TechTalks from event: Technical session talks from ICRA 2012

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Hand Modeling and Control

  • Reduced Dimensionality Control for the ACT Hand Authors: Malhotra, Mark; Rombokas, Eric; Theodorou, Evangelos; Todorov, Emanuel; Matsuoka, Yoky
    Redundant tendon-driven systems such as the human hand or the ACT robotic hand are high-dimensional and nonlinear systems that make traditional control strategies ineffective. The synergy hypothesis from neuroscience suggests that employing dimensionality reduction techniques can simplify the system without a major loss in function. We define a dimensionality reduction framework consisting of separate observation and activation synergies, a first-order model, and an optimal controller. The framework is implemented for two example tasks: adaptive control of thumb posture and hybrid position/force control to enable dynamic handwriting.
  • A Functional Anatomy Based Kinematic Human Hand Model with Simple Size Adaptation Authors: van der Hulst, Frank; Schätzle, Simon; Schiele, Andre; Preusche, Carsten
    For the purpose of ergonomic human-machine interaction and geometrical design of hand held haptic devices, a kinematic model that represents the functional anatomy of different human hands is desired. It is the goal of this paper to present a kinematic hand model that is based on human physiology and that is easily adaptable to represent various real human hand sizes. This is achieved by exploiting body proportions to derive finger segment lengths from the hand length. A partial hand model validation, involving index- and middle finger validation using a group of subjects, indicates that the use of body proportions offers a good estimate of finger length from a given hand length. Model estimated fingertip positions over a motion trajectory remain within reasonable limits when compared with experimental data for this subject group. The model is promising for usage in practical situations since only hand length, which is easy to measure or to obtain from literature, is required as an input. Phalange lengths, which are sparsely available from literature and difficult to measure, are generated by the model.
  • Balancing Anatomy and Function in a Musculoskeletal Model of Hands Authors: Blasdel, Aaron Michael; Ikegami, Yosuke; Ayusawa, Ko; Nakamura, Yoshihiko
    Musculoskeletal models are effective tools for understanding living systems. To ensure proper model function, they must be checked against the literature or specimens. Existing checking methods require cadaver experimentation, highly knowledgeable medical personnel, and/or significant time. In this paper, we propose a quick and efficient method, called functional consistency checking, for use when these resources are not available. This method uses the literature to define a set of mathematical constraints, custom inverse dynamics software to interact with the model and its Jacobian in realtime and then evaluates the models consistency with these constraints. The method's usefulness will be demonstrated by constructing a human hand prototype, performing functional consistency checking, and then comparing the original to the output using data from a pianist motion capture.
  • Grasping by Caging: A Promising Tool to Deal with Uncertainty Authors: Wan, Weiwei; Fukui, Rui; Shimosaka, Masamichi; Sato, Tomomasa
    This paper presents a novel approach to deal with uncertainty in grasping. The basic idea is to initiate a caging manipulation state and then shrink fingers into immobilization to perform a practical grasping. Thanks to flexibility from caging, this procedure is intrinsically safe and gains tolerance towards uncertainty. Besides, we demonstrate that the minimum caging is immobilization and consequently propose using three or four fingers to manipulate planar convex objects in a grasping-by-caging way. Experimental results with physical simulation show the robustness and efficacy of our approach. We expect its leading benefits in saving finger number, conquering low-friction materials and especially, dealing with pose/shape uncertainty.
  • Caging-Based Grasping by a Robot Hand with Rigid and Soft Parts Authors: Maeda, Yusuke; Kodera, Naoki; Egawa, Tomohiro
    Caging is a method to make an object inescapable from a closed region by rigid bodies. Position-controlled robot hands can capture an object and manipulate it via caging without force sensing or force control. However, the object in caging is freely movable in the closed region, which may not be allowed in some applications. In such cases, grasping is required. In this paper, we propose a new simple approach to grasping by position-controlled robot hands with the advantage of caging: caging-based grasping by a robot hand with rigid and soft parts. In caging-based grasping, we cage an object with the rigid parts of the hand, and construct a complete grasp with the soft parts. We formulate the caging-based grasping, and derive concrete conditions for caging-based grasping in planar and spatial cases, and show some experimental results.

Multi-Robot Systems 1

  • Fully Distributed Scalable Smoothing and Mapping with Robust Multi-Robot Data Association Authors: Cunningham, Alexander; Wurm, Kai M.; Burgard, Wolfram; Dellaert, Frank
    In this paper we focus on the multi-robot perception problem, and present an experimentally validated end-to-end multi-robot mapping framework, enabling individual robots in a team to see beyond their individual sensor horizons. The inference part of our system is the DDF-SAM algorithm, which provides a decentralized communication and inference scheme, but did not address the crucial issue of data association. One key contribution is a novel, RANSAC-based, approach for performing the between-robot data associations and initialization of relative frames of reference. We demonstrate this system with both data collected from real robot experiments, as well as in a large scale simulated experiment demonstrating the scalability of the proposed approach.
  • Collaborative 3D Localization of Robots from Relative Pose Measurements Using Gradient Descent on Manifolds Authors: Knuth, Joseph; Barooah, Prabir
    We propose a distributed algorithm for estimating the full 3-D pose (position and orientation) of multiple autonomous vehicles with respect to a common reference frame when GPS is not available. This algorithm does not rely on the use of any maps, or the ability to recognize landmarks in the environment. Instead we assume that noisy measurements of the relative pose between pairs of robots are intermittently available. We utilize the additional information about each robot's pose provided by these measurements to improve over self-localization estimates. The proposed method is based on solving an optimization problem in an underlying product manifold (SO(3)x R<sup>3</sup>)<sup>n(k)</sup>. A provably correct explicit gradient descent law is provided. Unlike many previous approaches, the proposed algorithm is applicable to the 3-D case. The method is also capable of handling a fully dynamic scenario where the neighbor relationships are time-varying. Simulations show that the errors in the localization estimates obtained using this algorithm are significantly lower then what is achieved when robots estimate their pose without cooperation. Results from experiments with a pair of ground robots with vision-based sensors reinforce these findings.
  • Distributed Source Seeking by Cooperative Robots: All-To-All and Limited Communications Authors: Li, Shuai; Guo, Yi
    We consider the problem of source seeking using a group of mobile robots equipped with sensors for concentration measurement (instead of the gradient). In our formulation, each robot maintains a gradient estimation, moves to the source by tracing the gradient, and all together keep a predefined formation in movement. We present two control algorithms with all-to-all and limited communications, respectively. The estimation error is taken into account to derive robust control algorithms. Comparing to existing methods, the proposed algorithm with limited communications is fully distributed, that is, each robot needs only to communicate with its one-hop neighbors and no across-hop message passing is required. Both theoretical analysis and numerical simulations are given to validate the effectiveness of our methods.
  • A Coordination Strategy for Multi-Robot Sampling of Dynamic &#64257; Elds Authors: Antonelli, Gianluca; Marino, Alessandro; Chiaverini, Stefano
    A coordination mechanism to achieve the sampling task of static or dynamic fields by means of a system composed by multiple mobile robots is addressed in this paper. The problem is the estimation of a scalar field. To this aim in a probabilistic framework a solution is proposed that takes into account several constraints. The attention is focused on the vehicles motion generation and the developed strategy is designed for multiple, autonomous and distributed robots. It makes use of the Voronoi tessellation's properties to automatically distribute the vehicles' motion and of the Null-Space-Behavioral control to handle eventually conflicting motion tasks (as reaching a given point while avoiding obstacles). The algorithm can be tailored based on the communication and computational capabilities of the robots. A discussion and possible counterexamples of the applications of existing approaches are provided in the paper. Numerical simulations illustrate the results.
