TechTalks from event: Technical session talks from ICRA 2012

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Biologically Inspired Robotics

  • Estimation of Relative Position and Coordination of Mobile Underwater Robotic Platforms through Electric Sensing Authors: Morel, Yannick; Porez, Mathieu; Ijspeert, Auke
    In the context of underwater robotics, positioning and coordination of mobile agents can prove a challenging problem. To address this issue, we propose the use of electric sensing, with a technique inspired by weakly electric fishes. In particular, the approach relies on one or several of the agents applying an electric field to their environment. Using electric measures, others agents are able to reconstruct their relative position with respect to the emitter, over a range that is function of the geometry of the emitting agent and of the power applied to the environment. Efficacy of the technique is illustrated using a number of numerical examples. The approach is shown to allow coordination of unmanned underwater vehicles, including that of bio-inspired swimming robotic platforms.
  • Localization of Small Objects with Electric Sense Based on Kalman Filter Authors: Lebastard, Vincent; Chevallereau, Christine; GIRIN, Alexis; Boyer, Frédéric; Gossiaux, Pol Bernard
    Electric fish feel the perturbations of a selfgenerated electric field through their electro-receptive skin. This sense allows them to navigate and reconstruct their environment in conditions where vision and sonar cannot work. In this article, we use a sensor bio-inspired from this active sense to address the problem of small objects reconstruction and electrolocation. Based on a Kalman filter, any small object in the surrounding of the motion controlled sensor can be encapsulated into an equivalent sphere whose location is well estimated by the filter. Experimental results illustrate the feasibility of the approach.
  • Non-Visual Orientation and Communication by Fishes Using Electrical Fields: A Model System for Underwater Robotics Authors: von der Emde, Gerhard; Gebhardt, Kristina; Behr, Katharina
    Building autonomous underwater robots is a challenging problem. Different sensory modalities have been employed successfully, some inspired by human and animal senses. The European ANGELS project uses an electric sense inspired by weakly electric fish. These fish have the unique ability to navigate and orient in complete darkness by using self-produced electrical fields. They emit electric signals into the environment, which in turn they perceive with an array of electroreceptor organs in their skin. The fish's whole body serves as an antenna, which shapes the emitted electrical field. As a result, the animals are able to detect, localize and analyze objects in their vicinity and to perceive a 3-dimensional electrical picture of their surroundings. Here, we review biological experimental results highlighting the animal's perceptual abilities, which allow them to navigate in extreme environments where vision can not be used. In addition, electric fishes use electric signals for communication. Behavioral communication strategies such as synchronization of electric signals and fixed-order-signaling can play a role in group coherence. Because of their unique sensory abilities, electric fish can serve as a model system for roboticists building underwater vehicles that can communicate and navigate in extreme environments where vision is not possible. In ANGELS, the electric sense is used to navigate a robot without knowledge of the surroundings, keep multi robots in formation, reco
  • An Underwater Reconfigurable Robot with Bioinspired Electric Sense Authors: Mintchev, Stefano; Stefanini, Cesare; GIRIN, Alexis; Marrazza, Stefano; Orofino, Stefano; Lebastard, Vincent; Manfredi, Luigi; Dario, Paolo; Boyer, Frédéric
    Morphology, perception and locomotion are three key features highly inter-dependent in robotics. This paper gives an overview of an underwater modular robotic platform equipped with a bio-inspired electric sense. The platform is reconfigurable in the sense that it can split into independent rigid modules and vice-versa. Composed of 9 modules, the longer entity can swim like an eel over long distances, while once detached, each of its modules is efficient for small displacements with a high accuracy. Challenges are to mechanically ensure the morphology changes and to do it automatically. Electric sense is used to guide the modules during docking phases and to navigate in unknown scenes. Several aspects of the design of the robot are described and a particular attention is paid to the inter-module docking system. The feasibility of the design is assessed through experiments.
