Tuesday, September 22, 2015

Building a Rope Bridge With Drones

Published on Sep 18, 2015
Building a rope bridge with flying machines in the ETH Zurich Flying Machine Arena.

The video shows quadrocopters autonomously assembling a rope bridge. This is part of a body of research in aerial construction, a field that addresses the construction of structures with the aid of flying machines.

In this work, a rope bridge that can support the crossing of a person is built by quadrocopters, showing for the first time that small flying machines are capable of autonomously realizing load-bearing structures at full-scale and proceeding a step further towards real-world scenarios. Except for the required anchor points at both ends of the structure, the bridge consists exclusively of tensile elements and its connections and links are entirely realized by flying machines. Spanning 7.4 m between two scaffolding structures, the bridge consists of nine rope segments for a total rope length of about 120 m and is composed of different elements, such as knots, links, and braids. The rope used for these experiments is made out of Dyneema, a material with a low weight-to-strength ratio and thus suitable for aerial construction. Of little weight (7 g per meter), a 4 mm diameter rope can sustain 1300 kg.

The vehicles are equipped with a motorized spool that allows them to control the tension acting on the rope during deployment. A plastic tube guides the rope to the release point located between two propellers. The external forces and torques exerted on the quadrocopter by the rope during deployment are estimated and taken into account to achieve compliant flight behavior. The assembly of the bridge is performed by small custom quadrocopters and builds upon the Flying Machine Arena, a research and demonstration platform for aerial robotics. The arena is equipped with a motion capture system that provides vehicle position and attitude measurements. Algorithms are run on a computer and commands are then sent to the flying machines via a customized wireless infrastructure.

In order to be able to design tensile structures that are buildable with flying robots, a series of computational tools have been developed, specifically addressing the characteristics of the building method. The design tools allow to simulate, sequence, and evaluate the structure before building.

The location of the scaffolding structure is manually measured before starting the construction. The primary and bracing structure can then be realized without human intervention. Before realizing the stabilizers, the locations of the narrow openings of the bridge are measured and input to the system, which adapts the trajectories accordingly.

More information and related publications can be found on the project website:

Related roboHub article: http://robohub.org/watch-flying-machi...

* Credits
Aerial construction is a collaboration between the Institute for Dynamic Systems and Control and Gramazio Kohler Research at ETH Zurich, Switzerland, 2015

* Researchers
Federico Augugliaro, Ammar Mirjan, Fabio Gramazio, Matthias Kohler, and Raffaello D'Andrea

* With contributions from
Maximilian Schulz, Marc-Andrè Corzillius, Michael Egli, Gregy Huber, Timon Winkler, Emanuele Zarfati, Mina Kamel, Gregory Bättig, Alexander Selwa, Evan Wilson, and Augusto Gandia

* Location
ETH Zurich, Flying Machine Arena - http://www.FlyingMachineArena.org

* Acknowledgments
This work is supported by and builds upon prior contributions by numerous collaborators in the Flying Machine Arena project. Seehttp://www.flyingmachinearena.org.
This work was supported by the Hartmann Müller-Fonds on ETH Research Grant ETH-30 12-1 and by the SNSF (Swiss National Science Foundation).

Saturday, September 19, 2015

iRobot Roomba® 980- The iRobot® Entire Level Challenge

Published on Sep 16, 2015

Monday, September 7, 2015

Man Hooks Up 54 Drones To Lawn Chair and Flies To Maker Heaven!

Published on Aug 29, 2015
The Swarm man carrying multi-rotor airborne flight testing montage. 54 counter-rotation propellers, six grouped control channels with KK2.15 stabilization. Take off weight 148kg, max lift, approx. 164kg. Endurance10 minutes. Power approx. 22KW.

Just a bit of fun for my self, never intended for making a significant journey or flying much above head height. Approx cost £6000.

Props at 18 in were the largest I could find with contra rotating pitches and so defines much of the layout. Also the fine pitch allows them to turn at high speed which reduces motor weight for a given power. Motor KV chosen to work with 4 cell batteries with 20% or so control margin. This low margin maximises the ESC efficiency, higher margin results in higher circulating current losses in the ESC and motor, reducing endurance.

54 chosen as this fits the hexagonal close pack layout. 6 more could be added in the centre. 18 in props at 5000 rpm though hazardous, are still much less so than 6, 5 ft ones. Where could you get a low power 5ft prop from weighing less than 1Kg with opposite pitches? The 54 gives good redundancy as mechanical and power electronic systems are the main failure areas. I have had one ESC randomly fail already. Controls could be made fully redundant (9 x KK2.15s) so only the control sticks (and pilot) are single failure points. Redundancy increases the likely hood of failure but reduces the consequences.

Props are standard RC aircraft types used at a relatively low fraction of their thrust/rpm capability. So should be reliable though needlessly heavy. Being inline with my head the polycarbonate dome is for protection. The polythene bubble balloons up catching some ground effect pressure rise contributing to lift. It also doubles as a rain shelter...

Batteries, ESC and motor are close together to minimise wiring weight which is significant because of the high current 30A. Also the battery damps vibration. Individual batteries does mean some may run down a little quicker than others. The front and rear groups are used for pitching, a more common manoeuvre so far than roll.

No one has spotted the biggest flaw! That is the large number of props running at high speed means the net torque reactions are relatively low, so the craft has little yaw authority. So it probably needs a tail rotor for spot turns.

Sunday, September 6, 2015

Videos: Awesome New Star Wars Droid You Control With Your Phone! BB-8 App-Enabled Droid || Built by Sphero

Spheero just came out with an incredibly cool new Star Wars robot based on the BB-8 Droid from the upcoming movie.  I gotta get me one of these.  Here's What Wired Magazine says about it:

 "the big-ticket item—the one that has already been reported sold out in Tokyo—isn’t from Hasbro, Mattel, or Lego. It’s an app-controlled miniature robot of BB-8 created by robotics company Sphero."

BB-8 App-Enabled Droid || Built by Sphero

Star Wars The Force Awakens BB-8 Toy Teardown

Sphero's Star Wars BB-8 Droid | Demo