servo drive

Hydraulic Servo Drive Systems: An Understanding of the Operational Principle and Fields of Application

Hydraulic servo drive systems are one of the most important components in precise control requiring industrial applications regarding hydraulic actuators. They combine powerful operation mechanisms with high precision in servo control, giving them unique performance characteristics in terms of accuracy, responsiveness, and force.

Hydraulic Servo Drive Systems is an advanced form of hydraulic system that applies servo control technology to manipulate the performances of hydraulic actuators.

Hydraulic Servo Drive Systems Unlike the conventional hydraulic systems, which work strictly by a fixed pressure and flow rates, the hydraulic servo drive systems work by feedback for highly controlled position, speed, and force parameters.

Components of a Hydraulic Servo Drive System

  • Servo Valve: The heart of the hydraulic servo drive system is the servo valve. It controls the flow and pressure of the hydraulic fluid towards the actuator but is regulated by input signals that come from the control system.
  • Hydraulic Actuator: The hydraulic cylinder or motor, converts energy available in hydraulic form into mechanical power. The actuator follows the command signal which is received by the control system from the servo valve to actuate the desired motion.
  • Control System: Programmable Logic Controller (PLC) or Micro-controller are used to control the output signal. The control system received the command signal from the sensors as feedback signals, and PLC or Micro-controller compared the feedback signal with the desired value. Generate the error signal, This error signal is sent to the Servo valve.
  • Sensors: Linear Variable Displacement Transducers (LVDT), Rotary encoders, or Pressure transducers that generate real-time data to measure the displacement, speed, and force developed by the actuator.

Working of Hydraulic Servo Drive System:

The control system generates a command signal corresponding to the desired position, velocity or force of the hydraulic actuator. The command signal is an electrical signal representing the target value.

  • Signal Processing by Servo Valve: The command signal is received by the servo valve, and the controller generates the signal which is used to adjust the volumetric flow as well as pressure in the hydraulic system. It modulates fluid flow to the actuator with precision to control the movement of the actuator.
  • Feedback Loop: There are feedback loop system is used that will constantly monitor the real-time position, speed, and force of the actuator. And this feedback signal is used by the control system.
  • Error Calculation and Correction: The control system calculates errors in between the Desired value and the actual value. Based on that error, the command signal gets manipulated to the servo valve by the control system in such a manner that the actuator will move with the desired motion, thereby providing high-precision control.

Advantages of Hydraulic Servo Drive Systems

  • High precision and control: This is the feature that distinguishes hydraulic servo drive systems from regular hydraulic systems; more precision and control can be achieved using the feedback loop and hydraulic servo system.
  • High Responsiveness: The system is ensured through feedback control with the help of servo valves, which produces better responses for command signals, all this altogether leads to better efficiency in system performance.
  • Versatility: The systems find an application not only in industrial automation and robotics but in aerospace and defences as well. Its high level of energy efficiency is there due to advanced control algorithms and accurate modulation of hydraulic flow and pressure.

Application of Hydraulic Servo Drive Systems

  • Industrial Automation: Applied where rigid control is applied in equipment such as hydraulic presses and injection molding machines, among many others.
  • Robotics: Used to control the movements of robotic arms and actuators on hydraulic robots used in industries and other areas of manufacture.
  • Aerospace and Defence: Such equipment is used in flight simulation, aircraft control, and other military equipment that requires motion control to be detailed, reliable, and precise.
  • Construction and Heavy Machinery: For precise movement and operational control for every kind of operation related to heavy machinery excavators, cranes etc. hydraulic servo system is used.
  • Marine and Offshore: Utilized on marine and offshore drilling platforms for controlling winches, cranes, and other hydraulic machinery.
  • Medical Equipment: In medical machinery that requires smooth and precise control of movement, such as surgical robots and patient positioning systems.


Hydraulic servo drive systems are considered the pinnacle of hydraulic technology: hydraulic power combined with precise control. With the knowledge of the principles of operation and benefits, the industries can employ the systems to get maximum performance, great efficiency, and high accuracy in use across many applications. Thanks to advanced technology, hydraulic servo drive systems are well on course to become an ever more important element within industrial automation and motion control.

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