High Sensitivity and Wide Range Soft Magnetic Tactile Sensor Based on Electromagnetic Induction

Tactile sensors play a significant role in robotic systems to interact with the external world. In this article, a novel soft magnetic tactile sensor (SMTS) based on the law of electromagnetic induction is proposed. This new sensor uses the configuration of a transformer with planar coils and a Polydimethylsiloxane silicone elastomer with an inverted cone structure embedded in a copper sheet. The SMTS measures the induced voltage amplitude variation of the secondary coil that is caused by the changes in alternating current magnetic field between the coil and the conductive or ferromagnetic sheets. The principle of the new sensor is explained first and then the design methods are outlined. Prototypes are manufactured and a three-dimensional finite element model is built to analyze the mechanical property of the elastomer. Besides, a performance analysis platform and an electronic interface system with the excitation source, the signal processing and the data acquisition, are developed, in order to calibrate the sensor using the polynomial fitting method. The calibrated prototype shows competitive performances in comparison with other existing counterparts, which has a high sensitivity of 56.3 mV/N, a wide measurement range up to 15 N, and a low hysteresis of 2.02%. The new sensor is also of low cost, durable, and has potential applications in dexterous robotic manipulation.