Long seek control system and method thereof used in optical information reproduction/recording system

A long seeking control system for an optical information reproduction/recoding system comprising a lens and a sledge, comprising:

• a second order observing unit, generating a sledge estimation displacement signal and a sledge estimation velocity signal, and further generating the sledge estimation velocity and the sledge estimation displacement by a first open loop control or a first close loop control according to the generated the sledge estimation velocity;
• a jump profile generator, generating a sledge reference velocity signal according to the sledge estimation displacement signal;
• a gain control unit, generating a first force applied to the sledge according to the sledge estimation velocity signal and the sledge reference velocity signal;
• and
• a lens controller, generating a second force applied to the lens according to the sledge estimation velocity signal and the first force signal, and generates the second force applied to the lens by a second open loop control or a second close loop control according to the sledge estimation velocity.