Two bioinspired mobile manipulators with rolling locomotion

This paper deals with two novel structures for mobile robots. The original inspiration of the robots comes from a salamander and a specific kind of spiders. Our robots have some especial moving capabilities causing to increase the robot maneuverability. Indeed, the capability of rolling motion is added to ordinary quadruped robots. This capability causes increment in maneuvering of the robots. Manipulators can be embedded into the robots to add the ability of transferring materials into the shell and conducting some tasks such as repairing. In this paper, after analysis of motion principles of the rolling robots, their dynamic equations are derived. Different simulations of two bioinspired mobile robots are presented in order to scrutinize various capabilities of the proposed designs. Walking capabilities of the robots and their advantages are discussed in detail. The comprehensive simulation results of the robots in various motion modes are presented. Finally the first prototype is introduced to verify the motion mechanisms

Size-dependent nonlinear secondary resonance of micro-/nano-beams made of nano-porous biomaterials including truncated cube cells

© 2018, Springer-Verlag GmbH Austria, part of Springer Nature. Porous biomaterials have been utilized in cellular structures in order to mimic the function of bone as a branch of tissue engineering approach. With the aid of nano-porous biomaterials in which the pore size is at nanoscale, the capability of biological molecular isolation becomes more efficient. In the present study, first the mechanical properties of nano-porous biomaterials are estimated on the basis of a truncated cube cell model including a refined hyperbolic shear deformation for the associated lattice structure. After that, based upon a nonlocal strain gradient beam model, the size-dependent nonlinear secondary resonance of micro-/nano-beams made of the nano-porous biomaterial is predicted corresponding to both subharmonic and superharmonic excitations. The nonclassical governing differential equation of motion is constructed via Hamilton’s principle. By employing the Galerkin technique together with the multiple-timescale method, the nonlocal strain gradient frequency response and amplitude response of the nonlinear oscillation of micro-/nano-beams made of a nano-porous biomaterial under hard excitation are achieved. It is shown that in the superharmonic case, increasing the pore size leads to an enhancement of the nonlinear hardening spring-type behavior of the jump phenomenon and the height of limit point bifurcations. In the subharmonic case, higher pore size causes an increase in the gap between two branches associated with the high-frequency and low-frequency solutions