Articles de revistahttp://hdl.handle.net/2117/38992024-03-29T02:05:10Z2024-03-29T02:05:10ZMinimizing residual vibrations for non-zero initial states: Application to an emergency stop of a craneVeciana Fontanet, Joaquim MariaCardona Foix, SalvadorCatalà Calderon, Pauhttp://hdl.handle.net/2117/3359502021-09-19T10:03:48Z2021-01-25T15:11:59ZMinimizing residual vibrations for non-zero initial states: Application to an emergency stop of a crane
Veciana Fontanet, Joaquim Maria; Cardona Foix, Salvador; Català Calderon, Pau
This paper presents an approach to design command inputs for the reduction of residual vibrations in mechanical systems for nonzero initial states. The technique starts with the development of a standard input shaper in a second order oscillator, and adds the initial states of the system to the formulation. However, it is proven that the obtained input shaper does not guarantee a null residual vibration when it is convolved with any unshaped command. To obtain an analytically proven zero-vibration response, it is required to include the parameters that characterize the response of the system to a selected normalized unshaped command in the formulation. By introducing an appropriate processing time delay and by measuring the initial states using a feedback sensor, the proposed method has been applied in a real time scenario where an emergency stop of a crane is required, assuming that initially the payload is swaying.
2021-01-25T15:11:59ZVeciana Fontanet, Joaquim MariaCardona Foix, SalvadorCatalà Calderon, PauThis paper presents an approach to design command inputs for the reduction of residual vibrations in mechanical systems for nonzero initial states. The technique starts with the development of a standard input shaper in a second order oscillator, and adds the initial states of the system to the formulation. However, it is proven that the obtained input shaper does not guarantee a null residual vibration when it is convolved with any unshaped command. To obtain an analytically proven zero-vibration response, it is required to include the parameters that characterize the response of the system to a selected normalized unshaped command in the formulation. By introducing an appropriate processing time delay and by measuring the initial states using a feedback sensor, the proposed method has been applied in a real time scenario where an emergency stop of a crane is required, assuming that initially the payload is swaying.A mathematical model to study railway track dynamics for the prediction of vibration levels generated by rail vehiclesOtero Yugat, JesúsMartínez Miralles, Jordi RamonSantos López, M. Antonia de losCardona Foix, Salvadorhttp://hdl.handle.net/2117/875912023-09-10T11:12:55Z2016-06-01T12:51:17ZA mathematical model to study railway track dynamics for the prediction of vibration levels generated by rail vehicles
Otero Yugat, Jesús; Martínez Miralles, Jordi Ramon; Santos López, M. Antonia de los; Cardona Foix, Salvador
This article presents a mathematical model aimed at predicting wheel–rail contact vibration force arising from wheel profile irregularities. Prediction of vibrations caused by a passing train is a basic factor in environmental impact studies related to planning new railway lines. The prediction model is useful during the development of a project as it facilitates selection of the most suitable track for reducing vibration levels. This article presents the model, analyses the influence of the track base on the vibration-generating mechanisms, and compares the dynamic behaviour of the most widely used urban railway tracks.
2016-06-01T12:51:17ZOtero Yugat, JesúsMartínez Miralles, Jordi RamonSantos López, M. Antonia de losCardona Foix, SalvadorThis article presents a mathematical model aimed at predicting wheel–rail contact vibration force arising from wheel profile irregularities. Prediction of vibrations caused by a passing train is a basic factor in environmental impact studies related to planning new railway lines. The prediction model is useful during the development of a project as it facilitates selection of the most suitable track for reducing vibration levels. This article presents the model, analyses the influence of the track base on the vibration-generating mechanisms, and compares the dynamic behaviour of the most widely used urban railway tracks.Evaluation of the influence of a planned interference fit on the expected fatigue life of a conjugate cam mechanism- A case studyCatalà Calderon, PauSantos López, M. Antonia de losVeciana Fontanet, Joaquim MariaCardona Foix, Salvadorhttp://hdl.handle.net/2117/866772021-09-19T10:25:50Z2016-05-06T09:39:52ZEvaluation of the influence of a planned interference fit on the expected fatigue life of a conjugate cam mechanism- A case study
Català Calderon, Pau; Santos López, M. Antonia de los; Veciana Fontanet, Joaquim Maria; Cardona Foix, Salvador
Due to dynamic effects, clearances, manufacturing and assembly errors in form-closed cam mechanisms, the follower jump can also occur. For conjugate cam mechanisms a technique to avoid the follower jump without the use of a spring involves making the conjugate cam profiles bigger than the kinematical ones by adding an external offset. This strategy produces an interference fit between the conjugate cam profiles and the follower train. This paper presents an ordered procedure to study the influence that the planned interference fit has on the evaluation of the contact forces, the expected fatigue life of the
rollers, contact pressures and the lubrication conditions. The study is based on a conjugate cam mechanism with translational roller followers used in a real automatic process for manufacturing muselets. A three-degree-of-freedom dynamic model is proposed and the Hertzian theory for general profiles is used to model the nonlinear contact stiffness between the cams and the crowned rollers. The dynamic model predicts that it is difficult to obtain conjugate cam mechanisms with an infinite expected fatigue life of the rollers just by considering typical achievable manufacturing errors or clearances, and as happens in reality, a set-up process is highly recommended. The procedure is also tested with measured manufacturing errors on a coordinate measure machine—CMM—and with measured radial internal clearances for the rollers measured by an experimental apparatus.
