In this study, we investigated a promising method for measuring three-axis force based on an optical tactile sensing
system. Such system consists of a waveguide, an array of tactile cell, a light source and an image sensor (a CCD
camera). When the tactile cells are subjected to external forces, the condition for total internal reflection of the attached
waveguide is spoiled. The original symmetrical planar waveguide then changes to an asymmetrical one, leading to light
leakage in the transverse direction, which is used as the sensing mechanism for the applied forces. A numerical study
involving three-dimensional finite element analysis was carried out to study the deformation of tactile cells due to
contact forces. A linear relationship between the applied three-axis force and the spot sizes of the image of the leaked
light was obtained and validated by experiments.
In this paper, multivariable linear regression analysis was employed to obtain the relationship among facial geometric
features, and a discriminant function was used to evaluate the significance of different features. Finally, classification
rates were compared with different combinations of geometric features. The results showed that the geometric feature
with more significance probably improved the classification performance in the cases studied.
In order to measure three-axis force, two four-part tactile sensing systems based on piezoelectricity and optics were
designed and fabricated. The feasibility and reliability of the two systems were evaluated both numerically and
experimentally. A general formula between the applied three-axis force and the four-part tactile sensing signals was
developed. It is expected that this formula should benefit the design and fabrication of new tactile sensing systems.
Two micro-optomechanical accelerometers based on Multi-Mode Interference (MMI) couplers were designed and
evaluated in this study. The optical components were optimized with the Parameter Scan Method. According to the
photoelastic effect, the change in refractive index of a waveguide made of crystal materials is related to the mechanical
strains in the waveguide. In this study, such change was calculated using the mechanical strains obtained from the Finite
Element Analysis (FEA) results. Beam Propagation Method (BPM) was used to study the relationship between the input
acceleration and the output optical power and thus the performance of the proposed accelerometers. The results show the
two designs are suitable for different acceleration ranges.
With the development of biometrics technology, the recognition of human-face becomes the most acceptant way of identification. In the recent thirty years, face recognition technology gets more and more attentions. But unfortunately, most human-face recognition systems with a large-scale facial image database can’t be put into practice just because they have not enough recognition speed and precision. As a matter of fact, the recognition time will drastically increase as the number of human-face increases. In order to improve the recognition rates, we can firstly classify the large-scale facial image database into several comparatively small classes with specific criterion, and then begin recognition in the next step. If the classified class is still too big for recognition, another classification could be put into practice with other specific criterion until it adapts to recognition. This method is named as Multi-Layer Classification Method (MLCM) in our paper. In order to classify an unclassified face into a small class, a multiclass classifier must be set up. Because that the mahalanobis distance classifier follows the normal distribution, it is employed in our study. The results have shown that the integrative recognition rates have drastically increased for the large-scale facial image database.
Singular values (SVs) feature vectors of face image have been used for face recognition as the feature recently. Although SVs have some important properties of algebraic and geometric invariance and insensitiveness to noise, they are the representation of face image in its own eigen-space spanned by the two orthogonal matrices of singular value decomposition (SVD) and clearly contain little useful information for face recognition. This study concentrates on extracting more informational feature from a frontal and upright view image based on SVD and proposing an improving method for face recognition. After standardized by intensity normalization, all training and testing face images are projected onto a uniform eigen-space that is obtained from SVD of standard face image. To achieve more computational efficiency, the dimension of the uniform eigen-space is reduced by discarding the eigenvectors that the corresponding eigenvalue is close to zero. Euclidean distance classifier is adopted in recognition. Two standard databases from Yale University and Olivetti research laboratory are selected to evaluate the recognition accuracy of the proposed method. These databases include face images with different expressions, small occlusion, different illumination condition and different poses. Experimental results on the two face databases show the effectiveness of the method and its insensitivity to the face expression, illumination and posture.
As the development of intelligent robots, more and more sensors of higher-technique are required, and tactile sensing technology gets extensively attention. It is the three-axis force that is working when the robot is grasping or walking, but it is quite difficult to measure the three-axis force directly in the numerous tactile sensors. To get the contact-alike nonlinear solution in FEA(Finite Element Analysis), an advanced analysis method of ANSYS - APDL(Advanced Program Description Language) is employed, with which the miscellaneous and time-consuming process is automatically completed in an intelligent way. This paper introduces a series of simulation experiments about an innovative optical wave-guided three-axis tactile sensing system and brings forward the corresponding mathematical model to calculate the three-axis force. A special sensing system is designed for the experiments, and the results
considerably conform to the theoretical analysis. Thus, a new method comes into being for tactile sensing of intelligent robots.
In this paper, a novel method of Regional Facial Geometric Feature Recognition (RFGFR) is presented. With the development of biometrics technology, the recognition of human-face becomes the most acceptant way of identification. Based on the consideration that China is such a country with expansive regions, numerous peoples and different facial geometric structures and features, the six geographic regions based on facial geometric features have been classified according to China Administrative District. The 300 front face images of the Han nationality in the classified six regions have been sampled and registered into a face image gallery through a 3-D digital camera system. Subsequently, some geometric features (distance between two pupils, ratio of distance between two inner canthi to distance between two pupils and etc.) have been extracted and used as the facial feature recognition parameters. Furthermore, through lots of recognition experiments, we found that the Han people in different regions have different facial features to some extent. As a result, the feasibility and reliability of the RFGFR method are finally verified.