检索结果-内蒙古大学图书馆

IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Wyatt Ubellacker Aaron D. Ames Departments of Control and Dynamical Systems Mechanical and Civil Engineering California Institute of Technology Pasadena CA USA

ISBN: (数字)9798350377705

ISBN: (纸本)9798350377712

Estimating regions of attraction (ROAs) of dynamical systems is critical for understanding the operational bounds within which a system will converge to a desired state. In this paper, we introduce a neural network-based approach to approximating ROAs that leverages labeled data generated by offline sampling and simulation of initial conditions, with labels determined by flow membership in an "explicit region of attraction." This framework is designed to estimate ROAs with a level of precision suitable for integration into a motion primitive transition framework as conditions to switch between candidate primitive behaviors. To account for gaps between the simulated environment and the real world, online learning is employed; this refines the offline-learned model of the ROA based on observed discrepancies between predicted and actual system behaviors. We validate this methodology on a quadrupedal robot, demonstrating that our ROA estimates can effectively model regions of attraction for a high-dimensional system. We show this for multiple primitive behaviors and in environments different from the training data. The outcomes highlight the usefulness of our method in estimating regions of attraction and informing transition conditions between primitive behaviors.

关键词： Training Neural networks Training data Switches Predictive models Robot sensing systems Data models Quadrupedal robots dynamical systems Intelligent robots

来源：评论

学校读者我要写书评

暂无评论

Approximating Regions of Attraction via Flow-control Barrier Functions and Constrained Polytope Expansion

Approximating Regions of Attraction via Flow-Control Barrier...

引用

American control Conference (ACC)

作者： Wyatt Ubellacker Noel Csomay-Shanklin Aaron D. Ames Dept. of Control and Dynamical Systems Mechanical and Civil Engineering California Institute of Technology Pasadena CA USA

ISBN: (数字)9798350382655

ISBN: (纸本)9798350382662

Regions of attraction are a fundamental and extensively researched concept in control theory—their accurate characterization is essential to establishing the robustness of equilibria to perturbations since they quantify the set of initial conditions that converge to a given stable equilibrium point. They are of special interest for nonlinear dynamical systems, as they often lack analytical solutions and therefore require the use of numerical methods to obtain useful approximations. In this paper, we leverage recent results in control barrier function theory to propose a novel method to approximate regions of attraction about stable fixed points. First, we establish connections between the region of attraction and the idea of an “explicit region of attraction” for dynamical systems. This motivates an extension of control barrier functions termed flow-control barrier functions $(\phi-\boldsymbol{CBF})$ , and we introduce the idea of an “auxiliary dynamical system” connected to a target system via a $\phi-\mathbf{CBF}$ . We construct a time-varying polytope governed by expansion dynamics, but bounded to lie within the desired region of attraction. The main result establishes that as the number of polytope vertices increases, this polytope approximates the region of attraction with arbitrary accuracy. We illustrate our method through various compelling examples.

关键词： Accuracy Limiting Scalability Perturbation methods Heuristic algorithms Robustness Nonlinear dynamical systems

来源：评论

学校读者我要写书评

暂无评论

Hierarchical Event-Triggered systems: Safe Learning of Quasi-Optimal Deadline Policies 63

Hierarchical Event-Triggered Systems: Safe Learning of Quasi...

引用

63rd IEEE Conference on Decision and control, CDC 2024

作者： Ong, Pio Mazo, Manuel Ames, Aaron D. California Institute of Technology Department of Mechanical and Civil Engineering PasadenaCA91125 United States Delft University of Technology Delft Center for Systems and Control Faculty of Mechanical Engineering Netherlands

ISBN: (纸本)9798350316339

We present a hierarchical architecture to improve the efficiency of event-triggered control (ETC) in reducing resource consumption. This paper considers event-triggered systems generally as an impulsive control system in which the objective is to minimize the number of impulses. Our architecture recognizes that traditional ETC is a greedy strategy towards optimizing average inter-event times and introduces the idea of a deadline policy for the optimization of long-term discounted inter-event times. A lower layer is designed employing event-triggered control to guarantee the satisfaction of control objectives, while a higher layer implements a deadline policy designed with reinforcement learning to improve the discounted inter-event time. We apply this scheme to the control of an orbiting spacecraft, showing superior performance in terms of actuation frequency reduction with respect to a standard (one-layer) ETC while maintaining safety guarantees. © 2024 IEEE.

关键词： Orbits

来源：评论

学校读者我要写书评

暂无评论

Robust Locomotion on Legged Robots through Planning on Motion Primitive Graphs

Robust Locomotion on Legged Robots through Planning on Motio...

