-Kipling
FPath is a project to explore the possibilities of the Feynman Path to Nanotechnology. Essentially this means using tools to make small tools which then make smaller tools. See the main FPath Project page for more details.
This experiment demonstrates the controlled motion of a movable red circle over a linear path drawn in the color green. One interesting thing about this experiment is that the green path does not physically exist. It is entirely virtual and is only drawn on the screen by the Walnut control software.
Also demonstrated is the ability of the moving object to lay down a virtual path as it moves along and later follow that path back to the start point. This mechanism is called "Graphical Stigmergy"
The target goal of this experiment is to:
Demonstrate the controlled motion of a movable red circle over a virtual linear path drawn in the color green. The green path is removed as the circle moves over it. As the red circle moves along, it can lay down a colored "trail" which forms a return path. When there is no more of the green path to follow, the red circle will follow the return path back to the start.
This experiment is intended to be part of a larger toolkit which will hopefully be useful in future Feynman path experiments. If the path of a tool head can be continuously corrected independently of the quality of the actuators - closed loop control in other words - then a lot of errors can be removed. This is important because as you have machines make smaller machines, the effects of errors compound.
The basic structure of the hardware is identical to that used in Experiment 003 but changes were made to the Walnut software. The starting point for this experiment is Walnut Server/Client version 00.02.05 and the changes made have been released as version 00.02.06.
The physical experimental apparatus uses various LEGO bricks extensively as the mobile apparatus. See the separate documentation of the Steggo Project and the discussion in Experiment 003 for more information.
Below is a specific list of the steps involved in reaching the goal. All of these steps are discussed in considerably more detail in the video which documents this experiment.
The experiment was successful. A red circle mounted on the tool head of a motorized XY axis will follow a virtual green path to the end. The green path is removed as the red circle travels over it. An optional cyan colored path can be laid down as the red circle moves and the algorythms can then use that path to return to the start point.
Algorythmically, indirect coordination via the modification of the environment is called stigmergy. Interestingly, this is the way ants find their way about. As ants wander around they leave a trail of scent. When they want to return, they just follow the scent on the way back. Other ants can follow the same trail and they too will leave their scent. The stronger the scent, the more ants that will follow it so you can get lines of ants following a complex path to and from a food source - all without any central planning or control.
Since this behavior is called stigmergy when ants do it. I think I will refer to this particular technique as "Graphical Stigmergy".
This experiment was also discussed in a post on the RepRap Blog: Graphical Stigmergy
This experiment is now complete. The Walnut software associated with this experiment can be found under Commit ID: ae0b457 on the GitHub repo.
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