Soft robotics最新文献

Autonomous navigation of cyborg insects in complex environments remains a challenging issue. Cyborg insects, which combine biological organisms with electronic components, offer a unique approach to tackle such challenges. This study presents a biohybrid behavior-based navigation (BIOBBN) system that enables cyborg cockroaches to navigate complex environments autonomously. Two navigation algorithms were developed: reach-avoid navigation for less complex environments and adaptive reach-avoid navigation for more challenging scenarios. This algorithm, especially the second one, leveraged the cockroaches' natural behaviors, such as wall-following and climbing, to navigate around and over obstacles. Experiments in simulated environments, including sand and rock-covered surfaces, demonstrate the effectiveness of the BIOBBN system in enabling cyborg cockroaches to navigate and reach target locations. The denser second scenario required more time due to increased obstacle avoidance and natural climbing behavior. Overall performance was promising, highlighting the potential of biohybrid navigation for autonomous cyborg insects in navigating complex environments.

Small-scale soft robots, despite their potential for adaptability in unknown environments, often encounter performance constraints due to inherent limitations within soft actuators and compact bodies. To address this problem, we proposed a fast-moving soft robot driven by electroactive materials. The robot combines the advantages of dielectric elastomer actuators (DEAs) and shape memory alloy (SMA) spring actuators, enabling its high-performance multi-modal locomotion in a small and lightweight design. Theoretical models were constructed for both DEAs and SMA spring actuators to analyze the performance of the designed robot. The robot's design parameters were optimized based on these models to improve its running and jumping performance. The designed robot has a size of 40 × 45 × 25 mm and a weight of 3.5 g. The robot can achieve a running speed of 91 mm/s, ascend a 9° slope, and execute turning motions via an asymmetrical actuation of SMA spring actuators. The robot also demonstrates high-performance jumping motions with a maximum jumping height of 80 mm and the ability to jump over a 40 mm high obstacle. This work introduces a novel approach to designing small-scale soft terrestrial robots, enhancing their agility and mobility in obstacle-laden environments.

The high degree of freedom (DoF) shape morphing widely exists in biology for mimicry, camouflage, and locomotion. Currently, a lot of bionic soft/flexible actuators and robots with shape-morphing functions have been developed to realize conformity, grasp, and movement. Among these solutions, two-dimensional responsive materials and structures that can shape morph into different three-dimensional configurations are valuable for creating reversible high DoF shape morphing. However, most existing methods are predetermined through the fabrication process and cannot reprogram their shape, facing limitations on multifunction. Besides, the achievable geometries are very limited due to the device's low integrated level of actuator elements. Here, we develop a polyvinylidene fluoride flexible piezoelectric actuator array based on a row/column addressing (RCA) scheme for reprogrammable high DoF shape morphing and locomotion. The specially designed row/column electrodes form a 6 × 6 array, which contains 36 actuator elements. By developing a high-voltage RCA control system, we can individually control all the elements in the array, leading to a highly reprogrammable array with various sophisticated high DoF shape morphing. We also demonstrate that the array is capable of propelling a robotic fish with various locomotions. This research provides a new method and approach for biomimetic robotics with better mimicry, aero/hydrodynamic efficiency, and maneuverability, as well as haptic display and object manipulation.

The myocardial contracting ratio is approximately 20%, whereas ejection fraction exceeds 60%. Understanding the structure and kinetic mechanisms of the heart that enable this high ejection fraction is crucial in both basic and clinical medicine. However, these mechanisms remain incompletely elucidated. The authors have developed a functional model based on the unique myocardial band theory, which posits that the ventricle is formed by a single myocardial band winding into a spiral. According to this theory, a muscle band, which incorporated thin McKibben artificial muscles embedded within a soft elastomer, was formed, and it was subsequently rolled to replicate the ventricle's structure. Thin McKibben muscles are well-suited for mimicking cardiac muscles due to their longitudinal contraction, radial expansion, and ability to operate in a curved position. In general, animal hearts exhibit approximately 20% myocardial contracting ratio, a 1.2-fold change in myocardial band thickness, and an ejection fraction in the range 50-70%. In comparison, soft robotic hearts demonstrated values of 17.3%, a 1.28-fold thickness change, and a 47.8% ejection fraction, respectively, which closely approximated those of real hearts. Water ejection experiments conducted using a soft robotic heart revealed that the maximum pressure during contraction reached 200 mmHg, generating a pressure-volume loop similar to that observed in the human heart. Thus, soft robotic hearts hold the potential for a wide range of clinical applications, including the elucidation of heart failure pathophysiology and the development of surgical treatments.

