Control system for hybrid vehicle

A control system in a hybrid vehicle having an engine for producing propulsive forces, an electric motor for selectively assisting drive forces in addition to the propulsive forces and generating electric energy converted from the propulsive forces, and an energy storage unit for selectively supplying electric energy to the electric motor and storing electric energy converted by the electric motor, comprising:

• idling state detecting means for detecting an idling state of the engine;
• rotational speed variation detecting means for detecting a rotational speed variation of the engine in the idling state of the engine;
• fuzzy inference memory means for storing a plurality of fuzzy rules and membership functions to determine an operating state of the electric motor to suppress the rotational speed variation of the engine from said detected rotational speed variation of the engine according to a fuzzy inference process;
• goodness-of-fit calculating means for determining respective goodnesses of fit of said fuzzy rules based on said membership functions from the rotational speed variation of the engine as detected by said rotational speed variation detecting means in the idling state of the engine as detected by said idling state detecting means;
• goodness-of-fit combining means for combining the goodnesses of fit as determined by said goodness-of-fit calculating means to determine an operating state of the electric motor;
• and
• motor control means for controlling the electric motor based on the operating state of the electric motor as determined by said goodness-of-fit combining means.