Computer,
Helicopter, Sensors
Datalinks Ground Control Station
OCP Mid-Level ControlComponents
Navigation DataTrajectory Commands
Sim of Second Computer
28
Hardware in the Loop (HITL) Secondary Flight
Computer
Actuator Raw Data
Sensor Raw Data
Sensor Drivers
Actuator Driver
Sensor Data
State Estimate
Flight Controller
Navigation Filter
Control
Command Vector
Simulation of Primary Flight Computer,
Helicopter, Sensors
Datalinks Ground Control Station
OCP Mid-Level ControlComponents
Navigation DataTrajectory Commands
Second Computer
29
Flight Configuration (Current)
Actuator Raw Data
Sensor Raw Data
Sensor Drivers
Actuator Driver
Sensor Data
State Estimate
Flight Controller
Navigation Filter
Control
Command Vector
Primary Flight Computer
Datalinks Ground Control Station
OCP Mid-Level ControlComponents
Navigation DataTrajectory Commands
Second Computer
30
What to Expect Friday

• Examine equipment and test field
• See flight test operation (for the most part a
  typical one)
• Automatic flight
• Takeoff, landing
• Maneuvers
• Trajectory generation test
• Limit detection and avoidance test
• See ground control station
• Use of simulation at the flight test field

31
Field Layout
Helipad
No fly zone
GCS truck
Remain behind until after flying
Remote monitoring of GCS
Seating
32
Things to consider

• Sunscreen
• Sunglasses/hats
• Appropriate shoes
• Tour the labs tomorrow