Dynamic Properties of a Hydraulic Servo Actuator Flexibly Connected to a Load Mass Excited by Cyclic Force

Abstract

The study deals with the dynamic properties of a hydraulic servo actuator (HSA) with flexible mounting connections. This problem is considered in two cases: firstly, in the flexible (or non-rigid) mounting connection of the barrel and piston rod of a hydraulic actuator, and secondly, in the vibration isolation of a hydraulic actuator loaded with cyclic force. The difficult and complex dynamic problem of an HSA flexibly connected to a load mass excited by the impact force generated by a rock breaker was primarily analysed. The solution of a new design of the 3-DoF hydraulic boom manipulator used to move a medium-sized hydraulic rock breaker was presented. The HSA is rigidly mounted to the mother boom, and the piston rod is flexibly connected to the inner boom via a spring-damping device (SDD), which, in this case, serves as a vibration isolator. Simulation tests based on the HSA mathematical model enabled comparison of the dynamic responses of the hydraulic actuator rigidly connected and flexibly connected via an SDD to a load mass excited by the constant and impact force generated by a rock breaker. The experimental studies on the test stand focused on HSA adaptive positioning control. The main task was to adapt the adaptive position controller to the identified HSA loaded with excitation force (impact force). The simulation and experimental tests carried out are important for assessing dynamic properties and designing the position controller of an HSA subjected to cyclic impact forces. The presented results are also important for the development of guidelines for the safe operation of various large-scale heavy hydraulic machines under vibration loads.