Affordable Sound Both for Voice Recording

Posted by Christoph Bartneck on Sep 1, 2017 in Design, Documentation | 0 comments

Recording a clear voice with no background noise is key for any video, audiobook or podcast. If you are limited in space and budget then you might consider building your own little sound proof voice recording box. I build this little gem from 6mm MDF and some acoustic foam taped to the box with double sided tape.

For the box you can create the drawing necessary for the laser cutter using online tools, such as Box Designer. It exports a PDF file which all the six faces clearly separated. If you are planning to make efficient use of your wood then you may prefer MakerCase. This service aligns the six sides so that they can be cut most efficiently from a piece of MDF. Here is the box drawing for laser cutter used for this design.

We attached rubber feed to the box and placed the microphone on an old mouse pad to isolate the microphone from any vibrations of the table, such as when a laptop is placed on it. Handles on the side allow for an easy transportation.

Here is a recording without the box. The microphone was placed just directly on the table:

This recording was made with the speaker sitting in front of the box speaking into the microphone.

The last example is with the speaker leaning into the box.

You will notice how all ambient noice is gone and how intimate the voice of the speaker sounds.

Bloomberg Businessweek interviewed Omics about my nonsense paper

Posted by Christoph Bartneck on Aug 29, 2017 in Featured, Research | 0 comments

Esmé E Deprez and Caroline Chen from Bloomberg Businessweek visited the headquarters of Omics in India to interview its owner Srinubabu Gedela about his company. Omics is widely considered a predatory publisher that publishes papers without rigorous peer review. Confronted with the acceptance of my non-sensical paper he replied that “Bartneck’s paper slipped through because it was submitted so close to the conference’s deadline.” Yeah, right.

Holonomic LEGO Mindstorms Robot

Posted by Christoph Bartneck on Aug 27, 2017 in LEGO, Project, Technology | 1 comment

A holonomic robot uses omni-directional wheels to drive and turn in any direction on the spot. Agilis is an example of an early LEGO holonomic robot. My model is much simpler and robust. Essential to all holonomic robots are the use of omni-directional wheel, such as the the ones from Rotacaster. I am using a compass sensor to allow the robot to be remote controlled on an absolute grid using Connexion’s Space Navigator. This 3D input devices can be mapped to the unique movements and rotations of a holonomic robot.

Tutorial on how to install and setup JInput on Mac OS X using Eclipse

Posted by Christoph Bartneck on Aug 14, 2017 in Documentation, Technology | 0 comments

3D LEGO Technic Connector

Posted by Christoph Bartneck on Jul 29, 2017 in Design, Documentation, LEGO | 0 comments

Connecting LEGO Technic beams in three dimensions remains a difficult task. While it has become easy to connect beams in one and two dimensions, it remains difficult to extend this to the third dimension.

I first designed a new LEGO Technic connector that features pins. The design was compact and stable, put the pins were too fragile. It was also very difficult to get the support material out from the holes.

My second design had no pins but still the option to firmly hold a technic beam. With this new 3D printed corner part it is possible to build a perfectly stable cube with a minimum of parts. The additional holes provide options for further strengthening the cube or to connect other parts to the cube.

The CAD model is available from Autodesk and GrabCAD.

Guide to LEGO ramp racing

Posted by Christoph Bartneck on Jul 20, 2017 in LEGO | 0 comments

Racing LEGO cars down a ramp is a popular attraction not only in the LEGOLAND Parks, but also at Brickshows and classrooms around the world. The physics around the race are well understood, but experiencing them in practice is a great learning experience for students.

We setup a little ramp race at home and I would like to share our setup and results with you. We put two base plates together as the ramp and inclined it at ten degrees. We then measured four meters from the starting point up the ramp to the finishing line.

Of course, you can race multiple cars at the same time but then you might encounter collisions and photo finishes too close to call. A reliable and precise measuring system is a much better solution. The SpeedClock App is just what you need. It allows you to measure the speed of a car with a smartphone. You can for example place the phone at the end of the ramp to measure the LEGO car’s maximum speed. You can also synchronize two phones running the app and measure between a start and finish gate. We tried both methods. All races were completed three times and the times and speeds reported are averages.

We started with a typical LEGO car (150gr) and it took it 4.42 seconds to complete the four meter distance. We then started to use my special Ramp Racer. It uses Mindsensor’s ball bearings, large wheels and a heavy battery pack (324gr). It’s maximum speed was 4.3 km/h and it took 3.4 seconds to complete the four meters distance. The same car without the batteries (148gr) had a maximum speed of 4.06 km/h and it took 4.2 seconds to complete the full track. Last we tested the Ramp Races with another set of wheels for which I also had rubber tires. With the rubber tires it took 3.7 seconds to complete the race and 3.6 seconds without.

In conclusion, the ball bearings make the car significantly faster and large hard wheels are best. The heavy batteries conserve the kinetic energy and result in a winning car. For a fair competition a maximum weight should be set. Since the ball bearings used were not from the LEGO company a policy on using third party parts is also advisable.

Easy LEGO Mindstorms Spirograph

Posted by Christoph Bartneck on Jul 18, 2017 in Design, LEGO, Technology | 0 comments

Ever since I created the Spirograph Automaton I remained interested in drawing machines. For this years Christchurch Brick Show I wanted a more compact, easier to build version of the Spirograph. This time I used three motors instead of just one. Controlling the speed of both arms and the table was very easy this way. The Spirograph worked reliably throughout the whole show. The MinuteBot baseplate makes the construction even easier. The building instruction are available for LEGO Digital Designer. More information is available at Rebrickable.