A two-nozzle cable-driven parallel robot for 3D printing building construction: path optimization and vibration analysis

This paper proposes a novel two-nozzle cable-driven parallel robot (CDPR) for 3D printing building construction. This system has two independently moving nozzles mounted on the existing printing head. Thus, the printing time can be reduced dramatically with this system as the travel path of the printing head can be reduced to almost half thanks to those two nozzles that print almost half of the printing contour. To fully take advantage of two nozzle structures effectively, the path of the printing head is optimized to secure the minimum travel length of both the printing head and two nozzles. The smoothness of the optimal path is secured by applying the non-uniform rational B-splines (NURBS). In addition, free vibration of the proposed CDPR printer’s structure is analyzed to improve the printing quality and help the control of the proposed CDPR by using a finite element formulation of cables of the proposed robot. From the analysis results, the critical design guide—stiffness of the proposed structure could be raised by increasing the minimum cable tension in the tension distribution optimization algorithm—was obtained as well.