Force Control Improvement in Collaborative Robots through Theory Analysis and Experimental Endorsement

[EN] Due to the elasticity of their joints, collaborative robots are seldom used in applications with force control. Besides, the industrial robot controllers are closed and do not allow the user to access the motor torques and other parameters, hindering the possibility of carrying out a customized control. A good alternative to achieve a custom force control is sending the output of the force regulator to the robot controller through motion commands (inner/outer loop control). There are different types of motion commands (e.g., position or velocity). They may be implemented in different ways (Jacobian inverse vs. Jacobian transpose), but this information is usually not available for the user. This article is dedicated to the analysis of the effect of different inner loops and their combination with several external controllers. Two of the most determinant factors found are the type of the inner loop and the stiffness matrix. The theoretical deductions have been experimentally verified on a collaborative robot UR3, allowing us to choose the best behaviour in a polishing operation according to pre-established criteria.The authors are grateful for the financial support of the Spanish Ministry of Economy and European Union, grant DPI2016-81002-R (AEI/FEDER, UE), to the research work here published. Rodrigo Perez-Ubeda is grateful to the Ph.D. Grant CONICYT PFCHA/DOCTORADO BECAS CHILE/2017-72180157.Pérez-Ubeda, R.; Zotovic Stanisic, R.; Gutiérrez, SC. (2020). Force Control Improvement in Collaborative Robots through Theory Analysis and Experimental Endorsement. Applied Sciences. 10(12):1-24. https://doi.org/10.3390/app10124329S1241012Top Trends Robotics 2020—International Federation of Robotics https://ifr.org/ifr-press-releases/news/top-trends-robotics-2020Gaz, C., Magrini, E., & De Luca, A. (2018). A model-based residual approach for human-robot collaboration during manual polishing operations. 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Choosing Poses for Force and Stiffness Control. IEEE Transactions on Robotics, 33(6), 1483-1490. doi:10.1109/tro.2017.2708087Magrini, E., & De Luca, A. (2016). Hybrid force/velocity control for physical human-robot collaboration tasks. 2016 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS). doi:10.1109/iros.2016.7759151Ahmad, S. (1993). Constrained motion (force/position) control of flexible joint robots. IEEE Transactions on Systems, Man, and Cybernetics, 23(2), 374-381. doi:10.1109/21.229451Calanca, A., & Fiorini, P. (2018). Understanding Environment-Adaptive Force Control of Series Elastic Actuators. IEEE/ASME Transactions on Mechatronics, 23(1), 413-423. doi:10.1109/tmech.2018.2790350Oh, S., & Kong, K. (2017). High-Precision Robust Force Control of a Series Elastic Actuator. IEEE/ASME Transactions on Mechatronics, 22(1), 71-80. doi:10.1109/tmech.2016.2614503Yin, H., Li, S., & Wang, H. (2016). 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Explicit and implicit force control of an industrial manipulator — An experimental summary. 2016 21st International Conference on Methods and Models in Automation and Robotics (MMAR). doi:10.1109/mmar.2016.7575081Neranon, P., & Bicker, R. (2016). Force/position control of a robot manipulator for human-robot interaction. Thermal Science, 20(suppl. 2), 537-548. doi:10.2298/tsci151005036nChen, S., Zhang, T., & Zou, Y. (2017). Fuzzy-Sliding Mode Force Control Research on Robotic Machining. Journal of Robotics, 2017, 1-8. doi:10.1155/2017/8128479Lin, H.-I., & Dubey, V. (2018). Design of an Adaptive Force Controlled Robotic Polishing System Using Adaptive Fuzzy-PID. Advances in Intelligent Systems and Computing, 825-836. doi:10.1007/978-3-030-01370-7_64Perez-Vidal, C., Gracia, L., Sanchez-Caballero, S., Solanes, J. E., Saccon, A., & Tornero, J. (2019). Design of a polishing tool for collaborative robotics using minimum viable product approach. International Journal of Computer Integrated Manufacturing, 32(9), 848-857. doi:10.1080/0951192x.2019.1637026Chen, F., Zhao, H., Li, D., Chen, L., Tan, C., & Ding, H. (2019). Contact force control and vibration suppression in robotic polishing with a smart end effector. Robotics and Computer-Integrated Manufacturing, 57, 391-403. doi:10.1016/j.rcim.2018.12.019Mohammad, A. E. K., Hong, J., & Wang, D. (2018). Design of a force-controlled end-effector with low-inertia effect for robotic polishing using macro-mini robot approach. Robotics and Computer-Integrated Manufacturing, 49, 54-65. doi:10.1016/j.rcim.2017.05.011Xiao, C., Wang, Q., Zhou, X., Xu, Z., Lao, X., & Chen, Y. (2019). Hybrid Force/Position Control Strategy for Electromagnetic based Robotic Polishing Systems. 2019 Chinese Control Conference (CCC). doi:10.23919/chicc.2019.8865183Li, J., Zhang, T., Liu, X., Guan, Y., & Wang, D. (2018). A Survey of Robotic Polishing. 2018 IEEE International Conference on Robotics and Biomimetics (ROBIO). doi:10.1109/robio.2018.8664890Zollo, L., Siciliano, B., De Luca, A., Guglielmelli, E., & Dario, P. (2004). Compliance Control for an Anthropomorphic Robot with Elastic Joints: Theory and Experiments. Journal of Dynamic Systems, Measurement, and Control, 127(3), 321-328. doi:10.1115/1.1978911Han, D., Duan, X., Li, M., Cui, T., Ma, A., & Ma, X. (2017). Interaction Control for Manipulator with compliant end-effector based on hybrid position-force control. 2017 IEEE International Conference on Mechatronics and Automation (ICMA). doi:10.1109/icma.2017.8015929Schindlbeck, C., & Haddadin, S. (2015). Unified passivity-based Cartesian force/impedance control for rigid and flexible joint robots via task-energy tanks. 2015 IEEE International Conference on Robotics and Automation (ICRA). doi:10.1109/icra.2015.7139036Zotovic Stanisic, R., & Valera Fernández, Á. (2009). 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The International Journal of Robotics Research, 19(9), 835-847. doi:10.1177/02783640022067201Institute of Robotics and Mechatronics DLR Light Weight Robot III https://www.dlr.de/rm/en/desktopdefault.aspx/tabid-12464/#gallery/2916

