Fuzzy logic PID controller for missile terminal guidance

Demonstrates fuzzy logic terminal guidance for a surface-to-surface missile. A conventional proportional-integral-derivative (PID) guidance scheme is first employed to form the basis for the fuzzy terminal guidance. The PID guidance scheme employs heading and flight path angle errors derived from sensor imagery of target location to compute angular rate commands. The fuzzy logic terminal guidance design procedure involves translating the conventional PID guidance scheme into a fuzzy control structure with the associated fuzzification of input/output variables, encoding of decision-making knowledge into rulebases, and defuzzification. A novel scheme is implemented in which fuzzy rulebases are used to generate and combine PD and PI portions of the guidance commands. Additionally, the fuzzy terminal guidance includes rulebases to control speed and to perform gain scheduling. Performance evaluations demonstrate the feasibility of the approach.