Abstract: The simplicity of laser guidance systems which operate on Bang-Bang control pattern makes them have high reliability and low cost.However,the resonance of the system spreads the distribution of hitting points of the missile,hence the guidance accuracy is reduced. Introducing sliding mode into the system changes it to a sliding relay-control guidance system. So,the distrf bution is significantly compressed the guidance accuracy is enhanced,and the advantages of this kind of laser guidanee system are retained.The composition of the systems is presented,the phi-losophy of enhancing the guidance accuracy is analysed,and some simulation resuIts are shown.

Key words: laser guidance, relay control, sliding mode