检索结果-内蒙古大学图书馆

arXiv 2018年

作者： Giftthaler, Markus Buchliy, Jonas Agile and Dexterous Robotics Lab Institute of Robotics and Intelligent Systems ETH Zürich Switzerland

This paper presents a state and state-input constrained variant of the discrete-time iterative Linear Quadratic Regulator (iLQR) algorithm, with linear time-complexity in the number of time steps. The approach is based on a projection of the control input onto the nullspace of the linearized constraints. We derive a fully constraint-compliant feedforward-feedback control update rule, for which we can solve efficiently with Riccati-style difference equations. We assume that the relative degree of all constraints in the discrete-time system model is equal to one, which often holds for robotics problems employing rigid-body dynamic models. Simulation examples, including a 6 DoF robotic arm, are given to validate and illustrate the performance of the method. Copyright © 2018, The Authors. All rights reserved.

关键词： Difference equations

来源：评论

学校读者我要写书评

暂无评论

Unified motion control for dynamic quadrotor maneuvers demonstrated on slung load and rotor failure tasks

Unified motion control for dynamic quadrotor maneuvers demon...

引用

IEEE International Conference on robotics and Automation (ICRA)

作者： Cédric de Crousaz Farbod Farshidian Michael Neunert Jonas Buchli Agile & Dexterous Robotics Lab Institute of Robotics and Intelligent Systems ETH Zürich Switzerland

ISBN: (纸本)9781479969241

In recent years impressive results have been presented illustrating the potential of quadrotors to solve challenging tasks. Generally, the derivation of the controllers involve complex analytical manipulation of the dynamics and are very specific to the task at hand. In addition, most approaches construct a trajectory and then design a stabilizing controller in a separate step, whereas a fully optimal solution requires finding both simultaneously. In this paper, a generalized approach is presented using an iterative optimal control algorithm. A series of complex tasks are thus solved using the same algorithm without the need for manual manipulation of the system dynamics, heuristic simplifications, or manual trajectory generation. First, aggressive maneuvers are performed by requiring the quadrotor to pass with a slung load through a window not high enough for the load to pass while hanging straight down. Second, go-to-goal tasks with single and double rotor failure are demonstrated. The adaptability and applicability of this unified approach to such diverse tasks with a nonlinear, underactuated, constrained, and in the case of the slung load, hybrid quadrotor systems is thus shown.

关键词： Rotors Trajectory Heuristic algorithms Load modeling Algorithm design and analysis Cost function Switches

来源：评论

学校读者我要写书评

暂无评论

Planning and execution of dynamic whole-body locomotion for a hydraulic quadruped on challenging terrain

Planning and execution of dynamic whole-body locomotion for ...

引用

IEEE International Conference on robotics and Automation (ICRA)

作者： Alexander W. Winkler Carlos Mastalli Ioannis Havoutis Michele Focchi Darwin G. Caldwell Claudio Semini Department of Advanced Robotics Istituto Italiano di Tecnologia Genova Italy Agile & Dexterous Robotics Lab Institute of Robotics and Intelligent Systems ETH Zurich Switzerland

We present a framework for dynamic quadrupedal locomotion over challenging terrain, where the choice of appropriate footholds is crucial for the success of the behaviour. We build a model of the environment on-line and on-board using an efficient occupancy grid representation. We use Any-time-Repairing A* (ARA*) to search over a tree of possible actions, choose a rough body path and select the locally-best footholds accordingly. We run a n-step lookahead optimization of the body trajectory using a dynamic stability metric, the Zero Moment Point (ZMP), that generates natural dynamic whole-body motions. A combination of floating-base inverse dynamics and virtual model control accurately executes the desired motions on an actively compliant system. Experimental trials show that this framework allows us to traverse terrains at nearly 6 times the speed of our previous work, evaluated over the same set of trials.

