Vision feedback based end-effector motion control of a flexible robot arm

2007 ◽  
Author(s):  
Zhao-Hui Jiang ◽  
Tsuyoshi Eguchi
Keyword(s):  
Motion Control ◽  
Robot Arm ◽  
Flexible Robot ◽  
End Effector ◽  
Vision Feedback

Control of a Flexible Robot Arm: Experimental and Theoretical Results

1987 ◽  
Vol 109 (4) ◽  
pp. 299-309 ◽  
Author(s):  
N. G. Chalhoub ◽  
A. G. Ulsoy
Keyword(s):  
Partial Evaluation ◽  
Digital Simulation ◽  
Robot Arm ◽  
Flexible Robot ◽  
Motion Controller ◽  
Positional Accuracy ◽  
Spherical Coordinate ◽  
End Effector ◽  
Theoretical Results ◽  
Observation Spillover

The operation of high precision robots is severely limited by. their manipulator dynamic deflection, which persists for a period of time after a move is completed. These unwanted vibrations deteriorate the end effector positional accuracy and reduce significantly the robot arm production rate. A “rigid and flexible motion controller” is derived to introduce additional damping into the flexible motion. This is done by using additional sensors to measure the compliant link vibrations and feed them back to the controller. The existing actuators at the robot joints are used (i.e., no additional actuators are introduced). The performance of the controller is tested on a dynamic model, developed in previous work, for a spherical coordinate robot arm whose last link only is considered to be flexible. The simulation results show a significant reduction in the vibratory motion. The important issue of control and observation spillover is examined and found to present no significant practical problems. Partial evaluation of this approach is performed experimentally by testing two controllers, a “rigid body controller” and a “rigid and flexible motion controller,” on a single joint of a spherical coordinate, laboratory robot arm. The experimental results show a significant reduction in the end effector dynamic deflection; thus partially validating the results of the digital simulation studies.

Nonlinear Regulation of End-Effector Motion for a Flexible Robot Arm

1991 ◽  
pp. 229-236 ◽  
Author(s):  
Alessandro De Luca ◽  
Leonardo Lanari ◽  
Giovanni Ulivi
Keyword(s):  
Robot Arm ◽  
Flexible Robot ◽  
End Effector ◽  
Nonlinear Regulation

Force and Motion Control of a Constrained Flexible Robot Arm

1994 ◽  
Vol 116 (3) ◽  
pp. 336-343 ◽  
Author(s):  
F. L. Hu ◽  
A. G. Ulsoy
Keyword(s):  
Vibration Control ◽  
Motion Control ◽  
Force Control ◽  
Experimental Studies ◽  
Joint Motion ◽  
Robot Arm ◽  
Flexible Robot ◽  
Force And Motion ◽  
Regulation And Tracking

The results of a study on the combined joint motion control, vibration control, and force control of a constrained rigid-flexible robot arm for both regulation and tracking are presented. A nonlinear modified Corless-Leitmann controller is proposed for control of the flexible motion using only joint actuators. Experimental studies, which demonstrate the effectiveness of the proposed method, are described.

Output Tracking for a Nonlinear Flexible Arm

1993 ◽  
Vol 115 (1) ◽  
pp. 78-85 ◽  
Author(s):  
P. Lucibello ◽  
M. D. Di Benedetto
Keyword(s):  
Rigid Motion ◽  
Inverse System ◽  
Inertial Forces ◽  
Robot Arm ◽  
Bounded Solutions ◽  
Flexible Robot ◽  
Controlled System ◽  
End Effector ◽  
Output Tracking ◽  
Flexible Arm

In this paper, an inversion-based control of the end effector of a two-link flexible robot arm is investigated. The challenge in solving this problem consists in the instability of the inverse system. Arbitrary initialization of the inverse system leads to unbounded elastic vibrations, even if along the desired trajectory the inertial forces associated with the rigid motion are bounded. We show that bounded solutions of the inverse system exist and we provide procedures for computing such solutions in the case of periodic velocities of the end effector. In particular, we consider the case of tracking an unbounded trajectory, e.g., an end point ramp. A technique for the stabilization of the trajectories to be tracked is also proposed and some numerical simulations illustrate the performance of the controlled system.

Mechatronic robot arm with active vibration absorbers

2020 ◽  
Vol 26 (13-14) ◽  
pp. 1145-1156 ◽  
Author(s):  
Karel Kraus ◽  
Zbyněk Šika ◽  
Petr Beneš ◽  
Jan Krivošej ◽  
Tomáš Vyhlídal
Keyword(s):  
Vibration Suppression ◽  
High Accuracy ◽  
Robot Arm ◽  
Frequency Range ◽  
Flexible Robot ◽  
Linear Quadratic ◽  
Mass System ◽  
End Effector ◽  
End Point ◽  
Serial Robots

Serial robots are typically able to cover large workspace, but their mass/stiffness ratio does not allow combining high accuracy and high dynamic of the end effector operations. Widely spread usage of serial robots, even for tasks such as drilling, leads to high accuracy demands through its workspace. Absolute measurement of the end point for position feedback can be challenging due to objects or even a workpiece in the workspace. Moreover, inbuilt motors of the serial robot cannot response in the frequency range high enough as vibration of the end point. Instead, an additional spring–mass system is attached to the robot to suppress vibrations. The narrow frequency range of a passive dynamic absorber can be extended with active elements between the robot and absorber. An active approach is also necessary because of robots eigenfrequencies and eigenmodes variability. The study deals with a planar flexible robot equipped with a three-degree-of-freedom planar active absorber. The absorber is tuned passively to one value of multiple eigenfrequency. The linear-quadratic regulator control with a state observer has been designed as an active absorber control algorithm. Feedback inputs are absorber body acceleration, end effector acceleration, and relative motions in three absorber actuators realized by voice coils. The end effector vibration suppression along the robot trajectory is achieved using gain scheduling of local controller’s outputs.

Free Vibrations of a Flexible Arm Attached to a Compliant Finite Hub

1988 ◽  
Vol 110 (1) ◽  
pp. 118-120 ◽  
Author(s):  
T. P. Mitchell ◽  
J. C. Bruch
Keyword(s):  
Natural Frequencies ◽  
Free Vibrations ◽  
The Other ◽  
Physical Parameters ◽  
Robot Arm ◽  
Flexible Robot ◽  
Concentrated Mass ◽  
End Effector ◽  
Flexible Arm ◽  
Free Beam

A single-joint flexible robot arm consisting of one link and carrying an end effector is modeled by a continuous, uniform, clamped-free beam having a concentrated mass at the free end and being clamped at the other end to a compliant finite hub. The first six natural frequencies are given for various ratios of physical parameters. The modal shapes are also presented along with their orthogonality relationship. The limiting cases of some of the physical parameters are discussed.

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