引用

IEEE International Conference on Robotics and Automation (ICRA)

作者： Wyatt Ubellacker Aaron D. Ames Departments of Control and Dynamical Systems Mechanical and Civil Engineering California Institute of Technology Pasaden CA USA

The functional demands of robotic systems often require completing various tasks or behaviors under the effect of disturbances or uncertain environments. Of increasing interest is the autonomy for dynamic robots, such as multirotors, motor vehicles, and legged platforms. Here, disturbances and environmental conditions can have significant impact on the successful performance of the individual dynamic behaviors, referred to as “motion primitives”. Despite this, robustness can be achieved by switching to and transitioning through suitable motion primitives. This paper contributes such a method by presenting an abstraction of the motion primitive dynamics and a corresponding”motion primitive transfer function”. From this, a mixed discrete and continuous “motion primitive graph” is constructed, and an algorithm capable of online search of this graph is detailed. The result is a framework capable of realizing holistic robustness on dynamic systems. This is experimentally demonstrated for a set of motion primitives on a quadrupedal robot, subject to various environmental and intentional disturbances.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Deep-Learning-based damage detection of an experimentally tested full-scale wind turbine blade 11

Deep-Learning-based damage detection of an experimentally te...

引用

11th European Workshop on Structural Health Monitoring, EWSHM 2024

作者： Varouxis, Theodoros Dertimanis, Vasilis Abdallah, Imad Chatzi, Eleni Pakrashi, Vikram Malekjafarian, Abdollah Structural Dynamics and Assessment Laboratory School of Civil Engineering University College Dublin Dublin Ireland Department of Civil Environmental and Geomatic Engineering ETH Zurich Zurich Switzerland UCD Centre for Mechanics Dynamical Systems and Risk Laboratory School of Mechanical and Materials Engineering University College Dublin Dublin Ireland

Reducing the operation and maintenance (O&M) costs of wind farms can foster adoption of environmentally sustainable and cost-effective energy sources. O&M costs in Wind Turbines can account up to 35% of the turbine's total levelized cost per KWh, with a large portion attributed to that for wind turbine blades (WTB). In the present study, an experimental campaign for fatigue damage progression monitoring is presented. After subjecting the WTB to cyclic loading, an artificial transverse crack was introduced in the trailing edge (TE).The dynamic response of the blade to three different excitation schemes - white noise, white noise with the inclusion of a fundamental sinusoidal component and a frequency sweep- is obtained via the use of accelerometers, strain gauges and a real-time deflection monitoring system. These tests yielded generated 4 different health states, the initial healthy and 3 damaged states. The progressive damage is presented using frequency response functions (FRFs),while a simple deep-learning damage detection framework is developed. A conventional autoencoder (AE) is trained using the Frequency Response Functions (FRFs) corresponding to the blade's healthy state;then, an unsupervised damage detection algorithm is formulated using the AE. © 2024 11th European Workshop on Structural Health Monitoring, EWSHM 2024. All rights reserved.

关键词： Fatigue damage

来源：评论

学校读者我要写书评

暂无评论

Performance Analysis and Flexible control of a Novel Ball Double-screw Hydraulic Robot Knee Joint

引用

Journal of Bionic engineering 2023年第5期20卷 2147-2163页

作者： Jie Shao Yongming Bian Meng Yang Guangjun Liu School of Mechanical Engineering Tongji UniversityShanghai201804China State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou310027China Department of Control Science and Engineering Tongji UniversityShanghai201804China National Engineering Technology Research Center for Prefabrication Construction in Civil Engineering Tongji UniversityShanghai200092China

Focusing on the ball double-screw hydraulic knee joint as the research object,this paper analyzes the load driving performance of the hydraulic knee *** the posture data of the human body such as walking,squatting and landing buffer as initial learning objects,motion features are *** simplifying the trajectories of different motion actions into key feature control points and flexible trajectory fitting,the trajectory of joint actions is *** method can realize the adaptability of the hydraulic robot knee joint in different movements,and take the flexible action as the optimization goal under the condition of ensuring the movement performance,so as to reduce the damage to the knee joint caused by the foot impact in *** simulation model was built by Adams and Matlab to complete the performance analysis and motion optimization experiment of the knee *** simulation results show that the foot impact force of the experimental model decreases gradually through ***,the method is applied to the hydraulic joint experimental prototype to prove its load capacity and flexible motion control performance.

关键词： Bionic robot Ball double-screw hydraulic joint Robot knee joint Performance analysis Humanoid motion control Flexible control

来源：评论

学校读者我要写书评

暂无评论

Reduced-Order Model Guided Contact-Implicit Model Predictive control for Humanoid Locomotion

arXiv

引用

arXiv 2025年

作者： Esteban, Sergio A. Kurtz, Vince Ghansah, Adrian B. Ames, Aaron D. The Department of Mechanical and Civil Engineering California Institute of Technology PasadenaCA91125 United States The Department of Control and Dynamical Systems California Institute of Technology PasadenaCA91125 United States

Humanoid robots have great potential for real-world applications due to their ability to operate in environments built for humans, but their deployment is hindered by the challenge of controlling their underlying high-dimensional nonlinear hybrid dynamics. While reduced-order models like the Hybrid Linear Inverted Pendulum (HLIP) are simple and computationally efficient, they lose whole-body expressiveness. Meanwhile, recent advances in Contact-Implicit Model Predictive control (CI-MPC) enable robots to plan through multiple hybrid contact modes, but remain vulnerable to local minima and require significant tuning. We propose a control framework that combines the strengths of HLIP and CI-MPC. The reduced-order model generates a nominal gait, while CIMPC manages the whole-body dynamics and modifies the contact schedule as needed. We demonstrate the effectiveness of this approach in simulation with a novel 24 degree-of-freedom humanoid robot: Achilles. Our proposed framework achieves rough terrain walking, disturbance recovery, robustness under model and state uncertainty, and allows the robot to interact with obstacles in the environment, all while running online in real-time at 50 Hz. Copyright © 2025, The Authors. All rights reserved.

