Magnetically Deployable Robots Using Layered Lamina Emergent Mechanism

The steady rise of deployable structures and mechanisms based on kirigami and origami principles has brought about design innovations that yield flexible and lightweight robots. These robots are designed based on desirable locomotion mechanisms and often incorporate additional materials to support their flexible structure to enable load-bearing applications and considerable efficient movement. One tetherless way to actuate these robots is via the use of magnets. This paper incorporates magnetic actuation and kirigami structures based on the lamina emergent mechanism (LEM). Three designs of magnetic-actuated LEMs (triangular prism, single LEM (SLEM), alternating mirror dual LEM (AMDLEM)) are proposed, and small permanent magnets are attached to the structures’ flaps or legs that rotate in response to an Actuating Permanent Magnet (APM) to yield stick-slip locomotion, enabling the robots to waddle and crawl on a frictional surface. For preliminary characterization, we actuate the three designs at a frequency of 0.6 Hz. We observed the triangular prism, SLEM, and AMDLEM prototypes to achieve horizontal speeds of 4.3 mm/s, 10.7 mm/s, and 12.5 mm/s on flat surfaces, respectively. We further explore how changing different parameters (actuation frequency, friction, leg length, stiffness, compressibility) affects the locomotion of the different mechanisms.

Dynamics of a simplified nonlinear model offering insights into the hammering type brake squeal initiation process

This article develops a simplified mechanical system model that offers insights into the hammering type brake squeal initiation process while overcoming a void in the literature. The proposed formulation derives a nonlinear two-degree-of-freedom model where a mass is in contact with a rigid frictional surface that moves with constant velocity. The kinematic nonlinearities arise from an arrangement of springs that support the mass, as well as from contact loss between the mass and frictional surface. First, the nonlinear governing equations are numerically solved for several normal force vector arrangements, and a wide range of dynamic responses are observed. Results show that some assumptions made in prior articles are not valid. Second, the nonlinear governing equations are linearized, and the existence of quasistatic sliding motion is sought for selected inclined spring arrangements. Third, the dynamic stability of the linearized system is examined and compared with the results of a nonlinear model. The coupled modes are found even though some contradictions between the model assumptions and linearized system solutions are observed. Finally, the nonlinear frequency responses are calculated using the multi-term harmonic balance method although only the contact loss nonlinearity is retained. Shifts in the resonant frequencies during the motion of the pad are clearly observed. In conclusion, the contact loss nonlinearity is found to be crucial, and as such, it must not be ignored for the squeal source investigation. Finally, the new model offers insight into the squeal initiation process while revealing the limitations of linearized system analyses.

Enormously Low Frictional Surface on Tough Hydrogels Simply Created by Laser-Cutting Process

We measured the friction forces and calculated the friction coefficients of non-processed and laser-processed surfaces of a double network hydrogel (DN gel), which is one of the more famous high-strength gels. The results indicate that laser processing has the ability to reduce the friction coefficients of the gel surfaces. The observation of gel surfaces suggests that the cause of friction reduction is a change in the roughness of the gel surfaces due to laser processing. This finding is expected to lead us to further understanding of the physicochemical properties of hydrogels.