Control of Flexible Robot: Extension of the Computed Torque Method

Renders, Jean-Michel; Becquet, Marc; Hanus, Raymond

doi:10.1109/iros.1988.592415

Cited by 1 publication

(1 citation statement)

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“…With respect to rigid-body mechanisms, this also doubles the number of variables per link to six: position, velocity, and acceleration on both the motor and link sides. Renders's (Renders, Becquet, and Hanus 1988) extended recursive Newton-Euler (ERNE) for flexible links, which takes into account the forces and moments acting on both the rotor and link sides, was adopted and modified for the Rotabot. Compared to the classical recursive Newton-Euler (RNE), the outward iteration is extended to obtain the motor as well as the link variables, with the inward iteration computing the motor torques.…”

Section: Overall System Dynamicsmentioning

confidence: 99%

Design and Control of a Novel 3-DOF Flexible Robot, Part 2

Arocena

Daniel

1998

The International Journal of Robotics Research

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This paper aims to present the design of a practical controller for a flexible, industrially competent, robot arm. The language used is that of a practicing control engineer, with emphasis on the physical insights useful to the designer during the design process. This contrasts with most experimental results presented in the literature, which are usually for one-and two-link planar arms and are amenable to closed-form analysis and simulation. Such arms also manifest limited performance with respect to rigid-body manipulators, and underline the difficulties in extending controller design to more than two flexible links. Furthermore, experimenters invariably rely on the efficacy of the control algorithm, rarely exploiting their understanding of control theory to add mechanical design features to ease the control task. The work presented in this paper centers on a three-link (spatial) flexible and industry-sized prototype arm, the Rotabot, and the purpose is to demonstrate that the control task can be simplified by using control-theory-driven mechanical design. The special design features of the Rotabot facilitating ease of arm dynamic control are presented in a companion paper, Part 1. The final control task, despite the care taken with the arm design, was hampered by driver nonlinearities such as torque ripple, Coulombic friction, and pure time delays within the commutation circuitry of the motors. The use of direct drive means that drive nonlinearities, which tend to have high bandwidths, are closely coupled to the vibration characteristics of the arm—a problem that tends not to arise in geared robots. These nonideal drive characteristics had to be dealt with by the controller. Simulation and experimental results are presented to demonstrate the feasibility of controlling such an arm and pave the way for a new practical research path on flexible manipulators.

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Section: Overall System Dynamicsmentioning

confidence: 99%