Vision-Based Hybrid Controller to Release a 4-DOF Parallel Robot from a Type II Singularity

[EN] The high accuracy and dynamic performance of parallel robots (PRs) make them suitable to ensure safe operation in human¿robot interaction. However, these advantages come at the expense of a reduced workspace and the possible appearance of type II singularities. The latter is due to the loss of control of the PR and requires further analysis to keep the stiffness of the PR even after a singular configuration is reached. All or a subset of the limbs could be responsible for a type II singularity, and they can be detected by using the angle between two output twist screws (OTSs). However, this angle has not been applied in control because it requires an accurate measure of the pose of the PR. This paper proposes a new hybrid controller to release a 4-DOF PR from a type II singularity based on a real time vision system. The vision system data are used to automatically readapt the configuration of the PR by moving the limbs identified by the angle between two OTSs. This controller is intended for a knee rehabilitation PR, and the results show how this release is accomplished with smooth controlled movements where the patient¿s safety is not compromised.This research was funded by the FEDER-CICYT project with reference PID2020-119522RBI00 (ROBOTS PARALELOS DE REHABILITACION: DETECCION Y CONTROL DE SINGULARIDADES EN PRESENCIA DE ERRORES DE MANUFACTURA), Spain.Pulloquinga-Zapata, J.; Escarabajal-Sánchez, RJ.; Ferrándiz, J.; Vallés Miquel, M.; Mata Amela, V.; Urízar, M. (2021). Vision-Based Hybrid Controller to Release a 4-DOF Parallel Robot from a Type II Singularity. Sensors. 21(12):1-21. https://doi.org/10.3390/s21124080121211

Identification of Inertial Parameters for Position and Force Control of Surgical Assistance Robots

[EN] Surgeries or rehabilitation exercises are hazardous tasks for a mechanical system, as the device has to interact with parts of the human body without the hands-on experience that the surgeon or physiotherapist acquires over time. For various gynecological laparoscopic surgeries, such as laparoscopic hysterectomy or laparoscopic pelvic endometriosis, Uterine Manipulators are used. These medical devices allow the uterus to be suitably mobilized. A gap needs to be filled in terms of the precise handling of this type of devices. In this sense, this manuscript first describes the mathematical procedure to identify the inertial parameters of uterine manipulators. These parameters are needed to establish an accurate position and force control for an electromechanical system to assist surgical operations. The method for identifying the mass and the center of mass of the manipulator is based on the solution of the equations for the static equilibrium of rigid solids. Based on the manipulator inertial parameter estimation, the paper shows how the force exerted by the manipulator can be obtained. For this purpose, it solves a matrix system composed of the torques and forces of the manipulator. Different manipulators have been used, and it has been verified that the mathematical procedures proposed in this work allow us to calculate in an accurate and efficient way the force exerted by these manipulators.The authors wish to thank the "Agencia Valenciana de la Innovacio" (Generalitat Valenciana) for the partial funding of this study under the project with reference INNCON00/20/002. We also want to thank the "Instituto Universitario de Automatica e Informatica Industrial (ai2)" of the "Universitat Politecnica de Valencia" for its financial support under the program "Plan de ayudas a la I+D+I del Instituto ai2".Zamora-Ortiz, P.; Carral-Alvaro, J.; Valera Fernández, Á.; Pulloquinga-Zapata, J.; Escarabajal-Sánchez, RJ.; Mata Amela, V. (2021). Identification of Inertial Parameters for Position and Force Control of Surgical Assistance Robots. Mathematics. 9(7):1-16. https://doi.org/10.3390/math9070773S1169

Imitation Learning-Based System for the Execution of Self-Paced Robotic-Assisted Passive Rehabilitation Exercises

