Development and application of a robotic manipulator system utilizing null-space control for three-dimensional printing

This paper presents the development of a robotic manipulator system for three-dimensional (3D) printing. Most closed-loop inverse kinematics (IK) methods that handle IK problems result in a robotic manipulator with a slight deviation, which may lead to inappropriate material stacking and defective objects or even damage the extruder. These methods are feasible when manipulating the motion of the robotic arm, but using these methods on the robotic arm for 3D printing can cause errors. Here, a null-space control with three potential fields to ensure completion of the primary task without disturbance, namely joint limit avoidance, singularity avoidance, and orientation error minimization, is applied to provide a safe solution. Minimizing orientation error can avoid extruder flipping, and a singular value decomposition-based singularity avoidance method is proposed to make calculations faster and more accessible. The null-space control method with three potential fields was numerically simulated. The proposed method and robotic manipulator system, conducted in freeform surface printing, were experimentally validated.

Automated summary

This paper presents the development of a robotic manipulator system for three-dimensional printing, with a focus on addressing the potential issues that may arise during the 3D printing process. The proposed null-space control method takes into account joint limits, singularities, and orientation errors to ensure a safe and reliable printing process.