Free software robotic arm

13 Jun 2009

Industrial robotics still is dominated by proprietary “off-the-shelf” solutions. It is very common to find that a single robot is controlled by several unrelated software products which do not interoperate with each other. Furthermore the control PCs are running Windows XP which is scheduled using a hardware task switcher and the VxWorks software. Basically the situation is a set of hacks which reflects the political situation of the marketplace rather than the demands of the technical problem at hand.

The situation is very reminiscent of medieval guilds. The medieval guilds were small communities (companies) where an apprentice had to stay with a master for many years to get inaugurated into the secrets (intellectual property) of the trade. The career options were extremely limited since the guilds had the exclusive right of selling products on the market (OEM deals). After many centuries of moderate progress, industrial mass production and global trading finally swept away the rigid guild system. But I am digressing.

There is a real opportunity for a robotic company to make a difference by simply providing documentation and free software along with their product. Neuronics in Switzerland is maybe the only company currently targeting the industrial market with an industrial precision (0.1 mm) robotic arm which comes with free software and documentation. The product is called Katana. The Katana robot arm can carry 400 grams and it can be controlled using TCP/IP (i.e. XML-RPC) and the client library. The robot’s API supports point-to-point operation, customisation of speed and acceleration, as well as spline-motions in configuration space. There also is a native API for programming the control board directly and finally there is the source code of the control software itself.

Neuronics is located in Zürich and there is potential for a collaboration with local universities.

See also:

Obama speech at National Archives

21 May 2009

Click on the picture to watch the video at The Huffington Post.

The Whitehouse website provides an article as well as the transcript of the speech.

Update:

A video of the speech is now available from the Whitehouse website itself

20090521_Protecting_Our_Security.mp4 (536.9 MiB)

Public media is deeply concerned that the current US government is lacking commitment to stop the unconstitutional practice of prolonged detention.

Also see PBS-documentary: Bush’s War.

Update:

The video is now only on Youtube.

The Hunt for Gollum

03 May 2009

Today the fan film The Hunt for Gollum was released on the web. The film premiere is at Sci-Fi-London. The 40 minutes film was created by volunteer actors and artists in UK and it even includes some computer graphics.

The scenery of London, Essex, Wales and Epping Forest served as a replacement for Middle Earth. The scenes with the nice wheather were generated by Stefan Menzel in Sheffield using the Terragen software.

If this is not enough, there is another upcoming fan film called Born of Hope coming out autumn this year.

Avoiding alias_method_chain in Ruby

09 Apr 2009

I currently use Ruby a lot but since I am not into developing web applications, I am not knowledgeable about Ruby on Rails. So when I watched Yehuda’s presentation about refactoring Rails I watched it not so much because of Rails but because of refactoring Ruby software.

Yehuda talks about introducing modules to be able to use super instead of alias_method_chain. I tried it out on an example and it seems to be a really useful thing to know.

Using alias_method_chain

This approach uses the popular definition of alias_method_chain

class Module
  def alias_method_chain( target, feature )
    alias_method "#{target}_without_#{feature}", target
    alias_method target, "#{target}_with_#{feature}"
  end
end

As an example we have a class Test with a method x

class Test
  def x
    'x'
  end
end

Using alias_method_chain the method x can be extended without having to introduce a new inheriting class

class Test
  def x_with_two
    "#{x_without_two}2"
  end
  alias_method_chain :x, :two
end

The method now exhibits the new behaviour

puts Test.new.x
# "x2"

Using modules

However the method x can be declared in a module which is included by Test

module X
  def x
    "x"
  end
  module_function :x
end
class Test
  include X
  public :x
end

Overloading the method now can be done by including another module which has a new definition of x. The new method x can invoke the previous one by calling super

module X2
  def x
    "#{super}2"
  end
  module_function :x
end
class Test
  include X2
end

The method now exhibits the new behaviour

puts Test.new.x
# "x2"

The issue with this approach is that overloading of the method needs to be anticipated. However at the same time the code indicates it more clearly that the first definition of x is not necessarily the final one in objects of type Test. Moreover this approach works without public definitions of methods you are not supposed to call (e.g. x_without_two).

Update: If you like to see another talk from MountainWest RubyConf 2009, you should check out Jim Weirich’s talk on The Building Blocks of Modularity.

Openmoko discontinued?

05 Apr 2009

Translation of Vorläufig kein weiteres Linux-Telefon

Not another Linux-Phone

by Mathias Born. Updated 02.04.2009

Bad news for libertarians: Openmoko suspended development of the GTA03 smartphone until further notice and laid off part of its staff. The managing director said that this would be the only way for the company to survive in the long-term.

For the time being Openmoko abandons development work on the next generation of the current Freerunner smartphone. Furthermore the Taiwanese company releases almost half of its staff. This is what Openmoko managing director Sean Moss-Pultz said today at the Opensource trade show “Openexpo” in Bern. Partially the staff had been given notice; partially the staff had resigned voluntarily. “We have arrived at a critical point”, said Moss-Pultz. “This measures are absolutely necessary to even stay in business.”

Openmoko’s aim was ambitious: The subsidiary of the Taiwanese component manufacturer First International Computer (FIC) wanted to produce an Opensource-Smartphone. The source code was supposed to be freely available as well as the drivers and the specification of the components. Therefore software developers can reprogram the mobile phone at will. So far the company has produced two devices; the first one as a series of 3000 samples, the second one having been sold 10’000 times so far. Both are targeted at developers. The project was experiencing difficulties from the very beginning: The launch dates were postponed. Some batches had design faults. Furthermore there was a change in staff, which delayed development. At the middle of this year the software should have been stable enough for allowing the phone to be used in every day life.

Plan B

Openmoko now focusses on “Plan B” according to Sean Moss-Pultz. “For business reasons we have choosen the second device which we have in our pipeline.” He would not be free to disclose any more details. However it would not be about a telecommunication device. In contrast to the smartphone the first version is going to already target the mass market. Also this product is going to be developed with Opensource software he assured.

The development of the software for the Openmoko-Smartphone would continue said Moss-Pultz, however with less resources. Therefore he places great hope on the community. “Buy a Freerunner, help to fix the bugs and write new programs” he appealed to his audience during his presentation at the Openexpo. He hopes to also use those lateron on a new device. “Also in the future we want to produce mobile phones.” (Berner Zeitung)

Also see

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Jan Wedekind