Design of a cell-based straight guidance

Metamaterials exhibit properties which conventional materials do not naturally have. Metamaterial is composed of repeated cells with a specifically designed structure to introduce or improve material properties. In this research, a metamaterial translation mechanism with one degree of freedom is designed. The unit cell for this application consists of a cross-hinge and a cross-spring pivot. By coupling the cross-hinge and cross-spring pivot, a translation in x-direction is created that remains straight with respect to the fixed world. To minimize the drop of the end-effector in y-direction, a position condition is formulated to compensate the negative delta y-displacement due to rotation of the crosshinge, with a positive delta y-displacement due to rotation of the cross-spring pivot. In the end, the maximum drop in y-direction of the end-effector in the unit cell equals 0.007 [µm], which is equal to 0.004 [%] of the stroke in x-direction. To create a metamaterial straight guidance, multiple unit cells are stacked. For the mechanism consisting of two coupled stacks, the maximum drop in y-direction equals 0.013 [µm], which is equal to 0.003 [%] of the stroke in x-direction. The result is a cell-based straight guidance with less parasitic motion than a leaf spring guidance.