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This paper presents designing and prototyping of an inflatable soft crawling robot equipped with nondestructive testing (NDT) sensing capability for inspection and diagnosis of potential mechanical faults in overhead power cables. The soft robot is comprised of two gripping modules with radial expansion/contraction, one at the proximal and the other one at the distal end, and a longitudinal contractile-expandable driving module in-between for providing a bi-directional crawling movement. The robot and its soft actuators are made of fabrics and can be wrapped around the power line cables for navigation. The main novelty of the current robotic inspection platform is to integrate the mobility component with an NDT sensing system. Conceptual designs and CAD models of the robot parts, textile-based inflatable structures, and the pneumatic driving mechanisms were developed. The mechanical parts were fabricated using advanced and conventional manufacturing techniques. An Arduino-based electropneumatic control board was developed including proper pneumatic circuits, pumps, sensors, and batteries. The fabricated parts were assembled to create the initial prototype of the soft robot. Control algorithms were developed for the operation of the robot. The prototyped mechanism was tested in a laboratory setting while the collected data were used for modifying the designs, and controlling software and hardware. The feasibility of the proposed robot for cable crawling and multimodal NDT sensing was successfully demonstrated.

The aye-aye (Daubentonia madagascariensis) is best known for its unique acoustic-based foraging behavior called 'tap-scanning' or 'percussive foraging'. The tap-scanning is a unique behavior allowing aye-aye to locate small cavities beneath tree bark and extract wood-boring larvae from it. The tap-scanning requires the animal auditory system to have exceptional acoustic near-field sensitivity. This paper has experimentally investigated the effects of external pinna in the acoustic sensing and detection capabilities of aye-ayes. To experimentally evaluate the effects of external ear (pinna) of the aye-aye, the tap-scanning process was simulated using a robotic arm. A pinna was 3D printed using a CT scan obtained from a carcass. The pinna's effect on the acoustic near-field has been evaluated in time and frequency domains for simulated tap-scanning with the pinna in upright and cupped positions. This idea originates from behavioral observations of the aye-aye using its ears in this way. The results suggest that the aye-aye can substantially enhance its acoustic near-field sensitivity through a cupped conformation during tap-scanning. Three phenomena contribute to this substantial enhancement of the acoustic near-field: (i) a considerable increase in the signal-to-noise ratio, (ii) the creation of a focal area and potentially a focal point to increase the spatial resolution, and (iii) an increase in the receiver peak frequency by changing near-field beam pattern for higher frequencies that can result in greater sensitivity due to a smaller wavelength.

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