  • Underwater Electro-Navigation in the Dark Authors: Lebastard, Vincent; Boyer, Frédéric; Chevallereau, Christine; Servagent, Noël
    This article proposes a solution to the problem of the navigation of underwater robots in confined unstructured environments wetted by turbid waters. The solution is based on a new sensor bio-inspired from electric fish. Exploiting the morphology of the sensor as well as taking inspiration from passive electro-location in real fish, the solution turns out to be a sensory-motor loop encoding a simple behavior relevant to exploration missions. This behavior consists in seeking conductive objects while avoiding insulating ones. The solution is illustrated on experiments. It is robust and works even in very unstructured scenes. It does not require any model and is quite cheap to implement
  • Electric Sensor Based Control for Underwater Multi-Agents Navigation in Formation Authors: Chevallereau, Christine; Boyer, Frédéric; Lebastard, Vincent; benachenhou, mohamed
    Thanks to an electro-sensible skin, some species of fish can feel the perturbations of a self generated electric field caused by their surroundings variations. Known under the name of "electric-sense", this ability allows these fish to communicate and navigate in confined surroundings wetted by turbid waters where vision and sonar cannot work. Based on a bio-inspired electric sensor recently proposed in [1], this article presents a first attempt to use electric sense for the navigation in formation of a set of rigid underwater vehicles. The navigation strategy combines some behaviors observed in electric fish as well as a follower-leader strategy well known from multi-robot navigation. Being based one the servoing of the electric measurements, these laws do not require the knowledge of the location of the agents as this is usually the case in multi-robot navigation. At the end of the analysis, sufficient convergence conditions of the resulting control laws are given. Moreover, some limits on the possible motion of the leader are exhibited and the importance of the choice of controlled outputs is discussed too. Finally, simulation results illustrate the feasibility of the approach.

Novel Robot Designs

  • Optimal Design of Nonlinear Profile of Gear Ratio Using Non-Circular Gear for Jumping Robot Authors: Okada, Masafumi; Takeda, Yushi
    In this paper, we develop a design method of nonlinear profile of gear ratio to utilize a DC servo motor effectively for jumping robot. Because the larger ground force yields the higher kinetic energy of the robot body, the optimal gear ratio is obtained by the maximization of the ground force from statics point of view. Moreover, the varying gear ratio during the jump motion is obtained through a simulation which connects statics-based optimization and robot dynamics. A non-circular gear is synthesized which realizes the obtained optimal varying gear ratio. The effectiveness of the proposed method is evaluated by simulations.
  • Stackable Manipulator for Mobile Manipulation Robot Authors: Lee, Hoyul; Oh, Yonghwan; Choi, Youngjin
    This paper proposes a new manipulator concept applied to a mobile robot manipulation system for reducing robot size and weight or increasing its work capacities such as a ayload, operating radius, and operating speed. In detail, we propose a new robotic manipulator that uses stackable 4- BAR mechanisms for mobile manipulation robot. The proposed mechanism provides a clear advantage in which all the ctuators can be separated from the working joints. Thus, the mechanism is able to select the Center of Mass (CoM) and the Zero-Moment Point (ZMP) in arbitrary points without any support from ZMP controller or ZMP compensation method. To confirm efficiency of the new manipulator, this paper ddresses a design method using the simplified beam theory, based on the well-known Finite Element Method (FEM) for structural stiffness analysis of linkages. The reason behind this is that the CoM and ZMP are dependent on the weight of the motors and the linkages. Ultimately, we show the efficiency of the proposed stackable manipulator through simulations and experiments.
  • Development of Hair-Washing Robot Equipped with Scrubbing Fingers Authors: Hirose, Toshinori; Fujioka, Soichiro; Mizuno, Osamu; Nakamura, Tohru
    We have developed the world's first hair-washing robot equipped with scrubbing fingers. This robot assists in washing hair in hospitals or care facilities, and it eases the burden of healthcare professionals and care workers while it brings a higher quality of life to patients and others in need of nursing care. It features the mechanical and control technologies needed for touching someone gently on the head. These include, for instance, the self-aligning mechanism and the cylindrical rack mechanism of the robot's end effector, the parallel link mechanism of its pressing arm, and the compliance control for providing an appropriate sense of pressure.
