Variable stiffness structures lie at the nexus of soft robotics and traditional robotics as they enable the execution of both high-force tasks and delicate manipulations. Laminar jamming structures, which consist of thin sheets encased in a sealed chamber, can alternate between a rigid state when a vacuum is applied and a flexible state when the layers are allowed to slide in the absence of a pressure gradient. These structures have gained popularity in recent years as they lend themselves well to soft robotics applications. In this work, an additional mode of controllability is added by clamping and unclamping the ends of a simple laminar jamming beam structure. Other researchers have focused on the translational degree of freedom that may be controlled via vacuum pressure; here we introduce a rotational degree of freedom that may be independently controlled by a clamping mechanism. Preliminary results demonstrate the ability to switch between three states: high stiffness (under vacuum), translational freedom (with clamped ends, no vacuum), and rotational freedom (with ends free to slide, no vacuum). The humans and many other animals possess different types of joints including synarthrosis and amphiarthroses which allow little to no movement, gliding synovial joints which allow translation but very little rotation, and angular synovial joints which allow bending. Each of these joint types can be enacted by the 3 different stiffness states of the laminar jamming beam with end clamping. Thus, a single device can perform three different types of biologically inspired movements. The highly controllable degrees of freedom offered by laminar jamming structures with end clamping could enable soft robot joints matching the capabilities of these three different classes of human joints, enabling adept movements and stiffness control soft robotics.


Controlling the Rotational DOF of Laminar Jamming Structures With End Clamping Mechanism

Division / Sponsors: 
Aerospace Division

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2020/volume/84027

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