Posts tagged: stem

The Manipulator

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By stekgr, May 7, 2012 10:30 am

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Here a short explanation of one of the key components of the KiteGen Stem: The Manipulator

The “manipulator”, so nicknamed because its movements resemble the movement of a human wrist that controls the orientation and position of the kite from the top of the STEM. The distance between the two long antennas vary depending on the needs of the control software and its main function is to assist the take-off and landing manoeuvres.

In standby position, (with the kite hanging from the stem like a hammock) without the manipulator the kite tends to twist on itself and therefore blocking the take off manoeuvres, while keeping the antennas open it is easier to keep the kite open and aligned for the take-off. Taking off with the manipulator helps the air to be channelled in the kite and then closes with extreme speed. Once the kite is in the air the two antennas are closed and aligned to the Stem axis and its presence becomes imperceptible.

Each of the antennas is made in Kevlar/carbon and it is sensorised on 2-axis for the pull of the rope that passes through them. The system is capable to feel the forces in play and react in accordance to these inputs, so that in a situation with open antennas where the kite has just been launched, the pull of the ropes transmit a signal to the motors of the manipulator which react and closes automatically.
The two motors at the base of the stem manage the operating levers of the antennas through a long “push-pull” bowden system (similar to the mechanical principle of a bicycle’s brake). During the landing phase the system again spread apart the antennas facilitating the stability of the kite in its descent.

Lastly the sensitivity of the two antennas helps the whole system in terms of force control and positioning, similarly like the last portion of a fishing rod.

The manipulator, now in its fifth version, is a working reality of the concept idealized by M.Ippolito and reproduced in the model presented in various occasions

You can also download the video from here

KiteGen Model realized in 2008

Taking-Off, Flying and Landing in Safety

By stekgr, March 13, 2012 10:52 am

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You can also download the video from here

Taking-Off, Flying and Landing in Safety.

After many technological developments related to: the automatic take-off procedures, the controlled movement of the stem, the sensors installed and interlinked, radio bridges between the kite and land and many many other “hidden” aspects of KiteGen (each one essential as links in a chain), we are now proud to show the most visible achievement reached so far.

We are sure that this post is exactly what everyone was waiting to read from our blog. Testing activities on our prototype have started a few weeks ago and numerous technical achievements were collected. In one test in particular, Wednesday 15th of February, a successful take-off occurred with just 1.5 m/s of wind speed at ground (video link).

The KiteGen Stem has followed the procedures for the take-off through the “Swing” of the stem, allowing the kite to gain height thanks to the apparent wind generated by this movement (therefore, in this instance, without need of artificial wind as mentioned in the documentation). Once above the generator the kite gained more height finding stronger winds and completely unrolling the cables mounted on the drums for this test (300 m).

We know that the European average wind is around 3 m/s; with this exceptional result the KiteGen demonstrates that it has the freedom to take-off at any time, without aids for at least 5000 hours per year.

The test program will continue and evolve, in order to consolidate the results and check the behaviour of the generator during continuous flight; with the realistic ambition to get as close as possible to the 8760 hours per year of flight. (Although not always reaching full rated power during generation, the theoretical limit for this is just below 6000 hours, still 2-3 times the one of traditional wind farms).

The other obvious result that can be extrapolated from this post is that at least the beta version of the control software is ready. There is still a lot of work for the KiteGen team, however, we reached an important milestone in the estimated time, which suggests that the road is downhill from here.

Ropes completely unrolled (300m)

The KiteGen Stem buried in Snow

The research prototype KSU1 (also called mobilgen) already flew, and produced energy back in September 2006 (video link). This first experiment has allowed us to implement a long list of necessary features and upgrades to add on the industrial machine now under tests. Thus defining an appropriate technology architecture that would allow automatic take-off, manage the excesses of the wind bursts and reduce the wearing of mechanical parts, cables and kites. These specifications were designed and implemented and now are under constant test thanks to the completion of the world first KiteGen Stem.

In a nutshell these were the activities that, for those who follow the KiteGen project since the beginning, kept the KiteGen Team busy, while some impatience led some to criticise the project with statements such as “KiteGen is stopped because it does not fly.” The flight is certainly the most visible achievement but definitely not the only one reached by this company. Further updates will prove the immense work done and facts will convince the more sceptic.

From here the team will carry on as it always had, hopefully with more support, towards the ultimate goal:

Industrialize the first large scale machines that can exploit the huge potential of High Altitude Winds.

Keep up the good work.
Have a good flight KiteGen!

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