Abstract
Recently, due to the development of automation technology, torque measuring and monitoring technologies have been brought to the focus. However, the commercially available sensors have the disadvantage of large volume, which results in the difficulty of installation on existing automated machines. Responding to the above-mentioned problem, a contactless torque sensor that uses an electromagnetic coil combined with a permanent magnet was proposed. By adjusting the input electric current in the coil, the strength of the magnetic field can be controlled to generate a non-contact magnetic force to resist external torque loading. For the measurement of such a magnetic force, a cantilever-beam mechanism comprising a piezoelectric-loading (PZT-L) sensor is employed to estimate the external static force by measuring the variation of the electric impedance. According to the measured results, the proposed PZT-L sensor demonstrates the accuracy of the proposed design, for which the maximum estimated error was around 6%. Finally, the proposed contactless torque sensor with 11 cm in diameter and 2 cm in thickness was employed to verify the effectiveness of theoretical analysis. From the sensor characteristic measurement, the detection range for external torque can be from 7.8 to 125.6 N-mm when the driven current input ranged from 2 to 10 A. Therefore, the experimental results presented that the moment of inertia via the resisted torque can be adjusted by the proposed non-contact torque-sensing system according to the measuring condition.
Highlights
To reduce production costs and manpower resources, intelligent automated manufacturing has been actively developed
In a traditional rotating-torque sensor, two electric coils are placed oppositely in the radial direction, which induces an electric current when two of the electrical coils have an angle offset by the external toque loading [1]
Regarding the generally driven principle of the torque sensor, after the external torque load is applied in the internal shaft in the sensor, a torsion angle will be generated
Summary
To reduce production costs and manpower resources, intelligent automated manufacturing has been actively developed. Inducing a sufficient output voltage from the electrical coil is difficult, and commercial rotating torque sensors have the disadvantage of large dimension in the axial direction; as such, assembly into available production equipment is problematic. To improve the wiring issue and generate a contactless magnetic force, when the inner ring with the helical induction coil is fixed, the external torque load is applied on the outer ring to bring on the rotation, and it can be resisted by the repulsive force depending on the interval distance of the magnets, for which the relationship is similar to the spring force. Because the coupling magnetic field can be controlled by the electric current of the induction coil and interval distance between two of the magnetic poles, the designed torque sensor demonstrates the dynamic variable characteristics in the moment of inertia that the resisted torque can be adjusted according to the measuring condition
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