A Comparative Study on 2-DOF Variable Stiffness Mechanisms
Universität Bremen - AG Robotik（不来梅大学 - 机器人工作组）；DFKI Bremen - Robotics Innovation Center（德国人工智能研究中心不来梅分所 - 机器人创新中心）；Johannes Kepler University, Linz（约翰内斯·开普勒大学林茨）
Christoph Stoeffler, Shivesh Kumar, Andreas Müller
备注：
This is a pre-print of the following chapter: C. Stoeffler, S. Kumar, A. Müller, A Comparative Study on 2-DOF Variable Stiffness Mechanisms, published in Advances in Robot Kinematics 2020, edited by Lenarčič J., Siciliano B., 2020, Springer reproduced with permission of Springer Nature. The final authenticated version is available online at: https://doi.org/10.1007/978-3-030-50975-0_1
Based on the idea of variable stiffness mechanisms, a variety of such mechanisms is shown in this work. Specifically, 2-DOF parallel kinematic machines equipped with redundant actuators and non-linear springs in the actuated joints are presented and a comparative overview is drawn. Accordingly, a general stiffness formulation in task space of all mechanisms is given. Under fixed geometric parameters, optimization of task space stiffness is carried out on the designs comprising all kinematic solutions. Finally, a stiffness metric is introduced that allows a quantitative comparison of the given mechanism designs. This gives rise to design guidelines for engineers but also shows an interesting outline for future applications of variable stiffness mechanisms.
The present project deals with the elastostatic modeling and calibration experiment of spacial industrial manipulators using an optimal selection of measurements pose, for the calibration procedure, the optimal pose selection aims to the efficiency improvement of identification procedure for serial manipulators which reduces noise impact on the parameters identification precision, it is usually used for planar manipulators, our work is mainly to extend the approach for a more complicated manipulator in 3D space using a wise decomposition of the spacial manipulator into a set of serial sub-chai…
Institut de Recherche en Communications et Cybernétique de Nantes（南特通信与控制论研究所）；INRIA Sophia-Antipolis（法国国家信息与自动化研究所索菲亚-安蒂波利斯分院）
This paper addresses the workspace analysis of two 3-DOF translational parallel mechanisms designed for machining applications. The two machines features three fixed linear joints. The joint axes of the first machine are orthogonal whereas these of the second are parallel. In both cases, the mobile platform moves in the Cartesian $x-y-z$ space with fixed orientation. The workspace analysis is conducted on the basis of prescribed kinetostatic performances. Interval analysis based methods are used to compute the dextrous workspace and the largest cube enclosed in this workspace.
Institut de Recherches en Communications et Cybernétique de Nantes（南特通信与控制研究所）；CNRS（法国国家科学研究中心）；Ecole Centrale de Nantes（南特中央理工学院）；Université de Nantes（南特大学）；Ecole des Mines de Nantes（南特矿业学院）
Parallel Kinematic Mechanisms (PKM) are interesting alternative designs for machine tools. A design method based on velocity amplification factors analysis is presented in this paper. The comparative study of two simple two-degree-of-freedom PKM dedicated to machining applications is led through this method: the common desired properties are the largest square Cartesian workspace for given kinetostatic performances. The orientation and position of the Cartesian workspace are chosen to avoid singularities and to produce the best ratio between Cartesian workspace size and mechanism size. The mac…
Institut de Recherche en Communications et Cybernétique de Nantes（南特通信与控制研究所）；Université Laval（拉瓦尔大学）；CNRS（法国国家科学研究中心）；École Centrale de Nantes（南特中央理工学院）；Université de Nantes（南特大学）；École des Mines de Nantes（南特矿业学院）
Parallel kinematic mechanisms are interesting alternative designs for machining applications. Three 2-DOF parallel mechanism architectures dedicated to machining applications are studied in this paper. The three mechanisms have two constant length struts gliding along fixed linear actuated joints with different relative orientation. The comparative study is conducted on the basis of a same prescribed Cartesian workspace for the three mechanisms. The common desired workspace properties are a rectangular shape and given kinetostatic performances. The machine size of each resulting design is used…
By learning Variable Impedance Control policy, robot assistants can intelligently adapt their manipulation compliance to ensure both safe interaction and proper task completion when operating in human-robot interaction environments. In this paper, we propose a DMP-based framework that learns and generalizes variable impedance manipulation skills from human demonstrations. This framework improves robots$'$ adaptability to environment changes(i.e. the weight and shape changes of grasping object at the robot end-effector) and inherits the efficiency of demonstration-variance-based stiffness estim…
Loss of upper extremity motor control and function is an unremitting symptom in post-stroke patients. This would impose hardships on accomplishing their daily life activities. Supernumerary robotic limbs (SRLs) were introduced as a solution to regain the lost Degrees of Freedom (DoFs) by introducing an independent new limb. The actuation systems in SRL can be categorized into rigid and soft actuators. Soft actuators have proven advantageous over their rigid counterparts through intrinsic safety, cost, and energy efficiency. However, they suffer from low stiffness, which jeopardizes their accur…
