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  • Author Author: dubbie
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HoloPiBot # 1 : My Unofficial Entry

dubbie

As I didn't want to be an official entry to this PiCasso challenge I have waited until the official contestants have been announced (well done to all of them) in order to avoid muddying the waters, so to speak. At the moment I'm still not sure what all of them will be doing so if any of my ideas clash just let me know and I'll do something else.

 

As I really like mobile robots (I really really like mobile robots) I wondered how to incorporate a mobile robot into this challenge. My idea is to make a holonomic mobile robot with a downward looking camera that is programmed to randomly move in the horizontal plane but maintaining its orientation. This would be placed over an art work, perhaps even a Picasso as I quite like some of his work, with a magnified image of the small portion of the picture captured by the camera being displayed on a flat screen video display carried on the top of the holonomic robot.

 

I have already been learning Pi (with my very old Pi B connected via Ethernet) and I have purchased some step motors and drivers in order to start creating the holonomic driving characteristic. I do have access to a proper PC display which has an HDMI input and also a 12V power input (I also have two lead acid batteries salvaged from a building fire alarm) but it might be a bit heavy for the motors. I had originally though of using a 5 inch or 7 inch display but that would mean purchasing one - which I might still do anyway. Then I hope to 3D print most of the structure holding everything together to make everything as smooth and pretty as possible. I might even spray paint some of it.

 

I'll have to see how it goes. I have to go now as I have three more shelves to put up.

 

Dubbie

  • in reply to jc2048

    Jon,

     

    I hadn't thought of that, but then where would all the fun be?

     

    Dubbie

  • in reply to dubbie

    ...and also synchronising all the powered directional motors so that they all point in the same direction.

     

    chain and sprocket them together and just have one motor to set the direction would be one way to do it

  • in reply to shabaz

    Shabaz,

     

    The omniwheels are one of several ways of achieving holonomic movement. I saw a new one only yesterday that relied of wheels slip from four powered wheels, one of each side of the square robot. I'm going to have to have a go at that some time. The approach I aim to use is to use four powered points, one of each corner. Each powered point has two motors, one selecting direction and the other providing the wheel rotational movement. I like this method as it does not rely on wheel slip, which most other methods do to some extent at least. The difficulties are in getting the weight through the axles of the wheels otherwise you get a sort of sagging effect, and also synchronising all the powered directional motors so that they all point in the same direction. I am planning to use step motors for the steering but I can use servo motors if needed.

     

    Dubbie

  • Hi Dubbie,

     

    This sounds interesting : )

    I initially didn't know what holonomic was, so I had to google it : )  I saw a robot using omniwheels at a trade show, it's astonishing seeing the movements they can do. Good luck with the design challenge!

  • in reply to three-phase

    Donald,

     

    I know, but even though I'm retired I still have responsibilities. I managed two shelves today then ran out of time and wood. I'll get the last one done next week hopefully, then back to the robots.

     

    Dubbie