Development of a Soft Haptic Sensor Capable of Measuring Contact Forces Based on Magnetorheological Elastomers

Soft haptic sensors play an important role in gauging haptic interaction in human collaborative robotics and physical rehabilitation. Currently available sensors are difficult to use in real-world applications where low magnitude forces need to be measured, or where the sensor must be attached to the highly curved surface of the human body or robotic arm. Therefore, this paper proposes a new soft haptic sensor that can be used in such applications. In the proposed sensor we have used MRE (Magnetorheological elastomer) to transform the ‘non-characteristic magnetic fluxes’ generated by 4 permanent magnets into a ‘vector-characteristic cluster’ the directionality of which is dependent on the location of application of the external force. This allows us to estimate the location and magnitude of the applied force. In addition, the sensor is built on an FPCB (Flexible PCB) to allow it to have robust properties even when it is used in rough situations where it must be attached to surfaces with different geometries and is subjected to high external forces. The results of the sensor capability verification experiments show that the soft haptic sensor has an acceptable level of performance when subjected to an external force of 1.2~2.0 kgf.