Adaptive ejector valve array
A method for providing adaptive control of the flow of a plurality of ejector valves arranged in close proximity to each other in a sorting machine is described. The method comprises measuring a temporal response curve for each ejector valve, comparing the measured temporal response curve for each ejector valve to a library set of previously stored temporal response curves, determining from the comparison a predicted flow for each ejector valve, and adapting a drive signal for each ejector valve in dependence on the predicted flow. Temporal response curves may be measured and compared in a calibration (non-sorting) mode, and real-time feedback of the measured temporal responses in a sorting mode may be used to indicate health of a valve and to further adapt the drive signal to provide conformal performance. The number of neighboring ejector valves may also be taken into account.
1. A method for providing adaptive control of the flow of a plurality of ejector valves arranged in an array in a sorting machine, the method comprising the steps of:
measuring a temporal response curve for each ejector valve;
comparing the measured temporal response curve for each ejector valve to a library set of previously stored temporal response curves, wherein the set of stored temporal response curves in the library is associated with the number of neighbouring ejector valves each ejector valve has in the array;
determining from the comparison a predicted flow for each ejector valve; and
adapting a drive signal for each ejector valve in dependence on the predicted flow.
2. A method for providing adaptive control of the flow of a plurality of ejector valves arranged in an array in a sorting machine, the method comprising the steps of:
measuring a temporal response curve for each ejector valve;
comparing the measured temporal response curve for each ejector valve to a library set of previously stored temporal response curves, wherein the step of measuring a temporal response curve for each ejector valve comprises measuring a temporal response curve for each operation of the ejector valve over a number of operations of that ejector valve, and averaging the obtained response curves for each operation to produce the measured temporal response curve;
determining from the comparison a predicted flow for each ejector valve; and
adapting a drive signal for each ejector valve in dependence on the predicted flow.
3. The method according to claim 2 , wherein the set of stored temporal response curves in the library is associated with a flow parameter.
4. The method according to claim 3 , wherein the flow parameter is associated with at least one electrical parameter.
5. The method according to claim 4 , wherein the electrical parameter is (i) current associated with the ejector valve, (ii) rate of change of current associated with the ejector valve, (iii) flux or flux linkage associated with the ejector valve, or (iv) voltage associated with the ejector valve.
6. The method according to claim 2 , wherein the step of adapting the drive signal comprises adjusting a time delay before the drive signal is applied and/or the length of a portion of the drive signal.
7. The method according to claim 2 , wherein the step of adapting the drive signal comprises adjusting the applied voltage of the drive signal.
8. The method according to claim 2 , wherein the step of adapting the drive signal comprises adjusting the height and/or length of a peak at the beginning of the drive signal.
9. The method according to claim 2 , wherein the step of adapting the drive signal comprises adjusting the height and/or length of a hold period of the drive signal.
10. The method according to claim 2 , wherein the step of adapting the drive signal comprises adjusting a rate of decay at the end of the drive signal.
11. The method according to claim 2 , wherein the step of adapting the drive signal comprises adjusting the depth and/or length of a trough at the end of the drive signal.
12. The method according to claim 2 , wherein, a dynamic temporal response curve of an ejector valve is measured during a sorting operation to determine a flow which is compared with the previously predicted flow to provide an indication of the health or condition of the ejector valve.
13. The method according to claim 12 , wherein the indication of the health or condition of the ejector valve is used to further adapt the previously determined drive signal.
14. The method according to claim 13 , wherein the indication of the health or condition of the ejector valve is associated with the ejector valve opening time, and the further adaptation of the drive signal comprises applying the deviation in time between the measured ejector valve opening time and a previously predicted flow represented by an associated ejector valve opening time.
15. The method according to claim 2 , wherein the previously predicted flow is updated by the currently determined flow and timing of each ejector valve.
16. A method for providing adaptive control of the flow of a plurality of ejector valves arranged in an array in a sorting machine, the method comprising the steps of:
measuring a temporal response curve for each ejector valve;
comparing the measured temporal response curve for each ejector valve to a library set of previously stored temporal response curves;
determining from the comparison a predicted flow for each ejector valve, wherein the predicted flow for each ejector valve is determined by computing the cumulative error between the mean temporal response curve of the library set and the measured temporal response curve of the ejector valve, and selecting from the library set those temporal response curves which minimise error with respect to the measured temporal response curve to predict the flow; and
adapting a drive signal for each ejector valve in dependence on the predicted flow.
17. The method according to claim 16 , wherein the predicted flow is further determined by weighting the predicted flow of each of the selected library curves with respect to their respective error.
18. A method for providing adaptive control of the flow of a plurality of ejector valves arranged in an array in a sorting machine, the method comprising the steps of:
measuring a temporal response curve for each ejector valve;
comparing the measured temporal response curve for each ejector valve to a library set of previously stored temporal response curves, wherein the set of stored temporal response curves in the library is associated with temperature, and the ambient temperature of an enclosure housing the ejector valves is measured and used in the selection of library curves;
determining from the comparison a predicted flow for each ejector valve; and
adapting a drive signal for each ejector valve in dependence on the predicted flow.
19. A sorting apparatus comprising a plurality of ejector valves arranged in an array, and having at least one processing and control module adapted to perform the method of claim 2 .