A simple quadrilateral shell element is proposed in this work to study large deformations and large rotations of membrane/plate/shell structures. There are three merit characters in this element: locking-free; immune to mesh distortions; and robust to surface tessellations. Numerical issues in plates/shell elements such as shear-locking and thickness-locking problems are resolved, and quadrilateral area coordinates are adopted to solve the mesh distortion issues. This element can be adopted to curved shell structures, and warped deformations can be well described. Moreover, even if a shell structure cannot be easily tessellated by high quality quadrilateral polygons, it can still be discretized by a mesh consisting of high-quality triangular and quadrilateral elements, then this element can work together with a corresponding triangular element to provide accurate results on this combined mesh, and the degree of freedom for the discretized system is no more than several times of the number of nodes. Numerical tests validate the effectiveness, efficiency and universality of this element in engineering scenarios.
{"title":"A Universal Quadrilateral Shell Element for the Absolute Nodal Coordinate Formulation","authors":"Binghua Zhang, W. Fan, H. Ren","doi":"10.1115/1.4062630","DOIUrl":"https://doi.org/10.1115/1.4062630","url":null,"abstract":"\u0000 A simple quadrilateral shell element is proposed in this work to study large deformations and large rotations of membrane/plate/shell structures. There are three merit characters in this element: locking-free; immune to mesh distortions; and robust to surface tessellations. Numerical issues in plates/shell elements such as shear-locking and thickness-locking problems are resolved, and quadrilateral area coordinates are adopted to solve the mesh distortion issues. This element can be adopted to curved shell structures, and warped deformations can be well described. Moreover, even if a shell structure cannot be easily tessellated by high quality quadrilateral polygons, it can still be discretized by a mesh consisting of high-quality triangular and quadrilateral elements, then this element can work together with a corresponding triangular element to provide accurate results on this combined mesh, and the degree of freedom for the discretized system is no more than several times of the number of nodes. Numerical tests validate the effectiveness, efficiency and universality of this element in engineering scenarios.","PeriodicalId":54858,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"107 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89641580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alberto Baldassarri, Michele Bertelli, M. Carricato
This paper addresses the design of a reconfigurable mobile manipulator consisting of a mobile base and a collaborative serial robot. The robotic system is meant to work in an industrial environment and perform different logistic tasks. Unlike commercial solutions, the mobile base and the anthropomorphic arm are free to decouple and work separately as two different entities, thus optimizing working times and maximize the hardware utilization ratio. The proposed mobile manipulator is equipped with: an automatic braking system to ensure safety and stability during manipulation, a lifting system that allows the robotic arm to work at different heights, and a spatial referencing process to compensate positioning error of the mobile base. An illustrative working cycle is implemented in an industrially-relevant environment to test all features and show potentialities, in terms of flexibility and reconfigurability, of the presented solution.
{"title":"Design of a Reconfigurable Mobile Collaborative Manipulator for Industrial Applications","authors":"Alberto Baldassarri, Michele Bertelli, M. Carricato","doi":"10.1115/1.4062595","DOIUrl":"https://doi.org/10.1115/1.4062595","url":null,"abstract":"\u0000 This paper addresses the design of a reconfigurable mobile manipulator consisting of a mobile base and a collaborative serial robot. The robotic system is meant to work in an industrial environment and perform different logistic tasks. Unlike commercial solutions, the mobile base and the anthropomorphic arm are free to decouple and work separately as two different entities, thus optimizing working times and maximize the hardware utilization ratio. The proposed mobile manipulator is equipped with: an automatic braking system to ensure safety and stability during manipulation, a lifting system that allows the robotic arm to work at different heights, and a spatial referencing process to compensate positioning error of the mobile base. An illustrative working cycle is implemented in an industrially-relevant environment to test all features and show potentialities, in terms of flexibility and reconfigurability, of the presented solution.","PeriodicalId":54858,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"15 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73952062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the synchronization problem of a class of fractional order chaotic systems with output variables. Based on the system output, the observer scheme is given to recover the state variables. By using the recovered state variables, some novel sufficient conditions for obtaining chaos synchronization are presented via the backstepping control approach. Numerical simulation is used to verify the practicability and effectiveness of the proposed scheme.
