Methods and systems are described for controlling movement of a continuum robot that includes a plurality of independently controlled segments along the length of the continuum robot. The continuum robot is inserted into a cavity of unknown dimensions or shape. A plurality of forces acting upon the continuum robot by the surrounding cavity are estimated. A positioning command indicating a desired movement of the distal end of the continuum robot is received from a manipulator control. The desired movement is augmented based, at least in part, on the estimated plurality of forces acting on the continuum robot such that movement is restricted to within safe boundaries of the surrounding cavity. The positioning of the continuum robot is then adjusted based on the augmented desired movement.

Systems and methods for safe compliant insertion and hybrid force/motion telemanipulation of continuum robots

This paper provides a theoretical framework for controlling a manipulator with hyper degrees of freedom (HDOF) . An HDOF manipulator has the capability to achieve various kinds of tasks. To make full use of its capability, shape control is proposed here; that is, not only the tip of a manipulator, but also its whole body is controlled. To formulate control objectives for shape control, the authors define a shape correspondence between an HDOF manipulator and a spatial curve that prescribes a desired shape. The shape correspondence is defined by using solutions of a nonlinear optimization problem termed the shape-inverse problem. They give theorems on the existence of the solutions, and on an existence region that allows them to convert shape-control problems into more tractable ones. A shape-regulation control problem is considered first to bring an HDOF manipulator onto a given time-invariant curve. The idea of estimating the desired curve parameters is the crucial key to solving the problem by Lyapunov design. The derived shape-regulation law includes the estimator, which infers the desired curve parameters corresponding to the desired joint positions on the curve. The idea of the desired curve-parameter estimation is also effective for shape tracking where a time-varying curvemore » is used for prescribing a moving desired shape. Considering an estimator with second-order dynamics enables the authors to find two shape-tracking control laws by utilizing conventional tracking methods in manipulator control. They show the simulation results of applying the derived shape-tracking control laws to a 20-DOF manipulator.« less

Shape Control of Manipulators with Hyper Degrees of Freedom

Hyper-redundant manipulators have a large number of redundant degrees of freedom. They have been recognized as a means to improve manipulator performance in complex and unstructured environments. However, the high degree of redundancy also causes difficulty in the calculation of workspaces and inverse kinematics. This paper develops a diffusion-based algorithm for workspace generation of hyper-redundant manipulators. This algorithm makes the workspace generation problem as simple as solving a diffusion equation which has an explicit solution. This diffusion equation is a partial differential equation defined on the motion group SE(N), and describes the evolution of the workspace density function, depending on manipulator length and kinematic properties. This paper also solves the inverse kinematics problem in an elegant way by dividing the manipulator into virtual segments and cascading the corresponding workspace densities generated by the diffusion equation.

Workspace generation of hyper-redundant manipulators as a diffusion process on SE(N)

Real-time control of redundant robotic manipulators for mobile obstacle avoidance

Workspace generation of hyper-redundant manipulators as a diffusion process on SE(N).

A hyper redundant manipulator has a very large or infinite degree of kinematic redundancy, thus it is possessed of unconventional features such as the ability to enter a narrow space while avoiding obstacles. We propose a novel obstacle avoidance technique for the hyper redundant manipulator to perform a payload location task from point to point while avoiding existing static obstacles in the environment. The scheme is based on analysis in the defined posture space, where three parameters were used to determine the hyper redundant manipulator configurations. The scheme is verified by computer simulation in case of using the model of the developed Hyper-R Arm. It shows that our method works perfect and the obstacles are well avoided globally.

M. Konno

Papers

An obstacle avoidance scheme for hyper-redundant manipulators-global motion planning in posture space