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Kinematics and the Implementation of an Elephant's Trunk Manipulator and Other Continuum Style Robots
 Journal of Robotic Systems
, 2003
"... Traditionally, robot manipulators have been a simple arrangement of a small number of serially connected links and actuated joints. Though these manipulators prove to be very effective for many tasks, they are not without their limitations, due mainly to their lack of maneuverability or total degree ..."
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Cited by 40 (11 self)
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Traditionally, robot manipulators have been a simple arrangement of a small number of serially connected links and actuated joints. Though these manipulators prove to be very effective for many tasks, they are not without their limitations, due mainly to their lack of maneuverability or total degrees of freedom. Continuum style (i.e. continuous “backbone”) robots on the other hand, exhibit a wide range of maneuverability, and can have a large number of degrees of freedom. The motion of continuum style robots is generated through the bending of the robot over a given section; unlike traditional robots where the motion occurs in discrete locations, i.e. joints. The motion of continuum manipulators is often compared to that of biological manipulators such as trunks and tentacles. These continuum style robots can achieve motions that could only be obtainable by a conventionally designed robot with many more degrees of freedom. In this paper we present a detailed formulation and explanation of a novel kinematic model for continuum style robots. The design, construction, and implementation of our continuum style robot called the Elephant Trunk Manipulator is presented. Experimental results are then provided to verify the legitimacy of our model when applied to our physical manipulator. We also provide a set of obstacle avoidance experiments that help to exhibit the practical implementation of both our manipulator and our kinematic model. I.
Path planning for deformable linear objects
 IEEE Transactions on Robotics
"... Abstract—We present a new approach to path planning for deformable linear (onedimensional) objects such as flexible wires. We introduce a method for efficiently computing stable configurations of a wire subject to manipulation constraints. These configurations correspond to minimalenergy curves. B ..."
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Cited by 39 (0 self)
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Abstract—We present a new approach to path planning for deformable linear (onedimensional) objects such as flexible wires. We introduce a method for efficiently computing stable configurations of a wire subject to manipulation constraints. These configurations correspond to minimalenergy curves. By restricting the planner to minimalenergy curves, the execution of a path becomes easier. Our curve representation is adaptive in the sense that the number of parameters automatically varies with the complexity of the underlying curve. We introduce a planner that computes paths from one minimalenergy curve to another such that all intermediate curves are also minimalenergy curves. This planner can be used as a powerful local planner in a samplingbased roadmap method. This makes it possible to compute a roadmap of the entire “shape space, ” which is not possible with previous approaches. Using a simplified model for obstacles, we can find minimalenergy curves of fixed length that pass through specified tangents at given control points. Our work has applications in cable routing, and motion planning for surgical suturing and snakelike robots. Index Terms—Deformation, differential geometry, flexible manipulation, flexible object representation, minimalenergy curves, modeling, motion planning, path planning. I.
A Mobile Hyper Redundant Mechanism for Search and Rescue Tasks
 In Proc. IEEE/RSJ Intl. Conf. on Intelligent Robots and Systems
, 2003
"... Abstract In this work we introduce a new concept of a search and rescue robotic system that is composed of an elephant trunklike robot mounted on a mobile base. This system is capable not only of inspecting areas reachable by the mobile base but also to inspect unreachable areas such as small crac ..."
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Cited by 31 (2 self)
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Abstract In this work we introduce a new concept of a search and rescue robotic system that is composed of an elephant trunklike robot mounted on a mobile base. This system is capable not only of inspecting areas reachable by the mobile base but also to inspect unreachable areas such as small cracks, and pipes, using the camera mounted on its elephant trunk robot. In the report we describe the mechanical structure of the elephant trunk robot, the kinematic analysis of the structure, the robot control, and its human interface systems. I.
On the Kinematics of Remotelyactuated Continuum Robots,’’
 Proceedings of the 2000 IEEE International Conference Robotics and Automation 3,
, 2000
"... Abstract Over the past several years, there has been a rapidly expanding ..."
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Cited by 24 (10 self)
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Abstract Over the past several years, there has been a rapidly expanding
Dynamic Rolling for a Modular Loop Robot
"... Summary. Reconfigurable modular robots use different gaits and configurations to perform various tasks. A rolling gait is the fastest currently implemented gait available to a modular robot for traversal of level ground. In this work, we analyze and implement a sensorbased feedback controller to ac ..."
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Cited by 20 (8 self)
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Summary. Reconfigurable modular robots use different gaits and configurations to perform various tasks. A rolling gait is the fastest currently implemented gait available to a modular robot for traversal of level ground. In this work, we analyze and implement a sensorbased feedback controller to achieve dynamic rolling for a 10 module loop robot. The controller exploits the dynamics of the system to build up momentum in each step by specifying a desired global shape for the robot at touchdown. Energy is input into the system both by raising the height of the center of mass of the robot and moving the position of center of mass with respect to the ground to maximize the moment arm due to gravity. Using simulation and experimental results, we show how the desired shape can be varied to achieve higher terminal velocities. Through simulation, we also show rounder shapes have lower specific resistance and are thus more efficient. 1
Terminatorbot: A Novel Robot with DualUse Mechanism for Locomotion and Manipulation
 IEEE/ASME Transactions on Mechatronics
, 2005
"... system, TerminatorBot, a novel, centimeterscale crawling robot has been developed to address applications in surveillance, searchandrescue, and planetary exploration. Its two 3 degreeoffreedom arms, which stow inside the cylindrical body for ballistic deployment and protected transport, comprise ..."
