1995 Volume 57 Issue 4 Pages 59-66
To handle heavy materials, we have developed a 5-d. o. f. hydraulic manipulator with two wrist joints controlled by hydraulic proportional valves. Compared with hydraulic servo valve, the proportional valve is simpler and lower in price, but is inferior in the control performance because of its simple construction and the operating delay of the valve. Further, in handling heavy materials, the gravity prevents precise position control. In this study, we designed a position control system to compensate the valve delay and the effect of gravity, and examined the repeated positioning accuracy and the trajectory tracking control. It was found that the system could control the position with the same accuracy as by the servo valve.
