This study describes a hydraulic fluid property compensator under the various operating conditions. Because hydraulic fluid systems have much more excellent features than other control systems, they are used in many fields. However, the characteristics of hydraulic fluid are changed due to various operating conditions. This phenomenon is called uncertainty. Especially, bulk modulus is considered as the most dominant parameter in this study. In order to overcome the uncertainty ∞ control technique will be used for this study. Designed controller using the ∞ control technique, is adopted for the hydraulic fluid multistage double acting oil pressure cylinder. Repetition operation test gives from 5 to 8 percent errors in moving position.

Abstract
 1. 서 론
 2. 적용 이론
  2.1 체적 탄성계수(Bulk modulus)
  2.2 모델-매칭 문제(Model-matching problem)
  2.3 콘트롤러 파라메트리제이션(Controller parametrization)
 3. H∞ 알고리즘
  3.1 수정된 문제(Modified problem)
  3.2 수정된 문제의 해(Solution of modified problem)
 4. 시스템 모델링과 제어기 설계
  4.1 밸브 모터 조합(Valve-motor combination)
  4.2 콘트롤러 설계
 5. 제어장치의 다단 복동 유압실린더 적용
  5.1 다단 복동 유압실린더의 구성 및 제작
  5.2 제어장치의 다단 복동 유압실린더 적용
 6. 결 론
 참 고 문 헌

• 황규동(충주대학교 에너지시스템공학과) | K. D. HWANG
• 김도석(유한대학 기계설계과) | D. S. KIM
• 임대성(주성대학 자동차과) | D. S. LIM