Noncontacting position indicating system

• US 20020077752A1
• Filed: 03/16/2001
• Published: 06/20/2002
• Est. Priority Date: 09/28/2000
• Status: Active Grant

• Current Assignee: Eldec Corporation (Crane Company)
• Original Assignee: Eldec Corporation (Crane Company)
• Inventors: Lamping, Jeff, Burreson, Bernard, Orr, Alan, Knappert, Patrick A., Woolsey, Kevin G.
• Granted Patent: US 6,690,159 B2
• Time in Patent Office: Days
• US Class Current: 701/300
• CPC Class Codes: A61B 2090/0811 for the position of a particular part of an instrument with respect to the rest of the instrument, e.g. position of the anvil of a stapling instrument
• CPC Class Codes: G01D 5/251 one conductor or channel

Abstract

A target device is carried by or mounted on a first part movable relative to a second part. The second part has a sensing device including an array of sensors providing outputs responsive to the magnet field of the target device. A processing device receives the outputs of the sensors and calculates relative positions of the two parts based on the outputs.

Claims

1. A position indicating system comprising:

a first part having a target device producing a magnetic field;

a second part having a sensing device including an array of sensors producing respective outputs that vary as a function of magnetic field strength, the first part being movable relative to the second part with the target device adjacent to the sensing device; and

a processing device receiving the outputs of the sensors for calculating the relative positions of the first and second parts based on the outputs of several of the sensors.

2. The system defined in claim 1, in which the first and second parts are movable linearly relative to each other, the direction of relative movement of the first and second parts defining a sensing direction, and the array of sensors of the sensing device being elongated in the sensing direction.

3. The system defined in claim 2, in which the sensors of the array are spaced known distances from each other in the sensing direction.

4. The system defined in claim 2, in which the sensors of the array are spaced uniformly in the sensing direction.

5. The system defined in claim 3, in which the sensors are arranged in a plurality of rows extending lengthwise of the sensing direction.

6. The system defined in claim 4, in which the sensors of each row are spaced uniformly, and the sensors of adjacent rows are staggered relative to each other.

7. The system defined in claim 1, in which the processing device includes a processor programmed to scan the outputs of the sensors, determine the sensor having the output indicating the greatest magnetic field strength, and determining the relative positions of the first and second parts based on the outputs of a predetermined number of sensors at each side of the sensor having the output indicating the greatest magnetic field strength.

8. The system defined in claim 1, including an enclosure enclosing the first part, the sensing device being mounted outside of the enclosure.

9. The system defined in claim 1, in which the first part is elongated and has a plurality of target devices spaced lengthwise thereof.

10. The system defined in claim 9, in which the array of sensors of the sensing device is elongated, the target devices of the first part being spaced apart a distance less than the length of the elongated array of sensors of the sensing device.

11. The system defined in claim 10, in which the target devices of the first part are spaced irregularly along the length of the first part, and the target devices having north-south orientations such that the distance and orientation difference between any two adjacent target devices is unique along the length of the first part.

12. The system defined in claim 1, in which the first part and the second part are movable nonlinearly relative to each other.

13. The system defined in claim 12, in which the first and second parts are rotatable relative to each other.

14. The system defined in claim 13, in which the sensors of the sensing device are arranged in a circular array.

15. The system defined in claim 12, in which the target device includes a plurality of magnets having different respective north-south orientations.

16. The system defined in claim 1, in which the sensors of the sensing device are arranged in a two-dimensional array.

17. The system defined in claim 1, in which the processing device receives the outputs of the sensors and calculates the location of the first part relative to the second part in one dimension.

18. The system defined in claim 1, in which the processing device receives the outputs of the sensors and calculates the location of the first part relative to the second part in two dimensions.

19. The system defined in claim 1, in which the processing device receives the outputs of the sensors and calculates the location of the first part relative to the second part in three dimensions.

20. The system defined in claim 1, in which the processing device receives the outputs of the sensors and calculates relative attitude of the first part and the second part in at least one of pitch, yaw and roll.

21. The system defined in claim 1, in which the processing device receives the outputs of the sensors and calculates the location of the first part relative to the second part in at least one dimension and also relative attitude in at least one of pitch, yaw and roll.

22. A method for determining the position of a first part relative to a second part which comprises:

providing the first part with a target device producing a magnetic field;

providing the second part with a sensing device including an array of sensors producing respective outputs that vary as a function of magnetic field strength, the first part being movable relative to the second part with the target device adjacent to the sensing device; and

processing the outputs of the sensors to calculate relative positions of the first and second parts based on the outputs of several of the sensors.

23. The system defined in claim 22, in which the relative positions are selected from the group consisting of relative location in at least one dimension, relative yaw, relative pitch, and relative roll.

24. The method defined in claim 22, including determining which of the sensors has the output indicating the greatest magnetic field strength, and limiting the processing to such sensor and a predetermined number of sensors adjacent to such sensor.

25. The method defined in claim 22, in which the sensors provide outputs proportional to magnetic field strength, and including processing the outputs of several of the sensors by calculating the mean output for selected sensors.

26. The method defined in claim 22, including measuring the offset for all sensors, storing the offset values and using the offset values when processing the outputs to determine the relative positions of the first and second parts.

27. The method defined in claim 22, including adjusting the outputs of selected sensors based on stored gain values.

28. The method defined in claim 22, including processing the outputs of the sensors by determining a nonlinear function fit for the outputs of selected sensors.

29. The method defined in claim 22, including performing a calibration sequence and error correction analysis for use in the processing of the outputs of the several sensors to determine relative positions of the first and second parts.

30. The method defined in claim 22, including processing the outputs of the sensors at different times and calculating change in relative positions of the first and second parts to determine at least one of speed and acceleration of movement of one of the parts relative to the other part.