{"title":"The Synchronization of a Class Fractional-order Chaotic System by Using the Recovered State Variables and Backstepping Control","authors":"Haipeng Su, Luo Runzi","doi":"10.1115/1.4062568","DOIUrl":"https://doi.org/10.1115/1.4062568","url":null,"abstract":"\u0000 This paper investigates the synchronization problem of a class of fractional order chaotic systems with output variables. Based on the system output, the observer scheme is given to recover the state variables. By using the recovered state variables, some novel sufficient conditions for obtaining chaos synchronization are presented via the backstepping control approach. Numerical simulation is used to verify the practicability and effectiveness of the proposed scheme.","PeriodicalId":54858,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"120 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88595649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydraulic dampers are widely implemented in railway vehicle suspension stages, especially in high-speed passenger trains. They are designed to be mounted in different positions to improve comfort, stability, and safety performances. Numerical simulations are often used to assist the design and optimization of these components. Unfortunately, hydraulic dampers are highly nonlinear due to the complex fluid dynamic phenomena taking place inside the chambers and through the by-pass orifices. This requires accurate damper models to be developed to estimate the influence of the nonlinearities of such components during the dynamic performances of the whole vehicle. This work aims at presenting a new parametric damper model based on a nonlinear lumped element approach. Moreover, a new model tuning procedure will be introduced. Differently from the typical sinusoidal characterization cycles, this routine is based on experimental tests of real working conditions. The set of optimal model parameters will be found through a meta-heuristic iterative approach able to minimize the differences between numerical and experimental damper forces. The performances of the optimal model will be compared with the ones of the most common Maxwell model generally implemented in railway multibody software programs.
{"title":"A Meta-heuristic Optimization Procedure for the Identification of the Nonlinear Model Parameters of Hydraulic Dampers Based On Experimental Dataset of Real Working Conditions","authors":"G. Isacchi, F. Ripamonti, Matteo Corsi","doi":"10.1115/1.4062541","DOIUrl":"https://doi.org/10.1115/1.4062541","url":null,"abstract":"\u0000 Hydraulic dampers are widely implemented in railway vehicle suspension stages, especially in high-speed passenger trains. They are designed to be mounted in different positions to improve comfort, stability, and safety performances. Numerical simulations are often used to assist the design and optimization of these components. Unfortunately, hydraulic dampers are highly nonlinear due to the complex fluid dynamic phenomena taking place inside the chambers and through the by-pass orifices. This requires accurate damper models to be developed to estimate the influence of the nonlinearities of such components during the dynamic performances of the whole vehicle. This work aims at presenting a new parametric damper model based on a nonlinear lumped element approach. Moreover, a new model tuning procedure will be introduced. Differently from the typical sinusoidal characterization cycles, this routine is based on experimental tests of real working conditions. The set of optimal model parameters will be found through a meta-heuristic iterative approach able to minimize the differences between numerical and experimental damper forces. The performances of the optimal model will be compared with the ones of the most common Maxwell model generally implemented in railway multibody software programs.","PeriodicalId":54858,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"60 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87392791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andreas Mueller, Jozsef Kovecses, Charles Kim, Chandramouli Padmanabhan, Gabor Orosz
Robots are complex controlled dynamical systems interacting with their environment. Agile robotic systems have been penetrating almost all industrial sectors as the backbone for industrial automation, ranging from heavy duty manipulators to collaborative robots (cobots) and mobile platforms for logistics tasks. Currently, autonomous vehicles (e.g., cars, mobile delivery systems, drones, inspection, and maintenance) are entering the public sector, but also the use of surgical robots is becoming an integral part of medical treatments. In a foreseeable future, assistive robots for domestic use will become indispensable for caretaking and as exoskeletal devices providing physical support thus physically interacting with humans. Future robots need to be responsive; they must (inter)act safely, minimize the use of resources (energy, material, process-, development-, and commissioning-time), and adapt to variations in demands and environmental conditions.Advanced robotic systems are equipped with multimodal sensory systems, and are operated with model-based and model-free control schemes. Yet, the mechanical embodiment is the starting point of any robot design. Key to a reliable design and control of such robots are holistic design approaches embracing kinematic synthesis, dynamic analysis, control, sensory perception, and adaptability. Novel mechanical design principles, combining high-fidelity kinematic and dynamic models with data-driven methods, are applied along with model-free machine learning (ML) and artificial intelligence (AI) methods. The foundation is a synergetic combination of research in mechanism theory and dynamical systems and control.This joint special issue of the Journal of Mechanisms and Robotics (JMR) and the Journal of Computational and Nonlinear Dynamics (JCND) aims to bridge between these research fields and to bring together the latest research on robot kinematics and dynamics as well as intelligent control and data-driven methods for perception, planning, model identification, and control.This joint special