Sensitive Manipulation

PhD thesisThis thesis presents an effective alternative to the traditionalapproach to robotic manipulation. In our approach, manipulation ismainly guided by tactile feedback as opposed to vision. Themotivation comes from the fact that manipulating an object impliescoming in contact with it, consequently, directly sensing physicalcontact seems more important than vision to control theinteraction of the object and the robot. In this work, thetraditional approach of a highly precise arm and vision systemcontrolled by a model-based architecture is replaced by one thatuses a low mechanical impedance arm with dense tactile sensing andexploration capabilities run by a behavior-based architecture.The robot OBRERO has been built to implement this approach. Newtactile sensing technology has been developed and mounted on therobot's hand. These sensors are biologically inspired and presentmore adequate features for manipulation than those of state of theart tactile sensors. The robot's limb was built with compliantactuators, which present low mechanical impedance, to make theinteraction between the robot and the environment safer than thatof a traditional high-stiffness arm. A new actuator was created tofit in the hand size constraints. The reduced precision ofOBRERO's limb is compensated by the capability of explorationgiven by the tactile sensors, actuators and the softwarearchitecture.The success of this approach is shown by picking up objects in anunmodelled environment. This task, simple for humans, has been achallenge for robots. The robot can deal with new, unmodelledobjects. OBRERO can come gently in contact, explore, lift, andplace the object in a different location. It can also detectslippage and external forces acting on an object while it is held.Each one of these steps are done by using tactile feedback. Thistask can be done with very light objects with no fixtures and onslippery surfaces

Sensitive manipulation

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 161-172).This thesis presents an effective alternative to the traditional approach to robotic manipulation. In our approach, manipulation is mainly guided by tactile feedback as opposed to vision. The motivation comes from the fact that manipulating an object implies coming in contact with it, consequently, directly sensing physical contact seems more important than vision to control the interaction of the object and the robot. In this work, the traditional approach of a highly precise arm and vision system controlled by a model-based architecture is replaced by one that uses a low mechanical impedance arm with dense tactile sensing and exploration capabilities run by a behavior-based architecture. The robot OBRERO has been built to implement this approach. New tactile sensing technology has been developed and mounted on the robot's hand. These sensors are biologically inspired and present more adequate features for manipulation than those of state of the art tactile sensors. The robot's limb was built with compliant actuators, which present low mechanical impedance, to make the interaction between the robot and the environment safer than that of a traditional high-stiffness arm. A new actuator was created to fit in the hand size constraints.(cont.) The reduced precision of OBRERO's limb is compensated by the capability of exploration given by the tactile sensors, actuators and the software architecture. The success of this approach is shown by picking up objects in an unmodelled environment. This task, simple for humans, has been a challenge for robots. The robot can deal with new, unmodelled objects. OBRERO can come gently in contact, explore, lift, and place the object in a different location. It can also detect slippage and external forces acting on an object while it is held. Each one of these steps are done by using tactile feedback. This task can be done with very light objects with no fixtures and on slippery surfaces.by Eduardo Rafael Torres Jara.Ph.D

Neues Konzept zur Planung, Ausführung und Überwachung von Roboteraufgaben mit hierarchischen Petri-Netzen

Es wird gezeigt, wie die aufgabenausführungsrelevanten Komponenten einer hybriden Steuerungsarchitektur mit Hilfe von hierarchischen Petri-Netzen umgesetzt, integriert und mit Überwachungsmodulen verknüpft werden können. Hierzu wird zunächst ein Konzept zur Generierung von Aufgabenwissen vorgeschlagen, das es erlaubt Bausteine komplexer Handlungen systematisiert zu entwerfen. Im Anschluss wird ein neues Konzept zur online Überwachung von Bewegungsvorgängen bei humanoiden Robotern vorgestellt

Compliant control of Uni/ Multi- robotic arms with dynamical systems

Accomplishment of many interactive tasks hinges on the compliance of humans. Humans demonstrate an impressive capability of complying their behavior and more particularly their motions with the environment in everyday life. In humans, compliance emerges from different facets. For example, many daily activities involve reaching for grabbing tasks, where compliance appears in a form of coordination. Humans comply their handsâ motions with each other and with that of the object not only to establish a stable contact and to control the impact force but also to overcome sensorimotor imprecisions. Even though compliance has been studied from different aspects in humans, it is primarily related to impedance control in robotics. In this thesis, we leverage the properties of autonomous dynamical systems (DS) for immediate re-planning and introduce active complaint motion generators for controlling robots in three different scenarios, where compliance does not necessarily mean impedance and hence it is not directly related to control in the force/velocity domain. In the first part of the thesis, we propose an active compliant strategy for catching objects in flight, which is less sensitive to the timely control of the interception. The soft catching strategy consists in having the robot following the object for a short period of time. This leaves more time for the fingers to close on the object at the interception and offers more robustness than a âhardâ catching method in which the hand waits for the object at the chosen interception point. We show theoretically that the resulting DS will intercept the object at the intercept point, at the right time with the desired velocity direction. Stability and convergence of the approach are assessed through Lyapunov stability theory. In the second part, we propose a unified compliant control architecture for coordinately reaching for grabbing a moving object by a multi-arm robotic system. Due to the complexity of the task and of the system, each arm complies not only with the objectâs motion but also with the motion of other arms, in both task and joint spaces. At the task-space level, we propose a unified dynamical system that endows the multi-arm system with both synchronous and asynchronous behaviors and with the capability of smoothly transitioning between the two modes. At the joint space level, the compliance between the arms is achieved by introducing a centralized inverse kinematics (IK) solver under self-collision avoidance constraints; formulated as a quadratic programming problem (QP) and solved in real-time. In the last part, we propose a compliant dynamical system for stably transitioning from free motions to contacts. In this part, by modulating the robot's velocity in three regions, we show theoretically and empirically that the robot can (I) stably touch the contact surface (II) at a desired location, and (III) leave the surface or stop on the surface at a desired point

相対座標における高速視覚フィードバックに基づくダイナミックコンペンセーション

学位の種別:課程博士University of Tokyo(東京大学