Homing

Overview

Homing is used to mechanically move a motor (connected to a mechanism) to a specific location on the machine, referred to as “home”. Motion tasks then use this home as a reference point for movements that must base a known position on this reference point. Motor movement is usually controlled by a variety of limit switches (end of travel) and a home reference switch. Using these reference points with the logic of the drive allows the machine to find and set the home reference point.

Using Homing

The AKD includes a variety of homing methods (set with HOME.MODE) to accommodate your machine needs:

  • Home using current position (HOME.MODE 0)
  • Find limit input (HOME.MODE 1)
  • Find input limit then find zero angle (HOME.MODE 2)
  • Find input limit then find index (HOME.MODE 3)
  • Find home input (HOME.MODE 4)
  • Find home input then find zero angle (HOME.MODE 5)
  • Find home input then find index (HOME.MODE 6)
  • Find zero angle (HOME.MODE 7)
  • Move until position error exceeded (HOME.MODE 8)
  • Move until position error exceeded, then find zero angle (HOME.MODE 9)
  • Move until position error exceeded, then find index (HOME.MODE 10)
  • Find index signal (HOME.MODE 11)
  • Home to home-switch, including mechanical stop detection (HOME.MODE 12)
  • Home to feedback position (HOME.MODE 13)
  • Home to home-switch for rotary applications (HOME.MODE 14)
  • Find next feedback zero position (HOME.MODE 15)
  • Find home input with dual edges (HOME.MODE 16)
  • Absolute Mode - Calculate and save offset (HOME.MODE 17)
  • Find home input, then find next feedback zero position (HOME.MODE 18)

Each of these homing methods offers a different way to achieve a home reference point based on your particular system mechanics. All homing methods provide the options of adjusting the acceleration, deceleration, and speed for homing moves. In addition, once the homing move is completed, you can either set an offset position or make an offset move as required. Homing modes, guidance for mode selection, and homing examples are included in Selecting and Using Homing Modes.


  • When using any of the methods that use homing switches and limits, please refer to the Input/Output section for proper wiring techniques.

Home Default Window

The Home window provides a means to select your homing method and configure the homing settings. This window also provides a simple controls to start homing and confirm homing success.

Mode Selection:

Use this box to select the appropriate homing mode. Homing modes are described below in Selecting and Using Homing Modes. The active options in the Settings area change depending on the homing mode selected.

Settings:

  • Acceleration: Sets the acceleration ramp used during the homing procedure.
  • Deceleration: Sets the deceleration ramp used during the homing procedure.
  • Direction: Sets the start direction for homing movement.
  • Distance: Sets a prescribed distance you want the motor to move once the home reference point is found. A zero value (default) corresponds to the axis actively returning to the defined position found during the homing process.
  • Position: Sets the current position to a prescribed value once the home reference point is found.
  • Position Lag: Sets the position error threshold, which is used for indicating home reference when using the hardstop modes 8 and 9.
  • Velocity: Sets the initial velocity used for homing moves.
  • Velocity Factor: In modes where a limit is reached, and direction is reversed, the velocity factor allows you to reduce the velocity as a precentage of the homing velocity.
  • Positive/Negative Limit Switch/Home Reference/Peak Current: These fields appear based on the mode selected. For homing to limits and home reference, this field will indicate how the digital inputs are configured as well as provide a link to the digital input page. For Homing to a hard stop, the Peak Current field allows you to set the peak current limit desired during homing.

Controls:

  • Found: When the home reference is found, then this indicator is green.
  • Done: When the home move is complete, this indicator is green.
  • Active: This indicator will be green while the Home move is taking place.
  • Error:This indicator will be red if something in the homing sequence failed.
  • Position Feedback: This window reports the current value for PL.PFB.
  • Auto Homing: Allows the system to auto-home on power up.
  • Start/Stop: Click this button to start or stop the selected homing method.

Selecting and Using Homing Modes

Homing Mode 0: Home Using Current Position

Homing Mode 1: Find Limit Input


Homing Mode 2: Find Input Limit then Find Zero Angle


Homing Mode 3: Find Input Limit then Find Index


Homing Mode 4: Find Home Input

Homing Mode 5: Find Home Input then Find Zero Angle

Homing Mode 6: Find Home Input then Find Index

Homing Mode 7: Find Zero Angle

Homing mode 8: Move Until Position Error Exceeded

Homing Mode 9: Move Until Position Error Exceeded then Find Zero Angle

Homing Mode 10: Move Until Position Error Exceeded then Find Index

Homing Mode 10 Example: Move Until Position Error Exceeded then Find Index.

Homing Mode 11 Example: Find Index Signal.

Homing Mode 12: Homing to a home-switch, including mechanical stop detection

Homing Mode 13: Absolute Mode - Use Feedback Position

Homing Mode 14: Homing to a home-switch for rotary applications

Homing Mode 15: Find next feedback zero position

Homing Mode 16: Find home input with dual edges

Homing Mode 17: Absolute Mode - Calculate and save offset

Homing Mode 18: Find home input, then find next feedback zero position

Using Homing: Advanced

The various homing methods in the AKD offer several options for setting up your home reference.  When using any of the methods that use homing switches and limits, please refer to the Input/Output section for proper wiring techniques.

Related Parameters and Commands

HOME Parameters

PL.FB

CAP0.MODE, CAP1.MODE : Sets index capture method

Digital Inputs and Outputs

DIN Parameters

DOUT Parameters