Abstract: A system and method are disclosed for tracking a position of an orbital body relative to a planetary body. A processor (602) with memory (603) stores reference data associated with the planetary body. A single sensor (601) coupled to the processor, generates a scene frame (212) of a portion of the planetary body. A reference frame corresponding to the scene frame is retrieve from the memory. An image or one or more features of the scene frame is compared with a corresponding image or features associated with the reference frame. An attitude and/or an ephemeris of the orbital body is estimated by solving an equation set in open form or closed form based on the comparison and inputs such as rotation rate value and a linear velocity value associated with the orbital body.

Abstract: An apparatus in one example has: an electrostatic device having an engagement portion; and an attractive electrostatic force selectively applicable by the electrostatic device to the engagement portion for at least one of holding the electrostatic device or providing locomotion to the electrostatic device.

Abstract: A gimbal drive module comprising an elbow (24) formed of composite material and having two legs. On one leg, elbow (24) includes an azimuth drive module (26). On the other leg, elbow (24) includes an elevation drive module (30). Azimuth drive module (26) and elevation drive module (30) include motors which when energized enable displacement of the respective legs in order to control the azimuth and elevation of elbow (24) to enable pointing of a structure, such as an antenna (18), as may be located on a second elbow outboard end (20).

Abstract: A high precision pointing mechanism (10), particularly for use in space applications. The precision mechanism includes a motor assembly (26) connected to a displaceable elbow (24). A controller (166) determines a motor torque command (170) in accordance with a position error (168). The position error is used to generate proportional gain (172), derivative gain (182), and integral gain (194) compensation terms. The sum of the proportional compensation component (172) and derivative compensation component (182) is used to generate a proportional-derivative compensation component. The proportional-derivative compensation component is input to a hyperbolic tangent function (188), which substantially models the friction characteristic of the high precision pointing mechanism (10). The output from the hyperbolic tangent function (188) is used in combination with the proportional-derivative compensation component and the integral compensation component to generate the motor torque command (170).

Abstract: A method that allows a space vehicle to determine navigation information represented by the contents of a state vector. The method includes the steps of intermittently receiving navigation signals, initializing the state vector with an estimate of the navigation information, and generating a predicted state vector that represents the predicted values for the navigation information after a predetermined time increment in the future. The method further determines whether a navigation signal has been received within a predetermined window of time from a navigation beacon. If a navigation signal has been received, the method updates the state vector and the contents of the state vector are propagated forward in time to provide an estimate of the navigation information after a predetermined time increment. In some instances, however, a navigation signal is not received within the predetermined window of time.