An Induction Type Displacement Sensor used in a Novel Soft Robotic Muscle Actuator

This paper presents the development of a displacement sensor used in a novel soft robotic muscle actuator. This displacement sensor has several features over existing sensors used in soft muscle actuators such as ease of fabrication and minimal effect on the performance of the actuator. Moreover the soft actuator and the sensor is inexpensive compared to existing soft actuators and sensors. A novel inductance sensing method was used to find the displacement of the actuator which enables closed loop control of the actuator. The authors have experimentally evaluated the performance of the displacement sensor. The proposed sensor has a sensitivity of 0.00244 mu H/mm and the hysteresis is below 1.5% with average error less than 4%. Position feedback control of the actuator using built-in displacement sensor was tested and validated by controlling the actuator via a sinusoidal curve. The results suggested that this sensor can accurately measure the displacement of the said soft muscle actuator which can be used in different soft robotic applications.