Transcript Muscle-Reflex Model That Encodes Principles of Legged

Muscle-Reflex Model That Encodes Principles
of Legged Mechanics Produces Human Walking
Dynamics and Muscle Activities
서울대학교
이경호
2012. 4. 06
Introduction
• Central Pattern Generator(CPG)
– complex network of neurons that controls
legged locomotion of animals and humans.
– in spinal cord
Introduction
• Principle of legged mechanics
– it can largely simplify locomotion control
– self-stability, compliant leg behavior
• How these principles integrated into
human motor control?
– spinal reflexes
– they can link sensory information into
activation of the leg muscles
Human Model
SOL : soleus
VAS : vasti
GAS : gastrocnemius
TA : tibialis anterior
GLU : gluteal muscles
HFL : hip flexor
muscles
HAM : hamstring
Muscle-tendon model
Muscle Control
• positive force feedback (F+)
S : stimulation
S0 : prestimulation
G : Gain
F : force
△t : time delay
Muscle-tendon model
A : muscle activation
fl : force-length relationship
fv : force-velocity relationship
Human Model
SOL : soleus
VAS : vasti
GAS : gastrocnemius
TA : tibialis anterior
GLU : gluteal muscles
HFL : hip flexor
muscles
HAM : hamstring
Muscle Control
• positive length feedback (L+)
Human Model
SOL : soleus
VAS : vasti
GAS : gastrocnemius
TA : tibialis anterior
GLU : gluteal muscles
HFL : hip flexor
muscles
HAM : hamstring
Muscle Control
• PD control
kp, kd : gain
: reference lean angle
Double Support
Actual Leg Swing Phase
During actual swing, we mainly rely on
a leg’s ballistic motion. The distal leg
muscles SOL, GAS, and VAS are silent
in that phase. Only TA’s L+, remains
active to provide foot clearance with
the ground
Pattern Generation
Result
• Walking Gait
- Matlab
SimMechanics
GRF : ground reaction force
Result
• Predict Motor Output
Result
• Adaptation to Slopes
Discussion
• Principles of legged mechanics explains
the basic dynamics of human locomotion
– encode several principles of legged
mechanics with actuators and control, which
turned into muscles and reflexes
• Is it sufficient?
– more principles of legged mechanics do
certainly exist
– level of detail
Discussion
• CPG vs Reflex
– Actual ratio of central and reflex inputs is
remain uncelar