In atypical industrial settings, soft grippers needed to adjust to different object shapes. Existing grabbers typically accommodated only single-curvature, fixed-stiffness objects, restricting their stability and usability. This study presents a design for a finger featuring multi-curvature, incorporating a wedge actuator alongside two variable stiffness units (VSUs) inspired by snake scales. By adjusting the high stiffness and low stiffness states of the variable stiffness element, the local structural stiffness of the finger was changed, thereby granting the gripper capabilities in bending shape control and variable stiffness. A finite element model of the wedge actuator was developed, and the influence of several parameters, including top wall thickness, side wall thickness, transition layer thickness, and sidewall height on bending angle and tip output force was analyzed through an orthogonal experiment. Furthermore, the relationship between the longitudinal length of the wedge actuator and both the bending angle and the tip output force was studied. Via explicit dynamic analysis, the stiffness variation of the VSU under operational vacuum pressure was predicted and subsequently validated against experimental data, confirming the reliability of the model. The effectiveness of finger shape control and stiffness adjustment was evaluated through experiments. Ultimately, a two-finger gripper was constructed to carry out the grasping experiments. The results showed that the gripper is capable of generating various clamping curvatures, enabling it to conform closely to the objects it grips and significantly broaden its clamping range.

Soft optical sensors, characterized by excellent stability, strong anti-interference ability, and rapid response, are particularly suitable for exploring unknown environments. However, the low sensitivity and large size of optical tactile sensors have limited their widespread application. This study presents an ultrasensitive, highly linear, and highly robust three-dimensional (3D) tactile sensor based on a Foldable Optical Circuit Embedded in Rigid-Soft-coupled (FOCERS) structure. This sensor exhibits a high sensitivity of 1228.7 kPa^-1 under normal pressure of 5 kPa, a super high sensitivity of 7399.5 kPa^-1 under a sheer pressure of 1.5 kPa, and a fast response time of 5 ms. Under normal pressure conditions, the sensors exhibited high linearity performance across the entire sensing range, with linearity reaching up to 95.3%. The rigid-soft-coupled structure enhances the robustness and overload resistance of the sensor (withstanding 50 times the sensing range). Demonstrations show that the FOCERS structure can detect minute pressure variations (induced by sesame seeds) and withstand extreme pressures (such as being run over by a car). Furthermore, we designed a joystick based on FOCERS for force detection in human-machine interactions. This study provides a new structure for optical sensors to increase both sensitivity and robustness, and also provides a convenient way to fabricate 3D tactile sensors.

The inherent challenges of robotic underwater exploration, such as hydrodynamic effects, the complexity of dynamic coupling, and the necessity for sensitive interaction with marine life, call for the adoption of soft robotic approaches in marine exploration. To address this, we present a novel prototype, ZodiAq, a soft underwater drone inspired by prokaryotic bacterial flagella. ZodiAq's unique dodecahedral structure, equipped with 12 flagella-like arms, ensures design redundancy and compliance, ideal for navigating complex underwater terrains. The prototype features a central unit based on a Raspberry Pi, connected to a sensory system for inertial, depth, and vision detection, and an acoustic modem for communication. Combined with the implemented control law, it renders ZodiAq an intelligent system. This article details the design and fabrication process of ZodiAq, highlighting design choices and prototype capabilities. Based on the strain-based modeling of Cosserat rods, we have developed a digital twin of the prototype within a simulation toolbox to simplify analysis and control. To optimize its operation in dynamic aquatic conditions, a simplified model-based controller has been developed and implemented, facilitating intelligent and adaptive movement in the hydrodynamic environment. Extensive experimental demonstrations highlight the drone's potential, showcasing its design redundancy, embodied intelligence, crawling gait, and practical applications in diverse underwater settings. This research contributes significantly to the field of underwater soft robotics, offering a promising new avenue for safe, efficient, and environmentally conscious underwater exploration.

