Input Card Setup

Analog Input Card Setup:

The 5069-IY4 and the 1756/1769-IF4FXOF2F allow 2 points to be entered on the Analog input setup, and it interpolates the analog input properly based on those 2 points (example screen below); and after entering the data points, change the units from volts to inches:

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Step 16

Setting up the AOI and Its Inputs and Outputs:

>SHA_PostionControl. This motion block provides the closed-loop SHA control. Position mode, and Position with Force Limit (when the EnableForceMaxLimit and/or EnableForceMinLimit are True) modes are supported.

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Inputs:

  • Backing AOI Tag Instance
  • PositionReference (REAL, Position Units)
    • Recommend the use of a VIRTUAL AXIS and simply use <AXIS>.CommandPosition for this input.
    • This allows for the motion planner to generate MAM, MAJ, MAG, CAM, etc.
    • Alternative is to simply provide a value, but kinematic profiles are typically required.
  • PositionFeedback (REAL, Position Units)
    • Scaled feedback from high-speed analog input, etc.
    • For analog input, set the notch filter to the highest value for fastest updates.
    • If scaling/offset needs to be done in ladder, then run that logic in this same task, and run it before the SHA_PositionControl is run.
    • Coordinate the positional resolution with the PositionDeadband value (0.001 typical).
  • FeedforwardVel (REAL, Position Units/Second)
    • Recommend the use of a VIRTUAL AXIS and simply use its CommandVelocity for this input.
  • Force Limits
    • Max (REAL, lbs)
    • Min (REAL, lbs)
    • Same recommendation: use a virtual axis for needed profiles if the Force limit needs to be changed/ranged in a controlled manner, otherwise a rate-limited or a fixed value variable can be used for simpler applications.
    • Force Limit control coordinates with the ForceLimitingDeadband value (typically 10 to 25).
    • Force Limit control also respects the SHA_Config.TorqueMax (for extend force) and SHA_Config.TorqueMin (for retract force). If these Torque Min/Max settings are set too low, they can prevent the specified ForceMax/ForceMin from being reached. Conversely, setting the TorqueMin or Max values just slightly higher than what is needed to reach the desired Force value helps minimize Force overshoot when entering the Force limit control zone.
  • Extend/Retract Pressure Feedbacks
    • Provide Feedback (REAL, PSI)
    • In this demo, IF4x analog inputs channels 0,1, and 2 were aliased to extend pressure, retract pressure, analog linear feedback (Position).
    • Use of Volts to Engineering Units is accomplished in the IF4X channel config.
    • If analog feedback is used, set the notch filter to the highest value for fastest updates; disable unused channels. If ladder scaling/offset is used, it must also run in the MotionTask and must be run prior to running the SHA_PositionControl block.
    • Load cell force feedback supported using Extend Pressure input in desired force units and SHA_Config tag ExendForceGain set to 1.0
    • Extend / Retract can be optionally set to 0 when not available.
  • Config
    • SHA_CONFIG Data tag, public user defined data type.
    • The SHA_Config data values are provided by Kyntronics for out of box tuning, based on the SHA size, the configuration and application.
    • Use the Position and Force SHA_RelayId blocks, as needed, to help tune your system if the RPI is slower than 1 millisecond or if the position and pressure feedback are slower than 1 millisecond. See Section 10 for more information on the SHA_RelayId blocks.
  • DriveCommand
    • The CIP AXIS Tag associated with the actuator
    • AOI uses diagnostic and feedback data available in tags each AOI scan.
    • User explicitly sets velocity command in ladder (See Motion Group Task)
  • EnableForceMaxLimit, BOOL
    • Set True to enable the extend ForceMax value to be respected and applied.
  • EnableForceMinLimit, BOOL
    • Set True to enable the retract ForceMin value to be respected and applied.
  • EnableFeedforward, BOOL
    • Set True to enable the position velocity feedforward values to be respected and applied, which is useful when high speed positional moves are desired. Set False to disable, which can be useful when moving slowly into a Force Limit zone, to lessen any “bounce back” when the Force limit zone is small and/or the Force will rise very rapidly.

Explanation of AOI outputs:

  • Status (DINT bit flags)
    • Error Codes
    • 0 for no error
  •  Force (REAL, lbs)
    • Current effective actuator force
    • Positive is extending push, negative is pulling retract.
  • Command Pump Speed (REAL, Hz)
    • CIP AXIS is setup for 1 position unit per rev, so pump speed has units of Hz.
    • User can choose to use the AOI controller value or not.
    • Controller block will track current CIP axis speed and torque such that the user can choose when to close the loop.
    • Positive Speed extends, negative speed retracts.