Servo Hydraulic Shaker System
Servo hydraulic shaker systems are advanced test systems that apply vibration, shock, or controlled mechanical loads by managing hydraulic energy with high precision. By controlling hydraulic power on a closed-loop basis, these systems offer significantly higher accuracy, repeatability, and dynamic performance than conventional hydraulic systems. Through servo valves and feedback sensors, system behavior is continuously monitored and corrections are made within milliseconds based on the target signal.
Servo hydraulic shaker systems are especially preferred for high-mass test specimens, test scenarios requiring low frequency and high displacement, and long-term structural durability and fatigue testing. Thanks to their closed-loop control architecture, the system can run in force-controlled, displacement-controlled, or acceleration-controlled modes, adapting flexibly to different test scenarios. This makes it possible to simulate complex load profiles and real operating conditions in the laboratory with high accuracy.
The basic working principle of servo hydraulic shaker systems relies on the precise direction of hydraulic energy. The system is built from four main components: a Hydraulic Power Unit (HPU) that generates high-pressure hydraulic oil, servo valves that control oil flow with millisecond precision, a hydraulic actuator (cylinder) that converts hydraulic pressure into linear mechanical motion, and a PID-based controller that manages system behavior according to the target signal. During testing, system performance is continuously measured through LVDT displacement sensors, load cell force sensors, and accelerometers. The feedback data from these sensors is evaluated by the controller in real time, and the system output is adjusted to match the target test signal.
Thanks to high control precision, broad load capacity, and realistic load simulation, servo hydraulic shaker systems are widely used in many critical engineering applications, including chassis and suspension durability tests in the automotive sector, landing gear and structural component tests in aerospace and defense, dynamic behavior simulation of bridges and large structures, durability validation tests of large-scale military equipment, and long-term fatigue tests. These systems are considered one of the core infrastructures of modern test laboratories for verifying product durability under real operating conditions and improving design reliability.
Hydraulic Power Unit (HPU)
The Hydraulic Power Unit (HPU) is the energy source of a servo hydraulic shaker system. It generates the high-pressure hydraulic oil required by the system and supplies it continuously to the circuit. Made up of a pump, oil tank, filters, cooling system, and pressure control elements, the HPU provides the hydraulic power needed for the system to operate stably and reliably.
Servo Valve
Servo valves are the main control elements that allow hydraulic flow to be controlled with very high precision. They convert electrical command signals from the controller into hydraulic flow, adjusting the direction and rate of oil flow. Capable of responding within milliseconds, servo valves are one of the most critical components in determining the system’s dynamic performance and precision.
Hydraulic Actuator (Cylinder)
The hydraulic actuator is the component that converts the hydraulic pressure directed by the servo valves into linear mechanical motion. The force, displacement, or vibration motion applied to the test specimen is generated by this actuator. The actuator’s capacity directly affects the maximum force, displacement, and dynamic performance the system can deliver.
Controller (PID Control System)
The controller is the electronic control unit that manages all operating behavior of the servo hydraulic shaker system. Using a PID (Proportional–Integral–Derivative) control algorithm, it continuously calculates the difference between the target test signal and the measured system output, and applies the necessary corrections through the servo valves. This way, the system can follow the desired force, displacement, or acceleration profile with high accuracy.
Feedback Sensors
High-precision control in servo hydraulic systems is made possible by feedback sensors. These sensors measure the system’s instantaneous behavior and provide data to the controller. The data they produce is continuously analyzed by the controller for closed-loop control, and the system output is adjusted precisely to match the target test signal.
LVDT (Linear Variable Differential Transformer)
An LVDT is a contactless position sensor used in servo hydraulic shaker systems to measure linear displacement with high precision. It continuously monitors the motion of the actuator piston and provides the system’s instantaneous position to the controller. Its contactless operating principle delivers high accuracy, long service life, and stable measurement performance. The displacement data obtained allows the closed-loop control system to follow the target motion profile precisely.
Load Cell (Force Sensor)
A load cell is a precise force sensor used to measure the force applied to the specimen during testing. It converts mechanical force into an electrical signal and sends it to the control system, allowing the applied load to be monitored in real time. The accuracy of force-controlled tests in servo hydraulic systems depends largely on load cell measurements. Thanks to their high accuracy and reliability, these sensors keep the applied force at the target values throughout the test.
Accelerometer
Accelerometers are sensors used to measure vibration and acceleration values on the system or the test specimen. In dynamic tests, especially in vibration and shock applications, they are critical for determining the system’s actual behavior. The data from accelerometers is used to analyze the acceleration levels generated during the test and to ensure that the control system applies the target vibration profile correctly.