| Early Testing |
Two Track Servo Development Begins |
xPC Target
Operational |
xPC Development Part I |
xPC Development Part II |
xPC Development Part III |
xPC and VxWorks Development Part I |
xPC and VxWorks Development Part II |
xPC and VxWorks Development Part III |
xPC and VxWorks Development Part IV |
xPC and VxWorks Development Part
V |
| Using
a DSA, accelerometers, and AT-bus ARCS board to survey resonances on the
elevation structure. Many attempts to get good performance by on-line tuning
of LM628 parameters. |
Ed Bell and Keith Powell
come onboard to work on controller development. Underconstrained elevation
motor mounts investigated. |
Hardware and drivers are
developed for collection of digital encoder outputs and open-loop testing of
elevation begins. First simulation model and controller developed and tested. |
Ed Bell's design track
halted. Powell controller becomes cascaded-PID and first
simulation/closed-loop verification data collected. |
January 2006: xPC
controller design archived for deployment support. Hub bracing wires
installed and incident with bent spider arms occurs. Bandaids attempted on
LM628 servo. Dec 2006: first evidence new notch filters, particularly 20Hz,
are needed surfaces. |
20Hz oscillation confirmed
with xPC controller. New notch filters designed and tested. Newer tuning
parameters also tested. New servo bridge hardware built. Verification of
signal integrity in bridge and DAC hardware. |
xPC development continues
with variable Ki gain in position loop. First attempts at testing the VxWorks
implementation. Luenberger Observer and disturbance decoupling introduced and
tested with xPC Target. |
Work on improving model fit
and servo tuning with xPC begins. Limited amount of sky data with LM628, xPC,
and new VxWorks implementation collected. Various filters in disturbance
decoupling path are tested with xPC Target. |
Dec. 2007: Deployment
testing of VxWorks controller. Open loop testing and data analysis continues
with xPC target for improvement of design simulations for servo optimization. |
System
Identification Toolbox and other tools used for iteration of elevation model.
First (correct) model simulation of 2.8Hz gain peaking. Powell begins work on
gain optimization with improved model. Hardware migrates from xPC to mount
computer and testing continues to discover differences between deployed
VxWorks version and xPC test version. |
65Hz oscillation present on
VxWorks controller, not on xPC version. Cable hang-up on East tape head
incident occurs. Realignment of head and verification of 65Hz mode confirmed
with xPC Target running on mount hardware. Testing in 2005/6 succeeded on both
tape heads with xPC, so East head mode is new. Windup/wobble/runoff issues
with VxWorks controller running latest controller iteration not currently
detected in xPC Target testing. |