Jeonbuk National University（全北国立大学）；University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）
This paper presents a haptic interface with modular linear actuators which can address limitations of conventional devices based on rotatory joints. The proposed haptic interface is composed of parallel linear actuators that provide high backdrivability and small inertia. The performance of the haptic interface is compared with the conventional mechanisms in terms of force capability, reflected inertia, and structural stiffness. High stiffness, large range of motion with high force capability are achieved with the proposed mechanism, which are in trade-off relationships in traditional haptic i…
For the majority of tasks performed by traditional serial robot arms, such as bin picking or pick and place, only two or three degrees of freedom (DOF) are required for motion; however, by augmenting the number of degrees of freedom, further dexterity of robot arms for multiple tasks can be achieved. Instead of increasing the number of joints of a robot to improve flexibility and adaptation, which increases control complexity, weight, and cost of the overall system, malleable robots utilise a variable stiffness link between joints allowing the relative positioning of the revolute pairs at each…
We present an approach to overcoming challenges in dynamical dexterity for robots through tunable origami structures. Our work leverages a one-parameter family of flat sheet crease patterns that folds into origami bellows, whose axial compliance can be tuned to select desired stiffness. Concentrically arranged cylinder pairs reliably manifest additive stiffness, extending the tunable range by nearly an order of magnitude and achieving bulk axial stiffness spanning 200-1500 N/m using 8 mil thick polyester-coated paper. Accordingly, we design origami energy-storing springs with a stiffness of 10…
Institut de Recherche en Cybernétique de Nantes (IRCyN)（南特控制论研究所）；McGill University（麦吉尔大学）
This paper focuses on the kinematic properties of a new three-degree-of-freedom hybrid manipulator. This manipulator is obtained by adding in series to a five-bar planar mechanism (similar to the one studied by Bajpai and Roth) a third revolute passing through the line of centers of the two actuated revolute joints of the above linkage. The resulting architecture is hybrid in that it has both serial and parallel links. Fully-parallel manipulators are known for the existence of particularly undesirable singularities (referred to as parallel singularities) where control is lost [4] and [6]. On t…
Soft robotic systems offer benefits over traditional rigid systems through reduced contact trauma with soft tissues and by enabling access through tortuous paths in minimally invasive surgery. However, the inherent deformability of soft robots places both a greater onus on accurate modelling of their shape, and greater challenges in realising intraoperative shape sensing. Herein we present a proprioceptive (self-sensing) soft actuator, with an electrically conductive working fluid. Electrical impedance measurements from up to six electrodes enabled tomographic reconstructions using Electrical …
ATDM:An Anthropomorphic Aerial Tendon-driven Manipulator with Low-Inertia and High-Stiffness
Research Institute of Intelligent Control and Systems, Harbin Institute of Technology（哈尔滨工业大学智能控制与系统研究所）；Peng Cheng Laboratory（鹏城实验室）；Ningbo Institute of Intelligent Equipment Technology Co., Ltd.（宁波智能装备技术研究院有限公司）
Design, Dynamic Modeling and Control of a 2-DOF Robotic Wrist Actuated by Twisted and Coiled Actuators
College of Advanced Manufacturing and Robotics（先进制造与机器人学院）；State Key Laboratory of Turbulence and Complex Systems（湍流与复杂系统国家重点实验室）；Peking University（北京大学）；Department of Electrical and Computer Engineering（电气与计算机工程系）
In-situ aeroengine maintenance works are highly beneficial as it can significantly reduce the current maintenance cycle which is extensive and costly due to the disassembly requirement of engines from aircrafts. However, navigating in/out via inspection ports and performing multi-axis movements with end-effectors in constrained environments (e.g. combustion chamber) are fairly challenging. A novel extra-slender (diameter-to-length ratio <0.02) dual-stage continuum robot (16 degree-of-freedom) is proposed to navigate in/out confined environments and perform required configuration shapes for fur…
Belarusian State University of Informatics and Radioelectronics（白俄罗斯信息与无线电电子大学）；Institut de Recherche en Communications et Cybernétique de Nantes（南特通信与控制研究所）；CNRS（法国国家科学研究中心）；École Centrale de Nantes（南特中央理工学院）；Université de Nantes（南特大学）；École des Mines de Nantes（南特矿业学院）
The paper addresses the geometric synthesis of Orthoglide-type mechanism, a family of 3-DOF parallel manipulators for rapid machining applications, which combine advantages of both serial mechanisms and parallel kinematic architectures. These manipulators possess quasi-isotropic kinematic performances and are made up of three actuated fixed prismatic joints, which are mutually orthogonal and connected to a mobile platform via three parallelogram chains. The platform moves in the Cartesian space with fixed orientation, similar to conventional XYZ-machine. Three strategies have been proposed to …