[EN] The development of robotic-assisted rehabilitation exercises involving physical human-robot interaction requires extreme care since an injured limb may be in physical contact with the robot, so compliant behavior is imperative for these tasks. Typical approaches involve force control schemes like admittance controllers that allow humans to adapt the motion. However, when the patient¿s limb has limited mobility or is potentially injured, unintentional forces may occur during the robot¿s trajectory that could be incompatible with these controllers. This letter addresses a new way of generating compliant trajectories for passive rehabilitation exercises, considering that previous positions of the trajectory are attainable for the patient, so reversing the trajectory is a safe op eration. Since there is no clear way to optimize such a goal due to the physiological variability among patients, the condition of reversal is based on imitation learning by taking the analogous healthy limb of the patient as a reference and encoding the forces using Gaussian Mixture Regression, and reversibility is accomplished by means of Reversible Dynamic Movement Primitives. The system allows for self-paced rehabilitation exercises by back-and-forth movements along the trajectory according to the patient¿s reaction, and it has been successfully applied to a 4-DOF parallel robot for lower-limb rehabilitation.This work was supported in part by the Fondo Europeo de Desarrollo Regional under Grant PID2021-125694OB-I00, in part by the Vicerrectorado de Investigación de la Universitat Politècnica de València under Grant PAID-11-21, and in part by the Ministerio de Universidades, Gobierno de España under Grant FPU18/05105Escarabajal-Sánchez, RJ.; Pulloquinga-Zapata, J.; Zamora-Ortiz, P.; Valera Fernández, Á.; Mata Amela, V.; Vallés Miquel, M. (2023). Imitation Learning-Based System for the Execution of Self-Paced Robotic-Assisted Passive Rehabilitation Exercises. IEEE Robotics and Automation Letters. 8(7):4283-4290. https://doi.org/10.1109/LRA.2023.3281884428342908

Optimal Reconfiguration of a Parallel Robot for Forward Singularities Avoidance in Rehabilitation Therapies. A Comparison via Different Optimization Methods