关键词： Model predictive control

来源：评论

学校读者我要写书评

暂无评论

A novel electron-phonon coupling thermoelasticity with Burgers electronic heat transfer

引用

Applied Mathematics and Mechanics(English Edition) 2023年第11期44卷 1927-1940页

作者： Hua WU Xinyi LI Yajun YU Zichen DENG School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical UniversityXi'an 710072China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong UniversityXi'an 710049China

The electron-phonon interaction can reveal the microscopic mechanism of heat transfer in *** two-step heat conduction considering electron-phonon interaction has become an effective theoretical model for extreme environments,such as micro-scale and ultrafast *** this work,the two-step heat transfer model is further extended by considering the Burgers heat conduction model with the secondorder heat flux rate for ***,a novel generalized electron-phonon coupling thermoelasticity is proposed with the Burgers electronic heat ***,the problem of one-dimensional semi-infinite copper strip subject to a thermal shock at one side is studied by the Burgers two-step(BTS)*** thermoelastic analytical solutions are systematically derived in the Laplace domain,and the numerical Laplace inversion method is adopted to obtain the transient *** new model is compared with the parabolic two-step(PTS)model and the hyperbolic two-step(HTS)*** results show that in ultrafast heating,the BTS model has the same wave front jump as the HTS *** present model has the faster wave speed,and predicts the bigger disturbed regions than the HTS *** deeply,all two-step models also have the faster wave speeds than one-step *** work may benefit the theoretical modeling of ultrafast heating of metals.

关键词： Burgers heat transfer electron-phonon coupling two-step generalized thermoelasticity

来源：评论

学校读者我要写书评

暂无评论

Robust Bipedal Locomotion: Leveraging Saltation Matrices for Gait Optimization

Robust Bipedal Locomotion: Leveraging Saltation Matrices for...

引用

IEEE International Conference on Robotics and Automation (ICRA)

作者： Maegan Tucker Noel Csomay-Shanklin Aaron D. Ames Department of Mechanical and Civil Engineering California Institute of Technology Pasadena CA Department of Control and Dynamical Systems California Institute of Technology Pasadena CA

The ability to generate robust walking gaits on bipedal robots is key to their successful realization on hard-ware. To this end, this work extends the method of Hybrid Zero Dynamics (HZD) – which traditionally only accounts for locomotive stability via periodicity constraints under perfect impact events – through the inclusion of the saltation matrix with a view toward synthesizing robust walking gaits. By jointly minimizing the norm of the extended saltation matrix and the torque of the robot directly in the gait generation process, we demonstrate that the synthesized gaits are more robust than gaits generated with either term alone; these results are shown in simulation and on hardware for the AMBER-3M planar biped and the Atalante lower-body exoskeleton (both with and without a human subject). The end result is experimental validation that combining saltation matrices with HZD methods produces more robust bipedal walking in practice.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Synthesizing Robust Walking Gaits via Discrete-Time Barrier Functions with Application to Multi-Contact Exoskeleton Locomotion

Synthesizing Robust Walking Gaits via Discrete-Time Barrier ...

引用

IEEE International Conference on Robotics and Automation (ICRA)

作者： Maegan Tucker Kejun Li Aaron D. Ames School of Electrical and Computer Engineering and the Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta GA Department of Computation and Neural Systems California Institute of Technology Pasadena CA Department of Mechanical and Civil Engineering and the Department of Control and Dynamical Systems California Institute of Technology Pasadena CA

ISBN: (数字)9798350384574

ISBN: (纸本)9798350384581

Successfully achieving bipedal locomotion remains challenging due to real-world factors such as model uncertainty, random disturbances, and imperfect state estimation. In this work, we propose a novel metric for locomotive robustness – the estimated size of the hybrid forward invariant set associated with the step-to-step dynamics. Here, the forward invariant set can be loosely interpreted as the region of attraction for the discrete-time dynamics. We illustrate the use of this metric towards synthesizing nominal walking gaits using a simulation-in-the-loop learning approach. Further, we leverage discrete-time barrier functions and a sampling-based approach to approximate sets that are maximally forward invariant. Lastly, we experimentally demonstrate that this approach results in successful locomotion for both flat-foot walking and multi-contact walking on the Atalante lower-body exoskeleton.

关键词： Legged locomotion Measurement Uncertainty Exoskeletons Robustness State estimation Robots

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：