GB2393803A

GB2393803A - Two mode creature simulaton

Info

Publication number: GB2393803A
Application number: GB0222697A
Authority: GB
Inventors: Colin Andrew Low; David Trevor Cliff; Rycharde Jeffery Hawkes
Original assignee: Hewlett Packard Co
Current assignee: HP Inc
Priority date: 2002-10-01
Filing date: 2002-10-01
Publication date: 2004-04-07
Also published as: GB0222697D0; US20040133354A1; JP2004157990A

Abstract

A technique for simulating the activities of a large number of creatures is described. The technique utilises two modes of simulation. The first mode of simulation is arranged to simulate the activities of all of the creatures. The second mode of simulation is arranged to simulate the activities of a few of the creatures, at a more detailed level than the first mode. The second mode is utilised by the first mode to determine new parameters of individual creatures when the creatures undergo a change in environment.

Description

I. 2393803

TWO MODE CREATURE SIMULATION

Field of the Invention

The present invention relates to a method and a device suitable for simulating the activities of a plurality of creatures. 10 Background of the Invention

One of the problems with studying life sciences is that changes in ecosystems and the evolution of life forms takes place over long periods of time. Consequently, life 15 processes have been simulated in a variety of formats, thus allowing the study of the interaction of creatures and the emerging population patterns.

An animat is an artificial creature which exhibits an 20 active and purposeful behaviour in an environment which presents it with problems obstacles, navigation, hazards, goals. Animats are often inspired by biological organisms, which are observed to solve complex problems in real physical environments. Indeed, animate may be 25 designed to be as close as possible to the original biological organisms, so as to model the potential behaviour and/or evolution of such organisms.

Although it is possible to build physical robots to study 30 problems of this nature, there is a strong incentive to simulate both animat and environment together using computational models of (for example) sensors, actuators, neural networks and the Newton-Euler laws of rigid body

dynamics. Computational models permit the creation of large populations of simulated animate so that evolutionary situations can be studied. Use of physical robots to simulate large populations is impractical, as 5 the robots will suffer from wear and tear, break downs, and require significant capital and support costs.

Simulations of this type are also becoming increasingly popular in entertainment applications.

lo Experience with such simulated animate in an environment with realistic simulated physics shows that a modern computer (for instance, a 1 GHz Pentium computer) can simulate only a few (i.e. less than 10) animate in real time. A generic example of a simulation that uses 15 "realistic simulated physics,, is the 1994 work of Karl Simms, for instance as published in pages 28-39, "Evolving 3D morphology and behaviour by competition", in the book "Artificial Life IV" edited by Rod Brooks and Pattie Maes, published by M.I.T. Press. For evolutionary simulations, 20 it is desirable that populations of thousands are simulated at speeds of 10 to 100 times real time. It will thus be appreciated that the computational resource available on a typical desktop PC is inadequate by a significant factor (e.g. a factor of around 105 - 106) to 25 allow such a simulation.

Whilst it will be appreciated that the power of computers is continually increasing, it will also be appreciated that simulations tend to increase in complexity over time, 30 so as to allow more accurate simulations of real world situations e.g. so as to provide complex animate with the intelligence to solve real-world problems.

It is an aim of the present invention to provide a simulation technique that allows efficient usage of the available computational power, regardless of the processing power of the computer.

Statement of the Invention

In a first aspect, the present invention provides a method of simulating the activities of a plurality of creatures, lo the method comprising utilising at least two modes of simulation: a first mode arranged to simulate the activities of all of said creatures; and a second mode arranged to simulate the activity of at 15 least one of said creatures at a more detailed level than said first mode.

Preferably, said second mode of simulation is utilised when it is detected that one or more of said creatures 20 simulated by said first mode is undergoing a change in environment, the second mode being utilised to simulate the activity of the creatures undergoing the change in environment. 25 Preferably, said change in environment comprises a creature undergoing at least one of: fighting; mating; eating; interacting with another creature; reproducing; sensing another creature; encountering another creature; moving to a new terrain type; altering the environment.

Preferably, the second mode is invoked at the start of the simulation so as to determine the starting parameters of each creature.

Preferably, said second mode is utilised to determine at least one parameter affecting the activity of the simulated creature, said parameter being subsequently 5 utilised by the first mode of simulation.

Preferably, when the method changes from utilising the second mode to the first mode, at least one parameter relating to said creature simulated by the second mode is lo stored for use by a later iteration of the second mode.

Preferably, the above parameters comprise at least one of creature mass; creature energy; creature strength; creature behaviour transition probabilities; creature 15 biochemical levels; creature movement parameters; creature speed; creature rate of turn.

In a further aspect, the present invention provides a computer program arranged to perform the method as 20 described above.

In another aspect, the present invention provides a recordable medium comprising a computer program.

25 In a further aspect, the present invention provides a simulator device arranged to simulate the activities of a plurality of creatures, the device being arranged to utilise at least two modes of simulation: a first mode arranged to simulate the activities of all of 30 said creatures; and a second mode arranged to simulate the activity of at least one said creatures at a more detailed level than said first mode.