[EN] This paper presents an efficient algorithm for the reconfiguration of a parallel kinematic manipulator with four degrees of freedom. The reconfiguration of the parallel manipulator is posed as a nonlinear optimization problem where the design variables correspond to the anchoring points of the limbs of the robot on the fixed platform. The penalty function minimizes the forces applied by the actuators during a specific trajectory. Some constraints are imposed to avoid forward singularities and guarantee the feasibility of the active generalized coordinates for a certain trajectory. The results are compared with different optimization approaches with the aim of avoiding getting trapped into a local minimum and undergoing forward singularities. The comparison covers evolutionary algorithms, heuristics optimizers, multistrategy algorithms, and gradient-based optimizers. The proposed methodology has been successfully tested on an actual parallel robot for different trajectories.This research was funded by the Spanish Ministry of Education, Culture and Sports, grant number DPI2017-84201-R.Llopis-Albert, C.; Valero Chuliá, FJ.; Mata Amela, V.; Pulloquinga-Zapata, J.; Zamora-Ortiz, P.; Escarabajal-Sánchez, RJ. (2020). Optimal Reconfiguration of a Parallel Robot for Forward Singularities Avoidance in Rehabilitation Therapies. A Comparison via Different Optimization Methods. Sustainability. 12(14):1-18. https://doi.org/10.3390/su12145803S1181214Rubio, F., Valero, F., & Llopis-Albert, C. (2019). A review of mobile robots: Concepts, methods, theoretical framework, and applications. International Journal of Advanced Robotic Systems, 16(2), 172988141983959. doi:10.1177/1729881419839596Jamwal, P. K., Xie, S. Q., Hussain, S., & Parsons, J. G. (2014). An Adaptive Wearable Parallel Robot for the Treatment of Ankle Injuries. IEEE/ASME Transactions on Mechatronics, 19(1), 64-75. doi:10.1109/tmech.2012.2219065Niu, X., Yang, C., Tian, B., Li, X., & Han, J. (2019). Modal Decoupled Dynamics Feed-Forward Active Force Control of Spatial Multi-DOF Parallel Robotic Manipulator. Mathematical Problems in Engineering, 2019, 1-13. doi:10.1155/2019/1835308Chablat, D., Kong, X., & Zhang, C. (2018). Kinematics, Workspace, and Singularity Analysis of a Parallel Robot With Five Operation Modes. Journal of Mechanisms and Robotics, 10(3). doi:10.1115/1.4039400Gao, Z., & Zhang, D. (2011). Workspace Representation and Optimization of a Novel Parallel Mechanism with Three-Degrees-of-Freedom. Sustainability, 3(11), 2217-2228. doi:10.3390/su3112217Hu, B., Shi, D., Xie, T., Hu, B., & Ye, N. (2020). Kinematically identical manipulators derivation for the 2-RPU+UPR parallel manipulator and their constraint performance comparison. Journal of Mechanisms and Robotics, 1-13. doi:10.1115/1.4047540Schappler, M., Tappe, S., & Ortmaier, T. (2019). Modeling Parallel Robot Kinematics for 3T2R and 3T3R Tasks Using Reciprocal Sets of Euler Angles. Robotics, 8(3), 68. doi:10.3390/robotics8030068Chen, Z., Xu, L., Zhang, W., & Li, Q. (2019). Closed-form dynamic modeling and performance analysis of an over-constrained 2PUR-PSR parallel manipulator with parasitic motions. Nonlinear Dynamics, 96(1), 517-534. doi:10.1007/s11071-019-04803-2Zhang, D., & Wei, B. (2017). Interactions and Optimizations Analysis between Stiffness and Workspace of 3-UPU Robotic Mechanism. Measurement Science Review, 17(2), 83-92. doi:10.1515/msr-2017-0011Wu, G., & Zou, P. (2016). Comparison of 3-DOF asymmetrical spherical parallel manipulators with respect to motion/force transmission and stiffness. Mechanism and Machine Theory, 105, 369-387. doi:10.1016/j.mechmachtheory.2016.07.017Meng, W., Xie, S. Q., Liu, Q., Lu, C. Z., & Ai, Q. (2017). Robust Iterative Feedback Tuning Control of a Compliant