  • I-Hand: An Intelligent Robotic Hand for Fast and Accurate Assembly in Electronic Manufacturing Authors: CHEN, FEI; Sekiyama, Kosuke; Di, Pei; Huang, Jian; Fukuda, Toshio
    In electronics manufacturing system, the design of the robotic gripper is important for the successful accomplishment of the assembly task. Due to the restriction of the architecture of traditional robotic grippers, the status of assembly parts during the assembly process cannot be effectively detected. In this research, an intelligent robotic gripper – i-Hand equipped with multiple small sensors is designed and built for this purpose, getting the essential parameters for some specific mathematical model. Mating connectors by robot, as a experimental case in this paper, is studied to evaluate the performance of i-Hand. A simple new model is proposed to describe the process of mating connectors, within which the distance between the connector and deformable Printed Circuit Board (PCB) is detected by i-Hand. An online Fault Detection and Diagnosis algorithm (FDD) is proposed. Various possible situations during assembly are detected and handled by using sensor data fusion. The effectiveness of proposed model and algorithm is proved by the experiments.
  • A Radial Crank-Type Continuously Variable Transmission Driven by Two Ball Screws Authors: Yamada, Hiroya
    Power-to-weight ratio of actuators is extremely important for robots, particularly mobile robots. The combination of electric motor and speed reducer, which is the most common driving mechanism for robots, can utilize the motor in the area where its power output is high when the reduction ratio is appropriately designed relative to the load. However, in the case of applications in which the load significantly changes, the motor has to be operated in the area where its power output significantly drops. This problem has restricted the capability of mobile robots, especially biologically inspired robots. Therefore in this paper I focus on a continuously variable transmission (CVT). Crank-type CVTs, which have been used for robotic joints, have the major disadvantage of a limited range of motion due to the dead point of the crank. Thus, this paper proposes the Radial Crank-type CVT (RC-CVT), which overcomes this limit of range of motion by increasing the number of links driving the crank of the CVT. This RC-CVT holds promise as an efficient robotic joint as it can utilize ball screws. This paper shows the equations of kinematics and statics of the RC-CVT and also describes the design and test of the prototype. The application to a quadruped robot is also introduced.
  • Rolling Tensegrity Driven by Pneumatic Soft Actuators Authors: Koizumi, Yuusuke; Shibata, Mizuho; Hirai, Shinichi
    In this paper, we describe the rolling of a tensegrity robot driven by a set of pneumatic soft actuators. Tensegrity is a mechanical structure consisting of a set of rigid elements connected by elastic tensional elements. Introducing tensegrity structures, we are able to build soft robots with larger size. Firstly, we show the prototype of a six-strut tensegrity robot, which is driven by twenty-four pneumatic McKibben actuators. Second, we formulate the geometry of the tensegrity robot. We categorize contact states between a six-strut tensegrity robot and a flat ground into two; axial symmetric contact and planar symmetric contact. Finally, we experimentally examine if rolling can be performed over a flat ground for individual sets of the actuators and discuss the strategy of rolling.

Underactuated Grasping

  • Selectively Compliant Underactuated Hand for Mobile Manipulation Authors: Aukes, Daniel; Cutkosky, Mark; Garcia, Pablo; Kim, Susan; Edsinger, Aaron
    The demands of mobile manipulation are leading to a new class of multi-fingered hands with a premium on being lightweight and robust as well as being able to grasp and perform basic manipulations with a wide range of objects. A promising approach to addressing these goals is to use compliant, underactuated hands with selectively lockable degrees of freedom. This paper presents the design of one such hand that combines series-elastic actuation and electrostatic braking at the joints. A numerical analysis shows how the maximum pullout force varies as a function of kinematic parameters, spring forces at the joints and brake torques.
  • Precision Grasping and Manipulation of Small Objects from Flat Surfaces Using Underactuated Fingers Authors: Odhner, Lael; Ma, Raymond; Dollar, Aaron
    In this paper we demonstrate an underactuated finger design and grasping method for precision grasping and manipulation of relatively small objects. Taking a cue from human manipulation, we introduce the flip-and-pinch task, in which the hand picks up thin objects from a table surface by flipping it into a stable configuration. Despite the fact that finger motions are not fully constrained by the hand actuators, we demonstrate that the hand and fingers can be configured with the table surface to produce a set of constraints that result in a repeatable quasi-static motion trajectory. This approach is shown to be robust for a variety of object sizes, even when utilizing identical open-loop kinematic playback. Experimental results suggest that the advantages of underactuated, adaptive robot hands can be carried over to dexterous, precision tasks as well.
