Inspired by natural earthworms’ locomotion mechanism, this paper investigates how the earthworm’s muscle works and presents the approach to mimic segmental muscle by employing rigid elements-based morphing structures. Specifically, the proposed earthworm-like robot employs a class of 2D rigid elements and their array to achieve programable bidirectional 3D deformation, making the formed mechanism precisely controllable and work effectively, thus facilitating the robot’s peristaltic locomotion more efficient. To comprehensively investigate the morphing structure and its formed earthworm-like robot, the kinematics, mechanics, deformation-dependent locomotion framework with its adapted model, as well as the factors that affect the optimal velocity are developed and presented. Extensive simulations and experiments on the proposed robot are performed. The results verify the effectiveness of the morphing mechanism and it enabled earthworm-like robot and the consistency between the proposed locomotion model and the practical tests. The results also prove that regardless of the condition of the contact surface, the optimal phase shift angle can be achieved when each segment approximately contracts and relaxes once in one wavelength period. Our developed prototype achieves a speed of multiple body lengths per minute, which is very competitive compared with most developed earthworm-like robots.

This paper focuses on designing, kinematically and dynamically characterizing a novel deformable quad-rotor that is based on the scissor-like foldable mechanisms. Inspired by morphological adaptation of birds during flight, the quad-rotor allows that its volume can be varied to dynamically adapt complex environments and spaces. The advantages of such mechanism are twofold following the scenario, that is, the quad-rotor can stably fly with a big volume/size and can also switch to a smaller volume for a swift flight in response to the changes of the environments and spaces. It therefore is capable of efficiently avoiding obstacles, stably passing through narrow spaces, and resisting certain-extent wind effects. To generate the controllable deformation, the actuated angulated scissor elements in the structure play an important role. In this paper, the scissor element design, its actuation mechanism, and volume deformation of the new quad-rotor are presented in detail. Simulations and experiments are then conducted to validate the controlled deformation as well as to investigate the deformation elicited effects to the activated quad-rotor airframe and its aerodynamics. The results demonstrate the effectiveness of the proposed deformable quad-rotor, and prove that it enables excellent volume deformation performance, good flight adaptation, as well as minimal aerodynamics influences during deforming.

Microforce sensors capable of measuring multiple degrees of freedom are in wide demand in miniature medical applications, but they are currently not available on a large scale due to high cost, fragility, and limited resolution. Therefore, this paper presents a low-cost three-dimensional (3-D) microforce sensor based on hybrid carbon/polymer-based soft piezoresistive films (HCP) with high sensitivity and robustness, as well as low thermal drift and hysteresis. Besides, due to the difficulty of constructing an accurate model to calibrate the flexible material-based sensor, this paper employs data-based calibration methods to achieve fast calibration. Additionally, the developed prototype is continuously and dynamically tested from hundreds of micro-newtons to dozens of millinewtons. The developed sensor is experimentally proven to be highly sensitive, durable, low-cost, self-decoupling, and impact-resistant for potential miniature biomedical applications.

Inspired by the inchworm locomotion mechanism, this paper presents our recently developed self-deformable capsule-like robot. The robot has the actuated deformation capability that relies on a novel rigid elements-based morphing structure (REMS) and its soft actuation mechanisms. When the robot deforms, it generates the crawling locomotion behavior and thus friction waves between the robot and contact surface to facilitate the inchworm-like crawling movement. The paper starts reviewing the deformable properties of natural biological entities like capsules, presents state of the art of the current capsule-like robots, and details the bio-inspired design of the self-deformable capsule-like robot by describing the model of robot kinematics and its locomotion mechanism. Both simulation and experimental results validate the excellent performance of this capsule-like robot. The developed self-deformable capsule-like robot has the advantage of crawling on varied surfaces and it also has the capabilities to crawl in a variety of narrow pipes based on the deformation elicited locomotion nature of the robot.

Existing studies rarely investigate the dynamic morphology factor on motion planning and control, which is crucial for morphing quadrotors to achieve autonomous flight. Therefore, this paper studies the collaborative optimization of trajectory generation and flight control for the morphing quadrotor with real-time adjustable arms. In the motion planning layer, an objective function that combines position and morphology is constructed by embedding variable arm length as a decision variable into the conventional minimum snap trajectory generation framework. The generated trajectory not only satisfies the speed and acceleration constraints, but also smoothly passes through the narrow spaces that are difficult for traditional quadrotors to traverse. In the control layer, a constrained augmented model predictive control based on the dynamics of the morphing quadrotors is proposed to follow the generated trajectory with an embedded integrator, which is added by exploiting the differential flat variables to improve the tracking performance. In the numerical studies, a scenario with a corridor was considered to demonstrate the effectiveness of the proposed control strategy to achieve optimal trajectory under multiple constraints.