Method and device to discriminate two ends of an article from each other

Abstract

The method comprises the steps of: generating a curve (PF) which approximates the profile of one end (P) of an article; processing said curve to determine whether it approximates the profile of said first or said second end.

1 . A method for distinguishing from each other a first end and a second end of an elongated article, said first end and said second end having profiles differing from each other, the method comprising the steps of:
 generating at least one curve which approximates the profile of at least one of said ends;   processing said curve to determine whether said curve approximates the profile of said first end or of said second end.   
   
   
       2 . A method as claimed in  claim 1 , further comprising the steps of:
 moving with respect to each other an article and an array of photocells;   gradually intercepting beams of the photocells with the end of the article;   determining a plurality of points which lie on a profile that approximates the end of the article based on relative positions taken by the article and the photocells and electrical signals generated by gradual interception of the optical beams of the photocells.   
   
   
       3 . A method as claimed in  claim 1 , further comprising the steps of:
 arranging a plurality of photocells according to a predetermined arrangement;   moving said arrangement of photocells and said article with respect to each other along a direction of relative movement, so that one end of said article intercepts the beams of said photocells during the relative movement;   determining the coordinates of a plurality of points belonging to the profile of said end of the article that intercepts said beams, on the basis of: the relative positions taken by said article with respect to said photocells during the reciprocal movement, and of the arrangement of the photocells.   
   
   
       4 . A method as claimed in  claim 2 , wherein each time a photocell is intercepted by said article during said relative movement, the relative position between article and photocells is detected, the position of the intercepted photocell and the reciprocal position, along said direction of relative movement, between photocells and article defining the coordinates of a point belonging to said profile. 
   
   
       5 . A method as claimed in  claim 1 , further comprising the step of generating said curve that approximates the profile of said end of the article interpolating at least some of said points belonging to the profile of said end. 
   
   
       6 . A method as claimed in  claim 5 , wherein said points are interpolated with linear segments. 
   
   
       7 . A method as claimed in  claim 5 , wherein at least of the two end points identified on said profile are discarded. 
   
   
       8 . A method as claimed in  claim 1 , wherein said curve is processed to determine the trend of the slope thereof, the first end and the second end of said article being distinguished from each other as a function of said trend of the slope. 
   
   
       9 . A method as claimed in  claim 1 , wherein said curve is reproduced in a system of coordinates with an axis on which the end points of the curve lie. 
   
   
       10 . A method as claimed in  claim 1 , wherein a difference between a maximum value and a minimum value of a coordinate of said curve is determined in a reference system, said difference forming a parameter to distinguish said first end from said second end. 
   
   
       11 . A method as claimed in  claim 10 , wherein said difference is compared with a predetermined value; the end being recognized according to whether said difference is greater or less than said predetermined value. 
   
   
       12 . A method as claimed in  claim 10 , further comprising the steps of:
 determining the coordinates of two points spaced from each other of said curve in a first reference system;   identifying a straight line joining said two points;   taking said straight joining line as one of the coordinates of a second reference system rotated with respect to the first reference system;   determining said difference in said second reference system.   
   
   
       13 . A method as claimed in  claim 12 , wherein said first and said second reference systems are Cartesian reference systems, and wherein said difference is represented by the difference between the maximum value and the minimum value of the coordinate of the points of said curve along a reference axis orthogonal to said straight joining line. 
   
   
       14 . A method as claimed in  claim 1 , wherein a derivative of said curve is calculated. 
   
   
       15 . A method as claimed in  claim 14 , wherein maximum and minimum values of said derivative are determined. 
   
   
       16 . A method as claimed in  claim 15 , wherein the difference between said maximum and minimum values of the derivative are determined and said first and second ends are discriminated on the basis of a comparison between said difference and a threshold value. 
   
   
       17 . A method as claimed in  claim 1 , wherein said article is moved along a path and taken with one of the ends thereof to intercept beams of photocells disposed in a fixed position. 
   
   
       18 . A method as claimed in  claim 1 , wherein said article is made to advance with respect to said photocells by a predetermined degree, irrespective of the number of photocells intercepted. 
   
   
       19 . A method as claimed in  claim 1 , further comprising the step of:
 determining total number of photocells intercepted by the article after the article has performed a predetermined movement subsequent to interception of the first photocell; and   comparing said total number with a predetermined minimum number, wherein a first data is obtained from said comparison to discriminate said first end from said second end of the article.   
   
   
       20 . A method as claimed in  claim 1 , wherein said article is one of a stocking and a sock. 
   
   
       21 . A method as claimed in  claim 20 , wherein said first end is an elastic band end and said second end is a toe of said sock. 
   
   
       22 . A method according to  claim 1 , wherein both ends of an article of manufacture are detected and two curves approximating the profiles of both said ends are generated; and wherein both said curves are processed to determine whether they approximate the profile of said first or said second end. 
   
   
       23 . A device for distinguishing from each other a first end and a second end of an article, the device comprising;
 an arrangement of sensors to identify a plurality of points belonging to a profile of at least one end of said article; and   a control and processing unit which, as a function of the coordinates of said points, detects whether said plurality of points belong to said first end or to said second end.   
   
   
       24 . A device as claimed in  claim 23 , wherein said control and processing unit is programmed so as to generate a curve that approximates the profile of said end as a function of said points identified by said sensors. 
   
