3D Modeling and Printing

3D modeling and printing can be easy if you have the right tools and programs. My experiences with the free Sketch Up Make and the Makerbot Replicator 5G printer are quite positive.

Getting started with 3D modeling:

Download and install Sketch Up Make (if want the program in a language other than english be sure to visit the webpage in the corresponding language) For example, http://www.sketchup.com/de leads to the German version.

Download and install the software for your 3D printer (in my case, the Makerbot desktop).


Sketch Up Make model of a gear from a Hexbug spider robot. Gears have been drawn with the Involute Gear plugin.

Start Sketch Up make. If you get an annoying prompt every few minutes, start sketch up make with administrator rights until the demo time for the Pro version is over.

Usually, 3D models are printed from an STL file, so you need to install the STL export extension. The extension can be found and installed via the extension warehouse. The extension warehouse can be found via the Window menu of Sketch Up. For accessing the warehouse extensions, you need to log in with a Google account.


Some models are kind of a fixer/upper: Netfabb/Microsoft’s model repair service

So far you can draw and export STL files.However, these files often suffer from model errors like inverted surfaces, holes, etc. In order to repair these problems, we recommend to run the STL file through the model repair service from NetFabb. The service is free for non-commercial use, but requires to sign in with a MSN ID to be used. Upload your STL there and download a repaired version (unfortunately there is no feedback what has been repaired).

Finally, open the STL with 3D printer software and hit print! Happy printing…

… and waiting hours for the printer to finish.

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Post-doctoral Fellow in Sensor Networks at ETH Zurich

           Post-doctoral Fellow in Sensor Networks
                        ETH Zurich

The research group on Computer Engineering at ETH Zurich (Swiss
Federal Institute of Technology) has an opening for a
post-doctoral fellow the field of sensor networks.


We have a long and successful history in sensor network research
and we are involved in several large-scale interdisciplinary
projects in environmental sensing. Our research combines
theoretical investigations with serious applications. Wireless
sensor networks are in operation at several field sites in high
alpine regions (permafrost research and early warning) as well as
cities (air pollution). In terms of basic research, our focus has
been on areas like synchronization, highly dependable wireless
protocols, network tomography, testing, formal verification
methodologies, formal methods, and energy harvesting.


The Computer Engineering and Networks Laboratory offers a creative
international environment, a possibility to conduct highly
competitive research on a global scale and to be involved in
teaching. The main responsibility of the position is to conduct
successful research in the field of sensor networks. There are
plenty of opportunities to cooperate with highly recognized
national and international partners. In addition, active
participation in research projects and leading a group of
highly motivated Ph.D. students is expected.


The candidate must hold a Ph.D. degree with top performance in a
field that is closely related to sensor networks. He or she should
have a track record in conducting original highly competitive
scientific research and publishing the results in top conferences
and scientific journals. Maturity, self-motivation and the ability
to work both independently and as a team player in local and
international research teams are expected. Interest in
interdisciplinary collaboration with environmental sciences as
well as outdoor proficiency is advantageous. German language
skills are not required, English is mandatory.


Deadline for application is the 31st of May 2014. Applications
should be sent by email to thiele@ethz.ch (Lothar Thiele). They
must contain a statement of interest, a CV, the names of two
references and additional documents, in particular copies of
degree certificates and the associated scores.

Useful links

 ETH Zurich: http://www.ethz.ch/en.html
 Department: http://www.ee.ethz.ch/
 Research Group: http://www.tec.ethz.ch/
 WSN Research: http://www.tec.ethz.ch/wsn.html
 Jan Beutel: http://www.tik.ee.ethz.ch/~beutel/
 Lothar Thiele: http://www.tik.ee.ethz.ch/~thiele
 Zurich: http://www.zuerich.com/en/Visitor.html

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Hacking Amazon’s Kindle E-Book Security with Lego Mindstorms

kindle-lego-device_sPeter Purganthofer, associate professor at the Vienna University of Technology, built an amazing project involving an Amazon Kindle, a computer with built-in webcam and a Lego Mindstorm robot.
The robot presses alternately the “next page” button on the Kindle ebook reader and the space button on the laptop. Thus, a computer program on the laptop takes a screenshot of the current page, which is subsequently converted into text using an OCR software. This way, one gets a DRM-free copy of an e-book “bought” at Amazon. Purgathofer states that due to Amazon’s e-book sales model, “The owner isn’t even an owner anymore but rather a licensee of the book”.

