Configuring a new educational machine tool based on hybrid kinematic mechanism

The paper shows the configuration of a new educational machine based on hybrid kinematics mechanism. The concept of a three-axis O-X hybrid mechanism is described, consisting of a single serial translational axis and a two-axis parallel mechanism that can operate in two variants, with extended form O and crossed form X-joints of the parallel mechanism. The virtual prototype of the machine was configured in a CAD/CAM environment, where simulations of the mechanism's operation were performed. A programming system for machine has been prepared that also enables program verification. An open architecture control system based on the LinuxCNC platform has been configured for control of the machine. The trial work of the machine was performed in order to verify the realized prototype and control.

External Kinematic Calibration of Hybrid Kinematics Machine Utilizing Lower-DOF Planar Parallel Kinematics Mechanisms

This paper presents the implementation of nonlinear least squares and iterative linear least squares algorithms for external kinematic calibration of a hybrid kinematics machine composed of two 3PRR planar parallel kinematics mechanisms by utilizing a laser tracker. First the hand-eye and robot-world transformations were obtained by a separable closed-form solution and refined by the nonlinear least squares. Subsequently, the geometric parameters of the machine’s mechanisms were estimated using the two algorithms. Due to the rank deficiency, we implemented the nonlinear least squares algorithm through a subset selection approach in which we performed the estimation in two steps. We iterated the closed-form solution of the linear least squares until the solution converges to the actual values. We have shown that the nonlinear least squares algorithm successfully refined the hand-eye and robot-world transformations and outperformed the iterative linear squares algorithm in the estimation of the geometric parameters of the mechanisms.

Optimized Planar 3PRR Mechanism for 5 Degrees-of-Freedom Hybrid Kinematics Manipulator

Hybrid kinematics mechanisms combines the advantages of purely serial and purely parallel kinematics mechanisms. Several hybrid kinematics mechanisms have been proposed. This paper proposes a novel hybrid kinematics mechanism using planar 3PRR planar kinematics mechanism, which can be utilized for machine tool. As the common main drawback of parallel mechanism is the workspace, the proposed mechanism has been optimized by using constrained nonlinear optimization. It is shown that the optimization gives significant improvement of the workspace area and shape.