Abstract

This talk will show that attitude Kalman filters can be simple in design while also being robust and accurate despite the highly nonlinear nature of attitude (i. e., orientation) estimation. Three different filters are discussed, all using quaternions and small-angle approximations of attitude errors: an Extended Kalman filter as well as an Unscented Kalman filter for a gyro-based situation, and an Extended Kalman filter for a gyro-less one. In additon to the three-axis attitude, all of the filters also estimate corrections to the angular velocity – random walk modeled biases in the gyro measured case, and first-order Markov modeled corrections in the gyro-less case, which involves angular velocity computed from mass properties and control data.
The filters are evaluated using extensive real and simulated data from low-Earth orbiting NASA satellites such as Tropical Rainfall Measurement Mission, Solar, Anomalous, and Magnetospheric Particle Explorer, Earth Radiation Budget Satellite, Wide Field Infrared Explorer, and Fast Auroral Snapshot Explorer. The evaluations predominantly involve stressing “magnetometer-only” scenarios, i. e., using only a three-axis magnetometer to sense the attitude. Comparisons are made with attitude and rate knowledge obtained using coarse sensors and single-frame algorithms, and also with results from an Unscented Kalman filter with a more complicated attitude pameterization.

Bio

Dr. Murty Challa received a B.Sc. in physics from Andhra University, Visakhapatnam, India, and a Ph.D. in physics from the University of Georgia, Athens, Georgia. His professional interests and actvities include: estimation and data fusion algorithms such as Kalman filters, batch estimators, and simultaneous localization and mapping; track correlation/ association; guidance, navigation, and control for spacecraft and unmanned vehicles; missile defense; quantum computing; statistical mechanics; computational physics; solid state physics/ materials science. He is currently a member of the Senior Professional Staff of Johns Hopkins Applied Physics Laboratory (JHU/APL), Maryland, USA. Prior to JHU/APL, he was senior staff at Institute for Defense Analyses, Alexandria, VA, and at Computer Sciences Corporation supporting NASA Goddard Space Flight Center, Greenbelt, MD. Dr. Challa’s academic positions include post-doctoral appointments in physics at Michigan State University and Virginia Commonwealth University, and an adjunct position in physics at George Washington University. He has also served as a consultant to Iridium Satellite, LLC.

We are super excited for you to join us on our first LCSR social event of this spring term! We are planning to get together for an ice-skating session on Thursday January 26^th @6:00 pm at the JHU ice rink, followed by an informal happy hour at the Charles Village Pub (we are not providing food or drinks this time). The ice rink on the night of the 26^th is dedicated to JHU grad students, so it’s a good opportunity to mingle with peeps from other departments as well! If you are interested in joining us, please sign up on this google form – we will be taking in people on a first come first serve basis.

We currently have 27 available tickets open only to LCSR students. However, you are free to bring in extra guests by signing them up yourselves at this link (please read through JHU’s policy on bringing in non JHU affiliated guests on their website). We will be meeting up at Hackerman breezeway at 5:40pm to head together as a group because all tickets are registered under 3 of our committee members’ names. The skating session will last for 1.5 hours.

FAQs:

1. Do I need to know how to skate? Nope. You are all welcome to join, no matter much or little you know about ice-skating!
2. Do I need to bring in anything? No. Come as you are! JHU will provide skates, that’s all you’re going to need. Just wear thicker socks for added comfort/padding. But you’re welcome to bring in your own skates or protective equipment (knee/butt pads) if you wish.

Lastly, we wanted to emphasize that the aforementioned date is TENTATIVE and weather dependent. Should the clouds bless us with rain on that Thursday, we will need to postpone the event. We will send an email on Monday January 23^rd to confirm the final date, but it will most likely be a Thursday or Friday either the week of January 23 or 30.

Looking forward to cruising with you soon ⛸️⛸️!

Bagels!