Stability of control system in handling of a flexible object by rigid arm robots

科研費報告書収録論文(課題番号:07455416・基盤研究(B)(2)・H7～H9/研究代表者:内山, 勝/フレキシブル双腕ロボットの協調制御に関する研究

A Microfabricated Planar Digital Microrobot for Precise Positioning Based on Bistable Modules

International audienceSize reduction is a constant objective in new technologies, for which very accurate devices are needed when manipulating sub-millimetric objects. A new kind of microfabricated microrobot based on the use of bistable modules is designed to perform open-loop controlled micropositioning tasks. The DiMiBot (Digital MicroroBot) opens a new paradigm in the design of microrobots by using mechanical stability instead of complex control strategies. We propose a new architecture of digital microrobot for which forward and inverse kinematics models are easy to use. These kinematic models are validated with FEA simulations before the fabrication of a real DiMiBot prototype. Tests and characterization of the prototype are made and compared to the desired behavior. Thanks to its submicrometric resolution and to its small dimensions ( 400 μm thickness), it is able to manipulate micro-objects in confined environments, where no other robot can be used

Toward the use of proxies for efficient learning manipulation and locomotion strategies on soft robots

Soft robots are naturally designed to perform safe interactions with their environment, like locomotion and manipulation. In the literature, there are now many concepts, often bio-inspired, to propose new modes of locomotion or grasping. However, a methodology for implementing motion planning of these tasks, as exists for rigid robots, is still lacking. One of the difficulties comes from the modeling of these robots, which is very different, as it is based on the mechanics of deformable bodies. These models, whose dimension is often very large, make learning and optimization methods very costly. In this paper, we propose a proxy approach, as exists for humanoid robotics. This proxy is a simplified model of the robot that enables frugal learning of a motion strategy. This strategy is then transferred to the complete model to obtain the corresponding actuation inputs. Our methodology is illustrated and analyzed on two classical designs of soft robots doing manipulation and locomotion tasks.Comment: Accepted at IEEE Robotics and Automation Letters (RAL) in October 202

Stability of Cooperating Manipulators with Hybrid Position/Force Control and Time Delay

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Cooperative control of a vibrating flexible object by a rigid dual-arm robot

科研費報告書収録論文(課題番号:07455416・基盤研究(B)(2)・H7～H9/研究代表者:内山, 勝/フレキシブル双腕ロボットの協調制御に関する研究

Model Based Control of Soft Robots: A Survey of the State of the Art and Open Challenges

Continuum soft robots are mechanical systems entirely made of continuously deformable elements. This design solution aims to bring robots closer to invertebrate animals and soft appendices of vertebrate animals (e.g., an elephant's trunk, a monkey's tail). This work aims to introduce the control theorist perspective to this novel development in robotics. We aim to remove the barriers to entry into this field by presenting existing results and future challenges using a unified language and within a coherent framework. Indeed, the main difficulty in entering this field is the wide variability of terminology and scientific backgrounds, making it quite hard to acquire a comprehensive view on the topic. Another limiting factor is that it is not obvious where to draw a clear line between the limitations imposed by the technology not being mature yet and the challenges intrinsic to this class of robots. In this work, we argue that the intrinsic effects are the continuum or multi-body dynamics, the presence of a non-negligible elastic potential field, and the variability in sensing and actuation strategies.Comment: 69 pages, 13 figure

Inverse real-time Finite Element simulation for robotic control of flexible needle insertion in deformable tissues

International audienceThis paper introduces a new method for automatic robotic needle steering in deformable tissues. The main contribution relies on the use of an inverse Finite Element (FE) simulation to control an articulated robot interacting with deformable structures. In this work we consider a flexible needle, embedded in the end effector of a 6 arm Mitsubishi RV1A robot, and its insertion into a silicone phantom. Given a trajectory on the rest configuration of the silicone phantom, our method provides in real-time the displacements of the articulated robot which guarantee the permanence of the needle within the predefined path, taking into account any undergoing deformation on both the needle and the trajectory itself. A forward simulation combines i) a kinematic model of the robot, ii) FE models of the needle and phantom gel iii) an interaction model allowing the simulation of friction and puncture force. A Newton-type method is then used to provide the displacement of the robot to minimize the distance between the needle's tip and the desired trajectory. We validate our approach with a simulation in which a virtual robot can successfully perform the insertion while both the needle and the trajectory undergo significant deformations

The coordinated control of space robot teams for the on-orbit construction of large flexible space structures

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references (leaves 95-103).Teams of autonomous space robots are needed for future space missions such as the construction of large solar power stations and large space telescopes in earth orbit. This work focuses on the control of teams of robots performing construction tasks such as manipulation and assembly of large space structures. The control of the robot structure system is difficult. The space structures are flexible and there are significant dynamic interactions between the robots and the structures. Forces applied by the robots may excite undesirable vibrations in the structures. Furthermore, the changing configuration of the system results in the system dynamics being described by a set of non-linear partial differential equations. Limited sensing and actuation in space present additional challenges. The approach proposed here is to transform the system dynamics into a set of linear time-varying ordinary differential equations. The control of the high-frequency robots can be decoupled from the control of the low-frequency structures. This approach allows the robots to apply forces to the structures and control the dynamic interactions between the structures and the robots. The approach permits linear optimal control theory to be used. Simulation studies and experimental verification demonstrate the validity of the approach.by Peggy Boning.Ph.D