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Cited by 20 (14 self)
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system, TerminatorBot, a novel, centimeterscale crawling robot has been developed to address applications in surveillance, searchandrescue, and planetary exploration. Its two 3 degreeoffreedom arms, which stow inside the cylindrical body for ballistic deployment and protected transport, comprise a dualuse mechanism for manipulation and locomotion. The intended applications require a small, rugged, and lightweight robot, hence the desire for dualuse. TerminatorBot’s unique mechanism provides mobility and fine manipulation on a scale currently unavailable. To facilitate manipulation, we have also developed a specialized force/torque sensor. This new sensor design has a biased distribution of flexures, which equalizes force and torque sensitivities at the operational point. This paper describes the mechanism and design of TerminatorBot, the specialized force/torque sensor, and the mechanismspecific gaits. Index Terms — robotics, mobile manipulation, force sensor, TerminatorBot
Differentiable and Piecewise Differentiable Gaits for Snake Robots
 In Proceedings of the International Conference on Intelligent Robots and Systems
, 2007
"... Abstract—This paper describes a series of gaits which we developed for a free crawling snake robot. Snake robots, a class of hyperredundant mechanisms, can use their many degrees of freedom to achieve a variety of locomotion capabilities. Like their biological counterparts, snake robots locomote us ..."
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Cited by 18 (6 self)
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Abstract—This paper describes a series of gaits which we developed for a free crawling snake robot. Snake robots, a class of hyperredundant mechanisms, can use their many degrees of freedom to achieve a variety of locomotion capabilities. Like their biological counterparts, snake robots locomote using cyclic motions called gaits. These cyclic motions directly control the snake robot’s internal degrees of freedom which causes a net motion (e.g. sining moves the robot forward, strafing moves the robot laterally, and spinning rotates the robot about its center). The gaits described in this paper fall into two categories: differentiable and piecewise differentiable. The differentiable gaits, as their name suggests, can be described by a differentiable function whereas the piecewise cannot. This paper describes the functions we prescribed for gait generation and our experiences in making these robots operate in real experiments. I.
Inverse kinematics of concentric tube steerable needles
 IEEE International Conference on Robotics and Automation
, 2007
"... AbstractPrior papers have introduced steerable needles composed of precurved concentric tubes. The curvature and extent of these needles can be controlled by the relative rotation and translation of the individual tubes. Under certain assumptions on the geometry and design of these needles, the fo ..."
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Cited by 14 (3 self)
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AbstractPrior papers have introduced steerable needles composed of precurved concentric tubes. The curvature and extent of these needles can be controlled by the relative rotation and translation of the individual tubes. Under certain assumptions on the geometry and design of these needles, the forward kinematics problem can be solved in closed form by means of algebraic equations. The inverse kinematics problem, however, is not as straightforward owing to the nonlinear map between relative tube displacements and needle tip configuration as well as to the multiplicity of solutions as the number of tubes increases. This paper presents a general approach to solving the inverse kinematics problem using a pseudoinverse solution together with gradients of nullspace potential functions to enforce geometric and mechanical constraints.
Kinematic state estimation and motion planning for stochastic nonholonomic systems using the exponential map
, 2008
"... A nonholonomic system subjected to external noise from the environment, or internal noise in its own actuators, will evolve in a stochastic manner described by an ensemble of trajectories. This ensemble of trajectories is equivalent to the solution of a Fokker–Planck equation that typically evolves ..."
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Cited by 13 (5 self)
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A nonholonomic system subjected to external noise from the environment, or internal noise in its own actuators, will evolve in a stochastic manner described by an ensemble of trajectories. This ensemble of trajectories is equivalent to the solution of a Fokker–Planck equation that typically evolves on a Lie group. If the most likely state of such a system is to be estimated, and plans for subsequent motions from the current state are to be made so as to move the system to a desired state with high probability, then modeling how the probability density of the system evolves is critical. Methods for solving FokkerPlanck equations that evolve on Lie groups then become important. Such equations can be solved using the operational properties of group Fourier transforms in which irreducible unitary representation (IUR) matrices play a critical role. Therefore, we develop a simple
Path Planning for Minimal Energy Curves of Constant Length
 in Proc. IEEE Int. Conf. Robot. Autom
, 2004
"... In this paper we present a new path planning technique for a flexible wire. We first introduce a new parametrization designed to represent lowenergy configurations. Based on this parametrization we can find curves that satisfy endpoint constraints. Next, we present three different techniques for mi ..."
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Cited by 12 (4 self)
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In this paper we present a new path planning technique for a flexible wire. We first introduce a new parametrization designed to represent lowenergy configurations. Based on this parametrization we can find curves that satisfy endpoint constraints. Next, we present three different techniques for minimizing energy within the selfmotion manifold of the curve. We introduce a local planner to find smooth minimal energy deformations for these curves that can be used by a general path planning algorithm. Using a simplified model for obstacles, we can find minimal energy curves of fixed length that pass through specified tangents at given control points. Finally, we show that the parametrization introduced in this paper is a good approximation of true minimal energy curves. Our work has applications in surgical suturing and snakelike robots.