The video below shows the system in action. The overall machine is awesome. It reminds of designs for Rube Goldberg machines.

DIY kindle scanner from Peter Purgathofer on Vimeo.

Of course this is definitely not an efficient way to re-digitize an e-book. For example, the process could have been better automated using Kindle software and a screenshot tool directly on the computer. However, the goal was to make a noticable statement about copyright, eBook DRM and ‘ownership’ of eBooks. And to have fun playing with robots.

Posted in Hardware, Robotics | Tagged , | 1 Comment

Biologically Sound Neural Networks for Embedded Systems Using OpenCL


Guest post by Anita Sobe

Presenting our paper

I. Fehervari, A. Sobe, W. Elmenreich. Biologically Sound Neural Networks for Embedded Systems Using OpenCL. Proceedings of the International Conference on NETworked sYStems (NETYS 2013), Marrakech, Morocco, Springer 2013.

in the format of a short announcement was an interesting challenge. The task was to get the other researchers to read our paper by only talking about it for 5 minutes. Furthermore, the audience was wide-ranged from all topics of distributed systems. So, I had to introduce spiking neural networks and the motivation for using them on a distributed embedded system before pointing to the approach of implementing them with OpenCL:


Spiking Neural Network Model

Neural networks are widely used in machine learning and many implementations exist to process images, process information, etc. Biologically sound neural networks are more powerful than standard ANN models, because the encoding is done in a spike train, conveying also information in the time domain.

Thus, spiking neural networks have nice properties, but they require significant computing power to emulate them.


Example structure with 10x10x10 neurons. Typical structures are much larger requiring a high number of parallel calculations

For embedded systems, computation is a critical resource. We propose to use OpenCL for massive parallelization of the neural network model. OpenCL is a framework for programming software running on GPUs. But this is not enough, the most complex part comes from updating neurons and the state of the influenced neighbors. We therefore propose a connection model  where each neuron is only connected to its neighbors, up to a given hop distance. Using this model we were able to simulate 1 million neurons instead of 100.000 (which is big for usual networks). The performance gain is already excellent, but we even went further.

Performance gain

Performance gain

OpenCL supports local memory for so called task groups and a second-level shared memory for all tasks. Shared memory is slower, therefore, we redesigned the implementation in such a way that it only uses the local memory of OpenCL. This final measure improves the latency well enough to run our system with a high number of neurons on an embedded node such as a robot or a smart camera attached to a drone.

Posted in Embedded Software, Sensor Fusion, Uncategorized | Tagged , , , | 1 Comment

e-puck solving a maze

As a result from Rene’s and Kevin’s work, we can show a maze-solving application for an e-puck. The approach has been implemented on real hardware and tested in a simulation using Webots. To solve the task, different sensors of the e-puck (IR-Light Sensor, Distance Sensor, …) have been combined, so that the e-puck could solve this maze. The robot follows the right wall, until he finds its goal (a dark sector in the maze) – then the LEDs are blinking and it makes a sound, so you notice, it has finished.

As you can see in the video, the approach works (though the robot is moving a bit slowly); also the simulation predicts very similar results.

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Wireless Time-Triggered Communication using a Firefly Clock Synchronization Approach

In South-East Asia, huge swarms of fireflies synchronously emit light flashes to attract mating partners. The underlying principle can be used to implement a robust and scalable distributed synchronization approach in wireless sensor networks.


