Method and system for interactive simulation of materials

• US 20070239409A1
• Filed: 04/06/2007
• Published: 10/11/2007
• Est. Priority Date: 04/08/2006
• Status: Active Grant

• Current Assignee: Millman Alan
• Original Assignee: Millman Alan
• Inventors: Alan, Millman
• Granted Patent: US 8,395,626 B2
• Time in Patent Office: Days
• US Class Current: 703/2
• CPC Class Codes: G06F 2111/10 Numerical modelling
• CPC Class Codes: G06F 30/20 Design optimisation, verification or simulation optimisation, verification or simulation of circuit designs G06F30/30
• CPC Class Codes: G06F 30/23 using finite element methods [FEM] or finite difference methods [FDM]
• CPC Class Codes: G06T 13/00 Animation

Abstract

A method and system for interactive simulation of materials. The method and system provide flexible simulation, the ability to combine rigid and flexible simulation, a collision-detection method for simulating objects and other entities, and a system for displaying and interacting with simulated objects which includes a harness for registering the hardware components of the simulation with respect to each other.

Claims

1. A method for simulating rigid, semi-rigid, and flexible components of materials comprising:

obtaining a plurality of any of positions, velocities, and accelerations of components of an entity;

calculating a plurality of forces and optionally torques on the entity using any of the obtained positions, velocities, and accelerations; and

calculating one or more of any of positions, velocities, and accelerations of the entity using the calculated plurality of forces and optionally torques, and one or more force-transmission parameters.

2. The method of claim 1 further comprising a computer readable medium having stored therein instructions for causing one or more processors to execute the steps of the method.

3. The method of claim 1 wherein the obtaining step includes securely obtaining the plurality of any of positions, velocities, and accelerations of the entity simulated using a combination of a rigid-body method and a spring-and-dashpot method.

4. The method of claim 1 wherein the obtaining step includes securely obtaining the plurality of any of positions, velocities, and accelerations of an entity simulated using a combination of a rigid-body method and a finite-element method.

5. The method of claim 1 wherein one or more flexible components of an entity are simulated using hookian springs.

6. The method of claim 1 wherein one or more flexible components of an entity are simulated using orientation-preserving springs.

7. The method of claim 1 wherein one or more flexible components are simulated using a plurality of different types of orientation-preserving springs.

8. The method of claim 7 wherein the plurality of different types of orientation-preserving springs include using different types of simulated orientation-preserving springs depending upon whether or not an orientation-preserving spring is internal or external to the body or bodies of an entity.

9. The method of claim 8 wherein the internal orientation-preserving springs do not apply torques to their body or bodies.

10. The method of claim 1 wherein the step of calculating one or more of any of positions, velocities, and accelerations using the calculated forces and one or more force-transmission parameters includes calculating, for each body of an entity or entities:

a first portion of the body'"'"'s mass that moves in a rigid manner, and by inference, a second portion of the mass of the body that deforms independently of the body, using force-transmission parameters associated with each of the components of the body;

a partial acceleration of each component of the body that is independent of the motion of the body as a whole, and a partial acceleration of each component that is due to the acceleration of the body as a whole;

an independent change in position and velocity of each of the components of the body, due to a deformation (A);

a change in position and velocity of the body as a whole, due to a rigid motion (B);

a position and velocity of each of the components of the body relative to the body'"'"'s center-of-mass; and

an actual change in position and velocity of each of the components of the body, including both (A), (B), and each component'"'"'s force-transmission parameter.

11. The method of claim 1 wherein the step of calculating one or more of any of positions, velocities, and accelerations using the calculated torques and one or more force-transmission parameters includes calculating, for each body of an entity or entities:

a total torque on the body;

an amount of force-transmission of the body;

a body'"'"'s change in angular momentum, involving the force-transmission of the body;

a body'"'"'s angular velocity (A) and angular acceleration;

a linearized angular velocity of each of the components of the body;

optionally, centrifugal and coriolis accelerations of each of the components of the body (B);

a change, due to rotation, in position and velocity of each of the components of the body, including (A), optionally (B), and each component'"'"'s force-transmission parameter; and

optionally, a change in orientation of the body'"'"'s orthonormal basis reference frame.

12. The method of claim 6 wherein rest length(s) and orientation(s) of one or more orientation-preserving springs are changed over time.

13. The method of claim 1 wherein force-transmission parameter(s) of one or more components of an entity are changed over time.

14. The method of claim 13 wherein the change in the force-transmission parameter of one or more components of an entity is due to any of:

a) physical properties of a material under compression,

b) response to external forces,

c) tables of data or functions residing in a computer database or memory,

d) response to user input, or a combination thereof.

