Position control system and method

1. A position control system, comprising:

a roller rotatable about a longitudinal axis thereof;

a pivotable member having a first member end rotatable about a first pivot axis and a second member end coupled to the roller wherein the second member end is rotatable about a second pivot axis spaced from the first pivot axis and wherein the first and second pivot axes are movable relative to one another;

a motor adapted to move the roller along the longitudinal axis wherein movement of the roller along the longitudinal axis causes the pivotable member to tilt the roller relative to the longitudinal axis;

a control system responsive to a sensed parameter for controlling the motor; and

a first mounting apparatus secured to an end of the roller wherein the first mounting apparatus includes a linear bearing capable of tilting movement, and a second mounting apparatus secured to another end of the roller.

2. The position control system of claim 1 , wherein the motor is coupled to the end of the roller.

3. The position control system of claim 1 , wherein the motor is coupled to the pivotable member.

4. The position control system of claim 1 , wherein the motor and the pivotable member are disposed on a same side of the roller with the first mounting apparatus and wherein the second mounting apparatus includes a linear bearing capable of tilting movement.

5. The position control system of claim 1 , wherein the pivotable member is disposed on a side of the roller with the first mounting apparatus and the motor and the second mounting apparatus are disposed on another side of the roller and wherein the second mounting apparatus includes a linear bearing capable of tilting movement.

6. The position control system of claim 1 , wherein the motor and the pivotable member are disposed on opposite sides of the roller.

7. The position control system of claim 1 , wherein the motor and the pivotable member are disposed on a same side of the roller.

8. The position control system of claim 1 , wherein the first pivot axis is fixed and the second pivot axis is movable relative to the first pivot axis.

9. The position control system of claim 1 , further including a length of material in contact with the roller wherein the sensed parameter comprises a lateral position of the length of material.

10. The position control system of claim 9 , wherein the control system comprises a controller responsive to motor position, actual edge position of the length of material, and a commanded edge position of the length of material.

11. A web position control system for controlling a position of a web to be guided by a roller rotatable about a longitudinal axis thereof, comprising:

a mounting structure that mounts the roller for rotational movement about the longitudinal axis, linear movement parallel to the longitudinal axis, and tilting movement relative to the longitudinal axis;

a pivotable linkage having a first linkage end rotatable about a first pivot axis and a second linkage end coupled to the roller wherein the second linkage end is rotatable about a second pivot axis spaced from the first pivot axis and wherein the first pivot axis is fixed and the second pivot axis is movable relative to the first pivot axis;

a motor adapted to move the roller along the longitudinal axis wherein movement of the roller along the longitudinal axis causes the pivotable member to tilt the roller relative to the longitudinal axis; and

a control system including a web position sensor for controlling the motor;

wherein the roller is supported by shaft portions and wherein the mounting structure includes a linear bearing capable of tilting movement supporting one of the shaft portions and the second linkage end is coupled to another of the shaft portions.

12. The web position control system of claim 11 , portion wherein the first linkage end is adjustably positionable within an arcuate slot to control sensitivity.

13. The web position control system of claim 12 , wherein the control system is responsive to a motor position sensor that senses motor position.

14. A method of controlling lateral position of a web traveling over a roller wherein the roller is mounted for rotation about a longitudinal axis by first and second opposed shaft portions, the method comprising the steps of:

providing a linkage having a first end rotatable about a fixed axis and a second end rotatable about a movable axis spaced from the fixed axis wherein the second end of the linkage is coupled to the roller;

providing a mounting structure that mounts the roller for rotational movement about the longitudinal axis, linear movement parallel to the longitudinal axis, and tilting movement relative to the longitudinal axis and further including the step of providing a linear bearing capable of tilting movement supporting the first shaft portion;

providing a motor coupled to one of the first and second shaft portions and adapted to move the roller along the longitudinal axis wherein movement of the roller along the longitudinal axis causes the linkage to tilt the roller relative to the longitudinal axis;

sensing the lateral position of the web; and

controlling the motor in response sensed lateral position of the web in turn to control lateral web position.

15. The method of claim 14 , wherein the linkage is coupled to the second shaft portion.

16. The method of claim 14 , wherein the step of sensing comprises the step of providing a web edge position sensor and the step of controlling comprises the step of providing a control system responsive to the web edge position sensor and a command signal representing a commanded web edge position.

17. The method of claim 16 , wherein the control system is further responsive to a signal representing a position of the motor.