Robot-assisted 3D printing of biopolymer thin shells

The design, development, and testing of a robot-assisted biopolymer thin shell free-form printing system is presented. This fused-deposition style printing system directly extrudes pellets of biomaterial and is capable of printing directly on organically shaped 3D curved surfaces. The screw extrusion method allows direct printing from pellets. The printed structure is supported by a pre-built base (a mandrel), which is manipulated by a six degree-of-freedom industrial robot arm, an ABB IRB120. This robot is used to manipulate the orientation of the support mandrel surface. The print method works by projecting a desired 2D image onto a mathematical model of the pre-built mandrel surface. This produces a 3D point path for the system to follow. These points are then converted into vectors for the robot's pose and orientation of the end effector, which ensures that the extrusion remains normal to the mandrel surface. Inverse kinematics is applied to convert the trajectory into joint positions for the robot to follow. This paper demonstrates the utility of the developed system through simulation and printing of concave surface designs.