Most of the robot arms currently in use consist of an electromagnetic motor and a reduction gear. However, they are not suitable for use in environments such as construction sites. In order to solve this problem, a compact and high-torque hydraulic robot arm was developed in our laboratory. In this study, we aim to apply this robot arm to collaborative work with an operator. The objective of this study is to achieve intrinsic safety by limiting the flow of oil into the motor By inserting an orifice between servo valve and motor, we achieved restricting the maximum speed of motor, keeping the maximum torque. This design is based on the unique principle of hydraulics, where the speed and force are independently determined by flow rate and pressure. In the future, we plan to implement the orifice plates in the 7-axis robot arm, aiming to apply it to actual heavy-duty work.
