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Dead band or 'PACE' 18F2431 motor movement and stop regulation

Discussion in 'Oshonsoft' started by camerart, Dec 13, 2015.

  1. camerart

    camerart Active Member

    Joined:
    Jun 12, 2008
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    Location:
    Dorset UK.
    Hi,

    I'm using 18F2431 PICS for controlling a servo motor movement.
    The existing program has a 'dead band', for slowing down the motor as it arrives at a set point.
    The motor is controlled by PWM.

    The problem is: If I set a certain 'dead band' width so that the motor stops at the set point, it either over-runs or under-runs depending on the PWM. When the motor needs to move a long way, I want a high PWM and low PWM for short movements. It's proving difficult to set the PWM for each circumstance.

    I've come up with an idea! I know the maximum speed that the motor can run, so if I program a 'PACE' movement, in a similar way to a pace runner in a race. The PACE moves at just below the max motor speed the motor can run. The motor is programmed to follow the PACE. If it get close it slows down, if it's a long way behind it moves fast to catch up. when the PACE gets to the set point, it stops, the motor gets nearer to the PACE and slows down and stops. In a similar way to dead band, but should suit all occasions.

    Does this sound sensible?

    Camerart.
     

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