Andre Seyfarth Hartmut Geyer Fumiya Iida Leg design and control of locomotion Zurich, 25 May 2004 Locomotion Lab Jena

Locomotion Experiments Neuromechanical Models Technical Implementation Gait Transitions 3D-instrumented Treadmill Gait specific control templates Legged Systems Gait Orthesis

Locomotion Experiments Neuromechanical Models Technical Implementation

Central hypothesis To achieve periodic movement patterns, an appropriate design criterion is required. To achieve periodic movement patterns, an appropriate design criterion is required. In our approach, system stability is such a criterion. In our approach, system stability is such a criterion.

Stability requirements InternalGlobalLeg Operation

Stability requirements InternalLeg Operation Segmentation Segmentation Control at Joint Level Control at Joint Level

Stability requirements GlobalLeg Operation Running Running Walking Walking Gait Transition Gait Transition

Part I Internal Leg Operation Internal Leg Operation

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

Control of a segmented leg Idea

Control of a segmented leg Idea

Control of a segmented leg Idea

Control of a segmented leg

Solutions Seyfarth et al. (2001) Biol. Cybern. Biarticular Structures (e.g. Muscles) Geometric Constraints (e.g. Heel pad) +

Control at Joint Level Where does the muscle activation for periodic movements come from?

Control at Joint Level  P(t) STIM(t) Geyer et al. (2003) Proc.Roy.Soc.B. Positive Force Feedback

Control at Joint Level

Part II Global Leg Operation

Control of Pedal Locomotion stance phaseswing phase axialrequiredoptional ‘leg spring’bended leg rotatoryoptionalrequired e.g. hip torque protraction retraction energetic stabilization kinematic stabilization

Running

Spring Mass Running fixed angle of attack fixed leg stiffness Seyfarth et al. (2002) J. Biomechanics

Spring Mass Running RETRACTION Seyfarth et al. (2003) J. Exp. Biol.

Spring Mass Running

Running in Horizontal Plane

Gait Transition

Leg force (N) time (samples) Leg compression (m) WALK RUN WALK Experimental Results

Gait Transition Experimental Results

Gait Transition Experimental Results

Gait Transition Experimental Results

Gait Transition New Theory Max. Speed Inv. Pendulum

Gait Transition Experimental Results

Walking

Spring Mass Walking

ABC Ground Reaction Forces

Part III Implications

Link to Robotics Origin of Movements Neural Program Mechanical Behavior ?

Link to Robotics Tight-ControlRelaxed Control

Link to Robotics Hard-Control

Link to Robotics Contribution of back movements to locomotion?

Link to Robotics Contribution of back movements to locomotion?

Link to Rehabilitation Decentralized leg control during locomotion  Elastic knee joint during stance phase?

Thank you! Locomotion Lab at Jena University