Transcript Binh report

Binh research 08 Dec 2009
• Working on ST and non-convex time stepper
within Bullet
• DONE with initial solver for frictionless ST.
• Working on non-convex time stepper
(required changes in collision detection)
Solver for frictionless ST
• Right now use OOQP+MA57 to solve a simple
QP from frictionless ST
• Future:
– OOQP+Cholmod (should be faster and more
robust than MA57)
– OOQP+UMFPACK(work with indefinite
system)+LUMOD(sparse update)
Solver for frictionless ST
• Once done, need to gather data on how much
KKT system change during 1 step. If small
enough then can use sparse update (LUMOD)
• If sparse update not efficient then may have
to work on way to warm-start OOQP (warm
start Interior Point Method is tricky)
• Simple optimization = group column in same
contact and pivot them at the same time
should help A LOT (need to try)
ST with linearized friction
• Should be similar to frictionless case
• Structure is different so may need a slightly
different optimization
ST with quadratic friction
• Not spend much time on this subject yet
• OOQP implements Mehrota-Gondzio
predictor corrector Interior Point Method and
we should be able to extend it to solve SQP
problem (I had some papers on it but havent
read them yet)
This week
• Get frictionless OOQP solver done and get
some statistical data on a big physics scene.
• Work on OOQP-Cholmod as it should be 3-5x
faster (benchmark on convex QP showed that
)