Actuator assembly including magnetic sensor system for vibrationless position feedback

1. An actuator assembly for moving a device, the actuator assembly comprising:

a stator component;

a mover component that moves relative to the stator component along a mover axis, the mover component being coupled to the device so that the device moves relative to the stator component as the mover component is moved relative to the stator component along the mover axis;

a measurement system that monitors movement of the mover component relative to the stator component, the measurement system including (i) a magnet assembly that is coupled to and moves with the mover component, the magnet assembly producing a consistent magnetic field that moves relative to the stator component as the mover component moves relative to the stator component; and (ii) a plurality of spaced apart sensors that are fixed in position relative to the stator component, the sensors being positioned along a path of the mover component such that at least two of the sensors are positioned within an active region of the magnetic field at all times as the mover component moves relative to the stator component along the mover axis, the sensors being configured to sense changes in the magnetic field produced by the magnet assembly as the mover component moves along the mover axis; and wherein each sensor is a transducer that generates a sensor signal that varies its output voltage in response to the changing magnetic field from the magnet assembly as the mover component is moved relative to the sensors;

an actuator that moves the mover component and the magnet assembly relative to the stator component while the magnet assembly is being used for monitoring movement of the mover component relative to the stator component; and

a signal processor that receives the sensor signals and estimates a position of the mover component along the mover axis at a given point in time based at least in part on the sensor signals from the at least two of the sensors that are positioned within the active region of the magnetic field at the given point in time.

2. The actuator assembly of claim 1 wherein the plurality of sensors are aligned and spaced apart along a sensor axis that is substantially parallel to the mover axis.

3. The actuator assembly of claim 1 wherein the mover component only moves along the mover axis relative to the stator component.

4. The actuator assembly of claim 3 wherein the stator component includes a tubular-shaped stator body, and the mover component includes a piston disc that is positioned within the stator body and is configured to move along the mover axis relative to the stator body.

5. The actuator assembly of claim 4 wherein the mover component and the stator component cooperate to form a first chamber within the stator body on one side of the piston disc, and a second chamber within the stator body on the opposite side of the piston disc; wherein the actuator includes a fluid source that is in fluid communication with the first chamber via a first transfer port and that is in fluid communication with the second chamber via a second transfer port; and wherein the actuator selectively directs fluid from the fluid source into and out of the first chamber and the second chamber via the first transfer port and the second transfer port, respectively, to selectively control a pressure in each of the first chamber and the second chamber.

6. The actuator assembly of claim 1 wherein the actuator moves the mover component relative to the stator component along the mover axis; and wherein the signal processor is electrically connected to the actuator to position the mover component and the device relative to the stator component based at least in part on the sensor signals.

7. The actuator assembly of claim 1 further comprising a calibration measurement system that generates a mapping signal as the mover component is moved along the mover axis; and wherein the signal processor is configured to map a position of each of the plurality of sensors based at least in part on the sensor signals and the mapping signal.

8. The actuator assembly of claim 1 wherein the signal processor uses a look-up table and the sensor signals to estimate the position of the mover component.

9. The actuator assembly of claim 1 wherein the signal processor uses a curve-fitting method to estimate the position of the mover component from the sensor signals.

10. The actuator assembly of claim 1 wherein the signal processor uses a triangle curve-fitting method to estimate the position of the mover component from the sensor signals.

11. The actuator assembly of claim 1 wherein the magnet assembly includes a permanent magnet that is surrounded by the magnetic field; wherein the magnet assembly has a magnet axis that is substantially parallel to the mover axis; and wherein the permanent magnet has a perpendicular orientation relative to the magnet axis.

12. The actuator assembly of claim 1 wherein the magnet assembly includes a permanent magnet that is surrounded by the magnetic field; wherein the magnet assembly has a magnet axis that is substantially parallel to the mover axis; and wherein the permanent magnet has an axial orientation relative to the magnet axis.

13. The actuator assembly of claim 1 wherein the signal processor estimates the position of the mover component along the mover axis at the given point in time based only on the sensor signals from the at least two of the sensors that are positioned within the active region of the magnetic field at the given point in time.

14. A method for moving a device, the method comprising the steps of:

providing a stator component;

coupling a mover component to the device;

moving the mover component relative to the stator component along a mover axis with an actuator so that the device moves relative to the stator component as the mover component is moved relative to the stator component along the mover axis;

coupling a magnet assembly to the mover component, the magnet assembly producing a consistent magnetic field that moves relative to the stator component as the mover component moves relative to the stator component;

positioning a plurality of spaced apart sensors in a fixed position relative to the stator component, the sensors being positioned along a path of the mover component such that at least two of the sensors are positioned within an active region of the magnetic field at all times as the mover component moves relative to the stator component along the mover axis, the sensors being configured to sense changes in the magnetic field produced by the magnet assembly as the mover component moves along the mover axis, each sensor being a transducer that generates a sensor signal that varies its output voltage in response to the changing magnetic field from the magnet assembly as the mover component is moved relative to the sensors;

receiving the sensor signals with a signal processor; and

estimating a position of the mover component along the mover axis at a given point in time with the signal processor based at least in part on the sensor signals from the at least two of the sensors that are positioned within the active region of the magnetic field at the given point in time; and

wherein the actuator moves the mover component and the magnet assembly relative to the stator component while the magnet assembly is being used for monitoring movement of the mover component relative to the stator component.

15. The method of claim 14 wherein the step of positioning includes the plurality of sensors being aligned and spaced apart along a sensor axis that is substantially parallel to the mover axis.

16. The method of claim 14 further comprising the steps of electrically connecting the signal processor to the actuator, and positioning the mover component and the device relative to the stator component with the signal processor based at least in part on the sensor signals.

17. The method of claim 14 wherein the step of estimating includes estimating a position of the mover component along the mover axis with the signal processor using a look-up table and the sensor signals.

18. The method of claim 14 wherein the step of estimating includes estimating a position of the mover component along the mover axis with the signal processor based on the sensor signals using a curve-fitting method.

19. The method of claim 14 wherein the step of coupling a magnet assembly includes the magnet assembly including a permanent magnet that is surrounded by the magnetic field; the magnet assembly having a magnet axis that is substantially parallel to the mover axis; and the permanent magnet having a perpendicular orientation relative to the magnet axis.

20. The method of claim 14 wherein the step of coupling a magnet assembly includes the magnet assembly including a permanent magnet that is surrounded by the magnetic field; the magnet assembly having a magnet axis that is substantially parallel to the mover axis; and the permanent magnet having an axial orientation relative to the magnet axis.