A brief discussion of a previously designed parallel plate micro-actuator is provided. Theoretical models for the parallel plate design are then developed to motivate models used in the control design and to illustrate non-linear effects of the parallel plate design. Electrostatic simulations are performed for a comb finger, high aspect ratio micro-actuator geometry to illustrate non-linear effects in an alternative design approach. These simulations show a significant amount of non-linearity in comb fingers under certain operating conditions, though they also show the geometries necessary for linear operation.
Initial continuous-time control designs for the dual-stage servo have been designed and simulated using Matlab's p-tools. Single-inputlsingle-output (SISO) and multi-inputlmulti-output (MIMO) control design methods have been shown to be capable of meeting specified uncertainty and performance specifications. Uncertainty models have included bearing effects in the disk drive arm as well as high frequency dynamics not included in the system model. Simulations using a linearized system model with the SISO design achieved a low frequency disturbance rejection of 59 dB with a bandwidth of 2.0 kHz. The MIMO design also achieved a low frequency disturbance rejection of 59 dB with a bandwidth of 3.0 kHz. The p-tools design procedure and software for both design methods is also described.