Why is measuring of balancing speed of the component very important in a balancing machine?

Balancing machine is an industrial machine. The machine is located in a factory environment along the process line. Many types of industrial noises electrical, mechanical, magnetic will exist in an industrial environment. Besides this balancing machine has drive elements like motors, pulleys, belts which also rotate along with the component. The component is mounted on rollers, and rollers also rotate along with the component. The transducers will pick up signals from all rotating elements. The electronics of the balancing machine needs a reference signal to extract the unbalance signal of the component being balanced. The speed signal of the component being balanced provides the reference for signal extraction. In older stroboscope machines, it can be observed that the unbalance location will start shifting / oscillating over a wide angle when balancing is done. In modern machines with phase lock loop, the shift of angle is reduced to insignificant levels.