关键词： Dynamics Trajectory Acceleration Planning Vehicle dynamics Legged locomotion

来源：评论

学校读者我要写书评

暂无评论

Automatic Differentiation of Rigid Body Dynamics for Optimal Control and Estimation

arXiv

引用

arXiv 2017年

作者： Giftthaler, Markus Neunert, Michael Stäuble, Markus Frigerio, Marco Semini, Claudio Buchli, Jonas Agile & Dexterous Robotics Lab Institute of Robotics and Intelligent Systems ZürichETH Switzerland Dept. of Advanced Robotics Istituto Italiano di Tecnologia Genova Italy

Many algorithms for control, optimization and estimation in robotics depend on derivatives of the underlying system dynamics, e.g. to compute linearizations, sensitivities or gradient directions. However, we show that when dealing with Rigid Body Dynamics, these derivatives are difficult to derive analytically and to implement efficiently. To overcome this issue, we extend the modelling tool ‘RobCoGen’ to be compatible with Automatic Differentiation. Additionally, we propose how to automatically obtain the derivatives and generate highly efficient source code. We highlight the flexibility and performance of the approach in two application examples. First, we show a Trajectory Optimization example for the quadrupedal robot HyQ, which employs auto-differentiation on the dynamics including a contact model. Second, we present a hardware experiment in which a 6 DoF robotic arm avoids a randomly moving obstacle in a go-to task by fast, dynamic replanning. This paper is an extended version of [1]. Copyright © 2017, The Authors. All rights reserved.

关键词： Aerodynamics

来源：评论

学校读者我要写书评

暂无评论

Planning and execution of dynamic whole-body locomotion for a hydraulic quadruped on challenging terrain

arXiv

引用

arXiv 2019年

作者： Winkler, Alexander W. Mastalli, Carlos Havoutis, Ioannis Focchi, Michele Caldwell, Darwin G. Semini, Claudio Department of Advanced Robotics Istituto Italiano di Tecnologia via Morego 30 Genova16163 Italy Agile & Dexterous Robotics Lab Institute of Robotics and Intelligent Systems ETH Zurich Switzerland

— We present a framework for dynamic quadrupedal locomotion over challenging terrain, where the choice of appropriate footholds is crucial for the success of the behaviour. We build a model of the environment on-line and on-board using an efficient occupancy grid representation. We use Any-time-Repairing A* (ARA*) to search over a tree of possible actions, choose a rough body path and select the locally-best footholds accordingly. We run a n-step lookahead optimization of the body trajectory using a dynamic stability metric, the Zero Moment Point (ZMP), that generates natural dynamic whole-body motions. A combination of floating-base inverse dynamics and virtual model control accurately executes the desired motions on an actively compliant system. Experimental trials show that this framework allows us to traverse terrains at nearly 6 times the speed of our previous work, evaluated over the same set of trials. Copyright © 2019, The Authors. All rights reserved.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Nonlinear disturbance attenuation control of hydraulic robotics

arXiv

引用

arXiv 2018年

作者： Lu, Peng Sandy, Timothy Buchli, Jonas Interdisciplinary Division of Aeronautical and Aviation Engineering Hong Kong Polytechnic University Hong Kong Agile & Dexterous Robotics Lab at the Institute of Robotics and Intelligent Systems ETH Zürich Switzerland

This paper presents a novel nonlinear disturbance rejection control for hydraulic robots. This method requires two third-order filters as well as inverse dynamics in order to estimate the disturbances. All the parameters for the third-order filters are pre-defined. The proposed method is nonlinear, which does not require the linearization of the rigid body dynamics. The estimated disturbances are used by the nonlinear controller in order to achieve disturbance attenuation. The performance of the proposed approach is compared with existing approaches. Finally, the tracking performance and robustness of the proposed approach is validated extensively on real hardware by performing different tasks under either internal or both internal and external disturbances. The experimental results demonstrate the robustness and superior tracking performance of the proposed approach. Copyright © 2018, The Authors. All rights reserved.

关键词： Disturbance rejection

来源：评论

学校读者我要写书评

暂无评论

Adaptive Unscented Kalman Filter-based Disturbance Rejection With Application to High Precision Hydraulic Robotic Control

Adaptive Unscented Kalman Filter-based Disturbance Rejection...

