As per the MEMS actuator roadmap one area of investigation is designing a linkage system in order to act as an interface between the actuator and the paper hinge.

The linkage is necessary in particular because of the constraints of the actuator as listed below:

  1. The system is linearly actuated.
  2. The reach of the actuator is between 10-50% of the length of its body .
  3. The actuator cannot handle any out of plane forces.

The first issue is that it is necessary to convert the linear motion of the actuator into revolute motion about the hinge. There are many simple linkages that perform this task, the most common of which is the simple crank mechanism. The issue with using such a mechanism is stated in the third constaint. The MEMS actuators are extremely sensitive to out of plane forces and since the crank mechanism requires a guide in order to produce straight line motion it requires out of plane forces.

The solution to this problem comes in the form of the Peaucellier–Lipkin linkage. Invented in 1864 the linkage was the first of its kind that could generate a perfectly straight line with no guided assistance. The proof for this is in the literature and is based on the principle of the inversion of a circle.

The issue with the standard Peaucellier–Lipkin linkage relates to the second constraint of the Mems actuators. They have a very small angular displacement for a large linear displacement. As a solution to this issue the alternative Peaucellier–Lipkin linkage can be used. The difference between the two linkages is that the rhombus in the standard linkage is inverted in the alternative linkage. The result of this inversion is that linkage generates a large angular displacement for a small linear displacement.

The alternative Peaucellier–Lipkin linkage therefore satisfies all of the constraints as listed above. The issue, however is the physical implementation of the linkage using paper. However it is a step in the right direction towards actuating a hinge using MEMS actuators.

Nathan Pilbrough

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