Tactile sensors are the last frontier to robots that can handle everyday objects and interact with humans through contact. To be effective, such sensors have to sense the geometry of touched surfaces and objects, as well as any other relevant information for their tasks, such as forces, vibrations, and temperature, that allow them to safely and securely interact within an environment. Given the capability of humans to easily capture and interpret tactile data, one promising direction in order to produce enhanced robotic tactile sensors is to explore and imitate human tactile sensing capabilities. In this context, this paper presents design and hardware implementation issues related to the construction a novel bio-inspired tactile sensing module. Drawing inspiration from the type, functionality, and organization of cutaneous tactile elements, the proposed solution comprises two shallow sensors, namely, a 32-taxel-tactile array and a nine DOF magnetic, angular rate, and gravity sensor, a flexible compliant structure, and a deep pressure sensor placed in a structure similar to human skin. The module's compliant structure and sensor placement provides useful data to overcome the problem of estimating nonnormal forces accommodating sensing modalities essential for acquiring tactile images, and classifying surfaces by vibrations and accelerations. Issues related to the module calibration, its sensing capabilities and possible real world applications are also presented.

Social media platforms have become the most prominent medium for spreading hate speech, primarily through hateful textual content. An extensive dataset containing emoticons, emojis, hashtags, slang, and contractions is required to detect hate speech on social media based on current trends. Therefore, our dataset is curated from various sources like Kaggle, GitHub, and other websites. This dataset contains hate speech sentences in English and is confined into two classes, one representing hateful content and the other representing non-hateful content. It has 451,709 sentences in total. 371,452 of these are hate speech, and 80,250 are non-hate speech. An augmented balanced dataset with 726,120 samples is also generated to create a custom vocabulary of 145,046 words. The total number of contractions considered in the dataset is 6403. The total number of bad words usually used in hateful content is 377. The text in each sentence of the final dataset, which is utilized for training and cross-validation, is limited to 180 words. The generated contractions dataset can be used for any projects in the area of NLP for data preprocessing. The augmented dataset can help to reduce the number of out-of-vocabulary words, and the hate speech dataset can be used as a classifier to detect hate or no hate on social media platforms.

Robots are expected to recognize the properties of objects in order to handle them safely and efficiently in a variety of applications, such as health and elder care, manufacturing, or high-risk environments. This paper explores the issue of surface characterization by monitoring the signals acquired by a novel bio-inspired tactile probe in contact with ridged surfaces. The tactile module comprises a nine Degree of Freedom Microelectromechanical Magnetic, Angular Rate, and Gravity system (9-DOF MEMS MARG) and a deep MEMS pressure sensor embedded in a compliant structure that mimics the function and the organization of mechanoreceptors in human skin as well as the hardness of the human skin. When the modules tip slides over a surface, the MARG unit vibrates and the deep pressure sensor captures the overall normal force exerted. The module is evaluated in two experiments. The first experiment compares the frequency content of the data collected in two setups: one when the module is mounted over a linear motion carriage that slides four grating patterns at constant velocities; the second when the module is carried by a robotic finger in contact with the same grating patterns while performing a sliding motion, similar to the exploratory motion employed by humans to detect object roughness. As expected, in the linear setup, the magnitude spectrum of the sensors’ output shows that the module can detect the applied stimuli with frequencies ranging from 3.66 Hz to 11.54 Hz with an overall maximum error of ±0.1 Hz. The second experiment shows how localized features extracted from the data collected by the robotic finger setup over seven synthetic shapes can be used to classify them. The classification method consists on applying multiscale principal components analysis prior to the classification with a multilayer neural network. Achieved accuracies from 85.1% to 98.9% for the various sensor types demonstrate the usefulness of traditional MEMS as tactile sensors embedded into flexible substrates.

Underactuated hands are useful tools for robotic in-hand manipulation tasks due to their capability to seamlessly adapt to unknown objects. To enable robots using such hands to achieve and maintain stable grasping conditions even under external disturbances while keeping track of an in-hand object’s state requires learning object-tactile sensing data relationships. The human somatosensory system combines visual and tactile sensing information in their “What and Where” subsystem to achieve high levels of manipulation skills. The present paper proposes an approach for estimating the pose of in-hand objects combining tactile sensing data and visual frames of reference like the human “What and Where” subsystem. The system proposed here uses machine learning methods to estimate the orientation of in-hand objects from the data gathered by tactile sensors mounted on the phalanges of underactuated fingers. While tactile sensing provides local information about objects during in-hand manipulation, a vision system generates egocentric and allocentric frames of reference. A dual fuzzy logic controller was developed to achieve and sustain stable grasping conditions autonomously while forces were applied to in-hand objects to expose the system to different object configurations. Two sets of experiments were used to explore the system capabilities. On the first set, external forces changed the orientation of objects while the fuzzy controller kept objects in-hand for tactile and visual data collection for five machine learning estimators. Among these estimators, the ridge regressor achieved an average mean squared error of ${0.077}^{\circ }$ . On the second set of experiments, one of the underactuated fingers performed open-loop object rotations and data recorded were supplied to the same set of estimators. In this scenario, the Multilayer perceptron (MLP) neural network achieved the lowest mean squared error of ${0.067}^{\circ }$ .

A human-like touch and feel ability is still a major challenge yet to be solved in order to accelerate robot's transition from performing routine, preplanned, tasks in structured industrial environments to creatively performing tasks in unstructured environments such as nuclear stations, war zones, underwater, outer space, healthand elder-care, or telemedicine. Due to those unsolved challenges encountered in the development of a truly human-like touch sensing and perception capability for humanoid robot hands, considerable effort is still required before achieving the point of replicating the human hand's abilities by a multi-finger robot hand able to efficiently carry on dexterous robotic manipulation operations. All these challenges provide a strong incentive for using the bio-inspired approaches to develop efficient static and dynamic touch sensing technologies for the new generation of humanoid robots.