David S Uetrecht2209 Thorley Pl, Palos Verdes Estates, CA 90274

6681159, Jan 20, 2004

Oct 28, 2001

10/039488

Rongsheng Li - Hacienda Heights CA
Jeffrey A. Kurland - Marina Del Rey CA
Alec M. Dawson - Manchester CT
David S. Uetrecht - Palos Verdes Estates CA

The Boeing Company - Seattle WA

B64L 100

701 13, 701226, 701 8, 701 4, 244164, 244165, 244171

Methods and structures are provided that enhance attitude control during gyroscope substitutions by insuring that a spacecrafts attitude control system does not drive its absolute-attitude sensors out of their capture ranges. In a method embodiment, an operational process-noise covariance Q of a Kalman filter is temporarily replaced with a substantially greater interim process-noise covariance Q. This replacement increases the weight given to the most recent attitude measurements and hastens the reduction of attitude errors and gyroscope bias errors. The error effect of the substituted gyroscopes is reduced and the absolute-attitude sensors are not driven out of their capture range. In another method embodiment, this replacement is preceded by the temporary replacement of an operational measurement-noise variance R with a substantially larger interim measurement-noise variance R to reduce transients during the gyroscope substitutions.

8265804, Sep 11, 2012

May 29, 2009

12/475072

David S. Uetrecht - Palos Verdes Estates CA, US
David D. Needelman - Torrance CA, US
Tung-Ching Tsao - Cupertino CA, US

The Boeing Company - Chicago IL

B64G 1/36

701 13, 701531

A method for controlling a vehicle may include sensing a position of each of a plurality of stars relative to the vehicle. The method may also include determining an attitude of the vehicle using the sensed positions of the plurality of stars, and the attitude may be determined either with or without using information from a gyro or sensor for measuring angular velocity. The method may additionally include implementing a set of strategies to optimize determination of the attitude of the vehicle when using only the sensed positions of the plurality of stars, without information from the sensor for measuring angular velocity. The method may further include controlling the vehicle based on the determined attitude of the vehicle.

8439312, May 14, 2013

Jun 18, 2008

12/141832

Yiu-Hung M. Ho - Palos Verdes Estates CA, US
Jeffrey A. Kurland - Rancho Palos Verdes CA, US
David S. Uetrecht - Palos Verdes Estates CA, US

The Boeing Company - Chicago IL

B64G 1/26
B64G 1/10

244169, 2441588

The present system and methods enable simultaneous momentum dumping and orbit control of a spacecraft, such as a geostationary satellite. Control equations according to the present system and methods generate accurate station-keeping commands quickly and efficiently, reducing the number of maneuvers needed to maintain station and allowing station-keeping maneuvers to be performed with a single burn. Additional benefits include increased efficiency in propellant usage, and extension of the satellite's lifespan. The present system and methods also enable tighter orbit control, reduction in transients and number of station-keeping thrusters aboard the satellite. The present methods also eliminate the need for the thrusters to point through the center of mass of the satellite, which in turn reduces the need for dedicated station-keeping thrusters. The present methods also facilitate completely autonomous orbit control and angular momentum control using.

5098041, Mar 24, 1992

Jun 7, 1990

7/534216

David S. Uetrecht - Redondo Beach CA

Hughes Aircraft Company - Los Angeles CA

B64C 120

244164

An attitude and nutation control system (30) for a momentum-biased vehicle (10) having roll, pitch, and yaw axes which employs a normal mode estimator (32) which predicts steady-state values for roll attitude, roll rate, and yaw rate. The normal mode estimator (32) receives instantaneous roll attitude information from an earth sensor (34) and optionally receives roll and/or yaw rate information from roll gyro (35a) and yaw gyro (35b). A logic circuit (36) coupled to the normal mode estimator (32) generates correction signals when the steady-state values for roll attitude, roll rate, and yaw rate are outside predetermined limits. A plurality of thrusters (14a-d) produce torque for bringing the steady-state values for roll attitude, roll rate, and yaw rate within predetermined limits. A sample/hold-off control circuit (68) samples correction signals between thruster activations while a optimal thruster selection logic (70) employs a linear program to compute torques associated with changes in the correction signals for use by the normal mode estimator (32), as well as activating selected thrusters (14 a-d).