Feature extraction from multi-axis MEMS sensors for unbalance detection in non-stationary rotating conditions

Conventional rotor balancers are driven by electric motors that maintain the machine rotor/shaft assembly at a constant rotational speed throughout the whole unbalance detection process. The present work expands the operating field of balancing machines, providing an algorithm enabling rotor balancing in non-stationary coasting-down regions, i.e., during the deceleration phase of the rotor/shaft assembly. In this context, the action of the electric motor, or of any other actuator, is just needed to bring the rotor/shaft assembly at the initial target rotational speed, reducing the overall energy consumption. Then, the actuator is deactivated and the unbalance is detected while the rotating mass is decelerating freely. The effectiveness of the proposed unbalance detection algorithm is proven over the case study of a human-powered wheel balancer. The proposed strategy allows the effective detection of static unbalanced masses higher than or equal to 20g considering both 15′′ and 16′′ vehicle wheels.