Methods and apparatus for handheld tool

• US 9,342,632 B2
• Filed: 03/04/2013
• Issued: 05/17/2016
• Est. Priority Date: 03/02/2012
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Zoran, Amit, Paradiso, Joseph, Shilkrot, Roy
• Primary Examiner(s): Rodriguez, Carlos Ortiz
• Assistant Examiner(s): Lin, Jason
• Application Number:
  US13/784,674
• Publication Number:
  US 20130231771A1
• Time in Patent Office: 1,170 Days
• Field of Search: 700/168
• US Class Current: 1/1
• CPC Class Codes: B44B 3/009 using a computer control means
• CPC Class Codes: G05B 19/4099 Surface or curve machining, making 3D objects, e.g. desktop manufacturing
• CPC Class Codes: G05B 2219/35134 3-D cad-cam
• CPC Class Codes: G05B 2219/49023 3-D printing, layer of powder, add drops of binder in layer, new powder
• CPC Class Codes: G06F 30/00 Computer-aided design [CAD]
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
• CPC Class Codes: Y02T 10/82 Elements for improving aerodynamics

Abstract

In exemplary implementations of this invention, a computer-assisted, handheld machining tool allows even an inexperienced user to carve a complex 3D object, while maintaining artistic freedom to modify the sculpture from an initial CAD design. The tool prevents the user from unintentionally removing material from a volume defined by the CAD design. It does so by slowing or halting spindle rotation as the bit approaches or penetrates the protected volume. The user can override this protective feature. The tool may operate in at least three interaction modes: (i) a static mode in which a static CAD model is used, where the computer assists by preventing the user from damaging the static model; (ii) a dynamic mode where the computer dynamically modifies the CAD model during the sculpting process; and (iii) an autonomous mode where the computer can operate independently of the user, for tasks such as semi-automatic texture rendering.

Claims

1. Apparatus comprising a machining tool and a tracking system, wherein:

(a) the tracking system is configured to track position of a bit of the machining tool relative to an object; and

(b) the machining tool;

(i) is configured to be handheld by a human user while effecting physical removal of material from the object, such that the weight of the tool is supported solely by a hand of the user during the removal,

(ii) is configured to be controlled depending on the tracked position of the bit relative to a protected region, such that the removal of material slows if the bit approaches to within a threshold distance from the protected region and stops if the bit penetrates inside the protected region, and

(iii) is configured to calculate, in response to a movement of the bit relative to the object during the physical removal of material, a change in the boundary of the protected region;

wherein the protected region is defined by a computer-aided design (CAD) model and has a boundary that is changeable.

2. The apparatus of claim 1, wherein slowing or stopping the removal of material is achieved by slowing or stopping a cutting speed, the cutting speed being the difference in speed between the bit and the object, not including feed rate.

3. The apparatus of claim 1, wherein the change in a boundary of the protected region minimizes the volume of material that needs to be removed from the object to achieve a target shape.

4. The apparatus of claim 1, wherein the change in the boundary of the protected region is computed by selecting, out of a set of virtual models of protected regions, a model that minimizes the volume of material that needs to be removed from the object to achieve a target shape.

5. The apparatus of claim 1, wherein the apparatus is further configured to actuate the bit to move in paths relative to the object that are not determined by the user.

6. The apparatus of claim 1, wherein the apparatus includes at least one sensor for detecting data indicative of position of the machining tool relative to the object.

7. The apparatus of claim 1, wherein the apparatus includes at least one sensor for detecting data indicative of pressure exerted by the machining tool on the object.

8. The apparatus of claim 1, wherein the apparatus includes one or more transducers for providing feedback to the user regarding at least one of a group consisting of:

(i) position of the machining tool relative to the object, or (ii) pressure exerted by the machining tool on the object.

9. The apparatus of claim 1, wherein slowing or stopping the removal of material is achieved by retracting a shaft of the machining tool, such that the shaft moves relative to a handle of the machining tool during the retracting.

10. The apparatus of claim 1, wherein:

(a) different virtual models of protected regions are used for different portions of the object, in accordance with selections inputted by the user; and

(b) the protected region is a hybrid protected region that does not correspond to any single virtual model of a protected region.

11. A method comprising:

(a) using a tracking system to track position of a bit of a machining tool relative to an object;

(b) controlling the machining tool, depending on the tracked position of the bit relative to a protected region, such that physical removal of material from the object slows if the bit approaches to within a threshold distance from the protected region and stops if the bit penetrates inside the protected region; and

(b) calculating, in response to a movement of the bit relative to the object during the physical removal of material, a change in the boundary of the protected region;

wherein

(i) the tool is configured to be supported solely by a hand of a user during the removal of material, and

(ii) the protected region is defined by a computer-aided design (CAD) model and has a boundary that is changeable.

12. The method of claim 11, wherein slowing or stopping the removal of material is achieved by slowing or stopping a cutting speed, the cutting speed being the difference in speed between the bit and the object, not including feed rate.

13. The method of claim 11, wherein the change in a boundary of the protected region minimizes the volume of material that needs to be removed from the object to achieve a target shape.

14. The method of claim 11, wherein the change in the boundary of the protected region is computed by selecting, out of a set of virtual models of protected regions, a model that minimizes the volume of material that needs to be removed from the object to achieve a target shape.

15. The method of claim 11, wherein the method further comprises actuating the bit to move in paths relative to the object that are not determined by the user.

16. The method of claim 11, wherein:

(a) different virtual models of protected regions are used for different portions of the object, in accordance with selections inputted by the user; and

(b) the protected region is a hybrid protected region that does not correspond to any single virtual model of a protected region.

17. The method of claim 11, wherein slowing or stopping the removal of material is achieved by retracting a portion of the tool.

18. Apparatus comprising a machining tool and a tracking system, wherein

(a) the tracking system is configured to track position of a removal site relative to an object;

and

(b) the machining tool;

(i) is configured to effect physical removal of material from the object, the removal of material having a removal rate and occurring at the removal site,

(ii) is configured to be handheld by a human user during the removal of material, such that the weight of the machining tool is supported solely by a hand of the user during the removal,

(iii) is configured to be controlled depending on the tracked position of the removal site relative to a protected region, such that the removal of material slows if the removal site approaches to within a threshold distance from the protected region and stops if the removal site penetrates inside the protected region, which protected region is defined by a computer-aided design (CAD) model and has a boundary that is changeable, and

(iv) is configured to calculate, in response to a movement of the removal site relative to the object during the physical removal of material, a change in the boundary of the protected region.

19. The apparatus of claim 18, wherein the change in a boundary of the protected region minimizes the volume of material that needs to be removed from the object to achieve a target shape.

20. The apparatus of claim 18, wherein slowing or stopping the removal of material is achieved by retracting a portion of the machining tool.