Estimating Thruster Impulses From IMU and Doppler Data

A computer program implements a thrust impulse measurement (TIM) filter, which processes data on changes in velocity and attitude of a spacecraft to estimate the small impulsive forces and torques exerted by the thrusters of the spacecraft reaction control system (RCS). The velocity-change data are obtained from line-of-sight-velocity data from Doppler measurements made from the Earth. The attitude-change data are the telemetered from an inertial measurement unit (IMU) aboard the spacecraft.

The TIM filter estimates the three-axis thrust vector for each RCS thruster, thereby enabling reduction of cumulative navigation error attributable to inaccurate prediction of thrust vectors. The filter has been augmented with a simple mathematical model to compensate for large temperature fluctuations in the spacecraft thruster catalyst bed in order to estimate thrust more accurately at dead-banding “cold-firing” levels. Also, rigorous consider-covariance estimation is applied in the TIM to account for the expected uncertainty in the moment of inertia and the location of the center of gravity of the spacecraft. The TIM filter was built with, and depends upon, a sigma-point consider-filter algorithm implemented in a Python-language computer program.

This program was written by Michael E. Lisano and Gerhard L. Kruizinga of Caltech for NASA’s Jet Propulsion Laboratory.

This software is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-45825.

White Papers

The Changing Face of Robotics
Sponsored by maplesoft
Improving Medical Devices with Force Sensing Technology
Sponsored by tekscan
Electropolishing for the Aerospace Industry
Sponsored by able electropolishing
Reverse Engineering
Sponsored by Servometer
RR1P Rugged ATR Pluggable Canister RAID Data Storage Delivers Continuous Data Recording for ISR
Sponsored by winchester systems
Windows CE Development for RISC Computers Made Easy
Sponsored by Sealevel

White Papers Sponsored By: