Direct kinematics of 3DOF planar parallel mechanisms: A discussion

This paper presents the direct kinematic solutions of 3DOF planar parallel mechanisms, specifically of the 3RRR mechanism. The direct kinematic problem of the mechanism generally results in a polynomial solution. To obtain an analytical (closed-form) solution, it is necessary for the polynomial to b...

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Bibliographic Details
Main Authors: Oetomo, D., Liaw, H., Alici, G., Shirinzadeh, B., Zhong, Yongmin
Other Authors: Billingsley, John, ed.
Format: Conference Paper
Published: Curran Associates 2006
Online Access:http://hdl.handle.net/20.500.11937/24379
Description
Summary:This paper presents the direct kinematic solutions of 3DOF planar parallel mechanisms, specifically of the 3RRR mechanism. The direct kinematic problem of the mechanism generally results in a polynomial solution. To obtain an analytical (closed-form) solution, it is necessary for the polynomial to be of degree 4 or less. This paper presents a special configuration that reduces the polynomial solution to a 4th degree. This special configuration further decouples the direct kinematics of the position and the orientation of the end-effector into two cascaded quadratic equations. Numerical example is carried out to verify the results of this simplification. The existence of the closed-form solution would increase the accuracy of the direct kinematic solution and improves computational efficiency as numerical iterative method is not required. This result provides an efficient computational method for a very useful configuration of planar parallel manipulators.