Electro-hydraulic servo actuator is the loading element of the geotechnical engineering test system. According to the different structural forms and uses, in addition to the four electro-hydraulic servo actuators of the structural test system in the Popwil geotechnical test system, a special actuator for geotechnical test is also designed: surface load actuator. This type of actuator does not have a displacement sensor and a load sensor, but high-precision oil pressure sensors are installed at the front and rear chambers of the actuator. The thrust of the actuator can be calculated from the measured hydraulic pressure and the area of the rod cavity and rodless cavity of the actuator piston.
