Featherweight Schnauzer Part 18

Quite a lot of time has past since the last update about the status of my featherweight combat robot Schnauzer but finally there is some progress to report. Building a combat robot one can clearly observe Pareto's Law in action. Parato's Law simply states, that 80 % of the result can be achieved with 20 % of the effort. However, the flip side of this rule implies that finalising a project (doing the last 20 % of the work) will consume 80 % of the effort. And with a combat robot, you do want to go for the 100 % solution because everything else might leave you with a pile of rubbish in the arena. That being said I'd like to switch to the main purpose of this post which is to describe the latest updates on Schnauzer.

In the new version of Schnauzer only its rear wheels are directly powered by electric motors. The front wheels are powered by toothed belt which transmits the power from the rear wheels via an cogged-belt pulley(s) and tooth belt to the front wheels. This can clearly be seen in the next picture which displays the drivetrain of the left side of the robot.

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In the picture above the considerate reader might have observed some shiny things at 1/3 and 2/3 of the lower tooth belt. Those are DIY deflection sheaves built from ball bearings. Their purpose is to lift the tooth belt up and over an angle bracket which is connecting the base plate with the hardox (side and front) armour.

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Unfortunately the purchased tooth belt was a bit too long and therefore is not sitting tense enough on the two cogged-belt pulleys. Loss of traction in the heat of combat might be result. In order to circumvent this the design of a tooth belt tightener was necessary. The tightener was designed utilzing Autodesk Fusion 360 which is a very powerful tool and also has a startup license 🙂 Here is the finished design:

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Upon completion of the design process I called up my reliable supporter of 3D prints and sent the design files to him. On the next picture you can see the printed belt tightener (well the part that is printable at least).

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The next step was to insert the belt guide (which will later on press against the tooth belt) which consists of two ball bearings plus three washers. The tooth belt tightener is supposed to be mounted on the top plate of the robot facing downwards. When the top plate is closed and firmly connected with the rest of the robot the belt tightener should press against the tooth belt and  eliminate any belt play.

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Next up: Integration with Schnauzer and finalizing the top plate (need holes for screws, removable link, ...).

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Dornier Museum Friedrichshafen Part 2

In my last blog article I was discussing the Dornier Museum in Friedrichshafen, with the main focus on the VTOL transport jet plane Dornier Do31. However, the museum contains many other interesting exhibits which I would like to share with you.

Dornier Do B Merkur: This plane was designed as a passenger plane which could pack up to 8 passengers plus a crew of 2. A BMW V1 engine with 680 PS allowed for an maximum airspeed of 175 km/h. The Dornier Merkur had a range of up to 1000 km. Its virgin flight took place on February 10th, 1925.

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Dornier Do J Wal: The Dornier Wal was the most successful flying boat developed by Dornier. More than 250 pieces of this machine were built whose prototype Dornier Do Gs I virgin flight took place on July 31st, 1919. Two six zylinder Maybach Mb IVa engines with 260 PS each were used in the  Dornier Do Gs I to power two propellers with a diameter of 3 m.

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Due the treaty of Versailles and because the airplane had a advanced concept the allied forces demanded extradiction of the plane. In order to avoid handing over the plane it was sunk in the Baltic Sea on April 25th, 1920. To circumvent further problems with the treaty a construction office in Italy (Marina di Pisa) was founded were the successor Dornier Do J Wal was developed.

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Interesting fact: On May 21st, 1925 the polar researcher Roald Amundsen started with two Dornier Wal planes from Spitzbergen towards north pole. On plane had to perform an emergency landing due to motor problems. The other plane was landing too and suffered severe damage. The researchers repaired the first plane (and a runway, which took them 3 weeks) and managed to fly out to the north coast of Spitzbergen where they were rescued by a sealer ship.

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Dornier Do 28 Skyservant: The Do 28 was a reliable dual-engine plane mainly used by the german armed forces and possesed STOL capabilities. During the whole 20 years time of service within the german military only 3 planes (out of 121) were lost.

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Dornier Do 29: The Dornier 29 was developed during the 1950s as an experimental platform for testing a tilting-propeller system for STOL aircrafts.

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Two planes of the Do 29 were built and the virgin flight of the first prototype took place on December 12th 1958.

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During testing the new aircraft concept with two tiltable pusher propellers proved highly successful and allowed for a stall speed of only 24 km/h.

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Despite this great success the aircraft was not pursued further at the end of the flight test program.

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Only one of the two Do 29 prototypes survived the program and is now exhibited at the Dornier museum in Friedrichshafen.

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Alpha Jet: The Alpha Jet was the result of a cooperation of the Dassault Aviation (France) and Dornier. The plane was intended as a light attack jet and advanced trainer aircraft. A total of 480 planes were built and the plane was used in the air force of several countries e.g. French Air Force, Belgian Air Component, Cameroon Air Force, Royal Thai Air Force, Portugese Air Force.

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Dornier Do33 KAD: The Do33 KAD was developed as a reconnaisance drone which could penetrate up to 150 km of enemy territory while flying at Mach 0,85.

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Various sensor payloads could be used with the drone such as an optical camera, a infrared line scanner and a high resolution side-looking-airborne radar.

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Dornier Do 34: The Dornier Do 34 Kiebitz was designed as an unmanned military reconnaissance drone.

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Dornier Zieldarstellungsdrohne: The drones pictured below served to simulate a target for interceptor planes and anti-aircraft artillery.

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The drone is powered by a gasoline engine and resembles modern drone designs quite eerily.