Rehabilitation Robot for Repetitive Ankle Training. IEEE/ASME Transactions on Mechatronics, 22(1), 173-184. doi:10.1109/tmech.2016.2618771Yang, Z., & Zhang, D. (2019). ENERGY OPTIMAL ADAPTION AND MOTION PLANNING OF A 3-RRS BALANCED MANIPULATOR. International Journal of Robotics and Automation, 34(5). doi:10.2316/j.2019.206-0171Zhang, D., & Gao, Z. (2012). Optimal Kinematic Calibration of Parallel Manipulators With Pseudoerror Theory and Cooperative Coevolutionary Network. IEEE Transactions on Industrial Electronics, 59(8), 3221-3231. doi:10.1109/tie.2011.2166229Lou, Y., Zhang, Y., Huang, R., Chen, X., & Li, Z. (2014). Optimization Algorithms for Kinematically Optimal Design of Parallel Manipulators. IEEE Transactions on Automation Science and Engineering, 11(2), 574-584. doi:10.1109/tase.2013.2259817Dumlu, A., & Erenturk, K. (2014). Trajectory Tracking Control for a 3-DOF Parallel Manipulator Using Fractional-Order $\hbox{PI}^{\lambda}\hbox{D}^{\mu}$ Control. IEEE Transactions on Industrial Electronics, 61(7), 3417-3426. doi:10.1109/tie.2013.2278964Llopis-Albert, C., Rubio, F., & Valero, F. (2018). Optimization approaches for robot trajectory planning. Multidisciplinary Journal for Education, Social and Technological Sciences, 5(1), 1. doi:10.4995/muse.2018.9867Gosselin, C., & Angeles, J. (1990). Singularity analysis of closed-loop kinematic chains. IEEE Transactions on Robotics and Automation, 6(3), 281-290. doi:10.1109/70.56660Briot, S., Arakelian, V., Bonev, I. A., Chablat, D., & Wenger, P. (2008). Self-Motions of General 3-RPR Planar Parallel Robots. The International Journal of Robotics Research, 27(7), 855-866. doi:10.1177/0278364908092466Karimi, A., Masouleh, M. T., & Cardou, P. (2016). Avoiding the singularities of 3-RPR parallel mechanisms via dimensional synthesis and self-reconfigurability. Mechanism and Machine Theory, 99, 189-206. doi:10.1016/j.mechmachtheory.2016.01.006Patel, Y. D., & George, P. M. (2012). Parallel Manipulators Applications—A Survey. Modern Mechanical Engineering, 02(03), 57-64. doi:10.4236/mme.2012.23008Araujo-Gómez, P., Díaz-Rodríguez, M., Mata, V., & González-Estrada, O. A. (2019). Kinematic analysis and dimensional optimization of a 2R2T parallel manipulator. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 41(10). doi:10.1007/s40430-019-1934-1Araujo-Gómez, P., Mata, V., Díaz-Rodríguez, M., Valera, A., & Page, A. (2017). Design and Kinematic Analysis of a Novel 3UPS/RPU Parallel Kinematic Mechanism With 2T2R Motion for Knee Diagnosis and Rehabilitation Tasks. Journal of Mechanisms and Robotics, 9(6). doi:10.1115/1.4037800Vallés, M., Araujo-Gómez, P., Mata, V., Valera, A., Díaz-Rodríguez, M., Page, Á., & Farhat, N. M. (2017). Mechatronic design, experimental setup, and control architecture design of a novel 4 DoF parallel manipulator. Mechanics Based Design of Structures and Machines, 46(4), 425-439. doi:10.1080/15397734.2017.1355249Koziel, S., & Yang, X.-S. (Eds.). (2011). Computational Optimization, Methods and Algorithms. Studies in Computational Intelligence. doi:10.1007/978-3-642-20859-1Beiranvand, V., Hare, W., & Lucet, Y. (2017). Best practices for comparing optimization algorithms. Optimization and Engineering, 18(4), 815-848. doi:10.1007/s11081-017-9366-1Page, A., De Rosario, H., Mata, V., Hoyos, J. V., & Porcar, R. (2006). Effect of marker cluster design on the accuracy of human movement analysis using stereophotogrammetry. Medical and Biological Engineering and Computing, 44(12), 1113-1119. doi:10.1007/s11517-006-0124-3Arora, J. S., Chahande, A. I., & Paeng, J. K. (1991). Multiplier methods for engineering optimization. International Journal for Numerical Methods in Engineering, 32(7), 1485-1525. doi:10.1002/nme.1620320706Modefrontier Toolhttps://www.esteco.com.202