Behavioural Study of the Force Control Loop Used in a Collaborative Robot for Sanding Materials

[EN] The rise of collaborative robots urges the consideration of them for different industrial tasks such as sanding. In this context, the purpose of this article is to demonstrate the feasibility of using collaborative robots in processing operations, such as orbital sanding. For the demonstration, the tools and working conditions have been adjusted to the capacity of the robot. Materials with different characteristics have been selected, such as aluminium, steel, brass, wood, and plastic. An inner/outer control loop strategy has been used, complementing the robot¿s motion control with an outer force control loop. After carrying out an explanatory design of experiments, it was observed that it is possible to perform the operation in all materials, without destabilising the control, with a mean force error of 0.32%. Compared with industrial robots, collaborative ones can perform the same sanding task with similar results. An important outcome is that unlike what might be thought, an increase in the applied force does not guarantee a better finish. In fact, an increase in the feed rate does not produce significant variation in the finish¿less than 0.02 m; therefore, the process is in a ¿saturation state¿ and it is possible to increase the feed rate to increase productivity.Rodrigo Perez-Ubeda is grateful to the Ph.D. Grant CONICYT PFCHA/Doctorado Becas Chile/2017-72180157 and the University of Antofagasta, Chile.Pérez Ubeda, R.; Gutiérrez, SC.; Zotovic Stanisic, R.; Perles, A. (2020). Behavioural Study of the Force Control Loop Used in a Collaborative Robot for Sanding Materials. Materials. 14(1):1-19. https://doi.org/10.3390/ma14010067S11914

Tratamiento de fracturas de húmero proximal en hueso osteoporótico mediante fijación con sistema de aumentación