  • Grasp and Manipulation Analysis for Synergistic Underactuated Hands under General Loading Conditions Authors: Gabiccini, Marco; Farnioli, Edoardo; Bicchi, Antonio
    In dexterous grasping, the development of simple but practical hands with reduced number of actuators, designed to perform some manipulation tasks, is both attractive and challenging. To carefully synthesize inter- and intra-finger couplings a rigorous way to establish grasping and manipulation properties of an underactuated hand is of paramount importance. In this paper, we propose a general approach to characterize the structural properties of underactuated hands focusing on their kinematic and force analysis. A complete kinostatic characterization of a given grasp (pure squeeze, spurious squeeze, kinematic grasp displacements and so on) is introduced. The analysis is quasi-static but it is not limited to rigid-body motions, encompassing also essential elastic motions, statically indeterminate configurations, and pre-loaded initial conditions. The introduction of generalized compliance at contacts and in the actuation mechanism is included, as it is an essential feature of safe and dependable modern hands. Efficient algorithms to characterize the system behavior are presented and applied in two different numerical examples.
  • Towards a Design Optimization Method for Reducing the Mechanical Complexity of Underactuated Robotic Hands Authors: Hammond III, Frank L.; Weisz, Jonathan; de la Llera Kurth, Andres; Allen, Peter; Howe, Robert D.
    Underactuated compliant robotic hands exploit passive mechanics and joint coupling to reduce the number of actuators required to achieve grasp robustness in unstructured environments. Reduced actuation requirements generally serve to decrease design cost and improve grasp planning efficiency, but overzealous simplification of an actuation topology, coupled with insufficient tuning of mechanical compliance and hand kinematics, can adversely affect grasp quality and adaptability. This paper presents a computational framework for reducing the mechanical complexity of robotic hand actuation topologies without significantly decreasing grasp robustness. Open-source grasp planning software and well-established grasp quality metrics are used to simulate a fully-actuated, 24 DOF anthropomorphic robotic hand grasping a set of daily living objects. DOFs are systematically demoted or removed from the hand actuation topology according to their contribution to grasp quality. The resulting actuation topology contained 22% fewer DOFs, 51% less aggregate joint motion, and required 82% less grasp planning time than the fully-actuated design, but decreased average grasp quality by only 11%.
  • Seashell Effect Pretouch Sensing for Robotic Grasping Authors: Jiang, Liang-Ting; Smith, Joshua R.
    This paper introduces "seashell effect pretouch sensing", and demonstrates application of this new sensing modality to robot grasp control, and also to robot grasp planning. "Pretouch" refers to sensing modalities that are intermediate in range between tactile sensing and vision. The novel pretouch technique presented in this paper is effective on materials that prior pretouch techniques fail on. Seashell effect pretouch is inspired by the phenomenon of "hearing the sea" when a seashell is held to the ear, a phenomenon which depends on shell position. To turn this effect into a sensor, a cavity and microphone were built into a robot finger. The sensor detects changes in the spectrum of ambient noise that occur when the finger approaches an object. Environmental noise is amplified most at the cavity's resonant frequency, which changes as the cavity approaches an object. After introducing the sensing modality and characterizing its performance, the paper describes experiments performed with prototype sensors integrated into the Willow Garage PR2's gripper. We explore two primary applications: (1) reactive grasp control and (2) pretouch-assisted grasp planning.
  • Position Control of Tendon-Driven Fingers with Position Controlled Actuators Authors: Abdallah, Muhammad; Platt, Robert; Hargrave, Brian; Permenter, Frank
    Conventionally, tendon-driven manipulators implement some force-based controller using either tension feedback or dynamic models of the actuator. The force control allows the system to maintain proper tensions on the tendons. In some cases, whether it is due to the lack of tension feedback or actuator torque control, a purely position-based controller is needed. This work compares three position controllers for tendon-driven manipulators that implement a nested actuator position controller. A new controller is introduced that achieves the best overall performance with regards to speed, accuracy, and transient behavior. To compensate for the lack of tension control, the controller nominally maintains the internal tension on the tendons through a range-space constraint on the actuator positions. These control laws are validated experimentally on the Robonaut-2 humanoid hand.