Development of lower-limb rehabilitation exercises using 3-PRS Parallel Robot and Dynamic Movement Primitives

[EN] The design of rehabilitation exercises applied to sprained ankles requires extreme caution, regarding the trajectories and the speed of the movements that will affect the patient. This paper presents a technique that allows a 3-PRS parallel robot to control such exercises, consisting of dorsi/plantar flexion and inversion/eversion ankle movements. The work includes a position control scheme for the parallel robot in order to follow a reference trajectory for each limb with the possibility of stopping the exercise in mid-execution without control loss. This stop may be motivated by the forces that the robot applies to the patient, acting like an alarm mechanism. The procedure introduced here is based on Dynamic Movement Primitives (DMPs).This work has been partially funded by FEDER-CICYT project with reference DPI2017-84201-R financed by Ministerio de Economía, Industria e Innovación (Spain).Escarabajal Sánchez, RJ.; Abu Dakka, FJM.; Pulloquinga Zapata, J.; Mata Amela, V.; Vallés Miquel, M.; Valera Fernández, Á. (2020). Development of lower-limb rehabilitation exercises using 3-PRS Parallel Robot and Dynamic Movement Primitives. Multidisciplinary Journal for Education, Social and Technological Sciences. 7(2):30-44. https://doi.org/10.4995/muse.2020.13907OJS304472Abu-Dakka, F. J., Valera, A., Escalera, J. A., Vallés, M., Mata, V., & Abderrahim, M. (2015). Trajectory adaptation and learning for ankle rehabilitation using a 3-PRS parallel robot. Lecture Notes in Computer Science (Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 9245, 483-494. https://doi.org/10.1007/978-3-319-22876-1_41Atkeson, C. G., Moore, A. W., & Schaal, S. (1997). Locally Weighted Learning. Artificial Intelligence Review, 11(1-5), 11-73. https://doi.org/10.1007/978-94-017-2053-3_2Brockett, C. L., & Chapman, G. J. (2016). Biomechanics of the ankle. Orthopaedics and Trauma, 30(3), 232-238. https://doi.org/10.1016/j.mporth.2016.04.015Dai, J. S., Zhao, T., & Nester, C. (2004). Sprained Ankle Physiotherapy Based Mechanism Synthesis and Stiffness Analysis of a Robotic Rehabilitation Device. Autonomous Robots, 16(2), 207-218. https://doi.org/10.1023/B:AURO.0000016866.80026.d7Díaz-Rodríguez, M., Mata, V., Valera, Á., & Page, Á. (2010). A methodology for dynamic parameters identification of 3-DOF parallel robots in terms of relevant parameters. Mechanism and Machine Theory, 45(9), 1337-1356. https://doi.org/10.1016/j.mechmachtheory.2010.04.007Díaz, I., Gil, J. J., & Sánchez, E. (2011). Lower-Limb Robotic Rehabilitation: Literature Review and Challenges. Journal of Robotics, 2011(i), 1-11. https://doi.org/10.1155/2011/759764Fanger, Y., Umlauft, J., & Hirche, S. (2016). Gaussian Processes for Dynamic Movement Primitives with application in knowledge-based cooperation. IEEE International Conference on Intelligent Robots and Systems, 2016-Novem, 3913-3919. https://doi.org/10.1109/IROS.2016.7759576Gosselin, C., & Angeles, J. (1990). Singularity Analysis of Closed-Loop Kinematic Chains. IEEE Transactions on Robotics and Automation, 6(3), 281-290. https://doi.org/10.1109/70.56660Hesse, S., & Uhlenbrock, D. (2000). A mechanized gait trainer for restoration of gait. Journal of Rehabilitation Research and Development, 37(6), 701-708.Ijspeert, A. J., Nakanishi, J., Hoffmann, H., Pastor, P., & Schaal, S. (2013). Dynamical movement primitives: Learning attractor models formotor behaviors. Neural Computation, 25(2), 328-373. https://doi.org/10.1162/NECO_a_00393Ijspeert, A. J., Nakanishi, J., & Schaal, S. (2002). Movement imitation with nonlinear dynamical systems in humanoid robots. Proceedings - IEEE International Conference on Robotics and Automation, 2, 1398-1403. https://doi.org/10.1109/ROBOT.2002.1014739Liu, G., Gao, J., Yue, H., Zhang, X., & Lu, G. (2006). Design and kinematics simulation of parallel robots for ankle rehabilitation. 2006 IEEE International Conference on Mechatronics and Automation, ICMA 2006, 2006, 1109-1113. https://doi.org/10.1109/ICMA.2006.257780Nakanishi, J., Morimoto, J., Endo, G., Cheng, G., Schaal, S., & Kawato, M. (2004). Learning from demonstration and adaptation of biped locomotion. Robotics and Autonomous Systems, 47(2-3), 79-91. https://doi.org/10.1016/j.robot.2004.03.003Nemec, B., & Ude, A. (2012). Action sequencing using dynamic movement primitives. Robotica, 30(5), 837-846. https://doi.org/10.1017/S0263574711001056Patel, Y. D., & George, P. M. (2012). Parallel Manipulators Applications-A Survey. Modern Mechanical Engineering, 02(03), 57-64. https://doi.org/10.4236/mme.2012.23008Paul, R. P. (1981). Robot Manipulators: Mathematics, Programming, and Control : the Computer Control of Robot Manipulators (p. 279).Reinkensmeyer, D. J., Aoyagi, D., Emken, J. L., Galvez, J. A., Ichinose, W., Kerdanyan, G., Maneekobkunwong, S., Minakata, K., Nessler, J. A., Weber, R., Roy, R. R., De Leon, R., Bobrow, J. E., Harkema, S. J., & Reggie Edgerton, V. (2006). Tools for understanding and optimizing robotic gait training. Journal of Rehabilitation Research and Development, 43(5), 657-670. https://doi.org/10.1682/JRRD.2005.04.0073Safran, M. R., Benedetti, R. S., Bartolozzi, A. R., & Mandelbaum, B. R. (1999). Lateral ankle sprains: A comprehensive review part 1: Etiology, pathoanatomy, histopathogenesis, and diagnosis. In Medicine and Science in Sports and Exercise (Vol. 31, Issue 7 SUPPL., pp. S429-S437).https://doi.org/10.1097/00005768-199907001-00004Saglia, J. A., Tsagarakis, N. G., Dai, J. S., & Caldwell, D. G. (2013). Control strategies for patient-assisted training using the ankle rehabilitation robot (ARBOT). IEEE/ASME Transactions on Mechatronics, 18(6), 1799-1808. https://doi.org/10.1109/TMECH.2012.2214228Schaal, S. (2006). Dynamic Movement Primitives -A Framework for Motor Control in Humans and Humanoid Robotics. In Adaptive Motion of Animals and Machines (pp. 261-280). https://doi.org/10.1007/4-431-31381-8_23Sui, P., Yao, L., Lin, Z., Yan, H., & Dai, J. S. (2009). Analysis and synthesis of ankle motion and rehabilitation robots. 2009 IEEE International Conference on Robotics and Biomimetics, ROBIO 2009, 3, 2533-2538. https://doi.org/10.1109/ROBIO.2009.5420487Tsoi, Y. H., Xie, S. Q., & Graham, A. E. (2009). Design, modeling and control of an ankle rehabilitation robot. Studies in Computational Intelligence, 177, 377-399. https://doi.org/10.1007/978-3-540-89933-4_18Vallés, M., Díaz-Rodrguez, M., Valera, Á., Mata, V., & Page, Á. (2012). Mechatronic development and dynamic control of a 3-dof parallel manipulator. Mechanics Based Design of Structures and Machines, 40(4), 434-452. https://doi.org/10.1080/15397734.2012.687292Xie, S. (2016). Advanced robotics for medical rehabilitation: current state of the art and recent advances. In Springer tracts in advanced robotics (Issue 108). https://doi.org/10.1007/978-3-319-19896-5Yoon, J., Ryu, J., & Lim, K. B. (2006). Reconfigurable ankle rehabilitation robot for various exercises. Journal of Robotic Systems, 22(SUPPL.), 15-33. https://doi.org/10.1002/rob.2015

