A NEW THIN PICKUP COIL FOR MAGNETIC HEAD TYPE TORQUE SENSORS

A new thin pickup head is proposed for magnetic head type torque senso rs. The new pickup head consists of a stacked pair of figure 8 coils, in which one of the coils is rotated in the coil plane by 90-degrees f rom the other. The applied torque can be detected from the difference in self-inductances of a pair of the figure 8 coils faced to the shaft through an air gap in a manner that each figure 8 coil sees the perme ability of the shaft along either 45-degrees or -45-degrees from the a xis. Unlike conventional pickup heads of 3-D structure, the proposed p ickup head is thin, hence making it easy to build the torque sensor on a shaft. Experimental results using a magnetic yoke backing the picku p head showed a good linearity with small hysteresis.