Based on the motion equations of an unbalanced spherical rotor withcontactless suspension, three methods of MUM (mass unbalance measurement) are put forward to measurethe total mass unbalance, radical mass unbalance a...Based on the motion equations of an unbalanced spherical rotor withcontactless suspension, three methods of MUM (mass unbalance measurement) are put forward to measurethe total mass unbalance, radical mass unbalance and radical mass unbalance of the rotor. Totalmass unbalance is obtained when the unbalanced rotor plays as a simple pendulum in static situation.The pendulant period and pendulant midpoint indicate magnitude and direction of total massunbalance of the rotor respectively. Analysis of the motion equations by using the averaging methodyields that the rotor will do a special side oscillation when an auxiliary system makes the rotorspin about its pole axis which is orientating toward the local vertical. The radical mass unbalancecan be obtained by building a proper displacement sensor to sense the amplitude of the sideoscillation. Necessary analysis of the motion equations also shows that when the rotor spins at asmall angular velocity and the rotary axis is perpendicular to the vertical, the pole axis of therotor will precess slowly about the vertical by virtue of the axial mass unbalance. The axial massunbalance can be estimated from the time history of the spin vector of the rotor. Finally,measurement precision of the three methods is compared and how the external torque affects themeasurement precision for the three methods are examined.展开更多
基金This project is supported by National Defense Foundation of China (No.9.4.4).
文摘Based on the motion equations of an unbalanced spherical rotor withcontactless suspension, three methods of MUM (mass unbalance measurement) are put forward to measurethe total mass unbalance, radical mass unbalance and radical mass unbalance of the rotor. Totalmass unbalance is obtained when the unbalanced rotor plays as a simple pendulum in static situation.The pendulant period and pendulant midpoint indicate magnitude and direction of total massunbalance of the rotor respectively. Analysis of the motion equations by using the averaging methodyields that the rotor will do a special side oscillation when an auxiliary system makes the rotorspin about its pole axis which is orientating toward the local vertical. The radical mass unbalancecan be obtained by building a proper displacement sensor to sense the amplitude of the sideoscillation. Necessary analysis of the motion equations also shows that when the rotor spins at asmall angular velocity and the rotary axis is perpendicular to the vertical, the pole axis of therotor will precess slowly about the vertical by virtue of the axial mass unbalance. The axial massunbalance can be estimated from the time history of the spin vector of the rotor. Finally,measurement precision of the three methods is compared and how the external torque affects themeasurement precision for the three methods are examined.
