Type Synthesis and Typical Application of 1T2R-Type Parallel Robotic Mechanisms

Abstract

This paper focuses on the 1T2R-type (T: translational DOF; R: rotational DOF) parallel robotic mechanisms (PKMs) and discusses their type synthesis and typical application in five-axis machine tools. Based on Grassmann line geometry and atlas method, a systematic method dealing with the type synthesis of lower mobility PKMs is introduced. The Blanding rules and generalized Blanding rules, which are the criterions in realizing the mutual conversion between the freedom-space atlas and the constraintspace atlas, are summarized and discussed in detail. Thereafter, the entire procedure of the type synthesis is presented, and the type synthesis of 1T2R PKMs is carried out. Based on the synthesis results, a five-axis hybrid mechanism is proposed and a machine tool is developed consequently. The type synthesis method presented in this paper is intuitive and concise and can be used in the type synthesis of other lower mobility PKMs.

Type Synthesis of Parallel 2R1T Remote Center of Motion Mechanisms Based on Screw Theory

“…In screw theory, the motion of a mechanism is represented by a twist system which is composed of several twists, and the constraint for a mechanism is represented by a wrench system which is composed of several wrenches. The details about screw theory can be seen in [11][12][13].…”

“…Furthermore, the general reciprocal rules and type synthesis processes in screw theory can be found in [11][12]. However, owing to the particularity of the RCM motion pattern, the processes should be adapted for the specific synthesis problems.…”

“…However, for multi-DOF mechanisms, a widely used type synthesis method is the screw theory method. The major disadvantage of this method is that it can only synthesize instantaneous motion mechanisms [11][12][13][14].…”

Kinematics, dynamics, and control system of a new 5-degree-of-freedom hybrid robot manipulator

“…A 5-DOF hybrid mechanism, which includes a synthesized 2 translational DOFs and 1 rotational DOF (2T1R) parallel module, was developed. [6][7][8] A 3-DOF parallel platform and a X-Y table were integrated into a 5-DOF hybrid mechanism. 9 Another 5-DOF hybrid robot manipulator was proposed, which consists of a parallel mechanism (3T1R) and a rotational table.…”

“…21 These 5-DOF hybrid robot manipulators have several disadvantages. Some designs of robot manipulators are very complex, since an application of the inferior-mobility robot manipulator demands a translatable table [6][7][8] or a rotatable one. [9][10][11] Also, the problem of achieving motion control is harder for the hybrid mechanism [12][13][14][15] with redundantly actuated joints than a non-redundantly actuated one.…”