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.

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.

A computer-implemented method of training a machine learning, ML algorithm to control spin-stabilized steerable projectiles is described. The method comprises: obtaining training data including respective policies and corresponding trajectories of a set of spin-stabilized steerable projectiles including a first projectile, wherein each policy relates to steering a projectile of the set thereof towards a target and wherein each corresponding trajectory comprises a series of states in a state space of the projectile (S2001); and training the ML algorithm comprising determining relationships between the respective policies and corresponding trajectories of the projectiles of the set thereof based on respective results of comparing the trajectories and the targets (S2002).

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 method and apparatus is provided that provides accurate navigation for spin-stabilized projectiles in a GPS-denied environment using low cost measurement sensors, by application of flight dynamics in real-time state estimation algorithms.

An inertial measurement system for a spinning projectile comprising: 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 such that they define a three dimensional coordinate system; 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 based on the difference between the computed pitch and yaw angles and expected pitch and yaw angles; 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; wherein the Kalman filter models roll angle error as a function of roll rate and one or more wind variables. The system provides improved calibration of the roll axis rate gyro scale factor, e.g. of an IMU fitted to a rolling projectile. A separate process (an Euler angle filter) is used to calculate an estimate of the roll angle error without the use of the Kalman filter and is then provided as an input to the Kalman filter which can then operate in a stable manner. The filter can be configured to estimate and correct for crosswind effects which would otherwise significantly degrade performance.

Apparatus and methods for pulse error correction are disclosed. The apparatus may include a spinning vehicle having a plurality of antennas for generating pulse signals indicative of the rotational orientation of the spinning vehicle. The apparatus may utilize anti-jamming to detect and nullify a jamming signal. The apparatus may apply pulse error correction to correct inaccuracies in the pulse signals indicative of the rotational orientation of the spinning vehicle. More specifically, positional information of a source of the jamming signal relative to the spinning vehicle and positional information of a satellite relative to the spinning vehicle may be determined and utilized to calculate a rotational orientation correction.