Transcript Slides - 서울대학교
보행 예측 시뮬레이션
이 제 희
생체운동연구단 서울대학교
보행 예측 시뮬레이션 수술 전 보행 데이터 취득
모션 캡쳐, 지면 반발력, EMG 개인 별 골격, 근력, 근경직도
수술 계획에 따른 근골격 변형
골격 변형, 근육 길이, insertion, origin, tendon 길이
수술 후 보행 예측 시뮬레이션
시뮬레이션 평가
Newton’s Equation of Motion
mass force acceleration
f
ma
Dynamic Simulation q : state of the body
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t
)
a
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)
dt
q
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t
) (
t
)
dt f
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dt m
Integrate force over time
Path Tracking PD (Proportional Derivative) Control
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t
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q
exp (
t
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k v
exp (
t
) (
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k p
q
exp (
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q
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Articulated Figure q : Generalized state M : System mass matrix F : Gravity and External forces C : Coriolis and centripetal forces
t
: Joint forces
M q
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t
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C
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q
, ) t (
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F
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, )
Fully-Actuated System Forward dynamics Given (generalized) forces, compute (generalized) accelerations Inverse dynamics Given (generalized) accelerations, compute (generalized) forces
Under-actuated System Forward dynamics
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t
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M
1
C
(
q
, ) t (
q
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F
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, )
Inverse dynamics Given accelerations, we may not be able to compute forces that generate the desired accelerations
Ground Reaction Force (GRF) GRF is passive we actuate our muscles, but we can sense the magnitude of GRF we cannot control GRF precisely GRF is hemi-directional Precisely controllable GRF facilitates the control of underactuated system If GRF were omni-directional, the system is fully-actuated
Muscle Force Three-element Hill muscle model one contractile active element two 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 approach collection of 3D bone geometries (from CT) principle component analysis (PCA)
B
B average
c
1
B
1
c n B n