The paper focuses on stiffness matrix computation for manipulators with passive joints, compliant actuators and flexible links. It proposes both explicit analytical expressions and an efficient recursive procedure that are applicable in the general case and allow obtaining the desired matrix either in analytical or numerical form. Advantages of the developed technique and its ability to produce both singular and non-singular stiffness matrices are illustrated by application examples that deal with stiffness modeling of two Stewart-Gough platforms.
Institut de Recherches en Communications et Cybernétique de Nantes（南特通信与控制研究所）；Ecole des Mines de Nantes（南特矿业学院）
The paper presents a new stiffness modeling method for overconstrained parallel manipulators with flexible links and compliant actuating joints. It is based on a multidimensional lumped-parameter model that replaces the link flexibility by localized 6-dof virtual springs that describe both translational/rotational compliance and the coupling between them. In contrast to other works, the method involves a FEA-based link stiffness evaluation and employs a new solution strategy of the kinetostatic equations for the unloaded manipulator configuration, which allows computing the stiffness matrix fo…
Laboratoire des Sciences du Numérique de Nantes (LS2N)（南特数字科学实验室）；Innopolis University（因诺波利斯大学）；IMT Atlantique Nantes（大西洋矿业电信学院南特校区）；Centre National de la Recherche Scientifique (CNRS)（法国国家科学研究中心）
The paper focuses on the stiffness analysis of multi-link serial planar manipulators, which may demonstrate nonlinear stiffness behavior under the compressive loading. Two important cases are considered, where the manipulator has either a straight or non-straight initial configuration. It was proved that in the first case the loading may cause the buckling if it exceeds some critical value, and the manipulator suddenly changes its straight shape and stiffness properties. For computing this critical force, a general eigenvalue-based technique was proposed that can be applied to any multi-link s…
Ecole des Mines de Nantes（南特矿业学院）；Institut de Recherches en Communications et en Cybernetique de Nantes（南特通信与控制研究所）
The paper presents a methodology to enhance the stiffness analysis of serial and parallel manipulators with passive joints. It directly takes into account the loading influence on the manipulator configuration and, consequently, on its Jacobians and Hessians. The main contributions of this paper are the introduction of a non-linear stiffness model for the manipulators with passive joints, a relevant numerical technique for its linearization and computing of the Cartesian stiffness matrix which allows rank-deficiency. Within the developed technique, the manipulator elements are presented as pse…
The paper focuses on the stiffness modeling of parallel manipulators composed of non-perfect serial chains, whose geometrical parameters differ from the nominal ones. In these manipulators, there usually exist essential internal forces/torques that considerably affect the stiffness properties and also change the end-effector location. These internal load-ings are caused by elastic deformations of the manipulator ele-ments during assembling, while the geometrical errors in the chains are compensated for by applying appropriate forces. For this type of manipulators, a non-linear stiffness modeli…
Institut de Recherche en Communications et en Cybernetique de Nantes（南特通信与控制论研究所）；Ecole des Mines de Nantes（南特国立高等矿业学校）
The paper presents a methodology to enhance the stiffness analysis of parallel manipulators with parallelogram-based linkage. It directly takes into account the influence of the external loading and allows computing both the non-linear ``load-deflection" relation and relevant rank-deficient stiffness matrix. An equivalent bar-type pseudo-rigid model is also proposed to describe the parallelogram stiffness by means of five mutually coupled virtual springs. The contributions of this paper are highlighted with a parallelogram-type linkage used in a manipulator from the Orthoglide family.
Ecole des Mines de Nantes（南特矿业学院）；Institut de Recherches en Communications et en Cybernetique de Nantes（南特通信与控制研究所）
The paper focuses on stiffness matrix computation for manipulators with passive joints. It proposes both explicit analytical expressions and an efficient recursive procedure that are applicable in general case and allow obtaining the desired matrix either in analytical or numerical form. Advantages of the developed technique and its ability to produce both singular and non-singular stiffness matrices are illustrated by application examples that deal with stiffness modeling of two Stewart-Gough platforms.
