Abstract: A method is provided for guiding an in-flight vehicle having course divert apability toward an intercept with a target. Using a sensing device mounted on the vehicle, target data is acquired to establish a relative position vector between the vehicle and the target. A trajectory course for the vehicle is selected such that it is offset from a collision course with the target. The offset is defined within in a target impact plane perpendicular to the relative position vector. The total thrust of the vehicle associated with its course divert capability is directionally controlled through first and second orthogonal components. To reduce offset the second component is directed to cause the trajectory of the vehicle to spiral around the relative position vector.

Abstract: A method of guiding an in-flight vehicle toward a target exhibiting a known or predictable thrusting profile is provided. The vehicle undergoes an alternating series of vehicle coasts and diverts during the vehicle's terminal intercept phase of flight. Position and velocity information of the target with respect to the vehicle is used to select a course change during each vehicle coast. The course change is intentionally offset from a collision course with the target and is effected by the next divert in the series. The amount of offset is such that the final coast results in a target intercept.

Abstract: A method of using two diverts in combination to guide an in-flight vehicle rom its initial flight path at target acquisition to a desired flight path prior to target interception is provided. The two diverts are of known and different magnitudes. The magnitude of an initial projected miss at a closest approach to the target is used to determine the order and timing of the two diverts. At the completion of the second divert, the vehicle is on the desired flight path which may be either a collision or offset course trajectory as required by the vehicle's terminal guidance law.

Abstract: A method of Kalman filtering for estimating the position and velocity of a racked object is provided. A Kalman filter is initialized with at least position and velocity error states in an inertial computational frame. Sensor measurements are used to develop a measured line-of-sight vector to the object. Matrix transformations are used to analytically rotate the sensor measurements into a measurement frame. The measurement frame is defined as having one axis pointing towards the estimated relative position of the object. The use of the measurement frame allows the method to be adaptable to any line-of-sight/computational frame geometry. Since statistical correlation of the measurements is not present in the measurement frame, the number of computations at each filter update is reduced.

Abstract: An optical assembly 7, 8 providing an optical relay of a borescope 1 has a plurality of lenses 7 spaced apart by tubular spacers 8 through which the optical path extends. The spacers 8 include formations 9, 10 and 11 for connecting adjacent spacers and for housing the lenses 7 such that the spacers 8 and the lenses form a self supporting assembly. The optical assembly 7, 8 locates in a window tube 19 located within a tubular shaft 2 with a fibre optic bundle 16 occupying a duct 17 formed between the window tube and the shaft. The borescope 1 is convenient to assemble with minimum contamination and maximizes the optical path cross sectional area available.