Robust Pose Control of Robot Manipulators Using Conformal Geometric Algebra

A controller, based on sliding mode control, is proposed for the n-link robotic manipulator pose tracking problem. The point pair (a geometric entity expressed in geometric algebra) is used to represent position and orientation of the end-effector of a manipulator. This permits us to express the direct and differential kinematics of the endeffector of the manipulator in a simple and compact way. For the control, a sliding mode controller is designed with the following properties: robustness against perturbations and parameter variations, finite time convergence, and easy implementation. Finally, the application, of the proposed controller in a 6 DOF robotic manipulator is presented via simulation.Consejo Nacional de Ciencia y Tecnologí

On the Discretization of a Class of Homogeneous Differentiators

This paper proposes explicit and implicit discrete-time realizations for a class of homogeneous sliding-mode-based differentiators. The proposed approach relies on the exact discretization of the continuous differentiator. Also, it is demonstrated that the proposed implicit discretization always exists, is non-anticipative and unique. A numerical simulation shows the better performance of the implicit scheme over the proposed and the referenced explicit implementations.ITESO, A.C

Power Line Inspection Via an Unmanned Aerial System Based on the Quadrotor Helicopter

The inspection of high voltage power transmission lines is mainly carried out by manned aerial vehicles or foot patrol. However, these maintenance methodologies for inspection are somehow inefficient and expensive. Moreover, helicopter assisted inspection endangers the human life. Recently, unmanned aerial vehicles have been under development in several research centers all over the world due to its potential applications. In this paper, we present an unmanned aerial system based on the quadrotor helicopter for high voltage power line inspection. Our interest is to equip the quadrotor helicopter with the necessary payload in order to be able to carry out a qualitative inspection, therefore the hardware architecture of the aerial robotic system is presented. Finally, some experimental results are shown to demonstrate the feasibility of the proposed system.ITESO, A.C

Discretization of the Robust Exact Filtering Differentiator Based on the Matching Approach

This paper presents a time discretization of the robust exact filtering differentiator, a sliding mode differentiator coupled to filter, which provides a suitable approximation of the derivatives for some noisy signals. This realization rely on the stabilization of a pseudo linear discrete-time system, it is attained through the matching approach. As in the original case, the convergence of the robust exact filtering differentiator depends on the bound of a higher-order derivative. Nevertheless, this new realization can be implemented with or without the knowledge of such constant. It is demonstrated that the system trajectories converge to a neighborhood of the origin for a free-noise input. Finally, comparisons between the behavior of the differentiator with different design parameters are presented.ITESO, A.C

Visual Servoing and Robust Object Manipulation Using Symmetries and Conformal Geometric Algebra

Object tracking and manipulation is an important process for many applications in robotics and computer vision. A novel 3D pose estimation of objects using reflectionally symmetry formulated in Conformal Geometric Algebra (CGA) is proposed in this work. The synthesis of the kinematics model for robots and a sliding mode controller using the CGA approach is described. Real time implementation results are presented for the pose estimation of object using a stereo vision system.ITESO, A.C.CINVESTA

CONCOMITANT CARDIOVASCULAR DISEASES AND ANTIHYPERTENSIVE TREATMENT IN OUTPATIENT PRACTICE (BY THE RECVASA REGISTRY DATA)

Aim. To study a pattern of concomitant cardiovascular diseases (CVDs) and to estimate particularities and quality of medical antihypertensive therapy in hypertensive patients in real outpatient practice with a help of the Registry in Ryazan region.Material and methods. A total of 3690 patients with hypertension, ischemic heart disease, chronic heart failure and atrial fibrillation, who had attended general practitioners and cardiologists of 3 outpatient clinics in Ryazan city, were enrolled in the outpatient Registry of cardiovascular diseases (RECVASA). The diagnosis of hypertension was recorded in 3648 of 3690 (98.9%) outpatient charts, 28.1% of the subjects were men and 71.9% - women.Results. A total of 2907 (79.7%) of 3648 patients had combination of hypertension with other CVDs. Combination of 3-4 cardiovascular diagnoses was registered in 63.8% of the cases. 11.5% and 9.5% of the patients had a history of myocardial infarction and cerebral stroke, respectively. Diagnosis of hypertension was verified in 448 of 450 randomized hypertensive patients (99.6%). The incidence of prescription of one and two antihypertensive drugs (AHDs) was 25% and 39%, respectively, of 3 AHDs – 21%, 4 and more – 2%. AHDs were not prescribed in 13% of hypertensive patients. The mean number of prescribed AHDs was 1.73. The mean incidence rate of target blood pressure achievement was 26.1%. We have noted insufficient ACE inhibitors/angiotensin receptor blockers (ARB) and beta-blockers prescription in different concomitant CVDs. Patients with 3-4 cardiovascular diagnoses were more often prescribed combined antihypertensive treatment. Prescription of ACE inhibitors/ARB, beta-blockers and thiazide diuretics combination was preferable in 74.1% of the cases, when taking into account absolute and relative contraindications for betablockers use – in 64.0%. 15.2% of the hypertensive patients used reimbursed drugs for CVDs at the moment of the Registry enrollment as compared with 39.2% in previous years (p<0.05).Conclusion. The RECVASA study data allowed revealing high incidence of concomitant CVDs in hypertensive patients, insufficient use of combined antihypertensive treatment, including AHDs with proved favorable influence on prognosis. Achievement of concordance of medical treatment to national and international guidelines, taking into account concomitant CVDs, and optimization of patients’ coverage with reimbursed drugs are the main reserves for antihypertensive treatment quality improvement