Institut de Recherches en Communications et Cybernetique de Nantes（南特通信与控制研究所）；Ecole des Mines de Nantes（南特矿业学院）
The paper focuses on the accuracy improvement of stiffness models for parallel manipulators, which are employed in high-speed precision machining. It is based on the integrated methodology that combines analytical and numerical techniques and deals with multidimensional lumped-parameter models of the links. The latter replace the link flexibility by localized 6-dof virtual springs describing both translational/rotational compliance and the coupling between them. There is presented detailed accuracy analysis of the stiffness identification procedures employed in the commercial CAD systems (incl…
Ecole des Mines de Nantes（南特矿业学院）；National Center for Scientific Research（国家科学研究中心）；University of Nantes（南特大学）
The paper focuses on the stiffness modeling of robotic manipulators with gravity compensators. The main attention is paid to the development of the stiffness model of a spring-based compensator located between sequential links of a serial structure. The derived model allows us to describe the compensator as an equivalent non-linear virtual spring integrated in the corresponding actuated joint. The obtained results have been efficiently applied to the stiffness modeling of a heavy industrial robot of the Kuka family.
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…
Laboratoire des Sciences du Numérique de Nantes (LS2N)（南特数字科学实验室）；IMT Atlantique（大西洋国立高等矿业电信学校）；Centre National de la Recherche Scientifique (CNRS)（法国国家科学研究中心）
The paper focuses on the stiffness modeling of a new type of compliant manipulator and its non-linear behavior while interacting with the environment. The manipulator under study is a serial mechanical structure composed of dualtriangle segments. The main attention is paid to the initial straight configuration which may suddenly change its shape under the loading. It was discovered that under the external loading such manipulator may have six equilibrium configurations but only two of them are stable. In the neighborhood of these configurations, the manipulator behavior was analyzed using the …
The paper focuses on the enhanced stiffness modeling of robotic manipulators by taking into account influence of the external force/torque acting upon the end point. It implements the virtual joint technique that describes the compliance of manipulator elements by a set of localized six-dimensional springs separated by rigid links and perfect joints. In contrast to the conventional formulation, which is valid for the unloaded mode and small displacements, the proposed approach implicitly assumes that the loading leads to the non-negligible changes of the manipulator posture and corresponding a…
Innopolis University（因诺波利斯大学）；Centre National de la Recherche Scientifique (CNRS)（法国国家科学研究中心）；Le Laboratoire des Sciences du Numérique de Nantes (LS2N)（南特数字科学实验室）；IMT Atlantique（大西洋国立高等工业技术与矿业学校）
The paper presents advancement of the matrix structural analysis technique (MSA) for stiffness modeling of robotic manipulators. In contrast to the classical MSA, it can be applied to both parallel and serial manipulators composed of flexible and rigid links connected by rigid, passive or elastic joints with multiple external loadings. The manipulator stiffness model is presented as a set of basic equations describing the link elasticities that are supplemented by a set of constraints describing connections between links. These equations are aggregated straightforwardly in a common linear syst…
Institut de Recherche en Communications et en Cybernétique de Nantes（南特通信与控制研究院）；École des Mines de Nantes（南特矿业学院）
The paper presents a methodology for the enhanced stiffness analysis of parallel manipulators with internal preloading in passive joints. It also takes into account influence of the external loading and allows computing both the non-linear "load-deflection" relation and the stiffness matrices for any given location of the end-platform or actuating drives. Using this methodology, it is proposed the kinetostatic control algorithm that allows to improve accuracy of the classical kinematic control and to compensate position errors caused by elastic deformations in links/joints due to the external/…
Saratoga High School（萨拉托加高中）；University of Michigan（密歇根大学）
We propose a mechanically simple and cheap design for a series elastic actuator with controllable stiffness. Such characteristics are necessary for animals for running, jumping, throwing, and manipulation, yet in robots, variable stiffness actuators are either complicated or mimicked at low bandwidth through feedback controllers. A robust and simple design is needed to build reliable and cheap robots with animal capabilities. The key insight of our design is attaching torsional springs to timing belts to create a variable stiffness linear spring. In an antagonistic pair, varying the distance b…
