Detecting loading and unloading of material

• US 8,188,863 B2
• Filed: 11/26/2008
• Issued: 05/29/2012
• Est. Priority Date: 11/26/2008
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Rinkes, Charles, Durham, Raymond, Lawrence, Loren, Roberts, Guy
• Primary Examiner(s): Lau, Hoi
• Application Number:
  US12/323,656
• Publication Number:
  US 20100127870A1
• Time in Patent Office: 1,280 Days
• Field of Search: 340/572.1, 340/539.13, 340/5.92, 340/10.3, 340/539.23, 340/539.22, 705/14.24, 705/22, 705/28, 235/385, 700/236
• US Class Current: 340/572.1
• CPC Class Codes: B66F 9/0755 Position control; Position detectors

Abstract

An apparatus and techniques for detecting the loading and unloading of materials on a mobile structure are disclosed. The techniques can be used to detect when material is on a support structure of the mobile structure and to detect when the material is off the support structure of the mobile structure.

Claims

1. A method for determining whether an object is positioned on or off a support structure of a mobile structure, the method comprising:

comparing a current distance value to a prior distance value and a N number of pre-programmed distance measurements, said prior distance value is a distance measurement from the mobile structure to the object at a first time period, said current distance value a distant measurement from the mobile structure to the object at a second time period, said second time period subsequent to said first time period, N being an integer value greater than 1;

setting a value of a direction variable to represent a movement of the mobile structure in a forward or reverse direction based on the comparison of the current distance value to the prior distance value;

setting a plurality of trip point values to represent movement of the mobile structure over the N number of pre-programmed distance measurements based on the comparison of the current distance value with the N number of pre-programmed distance measurements;

determining an on-off condition for the object based on the direction variable and the plurality of trip point values set.

2. The method of claim 1, comprising:

comparing the current distance value to a first noise threshold value, the first noise threshold value being a distance measurement; and

determining the on-off condition based on the direction variable, the plurality of set trip points, and the comparison of the current distance value to the first nose threshold value.

3. The method of claim 2, comprising incrementing a value of a noise counter variable if the current distance value exceeds said first nose threshold value.

4. The method of claim 3, comprising:

comparing the value of the noise counter variable to a second noise threshold value, the second noise threshold value being a numeric integer value; and

setting the plurality of trip point values and the direction variable to indicate non-movement of the mobile structure based on the comparison of the value of the noise counter variable to the second noise threshold value.

5. The method of claim 4, comprising setting the on-off condition to an OFF value if the value of the direction variable represents the reverse direction and the plurality of trip point values indicate the movement of the mobile structure, the OFF value representing the object positioned off the support structure.

6. The method of claim 5, comprising:

incrementing a value of a reverse counter variable if the current distance value exceeds the prior distance value;

comparing the value of the reverse counter variable to a reverse threshold value, the reverse threshold value being a numeric count value; and

setting the direction variable to indicate the REVERSE direction of the mobile structure based on the comparison of the value of the reverse counter variable to the reverse threshold value.

7. The method of claim 6, comprising comparing the current distance value to the prior distance value if the current distance value exceeds a pre-determined minimum distance to detect an OFF condition of the mobile structure.

8. The method of claim 4, comprising setting the on-off condition to an ON value if the value of the direction variable represents the forward direction and the plurality of trip point values indicate the movement of the mobile structure, the ON value representing the object positioned on the support structure.

9. The method of claim 5, comprising:

incrementing a value of a forward counter variable if the current distance value is less than the prior distance value;

comparing the value of the forward counter variable to a forward threshold value, the forward threshold value being a numeric count value; and

setting the direction variable to indicate the FORWARD direction of the mobile structure based on the comparison of the value of the forward counter variable to the forward threshold value.

10. The method of claim 6, comprising comparing the current distance value to the prior distance value if the current distance value is less than a length of the support structure.

11. The method of claim 1, comprising coupling operatively a proximity sensor to the mobile structure to determine the current distance and prior distance values.

12. The method of claim 1, comprising at least one of activating and deactivating an RFID reader to communicate with an RFID tag associated with the object based on the on-off condition.