Also, to evaluate lubrication conditions, surface finishing measurements have been taken of the cams and the rollers with a surface profiler.
2016-05-06T09:39:52ZCatalà Calderon, PauSantos López, M. Antonia de losVeciana Fontanet, Joaquim MariaCardona Foix, SalvadorDue to dynamic effects, clearances, manufacturing and assembly errors in form-closed cam mechanisms, the follower jump can also occur. For conjugate cam mechanisms a technique to avoid the follower jump without the use of a spring involves making the conjugate cam profiles bigger than the kinematical ones by adding an external offset. This strategy produces an interference fit between the conjugate cam profiles and the follower train. This paper presents an ordered procedure to study the influence that the planned interference fit has on the evaluation of the contact forces, the expected fatigue life of the
rollers, contact pressures and the lubrication conditions. The study is based on a conjugate cam mechanism with translational roller followers used in a real automatic process for manufacturing muselets. A three-degree-of-freedom dynamic model is proposed and the Hertzian theory for general profiles is used to model the nonlinear contact stiffness between the cams and the crowned rollers. The dynamic model predicts that it is difficult to obtain conjugate cam mechanisms with an infinite expected fatigue life of the rollers just by considering typical achievable manufacturing errors or clearances, and as happens in reality, a set-up process is highly recommended. The procedure is also tested with measured manufacturing errors on a coordinate measure machine—CMM—and with measured radial internal clearances for the rollers measured by an experimental apparatus.
Also, to evaluate lubrication conditions, surface finishing measurements have been taken of the cams and the rollers with a surface profiler.Modified adaptive input shaping for maneuvering cranes using a feedback MEM gyroscope with null driftVeciana Fontanet, Joaquim MariaCardona Foix, SalvadorCatalà Calderon, Pauhttp://hdl.handle.net/2117/829462021-09-19T08:09:05Z2016-02-15T14:08:16ZModified adaptive input shaping for maneuvering cranes using a feedback MEM gyroscope with null drift
Veciana Fontanet, Joaquim Maria; Cardona Foix, Salvador; Català Calderon, Pau
This paper presents an adaptive algorithm to reduce residual vibrations when the feedback sensor used has null drift along the time. The adaptive approaches are useful to deal with large variations of the system parameters at each maneuver, such as it occurs in cranes. For the feedback sensor, the use of inertial measurement units such as Micro-Electro-Mechanical Systems (MEMS) is increasingly extended because of their cost, size, robustness and power consumption. However, the effectiveness of the adaptive input shaping algorithms is compromised because of this drift, which is a commonly raised issue in this kind of devices. The study presented in this manuscript focuses on the development of an automatic compensation of this drift to obviate frequent calibrations. It is based on a non-asymptotic algebraic identification technique, which does not require initial conditions and has a short convergence time. This study uses the Zero-Vibration (ZV) input shaper technique, and the null drift is added to the algorithm as a parameter to be identified. The proposed method is particularized for single maneuvers of cranes with a gyroscope as feedback sensor, in a real time scenario. Experimental results show the efficacy of the method on a scaled crane test platform.
