scholarly journals Vision-based kinematic calibration of a H4 parallel mechanism

2004 ◽  
Author(s):  
P. Renaud ◽  
N. Andreff ◽  
F. Marquet ◽  
P. Martinet
Keyword(s):  
Parallel Mechanism ◽  
Kinematic Calibration

Vision‐based kinematic calibration of an H4 parallel mechanism: practical accuracies

2004 ◽  
Vol 31 (3) ◽  
pp. 273-283 ◽  
Author(s):  
Nicolas Andreff ◽  
Pierre Renaud ◽  
Philippe Martinet ◽  
Franc¸ois Pierrot
Keyword(s):  
Parallel Mechanism ◽  
Kinematic Calibration

Kinematic Calibration for Redundantly Actuated Parallel Mechanisms

2004 ◽  
Vol 126 (2) ◽  
pp. 307-318 ◽  
Author(s):  
Jay il Jeong ◽  
Dongsoo Kang ◽  
Young Man Cho ◽  
Jongwon Kim
Keyword(s):  
Optimization Algorithm ◽  
Parallel Mechanism ◽  
Kinematic Calibration ◽  
Parallel Mechanisms ◽  
Geometrical Constraint ◽  
Kinematic Parameters ◽  
Angle Error ◽  
Calibration Algorithm ◽  
Redundantly Actuated

We present a new kinematic calibration algorithm for redundantly actuated parallel mechanisms, and illustrate the algorithm with a case study of a planar seven-element 2-degree-of-freedom (DOF) mechanism with three actuators. To calibrate a nonredundantly actuated parallel mechanism, one can find actual kinematic parameters by means of geometrical constraint of the mechanism’s kinematic structure and measurement values. However, the calibration algorithm for a nonredundant case does not apply for a redundantly actuated parallel mechanism, because the angle error of the actuating joint varies with position and the geometrical constraint fails to be consistent. Such change of joint angle error comes from constraint torque variation with each kinematic pose (meaning position and orientation). To calibrate a redundant parallel mechanism, one therefore has to consider constraint torque equilibrium and the relationship of constraint torque to torsional deflection, in addition to geometric constraint. In this paper, we develop the calibration algorithm for a redundantly actuated parallel mechanism using these three relationships, and formulate cost functions for an optimization algorithm. As a case study, we executed the calibration of a 2-DOF parallel mechanism using the developed algorithm. Coordinate values of tool plate were measured using a laser ball bar and the actual kinematic parameters were identified with a new cost function of the optimization algorithm. Experimental results showed that the accuracy of the tool plate improved by 82% after kinematic calibration in a redundant actuation case.

Kinematic Calibration of a 3rRPS Metamorphic Parallel Mechanism

2020 ◽  
Author(s):  
Xuheng Chai ◽  
Latifah Nurahmi ◽  
Jian S. Dai ◽  
Dongming Gan
Keyword(s):  
Motion Capture ◽  
Parallel Mechanism ◽  
Optimization Problems ◽  
Calibration Method ◽  
Kinematic Calibration ◽  
External Device ◽  
Unknown Parameters ◽  
Constraint Equations ◽  
Search Optimization ◽  
Base Platform

Abstract In this paper, a kinematic calibration method is developed for a 3rRPS metamorphic parallel mechanism with respect to all unknown parameters. Each limb of the 3rRPS mechanism is composed of (rR), P, and S joints. Two joints are actuated, namely P and r joints, hence the mechanism is able to switch between the 3RPS parallel mechanism and 3US parallel mechanism. The geometric constraint equations of the 3rRPS mechanism are initially established. Then, the optimization problems for the base, platform and actuated prismatic lengths during given trajectory are formulated by using the global search optimization algorithm. A physical model of the 3rRPS metamorphic parallel mechanism is built and an experiment is setup to validate the proposed calibration and optimization models. The external device, i.e., the OptiTrack is used during the experiment for motion capture system. All unknown parameters are identified and optimized by dint of the geometric properties of this mechanism and nonlinear optimization algorithms. The experimental results demonstrate that the proposed calibration method is valid and effective.

scholarly journals Kinematic Calibration of a 2-DoF Over-Constrained Parallel Mechanism Using Real Inverse Kinematics

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 67752-67761 ◽  
Author(s):  
Tao Sun ◽  
Binbin Lian ◽  
Jiateng Zhang ◽  
Yimin Song
Keyword(s):  
Inverse Kinematics ◽  
Parallel Mechanism ◽  
Kinematic Calibration
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