Ecole des Mines de Nantes（南特矿业学院）；Institut de Recherche en Communications et Cybernétique de Nantes（南特通信与控制论研究所）
The paper focuses on the calibration of elastostatic parameters of spatial anthropomorphic robots. It proposes a new strategy for optimal selection of the measurement configurations that essentially increases the efficiency of robot calibration. This strategy is based on the concept of the robot test-pose and ensures the best compliance error compensation for the test configuration. The advantages of the proposed approach and its suitability for practical applications are illustrated by numerical examples, which deal with calibration of elastostatic parameters of a 3 degrees of freedom anthrop…
IRCCyN (UMR CNRS 6597)（法国南特中央理工学院）；École des Mines de Nantes（南特矿业学院）
The paper presents a new stiffness modelling method for overconstrained parallel manipulators, which is applied to 3-d.o.f. translational mechanisms. It is based on a multidimensional lumped-parameter model that replaces the link flexibility by localized 6-d.o.f. virtual springs. In contrast to other works, the method includes a FEA-based link stiffness evaluation and employs a new solution strategy of the kinetostatic equations, which allows computing the stiffness matrix for the overconstrained architectures and for the singular manipulator postures. The advantages of the developed technique…
Institut de Recherches en Communications et Cybernetique de Nantes（南特通信与控制研究所）；Ecole des Mines de Nantes（南特矿业学院）
This paper focuses on the performance evaluation of the parallel manipulators for milling of composite materials. For this application the most significant performance measurements, which denote the ability of the manipulator for the machining are defined. In this case, optimal synthesis task is solved as a multicriterion optimization problem with respect to the geometric, kinematic, kinetostatic, elastostostatic, dynamic properties. It is shown that stiffness is an important performance factor. Previous models operate with links approximation and calculate stiffness matrix in the neighborhood…
The Stiffness of 3-PRS PM Across Parasitic and Orientational Workspace
School of Mechanical Engineering, Zhejiang University（浙江大学机械工程学院）；Robotics Research Center of Yuyao (Robotics Institute of Zhejiang University)（余姚机器人研究中心（浙江大学机器人研究院））；xR Lab（xR实验室）
A Modular, Tendon Driven Variable Stiffness Manipulator with Internal Routing for Improved Stability and Increased Payload Capacity
National Robotarium（国家机器人研究院）；Heriot Watt University（赫瑞瓦特大学）；Institute for Integrated Micro and Nano Systems（集成微纳系统研究所）；University of Edinburgh（爱丁堡大学）；Tough Cyberphysical AI Research Center (TCPAI)（硬核赛博物理人工智能研究中心）；Tohoku University（东北大学）；Senai Cimatec（塞奈西马泰克）
Indian Institute of Science（印度科学学院）；Robert Bosch Center for Cyber Physical Systems（罗伯特·博世信息物理系统研究中心）
Grabbing a manoeuvring target using drones is a challenging problem. This paper presents the design, development, and prototyping of a novel aerial manipulator for target interception. It is a single Degree of Freedom (DoF) manipulator with passive basket-type end-effector. The proposed design is energy efficient, light weight and suitable for aerial grabbing applications. The detailed design of the proposed manipulation mechanism and a novel in-flight extending propeller guard, is reported in this paper.
Indian Institute of Science（印度科学学院）；Robert Bosch Center for Cyber Physical Systems（罗伯特·博世网络物理系统中心）
In this paper, we present a novel passive single Degree-of-Freedom (DoF) manipulator design and its integration on an autonomous drone to capture a moving target. The end-effector is designed to be passive, to disengage the moving target from a flying UAV and capture it efficiently in the presence of disturbances, with minimal energy usage. It is also designed to handle target sway and the effect of downwash. The passive manipulator is integrated with the drone through a single Degree of Freedom (DoF) arm, and experiments are carried out in an outdoor environment. The rack-and-pinion mechanism…
Ecole des Mines de Nantes（南特矿业学院）；Institut de Recherches en Communications et Cybernétique de Nantes（南特通信与控制研究所）
The paper presents a new stiffness modelling method for multi-chain parallel robotic manipulators with flexible links and compliant actuating joints. In contrast to other works, the method involves a FEA-based link stiffness evaluation and employs a new solution strategy of the kinetostatic equations, which allows computing the stiffness matrix for singular postures and to take into account influence of the external forces. The advantages of the developed technique are confirmed by application examples, which deal with stiffness analysis of a parallel manipulator of the Orthoglide family
Ecole des Mines de Nantes（南特高等矿业学校）；Institut de Recherches en Communications et en Cybernetique de Nantes（南特通信与控制论研究所）