   
       25 . A device as claimed in  claim 23 , wherein said sensors comprise an arrangement of photocells, and wherein handling members are provided to move with respect to each other, along a direction of relative movement, said article and said arrangement of photocells, a system being provided to detect the reciprocal position between said article and said photocells. 
   
   
       26 . A device as claimed in  claim 25 , wherein said control and processing unit is programmed to determine said plurality of points associating the positions of the photocells that are intercepted by said article, during the relative movement between the article and the photocells, with the position taken time by time by the article with respect to the photocells along said direction of relative movement. 
   
   
       27 . A device as claimed in  claim 25 , wherein said arrangement of photocells comprises a linear string of photocells. 
   
   
       28 . A device as claimed in  claim 27 , wherein said string of photocells is disposed according to an alignment orthogonal to said direction of relative movement. 
   
   
       29 . A device as claimed in  claim 23 , wherein said control and processing unit is programmed so that each time a photocell is intercepted by said article during said relative movement, the relative position between article and photocells is detected, the position of the photocell intercepted and the reciprocal position, along said direction of relative movement, between article and photocells defining the coordinates of a point belonging to said profile. 
   
   
       30 . A device as claimed in  claim 23 , wherein said control and processing unit is programmed to approximate the profile of said end of the article interpolating at least some of said points belonging to said profile. 
   
   
       31 . A device as claimed in  claim 30 , wherein said control and processing unit is programmed to interpolate said points through linear segments. 
   
   
       32 . A device as claimed in  claim 30 , wherein said control and processing unit is programmed to discard the first and the last of said points. 
   
   
       33 . A device as claimed in  claim 23 , wherein said control and processing unit is programmed to determine the trend of the slope of the curve generated through said points identified by said sensors, the first end and the second end of said article being distinguished from each other as a function of said trend. 
   
   
       34 . A device as claimed in  claim 23 , wherein said control and processing unit is programmed to identify a straight line passing through two end points of said curve, and to reproduce the coordinates of said points in a reference system, a coordinate of which is parallel to said straight line. 
   
   
       35 . A device as claimed in  claim 23 , wherein said control and processing unit is programmed to determine a difference between a maximum value and a minimum value of a coordinate of said curve in a reference system, and to distinguish the first end from the second end on the basis of said difference. 
   
   
       36 . A device as claimed in  claim 35 , wherein said control and processing unit is programmed to compare said difference with a predetermined value; and to distinguish the end according to whether said difference is greater or less than said predetermined value. 
   
   
       37 . A device as claimed in  claim 35 , wherein said control and processing unit is programmed to perform the steps of:
 determining the coordinates of two points spaced from each other of said curve in a first reference system;   identifying a straight line joining said two points;   taking said straight joining line as one of the coordinates of a second reference system rotated with respect to the first reference system;   determining said difference in said second reference system.   
   
   
       38 . A device as claimed in  claim 37 , wherein said first and said second reference systems are Cartesian reference systems, and wherein said difference is represented by the difference between the maximum value and the minimum value of the coordinate of the points of said curve along an axis of reference orthogonal to said straight joining line. 
   
   
       39 . A device as claimed in  claim 33 , wherein said control and processing unit is programmed to calculate the derivative of said curve. 
   
   
       40 . A device as claimed in  claim 34 , wherein said control and processing unit is programmed for the minimum and maximum values of said derivative. 
   
   
       41 . A device as claimed in  claim 40 , wherein said control and processing unit is programmed to determine the difference between said maximum and minimum values of the derivative and to check the difference with a threshold value. 
   
   
       42 . A device as claimed in  claim 23 , wherein said control and processing unit is programmed to perform a first discrimination between the first end and the second end on the basis of the total number of photocells intercepted by said article after said article has performed, with respect to said photocells, a relative movement of a predetermined degree starting from the interception position of the first photocell. 
   
   
       43 . A device as claimed in  claim 23 , wherein said sensors are disposed in fixed position and handling members cause translation of the articles along a direction of movement towards said sensors. 
   
   
       44 . A device as claimed in  claim 23 , including further comprising handling members to move said article with respect to said sensors such that both ends of said articles are passed in front of said sensors. 
   
   
       45 . A method as claimed in  claim 2 , comprising the steps of:
 arranging a plurality of photocells according to a predetermined arrangement;   moving said arrangement of photocells and said article with respect to each other along a direction of relative movement, so that one end of said article intercepts the beams of said photocells during the relative movement;   determining the coordinates of a plurality of points belonging to the profile of said end of the article that intercepts said beams, on the basis of: the relative positions taken by said article with respect to said photocells during the reciprocal movement, and of the arrangement of the photocells.   
   
   
       46 . A method as claimed in  claim 3 , wherein each time a photocell is intercepted by said article during said relative movement, the relative position between article and photocells is detected, the position of the intercepted photocell and the reciprocal position, along said direction of relative movement, between photocells and article defining the coordinates of a point belonging to said profile. 
   
   
       47 . A device as claimed in  claim 24 , wherein said sensors comprise an arrangement of photocells, and wherein handling members are provided to move with respect to each other, along a direction of relative movement, said article and said arrangement of photocells, a system being provided to detect the reciprocal position between said article and said photocells. 
   
   
       48 . A device as claimed in  claim 47 , wherein said control and processing unit is programmed to determine said plurality of points associating the positions of the photocells that are intercepted by said article, during the relative movement between the article and the photocells, with the position taken time by time by the article with respect to the photocells along said direction of relative movement. 
   
   
       49 . A device as claimed in  claim 25 , wherein said arrangement of photocells comprises a linear string of photocells.