issue is a collection of 13 papers published in JMR and 10 papers published in JCND, respectively. The papers published in JMR address several of the main research topics in robot design, namely, the design and control of agile and compliant robots intended for robust and safe interaction with its environment. The paper “Design, Calibration, and Control of Compliant Force-Sensing Gripping Pads for Humanoid Robots” introduces low-cost, light-weight, and compliant force-sensing gripping pads that enables smaller-sized humanoid robots to manipulate box-like objects. In “Dyno-Kinematic Leg Design for High Energy Robotic Locomotion,” technique for leg design for high energy robotic locomotion is presented that encodes desired dynamic features into the mechanical design. In the paper “Emerging Gaits for a Quadrupedal Template Model with Segmented Legs,” the gait stability of quadrupedal robots with articulated elastic legs is st
{"title":"Joint Special Issue: Design and Control of Responsive Robots","authors":"Andreas Mueller, Jozsef Kovecses, Charles Kim, Chandramouli Padmanabhan, Gabor Orosz","doi":"10.1115/1.4062416","DOIUrl":"https://doi.org/10.1115/1.4062416","url":null,"abstract":"Robots are complex controlled dynamical systems interacting with their environment. Agile robotic systems have been penetrating almost all industrial sectors as the backbone for industrial automation, ranging from heavy duty manipulators to collaborative robots (cobots) and mobile platforms for logistics tasks. Currently, autonomous vehicles (e.g., cars, mobile delivery systems, drones, inspection, and maintenance) are entering the public sector, but also the use of surgical robots is becoming an integral part of medical treatments. In a foreseeable future, assistive robots for domestic use will become indispensable for caretaking and as exoskeletal devices providing physical support thus physically interacting with humans. Future robots need to be responsive; they must (inter)act safely, minimize the use of resources (energy, material, process-, development-, and commissioning-time), and adapt to variations in demands and environmental conditions.Advanced robotic systems are equipped with multimodal sensory systems, and are operated with model-based and model-free control schemes. Yet, the mechanical embodiment is the starting point of any robot design. Key to a reliable design and control of such robots are holistic design approaches embracing kinematic synthesis, dynamic analysis, control, sensory perception, and adaptability. Novel mechanical design principles, combining high-fidelity kinematic and dynamic models with data-driven methods, are applied along with model-free machine learning (ML) and artificial intelligence (AI) methods. The foundation is a synergetic combination of research in mechanism theory and dynamical systems and control.This joint special issue of the Journal of Mechanisms and Robotics (JMR) and the Journal of Computational and Nonlinear Dynamics (JCND) aims to bridge between these research fields and to bring together the latest research on robot kinematics and dynamics as well as intelligent control and data-driven methods for perception, planning, model identification, and control.This joint special issue is a collection of 13 papers published in JMR and 10 papers published in JCND, respectively. The papers published in JMR address several of the main research topics in robot design, namely, the design and control of agile and compliant robots intended for robust and safe interaction with its environment. The paper “Design, Calibration, and Control of Compliant Force-Sensing Gripping Pads for Humanoid Robots” introduces low-cost, light-weight, and compliant force-sensing gripping pads that enables smaller-sized humanoid robots to manipulate box-like objects. In “Dyno-Kinematic Leg Design for High Energy Robotic Locomotion,” technique for leg design for high energy robotic locomotion is presented that encodes desired dynamic features into the mechanical design. In the paper “Emerging Gaits for a Quadrupedal Template Model with Segmented Legs,” the gait stability of quadrupedal robots with articulated elastic legs is st","PeriodicalId":54858,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136056482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lorenzo Bartali, Marco Gabiccini, Massimo Guiggiani
Abstract This paper presents an automatic procedure to enhance the accuracy of the numerical solution of an optimal control problem (OCP) discretized via direct collocation at Gauss–Legendre points. First, a numerical solution is obtained by solving a nonlinear program (NLP). Then, the method evaluates its accuracy and adaptively changes both the degree of the approximating polynomial within each mesh interval and the number of mesh intervals until a prescribed accuracy is met. The number of mesh intervals is increased for all state vector components alike, in a classical fashion. Instead, improving on state-of-the-art procedures, the degrees of the polynomials approximating the different components of the state vector are allowed to assume, in each finite element, distinct values. This explains the pnh definition, where n is the state dimension. With respect to the approaches found in the literature, where the degree is always raised to the highest order for all the state components, our methods allow a sensible reduction of the overall number of variables of the resulting NLP, with a corresponding reduction of the computational burden. Numerical tests on three OCP problems highlight that, under the same maximum allowable error, by independently selecting the degree of the polynomial for each state, our method effectively picks lower degrees for some of the states, thus reducing the overall number of variables in the NLP. Accordingly, various advantages are brought about, the most remarkable being: (i) an increased computational efficiency for the final enhanced mesh with solution accuracy still within the prescribed tolerance, (ii) a reduced risk of being trapped by local minima due to the reduced NLP size, and (iii) a gain of the robustness of the convergence process due to the better-behaved solution landscapes.