13. A RFID reader operatively coupled to a mobile structure, the RFID reader configured to determine whether an object associated with an RFID tag is positioned on or off a support structure of the mobile structure, the RFID reader including a processor and memory configured to include memory storing instructions that, in response to a request, cause the processor to:

compare a current distance value to a prior distance value and a N number of pre-programmed distance measurements, said prior distance value is a distance measurement from the mobile structure to the object at a first time period, said current distance value a distant measurement from the mobile structure to the object at a second time period, said second time period subsequent to said first time period, N being an integer value greater than 1;

set a value of a direction variable to represent a movement of the mobile structure in a forward or reverse direction based on the comparison of the current distance value to the prior distance value;

set a plurality of trip point values to represent movement of the mobile structure over the N number of pre-programmed distance measurements based on the comparison of the current distance value with the N number of pre-programmed distance measurements; and

determine an on-off condition for the object based on the direction variable and the plurality of trip point values set.

14. The RFID reader of claim 13, wherein the memory stores instructions that, in response to receiving the request, cause the processor to:

compare the current distance value to a first noise threshold value, the first noise threshold value being a distance measurement; and

determine the on-off condition based on the direction variable, the plurality of set trip points, and the comparison of the current distance value to the first nose threshold value.

15. The RFID reader of claim 14, wherein the memory stores instructions that, in response to receiving the request, cause the processor to increment a value of a noise counter variable if the current distance value exceeds said first nose threshold value.

16. The RFID reader of claim 15, wherein the memory stores instructions that, in response to receiving the request, cause the processor to:

compare the value of the noise counter variable to a second noise threshold value, the second noise threshold value being a numeric integer value; and

set the plurality of trip point values and the direction variable to indicate non-movement of the mobile structure based on the comparison of the value of the noise counter variable to the second noise threshold value.

17. The RFID reader of claim 16, wherein the memory stores instructions that, in response to receiving the request, cause the processor to set the on-off condition to an OFF value if the value of the direction variable represents the reverse direction and the plurality of trip point values indicate the movement of the mobile structure, the OFF value representing the object positioned off the support structure.

18. The RFID reader of claim 17, wherein the memory stores instructions that, in response to receiving the request, cause the processor to:

increment a value of a reverse counter variable if the current distance value exceeds the prior distance value;

compare the value of the reverse counter variable to a reverse threshold value, the reverse threshold value being a numeric count value; and

set the direction variable to indicate the REVERSE direction of the mobile structure based on the comparison of the value of the reverse counter variable to the reverse threshold value.

19. The RFID reader of claim 18, wherein the memory stores instructions that, in response to receiving the request, cause the processor to compare the current distance value to the prior distance value if the current distance value exceeds a length of the support structure.

20. The RFID reader of claim 16, wherein the memory stores instructions that, in response to receiving the request, cause the processor to set the on-off condition to an ON value if the value of the direction variable represents the forward direction and the plurality of trip point values indicate the movement of the mobile structure, the ON value representing the object positioned on the support structure.

21. The RFID reader of claim 17, wherein the memory stores instructions that, in response to receiving the request, cause the processor to comprising:

increment a value of a forward counter variable if the current distance value is less than the prior distance value;

compare the value of the forward counter variable to a forward threshold value, the forward threshold value being a numeric count value; and

set the direction variable to indicate the FORWARD direction of the mobile structure based on the comparison of the value of the forward counter variable to the forward threshold value.

22. The RFID reader of claim 18, wherein the memory stores instructions that, in response to receiving the request, cause the processor to compare the current distance value to the prior distance value if the current distance value is less than a length of the support structure.

23. The RFID reader of claim 13, wherein a proximity sensor is at least one of operatively coupled to the RFID reader and included in the RFID reader for determining the current distance and prior distance values.

24. The RFID reader of claim 13, wherein the RFID reader is at least one of activated and deactivated to communicate with the RFID tag based on the on-off condition.

25. The RFID reader of claim 13, wherein the mobile structure is at least one of a forklift, pallet jack, hand truck, and conveyor.