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optics

flexCombinedMotion

This support was designed for APS flexure stages, but it should work for other coarse/fine motor applications.

APS Flexure Hardware

An APS flexure stage includes the following hardware:

  • A New Focus picomotor controller
  • A New Focus open-loop picomotor (providing coarse motion and a large travel range)
  • A PI piezo controller
  • A PI piezo (providing fine motion and a small travel range)
  • A Lion Precision cap sensor driver
  • A Lion Precision cap sensor (providing absolute positioning)
  • A measComp USB-2408-2AO or LabJack T8 (analog inputs to read the cap sensor)

Motivation

The existing CoarseFineMotor.db could not be used because it was not guaranteed that the open-loop picomotor would get within the piezo’s range of the desired position. flexCombinedMotion.st was adapted from a hybrid motion program already in use at an APS beamline.

Modes of operation

  • Fast: combined motion using the specified piezo range as the deadband
  • Precise: combined motion using the specified deadband as the deadband
  • Coarse: motion using only the coarse motor
  • Fine: motion using only the fine motor

Example configuration

Motors

  • PREFIX: optics:
  • Picomotor: $(PREFIX):nf:c0:m1
  • Piezo: $(PREFIX):pi:c0:m1
  • Piezo range: 15um
  • Analog input reading cap sensor voltage: $(PREFIX):LJT8:1:Ai0
  • Cap sensor conversion factor (um/V): 32.59
  • Desired cap sensor name: cap1
  • Desired combo motor name: m1

IOC config

The flexCombinedMotion.iocsh file describes the required and optional macros it accepts. This example includes only the required macros:

iocshLoad("$(OPTICS)/iocsh/flexCombinedMotion.iocsh","P=$(PREFIX),C=cap1,V=$(PREFIX)LJT8:1:Ai1,UMV=32.59,M=m1,LLM=0.0,HOME=7.5,HLM=15.0,FM=pi:c0:m1,CM=nf:c0:m1")

Notes: The LLM/HLM values can be used to restrict the usable range of the piezo. The HOME can be near LLM or HLM to allow more fine steps in one direction before a coarse move is needed.

MEDM/caQtDM screen macros

flexCombinedMotionTop.{adl,ui} 

"P=optics:,M=m1,CM=nf:c0:m1,FM=pi:c0:m1,C=cap1"

flexCombinedMotion.{adl,ui} 

"P=optics:,M=m1"

flexCapSensor.{adl,ui} 

"P=optics:,C=cap1"