Techniques are provided for determination of a guided-munition orientation during flight based on lateral acceleration, velocity, and turn rate of the guided-munition. A methodology implementing the techniques, according to an embodiment, includes obtaining a lateral acceleration vector measurement and a velocity of the guided-munition, and calculating a ratio of the two, to generate an estimated lateral turn vector of the guided-munition. The method also includes integrating the estimated lateral turn vector, over a period of time associated with flight of the guided-munition, to generate a first type of predicted attitude change. The method further includes obtaining and integrating a lateral turn rate vector measurement of the guided-munition, over the period of time associated with flight of the guided-munition, to generate a second type of predicted attitude change. The method further includes calculating a gravity direction vector based on a difference between the first and second types of predicted attitude change.

Model based inertial navigation for a spinning projectile is provided. In one embodiment, a navigation system comprises: a strapdown navigation processor; a propagator-estimator filter, the processor inputs inertial sensor data and navigation corrections from the filter to generate a navigation solution comprising projectile velocity and attitude estimates; an upfinding navigation aid that generates an angular attitude measurement indicative of a roll angle; and a physics model performing calculations utilizing dynamics equations for a rigid body, the model inputs 1) projectile state estimates from the navigation solution and 2) platform inputs indicative of forces acting on a projectile platform, and outputs a set of three orthogonal predicted translational acceleration measurements based on the inputs; the filter comprises a measurement equation associated with the physics model and the upfinding navigation aid and calculates the navigation corrections as a function of the navigation solution, the predicted translational acceleration measurements, and attitude measurement.

Model based inertial navigation for a spinning projectile is provided. In one embodiment, a navigation system comprises: a strapdown navigation processor; a propagator-estimator filter, the processor inputs inertial sensor data and navigation corrections from the filter to generate a navigation solution comprising projectile velocity and attitude estimates; an upfinding navigation aid that generates an angular attitude measurement indicative of a roll angle; and a physics model performing calculations utilizing dynamics equations for a rigid body, the model inputs 1) projectile state estimates from the navigation solution and 2) platform inputs indicative of forces acting on a projectile platform, and outputs a set of three orthogonal predicted translational acceleration measurements based on the inputs; the filter comprises a measurement equation associated with the physics model and the upfinding navigation aid and calculates the navigation corrections as a function of the navigation solution, the predicted translational acceleration measurements, and attitude measurement.

An inertial measurement system for a spinning projectile includes: a first, roll gyro to be oriented substantially parallel to the spin axis of the projectile; a second gyro and a third gyro with axes arranged with respect to the roll gyro; a controller, arranged to: compute a current projectile attitude from the outputs of the first, second and third gyros, the computed attitude comprising a roll angle, a pitch angle and a yaw angle; calculate a roll angle error; provide the roll angle error as an input to a Kalman filter that outputs a roll angle correction and a roll rate scale factor correction; and apply the calculated roll angle correction and roll rate scale factor correction to the output of the roll gyro.

A system and method for state estimation in spinning projectiles is provided. The state estimation is based, at least in part, on magnetic sensor data, angular velocity data, and correction terms applied to the magnetic sensor data and the angular velocity data. The system and method for state estimation in spinning projectiles estimates roll angles and roll rates of the spinning projectiles. The roll angle and roll rate estimates allow steering commands to be applied to steer the spinning projectiles in the proper direction.

A system and method for state estimation in spinning projectiles is provided. The state estimation is based, at least in part, on magnetic sensor data, angular velocity data, and correction terms applied to the magnetic sensor data and the angular velocity data. The system and method for state estimation in spinning projectiles estimates roll angles and roll rates of the spinning projectiles. The roll angle and roll rate estimates allow steering commands to be applied to steer the spinning projectiles in the proper direction.

A real-time compensation system of a projectile includes at least one flight controller, at least one imager device, at least one gyroscope, and at least one processor. The at least one flight controller is configured to rotate the projectile about an axis between a first orientation and a second orientation. The at least one imager device is configured to capture a first image at the first orientation and a second image at the second orientation. The at least one gyroscope is configured to sense a first angular rate of the projectile as the projectile rotates from the first orientation to the second orientation. The at least one processor is configured to determine a first rotation angle based upon the first and second images and a second rotation angle based upon the angular rate sensed by the at least one gyroscope, and determine a gyroscope compensation parameter.

Techniques are provided for determination of a guided-munition orientation during flight based on lateral acceleration, velocity, and turn rate of the guided-munition. A methodology implementing the techniques, according to an embodiment, includes obtaining a lateral acceleration vector measurement and a velocity of the guided-munition, and calculating a ratio of the two, to generate an estimated lateral turn vector of the guided-munition. The method also includes integrating the estimated lateral turn vector, over a period of time associated with flight of the guided-munition, to generate a first type of predicted attitude change. The method further includes obtaining and integrating a lateral turn rate vector measurement of the guided-munition, over the period of time associated with flight of the guided-munition, to generate a second type of predicted attitude change. The method further includes calculating a gravity direction vector based on a difference between the first and second types of predicted attitude change.

An inertial measurement system comprising: a first, roll gyro with an axis oriented substantially parallel to the spin axis of the projectile; a second gyro and a third gyro with axes arranged with respect to the roll gyro; a controller, arranged to: compute a current projectile attitude from the outputs of the first, second and third gyros; operate a Kalman filter that receives a plurality of measurement inputs including at least roll angle, pitch angle and yaw angle and that outputs at least a roll angle error; initialise the Kalman filter with a roll angle error uncertainty representative of a substantially unknown roll angle; generate at least one pseudo-measurement from stored expected flight data; provide said pseudo-measurement(s) to the corresponding measurement input of the Kalman filter; and apply the roll angle error from the Kalman filter as a correction to the roll angle.

A device, system, and method for shaping the trajectory of a projectile employing a Gravity bias, Gbias. The system includes a seeker, a guidance filter, a pitch rate filter, an actuator, pitch/yaw/roll coupled aerodynamics, and lateral rate sensors. It receives roll orientation input to a guidance and control autopilot; it applies Additional Gbias to that produced by the null rate command to the lateral control loops of the guidance and control autopilot device. The lateral rate command is equal to the desired Additional Gbias divided by an estimate of the projectile velocity. The Additional Gbias is translated to a rate command and incorporated into guidance loop commands to boost an Inherent Gbias to shape the trajectory of the projectile to the target.