• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.156-160
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• 1997

This paper introdues the development of hydraulic cylinder with magnetic sensor detecting absolute and precise position for automation of excavator. The system which is developed can detect absolute position witha little displacement by using algorithm for recognizing datum points, 1/4 divider algorithm and high precision algorithm improved position precision and robustness to noise etc. The solenoid valve and PWM control using saw-toothed wave are used for absolute position control of cylinder, respectively

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.68-75
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• 2003

This paper introduces the development of hydraulic cylinder with magnetic sensors detecting absolute and precise position for automation of excavator. The system which is developed can detect absolute position with a little displacement by using algorithm for recognizing datum points, 114 divider algorithm and high precision algorithm improved position precision. We alse evaluate the developed system under the load disturbance and add band pass filter to the previous's signal process circuit for the protecting magnetic sensors's saturation.

• Journal of IKEEE
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• v.19 no.3
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• pp.335-341
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• 2015

Recently a demand for high precision absolute position transducer is increasing in order to control thickness in steel industry. LVDT (linear variable differential transformer) is widely used to measure the absolute position in the linearly moving cylinder under poor factory environment. In this paper we implement the three phase LVDT with a high resolution of one micron and L/D (LVDT to digital) converter. First we designed U, V, and W three phase signaling using FPGA. Second a pulse output algorithm is designed for position information with A and B phase waveforms. Finally the performance is compared with previous sensors. Experiments show that the linearity deviation error is 0.009788 [mm] and the average sinusoidal THD is 0.0751%, which means 2.2% and 33% more improved result than the previous sensors respectively.