Hardware in Loop Simulation for Missile Guidance and Control Systems

The purpose of the guidance law is to determine appropriate missile flight path dynamics to achieve mission objective in an efficient manner based on navigation information. Today, guided missiles which are aerodynamically unstable or non-linear in all or part of the flight envelopes need control systems for stability as well as for steering. Many classical guidance and control laws have been used for tactical missiles with varying degrees of performance, complexity and seeker/sensor requirements. Increased accuracy requirements and more dynamic tactics of modern warfare demand improvement of performance which is a trade-off between sophisticated hardware and more sophisticated software. To avoid increase in cost by hardware sophistication, today's trend is to exploit new theoretical methods and low cost high speed microprocessor techniques. Missile test flights are very expensive. The missile system with its sophisticated software and hardware is not reusable after a test launch. Hardware-in-loop Simulation (HILS) facilities and methodology form a well integrated system aimed at transforming a preliminary guidance and control system design to flight software and hardware with trajectory right from lift-off till its impact. Various guidance and control law studies pertaining to gathering basket and stability margins, pre-flight, post-flight analyses and validation of support systems have been carried out using this methodology. Nearly full spectrum of dynamically accurate six-degrees-of-freedom (6-DOF) model of missile systems has been realised in the HILS scenario. The HILS facility allows interconnection of missile hardware in flight configuration. Pre-flight HILS results have matched fairly well with actual flight trial results. It was possible to detect many hidden defects in the onboard guidance and control software as well as in hardware during HILS. Deficiencies in model, like tail-wag-dog (TWD), flexibility, seeker dynamics and defects in the guidance and control system were demonstrated in HILS. Appropriate design modifications were introduced and tested in record time to reduce the number of expensive flight trials