This Ring Gyroscope is constructed from an outer ring, eight semicircular support springs, drive, sense and control electrodes, see Figure 1. The Gyroscope has two identical elliptically-shaped flexural-modes of that are of equal frequency and separated by a 45 degree angle, see Figure 2. The ring is excited electrostatically into the primary flexural mode, and held at a fixed amplitude. As device is subjected to rotation around its normal axis, Coriolis force causes energy to be transferred from the primary mode to the secondary mode, causing the secondary mode amplitude to increase. This amplitude change is sensed capacitively.
Architect can be used to build a fully parametric 3D model of the Gyroscope using beams and electrodes from the Parameterized ElectroMechanical (PEM) parts library. Figure 3 shows the schematic of the Gyroscope. In the schematic, a sub-assembly has been used to represent the eight springs in the gyroscope. This makes it easier to construct and understand the schematic. Figure 3a shows the top level schematic while figure 3b shows the lower level hierarchical element. The semicircular support spring is modeled using a combination of 'Arc beam' and 'Beam' components from the PEM parts library.
Figure 3: Hierarchical Ring Gyroscope schematic in Architect, (a) top level schmatic and (b) lower level hierarchical elements
Note that process variations can cause asymmetry in the ring structure which will lead to separation of the modes. Architect can help you understand the separation in resonances with process variation.
Figure 5: Animation showing first flexural mode. For clarity, the displacement is scaled up by a factor of 5000
Nombre: Lenny D. Ramirez C.
Ver blogg: http://lennyramirez-crf3.blogspot.com/