CAN bus applied on hydraulic computed force control

Abstract

The application range of fluid power is very wide, from fast and light pneumatic applications to heavy hydraulic applications. Control systems have been used in efforts to overcome the drawbacks in fluid power systems. This means more integrated electronics in components like valves, pumps and actuators. The acceptance of field buses within hydraulic systems is restricted because of the special nature of the hydraulics market. Due to limited space in the electronics housing and the extremely harsh environment to which valves are typically exposed, the integration of the required electronics is demanding. In this study, the CAN bus is used in a hydraulic motion control system in forward and feedback loops. The motion controller is realized with a so-called computed force controller. Good steady-state and dynamic performance, as well as high efficiency, are features that are required for with this kind of a control system. The positioning and stroke-time accuracy as well as dynamic behaviour are compared between the traditional method and different methods using the CAN bus. The influence of the baud rate of the CAN bus on the performance of the studied servo system is analysed. Theoretical background is presented and experimental results are shown.