KEYWORDS: Sensors, Optical scanning, Ferroelectric materials, Control systems, Servomechanisms, System identification, Signal processing, Actuators, Device simulation, Error control coding
Modern optical systems rely on scanning platform not only to broaden the field of view but also to enhance the viewing resolution. This paper presents a computer aided engineering (CAE) approach to a novel high speed optical scanning platform [1]. By the aid of complete system identification, system dynamics simulation and analysis, the resulted scanning platform is able to comply with high performance motion requirements. The optical scanning platform [1] uses piezoelectric transducers (PZT) with flexure joints. The scanning range of the novel optical scanning platform [1] can reach as wide as ±3.84 mrads after feedback. Different scanning reference demands are scheduled with different controllers in an attempt to achieve enhanced resolutions. For step and scan reference commands, we adopt a modified PID controller to obtain an improved performance over the simple PID controllers. The repeated continuous scanning, on the other hand, uses an iterative learning controller (ILC). The scanning resolutions are 10 μrad and 6.67 μrad in each scanning direction when operated under the modified PID controller and the ILC controller, respectively. Experimental results are provided to show the efficacy of the proposed approach.
Recent advancements in precision engineering have promoted the use of high precision servo mechanism to enhance optical system performance. Present servo mechanisms are able to aid the optical resolution by driving the scanning mirrors to achieve higher resolutions than the traditional imaging systems. To compete with the still imaging systems, the servo mechanisms must achieve very high operation speeds while maintaining highly accurate positioning. This paper introduces a novel, high speed, high precision servo mechanism for the optical scanner. The proposed design uses piezoelectric transducers (PZT) with flexure joints in place of the conventional servo motor drive. The arrangement does not suffer from the backlash problem or the problem with slipping during starting. The study uses the dynamics simulation and finite element analysis (FEA) software for simulation and analysis. The FEA results provide information for the structural prosperities such as the vibration modal type, resonance frequencies, steady state deformation... etc. The analytical data then provide the basis to derive a system model for control synthesis. The dynamic simulation of the control system is accomplished by an integration of the control software with the FEA software. The control output updates the FEA results at every frame time during the simulation. The dynamic simulation results provide all the useful physical properties of the mechanism for prototype design references.
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