In this paper we address the problem of identifying the property of the singularity loci of a class of 6/6-Gough–Stewart manipulators in which the moving and base platforms are two similar semiregular hexagons. After constructing the Jacobian matrix of this class of 6/6-Gough–Stewart manipulators according to the theory of statical equilibrium, we derive a cubic polynomial expression in the mov...

One of the most important approaches in the scientific research concerning the increase of the positioning accuracy is the use of parallel structures. Parallel kinematic structures have a series of advantages that makes them adequate for the mini-robots construction: actuator positioning on the seating, miniaturization, stiffness, positioning precision and repeatability, actuators separation fr...

This paper characterizes geometrically the singularities of limited DOF parallel manipulators. The geometric conditions associated with the dependency of six Plücker vector of lines (finite and infinite) constituting the rows of the inverse Jacobian matrix are formulated using GrassmannCayley algebra. Manipulators under consideration do not need to have a passive spherical joint somewhere in ea...

Parallel manipulators, also called parallel kinematics machines (PKM), enable robotic solutions for highly dynamic handling and machining applications. The safe accurate design control necessitates high-fidelity dynamics models. Such modeling approaches have already been presented PKM with simple limbs (i.e. each limb is a serial kinematic chain). A systematic approach complex that possess loop...

In our previous work (2008, “Optimal Force Generation in Parallel Manipulators for Passing through the Singular Positions,” Int. J. Robot. Res., 27(8), pp. 967–983), the dynamic properties of rigid-link parallel manipulators, in the presence of type 2 singularities, have been studied. It was shown that any parallel manipulator can pass through the singular positions without perturbation of moti...

The aim of this paper is to characterize the moveability of fully-parallel manipulators in the presence of obstacles. Fully parallel manipulators are used in applications where accuracy, stiffness or high speeds and accelerations are required [1]. However, one of its main drawbacks is a relatively small workspace compared to the one of serial manipulators. This is due mainly to the existence of...