FilterAssembly < Palomar/PTF

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---++ Filter Labeling

The filter holders should be labeled in accordance with the naming scheme used by the PTF Science Team in order to properly identify the filters. The suggestion is to apply some type of permanent label such as a stamped tin plate riveted to filter holder frame, or a simple engraving directly into the frame. The filters should be identified by *both* ID _and_ NAME as:

|  *ID*  |  *NAME*  |
|  1  |  g  |
|  2  |  R  |
|  3  |  z  |
|  11  |  Haon  |
|  12  |  Haoff  |
|  13  |  OIII  |

[[Main.DavidHale][DH]]

---++ Filter Assembly

*Brief Description:*
The filter changer assembly is a mechanism which provides for motorized selection of one of two filters. One filter will always be in the field. The mechanism provides access for occasional manual exchange of the two filters which can be carried within the assembly. Motion will proceed under commands received by motor controller via TCP socket.

---++++ Items/Tasks remaining until completion:

|  *DONE*  |  *EXPECTED DATE*  |*TASK*  |  *WHO*  |
|  X  |  07/28  |Re-write limit switch algorithm  |  DH  |
|     |  08/01  |Drill & tap hole for motor cable shield drain wire lug  |  KB  |
|  X  |  08/01  |Receive from shop 2nd Base Plate Filter Carriage Assembly  |  KB  |
|  X  |  08/01  |Receive from shop 2nd Filter Frame  |  KB  |
|  X  |  08/01  |Procure fasteners for nut drive assembly|  KB  |
|     |  08/01  |RE-Design and RE-fabricate limit switch arm retainers (or simply purchase). Current ones not adequate.  |  KB  |
|     |  08/01  |Lubricate shafts to reduce shaking/vibration/squeaking (suitable lubricant for proximity to filters?) Roger comments...consider *thin* film of vacuum grease, which has very low volatility and thus will not evaporate.  Interaction with air?  This will look downward and will thus be relatively immune to dust accumulation.  |  KB,RS  |
|  X  |  08/05  |Assemble filter mechanism drive assembly and frame holders (for limit switch software test)  |  KB  |
|  X  |  08/05  |Check new limit switch algorithm in assembled mechanism  |  DH  |
|     |  08/08  |Modify housing for cable clearance  |  KB  |
|     |  08/08  |Receive from shop Cover Door Assembly  |  KB  |
|     |  08/08  |Procure Cover Door Hinge |  KB  |
|     |  08/08  |Add hinged cover on the open side to stop particles/grease falling from mechanism from landing on primary  |  KB  |
|     |  08/15  |Fix limit switch #2 -- sometimes sticks such that it doesn't fully close (this may have been due to faulty limit switch arm retainer)  |  KB  |
|     |  08/15  |Investigate (solve?) stiction (heavy stiction seen in 08/04 test)   |  KB  |
|     |  08/15  |Repair cable braid on D-shell end which connects to filter mechanism  |  DH  |
|     |  08/15  |Final mechanical assembly  |  KB,DH  |
|     |  08/18  |Re-check software after final assembly (may need to be checked after limit switches in their final place)  |  DH  |
|     |  09/05  |Assemble motor controller and power supply into enclosure (need to select a suitable enclosure, probably from campus electronics store)  |  DH  |
|     |  09/05  |Fabricate and fasten name plates or engrave filter labels (see above) into frames  |  KB  |

---++++ Motion Control

   * IMS MicroDrive MForce controller
      * numerous typos in IMS manual
      * when looking at RS422 port, pin 1 is at upper right. See [[%ATTACHURL%/filter_changer_pinout.pdf][my attached drawing]] for pinout description.
      * added 0.01 uF capacitors to IO lines for limit switches, otherwise noise from stepper controller could sometimes trigger limits
   * 51200 steps/rev
   * 1 rot of lead screw = 0.057 inch linear travel (according to KB)
   * Perle IOLAN SDS4 Terminal Server
      * terminal server serial ports are 10 pin RJ-45 but most cables are 8 pin -- use middle 8 pins so subtract 1 from pinout description in Perle manual


---++++ Control Algorithm
*REVISED ALGORITHM 7/28/08* To make up for the lack of hard limits, I've implemented a timeout and distance measuring function. Essentially, the controller will first locate and measure the distance of a filter exchange upon power up (measure in motor steps). It will then move between the soft limit switches and note the distance traveled as a check. If a limit isn't reached within an expected time (about 15 seconds to travel from one end to the other) then the motion will stop. An updated flowchart is attached ([[%ATTACHURL%/Filter_Flowchart_p1r2.pdf][page 1]] and [[%ATTACHURL%/Filter_Flowchart_p2r2.pdf][page2]]). External software will monitor the reported traveled distances in order to monitor troubles.

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
pdf	Filter_Flowchart_p1r2.pdf	r1	manage	101.4 K	2008-08-04 - 18:47	DavidHale	Filter changer flowchart page 1 of 2 (homing) Rev.2
pdf	Filter_Flowchart_p2r2.pdf	r1	manage	68.1 K	2008-08-04 - 18:49	DavidHale	Filter changer flowchart page 2 of 2 (move command) Rev.2
easm	Filter_mechanism_assy_MOSAIC.easm	r1	manage	2002.9 K	2008-07-18 - 05:42	DavidHale	eDwg of filter assembly only
pdf	MFI_Micro_manual.pdf	r1	manage	4376.1 K	2008-07-18 - 05:39	DavidHale	IMS Motion Controller Manual
pdf	P48Mosaic_Filter_Changer_Flowchart_p1.pdf	r1	manage	61.9 K	2008-07-25 - 20:19	DavidHale	Filter changer flowchart page 1 of 2 (homing)
pdf	P48Mosaic_Filter_Changer_Flowchart_p2.pdf	r1	manage	71.7 K	2008-07-25 - 20:23	DavidHale	Filter changer flowchart page 2 of 2 (move command)
pdf	filter_changer_pinout.pdf	r1	manage	14.2 K	2008-07-18 - 05:06	DavidHale	wiring / pinout description for filter changer assembly
mxt	testloop.mxt	r1	manage	0.7 K	2008-07-18 - 05:25	DavidHale	motor controller test program to driver filter back & forth every 3 sec

Topic revision: r13 - 2008-08-18 - DavidHale

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