Magnetic adsorption mechanisms are widely used for wall-climbing robots to manipulate a locomotive on the surface of a magnetic conducting metal. However, the reported magnetic adsorption mechanisms are subject to the problems such as the lack of adsorption capability, the weakness of kinematic performance, and the overwhelming detaching force. To solve the problems, a novel style of a permanent-magnetic adsorption mechanism using an electromagnetic method and internal force compensation principle is detailed in this work. Specifically, a permanent magnet, an electromagnet, and a nonlinear spring are configurated to achieve a reliable adsorption function by using the minimal detaching force. Following that, the results obtained from both the finite element analysis and the experiments carried out by using a prototype demonstrated its effectiveness. It does not only have a rapid and controllable adsorption-detachment capacity in reference to the magnetic conducting surface but also has low power consumption, large adsorption force, and reliable and safe performance.

Frogs are vertebrate amphibians with both efficient swimming and jumping abilities due to their well-developed hind legs. They can jump over obstacles that are many or even tens of times their size on land. However, most of the current jumping mechanisms of biomimetic robotic frogs use simple four-bar linkage mechanisms, which has an unsatisfactory biomimetic effect on the appearance and movement characteristics of frogs. At the same time, multi-joint jumping robots with biomimetic characteristics are subject to high drive power requirements for jumping action. In this paper, a novel jumping mechanism of a biomimetic robotic frog is proposed. Firstly, the structural design of the forelimb and hindlimb of the frog is given, and the hindlimb of the robotic frog is optimized based on the design of a single-degree-of-freedom six-bar linkage. A simplified model is established to simulate the jumping motion. Secondly, a spring energy storage and trigger mechanism is designed, including incomplete gear, one-way bearing, torsion spring, and so on, to realize the complete jumping function of the robot, that is, elastic energy storage and regulation, elastic energy release, and rapid leg retraction. Thirdly, the experimental prototype of the biomimetic robotic frog is fabricated. Finally, the rationality and feasibility of the jumping mechanism are verified by a jumping experiment. This work provides a technical and theoretical basis for the design and development of a high-performance amphibious biomimetic robotic frog.

Pneumatic Muscle Actuator (PMA) has a broad application prospect in soft robotics. However, PMA has highly nonlinear and hysteretic properties among force, displacement, and pressure, which lead to difficulty in accurate position control. A phenomenological model is developed to portray the hysteretic behavior of PMA. This phenomenological model consists of linear component and hysteretic component force. The latter component is described by Duhem model. An experimental apparatus is built up and sets of experimental data are acquired. Based on the experimental data, parameters of the model are identified. Validation of the model is performed. Then a novel cascade position PID controller is devised for a 1-DOF manipulator actuated by PMA. The outer loop of the controller is to cope with position control whilst the inner loop deals with pressure dynamics within PMA. To enhance the adaptability of the PID algorithm to the high nonlinearities of the manipulator, PID parameters are tuned online using RBF Neural Network. Experiments are performed and comparison between position response of RBF Neural Network based PID controller and that of classic PID controller demonstrates the effectiveness of the novel adaptive controller on the manipulator.

Under self-assembly, a novel polydentate benzimidazole ligand 2-(quinoline-2-yl)-benzimidazole (2-QLBM) and two In(III) compounds, [In(2-Hqlca)₂Cl₃·3H₂O] (1) and {[In(2-QLBM)(2-qlca)Cl₂]₂·CH₃CN·2H₂O} (2) (2-Hqlca = 2-quinolinecarboxylic acid) have been synthesized and characterized. Both the In(III) compounds are driven by noncovalent interactions to assemble into supramolecular metal–organic frameworks (MOFs). Considering 2-QLBM and 2-Hqlc ligands with different geometrical structures, compound 1 possesses a (6⁶)-dia network with a channel diameter of about 1.856 Å, and compound 2 displays a (3,4)-connected topology network with the Schläfli symbol of (6³)(6⁵·8), whose channel diameter is about 3.683 Å. Owing to large voids in the framework, 2 can serve as a host for reversible encapsulation of iodine corresponding to the 1.52 molecules of iodine per formula unit with a fast response and high sensitivity. Upon irradiation with UV light, the two compounds display tunable fluorescence emission from blue to yellow by varying the temperature. Moreover, the absorption spectra demonstrate that the band gaps of compounds 1 and 2 are 3.71 and 3.58 eV, respectively. When adsorbing iodine into the framework, the host structure of 2 is relatively perturbed by the presence of guests and exerts a remarkable influence on the band size and gap state.