Algorithmic singularities avoidance in task-priority based controller for redundant manipulators
03 Dec 2003-Vol. 4, pp 3570-3574
TL;DR: The proposed approach uses a secondary task correction and a successive task projection in order to maintain the measure of manipulability of the correspondent space augmentation approach over a minimum value.
Abstract: In this paper we describe an online solution for avoiding the occurrence of both algorithmic and kinematic singularities in task-priority based kinematic controllers of robotic manipulators. The proposed approach uses a secondary task correction and a successive task projection in order to maintain the measure of manipulability of the correspondent space augmentation approach over a minimum value. It shows a gain in performance and a better task error especially when working in proximity of singular configurations. It is particularly suitable for autonomous systems where an offline trajectory control scheme is often not applicable.
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TL;DR: One of the first trials of autonomous intervention performed by SAUVIM in the oceanic environment is described, which consists in a sequence of autonomous tasks finalized to search for the target and to securely hook a cable to it in order to bring the target to the surface.
307 citations
TL;DR: This paper presents a novel technique to integrate both the activation and deactivation of tasks and the inequality control objectives in the priority based control, called iCAT (inequality control objectives, activations and transitions) task priority framework, which exploits novel regularization methods.
Abstract: The task priority based control is a formalism which allows to create complex control laws with nice invariance properties, i.e. lower priority tasks do not affect the execution of higher priority ones. However, the classical task priority framework (Siciliano and Slotine) lacked the ability of enabling and disabling tasks without causing discontinuities. Furthermore, tasks corresponding to inequality control objectives could not be efficiently represented within that framework. In this paper we present a novel technique to integrate both the activation and deactivation of tasks and the inequality control objectives in the priority based control. The technique, called iCAT (inequality control objectives, activations and transitions) task priority framework, exploits novel regularization methods to activate and deactivate any row of a given task in a prioritized hierarchy without incurring in practical discontinuities, while maintaining as much as possible the invariance properties of the other active tasks. Finally, as opposed to other techniques, the proposed approach has a linear cost in the number of tasks. Simulations, experimental results and a time analysis are presented to support the proposed technique.
61 citations
Additional excerpts
...Further works on achieving a task priority control robust to singularities are found in [22,34,35]....
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TL;DR: The proposed scheme considers minimum kinetic energy (MKE) and MAN criterions via two weighting factors, thus guaranteeing the final joint velocity of motion to be near zero, which is acceptable for engineering applications.
Abstract: This paper proposes and investigates a weighted velocity and acceleration minimization scheme to prevent the occurrence of high joint velocity and joint acceleration caused by the minimum acceleration norm (MAN) scheme in redundant robot manipulators. The proposed scheme considers minimum kinetic energy (MKE) and MAN criterions via two weighting factors, thus guaranteeing the final joint velocity of motion to be near zero, which is acceptable for engineering applications. Joint physical constraints (i.e., joint angle limits, joint velocity limits, and joint acceleration limits) are incorporated in the formulation of the proposed scheme. The proposed scheme is reformulated as a quadratic program and then calculated by using a numerical algorithm based on linear variational inequality. Computer simulation results of a PUMA560 robot manipulator verify the efficacy and flexibility of the proposed scheme for redundancy resolution in robot manipulators. Experimental verifications conducted on a six-link planar robot manipulator demonstrate the effectiveness and physical realizability of the proposed scheme.
37 citations
Cites background from "Algorithmic singularities avoidance..."
...Digital Object Identifier 10.1109/TASE.2014.2346490 I. INTRODUCTION R EDUNDANT robot manipulators, which may simulatethe human arm, an elephant trunk, or a snake [1], [2], have more degrees-of-freedom (DOF) than necessary to perform a given end-effector primary task [3]–[5]....
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10 Dec 2007
TL;DR: A novel controller for task space control of balance and locomotion is developed which attempts to address singularity robustness, while minimizing discontinuities created by constraint switching.