Brief Description of the Drawing

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, 5 reference will now be made, by way of example, to the accompanying diagrammatic drawing in which: Figure 1 shows a flow chart indicating a simulation technique in accordance with an embodiment of the present lo invention.

Detailed Description of Preferred Embodiment

The preferred embodiment utilises a large scale low 15 fidelity simulation (Lo-Fi Sim) arranged to simulate the activities of a large number of animate. Such a Lo-Fi Sim is typically used to simulate at least 10,000 animate, but could for instance be utilised to simulate even larger numbers e.g. 100,000, 1,000,000, 10,000,000 animate or 20 greater.

The Lo-Fi Sim (shown in figure 1 as step 100) is arranged to provide a simulation utilising good approximations of the macroscopic behaviour of an animal.

The Lo-Fi Sim has programmatic access to a simulation capable of modelling a small number of animate in greater detail, using all relevant physical details in a high fidelity simulation (the Hi-Fi Sim, 120).

The Lo-Fi Sim (100), utilising the macroscopic parameters is adequate at describing the animat during most of the simulation. However, when the animat encounters a change

in its environment (110) that can not be adequately modelled using the LoFi Sim then the Hi-Fi Sim (120) is used to determine the performance of the animat in the new environment. The Hi-Fi Sim can then pass the results 5 (e.g. the new parameters, or new values of previous parameters) back to the Lo-Fi Sim.

Thus the Hi-Fi Sim, operating as a slave program of the Lo-Fi Sim can measure the performance of an animat under lo various conditions that need to be tested (such as a change in terrain type), and return a test report to the Lo-Fi Sim. The Lo-Fi Sim will then utilise the results of the test report in the form of macroscopic parameters to provide an efficient simulation of the large number of 15 creatures.

In the preferred embodiment, the Hi-Fi-Sim is utilised to determine the speed of an animat when it reaches a new particular type of terrain by accurately modelling the 20 movements of the individual limbs of the animat over the terrain to determine an average speed. This average speed is then be passed back to the Lo-Fi Sim.

An approximation used in the Lo-Fi Sim is that the animate 25 travel in straight lines between significant changes in sensory inputs or over environment terrain types. The Lo-

Fi Sim requires information on the speed of a particular animat on a particular terrain type. This information is determined by placing the animat in a portion of the Hi-Fi 30 Sim (the "Test Engine") that tests the animat under conditions relevant to the Lo-Fi Sim.

For example, the Test Engine tests a particular animat for the following attributes: Straight line speed on terrain type A (e.g. smooth) Straight line speed on terrain type B (e.g. rough) 5 Straight line speed on terrain type C (e.g. creature ascending slope of 10) Straight line speed on terrain type D (e.g. creature descending slope of 10) Straight line speed on terrain type E (e.g. creature lo traversing 10 slope) Rate of turn of creature (e.g. in radians per second) Respective energy consumption rate required on terrain types A, B. C, D and E. 15 Thus, by only invoking the more detailed Hi-Fi Sim when required, and otherwise the less computationally intensive Lo-Fi Sim to otherwise model the activities of the animate, it will be appreciated that efficient use is made of the available computational resource. This enables 20 large populations of animate (or other creatures) to be modelled to a fair degree of accuracy on a relatively low power computer.

Whilst the above embodiment has been described in terms of 25 animate, it will be appreciated that the technique could be performed upon a simulation of any creature, artificial or otherwise. The artificial creature could be based upon a real creature or person.

30 Equally, whilst the above embodiment has provided the example of the change in environment being a change in terrain, it will be appreciated that other changes in the environment could lead to the Hi-Fi Sim being invoked.

For example, two animate may meet and interact (e.g. fight or mate) in a way that could only be modelled in the Hi-Fi Sim. The Hi-Fi Sim would thus be invoked programmatically by the Lo-Fi Sim to carry out a detailed simulation of 5 such an encounter (using a portion of the Hi-Fi Sim called the "Encounter Engine") and the animate may then be retested by the Test Engine if the encounter is likely to have caused a change that will influence the speed of the animat (e.g. it is "hurt" or low on energy, and thus lo unable to travel so quickly). In this way the Lo-Fi Sim continues to use the best available approximation to the animal's behaviour, invoking the Hi-Fi Sim when necessary to preserve validity in the overall simulation.

15 Preferably, the Hi-Fi Sim is arranged to use computationally expensive techniques for modelling of aspects such as behaviour selections, sensing and interaction with the environment and other animate, and uses a full, 3-D rigid-body physics simulation. The Lo-Fi 20 Sim is arranged to use only a 2-D (or 2.5D) physics simulation. It will be appreciated that whilst the preferred embodiment has described the simulation in terms of two 25 separate modes (a Lo-Fi Sim and a Hi-Fi Sim), equally the invention could be implemented utilising one or more modes that microscopically simulate the animate activities (i.e. One or more Lo-Fi Sims, each Sim providing a relatively coarse level of simulation) in conjunction with one or 30 more detailed simulation modes (e.g. a separate Test Engine, a separate Encounter Engine etc. each mode being directed to simulating a different change in the environment of one or more animate).

