Control of Linear Hydraulic Actuator using the full Hydraulic Bridge

Control of the linear hydraulic actuator using the full hydraulic bridge is the main topic of this paper. The Linear hydraulic drives are often used in production machines, technological equipment, robots and manipulators for their high power-mass ratio and ability to manipulate with big masses and produce bid forces by very small velocities. Very often both tasks are required - movement with mass and producing high force, as well as achieving the given position with high accuracy at the end of the trajectory. Also force control can be demanded. The desired properties are realized by the control of the hydraulic drives using the hydraulic circuits with servo valve, and for special functions, additional parts of the hydraulic circuit must be designed and used. The paper presents the control of the hydraulic linear drive using the full hydraulic bridge realized using four proportional valves, which represent four-variable hydraulic resistances controlled by the separate four control signals. The designed and realized hydraulic actuator, control algorithms, control system and results from the experiment on the test rig are introduced in the paper.