This paper introduces the development of a position sensor detecting absolute and precise position of piston rod of the cylinder. In order to cope with several problem of former LVDT sensor and 4-partitioning incremental type sensors, a stroke measuring system composed of magnetic linear sensor, mechanical housing part and signal processing part, is suggested by adopting resolving method such that 1 period of sine groove is divided by 1024. By accomplishing several experiments using an implemented prototype stroke measuring system, it is verified that the proposed stroke measuring system can stably measure stroke value of hydraulic cylinder with good performance and accuracy.
This paper is composed as follows. In chapter 1, Several references are surveyed for investigating the technology about stroke measuring sensors for hydraulic cylinders. In chapter 2 the characteristics of hydraulic cylinders for offshore application. And in chapter 3, two method of stroke measurement such as LVDT and 4-partitioning incremental type sensor are surveyed in view of advantages and disadvantages. In chapter 4, the main contents of this paper, a new composition method using analog linear sensors for stroke measurement is suggested in view of hardware implementation. The method basically uses the 1024 partitioning method named resolver method for the one period of sine wave type piston rod grooves. In chapter 5, several experiments are executed by applying the implemented stroke measuring system to an offshore hydraulic cylinder for operating a water gate and the resultant data are collected and analyzed. And the stroke measurement possibility of the proposed system is addressed based on the experimental data. In chapter 6, conclusions about this paper are synthetically addressed.