Date of Award

Winter 2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Committee Director

K. N. Kaipa

Committee Member

O. G. Kravchenko

Committee Member

S. Bawab

Abstract

Robotic drilling finds applications in diverse fields ranging from advanced manufacturing to the medical industry. Recent advances in low-cost, and human-safe, collaborative robots (e.g., Sawyer) are enabling us to rethink the possibilities in which robots can be deployed for such tedious and time-consuming tasks. This thesis presents a robotic drilling methodology with features of force-control enabled micro-drilling and human-robot collaboration to reduce programming efforts and enhance drilling performance. A Sawyer robot from Rethink Robotics, which offers safe physical interactions with a human co-worker, kinesthetic teaching, and force control, is used as the test bed. The robot’s end-effector was equipped with a Dremel drill fit into a housing, which was custom designed and 3D-printed using an Object Prime 3D-printer. The proposed approach applies human-robot collaboration in two cases. First, a human kinesthetically teaches a set of drill coordinates by physically holding the robot and guiding it to those locations. The robot then executes the drilling task by moving to these recorded locations. This thereby avoids the need to specify the drill coordinates with respect to a fixed reference frame, leading to reduction in programming effort and setup time while transitioning between different drilling jobs. Second, drilled hole quality is shown to be enhanced when a human provides nominal physical support to the robot during certain drilling tasks. An experimental analysis of the impact of force control on micro-drilling revealed that the proposed robotic system is capable of successfully drilling holes with a drill bit of 0.5 mm diameter with an error of +/- 0.05 mm, without breaking it for more than 100 holes. The proposed robotic drilling was validated in the following application domain: micro-drilling for composite repairs based on the through-thickness reinforcement (TTR) technique. For this purpose, sandwich beam samples were prepared by using pre-preg unidirectional carbon fabric face sheets with a honeycomb core, and they were subjected to four-point static loading until de-bonding occurred between the face sheet and the core. The samples were then repaired using the TTR technique, where the proposed robotic drilling was used to drill holes of 0.75 mm diameter in the damaged area of the sample and carbon fiber rods and with low-viscosity epoxy, were manually inserted into these drilled holes. The results revealed that the sandwich beam regained effective compressive strength after going through the TTR technique. Experiments also reveal the potential of the proposed robotic drilling technique in aerospace and automotive manufacturing involving drilling in complex postures and micro-drilling for orthopedic applications.

DOI

10.25777/rt8j-3s31

ISBN

9780438991743

ORCID

0000-0001-8512-3664

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