From colu@mbari.org Wed Feb 9 16:32 PST 1994 Received: from hp850.mbari.org by otter.mbari.org with SMTP (1.36.108.4/15.6) id AA01137; Wed, 9 Feb 1994 16:32:04 -0800 Return-Path: Received: by hp850.mbari.org (15.11/15.6) id AA24403; Wed, 9 Feb 94 16:27:57 pst Received: by hp850.mbari.org (15.11/15.6) id AA24400; Wed, 9 Feb 94 16:27:51 pst From: Luke Coletti Subject: Pan and Tilt. To: chma@hp850.mbari.org (Mark Chaffey), colu@hp850.mbari.org (Luke Coletti), kiwi@hp850.mbari.org (William Kirkwood), matthews@hp850.mbari.org (Micheal Matthews), meed@hp850.mbari.org (Ed Mellinger), neji@hp850.mbari.org (Jim Newman), pean@hp850.mbari.org (Andrew Pearce) Date: Wed, 9 Feb 94 16:27:50 PST Mailer: Elm [revision: 66.25] Status: RO Hello all, I'll formalize what was discussed today regarding Pan and Tilts. 1. Measurements were recently taken and the results were presented that showed backlash from the poteniometer feedback to be as high as 1.4 deg in resolved output shaft position or 3.125 * that in actual pot backlash. Data and reduction was distributed. 2. A method for the control of the Pan and Tilt was represented where by the feedback pot is used as a absolute indicator of differential positon of the Pan and Tilt relative to its calibrated vehicle & camera attitude. The pot is used to confirm position within the accuracy deadband now defined at .25 degrees. An optical "system" zeroing point was suggested too. 3. Coupled noise has shown to be a major problem, a measurement will be taken with the current hardware to see how well position can be resolved. Various methods will be tried to reduce the effects of the coupled noise. The DC\DC converter is a noise problem too. Andy will begin coding A/D routines first. 4. ROS will have ready within a week a modified poteniometer mount for the PT-10. It has been designed to accomodate a 7/8" servo body. The gear ratio will be .94:1 using anti-backlash gears. I have ordered a single turn pot that I will have ROS incorporate and will retest the unit at the first opp- ortunity. The new pot mount will be available from ROS on all high-speed PT-10's. Data will be distributed. 5. Concern was expressed about the limit collars being retained by a set- screw, a pin was thought best. Will advise ROS and seek response. 6. A performance test will be done to test the PT-10's capability at driving Tiburon's expected camera mass. The test will probably for starters be done out of water and will need an appropriate mockup. 7. The first method of user control will be a rate control, rate and direction will be controlled using the two upper left console joysticks. A slaved rate control could be done too. My Thanks. Luke