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 2 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

09 June 07 Workshop on Mathematical Engineering 3 CADS Name Controlled Aerial Delivery System Objective To demonstrate the technology for precise delivery of a payload of 500 kg using a Ram Air Parafaoil

09 June 07 Workshop on Mathematical Engineering 4 Airborne Guidance &Control System` Task To 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

09 June 07 Workshop on Mathematical Engineering 6 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

09 June 07 Workshop on Mathematical Engineering 7 Ground based Guidance and Control System Architecture Analog RS 232 On-Board Sub-Systems PFCC BL 2120 Actuators GPS Receiver Alt. Sensor Heading DRU NMEA Tx,Rx Pt & SB Lanyard Commands Ground Sub-Systems Joy Stick Issues Vehicle state information Sensors Mounting Sensors selection

09 June 07 Workshop on Mathematical Engineering 8 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

09 June 07 Workshop on Mathematical Engineering 9 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

09 June 07 Workshop on Mathematical Engineering 10 AG&CS Architecture Para Flight Control Computer On-board DRU Heading Sensor GPS Antenna IAS Transducer Altitude Transducer Proximity Sensor Port Lanyard Actuator Starboard Lanyard Actuator Handheld Terminal TX/RX  C BL 2120 Parachute Power Supply RS 232 RS 422 Analog RS 232 Target Point

09 June 07 Workshop on Mathematical Engineering 11 Phase II

09 June 07 Workshop on Mathematical Engineering 12 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

09 June 07 Workshop on Mathematical Engineering kg 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

09 June 07 Workshop on Mathematical Engineering 14 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