Tactile information is crucial for recognizing physical interactions, manipulation of an object, and motion planning for a robotic gripper; however, concurrent tactile technologies have certain limitations over directional force sensing. In particular, they are expensive, difficult to fabricate, and mostly unsuitable for underwater use. Here, we present a facile and cost-effective synthesis technique of a flexible multi-directional force sensing system, which is also favorable to be utilized in underwater environments. We made use of four flex sensors within a silicone-made hemispherical shell structure. Each sensor was placed 90${}^{°}$ apart and aligned with the curve of the hemispherical shape. If the force is applied on the top of the hemisphere, all the flex sensors would bend uniformly and yield nearly identical readings. When force is applied from a different direction, a set of flex sensors would characterize distinctive output patterns to localize the point of contact as well as the direction and magnitude of the force. The deformation of the fabricated soft sensor due to applied force was simulated numerically and compared with the experimental results. The fabricated sensor was experimentally calibrated and tested for characterization including an underwater demonstration. This study would widen the scope of identification of multi-directional force sensing, especially for underwater soft robotic applications.

Braille is one of the most popular mediums of education for the blind. However, learning braille requires trainers and a lot of practice. Additionally, different individuals have different levels of tactile sensitivity at their fingertips. The tactile components get often overlooked in most braille learning devices and related studies. Our solution is a single cell refreshable braille display with six custom-made electromechanical flapper actuators. It incorporates speech functionalities to facilitate self-learning and independent operation. The cell size can be adjusted according to the learners preference by moving the actuators. The device can provide standard braille cell dimensions and elevation as well. It is designed to help learners with different tactile perceptions improve themselves through practice and adapt to standard size braille. The operational conditions and force analysis of the braille dots were performed. Two tests were also performed with two different cell sizes to evaluate the device with several blind students. The device is very affordable and easy to maintain. It can also be used to teach braille to the sighted.

Directional force sensing is an intrinsic feature of tactile sensing. As technologies of exploratory robots evolve, with special emphasis on the emergence of soft robotics, it is crucial to equip robotic end-effectors with effective means of characterizing trends in force detection and grasping phenomena, while these trends are largely derived from networks of tactile sensors working together, individual sensors must be built to meet an intended function and maintain functionality with respect to environmental operating conditions. The harshness of underwater exploration imposes a unique set of circumstances onto the design of tactile sensors. When exposed to underwater conditions a tactile sensor must be able to withstand the effects of increased pressure paired with water intrusion while maintaining computational and mechanical integrity. Robotic systems designed for the underwater environment often become expensive and cumbersome. This paper presents the design, fabrication, and performance of a low-cost, soft-material sensor capable of multi-directional force detection. The fundamental design consists of four piezo-resistive flex elements offset at 90${}^{\circ }$ increments and encased inside of a hemispherical silicone membrane filled with a non-compressive and non-conductive fluid. The sensor is simulated numerically to characterize soft-material deformation and is experimentally interrogated with indentation equipment to investigate sensor-data patterns when subject to different contact forces. Furthermore, the sensor is subject to a cyclic loading test to analyze the effects of hysteresis in the silicone and is submerged underwater for a 7-day period to investigate any effect of water intrusion at a shallow depth. The outcome of this paper is the proposed design of a waterproofed, soft-material tactile sensor capable of directional force detection and contact force localization. The overall goal is to widen the scope of tactile sensor concepts outfitted for the underwater environment.

Perching has recently emerged as a key capability in aerial robotics, enabling substantial gains in energy efficiency and operational endurance for long-duration missions. In this work, we present a multifunctional perching mechanism capable of both branch and surface perching. For branch perching, the mechanism uses four simultaneously-actuated claws to grasp branches with diameters up to 35 mm. For surface perching, it leverages a bistable mechanism with five suction cups, allowing perching onto flat smooth surfaces with large orientation misalignment (with surface tilt angles of up to $\mathbf{80}^\circ$). The mechanism is fabricated using a combination of multimaterial 3D printing and silicone molding, resulting in a lightweight prototype with a mass of 32g. Experimental results show that the proposed design achieves $\bm{6.4\times }$ adhesion success compared to a bistable mechanism with a single suction cup. Furthermore, real-world perching experiments onto cars and tree branches demonstrate the effectiveness of the mechanism in different environments, highlighting its potential for energy-efficient and adaptable aerial robotic operations.

The present study explores the effect of using two porous deflectors on the performance of the Savonius wind turbine compared to only one porous deflector. The numerical simulation is performed to solve the unsteady Navier-Stokes equations using the SST k-