Projects
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Research:
Identification and Modeling of Contact Dynamics of Precise Direct Drive Stages >>
A new decoding method is presented for analog encoders enabling major improvements in both accuracy and resolution. A simulation study and experiments with real, industrial-grade, equipment demonstrate the performance improvement of the proposed
method, revealing that the new method can generate position estimates with accuracy about three times better than that of standard methods. Moreover, in some special cases, the resulting position accuracy can reach sub-nanometer levels, thus enabling further size
reduction in the semiconductor industry. The proposed algorithm also yields velocity estimates better by about two orders of magnitude than those obtained with standard methods.
Traditional scanning mirrors are designed to operate under resonance conditions thus exhibiting low losses and requiring a small driving force/torque. Indeed these devices can achieve large scan angles and low driving forces creating a sinusoidal scanning motion. For some applications, a uniform scanning rate is required and operation in a single resonance frequency does not provide satisfactory results. Unfortunately,
the requirement to obtain a non-sinusoidal periodic motion profile increases the required forces to a degree depending on the scanning frequency and the physical behavior of the device. In this work we introduce a novel idea with which a nearly triangular shaped scanning profile is obtained by suitable synthesis of the structural dynamics.
A new automatic method to tune the parameters of high order linear controllers is presented. The auto-tuning is achieved by minimizing, without constraints, a cost function that is related to the open loop shaping problem.
The effort demanded from the designer is similar to that required to tune a low order controller such as PI or PID. The capabilities of the new method are demonstrated on two examples.
Identification and Modeling of Contact Dynamics of Precise Direct Drive Stages
This paper presents a novel Hilbert transform–based identification technique to capture nonlinear tangential elastic and friction forces in submicron motions. Validated on a linear-motor stage under low-frequency excitation (1–40 Hz), the method simultaneously recovers contact dynamics from experimental data to support improved closed-loop control development.
The Fast Steering Mirror (FSM) is commonly used for many applications. Among the applications one can count optical switches, image
rendering, beam positioning, tracking, etc. The FSM consists of a mirror
placed on a torsional flexure. Together with an actuation mechanism it can
perform angular motion. The actuation mechanism is mostly electromagnetic
for macro scale FSM, or electrostatic, or micro electromechanical system
(MEMS), in a micro scale FSM. It can be operated in open or in closed loop.
The flexure plays the role of torsion spring that together with the mirror
inertia generates an essentially 2nd order system plant with weakly damped
poles, i.e. with resonance dynamics.
Adaptive Current Control Method by Online Estimation the Motor Coil’s Resistance using EKF and UKF
This paper presents a Kalman filter-based approach for real-time estimation of coil resistance in DCBL systems experiencing temperature variations and bandwidth limitations.
The estimated resistance is used to adaptively tune the PI controller’s integral gain, improving closed-loop performance.
An augmented state-space model captures coupled electrical and thermal dynamics, including unknown ambient temperature.
Simulations using both EKF and UKF show accurate estimation and enhanced control, with UKF offering slightly faster convergence.
This paper presents a method for identifying non-linear dynamics in closed-loop micro-gyroscope systems. By analyzing closed-loop response characteristics, the technique isolates structural and electrostatic nonlinearities to optimize control stability and performance.
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