2016-02-15T14:08:16ZVeciana Fontanet, Joaquim MariaCardona Foix, SalvadorCatalà Calderon, PauThis paper presents an adaptive algorithm to reduce residual vibrations when the feedback sensor used has null drift along the time. The adaptive approaches are useful to deal with large variations of the system parameters at each maneuver, such as it occurs in cranes. For the feedback sensor, the use of inertial measurement units such as Micro-Electro-Mechanical Systems (MEMS) is increasingly extended because of their cost, size, robustness and power consumption. However, the effectiveness of the adaptive input shaping algorithms is compromised because of this drift, which is a commonly raised issue in this kind of devices. The study presented in this manuscript focuses on the development of an automatic compensation of this drift to obviate frequent calibrations. It is based on a non-asymptotic algebraic identification technique, which does not require initial conditions and has a short convergence time. This study uses the Zero-Vibration (ZV) input shaper technique, and the null drift is added to the algorithm as a parameter to be identified. The proposed method is particularized for single maneuvers of cranes with a gyroscope as feedback sensor, in a real time scenario. Experimental results show the efficacy of the method on a scaled crane test platform.The use of hybrid CO2+MQL in machining operationsPereira, OctavioCatalà Calderon, PauRodríguez, AdrianOstra, TxominVivancos Calvet, JoanRivero, AsunciónLópez de Lacalle, Luis Norbertohttp://hdl.handle.net/2117/822642021-09-19T07:31:18Z2016-01-29T11:30:30ZThe use of hybrid CO2+MQL in machining operations
Pereira, Octavio; Català Calderon, Pau; Rodríguez, Adrian; Ostra, Txomin; Vivancos Calvet, Joan; Rivero, Asunción; López de Lacalle, Luis Norberto
Nowadays, the environmental concern in machining industry is a fact. Because of that, in this article a new cooling-lubrication
system which combines CO2 cryogenic and MQL technologies is presented. The aim of this new cooling-lubrication system is to
offer an ecological and economic efficient alternative. Two nozzle adapters are proposed with different CO2 outlets. The
developed nozzles are Plug & Play and directly applicable to commercial MQL systems. The behaviors of nozzle adapters were
simulated by CFD (Computational Fluid Dynamics) and the optimal nozzle adapter was tested by milling Inconel 718 ®. In these
milling tests, the tool life was measured and using different main cooling-lubrication techniques: dry, wet, CO2 stand alone, MQL
stand alone and CO2+MQL (proposed alternative).
2016-01-29T11:30:30ZPereira, OctavioCatalà Calderon, PauRodríguez, AdrianOstra, TxominVivancos Calvet, JoanRivero, AsunciónLópez de Lacalle, Luis NorbertoNowadays, the environmental concern in machining industry is a fact. Because of that, in this article a new cooling-lubrication
system which combines CO2 cryogenic and MQL technologies is presented. The aim of this new cooling-lubrication system is to
offer an ecological and economic efficient alternative. Two nozzle adapters are proposed with different CO2 outlets. The
developed nozzles are Plug & Play and directly applicable to commercial MQL systems. The behaviors of nozzle adapters were
simulated by CFD (Computational Fluid Dynamics) and the optimal nozzle adapter was tested by milling Inconel 718 ®. In these
milling tests, the tool life was measured and using different main cooling-lubrication techniques: dry, wet, CO2 stand alone, MQL
stand alone and CO2+MQL (proposed alternative).Use of single board computers as smart sensors in the manufacturing industryGomez, AgustinCuiñas Vázquez, DanielCatalà Calderon, PauXin, LinLi, WeidongConway, StewartLack, Donaldhttp://hdl.handle.net/2117/822572021-09-19T07:23:37Z2016-01-29T09:49:51ZUse of single board computers as smart sensors in the manufacturing industry
Gomez, Agustin; Cuiñas Vázquez, Daniel; Català Calderon, Pau; Xin, Lin; Li, Weidong; Conway, Stewart; Lack, Donald
The continuously growing presence of cyber-physical systems in the industry, especially in the field of processes automation and control, represents the paradigm of the so called fourth industrial revolution, in which the systems are smarter, faster and more optimized by means of artificial intelligence, control systems and sensors networks. The presence of ICT and automation systems guarantees energy and other resources efficiency along the whole value chain of industrial processes. Especially important is the case of the smart sensors, in which a conventional sensor is equipped with interfacing methodologies for signal processing and decision making. In this article the capabilities of using a single board computer as a smart sensor are explored.
