itsmyturn

i tried to control the speed of the line-following-robot (at the turnings)using pulse width modulation. but it did'nt work out well. actually, i am planning in such a way that the speed of the robot should decrease continuously from a certain distance b4 the turn ( for eg. it should keep on decreasing speed from 10 cm away from the turn) .can anybody suggest an idea for the speed control and the prediction of the turn ?????

stevez

One thing I'd wonder about - is there any feedback/control in your arrangement or are you just reducing the voltage/power to the DC motor? Sometimes you need some kind of feedback/control because the load can be changing constantly. I don't know what you have now so it's hard to comment further.

An illustration:

If you have a DC fan and want to "control" the speed you might cook up a simple PWM motor speed reducer. As you adjust it you'd see the speed change - and you'd likely be satisfied because once you set the speed it would stay there, more or less.

If you had a model car driven by a DC motor and applied the same simple PWM motor speed reducer things would be fairly steady on a flat uniform surface but as it encountered changes in grade or surface you'd see a corresponding change in speed - because the load on the motor is changing but your simple PWM motor speed reducer can make adjustments for changes in load. If you wanted relatively constant speed you'd add some means of indicating motor speed and a system to adjust the PWM so that the motor speed was constant regardless of load.

I hope this helps you or someone reading. Good luck.

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stevez

stevez

I re-read my post and forgot 't - the simple PWM motor speed reducer can't adjust for changes in load - you would have to adjust your input.

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stevez