Tuesday, 3 February 2009

Careful with that axe, you genius

To paraphrase PJ O’Rourke, only God can make a tree: but only man can cut them down in the time it takes to read this post.  See:

What a wonder!  As a steam shovel is to a spade, this device is to an axe. [Hat tip Noodle Food]

It’s devices like this that increase living standards and raise real wages.  Yes, it’s true.


  1. This comment has been removed by the author.

  2. That is awesome, but the title of the post is even better. :)

  3. Not sure who manufactures this particular machine, or where it is manufactured, but such a machine has for some years been manufactured, mostly for export, by a company named Waratah in Tokoroa,NZ.

  4. Wow! That is engineering control in its finest design and I do know the control algorithm that is used in the design. I am pretty much sure that it is.

    Watching the swinging of the part that does the cutting I noted that it is flexible, which is free to tilt and swing at any angle in 3D. The swing follows/chases the weight (center of mass) of the log so as to minimize its swing angle's amplitude which can cause instability in the machine's operations or even failure if not controlled properly. I noted that the swing self-adjusted itself (ie, keep tilting towards the direction that would minimize the amplitude) even when the operator of the machines keep moving it around.

    The same control design is used in large cranes operating in wharfs or highrise buildings. It would be quite damaging for the crane's operations if the load's swing is not minimized (or controlled properly).

    This swing-type problem is known in Physics/Engineering as the inverted pendulum which is a highly non-linear phenomena in 2D movement, but even it is more complex in 3D movement, which is what this machine does.

    There are many examples on youtube for inverted pendulum demonstration using robots, but I find this one interesting:

    Inverted Pendulum Balancing Robot Montage

    Perhaps, NASA warmist Dr. James Hansen might want to visit their own Jet Propulsion Laboratory control lab at CalTech and talk to those engineers of how to model non-linear feedback control system properly, because the now outdated linear control model he proposed for climate dynamical system have been found out to be full of bullshits (hugely in disagreement with observational data).


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