보행 예측 시뮬레이션

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생체운동연구단서울대학교

보행 예측 시뮬레이션

수술 전 보행 데이터 취득모션 캡쳐 , 지면 반발력 , EMG개인 별 골격 , 근력 , 근경직도

수술 계획에 따른 근골격 변형골격 변형 , 근육 길이 , insertion, origin, tendon 길이

수술 후 보행 예측 시뮬레이션시뮬레이션 평가

Newton’s Equation of Motion

force

mass

acceleration

maf

Dynamic Simulation

q : state of the body

Integrate force over time

dttqtq

dtmtfdttatq

)()(

)()()(

Path Tracking

)()()()()()( expexpexp tqtqktqtqktqtq pv

PD (Proportional Derivative) Control

Articulated Figure

q : Generalized stateM : System mass matrixF : Gravity and External forcesC : Coriolis and centripetal forcest : Joint forces

),()(),()( qqFqqqCtqM t

Fully-Actuated System

Forward dynamicsGiven (generalized) forces,compute (generalized) accelerations

Inverse dynamicsGiven (generalized) accelerations,compute (generalized) forces

Under-actuated System

Forward dynamics

Inverse dynamicsGiven accelerations, we may not be able to compute forces that generate the desired accelerations

),()(),()( 1 qqFqqqCMtq t

Ground Reaction Force (GRF)GRF is passive

we actuate our muscles, butwe can sense the magnitude of GRFwe cannot control GRF precisely

GRF is hemi-directionalPrecisely controllable GRF facilitates

the control of underactuated systemIf GRF were omni-directional,

the system is fully-actuated

Muscle Force

Three-element Hill muscle modelone contractile active elementtwo passive non-linear springs

Actuator redundancy

Technical Issues

Placing markers for motion capture

Acquiring individual skeletal models

Individual Skeletal Models

Reconstruct bone shapes from multiview X-ray images

Model-based approachcollection of 3D bone geometries (from CT)principle component analysis (PCA)

nnaverage BcBcBB 11