The ability to achieve controllable multimodal locomotion on complex terrains is crucial for the practical applications of small-scale legged robots. In this study, a novel magnetically actuated soft quadrupedal terrestrial millirobot was designed. Inspired by biological terrestrial locomotion modes, three distinct locomotion modes-quadrupedal bounding, quadrupedal pacing, and bipedal walking-were realized through a combination of various postures under a uniform external magnetic field and asymmetrical friction effects induced by magnetic torque. The characteristics of these modes were examined and compared, including the effects of magnetic field strength, swing angle, and surface roughness on stride length. Furthermore, the line-of-sight control method was implemented in path-tracking experiments, enabling closed-loop control on complex paths and improving tracking accuracy. This research holds significant potential for applying magnetically controlled small-scale robots in the bioengineering and industrial micromanipulation fields.

Based on the analysis of the structures of robots and electronics developed so far, it should be noted that a majority of them need a reservoir for electrical energy storage. Unfortunately, most off-the-shelf devices commercially available nowadays are based on rigid parts that heavily limit the possibilities of incorporating such products into soft robots and wearable electronics. To address these issues, a new type of flexible structure for electrical energy storage, which consists of small battery cells connected by liquid metal paths, was proposed. It can achieve a low value of Young's modulus (about 0.13 MPa) while maintaining electrochemical stability for large stretches (max. capacity reduction-2%). We proposed an individual layer structure as well as a sandwich structure with a granular core, which by way of granular jamming phenomena can change the stiffness (almost 300%). This article describes the concept and working principle of the proposed flexible electrical energy storage structure, followed by the mechanical and electrical characterization, electrochemical impedance spectroscopy, and galvanostatic battery cell cycling. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to characterize the electrodes. The article also includes numerical simulations and potential applications of the studied structure.

Colorectal cancer stands as one of the most prevalent cancers globally, representing 9.8% of total cases and contributing to 9.2% of mortalities annually. Robotic "front-wheel" navigating colonoscopes mitigate aggressive stretching against the long and tortuous colonic wall, alleviating associated discomfort and pain typically experienced by patients inspected by conventional "back-wheel" navigating colonoscopes. The anchoring unit of most "front-wheel" navigating colonoscopes plays a crucial role in ensuring effective locomotion by preventing slipping during elongation/contraction of the central actuation part. The soft balloon anchoring actuator emerges as a promising solution due to its high compliance. This study introduces a dumbbell-shaped balloon anchoring actuator (DBAA) integrating an "inflation and suction" mechanism to address the inherent conflict between achieving sufficient anchoring force and minimizing expansion and potential trauma of the colonic wall, commonly encountered in current balloon anchoring actuators. Analytical modeling of DBAA and soft external lumen, encompassing geometric deformation and anchoring force, were proposed to characterize the actuator and provide guidelines for designing and controlling DBAA in further applications, enabling autonomous anchoring within different diameter lumens and achieving the expected anchoring force. A comprehensive set of validation experiments was conducted, and the outcomes revealed high consistency with analytical predictions, confirming the effectiveness of the proposed analytical modeling approach. Furthermore, the results demonstrated a significant enhancement in anchoring force with the proposed actuator and corresponding mechanism while concurrently maintaining low-lumen expansion. For instance, in a lumen sample with ${\text{R}}_{in}=15mm,\hspace{0.17em}{\text{Λ}}_2=105\%,$ the anchoring force reaches 14.5 N with 50 kPa negative pressure, which is 12.4 times of the force (1.17 N) observed without applying negative pressure.