AVR Z-Link Zigbee Nodes

In this work we implement the Firefly Algorithm on battery-powered low-cost wireless nodes to establish a time-triggered network with a global notion of time. This global notion of time is used by the protocol but also provides a service that can be used by real-time applications. The synchronized nodes perform a time-triggered communication, where the sending instant of each message is known a priori to all nodes. This enables the implementation of an energy-efficient low duty-cycle protocol, where sender and receiver units can be turned off during silent phases.


R. Leidenfrost and W. Elmenreich. Establishing wireless time-triggered communication using a firefly clock synchronization approach. In Proceedings of the Sixth International Workshop on Intelligent Solutions in Embedded Systems, pages 227–244, Regensburg, Germany, July 2008.

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Call for Papers: Eleventh Workshop on Intelligent Solutions in Embedded Systems (WISES 2013)


WISES 2013 will take place in Pilsen (Plzen), Czech Republic on September 10-11, 2013.

Embedded Systems run our cars and telephones, control production lines and aircraft systems. Meeting the strong requirements regarding the cost, safety, security, size and the power consumption require new and innovative solutions. Providing flexible and configurable systems is nowadays the key role of the embedded software.

In this context, WISES2013‘s objective is to create a forum for exchanging ideas, discuss solutions and share experiences among researchers and developers from both industry and academia. Original papers describing prototype implementations and deployments of embedded systems are particularly welcome. WISES 2013 will be held in conjunction with the 18th International conference on Applied Electronics (http://www.appel.zcu.cz).

Topics of interest include, but are not limited to:

Embedded Systems Architecture

‐ Multicore SoC (e.g. homogeneous, heterogeneous MPSoC)
‐ Memory systems and optimization in embedded systems
‐ On‐chip buses and point‐to‐point networks
‐ Application‐specific (e.g. ASIPs, hardware accelerators)
‐ Architectures and tools for reconfigurable computing

Software for single or multicore embedded systems

‐ Applications and systems software (e.g. drivers, communication libraries)
‐ Real‐time operating systems and middleware in embedded systems

Prototype platforms, applications and case studies

‐ Next generation networking and mobile/wireless technology
‐ Sensor networks and related hardware/software platforms
‐ Embedded systems with ambient intelligence and pervasiveness

Tools and methodologies for analysis, exploration and validation

‐ Cost‐efficient and power‐aware embedded system design
‐ Fault tolerance, reliability and security in embedded systems
‐ Real‐time embedded systems
‐ Debugging and profiling techniques and tools
– Cyber-physical systems

Special Sessions:

‐ Industry‐oriented research
‐ Safety and Security
‐ PhD students session

Other special sessions can be proposed to the General Chairs.

Submission and Publication

The working language of the workshop is English. Prospective authors are invited to submit new original research papers of a maximum length of 6 pages (A4,two column, 10pt, IEEE conference style) for blind review. Initial submisssions must not contain any authors informations (name,affiliation, etc.)

All submitted paper will be peer-reviewed. Accepted papers will be published in printed proceedings. The papers will be made accessible via world-wide web and via IEEE Digital Library. Each paper must be presented by one of the authors at the workshop.

Submissions will only be accepted electronically via WISES homepage in PDF format. Submission will be enabled on March 11th.

Please format the final version of your accepted paper according to the “IEEE Manuscript Templates for Conference Proceedings” in A4 (latex or word): www.ieee.org/web/publications/pubservices/confpub/AuthorTools/conferenceTemplates.html

Important Deadlines and Dates

Manuscript Submission Final Deadline March 31th, 2013
Notification of Acceptance: May 31th, 2013

(download registration form)
(download copyright form)
August 20th, 2013
Camera-Ready Paper Submission: July 22th, 2013
Workshop: September 10th/11th, 2013
Posted in Embedded Software, Hardware, Protocols, Real-Time Networks, Robotics, Sensor Fusion, Simulation, Tools | Tagged , , , | Leave a comment