Design and development of passive folded-beam vibration isolators for robotic reworking in the automotive sector

Abstract

This thesis presents the design, development, and validation of passive vibration isolators for robotic reworking operations in the automotive sector. Industrial robots are increasingly deployed to replace tedious, repetitive, and physically demanding finishing tasks traditionally performed by human workers, and several automation solutions already exist in this domain. However, most of these solutions give limited attention to vibration effects at the tool, even though such disturbances can reduce accuracy, degrade surface quality, and destabilise force control. This study addresses this gap by focusing specifically on vibration isolation at the end-effector level, proposing passive structural solutions to improve robotic finishing performance.To establish the operating requirements, the vibration disturbances generated by a representative finishing tool were experimentally characterised using a six-axis force–torque sensor. This analysis identified the dominant frequency ranges that informed the design of the isolator. Building on these findings, two passive vibration isolator concepts based on folded beam exures were developed: (i) a conventional folded-beam isolator and (ii) a novel Stewart-based folded-beam isolator, which represents a unique contribution of this work. Both designs were modelled, simulated, and optimised through modal and static analyses,then fabricated as metal prototypes. The prototypes were subsequently evaluated through bench-top vibration tests under realistic operating conditions.The results show that both isolators effectively attenuate vibration disturbances, with the Stewart-based conguration demonstrating superior performance, particularly at higher operating speeds. These ndings highlight the potential of robust, low-cost, and entirely passive structural isolators to enhance robotic nishing operations by reducing vibration effects. In doing so, they enable smoother tool operation, more stable force feedback, and improved surface quality in automotive reworking tasks.