Controller and system for controllably rotating a roll of material

1. A controller for a motor configured to rotate a roll of material, the controller comprising:

a drive speed regulator configured to generate an initial torque command based on a difference between a speed setpoint and a measured drive speed of the motor, wherein the initial torque command represents an amount of rotational force currently applied to the roll of material by the motor;

an observer module configured to estimate a density error of the roll of material based at least in part on the initial torque command and the speed setpoint, wherein the initial torque command is adjusted based on the density error to obtain a total torque command, wherein the observer module is enabled if the roll of material is one of accelerating and decelerating, and wherein the observer module is disabled if the roll of material is being maintained at a substantially constant speed; and

a torque regulator configured to control the motor based on the total torque command, wherein a Coulomb friction torque command is generated based on an expected amount of Coulomb friction experienced by the motor, wherein the total torque command is further based on the Coulomb friction torque command.

2. The controller as set forth in claim 1 , wherein the observer module is configured to transmit the estimated density error to an inertia calculation module configured to calculate an inertia of the roll of material.

3. The controller as set forth in claim 2 , wherein the inertia calculation module is configured to generate an inertia torque command based on the calculated inertia of the roll of material.

4. The controller as set forth in claim 3 , wherein a feedforward torque command is added to the initial torque command to obtain the total torque command.

5. The controller as set forth in claim 4 , wherein the feedforward torque command is based at least partially on the inertia torque command.

6. The controller as set forth in claim 5 , wherein a damping torque command is generated based on an expected amount of damping friction of the motor, the feedforward torque command being further based on the damping torque command.

7. The controller as set forth in claim 6 , wherein the feedforward torque command being further based on the Coulomb friction torque command.

8. A web handling system for use with a roll of material, the web handling system comprising:

a motor configured to one of unwind and wind the roll of material; and

a controller configured to control a drive speed of the motor, the controller comprising:

a drive speed regulator configured to generate an initial torque command based on a difference between a speed setpoint and a measured drive speed of the motor, wherein the initial torque command represents an amount of rotational force currently applied to the roll of material by the motor;

an observer module configured to estimate a density error of the roll of material based at least in part on the initial torque command and the speed setpoint, wherein the initial torque command is adjusted based on the density error to obtain a total torque command, wherein the observer module is enabled if the roll of material is one of accelerating and decelerating, and wherein the observer module is disabled if the roll of material is being maintained at a substantially constant speed; and

a torque regulator configured to control the motor based on the total torque command, wherein a Coulomb friction torque command is generated based on an expected amount of Coulomb friction experienced by the motor, wherein the total torque command is further based on the Coulomb friction torque command.

9. The web handling system as set forth in claim 8 , wherein the observer module is configured to transmit the estimated density error to an inertia calculation module configured to calculate an inertia of the roll of material.

10. The web handling system as set forth in claim 9 , wherein the inertia calculation module is configured to generate an inertia torque command based on the calculated inertia of the roll of material.

11. The web handling system as set forth in claim 10 , wherein a feedforward torque command is added to the initial torque command to obtain the total torque command.

12. The web handling system as set forth in claim 11 , wherein the feedforward torque command is based at least partially on the inertia torque command.

13. The web handling system as set forth in claim 12 , wherein a damping torque command is generated based on an expected amount of damping friction of the motor, the feedforward torque command being further based on the damping torque command.

14. The web handling system as set forth in claim 13 , wherein the feedforward torque command being further based on the Coulomb friction torque command.