(1963). Cybernetics, or Control and Communication in the Animal and the Machine. Technometrics: Vol. 5, No. 1, pp. 128-130.

Cybernetics, or Control and Communication in the Animal and the Machine

As a robust nonlinear similarity measure in kernel space, correntropy has received increasing attention in domains of machine learning and signal processing. In particular, the maximum correntropy criterion (MCC) has recently been successfully applied in robust regression and filtering. The default kernel function in correntropy is the Gaussian kernel, which is, of course, not always the best choice. In this paper, we propose a generalized correntropy that adopts the generalized Gaussian density (GGD) function as the kernel, and present some important properties. We further propose the generalized maximum correntropy criterion (GMCC) and apply it to adaptive filtering. An adaptive algorithm, called the GMCC algorithm, is derived, and the stability problem and steady-state performance are studied. We show that the proposed algorithm is very stable and can achieve zero probability of divergence (POD). Simulation results confirm the theoretical expectations and demonstrate the desirable performance of the new algorithm.

Generalized Correntropy for Robust Adaptive Filtering

Maximum correntropy Kalman filter

Effective connectivity: Influence, causality and biophysical modeling

The maximum correntropy criterion (MCC) has received increasing attention in signal processing and machine learning due to its robustness against outliers (or impulsive noises). Some gradient based adaptive filtering algorithms under MCC have been developed and available for practical use. The fixed-point algorithms under MCC are, however, seldom studied. In particular, too little attention has been paid to the convergence issue of the fixed-point MCC algorithms. In this letter, we will study this problem and give a sufficient condition to guarantee the convergence of a fixed-point MCC algorithm.

Convergence of a Fixed-Point Algorithm under Maximum Correntropy Criterion

The invention discloses a planar motor driven magnetic suspension coarse/micro motion integrated reticle stage. The coarse/micro motion integrated reticle stage comprises a coarse/micro motion integrated reticle stage moving table, a balance mass, a driving motor, a mask plate, a base, a vibration isolation system and a measurement system, wherein the vibration isolation system is positioned between the balance mass and the base; the mask plate is arranged on the coarse/micro motion integrated reticle stage moving table; a driving motor of the reticle stage moving table is a moving iron type planar motor; a rotor of the planar motor is a permanent magnet array arranged on the top surface of the coarse/micro motion integrated reticle stage moving table; a stator of the planar motor is a coil array arranged on the balance mass. The design complexity of the driving motor of the reticle stage moving table can be lowered; compared with a linear motor, the planar motor can provide thrust in multiple directions, and the number of motors is reduced, so that the coarse/micro motion integrated reticle stage moving table is compact in structure, the inherent frequency and the control bandwidth of the coarse/micro motion integrated reticle stage movable table are improved, and the control precision is further improved.

Planar motor driven magnetic suspension coarse/micro motion integrated reticle stage

In this paper, a general self-calibration theory framework is presented for three-dimensional precision stages to determine the stage error Four measurement views of a cubic artifact on the three-dimensional precision stage are utilized to provide the symmetry, transitivity and redundance The firstorder components of the stage error, ie, the nonorthogonality and the scale difference, are determined through the first three measurement views And the residual components of the stage error are then figured out by a least-square based calculation law, which completes the stage error determination Additionally, the parasitic errors related to the artifact and the misalignment errors of all measurement views can all be identified through algebraic manipulations Computer simulation is finally carried out and the results validate that the proposed algorithm can accurately realize the stage error The proposed scheme actually provides a framework as a principle to solve the three-dimensional self-calibration problem for practical engineers

Three-dimensional stage self-calibration: A general theory framework

As previous self-calibration technologies are mostly limited to X, XY, XYZ, and angular metrology stages, we study the self-calibration of precision XYθz metrology stages and present an on-axis self-calibration strategy. Specifically, a designed artifact plate with grid mark lines and angular mark lines whose accuracy is not precisely known, is presented as the assistant tool. And four measurement views of the designed artifact plate on the uncalibrated XYθz stage are fully utilized to provide the symmetry, transitivity and redundance of the XYθz systematic measurement error (i.e., stage error). In addition, circle closure principle is employed for the angular stage error component. Resultantly, a least-square based calculation law is proposed for the final determination of the stage error. Computer simulation is conducted and the calculation results validate that the proposed scheme can accurately realize the stage error even under the existence of various random measurement noises. As an integration of XY self-calibration and angular self-calibration, the proposed scheme solve the XYθz self-calibration problem, and possesses special merits such as simplifying the mathematical processing for calculation of misalignment errors.

On-axis self-calibration of precision XYθ z metrology systems: An approach framework

A heterodyne grating interferometer displacement measurement system, comprising a reading head (1), a measurement grating (2) and an electronic signal processing component (3). The reading head (1) comprises a dual-frequency laser generator (11), an interferometer (12), a reference signal photo-electric conversion unit (13) and a measurement signal photo-electric conversion unit (14). The dual-frequency laser generator (11) comprises a laser tube (111), a first polarization spectroscope (112), an acousto-optic modulator, a mirror, a polaroid and a spectroscope (113). The interferometer (12) comprises a second polarization spectroscope (121), a wave plate, a refraction element (123) and a reflector (124). Laser light emitted from the laser tube (111) is collimated, passes through the first polarization spectroscope (112), and then emits two light beams with a vertical polarization direction and a vertical propagation direction; the two light beams pass through two acousto-optic modulators and respectively generate two first-order diffraction light beams with different frequencies, which are later divided into reference light and measurement light; two parallel reference light beams form a beat frequency electric signal with positive and negative first-order diffraction measurement light respectively after passing through a measurement signal photo-electric conversion unit (14); the beat frequency signals are transmitted to the electronic signal processing component (3) for signal processing, thus the output of linear displacement in two directions is realized.

Heterodyne grating interferometer displacement measurement system

Mean-squared error (MES) can at best provide biased solution in the presence of additive disturbances (both correlated and white) on the input and the output signals. However, in the system identification of unmanned aerial vehicle (UAV), typically, in the takeoff, the UAV suffers serious disturbance e.g. wind gusts, turbulence, ground influence and sampling noise. For EWC, we can get the unbiased parameter estimation in white noise, and the system identification in this paper prove the noise rejection ability of EWC. EWC (error whitening criterion) was first put forward by Mr. Rao in 2002 and applied in filtering, and further developed theoretically. But EWC has not been applied in practical problems yet. This paper applies EWC in the system identification of real self-developed UAV's takeoff motion, and compares the result of EWC-LMS with traditional LMS (least mean square) and TLS (total least square). The result shows that in comparison with traditional LMS and TLS, EWC-LMS improve the performance significantly

Jinchun Hu

Papers

Planar motor driven magnetic suspension coarse/micro motion integrated reticle stage

Three-dimensional stage self-calibration: A general theory framework

On-axis self-calibration of precision XYθ z metrology systems: An approach framework

Heterodyne grating interferometer displacement measurement system

System Identification of UAV Based on EWC-LMS