Method and means for backspacing a line follower in a digitizing system

Claim 1

In a digitizing system the combination comprising means for supporting a workpiece on which a line to be digitized appears, a line-sensing device supported for movement relative to said supporting means so as to be movable along any line on a workpiece supported thereby, drive means for driving said sensing device relative to said supporting means, line following control means responsive to output signals from said sensing device for energizing said drive means to cause said sensing device to be driven along the line sensed thereby, encoding means connected with said sensing device for producing a coded representation of the instantaneous position of said sensing device relative to a workpiece supported on said supporting means, means operable when said drive means are energized by said line-following control means for periodically sampling said encoder means as said sensing device is driven along a line to obtain coded representations of points spaced along said line, a data storage means connected with said sampling means for storing in succession a given number of said sampled coded representations, said data storage means being operable to accept said given number of sampled coded representations and to thereafter output the oldest coded representation stored therein as each new coded representation is received, a plotting control means responsive to a coded representation extracted from said storage means for energizing said drive means to drive said sensing device to the point represented by said extracted coded representation, means under the control of an operator for selectively enabling and disabling said line-following control means, and extracting means operable when said line-following control means is disabled to extract one at a time and in the order of the newest one first at least one coded representation from said data storage means and to transmit such extracted representation to said plotting control means for use thereby.

Claim 9

The method for operating an automatic line follower in a digitizing system which method comprises the steps of: conditioning an automatic line follower having a line-sensing device to automatically follow a line on a given workpiece, periodically sampling encoders connected with the line-sensing device of the line follower to derive coded representations of points spaced along the line being followed, storing in succession a given number of the most recent ones of said coded representations, after said given number of coded representations have been stored storing each new sampled coded representation and as a new sampled coded representation is so stored removing from storage and outputting the oldest stored coded representation, observing the progress of said line-sensing device, continuing the aforementioned steps until it is observed that the sensing device has departed from the line to be followed, thereafter disabling said line follower from automatically following a line on said given workpiece, extracting one at a time the newest coded representations from storage in the order of the newest one first and supplying each such extracted coded representation to a means operable to drive said line-sensing device in a backspacing manner to the point represented by such coded representation, continuing said one at a time extraction of said newest coded representations and the accompanying point to point backspacing of said sensing device until said sensing device is returned to a point on the line to be followed, and thereafter again conditioning said line follower to automatically follow said line.

Claim 10

The method for operating an automatic line follower in a digitizing system which method comprises the steps of: conditioning an automatic line follower having a line-sensing device to automatically follow a line on a given workpiece, periodically sampling encoders connected with the line-sensing device of the line follower to derive coded representations of points spaced along the line being followed, storing in succession a given number of the most recent ones of said coded representations, after said given number of coded representations have been stored storing each new sampled coded representation and as a new sampled coded representation is so stored removing from storage and outputting the oldest stored coded representation, observing the progress of said line-sensing device, continuing the aforementioned steps until it is observed that the sensing device has departed from the line to be followed, thereafter disabling said line follower from automatically following a line on said given workpiece, extracting one at a time the newest coded representations from storage in the order of the newest one first and supplying each such extracted coded representation to a means operable to drive said line-sensing device in a backspacing manner to the point represented by such coded representation, continuing said one at a time extraction of said newest coded representations and the accompanying point to point backspacing of said sensing device until said sensing device is returned to a point on the line to be followed, and thereafter again conditioning said line follower to automatically follow said line.