  • On Localization Uncertainty in an Autonomous Inspection Authors: Faigl, Jan; Krajnik, Tomas; Vonasek, Vojtech
    This paper presents a multi-goal path planning framework based on a self-organizing map algorithm and a model of the navigation describing evolution of the localization error. The framework combines finding a sequence of goals' visits with a goal-to-goal path planning considering localization uncertainty. The approach is able to deal with local properties of the environment such as expected visible landmarks usable for the navigation. The local properties affect the performance of the navigation, and therefore, the framework can take the full advantage of the local information together with the global sequence of the goals' visits to find a path improving the autonomous navigation. Experimental results in real outdoor and indoor environments indicate that the framework provides paths that effectively decreases the localization uncertainty; thus, increases the reliability of the autonomous goals' visits.
  • Probabilistic Spatial Mapping and Curve Tracking in Distributed Multi-Agent Systems Authors: Williams, Ryan; Sukhatme, Gaurav
    In this paper we consider a probabilistic method for mapping a spatial process over a distributed multi-agent system and a coordinated level curve tracking algorithm for adaptive sampling. As opposed to assuming the independence of spatial features (e.g. an occupancy grid model), we adopt a novel model of spatial dependence based on the grid-structured Markov random field that exploits spatial structure to enhance mapping. The multi-agent Markov random field framework is utilized to distribute the model over the system and to decompose the problem of global inference into local belief propagation problems coupled with neighbor-wise inter-agent message passing. A Lyapunov stable control law for tracking level curves in the plane is derived and a method of gradient and Hessian estimation is presented for applying the control in a probabilistic map of the process. Simulation results over a real-world dataset with the goal of mapping a plume-like oceanographic process demonstrate the efficacy of the proposed algorithms. Scalability and complexity results suggest the feasibility of the approach in realistic multi-agent deployments.

Medical Robotics I

  • Metal MEMS Tools for Beating-Heart Tissue Removal Authors: Gosline, Andrew; Vasilyev, Nikolay; Veeramani, Arun; Wu, MingTing; Schmitz, Greg; Chen, Rich; Arabagi, Veaceslav; del Nido, Pedro; Dupont, Pierre
    A novel robotic tool is proposed to enable the surgical removal of tissue from inside the beating heart. The tool is manufactured using a unique metal MEMS process that provides the means to fabricate fully assembled devices that incorporate micron-scale features in a millimeter scale tool. The tool is integrated with a steerable curved concentric tube robot that can enter the heart through the vasculature. Incorporating both irrigation and aspiration, the tissue removal system is capable of extracting substantial amounts of tissue under teleoperated control by first morselizing it and then transporting the debris out of the heart through the lumen of the robot. Tool design and robotic integration are described and ex vivo experimental results are presented.
  • Motion Planning for Multiple Millimeter-Scale Magnetic Capsules in a Fluid Environment Authors: Vartholomeos, Panagiotis; Akhavan-Sharif, Reza; Dupont, Pierre
    There are many examples of minimally invasive surgery in which tethered robots are incapable of accurately reaching target locations deep inside the body either because they are too large and so cause tissue damage or because the tortuosity of the path leads to loss of tip control. In these situations, small untethered magnetically-powered robots may hold the potential to act as delivery vehicles for therapeutic agents. While MRI scanners provide a means to power, control and image such robots as they move throughout the body, a substantial challenge arises if the clinical application requires more than one such robot. The resulting system is underactuated and thus its controllability is in question. This paper presents a simple motion planning algorithm for two magnetic capsules and demonstrates through simulation and experiment that nonlinear fluid damping can be exploited to independently control the positions of the capsules.
  • Geometry Effect of Preloading Probe on Accurate Needle Insertion for Breast Tumor Treatment Authors: HATANO, Maya; Kobayashi, Yo; SUZUKI, Makiko; Fujie, Masakatsu G.
