Inverted Operation Gripper for Robot Fabrication

The paper introduces the use of an internal blind-hole gripping method for robotic fabrication processes. This method defines its novelty and position in timber research through state-of-the-art research exploring current robotic fabrication techniques and methods. Using existing industry components and parts, we created a modular gripping system for the repetitive gripping of timber elements. Utilizing pre-drilled cylindrical holes, the internal expanding action of the gripper self-locates the part centrally through the three points of engagement, thus helping increase precision and the repeatability of the assembly during robot use. Physical pull-out testing was conducted for validation and collection of empirical data with a focus on comparing different depths and thus contact area of the gripper about the holding force produced. Through the findings of the physical pull-out tests, we propose a novel automated gripper design and robotic setup method for use in robotic timber research and fabrication. A theoretical demonstrator is also proposed based on implementing this new method in a research scenario. When compared to the literature on forces produced from timber fabrication techniques such as cutting with a circular saw blade or drilling, we demonstrate the gripper's typical grip strength to well exceed the force requirements to cut timber elements precisely. In conclusion, the research conducted in this paper proves the efficacy and security of blind hole gripping using inverted operation for improving fabrication, automation, and efficiency of robotic timber manufacturing.