multi-axis independent electromechanical load control for
TRANSCRIPT
Multi-Axis Independent Electromechanical Load Control for Docking
System Actuation Development and Verification using dSPACE
dSPACE Technology Conference
Christopher Oesch – Moog
Brandon Dick – Boeing
Timothy Rupp – NASA
October 13-14, 2015
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Abstract
The development of highly complex and advanced actuation systems to meet
customer demands has accelerated as the use of real-time testing technology
expands into multiple markets at Moog. Systems developed for the autonomous
docking of human rated spacecraft to the International Space Station (ISS),
envelope multi-operational characteristics which place unique constraints on an
actuation system. Real-time testing hardware has been used as a platform for
incremental testing and development for the linear actuation system which
controls initial capture and docking for vehicles visiting the ISS.
This presentation will outline the role of dSPACE hardware as a platform for rapid
control-algorithm prototyping as well as an EMA system dynamic loading
simulator, both conducted at Moog to develop the safety critical Linear Actuator
System (LAS) of the NASA Docking System (NDS).
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Presentation Overview
• Company Information
• Introduction of Docking System Concept of Operations
• Hardware Configurations
• Expansion to Multi Axis
• System Testing with Independent Multi-axis EMA Control
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Company Overview
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Company Overview Slides
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Docking System Introduction
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Docking System Operations
• Concept of operations for initial docking and control to hard capture requires
three major control modes from the actuation system controlling the 6 degree of
freedom interface docking ring mechanism:
1. Position control (unloaded and mass loaded)
2. Motion damping
3. Slip force regulation
Ground
Integration & TestLaunch On-Orbit Checkout
Initial Contact
Force Regulation
Motion DampingVehicle AlignmentRetractHold for Hard
Capture
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Mechanism Concept
Image Credit: www.nasa.gov
Image Credit: www.nasa.gov
Visiting Spacecraft Interface Adapter
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Need for Advanced Testing Techniques
• Autonomous docking sequence testing was required
– All control modes are exercised during the test sequence
– Multiple configurations of initial conditions were required
• Actuation system had to be tested independent of the docking mechanism
interfaces
– Required independent test load control, simulating docking loading scenarios
• The selected development process required flexible testing solutions
– Build, test, update models, update requirements…repeat
– Rapid system development – development timeline ranked highest on program importance
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Testing Hardware
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Flexible HIL Control Platform
• dSPACE chassis
– DS1006 processor card
– DS5203 FPGA card w/ expansion I/O
• 3x for multiple EMA control
– DS2004 A/D card
– DS2102 D/A card
• Sensor interface modules
– Voltage buffers
– Current drivers
• Oscilloscope
• BNC I/O Interface
• ControlDesk Next Generation
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Initial Proof of Concept Setup
• Initial proof of concept was utilized to demonstrate initial concept of operation
for strut control
• Platform for rapid control prototyping
• System identification techniques were developed
• Built user knowledge of dSPACE software
• Configuration:
– Single brushless DC motor EMA
– Hydraulic load actuator
– Load controlled by position only
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Proof of Concept Phase
• Moog developed a rapid prototyping proof of concept test stand platform to test
electromechanical options for initial control demonstration
• dSPACE was used to control both the unit under test and the load cylinder
• Rapid prototyping served as a useful mode of operation to develop
requirements and iterate on design solutions
• System identification techniques were developed for model correlation
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Single Channel EMA and Hydraulic Test Stand
Servovalve
Manifold
Motor
Control
Interface
46Vdc
Load
Cell
Cond
EMA LOAD CELL
HYDRAULIC LOAD CELL
Servo
InterfaceSERVOVALVE
LDT
LDT
1525mm (5 ft)
Resolver
RETRACT PRESSUREEXTEND PRESSURE
dSPACE
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Single Channel EMA and Hydraulic Test Stand