    We herein describe a needle insertion method involving tissue preloading for accurate breast tumor treatment. A mechanical preloading probe locates a tumor lesion from ultrasound imaging information and reduces lesion displacement during needle insertion by pressing the breast tissue. We validated the insertion accuracy of this method by numerical simulation and experiments both in vitro and in vivo. For further accuracy enhancement, we evaluated the geometry effect of the preloading probe on needle insertion accuracy by experiments in vitro. We compared the insertion accuracy between insertion with preloading using different probe diameters and normal needle insertion. In addition, we compared insertion accuracy at different tumor depths. The data indicated a tendency for adaptation of larger preloading probe diameters with deeper tumors. This suggests the potential for our method to enhance placement accuracy by real-time geometry regulation.
  • A MRI-Guided Concentric Tube Continuum Robot with Piezoelectric Actuation: A Feasibility Study Authors: Su, Hao; Cardona, Diana; Shang, Weijian; Cole, Gregory; Rucker, Caleb; Webster III, Robert James; Fischer, Gregory Scott
    This paper presents a versatile magnetic resonance imaging (MRI) compatible concentric tube continuum robotic system. The system enables MR image-guided placement of a curved, steerable active cannula. It is suitable for a variety of clinical applications including image-guided neurosurgery and percutaneous interventions, along with procedures that involve accessing a desired image target, through a curved trajectory. The robotic device is piezoelectrically actuated to provide precision motion with joint-level precision of better than 0.03mm, and is fully MRI-compatible allowing simultaneous cannula motion and imaging with no image quality degradation. The MRI compatibility of the robot has been evaluated under 3 Tesla MRI using standard prostate imaging sequences, with an average signal to noise ratio loss of less than 2% during actuator motion. The accuracy of active cannula control was evaluated in benchtop trials using an external optical tracking system with RMS error in tip placement of 1.00 mm. Preliminary phantom trials of three active cannula placements in the MRI scanner showed cannula trajectories that agree with our kinematic model, with a RMS tip placement error of 0.61 - 2.24 mm.
  • Design and Analysis of 6 DOF Handheld Micromanipulator Authors: Yang, Sungwook; MacLachlan, Robert A.; Riviere, Cameron
    This paper presents the design and analysis of a handheld manipulator for vitreoretinal microsurgery and other biomedical applications. The design involves a parallel micromanipulator utilizing six piezoelectric linear actuators, combining compactness with a large range of motion and relatively high stiffness. Given the available force of the actuators, the overall dimension of the micromanipulator was optimized considering realistic external loads on a remote center of motion representing the point of expected contact with the sclera of the eye during microsurgery. Based on optimization and workspace analysis, a benchtop version of the micromanipulator was built with a base diameter of 25 mm and a height of 50 mm. It provides a hemispherical workspace of 4.0 mm diameter at the tool tip. The manipulation performance of the constructed manipulator was measured under a lateral load applied at the remote center of motion. The micromanipulator tolerated side loads up to 200 mN.
  • An Impedance Control Strategy for a Hand-Held Instrument to Compensate for Physiological Motion Authors: Florez, Juan Manuel; Szewczyk, Jérôme; Morel, Guillaume
    Current trends in robotic cardiac surgery presage for allowing physiological motion compensation in beating-heart surgery. However, interacting with fast moving soft organs by means of stiff instruments/robots is challenging. This paper concerns comanipulation with a hand-held instrument, the goal being to allow the surgeon to perform low frequency motions that correspond to the surgical task while a distal part of the instrument actively moves in synchronism with the heart motion in order to guarantee that the contact is maintained. This paper explores the difficulties of implementing owimpedance control on a novel hand-held motion compensation instrument. A force feedback control strategy is proposed and evaluated experimentally on a simulated surgical scene. Taking advantage of the sensory capacities of the prototype resented, a successful modulation of the dynamics of interaction is reached. Conclusive results on the performances of the system and possibilities of future improvements are given.