development of guidance and control system for parafoil-payload system vvr subbarao, sc ‘c’...
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Development of
Guidance and Control System for
Parafoil-Payload System
VVR Subbarao, Sc ‘C’Flight Mechanics & Control Engineering
ADE
09 June 07 Workshop on Mathematical Engineering
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Parafoil-Payload System
• Control Surfaces – 1 pair at the Trailing Edge
• Symmetrical Deflection
• Changes flight path angle and rate of descent
• Asymmetrical Deflection
• Generates turn
Cell`
Leading Edge
Payload
Steering Lines
Suspension Lines
Stabilizer Panels
Differences with Aircraft
• Flexible lifting surface
• Centre of mass is suspended below canopy
• Control is achieved by changing parafoil shape
• No external power to push forward
Advantages• Sufficient glide and wind penetration• Low potential damage to payload• Fly aircraft at safe stand-off distance• Greater offset distance for given altitude
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CADS
Name Controlled Aerial Delivery SystemObjective To demonstrate the technology for precise delivery of a payload of 500 kg using a Ram Air Parafaoil
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Airborne Guidance &Control System`
TaskTo develop Airborne Guidance and Control System to meet
required CEP of 100m
Followed Strategy• Phase I
– Developing path control in 2-D plane on 80kg p/p system• To assess the control effectiveness of parafoil• To arrive the suitable guidance and control scheme
• Phase II– Development of guidance and control scheme to make touch down
within 100m CEP• Design of Energy Management Maneuvers• Extension of these CLAW for 300kg parafoil
Phase I
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Issues• Simulation Model
– Conventional 6 DOF equations do not hold– Multi-body dynamics
• 4, 6, 9, 12 Degree-of-Freedom– Lifting surface is not rigid
• Flexible canopy
• Aerodynamic Data– Not available at the beginning– Data was generated semi-rigid canopy– Later data available only for 500kg parafoil
• Stability and control derivatives• No rate derivatives
• Data Generation Trials– Controlled from ground– Planned data generation trials– Developed 4 DOF model
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Ground based Guidance and Control System Architecture
Analog
RS 232On-Board Sub-Systems
PFCC BL 2120
Actuators
GPS Receiver
Alt. Sensor
Heading
DRUNMEA
Tx,Rx
Tx, RxPt & SB Lanyard Commands
Ground Sub-Systems
JoyStick
Issues
•Vehicle state information
•Sensors Mounting
•Sensors selection
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4 DOF Mathematical Model
• Assumption– parafoil-payload (p/p) load system as a single rigid body.
• Simulates – the forward and downward translations
– roll and yaw (turn) motions of the para-foil.
– Does not required much aero data
• Used– to finalize the implementation of control laws
– In Hardware-In-Loop Simulation to close control loop
– To design failure logics
– Train ground pilot
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Guidance and Control Scheme
Autonomous Mode•Two loop
•Outer loop•Cross-track error minimization
•Inner loop•Heading error minimization
Sensors•Main
•GPS•Monitoring
•Static Pressure•Compass
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AG&CS Architecture
ParaFlight Control
Computer
On-board DRU
HeadingSensor
GPS Antenna
IAS Transducer
Altitude Transducer
Proximity Sensor
Port Lanyard Actuator
StarboardLanyardActuator
HandheldTerminal
TX/RX CBL 2120
Parachute Power Supply
RS 232
RS 422
Analog
Analog
RS 232
Target Point
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Phase II
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Energy Management Maneuver
• Objective– To ensure the touchdown within CEP– Selected Fig-of-Eight Maneuver for altitude management– Length of leg is fixed considering turn time
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300kg p/p system
• Sluggishness response– No turn rate response up to 20% of differential command
• No aerodynamic rate derivative data• Model derived from flight data
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Challenges
• Design of Guidance and Control Scheme– catering to high wind– Payload mass variations
• Terminal Guidance for Soft Landing– Flight path can be influenced only with symmetrical deflection above 50% of
total deflection– Turn and altitude control cannot simultaneously done
• Sluggish Response– No Turn rate for command less than 20% of total command– Non-linear turn rate response against differential command
• Gain Scheduling– Measuring wind magnitude and direction– Air speed measurement