Guidance Navigation and Control Algorithms for High Dynamics Vehicles

Abstract

Accuracy and precision are the cornerstone for ballistic projectiles from the earliest days of this discipline. In the beginnings, impact point precision in artillery devices deteriorated when range was extended, particularly for ballistic artillery rockets and shells, which are not propelled except during the launch. Later, inertial navigation and guidance systems were introduced and precision was unlinked from range increases. In the last thirty years, hybridization between inertial systems and GNSS devices has improved precision enormously. Unfortunately, during the last stages of ight, inertial and GNSS methods (hybridized or not) feature big errors in attitude and position determination. Low cost devices, which are precise on terminal guidance and do not feature accumulative error, such as quadrant photo-detector, seem to be appropriate to be included in the guidance systems. Hybrid algorithms, which combine GNSSs, IMUs and photo-detectors, are required to implement these novel techniques. The acceleration autopilot with a rate loop is the most commonly implemented autopilot, which has been extensively applied to high-performance missiles. Nevertheless, for high speed spinning rockets, the design of the guidance and control modules is a challenging task because the rapid spinning of the body creates a heavy coupling between the normal and lateral rocket dynamics. Hybridized measurements are implemented in modi ed proportional navigation law and a rotatory force control method. A realistic non-linear ight dynamics model, particularized for a high spinning ballistic rocket, has been developed to perform simulations to prove the accuracy of the presented algorithms. The research process developed to obtain the nal results implied the following steps: 1. The development of a ight model in order to simulate the dynamics of a highly spinning rocket which features a decoupled fuse. 2. The development of a novel 3D guidance law, based on a modular rotatory force, for gyroscopically stabilized artillery rockets (i.e., spin rates in the hundreds of rotations per second during the launch), which is derived from proportional navigation. 3. A model for a quadrant photo-detector based on a real-time area intersection algorithm was developed and the subsequent development of a novel algorithm which improves the precision of spot center determination for a Semi-active Laser quadrant detector in the terminal guidance of artillery rockets. 4. The integration of this photo-detector spot center determination algorithm and the hybridization with GNSS/IMU in order to improve the precision of the line of sight. 5. The development of an algorithm, based on an estimation method in order to obtain the gravity and velocity vectors in a di erent pair of triads, which aims at avoiding gyroscopes for attitude determination. 6. The integration of these attitude determination methods together with the aid of ltering techniques, into the previously photo-detector, GNSS, IMU, and control rotatory force, developed algorithms. Finally, nonlinear simulations based on ballistic rocket launches were performed to demonstrate the applicability of the proposed solution for ight navigation, guidance and control, for ballistic rocket terminal guidance.