{"title":"A <i>pnh</i>-Adaptive Refinement Procedure for Numerical Optimal Control Problems","authors":"Lorenzo Bartali, Marco Gabiccini, Massimo Guiggiani","doi":"10.1115/1.4062227","DOIUrl":"https://doi.org/10.1115/1.4062227","url":null,"abstract":"Abstract This paper presents an automatic procedure to enhance the accuracy of the numerical solution of an optimal control problem (OCP) discretized via direct collocation at Gauss–Legendre points. First, a numerical solution is obtained by solving a nonlinear program (NLP). Then, the method evaluates its accuracy and adaptively changes both the degree of the approximating polynomial within each mesh interval and the number of mesh intervals until a prescribed accuracy is met. The number of mesh intervals is increased for all state vector components alike, in a classical fashion. Instead, improving on state-of-the-art procedures, the degrees of the polynomials approximating the different components of the state vector are allowed to assume, in each finite element, distinct values. This explains the pnh definition, where n is the state dimension. With respect to the approaches found in the literature, where the degree is always raised to the highest order for all the state components, our methods allow a sensible reduction of the overall number of variables of the resulting NLP, with a corresponding reduction of the computational burden. Numerical tests on three OCP problems highlight that, under the same maximum allowable error, by independently selecting the degree of the polynomial for each state, our method effectively picks lower degrees for some of the states, thus reducing the overall number of variables in the NLP. Accordingly, various advantages are brought about, the most remarkable being: (i) an increased computational efficiency for the final enhanced mesh with solution accuracy still within the prescribed tolerance, (ii) a reduced risk of being trapped by local minima due to the reduced NLP size, and (iii) a gain of the robustness of the convergence process due to the better-behaved solution landscapes.","PeriodicalId":54858,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136265865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Usage of contact mechanics methodologies is a pervasive modeling requirement in dynamic simulations. While for some trivial problems, solutions taken from analytical geometry are available, use of a finite element framework is common to achieve formulation generality. This work explores two dynamic contact formulations: one based on the traditional node-to-segment (NTS) approach, and a variationally consistent segment-to-segment (STS) mortar formulation. The NTS formulation employed here enforces the constraints kinematically (i.e., the interpenetration is enforced to the solver tolerance), whereas the mortar approach uses Lagrange multipliers to enforce the contact constraints. Both approaches are implemented in the open-source finite element framework Multiphysics Object-Oriented Simulation Environment (MOOSE). The results highlight two relevant contact-interface-related dynamic phenomena in finite element simulations. First, stabilization of contact constraints is discussed, taking into account the evolution of the total energy in a benchmark problem. Second, the influence of finite element discretization on both of the aforementioned contact formulations is analyzed by exercising a large-deformation example with continuous relative sliding. Variationally consistent contact approaches such as the mortar formulation lead to improved energy preservation and avoid spurious excitation of the system's frequencies. This is especially relevant in settings where inertia and vibrations are of importance.