Introducción. Para el tratamiento de fracturas de húmero proximal en pacientes osteoporóticos, se han desarrollado fijaciones con aumentación que mejoran la estabilidad del implante. El objetivo de este estudio es analizar los resultados obtenidos con la técnica empleada. Material y métodos. Estudio descriptivo retrospectivo de 7 pacientes con fracturas en 3-4 fragmentos intervenidos mediante placa Philos (Synthes)® de aumentación. Seguimiento medio de 12 meses. Resultados. La puntuación media en la Escala Visual Analógica de dolor fue de 4,4. En la escala Quick Dash de 47,47. En la Escala Constant-Murley de 36,36. La abducción activa media fue de 95º; la flexión anterior media de 105º; la rotación externa media de 44,14º; la rotación interna alcanzó en tres pacientes S1, en dos L5, en uno L2 y en otro T10. En los controles radiográficos se mantuvo la reducción. Nos encontramos con un caso de consolidación parcial. Conclusión. Las técnicas de aumentación disminuyen el riesgo de fallos de fijación manteniendo la reducción.. Introduction. To treat proximal humerus fractures in patients with osteoporosis, the last few years, systems to improve implant stability by augmentation techniques have been developed. The aim of this study is to analyze the results obtained with the surgical technique employed. Materials and methods. Retrospective descriptive study. We selected 7 patients with 3 or 4- part fractures treated operatively with Philos Augmentation plate (Synthes)® fixation technique. Average follow-up was 12 months. Results. Pain measured with a Visual Analogical Scale (VAS) got a average value of 4,4. The mean Quick Dash Score was 47,47. The mean Constat-Murley modified was 36,36. The active articular balances showed a mean abduction of 91º; mean anterior flexion of 105º; mean external rotation of 44,14º; and finally the internal rotation achieved in three patients got to S1, in two patients to L5, in one patient to L2 and in other patient to T10. In X- Ray post-operative controls we can appreciate the reduction maintenance. In one case we observe a partial consolidation of the fracture. Conclusion. Surgical techniques that imply implant augmentation reduces the risk of implant failure and maintains the fracture reduction

Manejo de la infección protésica de hombro con gran defecto óseo: descripción de un caso complejo

La infección periprotésica de hombro tiene una incidencia de entre el 0.4% al 2.9%; su tratamiento es controvertido y se basa en la experiencia sobre infecciones protésicas de rodilla y cadera. Presentamos el caso de una paciente quien fue tratada mediante recambio en dos tiempos, la cual presentó como complicación añadida un gran defecto óseo metafisodiafisario tratado siguiendo pautas establecidas en la literatura actual, con buen resultado final, valorando aspectos analíticos, radiológicos y clínicosShoulder periprosthetic infection has an incidence of 0.4% to 2.9%; treatment is controversial and is based on the experience of prosthetic hip and knee infections. We report a patient who was treated by two-stage exchange, which added complication presented as a large bone defect treated following guidelines established in the current literature, with good outcome, evaluating blood analysis, radiological and clinical aspects

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El presente trabajo de investigación tiene como propósito principal realizar una comparación del movimiento de alcance entre sujetos aquejados de Daño Cerebral Adquirido y el correspondiente patrón de normalidad. La finalidad de esta comparación es detectar los déficits motores que permitan posteriormente emitir una valoración funcional del movimiento como parte de un método de evaluación objetiva de la función motora. La comparación del movimiento se basa en las medidas de parámetros espaciales y de similitud. En este trabajo se han utilizado modelos de movimiento de sujetos sanos en ejecuciones de Actividades de Vida Diaria (e.g. 'servir agua de una jarra'), como punto de referencia para encontrar diferencias relevantes con respecto a los datos de movimiento de cuatro pacientes bajo un proceso de Neurorrehabilitación Funcional de Extremidad Superi

Osificación Heterotópica Coxofemoral secundaria a Encefalitis Herpética : a propósito de un caso y revisión de la literatura

Heterotopic ossification is the abnormal formation of bone in soft tissues outside the skeleton. It is associated with nervous system injuries or after a hip replacement. It is therefore a relevant pathology against which there is a controversial diagnostic and therapeutic attitude. We report a case of a patient of 36 year who developed heterotopic ossification after herpetic encephalitis. We also review the published studies collecting the current recommendations for diagnosis, prevention and treatment

Artritis séptica por streptococcus pneumoniae: reporte de un caso

La artritis neumocócica es infrecuente en adultos, predomina en pacientes pediátricos. La neumonía y la bacteriemia son las manifestaciones más frecuentes, la afectación articular según series recientes tiene una prevalencia menor al 1% en sujetos menores de 50 años. Se presenta el caso de una paciente de 60 años con LES (Lupus Eritematoso Sistémico) la cual presentó monoartritis séptica de rodilla derecha causada por Streptococcus pneumoniaePneumococcal arthritis is uncommon in adults, predominantly in pediatric patients. Pneumonia and bacteremia are the most common manifestations; joint involvement according to recent series has a lower prevalence of 1% in subjects under 50 years. We report the case of a patient of 60 years with SLE (systemic lupus erythematosus) which presented septic monoarthritis right knee caused by Streptococcus pneumoniae

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