Analytical Formula of Positive Position Solution of 2PPa-PSS 3-Translational Parallel Mechanism with Low Coupling-degree and its Numerical Application.

Most of the parallel mechanisms (PM) with low coupling degree cannot directly obtain the analytical expression of the positive position solution of the PM, which makes it difficult to carry out the follow-up research on the kinematic accuracy analysis and trajectory planning of the PM. Based on the topological structure theory, this paper analyzes the position and orientation characteristic(POC), DOF and coupling degree of 2PPa-PSS PM. Afterward, the kinematic mathematical model of 2PPa-PSS PM is established based on the order single open chain of kinematic modeling principle. The moving platform of the mechanism is set as an equilateral triangle, and the intermediate variables are solved by combining the constraints of the two chains. The positive position solution of the PM in analytical form is obtained. The correctness of the kinematic model of the mechanism is verified by numerical calculation. Then, according to the positive position solution analytical expression, we can work out the complete workspace of the PM, and the significant influence of the driving increment on the attitude change of the moving platform is analyzed by using the analysis method based on the orthogonal test. According to the results of orthogonal experiment, the best driving range of the mechanism is obtained. [ABSTRACT FROM AUTHOR]