This paper introduces an approach to fabricating lightweight, untethered soft robots capable of diverse biomimetic locomotion. Untethering soft robotics from electrical or pneumatic power remains one of the prominent challenges within the field. The development of functional untethered soft robotic systems hinges heavily on mitigating their weight; however, the conventional weight of pneumatic network actuators (pneu-nets) in soft robots has hindered untethered operations. To address this challenge, we developed film-balloon (FiBa) modules that drastically reduced the weight of soft actuators. FiBa modules combine transversely curved polymer thin films and three-dimensionally printed pneumatic balloons to achieve varied locomotion modes. These lightweight FiBa modules serve as building blocks to create untethered soft robots mimicking natural movement strategies. These modules substantially reduce overall robot weight, allowing the integration of components such as pumps, valves, batteries, and control boards, thereby enabling untethered operation. FiBa modules integrated with electronic components demonstrated four bioinspired modes of locomotion, including turtle-inspired crawling, inchworm-inspired climbing, bat-inspired perching, and ladybug-inspired flying. Overall, our study offers an alternative tool for designing and customizing lightweight, untethered soft robots with advanced functionalities. The reduction of the weight of soft robots enabled by our approach opens doors to a wide range of applications, including disaster relief, space exploration, remote sensing, and search and rescue operations, where lightweight, untethered soft robotic systems are essential.

The monocopter is a type of micro aerial vehicle largely inspired from the flight of botanical samaras (Acer palmatum). A large section of its fuselage forms the single wing where all its useful aerodynamic forces are generated, making it achieve a highly efficient mode of flight. However, compared to a multi-rotor of similar weight, monocopters can be large and cumbersome for transport, mainly due to their large and rigid wing structure. In this work, a monocopter with a foldable, semi-rigid wing is proposed and its resulting flight performance is studied. The wing is non-rigid when not in flight and relies on centrifugal forces to become straightened during flight. The wing construction uses a special technique for its lightweight and semi-rigid design, and together with a purpose-designed autopilot board, the entire craft can be folded into a compact pocketable form factor, decreasing its footprint by 69%. Furthermore, the proposed craft accomplishes a controllable flight in 5 degrees of freedom by using only one thrust unit. It achieves altitude control by regulating the force generated from the thrust unit throughout multiple rotations. Lateral control is achieved by pulsing the thrust unit at specific instances during each cycle of rotation. A closed-loop feedback control is achieved using a motion-captured camera system, where a hybrid proportional stabilizer controller and proportional-integral position controller are applied. Waypoint tracking, trajectory tracking and flight time tests were performed and analyzed. Overall, the vehicle weighs 69 g, achieves a maximum lateral speed of about 2.37 m s⁻¹, an average power draw of 9.78 W and a flight time of 16 min with its semi-rigid wing.

Inspection of deep tunnel networks is extremely challenging due to their inaccessibility, and them being an unknown and potentially hazardous environment. Unmanned aerial vehicles (UAVs) provide a viable alternative for access, and are unaffected by debris or sewer flow. However, commercial UAVs are designed for high altitude aerial imagery and are not appropriate for short-range detailed imaging of tunnel surfaces. In addition, autonomous flight is usually achieved using GPS, which is not available underground. This paper presents the design and development of a smart UAV platform, Surveyor with Intelligent Rotating Lens (SWIRL), customized for autonomous operation in tunnels. It can capture high resolution images for subsequent image processing, and defect detection and classification. An innovative rotating system enables undistorted imaging of the tunnel's inner circumference surface using a single camera. The proposed location method using limited data resulted in substantial unit weight and power consumption reductions, compared to existing systems, making more than 35 minutes of autonomous flight possible.

Large scale aerial deployment of miniature sensors in tough environmental conditions requires a deployment device that is lightweight, robust, and steerable. We present a novel samara-inspired autorotating craft that is capable of two flight modes (autorotating mode and diving mode) with an average glide angle of 28.9 $^{\circ }$ (1.81 m lateral distance per 1 m loss of altitude) in the former mode. The bidirectional transition between the two modes and directional control is achieved by using only a single actuator. Also, in order to minimize its glide angle, a design optimization methodology is presented for our prototype, diving samara autorotating wing, along with a new cyclic control strategy for directional control of autorotating descent. The dynamic model, simulated in a six degrees-of-freedom environment using the blade element theory, is integrated with genetic algorithm to derive parameters for the wing geometry, flap angle for autorotation, and the proposed cyclic control. The physical prototype autorotates at a descent velocity of 1.43 m/s and rotation speed 4.17 Hz, and is able to transit to diving mode in an average duration of 272 ms to increase its descent velocity by at least 17.6 times. At any point during the dive, it is able to transit back into autorotation in an average duration of 327 ms. Semioutdoor experiments were used to investigate the bidirectional transitions and verify the glide angle (28.9 $^{\circ }$ ), which is much improved from the previous prototype (SAW+, 58.4 $^{\circ }$ ). Lastly, as a demonstration of a real-life deployment scenario and environmental conditions, the prototypes were dropped from a fixed-wing unmanned aerial vehicle at a suburban test site.

To deliver lightweight sensor payloads to disaster-struck areas by means of an aerial deployment, a novel bio-inspired method capitalizing on autorotation to slow down vertical descent rate is proposed. This concept is illustrated using the Samara Autorotating Wing (SAW) platform which features a unique collaborative mode where multiple individual units are attached mechanically together to form a collective rotor hub for increased controllability. This rotor is designed with a simple de-centralized separation mechanism to detach into singular units during flight upon command, catering to different mission profiles. The dynamic models for singular state and collaborative rotor hub state were developed, and freeflight simulations were conducted in different modes including the separation stage and control performance for both states was analyzed. Experiments were set up for increased motioncapture region and free-flight drop tests and separation flights were carried out to verify the simulations. Finally, using a multirotor as an aerial launch platform, control performance for the single-winged state was evaluated in real-world conditions.

Unmanned Aerial Vehicles (UAV) have gained massive interest due to their wide range of applications. In this work, we focus on the design of compact rotation speed sensors (RSS) and air flow sensors (AFS) that can be integrated into nature-inspired monocopters UAVs which generate lift by spinning at high frequencies. Combining barometric sensors and sensing elements embedded into soft elastomers, compact, accurate, reliable, and low power sensors that can measure rotation and air flow speed can be fabricated. Through numerical analysis and design, it is possible to customize the sensor to measure rotation speed or air flow at specific operating ranges. The AFS was experimentally capable of measuring airflow speeds up to 60m/s, a range in which anemometers commonly saturate at. Consequently, the developed RSS can measure frequencies up to 10Hz accurately, whereas inertia measurement units (IMUs) saturate at 5.5Hz. Finally, the RSS sensors were mounted on a monocopter prototype, to evaluate and assess the sensors under actual flying conditions, where the UAV’s movements were tracked by an onboard flight controller’s (Pixracer) in-built IMU as well as a high accuracy external optical motion capture system (OptiTrack). The RSS proved to be a reliable alternative to IMUs for navigation control of Monocopters.