Combined Admittance Control With Type II Singularity Evasion for Parallel Robots Using Dynamic Movement Primitives

[EN] This article addresses a new way of generating compliant trajectories for control using movement primitives to allow physical human-robot interaction where parallel robots (PRs) are involved. PRs are suitable for tasks requiring precision and performance because of their robust behavior. However, two fundamental issues must be resolved to ensure safe operation: first, the force exerted on the human must be controlled and limited, and second, Type II singularities should be avoided to keep complete control of the robot. We offer a unified solution under the dynamic movement primitives (DMP) framework to tackle both tasks simultaneously. DMPs are used to get an abstract representation for movement generation and are involved in broad areas, such as imitation learning and movement recognition. For force control, we design an admittance controller intrinsically defined within the DMP structure, and subsequently, the Type II singularity evasion layer is added to the system. Both the admittance controller and the evader exploit the dynamic behavior of the DMP and its properties related to invariance and temporal coupling, and the whole system is deployed in a real PR meant for knee rehabilitation. The results show the capability of the system to perform safe rehabilitation exercises.This work was supported in part by the Fondo Europeo de Desarrollo Regional under Grant PID2021-125694OB-I00, in part by the Vicerrectorado de Investigacion de la Universitat Politecnica de Valencia under Grant PAID-11-21, and in part by the Ministerio de Universidades, Gobierno de Espana under Grant FPU18/05105.Escarabajal-Sánchez, RJ.; Pulloquinga-Zapata, J.; Valera Fernández, Á.; Mata Amela, V.; Vallés Miquel, M.; Castillo-García, FJ. (2023). Combined Admittance Control With Type II Singularity Evasion for Parallel Robots Using Dynamic Movement Primitives. IEEE Transactions on Robotics. 39(3):2224-2239. https://doi.org/10.1109/TRO.2023.32381362224223939

