Development of flexible tactile sensor for the envelop of curved robotic hand finger in grasping force sensing

Intelligent robotic hand with integrated tactile sensor is able to perform real-time tactile information sensing, which is crucial for dexterous grasping and manipulation. This paper presents a novel flexible tactile sensor with 18 sensing units to envelop a complex-shaped robotic hand finger for grasping force measurement. A new approach based on point cloud fitting and triangular searching is developed to determine the special configuration of these 18 sensing units on the complex finger surface, and it is used for the structural design of the flexible tactile sensor. The fabrication process to make the tactile sensor is developed and fabricated tactile sensor features high flexibility and can be perfectly enveloped around robotic hand finger. Calibration results show that the sensor has relatively high sensitivities for three-axis force sensing: 1.87 V/N at 0.1 ~ 0.7 N and 0.47 V/N at 0.7 ~ 3 N for z-axis normal force sensing, 1.59 V/N and 1.49 V/N at −1 ~ 1 N for x- and y-axes shear force sensing, respectively. Besides, the tactile sensor has good reproducibility and generally low cross-talk interferences between the sensing units. After being wrapped onto robotic hand finger, this sensor is utilized to measure the distributed contact forces when the robotic hand grasps different objects. The effects of grasping movements on the generated contact forces are analyzed. The obtained results demonstrate that the developed tactile sensor has great potentials for the perception of tactile information in human-robotic interactions.