Augment Laminar Jamming Variable Stiffness Through Electroadhesion and Vacuum Actuation

    Various variable stiffness mechanisms have been developed to bestow new capabilities for the robotics community by changing the mechanical behaviors of robots. However, variable stiffness is limited in actuation, response speed, stiffness ratio, and, most importantly, modeling. This article proposes hybrid actuated laminar jamming to outperform individual actuated variable stiffness mechanisms. An analytical model for multilayer laminar jamming that accurately characterizes mechanical behaviors in experiments is first built. Comprehensive parametrical analysis based on this model serves as design guidelines for performance improvements of laminar jamming. Feedforward control further proves the validity of the proposed model and exhibits good controllability, showing response speed as fast as 5 ms. The synergy between electroadhesion and vacuum actuation significantly enhances overall performance, resulting in far greater effects than individual contributions. For instance, the proposed device generates a high stiffness that is almost impossible for individual vacuum or electroadhesion. Moreover, vacuuming increases 23% of the breakdown voltage, which leads to a larger electroadhesion force and, hence, a higher stiffness.
Figure 1. Schematic of hybrid actuated laminar jamming for variable stiffness.
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Figure 2. Model-based parametrical analysis for (a) stiffness and (b) force.
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Figure 3. Performance characterization of hybrid actuated laminar jamming. (a) Force and stiffness characterization of two and four-layer structures; (b) Theoretical and experimental comparison in force and deformation at the point of interest.
Figure 4. Coupled vacuum-EA relationship and synergistic effect.

Reference

Chen, C., Ren, H. and Hongqiang Wang*. Augment Laminar Jamming Variable Stiffness Through Electroadhesion and Vacuum Actuation. In IEEE Transactions on Robotics (T-Ro), (41), 819-836.