Desarrollo de un juego de ajedrez automatizado mediante robot cartesiano y Raspberry PI

[ES] El desarrollo del presente trabajo persigue la obtención de un sistema con distintas capacidades que permita la ejecución de partidas de ajedrez en tiempo real con diversas modalidades y, por tanto, con diferentes aplicaciones que pueden ser empleadas en ámbitos variopintos. Para tal ejercicio se cuenta, como elementos primordiales, con una Raspberry Pi y un robot cartesiano que sobre un tablero real realiza el movimiento automático de las piezas. En los sucesivos documentos que conforman este escrito, se aclara hasta qué punto son conseguidos los objetivos planteados y cómo se han desarrollado las distintas bases armónicamente coordinadas que componen dicho sistema, que resumidamente son: • Diseño de una serie de algoritmos para el control de los movimientos realizados, eludiendo a toda costa la ejecución de jugadas imposibles por parte de alguno de los jugadores, así como la asignación estricta del turno de juego para evitar movimientos consecutivos realizados por el mismo jugador, lo que alteraría drásticamente el curso normal de la partida. • Posibilidad de jugar contra un motor de ajedrez, aceptando la participación de un único jugador dispuesto a ponerse a prueba. • Automatización de las distintas jugadas sobre un tablero, eximiendo al jugador de la obligatoriedad habitual de personarse en una partida cuando se realiza físicamente. • Desarrollo de sendas aplicaciones de móvil y web para jugar remotamente, la primera basada en un sistema de sonidos especialmente diseñada para invidentes y la segunda para poder interactuar desde un navegador web. Estas aplicaciones se conjugan con la ejecución física y automática de la jugada, aportándole más sentido. • Diseño gráfico de los distintos elementos que los usuarios pueden visualizar en sus respectivas interfaces para el desarrollo cómodo de la partida, así como la comunicación entre ellos. En lo que concierne al software, el lenguaje de programación empleado por excelencia ha sido Python, excepto en aquellas aplicaciones externas a la Raspberry Pi, optando por Android para el móvil y HTML para la página web.Escarabajal Sánchez, RJ. (2017). Desarrollo de un juego de ajedrez automatizado mediante robot cartesiano y Raspberry PI. http://hdl.handle.net/10251/87395.TFG

Diseño de un sistema para monitorización y predicción de fallos de procesos industriales basado en una plataforma cloud y técnicas de Machine Learning

[ES] El objetivo general del proyecto es el diseño e implementación de un sistema inteligente para la detección de fallos en procesos industriales utilizando una tecnología emergente en la denominada Industria 4.0 como es el análisis y procesamiento de datos en la nube (o cloud). En el proyecto se diseñará y programará la arquitectura de comunicaciones industriales basada en protocolos Mobus-TCP y OPC-UA para comunicar una serie de PLCs con dos concentradores de datos (datahubs). Más tarde se diseñará y programará la plataforma de comunicaciones hacia la nube, basada en protocolos ioT como MQTT y servicios web (REST-API). Tras el diseño del sistema de transferencia de datos hacia/desde la nube, se implementarán algunas estrategias de detección de fallos basadas en técnicas de inteligencia artificial (como redes neuronales, o algoritmos basados en distribuciones gaussianas). Como interfaz se diseñará una plataforma web con JavaScript para poder operar de forma remota todo el sistema de monitorización incluyendo una aplicación para dispositivos móviles. Para la implementación de todo lo anterior se usarán el material del laboratorio de Automatización del DISA (PLCs de Omron, Siemens y Schneider, Raspberry Pi y plataforma cloud Thingspeak de Mathworks).Escarabajal Sánchez, RJ. (2019). Diseño de un sistema para monitorización y predicción de fallos de procesos industriales basado en una plataforma cloud y técnicas de Machine Learning. http://hdl.handle.net/10251/129717TFG