15. The method of claim 1 wherein the entity includes a component of a human body.

16. The method of claim 15 wherein the component of the human body includes any of muscle, bone, and connective tissue.

17. The method of claim 1 wherein the obtaining step includes obtaining one or more of any of positions, velocities, and accelerations of one or more haptic devices that sense any of positional information, rotational information, hand motion, and other motion from a user input and return one or more push-back forces to the user, allowing the feel of any of resistance, collision, penetration, separation, cutting, tearing, breakage, and other motions of one or more materials of a simulated entity or entities.

18. The method of claim 1 wherein orientation-preserving springs are used for creating dynamic motion in a material or body, comprising:

using one or more orientation-preserving springs between components of an entity; and

changing a rest-vector of one or more orientation-preserving springs over time.

19. The method of claim 18 wherein one or more rest-vectors of the orientation-preserving springs are changed over time according to any of:

a) predetermined key-frame positions,

b) tables of data or functions residing in a computer database or memory,

c) response to user input, or a combination thereof.

20. The method of claim 1 further comprising displaying the calculated one or more positions, and optionally any of velocities and accelerations of the entity as a two-dimensional (2D) or three dimensional (3D) simulated view of a representation of the entity or sub-portions thereof.

21. The method of claim 1 further comprising storing physical information about a 3D model in its color data, such that each component of a four-component color maps to one of the physical quantities of mass, stiffness, damping, and force-transmission.

22. A method for use of orientation-preserving springs for creating a permanent or semi-permanent shape change in a material or body, comprising:

using one or more orientation-preserving springs between components of an entity; and

modifying a rest-vector of the one or more orientation-preserving springs.

23. The method of claim 22 wherein the one or more rest-vectors of the orientation-preserving springs are modified as a result of any of:

a) one or more collisions,

b) a plastic change in a material due to internal or external forces,

c) a response to user input, or a combination thereof.

24. A method for specifying and using a normalized value for calculating a damping value of a spring, comprising:

defining and assigning to a spring a normalized value representing damping of the spring, such that a normalized value of zero represents an absence of damping, a normalized value of less than one represents underdamping, a normalized value of one represents critical damping, and a normalized value of greater than one represents overdamping; and

using the assigned normalized value to calculate the spring'"'"'s actual damping value, so that the spring exhibits the damping response specified by the normalized value.

25. A system for providing absolute positional and rotational registration of and rigidly connecting an entity comprising in combination:

one or more display devices, optionally attached to a mechanical linkage by which the one or more display devices are dynamically repositioned during a simulation, the new positions optionally being dynamically reported in real time by mechanical or other sensors for use in the simulation; and

one or more position-sensing devices, optionally attached to a mechanical linkage by which they can be dynamically repositioned during a simulation, the new positions optionally being dynamically reported in real time by mechanical or other sensors for use in the simulation.

26. The system of claim 25 wherein the position-sensing device is also a haptic device.

27. The system of claim 25, further comprising allowing absolute positional and rotational registration of and including one or more of any of eye- and head-tracking devices.

28. A system for simultaneously simulating rigid and flexible components of an entity, comprising in combination:

means for simulating flexible components of an entity using orientation-preserving springs;

means for simulating flexible, rigid, and semi-rigid components of the entity using one or more force-transmission parameters;

means for applying a pre-determined collision detection method to detect collisions between any of one or more representations of haptic or position-sensing devices, one or more entities, and one or more subcomponents of one or more entities, to create collision-free representations of haptic or position-sensing devices, entities and subcomponents; and

means for displaying a representation of the collision-free components as a two-dimensional (2D) or three-dimensional (3D) simulation view of each entity or subportions thereof.

29. The system of claim 28, further comprising means for rigidly connecting, optionally dynamically moving during a simulation, and registering with respect to each hardware component of the simulation, including one or more display devices, one or more position-sensing devices, and optionally one or more tracking devices.

30. A system for simultaneously simulating rigid and flexible components of an entity, comprising in combination:

means for obtaining or calculating a plurality of positions, velocities, and optionally accelerations for combined rigid and flexible components of an entity using a spring and dashpot model;

means for calculating a plurality of forces and optionally torques on the entity using any of the obtained positions, velocities, and accelerations;

means for calculating one or more of any of positions, velocities, and accelerations of the entity and its components using the calculated plurality of forces and optionally torques; and

means for displaying a two-dimensional (2D) or three-dimensional (3D) simulation view, wherein the view may contain a representation of any of one or more entities, their components, or subportions thereof.

31. The system of claim 30, further comprising means for rigidly connecting, optionally dynamically moving during a simulation, and registering with respect to hardware components of the simulation, including one or more display devices, one or more position-sensing devices, and optionally one or more tracking devices.