Dan A Liu, 49Woodland, CA

7366214, Apr 29, 2008

Sep 13, 2005

11/224317

Dan Liu - Newark DE, US
Rongsheng Tian - Newark DE, US
Sean Xiaolu Wang - Centerville DE, US

B & W Property Inc. - Newark DE

H01S 3/00

372 381, 372 3802, 372 3807, 372 69

A diode-pumped solid-state laser (DPSSL) has self-maintained multi-dimensional optimization. The output property of the DPSSL, including optical power, noise level, and the operation conditions of its individual components, including the drive current and temperature of the laser diode, the temperature of the laser crystals and laser cavity, the drive current of the thermoelectric coolers, is monitored and systematically optimized in real time through automatic electronic control using a microprocessor. Such monitoring and optimization enable the DPSSL to maintain its optimum performance in output power, beam quality, noise level, and stability, throughout its lifetime regardless of component aging and change of environmental conditions. A highly accurate temperature monitoring and control method is also developed.

8380370, Feb 19, 2013

Jun 18, 2009

12/487187

Dan Y. Liu - Rancho Palos Verdes CA, US
Richard Y. Chiang - Torrance CA, US

The Boeing Company - Chicago IL

B64G 1/24

701 13, 701 3, 701 4, 701 11, 701400, 701408, 701501, 701505, 701512, 701513, 701523, 701534, 2441581, 2441584, 2441588, 244164, 244165, 244171, 2441711, 2441726

A system and a method for commanding a spacecraft to perform a three-axis maneuver purely based on “position” (i. e. , attitude) measurements. Using an “inertial gimbal concept”, a set of formulae are derived that can map a set of “inertial” motion to the spacecraft body frame based on position information so that the spacecraft can perform/follow according to the desired inertial position maneuvers commands. Also, the system and method disclosed herein employ an intrusion steering law to protect the spacecraft from acquisition failure when a long sensor intrusion occurs.

8620496, Dec 31, 2013

Jul 23, 2008

12/178440

Dan Y. Liu - Rancho Palos Verdes CA, US
Qinghong W. Wang - Torrance CA, US
Richard Y. Chiang - Torrance CA, US

The Boeing Company - Chicago IL

B64G 1/38
B64G 1/28

701 13, 244165, 244170

A system for damping nutation and removing wobble of a spacecraft spinning about a given axis is provided. The system includes a sensor configured to determine three dimensional attitude measurements of the spacecraft, a processor operatively coupled to the sensor and configured to execute a process that facilitates aligning the spin axis with a spacecraft momentum vector. The processor, when executing the process, is programmed to receive spacecraft attitude data from the sensor, determine a torque command using the received attitude data, and control a momentum storage actuator on the spacecraft using the determined torque command such that an angular deviation about the given axis is reduced.

5310143, May 10, 1994

Jun 10, 1993

8/075843

John F. Yocum - Rancho Palos Verdes CA
Dan Y. Liu - Rancho Palos Verdes CA
Richard A. Fowell - Culver City CA
Douglas J. Bender - Redondo Beach CA

Hughes Aircraft Company - Los Angeles CA

B64G 124

244164

The three axes thruster modulation (8) of the present invention accepts three axes of input torque commands or angular acceleration commands and generates thruster selection and thruster timing (40) information which is used to fire thrusters (48) for the purpose of spacecraft attitude control and velocity change maneuvers. The modulation logic (8) works in all three axes simultaneously and is suitable for use with an arbitrary thruster configuration, including a configuration in which individual thrusters or thruster groups do not produce torques about mutually orthogonal axes. After thruster selection and on-times have been determined, the modulation logic (8) uses this information to compute a best estimate of the actual rate change (42) which is then compared to the commanded rate change (44) to develop a residual unfired rate change. The residual unfired rate change is retained and fed forward for addition to the subsequent acceleration command in computing the commanded rate change for the subsequent sample period (10, 20, 30). As a result, all commanded rate changes will ultimately be fired even if the commanded rate change is below a minimum rate change achievable.

5311435, May 10, 1994

Nov 27, 1991

7/800660

John F. Yocum - Rancho Palos Verdes CA
Dan Y. Liu - Rancho Palos Verdes CA

Hughes Aircraft Company - Los Angeles CA

G01C 2100
G06G 778

364459

A method of attitude control for spacecraft with flexible structures utilizes an estimator/state controller pair with on-board time-varying gain scheduling. The control method includes an attitude estimator (100) for each axis, which uses rate input from inertial reference sensors (4, 5, 6) to produce estimates (37, 38, 39) of each of the state variables. The estimator employs a predictor-corrector structure which computes initial rate and position estimates for each sample interval and corrects these values by weighing them with iteratively-calculated time-varying gains according to equations 35 and 36. The state controller (40) for each axis operates on these inputs, combining them with position and rate commands (41, 42) and weighing the results with time-varying gains calculated iteratively for each sample period according to equations 46, 47, and 48. The final result is a commanded control acceleration (50) which is forwarded to a thruster modulation logic.