Abstract
High-density tactile sensing has been pursued for humanoid robotic hands to obtain contact force information while the elastomer skin cover is traditionally considered to impair the force discrimination. In this work, we try to utilize the diffusion effect of the elastomer cover to identify an arbitrary contact force load just based on a sparse tactile sensor array. By numerical analysis, we proved the monotonous relation between the Pearson’s correlation coefficient and the relative distance of two single-force loads. Then, we meshed the elastomer surface and conducted the calibration load process to establish the calibration database of the sensing outputs. Afterwards, we applied the correlation method to the database and the sensing output of the unknown load to determine its location and intensity. For validation tests of the proposed method, we designed and fabricated a 3 × 3 sparse tactile sensor array with flat elastomer cover and established an automatic three-axis loading system. The validation tests were implemented including 100 random points with force intensity ranging from 0.1 to 1 N. The test results show that the method has good accuracy of detecting force load with the mean location error of 0.46 mm and the mean intensity error of 0.043 N, which meets the basic requirements of tactile sensing. Therefore, it is feasible for the sparse tactile sensor array to realize high-density load detection.
Highlights
IntroductionThe density of mechanoreceptors for tactile sensing is very high, about 17,000 units in a hand, leading to an excellent spatial resolution of about 1.6 mm for force detection [1]
Tactile sensing is indispensable for both human hand and humanoid robotic hands to grasp or manipulate objects as it offers the feedback information about the force load location and intensity.For human hand, the density of mechanoreceptors for tactile sensing is very high, about 17,000 units in a hand, leading to an excellent spatial resolution of about 1.6 mm for force detection [1]
In these tactile sensor arrays, the sensing surface is divided into scattered areas without a continuous elastomer cover and the sensor units are usually independent with each other so that each sensor unit is like a pixel of an image
Summary
The density of mechanoreceptors for tactile sensing is very high, about 17,000 units in a hand, leading to an excellent spatial resolution of about 1.6 mm for force detection [1]. It is extremely difficult for replicating such a high density of tactile sensor units in a humanoid robotic hand with existing technologies. Due to the space gap between the adjacent units, there remains blind areas for force detection, which leads to an inability of detecting an arbitrary load Most of these past studies have focused on realizing a high-density sensor
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