CORBA in Control Systems
Presented at the OMG Workshop On Distributed
Object Computing For Real-Time and Embedded
Systems, Washington, DC, 14-17 July 2003
Dr. Shahzad Aslam-Mir, Prism Technologies
Dr. James L. Paunicka, Boeing
Eric J. Martens, Boeing
AHS International 59th Annual Forum 2003
• Sam’s slides:
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Intro
Control Systems
Importance of CORBA in Control
Current schools of thought on CORBA applicability in control systems
Historical perceived limitations on CORBA use in control loops
Case studies
AHS International 59th Annual Forum 2003
Flight Control Example
• Standards-based CORBA middleware used in live flight of a
commercial rotorcraft UAV in May 2002
– Flight test was collaboration between Boeing and Georgia Tech School of
Aerospace Engineering
» Boeing – embedded software architecture, integration of software on
embedded processing platform
» Georgia Tech – flight vehicle, vehicle control software
AHS International 59th Annual Forum 2003
Flight Control Example
• Flight test was part of the DARPA IXO (Information eXploitation Office) SEC
(Software Enabled Control) program
– Significant technical direction from Air Force Research Laboratory
» Information Systems, Advanced Architecture
and Integration organization
» Air Vehicles, Control Systems Development
and Applications organization
– Leverages OCP (Open Control Platform) being developed on the SEC program
» Middleware platform that adapts Boeing Bold Stroke software technology to the domain
of flight vehicle control
» ACE/TAO
» Run-time optimizations to support flight vehicle control
» API for flight vehicle control applications (“Controls API”)
» Developed by Boeing-led team that also includes Georgia Tech, University of
California-Berkeley, and Honeywell
AHS International 59th Annual Forum 2003
Background
• SEC funds two
technology areas
– Control technology for
flight vehicles
» Fixed-wing and rotorwing
UAVs
» Multiple research teams
from industry and
academia
– Enabling Software
technology
» Adapt Boeing Bold Stroke
software technology to the
domain of flight vehicle
control
AHS International 59th Annual Forum 2003
Software Application
Components
OCP Middleware
Download
Open Systems Software
Open Systems Hardware
Online
Model
Controller
Gnd
Station
Controls API
OCP Middleware Extensions
ACE & RT CORBA (TAO)
Operating System & Board Support Package
Hardware (CPU, Memory, IO)
Commercial UAV Flight Vehicle
• Yamaha R-Max autonomous helicopter
– Couple hundred pounds,
– 10-foot main rotor diameter
• Fitted with open systems avionics platform for SEC program
experimentation
– Sensors
» IMU (Inertial Measurement Unit), GPS, sonar for altimeter, magnetometer
for compass
– Actuators
» Throttle, main rotor, tail rotor
– Comms
» Wireless ethernet
» Wireless serial link
– Onboard compute platform
» Single 266-MHz Pentium II processor
AHS International 59th Annual Forum 2003
R-Max Vehicle
AHS International 59th Annual Forum 2003
Autonomous Helicopter Electronics
Open Systems Equipment Bay
Actuator Command Path
Switch (Pilot & YCS controlled)
R/C Link
Yamaha R/Max Sensors
R/C Pilot
Control Box
Yamaha Control
System (YCS)
Yamaha Hardware
Side
YCS Actuator Cmd’s
YCS System & Sensor Data
Open Systems
Avionics
Wireless Ethernet Link
Wireless Serial Link
GIT Actuator Cmd’s
IMU
GPS
AHS International 59th Annual Forum 2003
Sonar
Magnetometer
R-Max Actuators
(blades & throttle)
Flight Test Embedded Software Architecture
• Major Elements
– Lowest level – VxWorks RTOS and appropriate BSP (Board Support
Package)
– Middleware level – Open Control Platform from SEC program
– Application software level – multiple components written by Georgia
Tech
• Run-time configuration of CORBA-based software
– Middleware triggered execution of multiple software components with
EC (Event Channel)
» 100 Hz operation
• Triggered the start of inner-loop control processing with the arrival of IMU data
– Middleware mediated I/O among the various aircraft sensors, flight
control actuators, and multi-level control loops
– Implemented a software reconfiguration in flight
» Neural net adaptive controller switching to a conventional inverting
controller
AHS International 59th Annual Forum 2003
Flight Test Embedded Software
Architecture in Context
GPS (Signal A at 5 Hz & Signal B at 5 Hz ... not at same time)
Controls API Input Port
Sensors Serial
Interface
Controls API Output Port
Magnetometer (20 Hz)
sonar (40 Hz)
<Signal Name> - passed signal
IMU (100 Hz)
IMUTrigger
Global Data
Storage
Vehicle Serial
Interface
RMAX Attitude sensors (200 Hz)
receiver commands (40 Hz)
I/O
Component
Vehicle Health (? Hz)
DataLink Interface
Ethernet “Serial” Port
Serial port
NavDataOutputPort
1 Hz & 10 Hz
<NavRunCommand>
1 Hz & 10 Hz
Ethernet “Serial” Port
Serial port
Input datalink ports
read @ 100 Hz
m0 written at 10 Hz
m1 written at 1 Hz
100 Hz
NavDataInputPort
Navigation Module
Component
NavControlOutputPort
NavControlInputPort
Controller
Component
Actuator Serial
Interface
50 Hz
<ControlRunCommand>
50 Hz
AHS International 59th Annual Forum 2003
RMAX Actuator demultiplexer
Flight Test Embedded Software
• Multiple Application Components,
including
– I/O Handler
– Navigation Processing
» Also handles data link updates
– Controller Processing
• OCP Frame Manager launches
100-Hz loop after 16-byte IMU
burst
– Pushes an event to start I/O
Handler
• Other components also initiated in
100-Hz frame with event pushes
• Middleware-Based Reconfiguration
accomplished with OCP activating
and deactivating different
controllers
AHS International 59th Annual Forum 2003
WindView Plot of OCPBased Application
Flight Test Timeline
• R/C (Radio Control) pilot
performed take-off (and subsequent
landing) using baseline Yamaha
flight control system
• While in flight, rotorcraft switched
to open systems research flight
control system
– With RT-CORBA-based flight
control program
• Transition between vehicle
controllers (neural net to
conventional inverting controller)
triggered by ground station
command and accomplished by
middleware
AHS International 59th Annual Forum 2003
Video from Flight Test
• Sam’s slides:
– Analysis of where we are
– Conclusions
AHS International 59th Annual Forum 2003