The paper presents an approach for the identification of elasto-static parameters of a robotic manipulator using the virtual experiments in a CAD environment. It is based on the numerical processing of the data extracted from the finite element analysis results, which are obtained for isolated manipulator links. This approach allows to obtain the desired stiffness matrices taking into account the complex shape of the links, couplings between rotational/translational deflections and particularities of the joints connecting adjacent links. These matrices are integral parts of the manipulator lum…
Institut de Recherche en Communications et Cybernétique de Nantes（南特通信与控制研究所）
The paper presents a new stiffness modelling method for overconstrained parallel manipulators, which is applied to 3-d.o.f. translational mechanisms. It is based on a multidimensional lumped-parameter model that replaces the link flexibility by localized 6-d.o.f. virtual springs. In contrast to other works, the method includes a FEA-based link stiffness evaluation and employs a new solution strategy of the kinetostatic equations, which allows computing the stiffness matrix for the overconstrained architectures and for the singular manipulator postures. The advantages of the developed technique…
Laboratoire des Sciences du Numérique de Nantes (LS2N), UMR CNRS 6004（南特数字科学实验室（法国国家科学研究中心UMR 6004））；Ecole Centrale Nantes（南特中央理工学院）；IMT Atlantique（大西洋电信学院）；Innopolis University（因诺波利斯大学）；Centre National de la Recherche Scientifique (CNRS)（法国国家科学研究中心）
The paper focuses on the mechanics of a compliant serial manipulator composed of new type of dual-triangle elastic segments. Both the analytical and numerical methods were used to find the manipulator stable and unstable equilibrium configurations, as well as to predict corresponding manipulator shapes. The stiffness analysis was carried on for both loaded and unloaded modes, the stiffness matrices were computed using the Virtual Joint Method (VJM). The results demonstrate that either buckling or quasi-buckling phenomenon may occur under the loading, if the manipulator corresponding initial co…
University of Modena and Reggio Emilia（摩德纳-雷焦艾米利亚大学）
Human-robot collaborative tasks foresee interactions between humans and robots with various degrees of complexity. Specifically, for tasks which involve physical contact among the agents, challenges arise in the modelling and control of such interaction. In this paper we propose a control architecture capable of ensuring a flexible and robustly stable physical human-robot interaction, focusing on a collaborative transportation task. The architecture is deployed onto a mobile manipulator, modelled as a whole-body structure, which aids the operator during the transportation of an unwieldy load. …
Co-optimizing Physical Reconfiguration Parameters and Controllers for an Origami-inspired Reconfigurable Manipulator
Colorado State University（科罗拉多州立大学）；University of Massachusetts Amherst（马萨诸塞大学阿默斯特分校）；Manning College of Information and Computer Sciences（曼宁信息与计算机科学学院）
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）
The ability to adapt and conform to angular and uneven surfaces improves the suction cup's performance in grasping and manipulation. However, in most cases, the adaptation costs lack of required stiffness for manipulation after surface attachment; thus, the ideal scenario is to have compliance during adaptation and stiffness after attachment to the surface. Nevertheless, most stiffness modulation techniques in suction cups require additional actuation. This article presents a new stiffness tunable suction cup that adapts to steep angular surfaces. Using granular jamming as a vacuum driven stif…
Modular Active Cell Robots (MACROs) are a design paradigm for modular robotic hardware that uses only two components, namely actuators and passive compliant joints. Under the MACRO approach, a large number of actuators and joints are connected to create mesh-like cellular robotic structures that can be actuated to achieve large deformation and shape-change. In this two-part paper, we study the importance of different possible mesh topologies within the MACRO framework. Regular and semi-regular tilings of the plane are used as the candidate mesh topologies and simulated using Finite Element Ana…
Ecole des Mines de Nantes（南特高等矿业学院）；Institut de Recherches en Communications et Cybernétique de Nantes（南特通信与控制研究所）
The paper presents a new stiffness modelling method for multi-chain parallel robotic manipulators with flexible links and compliant actuating joints. In contrast to other works, the method involves a FEA-based link stiffness evaluation and employs a new solution strategy of the kinetostatic equations, which allows computing the stiffness matrix for singular postures and to take into account influence of the internal forces. The advantages of the developed technique are confirmed by application examples, which deal with stiffness analysis of the Orthoglide manipulator.
