Abstract: A ballistic descent vehicle comprises an airframe, one or more control surfaces for controlling a descent of the vehicle, a controller, and a sensor suite to estimate both relative position, velocity, and flight path angle. Such a controller guides the vehicle, via the control surfaces, based on the estimated vehicle states, and a preprogrammed equivalent airspeed versus flight path angle two dimensional surface. During flight, the controller periodically consults the pre-computed equivalent airspeed versus flight path angle surface to obtain a desired flight path angle such that the vehicle asymptotically approaches a desired terminal approach angle while successfully navigating to the target. The use of this preprogrammed surface allows for the control of such vehicles with significantly lower computational resources, smaller control surfaces, and/or without relative airflow sensors onboard.

Abstract: A new approach for rapid slew and settle of small satellites is based on four single degree-of-freedom control moment gyroscopes with variable speed flywheels (or reaction wheels) in a pyramid configuration, combined with path and endpoint constraint time-optimal control. The path and endpoint constrained time-optimal control can be augmented with momentum management without the use of additional actuators.

Abstract: A new approach for rapid slew and settle of small satellites is based on four single degree-of-freedom control moment gyroscopes with variable speed flywheels (or reaction wheels) in a pyramid configuration, combined with path and endpoint constraint time-optimal control. The path and endpoint constrained time-optimal control can be augmented with momentum management without the use of additional actuators.

Abstract: A disk drive includes a rotatable disk, a transducer, an actuator, and a controller. The disk includes a first servo burst pattern in a first radial spoke of the disk, and a second servo burst pattern in a second radial spoke of the disk. The first and second servo burst patterns are radially offset from each other and are associated with a plurality of data tracks extending through the first and second radial spokes. The transducer is configured to read the first and second servo burst patterns on the disk to generate a servo burst signal. The actuator is configured to position the transducer relative to the disk. The controller is configured to control positioning of the transducer relative to the tracks on the disk based on the servo burst signal.