Andre SeyfarthAndre Seyfarth

Hartmut GeyerHartmut Geyer

Fumiya IidaFumiya Iida

Leg design and Leg design and control of control of locomotionlocomotion

Zurich, 25 May 2004Zurich, 25 May 2004

Locomotion Lab Jena

LocomotionExperiments

NeuromechanicalModels

TechnicalImplementation

Gait Transitions

3D-instrumentedTreadmill

Gait specific control templates Legged Systems

Gait Orthesis

LocomotionExperiments

NeuromechanicalModels

TechnicalImplementation

Central hypothesisCentral hypothesis

To achieve periodic movement To achieve periodic movement patterns, an appropriate design patterns, an appropriate design criterion is required.criterion is required.

In our approach, In our approach, system system stabilitystability is such a criterion. is such a criterion.

Stability requirementsStability requirements

Internal

GlobalLeg Operation

Stability requirementsStability requirements

Internal

Leg Operation SegmentationSegmentation Control at Joint LevelControl at Joint Level

Stability requirementsStability requirements

Global Leg Operation Running Running Walking Walking Gait TransitionGait Transition

Part I Part I

InternalInternalLeg OperationLeg Operation

Biologically Inspired Biologically Inspired ApproachApproach

In many task, the leg behavior In many task, the leg behavior can be compared to a simple can be compared to a simple mechanical spring.mechanical spring.

Control of a Control of a segmented legsegmented leg

Idea

Control of a Control of a segmented legsegmented leg

Idea

Control of a Control of a segmented legsegmented leg

Idea

Control of a Control of a segmented legsegmented leg

Control of a Control of a segmented legsegmented leg

Solutions

Seyfarth et al. (2001) Biol. Cybern.

• Biarticular Structures (e.g. Muscles)

• Geometric Constraints (e.g. Heel pad)

+

Control at Joint LevelControl at Joint Level

Where does the muscle activation

for periodic movements come

from?

Control at Joint LevelControl at Joint Level

P(t)

STIM(t)

Geyer et al. (2003) Proc.Roy.Soc.B.

Positive Force

Feedback

Control at Joint LevelControl at Joint Level

Part II Part II

GlobalGlobalLeg OperationLeg Operation

Control of Pedal Locomotionstance phase swing phase

axial required optional‘leg spring’ bended leg

rotatory optional requirede.g. hip torque protraction

retraction

energetic stabilization

kinematic stabilization

RunningRunning

Spring Mass Running Spring Mass Running

fixed angle of attack

fixed leg stiffness

Seyfarth et al. (2002) J. Biomechanics

Spring Mass Running Spring Mass Running

RETRACTION

Seyfarth et al. (2003) J. Exp. Biol.

Spring Mass Running Spring Mass Running

Running in Horizontal Running in Horizontal PlanePlane

Running in Horizontal Running in Horizontal PlanePlane

Gait TransitionGait Transition

Gait TransitionGait Transition

Gait TransitionGait Transition

Leg f

orc

e (

N)

Leg f

orc

e (

N)

time (samples)

Leg compression (m)

WALK

RUN

RUN

WALK

Experimental Results

Gait TransitionGait TransitionExperimental Results

Gait TransitionGait TransitionExperimental Results

Gait TransitionGait TransitionExperimental Results

Gait TransitionGait Transition

New Theory

Max. Speed Inv. Pendulum

Gait TransitionGait TransitionExperimental Results

WalkingWalking

Spring Mass Walking Spring Mass Walking

Spring Mass Walking Spring Mass Walking

Spring Mass Walking Spring Mass Walking

A B C

Ground Reaction Ground Reaction

ForcesForces

Part III Part III

ImplicationsImplications

Link to RoboticsLink to Robotics

Origin of MovementsOrigin of Movements

Neural Program

MechanicalBehavior

??

Link to RoboticsLink to Robotics

Tight-Control Relaxed Control

Link to RoboticsLink to Robotics

Hard-Control

Link to RoboticsLink to Robotics

Contribution of back movements to Contribution of back movements to locomotion?locomotion?

Link to RoboticsLink to Robotics

Contribution of back movements to Contribution of back movements to locomotion?locomotion?

Link to RehabilitationLink to Rehabilitation

Decentralized leg control during Decentralized leg control during locomotionlocomotion Elastic knee joint during stance Elastic knee joint during stance phase?phase?

Thank you!Thank you!

Locomotion Lab at Jena University