Servohydraulic

A servohydraulic system is a servo-controlled hydraulic actuation system that provides high force and precise motion control by regulating hydraulic fluid flow through a servo valve in response to an electronic command. It combines hydraulic power with closed-loop electrical control to achieve accurate positioning, speed, or force in a compact package.

Core components include a servo valve (often a proportional or servo valve), a hydraulic pump and reservoir, hydraulic actuators such as cylinders or hydraulic rams, and the hydraulic fluid itself. The system also incorporates sensors such as position transducers, force sensors, or pressure transducers, along with a controller and signal amplifiers to form a closed feedback loop.

Operation relies on converting a command signal from a controller into a variable flow through the servo valve. The resulting fluid pressure and flow move the actuator, while sensors provide real-time feedback on position or force. The controller compares the feedback with the command and adjusts the valve to reduce error, typically using control strategies such as PID or more advanced model-based algorithms to achieve desired performance.

Applications of servohydraulic systems are widespread in testing and manufacturing. They are central to material testing machines (universal testing machines), aerospace and automotive component testing, civil engineering and structural testing, dynamic vibration testing, and certain robotic or precision positioning tasks where high force and stiffness are required.

Advantages include high force density, fast dynamic response, high stiffness, and good force/velocity control over a wide range. Limitations involve system complexity, potential hydraulic fluid leaks, temperature sensitivity, maintenance requirements, and control stability issues arising from valve dynamics and fluid characteristics. Proper design emphasizes fluid cleanliness, thermal management, and robust control strategies.