Polo Target Surface

This page should clear up any uncertainties about MARCO's target docking surfaces, called polo surfaces or just target surfaces.  

Physical Appearance:

Below is a picture of the polo surface I will be using to functionally test my experimental MARCO device.  This target surface is 14x14 cm, with 2x2 cm square targets.  It has been printed on a normal inkjet printer and will probably be glued or taped to a flat surface for testing.

The design is surprisingly simple: you can clearly see the colored targets in each corner of the surface, these are the targets MARCO seeks during the acquisition process.  Coarse acquisition picks out the colors of the targets while fine acquisition seeks the black dots in the target centers.

The small x in the bottom center is the close approach target.  When MARCO has drawn too close to the surface to see the colored targets, it locates this smaller target and commands movement that holds that x in the center of the docking camera's field of view.  The polo surface is designed in such a way that the MARCO vehicle is in perfect position for docking when that x is centered in the field of view of the docking camera.

  It is assumed that MARCO has properly aligned the vehicle with its target when the docking camera is this close, and that no significant perturbations to the docking surface's position or attitude take place in the final moments of docking.  If these assumptions prove incorrect, a miniaturized version of the docking surface, or a different, much smaller target pattern can be printed instead.

Generating a polo surface and file:


This is a screenshot of the Matlab app I wrote to design polo surfaces and generate a polo file.  Currently, there is no software interface between the polo file and a graphic design program to build the actual target surface.  In other words, the user must generate a polo file and then manually draw up the target surface.  It would not be a particularly difficult task to script this process; however, it would be a waste of time at this phase of the project.  I have the polo target surface necessary to test MARCO functionally, and I see no need to build another in the immediate future.


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