Open Access
Characterization and optimization of cutting depth in passive-compliant robotic belt grinding
(Springer, 2024-12-30) Torres Izu, Ramón; Aginaga García, Jokin; Mata Cantón, Sara; Barrenetxea Azpeitia, David; Inziarte Hidalgo, Ibai; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Robotic belt grinding offers numerous advantages, such as operational versatility and the ability to work in complex spaces. Its implementation in the modern industry aims to surpass manual grinding tasks and enhance overall productivity. Among these processes, compliant techniques offer adaptive solutions, where the tool can adapt to complex surfaces, besides providing more efficient grinding solutions for industrial applications. This paper focuses on an easy characterization of the cutting depth in a robotic belt grinding application using a portable passive-compliant tool. To this end, a cutting depth belt grinding model based on process parameters is presented. Experimental tests are conducted to correlate the depth of material removal with the belt wear behavior and analysis on Inconel 718 specimens. Then, the solution presented is validated through additional tests. Furthermore, the model is utilized for a productivity optimization that takes into account the belt wear, searching for optimal process variables that minimize cycle time.
Open Access
AI training for application to industrial robotics: trajectory generation for neural network tuning
(Springer, 2023) Merino Olagüe, Mikel; Ibarrola Chamizo, Javier; Aginaga García, Jokin; Hualde Otamendi, Mikel; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
In the present work robot trajectories are generated and kinematically simulated. Different data (joint coordinates, end effector position and orientation, images, etc.) are obtained in order to train a neural network suited for applications in robotics. The neural network has the goal of automatically generating trajectories based on a set of images and coordinates. For this purpose, trajectories are designed in two separate sections which are conveniently connected using Bezier curves, ensuring continuity up to accelerations. In addition, among the possible trajectories that can be carried out due to the different configurations of the robot, the most suitable ones have been selected avoiding collisions and singularities. The designed algorithm can be used in multiple applications by adapting its different parameters.
Open Access
4P operational harmonic and blade vibration in wind turbines: a real case study of an active yaw system and a concrete tower
(Elsevier, 2024) Torres Elizondo, Antonio; Gil Soto, Javier; Plaza Puértolas, Aitor; Aginaga García, Jokin; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This study aims to comprehensively investigate the impact of mechanical loads on the performance and lifetime of wind turbines, with particular emphasis on blade vibration at the 4P operational harmonic. Experiments and advanced aeroelastic simulations are combined to assess how active yaw systems and concrete towers affect this specific vibration. Contrary to previous assumptions, field tests have shown that there is a resonance phenomenon in the blade. Specifically, the first edgewise mode of the blade resonates at the 4P frequency, which did not happen in the aeroelastic simulations. Remarkably, thorough aeroelastic simulations show that this resonance is triggered by the excitation of the Edgewise Backward Whirling mode of the rotor, which occurs at the 3P operating harmonic. This study highlights the need for accurate and precise modelling using aeroelastic simulations to reproduce the resonance phenomenon and analyse the contributing factors. A major breakthrough is the discovery that stiffening the active yaw system significantly reduces the 3P hub fixed motions, resulting in reduced blade vibration at the 4P frequency. Furthermore, the simulations show the sensitivity of the 4P vibration to different wind characteristics, providing valuable insights for the design of wind turbines in different environmental conditions.
