Dynamic stiffness control and acceleration scheduling for the active balancing control of a Jeffcott-like rotor system

This paper considers the problem of active balancing control on a Jeffcott-like rotor supported on two ball bearings. One of them can be automatically moved to control the effective rotor length and, as an inmediate consequence, the rotor stiffness. This control squeme is also combined with the knowledge of the rotor frequency response as well as a local rotor speed controller to compensate synchronous perturbations. The asymmetric motion of the disk, due to the motion of one of the supporting bearings, leads to a nonlinear and coupled model of six degree of fredoom, including gyroscopics effects, which differs from the so-called Jeffcott rotor. The dynamic stiffness control, based on frecuency analysis, speed control and acceleration scheduling, is used for the active balancing control. Such control is able to reduce and stabilize the amplitude response while passing (run-up or coast down) through its first critical speed. Some numerical simulations are included to illustrate the unbalance compensation properties and robustness when the rotor is started and operated over the first critical speed.