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Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1,...
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Transcript of Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1,...
![Page 1: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/1.jpg)
Capture Point: A Step toward Humanoid Push Recovery
Jerry Pratt1, John Carff1, Sergey Drakunov1,
Ambarish Goswami2
1Florida Institute for Human and Machine Cognition2 Honda Research Institute
Humanoids 2006December 6, 2006
![Page 2: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/2.jpg)
Capture Point: A Step toward Humanoid Push Recovery
![Page 3: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/3.jpg)
Some Push Recovery Approaches
• Replan trajectories.
• Solve Constrained Optimization Problem.
• Machine Learning.
• Heuristics based on intuition and simple models.
![Page 4: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/4.jpg)
Outline• Push Recovery Overview
• Our Approach to Push Recovery.
• Simulation Examples.
• Ongoing and Future Work.
![Page 5: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/5.jpg)
Importance of Push Recovery
• Bipedal robots in human environments:– Bumping into objects.– Incidental contact when walking down a sidewalk.– Tripping over cluttered floors.– Contact during sports.– Intentional pushes.– Method of human input interface.
• Understanding and Assisting Humans– Falls are a major cause of injury.
![Page 6: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/6.jpg)
Theoretical and Practical Difficulties of Push Recovery
• Non-linear dynamics • Multi-variable dynamics• Limited foot-ground interaction• Hybrid dynamics (dynamics are both continuous
and change discretely during steps)• Quick detection of push required.• Fast reaction speed required.• Relatively large actuator power required.
![Page 7: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/7.jpg)
Human Push Recovery Strategies
• Move the Center of Pressure, predominately through ankle torques.
• Accelerate Angular momentum by “lunging” and “windmilling”. [Video]
• Take a step. [Video]
• Combinations. [Video1, Video2]
![Page 8: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/8.jpg)
Why these Strategies Work
• Broomstick (Inverted Pendulum) Analogy
• Tightrope Walker Analogy
![Page 9: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/9.jpg)
Using Angular Momentum effectively increases the size of
your footprint
[Popovic, Goswami, Herr IJRR2005]
![Page 10: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/10.jpg)
Outline
• Push Recovery Overview
• Our Approach to Push Recovery.
• Simulation Examples.
• Ongoing and Future Work.
![Page 11: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/11.jpg)
Capture Points and Capture Regions (Quick Definition)
• Capture Point: Point that the biped can step to and stop in one step without falling down.
• Capture Region: Set of all Capture Points.F
![Page 12: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/12.jpg)
Balance Strategy 1: Center of Pressure
Kinematic Workspace Of Swing Leg
Support Foot
Capture Region
![Page 13: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/13.jpg)
Balance Strategy 2:Accelerate Angular Inertia
(“Windmill” or “Lunge”)Kinematic Workspace Of Swing Leg
Support Foot
Capture Region
![Page 14: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/14.jpg)
Balance Strategy 3:Take a Step
Kinematic Workspace Of Swing Leg
Support Foot
Capture Region
![Page 15: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/15.jpg)
Balance Strategies 4,5,6:Multiple Steps, Run, or Fall
Kinematic Workspace Of Swing Leg
Support Foot
Capture Region
![Page 16: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/16.jpg)
How to Compute Capture Points?
• Simple Models with Closed-Form Solutions.
• Numerical Search
• Learning
![Page 17: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/17.jpg)
Computing the Capture Point for the Linear Inverted Pendulum (Kajita and Tani 1991) Model
![Page 18: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/18.jpg)
Computing Capture Points for the Linear Inverted Pendulum plus Flywheel Model
![Page 19: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/19.jpg)
Deriving Linear Inverted Pendulum Plus Flywheel Dynamics using
Similar Triangles
Mg
z0
X- /Mg
Fx
![Page 20: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/20.jpg)
Computing Capture Points for the Linear Inverted Pendulum plus Flywheel Model
• Flywheel is torque-limited due to motors.
• Flywheel is position limited to model humanoid upper body.– Greatest effect the flywheel can have is
through a bang-bang torque profile so that the flywheel accelerates and decelerates as quickly as possible, stopping at its maximum or minimum angle limit.
![Page 21: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/21.jpg)
Computing Capture Points for the Linear Inverted Pendulum plus Flywheel Model
• Bang-bang torque profile• Solve for TR1 and TR2 given initial and final states
of the flywheel.• Since dynamics are linear and torque profile has
Laplace Transform, everything can be computed in closed form.
![Page 22: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/22.jpg)
State Trajectories
![Page 23: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/23.jpg)
Projection of Phase Portrait
![Page 24: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/24.jpg)
Dynamic Evolution of Capture Points
• Using Linear Inverted Pendulum Model, dynamic evolution can be computed in closed form.
![Page 25: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/25.jpg)
Outline• Push Recovery Overview
• Our Approach to Push Recovery.
• Simulation Examples.
• Ongoing and Future Work.
![Page 26: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/26.jpg)
Push Recovery from Impulsive Push
![Page 27: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/27.jpg)
Stopping in one step by lunging
![Page 28: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/28.jpg)
Applying Linear Inverted Pendulum based Capture Point to 12 dof 3D model
![Page 29: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/29.jpg)
Stepping Stones by “guiding” the Capture Point to the Desired Stepping Point
![Page 30: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/30.jpg)
Take Home Message 1
• Precise foot placement is not necessary for push recovery, but good foot placement is.– If any point of the foot is placed inside the
Capture Region, the humanoid can stop.– Larger feet and/or more angular momentum
increase robustness to poor foot placement.
![Page 31: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/31.jpg)
Take Home Message 2
• Simple Models can be Useful!– Understanding of the fundamental principles.– Control Algorithm Development.
![Page 32: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/32.jpg)
Future Work
• Apply to a real humanoid.• Derive closed form calculations of Capture
Points for arbitrary CoM height trajectory.• Numerically compute Capture Regions for
complex models and compare to simple models.• Extend to persistent pushes.• Expand techniques to other aspects of walking:
– Dynamic Turning.– Rough Terrain.
![Page 33: Capture Point: A Step toward Humanoid Push Recovery Jerry Pratt 1, John Carff 1, Sergey Drakunov 1, Ambarish Goswami 2 1 Florida Institute for Human and.](https://reader035.fdocuments.net/reader035/viewer/2022062318/55155273550346c77d8b6625/html5/thumbnails/33.jpg)
Capture Point: A Step toward Humanoid Push Recovery
Jerry Pratt1, John Carff1, Sergey Drakunov1,
Ambarish Goswami2
1Florida Institute for Human and Machine Cognition2 Honda Research Institute
Humanoids 2006December 6, 2006