Preliminary Evaluation of an Embedded FBG-Based Force Sensor for In-Hand Grasp Monitoring

During the object grasping process, variations in actual and calculated contact point location can occasionally occur. These variations are attributed to overestimations, manipulator dynamics, calculation errors, environmental factors, or the shape of the object. To mitigate this issue and facilitate continuous in-hand grasp monitoring an embedded Fiber Bragg Grating (FBG)-based force sensor was developed with low latency and high sensitivity. This paper presents preliminary findings on the material selection and the correlation between applied contact force with the sensor response. This sensor has been designed for monitoring continuous grasp quality across multi-finger grasps. A systematic set of experiments was conducted with the assistance of a robotic manipulator. The experiment involved applying a constant travel distance of the probe relative to the gripper finger to record the corresponding wavelength response. Our results indicate the sensor’s behavior with two different embedded materials with Shore A hardness of 28 and 55. The harder material exhibited greater sensitivity and coverage. Additionally, an excellent correlation and linearity between the forces applied on the sensor and the corresponding sensor wavelength was discovered. Future research will aim at the grasping force localization relative to the sensor.