Abstract: This paper addresses locomotion with active balancing, via task space control with prioritization. The center of gravity (COG) and foot of the swing leg are treated as task space control points. Floating base inverse kinematics with constraints is employed, thereby allowing for a mobile platform suitable for locomotion. Different techniques of task prioritization are discussed and we clarify differences and similarities of previous suggested work. Varying levels of prioritization for control are examined with emphasis on singularity robustness and the negative effects of constraint switching. A novel controller for task space control of balance and locomotion is developed which attempts to address singularity robustness, while minimizing discontinuities created by constraint switching. Controllers are evaluated using a quadruped robot simulator engaging in a locomotion task.
31 citations
Cites background or methods from "Algorithmic singularities avoidance..."
...Task-priority control of redundant manipulators have been studied in several papers [4], [5], [6], [7], [ 8 ]....
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...By using a manipulability measure, [ 8 ] is able to show that algorithmic singularities in (14) will not occur if the augmented Jacobian in (12) is not singular....
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14 Jul 2016
TL;DR: In this paper, the authors present a study of the relationship between the authorship of the authors and the authors of the paper, Faculdade de Tecnologia, Departamento de Engenharia Eletrica, Brazil.
Abstract: Tese (doutorado) — Universidade de Brasilia, Faculdade de Tecnologia, Departamento de Engenharia Eletrica, 2016.
13 citations
References
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TL;DR: In this article, a measure of manipulability of robotic mechanisms in positioning and orienting end-effectors has been proposed and the best postures of various types of manipulators are given, and a four degree-of-freedom finger is considered from the viewpoint of the measure.
Abstract: This paper discusses the manipulating ability of robotic mechanisms in positioning and orienting end-effectors and proposes a measure of manipulability. Some properties of this measure are obtained, the best postures of various types of manipulators are given, and a four-degree-of-freedom finger is considered from the viewpoint of the measure. The pos tures somewhat resemble those of human arms and fingers.
2,321 citations
"Algorithmic singularities avoidance..." refers background in this paper
...Yoshikawa [4] proposed a continuous measure that evaluates the kinematic quality of robot mechanism:...
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Book•
01 Feb 1990
TL;DR: Advanced robotics: redundancy and optimization, Advanced robotics: redundancies and optimization , مرکز فناوری اطلاعات و £1,000,000 کسورزی .
Abstract: Advanced robotics: redundancy and optimization , Advanced robotics: redundancy and optimization , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
1,137 citations
1,096 citations
"Algorithmic singularities avoidance..." refers methods in this paper
...The same experiment has been executed with the singular robust inverse [8]....
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01 Jan 1986
TL;DR: To overcome the difficulties encountered near kinematic singularities, the exact inverse problem is reformulated as a damped least-squares problem, which balances the error in the solution against the size of the solution.
Abstract: Inverse kinematic solutions are used in manipulator controllers to determine corrective joint motions for errors in end-effector position and orientation. Previous formulations of these solutions, based on the Jacobian matrix, are inefficient and fail near kinematic singularities. Vector formulations of inverse kinematic problems are developed that lead to efficient computer algorithms. To overcome the difficulties encountered near kinematic singularities, the exact inverse problem is reformulated as a damped least-squares problem, which balances the error in the solution against the size of the solution. This yields useful results for all manipulator configurations.
812 citations
01 Jun 1997
TL;DR: A new task-priority redundancy resolution technique is developed that overcomes the effects of algorithmic singularities and is applied to a seven-degree-of-freedom manipulator in numerical case studies to demonstrate its effectiveness.
Abstract: Practical application of the task-priority redundancy resolution technique must deal with the occurrence of kinematic and algorithmic singularities. The aim of this paper is twofold. First, the application of existing singularity-robust methods to the case of kinematically redundant arms is studied. Then, a new task-priority redundancy resolution technique is developed that overcomes the effects of algorithmic singularities. Computational aspects of the solutions are also considered in view of real-time implementation of a kinematic control algorithm. The method is applied to a seven-degree-of-freedom manipulator in numerical case studies to demonstrate its effectiveness.
647 citations