Handwriting apparatus for information collection based on force and position

• US 5,022,086 A
• Filed: 12/20/1988
• Issued: 06/04/1991
• Est. Priority Date: 12/20/1988
• Status: Expired due to Fees

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Crane, Hewitt D., Hammon, Robert W.
• Primary Examiner(s): Razavi, Michael
• Application Number:
  US07/287,440
• Time in Patent Office: 896 Days
• Field of Search: 382/3, 382/13, 382/17, 382/59, 382/2
• US Class Current: 382/121
• CPC Class Codes: G06V 10/12 Details of acquisition arrangements; Constructional details thereof
• CPC Class Codes: G06V 40/30 Writer recognition; Reading and verifying signatures
• CPC Class Codes: G07C 9/35 by means of a handwritten signature

Abstract

An apparatus for collecting information directly at a point on a surface comprises the combination of a stylus with means for sensing force along at least one axis in a surface at a point on the surface and a position sensing platen or pad with means for sensing a true position along at least one axis on the surface at the point in question. Collected information is processed to obtain figures of merit. Features extraction or rubbery correlation in five dimensions may be employed to obtain suitable figures of merit for objective evaluation.

Claims

1. An apparatus for gathering and collecting handwritten information based upon force and position of a writing instrument comprising in combination:

a tablet means for sensing a first position component along a first axis in a Cartesian coordinate system and for sensing a second position component along a second axis in said Cartesian coordinate system transverse to said first axis;

force sensing means within said writing instrument for sensing force generated by the writing instrument about a point at the intersection of said first axis and said second axis, said force being expressible in third, fourth and fifth spatial axes related to orientation of said writing instrument, said force sensing means including;

means for sensing a first force component in said third axis,

means for sensing a second force component in said fourth axis transverse to said third axis, and

means for sensing a third force component in said fifth axis transverse to said third axis and said fourth axis;

means for logging, with respect to time, said first position component, said second position component, said first force component, said second force component and said third force component to produce logged position and force information; and

means responsive to said logged position and force information for combining said logged position and force information to produce output information.

2. The apparatus according to claim 1, wherein said combining means comprises a features log for receiving said logged position and force information, means for generating a features template, said features template comprising a collection of logged features of said features log and an identification with a specific norm, means for storing said features template and means coupled to said features log and to said features template storing means for comparing said features template with said features log to produce a figure of merit.

3. The apparatus according to claim 1, wherein a template set for said features template storing means comprises mean values and standard deviation values for each time segment of said position information and force information with logged samples and means for correlating said template set with logged samples to produce a figure of merit for each of said positions and forces.

4. The apparatus according to claim 3, further including means for combining said position and force figures of merit into a single value for comparison with a standard.

5. A method for gathering and collecting information based upon force and position of a stylus point of a writing instrument, said method comprising the steps of:

(a) sensing a first position component of a stylus point along a first axis in a Cartesian coordinate system with respect to time;

(b) sensing a second position component of said stylus point along a second axis in said Cartesian coordinate system transverse to said first axis with respect to time;

(c) sensing a first force component at said stylus point at an intersection of said first axis and said second axis in a third axis related to orientation of said writing instrument with respect to time;

(d) sensing a second force component at said stylus point at said intersection of said first axis and said second axis in a fourth axis related to orientation of said writing instrument transverse to said third axis with respect to time; and

(e) sensing a third force component at said stylus point at an intersection of said first axis and said second axis in a fifth axis related to orientation of said writing instrument transverse to said third axis and to said fourth axis with respect to time;

(f) logging, with respect to a common time reference, said first position component, said second position component, said first force component, said second force component and said third force component to obtain force and position information relative to a common stylus point which is time correlated;

(g) combining said first and second position components and said first, second and third force components to produce output information; and

(h) providing said output information to an output device.

6. The method according to claim 5 wherein said combining step comprises the step of comparing logged position information and force information of an input with a template set to obtain figures of merit relative to a reference.

7. The method according to claim 6 further including obtaining a single figure of merit as said output information.

8. The method according to claim 6 wherein said comparing step comprises applying a rubbery correlation process in five dimensions corresponding to said first, second, third, fourth and fifth axes to obtain five figures of merit.

9. The method according to claim 6 wherein said comparing step comprises extracting features in five dimensions corresponding to said first, second, third, fourth and fifth axes, said features including total time of activity, average force along said third, fourth and fifth axes, and average distance along said first and second axes.

10. The method according to claim 5 further including the step of repeating said steps (a) through (g) a plurality of iterations under controlled conditions to establish a reference in the form of a template set.

11. The method according to claim 6 wherein said comparing step includes applying a root mean squared analysis between said logged information and information of said template set.

12. The method according to claim 9 wherein said comparing step includes applying a root mean squared analysis between said logged information and information of said template set.