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Bachem Ba349 "Natter": The Bachem 349 was a world war II german rocket powered interceptor which was designed to prevent the devastating bomber attacks of the allied forces against german industrial plants. To my best of knowledge it has no connection with Dornier and the reason behind its exhibition in the Dornier museum remain a mystery to me. However, it was great to see this very unconventional plane whose design reflect the desparate situation of the german army by the end of world war II.

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Dornier Museum Friedrichshafen Part 1: Do31 VTOL

In the beginning of september I went on a little vacation which also took me to Friedrichshafen on the Lake Constance. Friedrichshafen has gathered quite some fame for being the birth place to the legendary Zeppelin lighter-then-air airship. But Friedrichshafen was also the birth place of the company Dornier. It was founded by Clause Dornier who started out as an engineer working for Ferdinand Graf von Zeppelin. His ingenuity soon led to his promotion to leading his own department ("Department Do") within the Zeppelin company where he was responsible for developing heavier-then-air airplanes. During those times he was responsible for the creation of many of the flying boats many people associate with the name Dornier (such as the 12 engine plane Do X). However, the companys spirit of innovation went beyond flying boats. One of said innovative creations is the Dornier Do 31, the only transport jet airplane amongst all aircrafts with VTOL (Vertical Take Off and Landing) capabilities. And one of those beauties (only three were built in total) is located in front of the Dornier Museum in Friedrichshafen.

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The Do31 needs a crew of 2 persons and has a transport capacity of up to 36 soldiers. The length of the plane is 20.53 m with a wingspan of 18 m. The plane has a loaded weight of 22453 kg and carry a payload of up to 3600 kg.

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The cruise speed of the Do31 is 650 km/h but it can go as fast as 730 km/h. With maximum payload onboard the plane has a range of 1800 km and can climb to up to 10700 m.

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Bristol-Siddely developed the Pegasus 5-2 as main engine for the Do31 which is basically a vectored-thrust turbofan engine where the resulting stream can be directed downwards via four rotable outlet nozzles. Interesting side note: Those engines were lated used for the Harrier VTOL figher jet.

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However, those engines were not enough to lift the heavy plane. They were supported by a total of eight Rolls-Royce RB162 lifting engines with four of them being mounted in a casked at the end of the wing on each side.

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When the Do31 wanted to perform a vertical take off (or landing) manoveur the rotatable outlet nozzles were rotated in dowards position and the lifting engines in both wing-end caskets were started (also the air inlet and stream outlet had to be opened - on all pictures those hatches are closed).

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A sophisticated flight controller was developed to support the pilots in the hovering flight mode and while transitioning from hovering to normal flight.

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The maiden flight took place on February 10th, 1967. Back then there were no powerful digital processors or computers available like we have now to our disposal. In order to be able to deal with the complex mathematical problems related to an VTOL aircraft design Dornier developed the hybrid computer Do-960 which consists of digital and analog circuitry.

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Unfortunately the project was cancelled in 1970 for various reasons. One of those factors was that the lifting caskets produced a huge drag and added quite some weight to the airplane. This in turn led to a reduced payload and range in comparison to an conventional aircraft.

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Last but not least: Some videos to feast your eyes upon 🙂

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LXRobotics at the Robotour Deggendorf 2016

Hi everyone! I realise that I haven't published a blog post in a long time - This is mostly due to the fact, that many developments are not ready for prime time yet and not because there is nothing going on 🙂 Despite the lack of LXRobotics related news I can tell you a bit about a annual robotic competition called Robotour which took place in Deggendorf / Germany on September 17/18 2016.

The purpose of the competition is to develop autnomous robots which can find their own way to a given set of GPS coordinates. The event takes place outdoors and therefore the robots need to be 100 % weatherwaterproof. The event is organized by the team behind http://robotika.cz/en and further information about the rules can be found on their website. Some of the competing robots are presented below. If anyone has more detailed information on the robots or the competition please do not hesitate to send me an email.

Team Cogito

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Team KaMaRo Engineering (Karlsruhe / 2nd place):

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Team Istrobot (1st place)

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AmBot

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Team JECC / Fesl JECC has participated with two robots at the event. The robot Fesl (pictured below) won the respectable 3rd place in the competition. It is equipped with GPS, stereo cameras, laser scanner, inertial measurement unit and uses neural networks to detect traversable paths as well as obstacles.

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Picture of the Fesl's main screen while setting the robot up for the competition.

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Picture of the Fesl's main screen in active driving mode.

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The next picture shows the setup of all robots before the start. It was raining heavily 🙂 All robots were placed in a line where the slowest robots were located in the front and the faster robots were located in the back. 10 minutes before the start target GPS coordinates + a specific start time are given out by the organizers to the competing teams. Those coordinates have to be entered into the robot control system. When the start time is reached all robots should automatically start to navigate towards their goal. Note: The little robot on the left bottom corner of the picture also belongs to Team JECC.

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The start! I expected screeching tires and fast driving robots but in reality it was rather slow. Some robots even drove in the wrong direction 🙂 - Before laughing too loud one shoud consider the complexity of the task, the heavy rain and the fact, that all robots were built by hobbyist's. Since I have built a number of robots myself I know how much work one has to put into such a project.

Let's get back to the competition: After some hesitation the robot of Team Kamaro took over all the other robots on the left and drove far ahead of the pack. The complete competition consisted of four runs and the distance driven towards the target GPS coordinates while each of those runs was accumulated. The winner was selected based on the total distance travelled. Touching another robot immediately disqualifies the robot from the current run.

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Last but not least: A short video showing a bit of the third round of the Robotour 2016 in Deggendorf:

If you are hungry for more videos please feel free to check out this playlist.

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