Design and control of multi-degree-of-freedom shroud nozzle hydraulic manipulator in steel manufacturing

This paper presents the design and control of multi-degree-of-freedom (DOF) hydraulic manipulator for the steel-manufacturing work flow automation in continuous casting. This manipulator is aimed at handle a heavy-weight shroud nozzle autonomously in hazardous circumstances around the ladle. The half-sized miniature shroud-nozzle manipulator platform was manufactured, where it is operated by hydraulic-powered actuators. Three rotary and two linear hydraulic actuators compose 5-DOF manipulator and it can generate a stable 800 N tightening force to upright. Each joint link includes a 1-DOF joint torque sensor and encoder, which measure the contact force with the collector nozzle. Since hydraulic actuators can support heavy-weight loads such as shroud nozzles with relatively compact volume, it is suitable for applying in the steel manufacturing processes that allow restricted working spaces. Position-based control method is used for the shroud nozzle to approach the collector nozzle. After contacting two nozzles, the force controller based on a force integral control is applied. Integral equation based controller tends to reduce a force error in process of time. The results of simulation and experiment showed that this manipulator is qualified to satisfy use.