{"title":"On Practical Aspects of Variational Consistency in Contact Dynamics","authors":"Antonio Recuero, Alexander Lindsay","doi":"10.1115/1.4056589","DOIUrl":"https://doi.org/10.1115/1.4056589","url":null,"abstract":"Abstract Usage of contact mechanics methodologies is a pervasive modeling requirement in dynamic simulations. While for some trivial problems, solutions taken from analytical geometry are available, use of a finite element framework is common to achieve formulation generality. This work explores two dynamic contact formulations: one based on the traditional node-to-segment (NTS) approach, and a variationally consistent segment-to-segment (STS) mortar formulation. The NTS formulation employed here enforces the constraints kinematically (i.e., the interpenetration is enforced to the solver tolerance), whereas the mortar approach uses Lagrange multipliers to enforce the contact constraints. Both approaches are implemented in the open-source finite element framework Multiphysics Object-Oriented Simulation Environment (MOOSE). The results highlight two relevant contact-interface-related dynamic phenomena in finite element simulations. First, stabilization of contact constraints is discussed, taking into account the evolution of the total energy in a benchmark problem. Second, the influence of finite element discretization on both of the aforementioned contact formulations is analyzed by exercising a large-deformation example with continuous relative sliding. Variationally consistent contact approaches such as the mortar formulation lead to improved energy preservation and avoid spurious excitation of the system's frequencies. This is especially relevant in settings where inertia and vibrations are of importance.","PeriodicalId":54858,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136265857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Sophisticated modeling and simulation, based on rigid and flexible multibody dynamics, are nowadays a standard procedure in the design and analysis of vehicle systems and are widely adopted for on-road driving. Off-road driving for both terrestrial wheeled and tracked vehicles, as well as wheeled and legged robots and rovers for extra-terrestrial exploration pose additional modeling and simulation challenges, a primary one being that of the vehicle–terrain interaction, modeling of deformable terrain, and terramechanics in general. Techniques for modeling deformable terrain span an entire range varying in complexity, representation accuracy, and ensuing computational effort. While formulations such as fully resolved granular dynamics, continuum representation of granular material, or finite element can provide a high level of accuracy, they do so at a significant cost, even when the implementation leverages parallel computing and/or hardware accelerators. Real-time or faster than real-time terramechanics is a highly desired capability (in applications such as training of autonomous vehicles and robotic systems) or critical capability (in applications such as human-in-the-loop or hardware-in-the-loop). We present a real-time capable deformable soil implementation, extended from the soil contact model (SCM) developed at the German Aerospace Center which in turn can be viewed as a generalization of the Bekker-Wong and Janosi-Hanamoto semi-empirical models for soil interaction with arbitrary three-dimensional shapes and arbitrary contact patches. This SCM implementation is available, alongside more computationally intensive deformable soil representations, in the open-source multiphysics package Chrono. We describe the overall implementation and the features of the Chrono SCM model, the efficient underlying data structures, the current multicore parallelization aspects, and its scalability properties for concurrent simulation of multiple vehicles on deformable terrain.
{"title":"Real-Time Simulation of Ground Vehicles on Deformable Terrain","authors":"Radu Serban, Jay Taves, Jason Zhou","doi":"10.1115/1.4056851","DOIUrl":"https://doi.org/10.1115/1.4056851","url":null,"abstract":"Abstract Sophisticated modeling and simulation, based on rigid and flexible multibody dynamics, are nowadays a standard procedure in the design and analysis of vehicle systems and are widely adopted for on-road driving. Off-road driving for both terrestrial wheeled and tracked vehicles, as well as wheeled and legged robots and rovers for extra-terrestrial exploration pose additional modeling and simulation challenges, a primary one being that of the vehicle–terrain interaction, modeling of deformable terrain, and terramechanics in general. Techniques for modeling deformable terrain span an entire range varying in complexity, representation accuracy, and ensuing computational effort. While formulations such as fully resolved granular dynamics, continuum representation of granular material, or finite element can provide a high level of accuracy, they do so at a significant cost, even when the implementation leverages parallel computing and/or hardware accelerators. Real-time or faster than real-time terramechanics is a highly desired capability (in applications such as training of autonomous vehicles and robotic systems) or critical capability (in applications such as human-in-the-loop or hardware-in-the-loop). We present a real-time capable deformable soil implementation, extended from the soil contact model (SCM) developed at the German Aerospace Center which in turn can be viewed as a generalization of the Bekker-Wong and Janosi-Hanamoto semi-empirical models for soil interaction with arbitrary three-dimensional shapes and arbitrary contact patches. This SCM implementation is available, alongside more computationally intensive deformable soil representations, in the open-source multiphysics package Chrono. We describe the overall implementation and the features of the Chrono SCM model, the efficient underlying data structures, the current multicore parallelization aspects, and its scalability properties for concurrent simulation of multiple vehicles on deformable terrain.","PeriodicalId":54858,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136265859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This study examines the nonlinear dynamics in tapping-mode atomic force microscopy (AFM) with tip-surface interactions that include van der Waals and Derjaguin-Müller-Toporov contact forces. We investigate the periodic solutions of the hybrid system by performing numerical pseudo-arclength continuation. Through the use of bifurcation locus maps in the set of parameters of the discontinuous model, the overall dynamical response scenario is assessed. We demonstrate the influence of various dissipation mechanisms that are related with the AFM touching or lacking contact with the sample. Local and global analyses are used to investigate the stability of the stable solution in the repulsive regime. The impacting nonsmooth dynamics framed within a higher-mode Galerkin discretization is able to capture windows of irregular and complex motion.