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Multiple Axis Expansion
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Test Stand Configuration Change
• Desire to create a simulated variable inertial load reflected to the unit under test
• Challenges with hydraulic load cylinder
– Complicated non-linear dynamics between servovalve and output were a challenge to
compensate against
– Control of force was completed by an unbalanced cylinder
– Pressure systems were at the mercy of facility pump supplies
• An EMA load cylinder
– Mechanical characteristics between servo input (motor) and output (force) are easier to
system ID
– Ability to create a very large reflected inertia
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Dual EMA Configuration
• EMA #1 – Unit Under Test
– Rapid control prototyping and system ID of latest flight actuator design
– Multiple control modes
• EMA #2 – Load Cylinder
– Position loop control
– Dominating capability with very large reflected inertia
– Inertia simulation control
• dSPACE configuration update
– Two DS5203 FPGA cards with expansion I/O used to control two EMAs
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Dual Channel EMA Test Stand
Load Actuator Control
Laws
· Constrained Position
· Inertial Load
Simulation
dSPACE HIL Platform
Data Logging and Feedback
UUT Control Laws
· Mode and Function
Transition
· FC Commands
Sensors:
Position Transducer (2)
Resolver (2)
Load Cell (2)
Accelerometer (2)
Current Sensor (4)
Flexure
LOAD ACTUATORSCS PATHFINDER
Power Stage
Phase A Current
Phase B Current
Phase A Current
Phase B Current
Pathfinder Sine
Pathfinder Cosine
Pa
thfi
nd
er
Po
sit
ion
Pa
thfi
nd
er
Fo
rce
Pa
thfi
nd
er
Ac
ce
l
Lo
ad
Ac
ce
l
Lo
ad
Fo
rce
Lo
ad
Po
sit
ion
System ID Excitation
Functions
Load SineLoad Cosine
SLED 1 SLED 2
Power Stage
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Dual Channel EMA Test Stand
Load EMA UUT EMA
Sled 1 Sled 2
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Six Axis Load Control
• Full up UUT system testing needs:
– Six axis independent control
– Flexible inertia simulation
– Synchronized initial test conditions
• dSPACE configuration:
– Two EMA controllers in a single
DS5203 FPGA card with expansion I/O
– Three DS5203 cards
– DS1006 processor board
DS1006 – Single Core
EMA #1 Loops
PositionVelocity Current
Inertia Sim
EMA #2 Loops
PositionVelocity Current
Inertia Sim
EMA #3 Loops
PositionVelocity Current
Inertia Sim
EMA #4 Loops
PositionVelocity Current
Inertia Sim
EMA #5 Loops
PositionVelocity Current
Inertia Sim
EMA #6 Loops
PositionVelocity Current
Inertia Sim
Supervisor Logic
DS5203 FGPA #1
Resolver Excitation / Demodulation
3-Phase PWM Control
Resolver Excitation / Demodulation
3-Phase PWM Control
DS5203 FGPA #2
Resolver Excitation / Demodulation
3-Phase PWM Control
Resolver Excitation / Demodulation
3-Phase PWM Control
DS5203 FGPA #3
Resolver Excitation / Demodulation
3-Phase PWM Control
Resolver Excitation / Demodulation
3-Phase PWM Control
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Multi-axis EMA Test Stand
Power Stage x6
dSPACE Real Time
Controller
(Inertial Load
Simulation and
Constrained Position)
Moog Test Console and
Flight Controller SimulatorMTI and RT Data Recording
Command Interface
System
Controller
String A, String B
Load Actuator #1
Load Actuator #2
Load Actuator #3
Load Actuator #4
Load Actuator #5
Load Actuator #6
LAS UUT LA #1String A, String B
LAS UUT LA #2String A, String B
LAS UUT LA #3String A, String B
LAS UUT LA #4
String A, String B
LAS UUT LA #5String A, String B
LAS UUT LA #6String A, String B
Electromagnet
Control Box
Electro
mag
nets
Load
Cells
Load
Cells
External Position Sensor (x6)
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Six Axis Test Rig
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Six Axis Test Rig
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Docking System Testing
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Summary & Future Work
• Flexible dSPACE testing hardware enabled rapid control development of
docking actuation systems
• The testing platform enabled a development approach of build, test, update
requirements, repeat
• The platform was expanded to multi axis control enabled system level
verification
• Technology developed: EMA test equipment platform, system ID techniques,
inertia simulator
• Future work
– Utilize six-axis simulator to provide load control for flight system qualification testing
– Expand inertia simulator technology to high power actuation system control
– Develop high power EMA dSPACE power stage
– Utilize FPGA platforms for VHDL V&V
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Thank you!
Questions?