It will be appreciated that, as the Lo-Fi Sim uses a relatively coarse level of simulation, then when the test report from the Hi-Fi Sim is passed to the Lo-Fi Sim 5 detailed information about the animat activities and the animat simulated in the Hi-Fi Sim could be lost. For consistency when performing Hi-Fi Simulations, this is undesirable. lo Preferably, when an animat is transferred from the Hi-Fi Sim to the Lo-Fi Sim, information is extracted from the Hi-Fi Sim that is used directly within the Lo-Fi Sim.

Secondly, detailed information about the animat is stored, so that the next time the particular animat (or type of 15 animal) is modelled by the Hi-Fi Sim, such information can be recalled and utilised so as to provide the best possible simulation of the animal.

For instance, an animat may consist of a number of body 20 parts, each body part having an associated energy level, mass and strength.

Information on the sum of each of these parameters might be utilised within the Lo-Fi Simulation i.e. the total 25 energy stored within the animal, the total mass of the animat and the total strength stored within the animal.

However, within the Hi-Fi Sim, each of the respective body parts is simulated, and consequently each parameter has to be known with respect to each body part i.e. the energy 30 level, the individual mass, and the individual strength of each body part of the animal.

In order to preserve such information when exiting the Hi-

Fi Sim, as only the totals of these parameters is passed to the Lo-Fi Sim, then information on the distribution of energy, mass and strength across each body part is stored 5 ready for the next time the animat enters the Hi-Fi Sim.

The total energy, mass or strength of the animat may change whilst in the Lo-Fi Sim. Thus, when the animat next enters the Hi-Fi Sim, the appropriately resealed lo parameters for each body part can be calculated by utilising the total energy, total mass, total strength values from the Lo-Fi Sim and the recorded distribution of the proportion of such energies, mass and strength within each body part to accurately determine the new values of 15 energy, mass and strength for each individual body part.

In normal operation, as part of the initialization process of the simulation, the Hi-Fi Sim will be invoked to determine macroscopic parameters for all animate, either 20 by detailed modelling of each animal, or detailed modelling of each type of animal.

Whilst the above embodiment has been described with reference to an animal, it will be appreciated any 25 artificial autonomous agent including representations of: animals (known or imagined), vehicles (known or imagined), or robots (known or imagined) could be used in a simulation in accordance with alternative embodiments of the present invention. Such agents (or creatures) can be 30 arranged to interact with a simulated environment that may be based on a real-world environment.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and

which are open to public inspection with this 5 specification, and the contents of all such papers and

documents are incorporated herein by reference.

All of the features disclosed in this specification

(including any accompanying claims, abstract and lo drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

15 Each feature disclosed in this specification (including

any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each 20 feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any 25 novel one, or any novel combination, of the features disclosed in this specification (including any

accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS:

1. A method of simulating the activities of a plurality of creatures, the method comprising utilising at least two 5 modes of simulation: a first mode arranged to simulate the activities of all of said creatures; and a second mode arranged to simulate the activity of at least one of said creatures at a more detailed level than lo said first mode.

2. A method as claimed in claim 1, wherein said second mode of simulation is utilised when it is detected that one or more of said creatures simulated by said first mode 15 is undergoing a change in environment, the second mode being utilised to simulate the activity of the creatures undergoing the change in environment.

3. A method as claimed in claim 2, wherein said change in 20 environment comprises a creature undergoing at least one of: fighting; mating; eating; interacting with another creature; reproducing; sensing another creature; encountering another creature; moving to a new terrain type; altering the environment.

4. A method as claimed in any one of the above claims, wherein the second mode is invoked at the start of the simulation so as to determine the starting parameters of each creature.

5. A method as claimed in any one of the above claims, wherein said second mode is utilised to determine at least one parameter affecting the activity of the simulated

creature, said parameter being subsequently utilised by the first mode of simulation.

6. A method as claimed in any one of the above claims, 5 wherein when the method changes from utilising the second mode to the first mode, at least one parameter relating to said creature simulated by the second mode is stored for use by a later iteration of the second mode.

lo

7. A method as claimed in any one of claim 4, claim 5 or claim 6, wherein said parameter comprises at least one of creature mass; creature energy; creature strength; creature behaviour transition probabilities; creature biochemical levels; creature movement parameters; creature 15 speed; creature rate of turn.

8. A computer program arranged to perform the method as claimed in any one of the above claims.

20

9. A recordable medium comprising a computer program as claimed in claim 8.

10. A simulator device arranged to simulate the activities of a plurality of creatures, the device being arranged to 25 utilise at least two modes of simulation: a first mode arranged to simulate the activities of all of said creatures; and a second mode arranged to simulate the activity of at least one said creatures at a more detailed level than 30 said first mode.