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Do-More & H2-CTRIO2 Multiple Acceleration Rates

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  • Do-More & H2-CTRIO2 Multiple Acceleration Rates

    I'm looking for a little help figuring out the easiest method to accomplish the following.

    I have stepper motor connected to a ball screw driving a linear axis that is used for positioning and speed control. the whole system is being driven using a Do-More processor and an H2-CTRIO2 card. The linear axis is controlling the withdraw speed and depth of a liquid dipping process, that is why the speed and position is critical.

    an example of what i need to accomplish would be the following.

    Move from home position (0") to final position (10") using the following accel/decel

    1. start at a speed of 2 in/s
    2. Constant acceleration to reach 4 in/s at position 3"
    3. Constant deceleration to reach 2 in/s at position 5"
    4. Constant Acceleration to reach 4 in/s at position 7"
    5. Constant Deceleration to reach 2 in/s at position 10"
    6. stop at position 10"

    My thought right now is to split the move up into multiple (100) velocities (a new velocity every 0.1") and use dynamic velocity to execute the movement.
    this would require a series of math calculations based on speed and position inputs.

    If anyone has any suggestions I would be grateful.


  • #2
    have a look at the CTRUNVEL instruction. Based on your post, you could cascade 5 of these to get the result you want, using the success bit from the first to start the next. If you know the position/inches, use that as the target in the position reached field.


    • #3
      How would I setup the accel/decel between the cycles, its critical that the acceleration and transition through each of the profiles is smooth.
      see the attached position vs speed chart.

      just from the first glance it looks as though I would treat the CTRUNVEL instruction just like the CTAXDYNV except i would have a stop value.
      I would still need to slice the movement into multiple frequencies to accomplish the acceleration.

      thanks for the help ill start playing with it and see what I get
      Attached Files