1 1 The Laddermill - Design, Building & Testing Bas Lansdorp Richard Ruiterkamp Background Kite...
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Transcript of 1 1 The Laddermill - Design, Building & Testing Bas Lansdorp Richard Ruiterkamp Background Kite...
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The Laddermill
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Design, Building & Testing
Bas LansdorpRichard Ruiterkamp
Background Kite control mechanism Groundstation Electronics Testing
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Agenda
Background
Kite control mechanism
Groundstation
Electronics
Test plans
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Kite control mechanism
Types of wings
Surfkites
Rigid/inflatable kites
Cloth kites
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Kite control mechanism
Background Kite control mechanism Groundstation Electronics Testing
Early concepts
Drag flap control Wingtip AoA control
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Kite control mechanism
Background Kite control mechanism Groundstation Electronics Testing
Tow point control
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Kite control mechanism
Background Kite control mechanism Groundstation Electronics Testing
Lightweight
Sand proof
Strong
Successful?
What can go wrong, will go wrong
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Laddermill 2 kW groundstation
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Laddermill 2 kW groundstation
Slipping occurs
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Laddermill 2 kW groundstation
•Cable is on the drum under low tension, low stretch
•Cable is pulled off under high tension, high stretch
•This means that a larger length of cable leaves the drum, than is actually on the drum!
•Slip occurs over a certain angle, about 1 revolution
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New laddermill 4 kW groundstation
•Rotating platform: cable always straight
•Traversing train: cable always in the middle of the platform
•Very large drum: only a single layer of cable during energy generation (Drum 1 m wide)
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New laddermill 4 kW groundstation
Background Kite control mechanism Groundstation Electronics Testing
Who will help us?
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New laddermill 4 kW groundstation
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New laddermill 4 kW groundstation
Instead of the rotating platform, the rotation can be placed on top of the traversing drum.
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New laddermill 4 kW groundstation
Testing:
•4 kW groundstation not tested yet
•Force of the kite: ~1500 N
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New laddermill 4 kW groundstation
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Electronics
Main computer GUIManual Input
Flight Computer Servo controlFlight sensors
Manual override
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Electronics
Manual Input
• Main computer program• Allows manual input from joystick/keyboard• Control input directly send to flight computer• Logfile created for all input/output• GUI allows graphical representation of kite in flight data such as apparent wind speed, position, altitude, heading
Main computer GUI
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Electronics
Flight Computer Servo controlFlight sensors
• Flight computer receives servo commands from ground computer• Sensor package: - altitude (abs. pressure)
- apparent wind speed (diff. pressure + pitot tube) - Servo current consumption - XYZ acceleration (accelerometers) - Gravity vector direction (accelerometers) - Position/heading (GPS module) - Visual data (web-cam)
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Electronics
Flight Computer Servo control
• Servo signal (PWM) generated by slave u-processor• Pilot take over switch allows overruling flight electronics in case of failure• Flight sensor data is polled and compressed before sending package• max. 20 km range (current version 5 km range)
Manual override
Flight sensors
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Electronics
Transceiver unit
Ethernet and USB ports
Embedded PCRunning Linux
Altimeter and pitot diff.pressure sensors
XYZ accelerometer
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Testing
Load cell assembly for measuring line tension vector
Low stiffness beam
Load cell
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Testing
Setup for kite testing:•Line connected to load cell sensor•2 lines to the kite, connected to control mechanism
Interesting tests:•cl and cd vs. AoA and wind speed•Static and dynamic stability•Response of the kite control mechanism•Flying patterns
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Testing
cl and cd vs. AoA and wind speed•Put kite at the zenith position•Keep kite steady by computer•Test various AoA at different wind speeds•Measure L and D to determine cl and cd
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Testing
Static and Dynamic stability•Put kite at the zenith position•Keep kite steady by computer•Give various types of input and look at the response•Measure position by the load cell
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Testing
Response of the kite control mechanism•Put kite at the zenith position•Keep kite steady by computer•Give various steering inputs and measure accelerations
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Testing
Check what happens during pattern flying•Put control at certain location•Measure the tension in the line•Compare with same tow point position and same wind speed at zenith
Tension the same, AoA the same?
Background Kite control mechanism Groundstation Electronics Testing