Exploiting Natural Dynamics in the Control of a 3D Bipedal Walking Simulation Jerry Pratt, Gill Pratt MIT Leg Laboratory

Exploiting Natural Dynamics in Exploiting Natural Dynamics in the Control of a 3D Bipedal the Control of a 3D Bipedal

Walking SimulationWalking Simulation

Jerry Pratt, Gill PrattJerry Pratt, Gill Pratt

MIT Leg LaboratoryMIT Leg Laboratory

www.ai.mit.edu/projects/leglab/www.ai.mit.edu/projects/leglab/

M2 M2 3D Biped -- 12 DOF3D Biped -- 12 DOF

Designed by Daniel Paluska and David Robinson

M2 SimulationM2 Simulation3D Biped -- 12 DOF3D Biped -- 12 DOF

Spring FlamingoSpring FlamingoPlanar BipedPlanar Biped

6 DOF6 DOF

OutlineOutline

• Background:Background:– Previous WorkPrevious Work– Series Elastic ActuatorsSeries Elastic Actuators

• Natural Mechanisms for WalkingNatural Mechanisms for Walking

• Planar Robot Algorithm and Results Planar Robot Algorithm and Results

• 3D Simulation Algorithm and Results3D Simulation Algorithm and Results

• Conclusions and Future WorkConclusions and Future Work

Background: Previous WorkBackground: Previous Work

Background: Previous WorkBackground: Previous Work

Background: Previous WorkBackground: Previous Work

• Passive Dynamic WalkersPassive Dynamic Walkers– Natural LookingNatural Looking

– EfficientEfficient

– Simple (No) ControlSimple (No) Control

• Powered Bipedal RobotsPowered Bipedal Robots– Capability PotentialCapability Potential

– Practical/Market PotentialPractical/Market Potential

– Biological Similarity Biological Similarity PotentialPotential

PassiveWalkers

PoweredWalkers

Background: Background: Series Elastic ActuatorsSeries Elastic Actuators

MotorGearTrain

SeriesElasticity

Load

ForceSource

Load

Background: Background: Series Elastic ActuatorsSeries Elastic Actuators

Background: Background: Series Elastic ActuatorsSeries Elastic Actuators

Designed by David Robinson and Daniel Paluska

OutlineOutline

• BackgroundBackground• Natural Mechanisms for WalkingNatural Mechanisms for Walking

– KneecapKneecap– Compliant AnkleCompliant Ankle– Passive SwingPassive Swing

• Planar Robot Algorithm and Results Planar Robot Algorithm and Results • 3D Simulation Algorithm and Results3D Simulation Algorithm and Results• Conclusions and Future WorkConclusions and Future Work

KneecapKneecap

KneecapKneecap

Compliant AnkleCompliant Ankle

Compliant AnkleCompliant Ankle

Passive SwingPassive Swing

OutlineOutline

• BackgroundBackground

• Natural Mechanisms for WalkingNatural Mechanisms for Walking

• Planar Robot Algorithm and ResultsPlanar Robot Algorithm and Results

• 3D Simulation Algorithm and Results3D Simulation Algorithm and Results

• Conclusions and Future WorkConclusions and Future Work

Spring FlamingoSpring FlamingoPlanar BipedPlanar Biped

6 DOF6 DOF

Planar Robot AlgorithmPlanar Robot Algorithm

Planar Robot AlgorithmPlanar Robot Algorithm

• HeightHeight: Constant vertical : Constant vertical force.force.

• PitchPitch: PD controller on : PD controller on stance leg.stance leg.

• Swing LegSwing Leg: Mostly Passive.: Mostly Passive.

• SpeedSpeed: Naturally stable for : Naturally stable for slow speeds.slow speeds.

Title:clawar_flam_fig.epsCreator:fig2dev Version 3.2 Patchlevel 1Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

Robot Strobe PhotoRobot Strobe Photo

Planar Robot AnimationPlanar Robot Animation

Physical Robot Walking DataPhysical Robot Walking Data

OutlineOutline

• BackgroundBackground

• Natural Mechanisms for WalkingNatural Mechanisms for Walking

• Planar Robot Algorithm and Results Planar Robot Algorithm and Results

• 3D Simulation Algorithm and Results 3D Simulation Algorithm and Results

• Conclusions and Future WorkConclusions and Future Work

M2 SimulationM2 Simulation3D Biped -- 12 DOF3D Biped -- 12 DOF

Simple Foot Placement ModelSimple Foot Placement ModelTitle:(foot_placement.eps)Creator:Adobe Illustrator(R) 8.0Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

2

2

1mvEk

cos1 mglEp

gl

v

Simple Foot Placement ModelSimple Foot Placement ModelTitle:(foot_placement.eps)Creator:Adobe Illustrator(R) 8.0Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.fanklef mgwmgw

l

w

gl

v

l

w

gl

v ff

““Capture Angle”Capture Angle”Title:capture_angle.epsCreator:MATLAB, The Mathworks, Inc.Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

3D Simulation Algorithm3D Simulation AlgorithmTitle:sim_state_machine.epsCreator:fig2dev Version 3.2 Patchlevel 0-beta2Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

3D Simulation Animation3D Simulation Animation

Title:M2_cartoon.epsCreator:MATLAB, The Mathworks, Inc.Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

Simulation DataSimulation Data

Title:M2_sim_data.epsCreator:MATLAB, The Mathworks, Inc.Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

OutlineOutline

• BackgroundBackground

• Natural Mechanisms for WalkingNatural Mechanisms for Walking

• Planar Robot Algorithm and Results Planar Robot Algorithm and Results

• 3D Simulation Algorithm and Results3D Simulation Algorithm and Results

• Conclusions and Future WorkConclusions and Future Work

ConclusionsConclusions

• Passive Mechanisms Helped Make ControlPassive Mechanisms Helped Make Control– SimpleSimple– EfficientEfficient– Natural LookingNatural Looking

• Actuators with Negligible Dynamics are Actuators with Negligible Dynamics are ImportantImportant

• Decoupled Controller Works well for 3D Decoupled Controller Works well for 3D Simulation Walking StraightSimulation Walking Straight

Future WorkFuture Work

• Faster WalkingFaster Walking

• More Robust AlgorithmMore Robust Algorithm

• Biologically Similar AlgorithmBiologically Similar Algorithm

• Automatic Tuning, LearningAutomatic Tuning, Learning

• Central Pattern GeneratorsCentral Pattern Generators

• 3D Robot3D Robot

?

What Next?What Next?