H kazerooni human engineering laboratory hel university of california at berkeley
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ONR Site Visit August 9, 2000. H. Kazerooni Human Engineering Laboratory (HEL) University of California at Berkeley. Topics 1. Ground Reaction Force Control 2. Frequency Matching Control. EXAMPLE. f. g. b. c. a. d. Path Generation. Power Terrain. One motor powers all legs. 2. 4.

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H. Kazerooni Human Engineering Laboratory (HEL) University of California at Berkeley

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H kazerooni human engineering laboratory hel university of california at berkeley

ONR Site VisitAugust 9, 2000

H. Kazerooni

Human Engineering Laboratory (HEL)

University of California at Berkeley


Topics 1 ground reaction force control 2 frequency matching control

Topics1. Ground Reaction Force Control2. Frequency Matching Control


Example

EXAMPLE

f

g

b

c

a

d


Path generation

Path Generation


Power terrain

Power Terrain

  • One motor powers all legs


Flexible feet construction

2

4

3

2

1

1

2

4

3

4

3

Flexible Feet Construction

  • Shape Deposition Modeling (SDM)

  • Simple Spring Legs

    Control system is embedded in hardware

    (Elasticity, Damping, and Mass of Legs)


Frequency matching

Trajectory of center of mass

Frequency Matching

  • Inverse Pendulum Model

  • Frequency of Walking (pendulum) α

    Natural Frequency of Leg (spring)

  • In fact, for cockroach,

    Freq. of Walking ≈ fnof 3 legs / 3 ≈ 14Hz


Mechanical walker

Mechanical Walker


H kazerooni human engineering laboratory hel university of california at berkeley

Ground Reaction Force Control

The only external force on a walking machine is imparted by the ground.

Considering Newtonian Mechanics, zero Ground Reaction Forces lead to zero motion (f = m α)

Large Ground Reaction Forces lead to large acceleration and large speed


H kazerooni human engineering laboratory hel university of california at berkeley

A leg during stance phase

Infinitely Rigid Ground

Ground Reaction forces = f (T1, T2)


H kazerooni human engineering laboratory hel university of california at berkeley

A leg during swing phase

A leg during swing phase does

not contribute to motion of the

machine.

Zero Stiffness Ground

Ground Reaction forces = 0


H kazerooni human engineering laboratory hel university of california at berkeley

A leg during stance phase

The fundamental method of creating locomotion for the walking machine is the generation of appropriate ground reaction forces on the machine leg that is in contact with the ground, not the leg which is swinging; in fact, the leg during the swing phase should not be powered to save energy.

Actual Ground

Ground Reaction Forces = f ( T1, T2 and K)


H kazerooni human engineering laboratory hel university of california at berkeley

The Ground Reaction Forces are the “Actuators” of a Walking Machine


H kazerooni human engineering laboratory hel university of california at berkeley

W

ηW

The Horizontal Ground Reaction

Forces are controlled to be larger than ηW


Electronic schematic

Electronic Schematic


H kazerooni human engineering laboratory hel university of california at berkeley

Inclined Maneuvers

ηW Cos () +W Sin ()

The Ground Reaction Forces must be controlled

to be larger than ηW Cos () +W Sin ()


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