Novel Machine Vision Solution For Determining Kite State
Minute changes in kiteline angle and line curvature at the surface
deterministically reflect the position, orientation, velocity, and pull of
a kite aloft. Crude mechanical line-position encoders are common on
AWES-developmental platforms, but prone to damage and uncertainty
(especially during transient line slackness). Elaborate multisensing at
the kite [wing of the kite
system] is commonly specified to avoid the uncertainty mechanical
encoders suffer from. A separate line-tension sensor is usual. A better
line-encoding method is needed to help resolve kite state.
To adequately monitor kite state for control purposes, it may suffice for
kiteline geometry at the anchor point to be closely imaged within a dark
fabric "boot" by stereo micro video (or
by micro laser scanner). The kitelines in the boot would be artificially
lit for an easily processed image. A stereo-pair requirement could be met
with just one camera and mirror(s) in the view field.
The system could be sensitive to events that mechanical encoders miss.
Even twisted-line states can in principle be disambiguated by this
sort of close videogrammetry. A look-up table (database) of local line
states would output the detected kite state. Markov chains, Bayesian
inference, or model predictive control could interpret and act on this
To complete a minimalist sensor suite, an encoded reel can keep track of
line length. Acoustic monitoring of line noise could be a semi-redundant
data source (topic for a separate post). Avionics on the kite remains an
option, working even better without mechanical line-encoder uncertainty to
worry about. Meteorological sensors and METAR data would be a given,
helping factor out hodographic twist, for example. A simple limit
switch/sensor could react to, or confirm, a kite returned to a cradle.
The proposed machine-vision kite state detection method would be immune to
many normal failings of outdoor vision systems, such as sun glare, night
lighting, fog, and bird droppings or raindrops on a lens. It would
eliminate the inherent flaws of mechanical line position encoders. It
could be an ultimately cheap solution as well.
Comment and development of this topic will be occurring here.
All, send notes, links, drawings, and photographs!
- Terms and aspects:
- kite state, kite states [[Often a
writer will mean kite-wing-set state when writing "kite state"
in discussions. As a kite is a combine of wing set, tether set, and
resistive or reaction set, then kite state would include the state of
the wing set, tether set, and anchor or reaction set. Look to context
to note if the author is with a focus just on the wing set of a kite
- wing-set state
- tether-set state
- resistive-set state
- wiki: Hodograph
- machine-vision kite state detection method
- Related links and concepts:
- Commentary is welcome: