Event-Triggered Control for a Three DoF Manipulator Robot

In the classical approach of Time-Triggered Control (TTC),  the control signal is updated  at  each  sampling  time  as  well  as  the  system  states  to  be  controlled,  which could imply a redundancy in the computational calculation as well as in the transfer of information in the regulation objective. On the other hand, the Event-Triggered Control (ETC) approach performs the same task in an asynchronous way, i.e,, it only updates the control signal when a performance requirement is violated and the states are updated at each sampling time. This reduces the amount of computational calculation without affecting the performance of the closed loop system. For this reason, in the present work the ETC is developed for the stabilization of a manipulator robot with three Degree of Freedom (DoF) in the joint space where a Lyapunov Control Function (LCF) is proposed to formulate the event function (e¯), which indicates whether or not  is required  the  control  signal  updating.  Simulation results show the reduction of the updates compared with a TTC

Event-Triggered Control for a Three DoF Manipulator Robot

In the classical approach of Time-Triggered Control (TTC),  the control signal is updated  at  each  sampling  time  as  well  as  the  system  states  to  be  controlled,  which could imply a redundancy in the computational calculation as well as in the transfer of information in the regulation objective. On the other hand, the Event-Triggered Control (ETC) approach performs the same task in an asynchronous way, i.e,, it only updates the control signal when a performance requirement is violated and the states are updated at each sampling time. This reduces the amount of computational calculation without affecting the performance of the closed loop system. For this reason, in the present work the ETC is developed for the stabilization of a manipulator robot with three Degree of Freedom (DoF) in the joint space where a Lyapunov Control Function (LCF) is proposed to formulate the event function (e¯), which indicates whether or not  is required  the  control  signal  updating.  Simulation results show the reduction of the updates compared with a TTC

ROBOT MÓVIL (3,0) UNA EVALUACIÓN DE RENDIMIENTO

ResumenEn la actualidad existe una gran demanda de sistemas robóticos que presenten un alto grado de precisión y repetibilidad con el propósito de obtener productos de mejor calidad. Uno de los aspectos claves para desarrollar sistemas con un buen desempeño es el sistema de posicionamiento y control. Por tal motivo en el presente trabajo se expone la evaluación de rendimiento de un sistema de posicionamiento con base en odometría y el sistema de control de un robot móvil 3.0. La evaluación del sistema de control se obtiene con base en el cálculo de la repetibilidad, obtenido a través del sistema de odometría del robot móvil. Por otra parte, la exactitud del sistema de localización con base en odometría se compara con los resultados obtenidos de un sistema de localización de faros activos basado en cámaras. Bajo el estándar internacional ISO-9283 se observa que la repetibilidad y la exactitud del robot móvil son apropiadas.Palabras Claves: Exactitud, ISO-9283, repetibilidad, robot móvil 3.0, sistema de localización.MOBILE ROBOT (3,0) A PERFORMANCE EVALUATIONAbstractNowadays, robotic systems with a high accuracy and repeatability are highly used due to the requirement to obtain a superior quality in the final product. One of the main issue to carry out systems with “good” performance is the positioning and control system. For this reason, a positioning performance evaluation based on both odometry and control system of a 3.0 mobile robot, is presented in this work. The control performance evaluation is obtained by computing the repeatability using the obtained result from the odometry system of the mobile robot. On the other hand, the performance of the location system based on odometry is compared by the results obtained with a camera based active beacon location system in order to determine its accuracy. Using the International Standard ISO-9283, the repeatability and accuracy of the mobile robot is suitable.Keywords: Accuracy, ISO-9283, location system, mobile robot 3.0, repeatability

Optimum Design of Parallelogram Five-bar Manipulator for Dexterous Workspace by using ELEMAEF in Differential Evolution

The kinematic design of mechanism is an important stage in the design methodology. A dexterous workspace for a manipulator is an outstanding characteristic that must be considered in it. Hence, a mono-objective constraint optimization problem (MOCOP) for the kinematic design of a manipulator with three revolute joints (3R robot), that fulfils a defined dexterous workspace, is formulated. The MOCOP is solved by proposing a mechanism in the differential evolution (DE) algorithm called exhaustive local exploitation mechanism with adaptive scale factor (ELEMAEF). This mechanism exhaustively exploits a local region in the search space with the information of the base and the difference vectors of good trial vector, in an attempt to generate better individuals in the same direction. In addition, the ELEMAEF guides the evolution of the population toward a better zone without sacrificing the search capabilities of the DE algorithm. A comparison of the DE algorithm with and without the ELEMAEF for this particular design problem is presented. The use of the ELEMAEF gives a superior performance in the DE algorithm

Trends and outcome of neoadjuvant treatment for rectal cancer: A retrospective analysis and critical assessment of a 10-year prospective national registry on behalf of the Spanish Rectal Cancer Project

Introduction: Preoperative treatment and adequate surgery increase local control in rectal cancer. However, modalities and indications for neoadjuvant treatment may be controversial. Aim of this study was to assess the trends of preoperative treatment and outcomes in patients with rectal cancer included in the Rectal Cancer Registry of the Spanish Associations of Surgeons. Method: This is a STROBE-compliant retrospective analysis of a prospective database. All patients operated on with curative intention included in the Rectal Cancer Registry were included. Analyses were performed to compare the use of neoadjuvant/adjuvant treatment in three timeframes: I)2006–2009; II)2010–2013; III)2014–2017. Survival analyses were run for 3-year survival in timeframes I-II. Results: Out of 14, 391 patients, 8871 (61.6%) received neoadjuvant treatment. Long-course chemo/radiotherapy was the most used approach (79.9%), followed by short-course radiotherapy ± chemotherapy (7.6%). The use of neoadjuvant treatment for cancer of the upper third (15-11 cm) increased over time (31.5%vs 34.5%vs 38.6%, p = 0.0018). The complete regression rate slightly increased over time (15.6% vs 16% vs 18.5%; p = 0.0093); the proportion of patients with involved circumferential resection margins (CRM) went down from 8.2% to 7.3%and 5.5% (p = 0.0004). Neoadjuvant treatment significantly decreased positive CRM in lower third tumors (OR 0.71, 0.59–0.87, Cochrane-Mantel-Haenszel P = 0.0008). Most ypN0 patients also received adjuvant therapy. In MR-defined stage III patients, preoperative treatment was associated with significantly longer local-recurrence-free survival (p < 0.0001), and cancer-specific survival (p < 0.0001). The survival benefit was smaller in upper third cancers. Conclusion: There was an increasing trend and a potential overuse of neoadjuvant treatment in cancer of the upper rectum. Most ypN0 patients received postoperative treatment. Involvement of CRM in lower third tumors was reduced after neoadjuvant treatment. Stage III and MRcN + benefited the most

Parametric redesign of the Pendubot for vertical positioning in minimum time

[EN] A parametric redesign methodology of nonlinear systems for minimum-time control without constraints on the state trajectory and bounded control is proposed. This methodology states the optimum redesign problem as a dynamic optimization one. This methodology simultaneously finds both the structural parameters of the system and the switching intervals of the control signal which minimize the required time to take the system from an initial state to a final one. Experimental results applying the minimum-time control methodology and the parametric redesign methodology to the Pendubot are shown.[ES] Se propone una metodología de rediseño paramétrico de sistemas no lineales para control en tiempo mínimo sin restricciones de trayectoria en los estados y con control acotado. Tal metodología consiste en plantear el problema de rediseño óptimo como uno de optimización dinámica, permitiendo encontrar simultáneamente los parámetros estructurales del sistema y los instantes de conmutación de la señal de control que minimizan el tiempo requerido para llevar al sistema de un estado inicial a uno final. Se muestran resultados experimentales del Pendubot original con control en tiempo mínimo y del Pendubot rediseñado siguiendo la metodología propuesta.Cruz-Villar, CA.; Alvarez-Gallegos, J.; Villarreal-Cervantes, MG. (2008). Rediseño paramétrico del Pendubot para posicionamiento vertical en tiempo mínimo. Revista Iberoamericana de Automática e Informática industrial. 5(1):104-114. http://hdl.handle.net/10251/145828OJS1041145

