Momentum wheel stabilization for robotic machining

Industrial robots offer a low-cost, flexible, and compact alternative to conventional CNC machines for machining large components, but their low dynamic stiffness can lead to severe vibration and poor machining performance. This thesis investigates the use of momentum wheels to mitigate this harmful vibration. The interaction between structural angular motion and the angular momentum stored in the wheels generates gyroscopic reaction moments that modify the structural response without feedback control or tuned vibration absorbers. The concept was first explored using a single-wheel flexible structure, where impact testing characterized changes in receptance with increasing angular momentum. A dual-wheel milling end effector was then developed to study the effects of angular momentum magnitude, direction, and orientation relative to the structural mode shape. Milling tests measured end effector acceleration and lateral displacement, and the resulting surface roughness. The single-wheel system reduced peak dynamic compliance at the target resonance by 83%, from 20.4 μm/N to 3.4 μm/N. The dual-wheel system reproduced this effect, reducing peak dynamic compliance by up to 80%, with the response strongly dependent on wheel orientation relative to the dominant structural rotation. During milling, momentum wheel operation reduced resultant RMS acceleration by 26–64%, lateral displacement by 56–84%, and surface roughness by 26–90% across the four milling feed directions. These results demonstrate that gyroscopic reaction moments generated by momentum wheels can substantially reduce dynamic compliance and improve the machining performance of flexible structures.