Integrated fuzzy guidance law for high maneuvering targets based on proportional navigation guidance

An integrated fuzzy guidance (IFG) law for a surface to air homing missile is introduced. The introduced approach is a modification of the well-known proportional navigation guidance (PNG) law. The IFG law enables the missile to approach a high maneuvering target while trying to minimize control effort as well as miss-distance in a two-stage flight. In the first stage, while the missile is far from the intended target, the IFG tends to have low sensitivity to the target maneuvering seeking to minimize the overall control effort. When the missile gets closer to the target, a second stage is started and IFG law changes tactic by increasing that sensitivity attempting to minimize the miss-distance. A fuzzy-switching point (FSP) controller manages the transition between the two stages. The FSP is optimized based on variety of scenarios; some of which are discussed in the paper. The introduced scheme depends on line-of-sight angle rate, closing velocity, and target-missile relative range. The performance of the new IFG law is compared with PNG law and the results show a relative superiority in wide variety of flight conditions.