2016-01-29T09:49:51ZGomez, AgustinCuiñas Vázquez, DanielCatalà Calderon, PauXin, LinLi, WeidongConway, StewartLack, DonaldThe continuously growing presence of cyber-physical systems in the industry, especially in the field of processes automation and control, represents the paradigm of the so called fourth industrial revolution, in which the systems are smarter, faster and more optimized by means of artificial intelligence, control systems and sensors networks. The presence of ICT and automation systems guarantees energy and other resources efficiency along the whole value chain of industrial processes. Especially important is the case of the smart sensors, in which a conventional sensor is equipped with interfacing methodologies for signal processing and decision making. In this article the capabilities of using a single board computer as a smart sensor are explored.Avoiding early failures in conjugate cam mechanism by means of different design strategiesCatalà Calderon, PauSantos López, M. Antonia de losVeciana Fontanet, Joaquim MariaCardona Foix, Salvadorhttp://hdl.handle.net/2117/822172021-09-19T07:11:27Z2016-01-28T11:48:52ZAvoiding early failures in conjugate cam mechanism by means of different design strategies
Català Calderon, Pau; Santos López, M. Antonia de los; Veciana Fontanet, Joaquim Maria; Cardona Foix, Salvador
To solve the indetermination of forces existing in a form-closed cam mechanism formed by conjugate cams, where the contact between the cams and the follower rollers is constantly ensured by only the geometry of the elements, dynamic models that consider the elasticity of the elements must be proposed. Because the stiffness of the main elements is associated with the elasticity of the solids, tight variations in manufacturing and assembly errors modify the effective interference fit, which significantly affects the expected fatigue life of the mechanism, leading to a premature failure of the elements due to surface fatigue. Based on a real industrial application of a conjugate cam mechanism and using lumped-parameter models, the objectives of this paper are: first, to show that it is difficult to achieve a pure form-closed conjugate cam mechanism, with the expected fatigue life of the mechanism, by using only standard tolerance specifications; second, to compare the expected fatigue life and motor torque with other cam mechanism design strategies such as force-closed and the combination of force-closed and form-closed strategies, known as force-closed conjugate cam strategy. This paper based on simulation results demonstrates that this latest strategy can, thanks to a better control of the preload, easily achieve results very similar to the theoretical ones of a form-closed conjugate cam mechanism. A prototype of the mechanism of the force-closed conjugate cam strategy is also built.
2016-01-28T11:48:52ZCatalà Calderon, PauSantos López, M. Antonia de losVeciana Fontanet, Joaquim MariaCardona Foix, SalvadorTo solve the indetermination of forces existing in a form-closed cam mechanism formed by conjugate cams, where the contact between the cams and the follower rollers is constantly ensured by only the geometry of the elements, dynamic models that consider the elasticity of the elements must be proposed. Because the stiffness of the main elements is associated with the elasticity of the solids, tight variations in manufacturing and assembly errors modify the effective interference fit, which significantly affects the expected fatigue life of the mechanism, leading to a premature failure of the elements due to surface fatigue. Based on a real industrial application of a conjugate cam mechanism and using lumped-parameter models, the objectives of this paper are: first, to show that it is difficult to achieve a pure form-closed conjugate cam mechanism, with the expected fatigue life of the mechanism, by using only standard tolerance specifications; second, to compare the expected fatigue life and motor torque with other cam mechanism design strategies such as force-closed and the combination of force-closed and form-closed strategies, known as force-closed conjugate cam strategy. This paper based on simulation results demonstrates that this latest strategy can, thanks to a better control of the preload, easily achieve results very similar to the theoretical ones of a form-closed conjugate cam mechanism. A prototype of the mechanism of the force-closed conjugate cam strategy is also built.Integration of product conceptual design synthesis into a Computer-Aided Design systemÁlvarez Cabrales, AlexisZayas Figueras, Enrique ErnestoPérez Rodríguez, RobertoSimeón, RolandoRiba Romeva, CarlesCardona Foix, Salvadorhttp://hdl.handle.net/2117/269432021-03-11T15:09:10Z2015-03-23T13:33:09ZIntegration of product conceptual design synthesis into a Computer-Aided Design system
Álvarez Cabrales, Alexis; Zayas Figueras, Enrique Ernesto; Pérez Rodríguez, Roberto; Simeón, Rolando; Riba Romeva, Carles; Cardona Foix, Salvador