Open Access
Exploring the impact of social relationship modification on young female soccer players' performance in small-sided games
(Termedia, 2024-12-06) Los Arcos Larumbe, Asier; González-Artetxe, Asier; Lombardero, Sara; Esnal-Arrizabalaga, Oihan; Aginaga García, Jokin; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
This study compared young female soccer players' tactical, conditional, and emotional responses during two small-sided games (SSGs), without restrictions (SSGfree), and introducing an additional rule (SSGrelationship: if a player touches an opponent just before she receives the ball, her team wins the ball back with an indirect free kick). Fourteen developmental U14 players participated in two 4 × 6-min seven-a-side games (six each, plus goalkeepers) on a 50-m long × 30-m wide field. Players' positional data were collected using a GPS to assess their tactical performance (central tendency and entropy measures of the surface area, distance between players and to the nearest opponent, and stretch and spatial exploration indices) and conditional performance (total and low-moderate, high, very high speed, sprinting distance covered, and the number of accelerations and decelerations). Participants also rated their perceived enjoyment and competence using the BECS scale. Tactical central tendency measures were higher during SSGfree (p < 0.05) than in SSGrelationship, but no differences were apparent for entropy and conditional measures (p > 0.05). From bout to bout, central tendency measures of tactical variables decreased more frequently during SSGfree than SSGrelationship. Entropy measures and conditional performance hardly varied between bouts. Enjoyment and perceived competence levels were similar for both SSGs. The findings indicate that modifying the interaction between opponents affects players' tactical responses more than conditional responses when compared with free play. Specifically, touching an opponent before they receive the ball may encourage players to play closer to their opponents during training tasks.
Open Access
A unified analytical disk cam profile generation methodology using the Instantaneous Center of Rotation for educational purpose
(Elsevier, 2024) Iriarte Goñi, Xabier; Bacaicoa Díaz, Julen; Plaza Puértolas, Aitor; Aginaga García, Jokin; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Cam design is a fundamental part of the Mechanism and Machine Theory (MMT) and is included in the vast majority of MMT books. Cam profile design is usually determined with graphical and analytical methods. Graphical methods are didactically very successful to introduce the theory of cam profile generation in a simple way. In turn, analytical methods allow computer implementations of cam profile generation in order to reproduce it accurately. Most modern MMT books describe analytical methods using geometric equations and envelope theory. However, the analytical profile definition depends on the specific type of follower and there is a lack of a general formulation. This work presents a unified and general analytical formulation for the disk cam profile determination. Based on the Instantaneous Center of Rotation and the kinematic inversion, the formulation provides analytical expressions of the cam profile and is applicable to any type of follower. Thus, the unified formulation can be used in forthcoming books on this discipline.
Open Access
Inertia transfer concept based general method for the determination of the base inertial parameters
(Springer, 2015) Ros Ganuza, Javier; Plaza Puértolas, Aitor; Iriarte Goñi, Xabier; Aginaga García, Jokin; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
This paper presents a new algorithm to obtain the symbolic expressions of any of the possible base inertial parameter sets of a multibody system. Based on the ¿inertia transfer concept¿, a procedure is proposed to write a system of equations from which the base parameters are obtained. This leads to an automatizable and general method to obtain these parameters symbolically. The method can also be used to determine base inertial parameters numerically, and it can be even more straightforward to implement and use than the standard numerical methods. An example is presented to illustrate in detail the application of the algorithm, and to compare its results with those of a standard numerical procedure. The symbolic base inertial parameters can be of interest in symbolic simplification of the dynamic equations for real-time applications, design optimization, dynamic parameter identification, model reduction, and in other fields.
Open Access
Comprehensive analysis of rotor edgewise whirling mode interaction with rotor speed harmonics
(IOP Publishing, 2024) Torres Elizondo, Antonio; Gil Soto, Javier; Plaza Puértolas, Aitor; Aginaga García, Jokin; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
This paper presents a model that investigates the interaction between rotor edgewise whirling modes and rotor speed harmonics in wind turbines. The model is based on kinematic and dynamic principles, with a focus on the multi-blade coordinate transformation, which is critical for simulating the behaviour of the rotor whirling modes in wind turbines. The research has two objectives: to investigate the interaction between the rotor edgewise whirling modes and the rotor speed harmonics, and to provide clearer graphs that explain the complex nature of this non-intuitive rotor dynamics. The paper concludes by highlighting the practical implications of the research findings, in particular the effectiveness of visualisation techniques in identifying and explaining unexpected interactions.
