Soft-bodied robots with multimodal sensing capabilities hold promise for versatile and user-friendly robotics. However, seamlessly integrating multiple sensing functionalities into soft artificial skins remains a challenge due to compatibility issues between soft materials and conventional electronics. While vision-based tactile sensing has enabled simple and effective sensor designs for robotic touch, there has been limited exploration of this technique for intrinsic multimodal sensing in large-sized soft robot bodies. To address this gap, this paper introduces a novel vision-based soft sensing technique, named ProTac, capable of operating either in tactile or proximity sensing modes. This vision-based sensing technology relies on a soft functional skin that can actively switch its optical properties between opaque and transparent states. Furthermore, the paper develops efficient learning pipelines for proximity and tactile perceptions, as well as sensing strategies enabled through the timing activation of the two sensing modes. The effectiveness of the soft sensing technology is demonstrated through a soft ProTac link, which can be integrated into newly constructed or existing commercial robot arms. Results suggest that robots integrated with the ProTac link, along with rigorous control formulation can perform safe and purposeful control actions, which enhances human-robot interaction scenarios and facilitates motion control tasks that are challenging to achieve with conventional rigid links. Supplementary video:https://youtu.be/dFgZLUpeWw4Project website:https://quan-luu.github.io/protac-website/

Tasks involving exploration and inspection of narrow environments demand a robot to have a flexible body. Such a robot is especially preferred if the integrity of its surrounding is crucial, as in endoscopy procedures. We propose the design of a small, self-propelled soft robot that can operate in a constrained environment. By periodic activation of a series of pneumatic actuators fabricated using a casting technique, sinusoidal locomotion is achieved. The wave-like locomotive strategy with an additional support mechanism enabled movement in multiple scenarios, including traveling horizontally and vertically in environments of different characteristics. Two analytical models are presented to highlight the design characteristics. The first predicts the velocity of the robot in relation to the working conditions, while the second calculates the force that the robot body exerts on its surroundings. Its mobility was tested in simple and complex routes under rigid and elastic environments. The resulting percent errors for the predictions of velocity and lateral force are 7.89% and 16.86%, respectively. In terms of performance, the robot can move horizontally in rigid tubes even if the walls are lubricated, and can achieve a peak speed of 40.11 mm/s, or 0.171 Body-Length/s (BL/s). With the addition of a tail balloon, the robot also successfully ascended a vertical tube with a maximum speed of 9.22 mm/s (or 0.039 BL/s). The presented work is expected to pave the way toward feasible robotic applications, such as pipe inspection.

There is a growing need for vertical takeoff and landing vehicles, including drones, which are safe to use and can adapt to collisions. The risks of damage by collision, to humans, obstacles in the environment, and drones themselves, are significant. This has prompted a search into nature for a highly resilient structure that can inform a design of propellers to reduce those risks and enhance safety. Inspired by the flexibility and resilience of dragonfly wings, we propose a novel design for a biomimetic drone propeller called Tombo propeller. Here, we report on the design and fabrication process of this biomimetic propeller that can accommodate collisions and recover quickly, while maintaining sufficient thrust force to hover and fly. We describe the development of an aerodynamic model and experiments conducted to investigate performance characteristics for various configurations of the propeller morphology and related properties, such as generated thrust force, thrust force deviation, collision force, recovery time, lift-to-drag ratio, and noise. Finally, we design and showcase a control strategy for a drone equipped with Tombo propellers that collides in midair with an obstacle and recovers from collision continuing flying. The results show that the maximum collision force generated by the proposed Tombo propeller is less than two-thirds that of a traditional rigid propeller, which suggests the concrete possibility to employ deformable propellers for drones flying in a cluttered environment. This research can contribute to the morphological design of flying vehicles for agile and resilient performance.