Commercial Computer-Aided Design systems have mainly focused to support the process of capturing and representing geometric shapes and incorporating technological information. In contrast, few utilities in these systems are present to facilitate decision making in the early stages of the design process, such as the capture, modeling and conceptual design synthesis of solutions. Typical tasks of the conceptual design process in mechanical design are lead in applications stand-alone or are based on the heuristic knowledge of the designer. Such approaches are non-interoperable with de commercial computer-aided design systems, leading to discontinuous design information of design process. This study addresses this subject and proposes a method to improve the integration of product conceptual design synthesis into a Computer Aided Design system. To validate the feasibility of the approach implemented, a prototype application based on a Computer Aided Design system was developed and a study case was accomplished
2015-03-23T13:33:09ZÁlvarez Cabrales, AlexisZayas Figueras, Enrique ErnestoPérez Rodríguez, RobertoSimeón, RolandoRiba Romeva, CarlesCardona Foix, SalvadorCommercial Computer-Aided Design systems have mainly focused to support the process of capturing and representing geometric shapes and incorporating technological information. In contrast, few utilities in these systems are present to facilitate decision making in the early stages of the design process, such as the capture, modeling and conceptual design synthesis of solutions. Typical tasks of the conceptual design process in mechanical design are lead in applications stand-alone or are based on the heuristic knowledge of the designer. Such approaches are non-interoperable with de commercial computer-aided design systems, leading to discontinuous design information of design process. This study addresses this subject and proposes a method to improve the integration of product conceptual design synthesis into a Computer Aided Design system. To validate the feasibility of the approach implemented, a prototype application based on a Computer Aided Design system was developed and a study case was accomplishedRadius of curvature and sliding velocity in constant-breadth cam mechanismsCardona Foix, SalvadorZayas Figueras, Enrique ErnestoJordi Nebot, Lluïsahttp://hdl.handle.net/2117/268522021-03-11T13:14:36Z2015-03-19T13:33:19ZRadius of curvature and sliding velocity in constant-breadth cam mechanisms
Cardona Foix, Salvador; Zayas Figueras, Enrique Ernesto; Jordi Nebot, Lluïsa
In constant-breadth cam mechanisms closure of the higher kinematic pairs formed by the bilateral cam-follower contact is guaranteed by the geometry of both cam and follower. A study of the cam profile by means of its radius of curvature and the sliding velocities in the upper pair enables us to predict the correct functioning of the mechanism. This work presents the equations for calculating cam breadth when the translating follower is eccentric with an inclination, the radius of curvature of its profile and the sliding velocities of constant-breadth cam mechanisms with translating and oscillating followers. This study also analyses the influence of the angle of inclination and the offset of the flat-faced translating followers on the size of the cam and the kinematics of the mechanism. Numerical examples are given of constant-breadth cams obtained for distinct values of the mentioned parameters. Additionally, this paper describes the redesign of a cam of a conventional sewing machine and the new cam prototype, with a continuity of an order higher than the original profile, is included. (C) 2014 Elsevier Ltd. All rights reserved.
2015-03-19T13:33:19ZCardona Foix, SalvadorZayas Figueras, Enrique ErnestoJordi Nebot, LluïsaIn constant-breadth cam mechanisms closure of the higher kinematic pairs formed by the bilateral cam-follower contact is guaranteed by the geometry of both cam and follower. A study of the cam profile by means of its radius of curvature and the sliding velocities in the upper pair enables us to predict the correct functioning of the mechanism. This work presents the equations for calculating cam breadth when the translating follower is eccentric with an inclination, the radius of curvature of its profile and the sliding velocities of constant-breadth cam mechanisms with translating and oscillating followers. This study also analyses the influence of the angle of inclination and the offset of the flat-faced translating followers on the size of the cam and the kinematics of the mechanism. Numerical examples are given of constant-breadth cams obtained for distinct values of the mentioned parameters. Additionally, this paper describes the redesign of a cam of a conventional sewing machine and the new cam prototype, with a continuity of an order higher than the original profile, is included. (C) 2014 Elsevier Ltd. All rights reserved.Enhancement in evaluating small group work in courses with large number of students. Machine theory at industrial engineering degreesJordi Nebot, LluïsaPàmies Vilà, RosaCatalà Calderon, PauPuig Ortiz, Joanhttp://hdl.handle.net/2117/187322021-09-19T05:58:20Z2013-04-09T11:49:48ZEnhancement in evaluating small group work in courses with large number of students. Machine theory at industrial engineering degrees
Jordi Nebot, Lluïsa; Pàmies Vilà, Rosa; Català Calderon, Pau; Puig Ortiz, Joan
2013-04-09T11:49:48ZJordi Nebot, LluïsaPàmies Vilà, RosaCatalà Calderon, PauPuig Ortiz, Joan