María G. Pérez

Robust Control with Dynamic Compensation for Human-Wheelchair System

This work presents the kinematic and dynamic modeling of a human-wheelchair system, and dynamic control to solve the path following problem. First it is proposed a dynamic modeling of the human-wheelchair system where it is considered that its mass center is not located at the center the wheels’ axle of the wheelchair. Then, the design of the control algorithm is presented. This controller design is based on two cascaded subsystems: a kinematic controller with command saturation, and a dynamic controller that compensates the dynamics of the robot. Stability and robustness are proved by using Lyapunov’s method. Experimental results show a good performance of the proposed controller as proved by the theoretical design.

Adaptive cooperative control of multi-mobile manipulators

This paper presents a multi-layer scheme for the adaptive coordinated cooperative control of n mobile manipulator. Each layer works as an independent module, dealing with a specific part of the problem of cooperation, coordination and adaptation, thus giving more flexibility to the scheme. Also, the redundancy of the n mobile manipulators is used for the avoidance of obstacles by the mobile platforms-without deforming the virtual structure and maintaining its desired trajectory- and the singular configuration prevention through the systems manipulability control. Stability and robustness are proved by using Lyapunovs theory. Simulation results show a good performance of the proposed control scheme as proved by the theoretical design.

An approach for automatic segmentation of thermal imaging in Computer Aided Diagnosis

Breast cancer is major cause of the high mortality rates among young women in developing countries. In Latin America, it is a great health problem, as well. For example in Brazil and Ecuador, this is the leading cause of cancer among women around 35 years old. Early detection is important to improve the chance of cure. Thermal imaging has the ability to show regions where there is any potential cancer by indicating areas of the body where there is an abnormal temperature variation. Moreover, thermography can detect suspicious regions in patients of any age, even in cases of dense breasts, where the detection of an abnormality can not be achieved by mammography. An essential step in the use of thermal imaging systems is the development of computer-aided diagnosis (CAD). However, any development towards a CAD system or even an examination guided by computer should consider adequate extraction of the region of interest (ROI). This paper proposes a methodology for automatic segmentation of thermal imaging breast and validation of the results by generating a Ground Truth (GT). The automatic method proposed in this paper consists of several image-processing techniques such as thresholding, clustering, edge detection and refinement, among others. For the evaluation of the results the developed GT are presently available on the Internet, in order to allow proper verification of the results. Finally, the results obtained by the proposed methodology for the 328 images used in this study showed average values of accuracy and sensitivity around 96% and 97%, respectively.

Automatic detection of injuries in mammograms using image analysis techniques

Breast cancer is the most common cancer and the second cause of cancer death among women. Early detection is the key to reducing the associated mortality rate, for this identify the presence of microcalcifications is very important. This paper presents an approach for micro calcification detection in mammography based on the following steps: noise reduction, image segmentation, extraction of the region of interest (ROI) and features that describe the possible asymmetries between the ROI of both breasts. The new aspect of our work is how we detect the microcalcifications by using wavelet decomposition. All decompositions were conducted using orthogonal wavelet filter set to computes the four filters associated with the scaling filter corresponding to a wavelet: low-pass filter and high-pass filter. Several mother families have been tested and we are confident to recommend the coiflets as the best one.