Muscle-Reflex Model That Encodes Principles of Legged Mechanics Produces Human Walking Dynamics and Muscle Activities 서울대학교 이경호

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