University of Texas at Austin（德克萨斯大学奥斯汀分校）；Cornerstone Robotics Limited（基石机器人有限公司）；The Chinese University of Hong Kong（香港中文大学）；Johns Hopkins University（约翰斯·霍普金斯大学）
This paper addresses the problem of controlling a continuum manipulator (CM) in free or obstructed environments with no prior knowledge about the deformation behavior of the CM and the stiffness and geometry of the interacting obstructed environment. We propose a versatile data-driven priori-model-independent (PMI) control framework, in which various control paradigms (e.g. CM's position or shape control) can be defined based on the provided feedback. This optimal iterative algorithm learns the deformation behavior of the CM in interaction with an unknown environment, in real time, and then ac…
Czech Technical University in Prague（布拉格捷克理工大学）；Blue Danube Robotics GmbH（蓝多瑙河机器人有限公司）
Soft electronic skins are one of the means to turn an industrial manipulator into a collaborative robot. For manipulators that are already fit for physical human-robot collaboration, soft skins can make them safer. In this work, we study the after impact behavior of two collaborative manipulators (UR10e and KUKA LBR iiwa) and one classical industrial manipulator (KUKA Cybertech), in presence or absence of an industrial protective skin (AIRSKIN). In addition, we isolate the effects of the passive padding and the active contribution of the sensor to robot reaction. We present a total of 2250 col…
Institut de Recherches en Communications et Cybernétique de Nantes（南特通信与控制研究所）；École Centrale de Nantes（南特中央理工学院）；École des Mines de Nantes（南特矿业学院）；Université de Nantes（南特大学）；Université Laval（拉瓦尔大学）
This paper presents a parametric stiffness analysis of the Orthoglide, a 3-DOF translational Parallel Kinematic Machine. First, a compliant modeling of the Orthoglide is conducted based on an existing method. Then stiffness matrix is symbolically computed. This allows one to easily study the influence of the geometric design parameters on the matrix elements. Critical links are displayed. Cutting forces are then modeled so that static displacements of the Orthoglide tool during slot milling are symbolically computed. Influence of the geometric design parameters on the static displacements is c…
Ultra-slender Coaxial Antagonistic Tubular Robot for Ambidextrous Manipulation
West China Hospital of Medicine, Sichuan University（四川大学华西医学院）；Shien-Ming Wu School of Intelligent Engineering, South China University of Technology（华南理工大学伍舜明智能工程学院）；School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China（电子科技大学机械与电气工程学院）；School of Mechanical Engineering, Sichuan University（四川大学机械工程学院）；Centre for Artificial Intelligence and Robotics (CAIR) Hong Kong Institute of Science and Innovation, Chinese Academy of Sciences（中国科学院香港创新研究院人工智能与机器人中心）
Institut de Recherches en Communications et Cybernétique de Nantes (IRCCyN)（南特通信与控制研究所）；Ecole des Mines de Nantes（南特矿业学院）
This paper discusses the utility of using simple stiffness and vibrations models, based on the Jacobian matrix of a manipulator and only the rigidity of the actuators, whenever its geometry is optimised. In many works, these simplified models are used to propose optimal design of robots. However, the elasticity of the drive system is often negligible in comparison with the elasticity of the elements, especially in applications where high dynamic performances are needed. Therefore, the use of such a simplified model may lead to the creation of robots with long legs, which will be submitted to l…
University of California, Santa Cruz（加州大学圣克鲁兹分校）；NASA Ames Dynamic Tensegrity Robotics Lab（NASA艾姆斯动力张拉整体机器人实验室）；NASA-ARC Advanced Studies Laboratories（NASA艾姆斯研究中心高级研究实验室）；Stinger Ghaffarian Technologies（Stinger Ghaffarian Technologies公司）
Most traditional robotic mechanisms feature inelastic joints that are unable to robustly handle large deformations and off-axis moments. As a result, the applied loads are transferred rigidly throughout the entire structure. The disadvantage of this approach is that the exerted leverage is magnified at each subsequent joint possibly damaging the mechanism. In this paper, we present two lightweight, elastic, bio-inspired tensegrity robotics arms which mitigate this danger while improving their mechanism's functionality. Our solutions feature modular tensegrity structures that function similarly…
Starting from the definition of a stiffness matrix, the authors present a new formulation of the Cartesian stiffness matrix of parallel mechanisms. The proposed formulation is more general than any other stiffness matrix found in the literature since it can take into account the stiffness of the passive joints, it can consider additional compliances in the joints or in the links and it remains valid for large displacements. Then, the validity, the conservative property, the positive definiteness and the relation with other formulations of stiffness matrices are discussed theoretically. Finally…
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 …