摘要:本研究考察了带有van der Waals和derjaguin - m - ller- toporov接触力的尖端-表面相互作用的轻敲模式原子力显微镜(AFM)的非线性动力学。通过数值拟弧长延拓研究了混合系统的周期解。通过在不连续模型的参数集上使用分岔轨迹映射，对整体动力响应情景进行了评估。我们演示了与AFM接触或缺乏与样品接触有关的各种耗散机制的影响。用局部分析和全局分析方法研究了排斥力状态下稳定解的稳定性。在高模伽辽金离散化框架内的碰撞非光滑动力学能够捕获不规则和复杂运动的窗口。
{"title":"Non-Smooth Dynamics of Tapping Mode Atomic Force Microscopy","authors":"Pierpaolo Belardinelli, Abhilash Chandrashekar, Farbod Alijani, Stefano Lenci","doi":"10.1115/1.4062228","DOIUrl":"https://doi.org/10.1115/1.4062228","url":null,"abstract":"Abstract This study examines the nonlinear dynamics in tapping-mode atomic force microscopy (AFM) with tip-surface interactions that include van der Waals and Derjaguin-Müller-Toporov contact forces. We investigate the periodic solutions of the hybrid system by performing numerical pseudo-arclength continuation. Through the use of bifurcation locus maps in the set of parameters of the discontinuous model, the overall dynamical response scenario is assessed. We demonstrate the influence of various dissipation mechanisms that are related with the AFM touching or lacking contact with the sample. Local and global analyses are used to investigate the stability of the stable solution in the repulsive regime. The impacting nonsmooth dynamics framed within a higher-mode Galerkin discretization is able to capture windows of irregular and complex motion.","PeriodicalId":54858,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136265864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This study is interested in the stability of robots in machining. The goal is to improve the dynamic performance of robots using an additional acceleration signal fed back through the conventional built-in proportional-derivative controller provided by the manufacturer. The structure of the robot is modelled with a simple one degree-of-freedom lumped model and the control signals are fed back via a linear spring and damping. The time delays of the feedback controllers are considered as zero-order holds, which results in sawtooth-like time-periodic time delays. The resulting equation of motion is an advanced delay differential equation. The semidiscretization method is shown for such systems having multiple sampled digital delays and continuous delays. First, we establish the stable regions in the plane of the sampling delay and the gain of the acceleration signal without machining. Then, we show the possibility to improve stability in turning and milling using the additional acceleration feedback controller compared to the cases without any controller or using only the built-in proportional-derivative controller.
{"title":"Stability Analysis of a One Degree of Freedom Robot Model with Sampled Digital Acceleration Feedback Controller in Turning and Milling","authors":"Andras Bartfai, Asier Barrios, Zoltan Dombovari","doi":"10.1115/1.4062229","DOIUrl":"https://doi.org/10.1115/1.4062229","url":null,"abstract":"Abstract This study is interested in the stability of robots in machining. The goal is to improve the dynamic performance of robots using an additional acceleration signal fed back through the conventional built-in proportional-derivative controller provided by the manufacturer. The structure of the robot is modelled with a simple one degree-of-freedom lumped model and the control signals are fed back via a linear spring and damping. The time delays of the feedback controllers are considered as zero-order holds, which results in sawtooth-like time-periodic time delays. The resulting equation of motion is an advanced delay differential equation. The semidiscretization method is shown for such systems having multiple sampled digital delays and continuous delays. First, we establish the stable regions in the plane of the sampling delay and the gain of the acceleration signal without machining. Then, we show the possibility to improve stability in turning and milling using the additional acceleration feedback controller compared to the cases without any controller or using only the built-in proportional-derivative controller.","PeriodicalId":54858,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136265506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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