Task Based Mechatronic System Design using Differential Evolution Strategies

Abstract. A dynamic design approach for a mechatronic system called task based mechatronic system design approach (TBMSDA) is stated as a nonlinear dynamic optimization problem (NLDOP) and it is solved by using a differential evolution technique. The design of a parallel robot is carried out by this approach which integrates in a simultaneous way both the structure design parameters of a parallel robot and the PID controller gains in order to improve the position errors and the robot dexterity for executing a specific task. The TBMSDA considers the dynamic system as an equality constraint into the optimization problem. Through the TBMSDA, an optimal combination of the structure and PID controller gains for a planar five-bar parallel robot is obtained. Simulation results show the effectiveness of this design approach

Rediseño paramétrico del pendubot para posicionamiento vertical en tiempo mínimo

Resumen: Se propone Una metodología de rediseilo paramétrico de sistema no lineales para control en tiempo mínimo sin restricciones de trayectoria en losestados y con control a.cotado. Tal metodología. consiste en plantear el problema de rediseño óptimo como uno de optimización dinámica, permitiendo encontrar simultáneamente los parámetros estructurales del sistema y los instantes de conrnlltación de la señal de control que minimizan el tiempo requerido para llevar al sistema de un estado inicial a uno final. Se muestran resultados experimentales del Pendubot original con control en tiempo mínimo y del Pendubot rediseñado siguiendo la metodología propuesta. Palabras clave: Diseño integrado, Rediserlo paramétrico, Optimización dinámica, Pendubot, Tiempo mínim

Empirical Study of Constraint-Handling Techniques in the Optimal Synthesis of Mechanisms for Rehabilitation

Currently, rehabilitation systems with closed kinematic chain mechanisms are low-cost alternatives for treatment and health care. In designing these systems, the dimensional synthesis is commonly stated as a constrained optimization problem to achieve repetitive rehabilitation movements, and metaheuristic algorithms for constrained problems are promising methods for searching solutions in the complex search space. The Constraint Handling Techniques (CHTs) in metaheuristic algorithms have different capacities to explore and exploit the search space. However, the study of the relationship in the CHT performance of the mechanism dimensional synthesis for rehabilitation systems has not been addressed, resulting in an important gap in the literature of such problems. In this paper, we present a comparative empirical study to investigate the influence of four CHTs (penalty function, feasibility rules, stochastic-ranking, and ϵ-constraint) on the performance of ten representative algorithms that have been reported in the literature for solving mechanism synthesis for rehabilitation (four-bar linkage, eight-bar linkage, and cam-linkage mechanisms). The study involves analysis of the overall performance, six performance metrics, and evaluation of the obtained mechanism. This identified that feasibility rules usually led to efficient optimization for most analyzed algorithms and presented more consistency of the obtained results in these kinds of problems

Towards integrating 3D printing and automated assembly

Recent interest in additive manufacturing (AM) technologies (also known as 3D printing) has led to embedding multi-material and electronic components into 3D-printed structures. However, current 3D printing technologies fail to provide all the required materials to fabricate complex devices. Besides, the process of inserting individual building blocks into the impression is usually carried out manually. This paper presents the design of a robot that integrates 3D printing and automated assembly. The robot utilises two modules. The first module fabricates the body of a device by using fused deposition modelling (FDM) technology. The second module grasps pre-assembled building blocks and inserts them into the device. To this end, the feasibility of this integration is validated with the fabrication of a device (non-fabricable with traditional 3D printers) that contains a development board