Electronics > Mechanical & Automation Engineering

making a plotter with solenoids instead of servos

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Im thinking about putting together an xy plotter from scratch, but I had an idea that if I was using purely magnetic movement over spoolly based or cog based movement the machine could be alot more accurate by a factor of maybe ~100.

However, I heard somewhere that solenoids at about 50cm arent as efficient as smaller ones,  is this true?  and if so why?

Solenoids are fairly nonlinear with regard to force vs distance. Also you would definitely need some kind of position feedback. This is not needed with a stepper motor.

My plans involve using a nychrome wire neatly laid along the dimension to give me resistance over distance,  and my circuits output is a pure binary output, of a more than less than compute - so non-linearities are taken care of.

If the movement of the solenoid is nonlinear then the control loop with the resistive feedback will be very "interesting". To avoid oscillation you'll need to design for the worst case loop dynamics. You might also consider piece-wise linearizing the solenoid behavior. I've never seen this done but if it can be done with fins on the back-end of a missile then I don't see why it couldn't be done with a solenoid. You could also use an FPGA like a MAX 10 and do a system with adaptive loop dynamics. That would be the most awesome of all.

Might be harder than I was thinking,  maybe ill go back to programming,  give hardware a break for the time being.


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