Position Sensor Technology for Hydraulic Cylinder Feedback

Position feedback sensors for hydraulic or pneumatic cylinders have used one of three traditional technologies: magnetostrictive, variable resistance, and variable inductance. As the demand for increased control and functionality has increased, sensor-instrumented cylinders are becoming more important in the heavy industry, subsea, and mobile equipment worlds. Ultimately, a user or systems integrator must determine the requirements of the application and which technology best satisfies it on a total installed cost versus performance basis. The strengths and weaknesses of magnetostrictive, variable resistance, and variable inductance sensors are shown in the figure. These common sensing technologies utilize a long probe that extends into a deep, small-diameter blind hole that has been gun-drilled into the internal end of the cylinder rod.