Inductive Strain Sensor with High Repeatability and Ultra-Low Hysteresis Based on Mechanical Spring

Soft sensing is an essential technology to soft robots, such as soft manipulators and soft locomotion robots want to perceive the morphology of its bodies. Resistance-based and capacitance-based soft sensing has been widely reported in recent years, but inductance-based soft sensing has been reported only a few times. In this paper, soft sensing with large strain is demonstrated by utilizing inductance variation. The basic idea is to fabricate inductance like a mechanical spring by the fibers, which is both very flexible and very sensitive to strain variation. The inductance-based soft strain sensing fibers can be embedded inside soft robots, or can even be incorporated into existing robotic elements, such as replacing the restriction fibers in the air channels of pneumatic actuators. The sensing technology proposed in this work demonstrates very high repeatability and ultra-low hysteresis.