A Type II singularity avoidance algorithm for parallel manipulators using output twist screws

[EN] Parallel robots (PRs) are closed-chain manipulators with diverse applications due to their accuracy and high payload. However, there are configurations within the workspace named Type II singularities where the PRs lose control of the end-effector movements. Type II singularities are a problem for applications where complete control of the end-effector is essential. Trajectory planning produces accurate movements of a PR by avoiding Type II singularities. Generally, singularity avoidance is achieved by optimising a geometrical path with a velocity profile considering singular configurations as obstacles. This research presents an algorithm that avoids Type II singularities by modifying the trajectory of a subset of the actuators. The subset of actuators represents the limbs responsible for a Type II singularity, and they are identified by the angle between two Output Twist Screws. The proposed avoidance algorithm does not require optimisation procedures, which reduces the computational cost for offline trajectory planning and makes it suitable for online trajectory planning. The avoidance algorithm is implemented in offline trajectory planning for a pick and place planar PR and a spatial knee rehabilitation PR.Acknowledgements This research was partially funded by Fondo Europeo de Desarrollo Regional (PID2021-125694OB-I00) , cofounded by Vicer-rectorado de Investigacion de la Universitat Politecnica de Valencia (PAID-11-21) and by Programa de Ayudas de Investigacion y Desarrollo de la Universitat Politecnica de Valencia (PAID-01-19) . Funding for open access charge: CRUE-Universitat Politecnica de Valencia. Moreover, the authors would like to thank the help of all anonymous reviewers, which have improved the paper's readability.Pulloquinga-Zapata, J.; Escarabajal-Sánchez, RJ.; Valera Fernández, Á.; Vallés Miquel, M.; Mata Amela, V. (2023). A Type II singularity avoidance algorithm for parallel manipulators using output twist screws. Mechanism and Machine Theory. 183:1-16. https://doi.org/10.1016/j.mechmachtheory.2023.10528211618

Admittance controller complemented with real-time singularity avoidance for rehabilitation parallel robots

[EN] Rehabilitation tasks demand robust and accurate trajectory-tracking performance, mainly achieved with parallel robots. In this field, limiting the value of the force exerted on the patient is crucial, especially when an injured limb is involved. In human-robot interaction studies, the admittance controller modifies the location of the robot according to the user efforts driving the end-effector to an arbitrary location within the workspace. However, a parallel robot has singularities within the workspace, making implementing a conventional admittance controller unsafe. Thus, this study proposes an admittance controller that overcomes the limitations of singular configurations by using a real-time singularity avoidance algorithm. The singularity avoidance algorithm modifies the original trajectory based on the actual location of the parallel robot. The complemented admittance controller is applied to a 4 degrees of freedom parallel robot for knee rehabilitation. In this case, the actual location is measured by a 3D tracking system because the location calculated by the forward kinematics is inaccurate in the vicinity of a singularity. The experimental results verify the effectiveness of the proposed admittance controller for safe knee rehabilitation exercises.Acknowledgements This research was partially funded by Fondo Europeo de Desarrollo Regional (PID2021-125694OB-I00), cofounded by Programa de Ayudas de Investigacion y Desarrollo de la Universitat Politecnica de Valencia (PAID-01-19). Funding for open access charge: CRUE-Universitat Politecnica de Valencia.Pulloquinga-Zapata, JL.; Escarabajal-Sánchez, RJ.; Vallés Miquel, M.; Díaz-Rodríguez, M.; Mata Amela, V.; Valera Fernández, Á. (2023). Admittance controller complemented with real-time singularity avoidance for rehabilitation parallel robots. Mechatronics. 94:1-12. https://doi.org/10.1016/j.mechatronics.2023.1030171129