引用

2019 IEEE/RSJ International Conference on intelligent Robots and systems (IROS)

作者： Peng Lu Timothy Sandy Jonas Buchli Interdisciplinary Division of Aeronautical and Aviation Engineering Hong Kong Polytechnic University HKSAR China Agile & Dexterous Robotics Lab Institute of Robotics and Intelligent Systems ETH Zürich Switzerland

This paper presents a novel nonlinear disturbance rejection approach for high precision model-based control of hydraulic robots. While most disturbance rejection approaches make use of observers, we propose a novel adaptive Unscented Kalman Filter to estimate the disturbances in an unbiased minimum-variance sense. The filter is made adaptive such that there is no need to tune the covariance matrix for the disturbance estimation. Furthermore, whereas most model-based control approaches require the linearization of the system dynamics, our method is nonlinear which means that no linearization is required. Through extensive simulations as well as real hardware experiments, we demonstrate that our proposed approach can achieve high precision tracking and can be readily applied to most robotic systems even in the presence of uncertainties and external disturbances. The proposed approach is also compared to existing approaches which demonstrates its superior tracking performance.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Design, development and experimental assessment of a robotic end-effector for non-standard concrete applications

Design, development and experimental assessment of a robotic...

引用

IEEE International Conference on robotics and Automation (ICRA)

作者： Nitish Kumar Norman Hack Kathrin Doerfler Alexander Nikolas Walzer Gonzalo Javier Rey Fabio Gramazio Matthias Daniel Kohler Jonas Buchli The Agile & Dexterous Robotics Lab The Institute of Robotics and Intelligent Systems ETH Zurich Switzerland The Chair of Architecture and Digital Fabrication The Institute of Technology in Architecture ETH Zurich Switzerland Gonzalo Javier Rey is with Moog Inc

Despite the recent advances in, and the adoption of robotic technologies in the construction industry, the architectural processes which demand a high degree of geometric freedom still remain largely labour intensive and manual. This is due to the inherent difficulties in robotizing the current implementation of such processes coupled with the lack of alternate robotic technologies. A specific example, which is also the focus of this paper, is that of building a steel reinforced concrete structure, with varying curvature or cross-section. This process still remains rather manual and requires extensive support of customized form-work. In this paper, first we describe an alternate novel robotic fabrication process for building steel wire meshes which act as both reinforcement and formwork. The robotization of such a process is discussed with the use of a previously developed mobile robotic system. Based on the specifications derived from the process, design of a novel custom designed robotic end-effector, enabling this process, is detailed. Automation of the full robotic system comprising the mobile robotic system and the robotic end-effector is discussed from simulation to control. Through experimental evaluation of the robotic system, we demonstrate the ability to fully automate the construction of non-standard steel reinforced steel meshes of varying curvature and cell sizes.

关键词： Wires Steel Concrete Service robots Fabrication Three-dimensional displays

来源：评论

学校读者我要写书评

暂无评论

Mobile robotic fabrication at 1:1 scale: the In situ Fabricator

引用

Construction robotics 2017年第1期1卷 3-14页

作者： Markus Giftthaler Timothy Sandy Kathrin Dörfler Ian Brooks Mark Buckingham Gonzalo Rey Matthias Kohler Fabio Gramazio Jonas Buchli Agile & Dexterous Robotics Lab ETH Zürich Institute of Robotics and Intelligent Systems Zürich Switzerland ETH Zürich Chair of Architecture and Digital Fabrication Zürich Switzerland Moog Inc. Buffalo USA Renishaw PLC. Gloucester UK

This paper presents the concept of an In situ Fabricator, a mobile robot intended for on-site manufacturing, assembly and digital fabrication. We present an overview of a prototype system, its capabilities, and highlight the importance of high-performance control, estimation and planning algorithms for achieving desired construction goals. Next, we detail on two architectural application scenarios: first, building a full-size undulating brick wall, which required a number of repositioning and autonomous localisation manoeuvres. Second, the mesh mould concrete process, which shows that an In situ Fabricator in combination with an innovative digital fabrication tool can be used to enable completely novel building technologies. Subsequently, important limitations of our approach are discussed. Based on that, we identify the need for a new type of robotic actuator, which facilitates the design of novel full-scale construction robots. We provide brief insight into the development of this actuator and conclude the paper with an outlook on the next-generation In situ Fabricator, which is currently under development.

关键词：

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：