Open Access
Trayectorias de máxima rigidez de un robot redundante actuando como soporte en el mecanizado de paredes delgadas
(Universitat Politècnica de València, 2023) Aginaga García, Jokin; García Cuesta, Iván; Iriarte Goñi, Xabier; Plaza Puértolas, Aitor; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
La precisión de un robot está ligada a su rigidez. En comparación con la máquina herramienta tradicional, los robots industriales tienen un gran espacio de trabajo como ventaja, pero una rigidez reducida como desventaja. Además, la rigidez tiene una gran dependencia y variabilidad con la postura o configuración del robot. De ahí que resulte necesario un análisis de rigidez de los robots, que se evalúa mediante la matriz de rigidez. En este trabajo se presenta un análisis de rigidez de un robot serie. Ante la diversidad de índices representativos extraídos a partir de la matriz de rigidez, se ha propuesto el uso de un índice que tenga en cuenta la dirección de las cargas que soporta el robot y la dirección en que se desea que el robot aporte rigidez en la aplicación específica. Asimismo, se ha utilizado el índice de rigidez para llevar el robot a configuraciones que mejoren la rigidez, hecho que resulta posible en aplicaciones en las que el robot tiene al menos un grado de libertad (GDL) redundante. La metodología se ha aplicado a un robot de 7 GDL utilizado como robot de soporte en el mecanizado de paredes delgadas. Dado que para definir la trayectoria únicamente son necesarios 5 GDL, se utilizan 2 GDL reduntantes para mejorar la rigidez.
Open Access
Effects of playing football matches with two balls on spatial exploration: average and one-by-one analyses
(Palacký University in Olomouc, 2024-07-02) González-Artetxe, Asier; Los Arcos Larumbe, Asier; Aginaga García, Jokin; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
Background: football task design lies in manipulating the relevant features of the game considering the consequences these modifications can have on players' performance. Adding an extra ball may boost academy footballers' possibilities of interaction and challenge them to readjust their motor conduct according to the uncertainty of a novel game scenario. Objective: this study compared young footballers¿ spatial exploration index (SEI) overall and one by one during simulated matches played with one or two balls. Methods: forty-four association football players from U14 and U16 teams of the same club played two 60-minute matches with all the official game rules and regulatory conditions. The unique difference was that one match was played with a single ball and the other with two balls simultaneously. Positional data were gathered during matches using a Global Positioning System (GPS) to assess each footballer's SEI central tendency and approximate entropy (ApEn) measures. Results: the average SEI of both U14 (p = .01; -2 = .066, medium) and U16 (p < .001; -2 = .187, large) players was lower, and its ApEn higher (U14: p < .001, -2 = .014, small; U16: p < .001, -2 = .035, small), during the two-ball match in comparison to the standard one-ball match. The graphical representation shows how their relative positioning changed between matches, breaking team formation in two during the two-ball condition. From an individual perspective, the second ball affected defenders mainly. Most of them reduced their intervention area, acted more unpredictably within this, and got closer to their target compared with the standard one-ball match. Conclusions: adding an extra ball led young footballers to explore less space more unpredictably, especially defenders. So, a one-by-one analysis may assist coaches in evaluating each player¿s tactical response to football training.
Open Access
Optimal strain gauge configurations for the estimation of mechanical loads in the main shaft of HAWT
(IOP Publishing, 2020) Iriarte Goñi, Xabier; Aginaga García, Jokin; Lerga Valencia, Francisco Javier; Gainza González, Gorka; Ros Ganuza, Javier; Bacaicoa Díaz, Julen; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería
In Structural Health Monitoring of wind turbines, measuring the mechanical loads is a key issue. The customary techniques for this task use a full-bridge strain gauge configuration to measure each of the six load components exerted on the shaft. However, using only six strain gauges should be sufficient to estimate the six load components if a one-to-one correspondence was achieved. In this paper a different approach to mechanical loads estimation is presented where, measuring the strain of individual gauges in quarter-bridge configurations, it is possible to estimate all the load components from a single set of gauges. The configurations are optimally determined making use of the D-optimality criterion, which maximises the observability of the estimated components. The approach also provides configurations where the apparent strain related to temperature variations is automatically compensated. Results show several optimal configurations for different measuring conditions and shows that six strain gauges are enough to estimate all the load components. The new approach also opens the possibility to obtain configurations with more strain gauges as well as configurations that have to meet other requirements.