toward controlled passive actuationrobotics.estec.esa.int/.../astra2013/presentations/... ·...

Toward Controlled Passive Actuation

Douwe Dresscher

ASTRA 2013

1

What can you expect (I)

2

What can you expect (I)

20 minutes presentation (a lot of me)

2

What can you expect (I)

20 minutes presentation (a lot of me)

5 minutes of Q&A and discussion afterwards (a lot of you)

2

What can you expect (I)

20 minutes presentation (a lot of me)

5 minutes of Q&A and discussion afterwards (a lot of you)

---------------------------------------- +

2

What can you expect (I)

20 minutes presentation (a lot of me)

5 minutes of Q&A and discussion afterwards (a lot of you)

---------------------------------------- +25 minutes total

2

What can you expect (II)

3

What can you expect (II)

• Context

3

What can you expect (II)

• Context

• Problem

3

What can you expect (II)

• Context

• Problem

• Solution

3

What can you expect (II)

• Context

• Problem

• Solution

• Wrap-up

3

What can you expect (II)

• Context

• Problem

• Solution

• Wrap-up

• Questions

3

Context: the short version

4

5

RObotic SEnsors project

5

RObotic SEnsors project

6

RObotic SEnsors projectLocomotion

Rocks/stones

Loose sand

Steep slopes

Roads

Energy consumption (potential)

Environmental footprint

ESA - AOES Medialab Mattracks FZI Research Centerfor Information TechnologyImage courtesy of:

6

RObotic SEnsors projectLocomotion

Rocks/stones

Loose sand

Steep slopes

Roads

Energy consumption (potential)

Environmental footprint

ESA - AOES Medialab Mattracks FZI Research Centerfor Information TechnologyImage courtesy of:

The problem(s)(Challanges if you wish)

7

High number of actuators compared to tracked and

wheeled vehiclesActuators are heavy

Mass has to be supported by the legs

Low payload-to-weight ratio

Low energy-efficiency

Energy lost at impact scales with mass

Relatively high system mass

Impact at every step

System suffers increased mechanical

stress

AND AND

AND

Based on literature8

High number of actuators compared to tracked and

wheeled vehiclesActuators are heavy

Mass has to be supported by the legs

Low payload-to-weight ratio

Low energy-efficiency

Energy lost at impact scales with mass

Relatively high system mass

Impact at every step

System suffers increased mechanical

stress

AND AND

AND

Based on literature

“It seems unrealistic to acount the low energy efficiency to impact only”

8

Motion profile

0 1 2 3 4 5 6time {s}

-0.05

0

0.05

0.1Position setpoint {m}Velocity setpoint {m/s}

9

Energy

0 1 2 3 4 5 6time {s}

-10

0

10

20

30

40

Supplied Energy {J}Dissipated Energy {J}Stored Energy {J}

10

Energy

0 1 2 3 4 5 6time {s}

-10

0

10

20

30

40

Dissipated Energy {J} - Motor electrical resistance Dissipated Energy {J} - SoilDissipated Energy {J} - GearboxDissipated Energy {J} - Total

11

Energy

0 1 2 3 4 5 6time {s}

-10

0

10

20

30

40

Dissipated Energy {J} - Motor electrical resistance Dissipated Energy {J} - SoilDissipated Energy {J} - GearboxDissipated Energy {J} - Total

76%

11

High number of actuators compared to tracked and

wheeled vehiclesActuators are heavy

Mass has to be supported by the legs

Low payload-to-weight ratio

Low energy-efficiency

Energy lost at impact scales with mass

Relatively high system mass

Impact at every step

System suffers increased mechanical

stress

AND AND

AND

12

High number of actuators compared to tracked and

wheeled vehiclesActuators are heavy

Mass has to be supported by the legs

Low payload-to-weight ratio

Low energy-efficiency

Energy lost at impact scales with mass

Relatively high system mass

Impact at every step

System suffers increased mechanical

stress

AND AND

AND

Additional movement in the legs compared

to wheeled and tracked vehicles

Servo-motors are very energy-inefficient in start

stop behavior and providing constant torque

Significant losses in actuatorsAND AND

12

The proposed solution(How we are approaching it)

13

Ploss = (1-efficiency) * Pin

14

Ploss = (1-efficiency) * Pin

We cant do anything about that

14

Ploss = (1-efficiency) * Pin

We cant do anything about that

But we can try to do something about that

14

Ploss = (1-efficiency) * Pin

We cant do anything about that

But we can try to do something about that

Minimize the energy flow trough the actuators

14

High number of actuators compared to tracked and

wheeled vehiclesActuators are heavy

Mass has to be supported by the legs

Low payload-to-weight ratio

Additional movement in the legs compared

to wheeled and tracked vehicles

Low energy-efficiency

Servo-motors are very energy-inefficient in start

stop behavior and providing constant torque

Energy lost at impact scales with mass

Significant losses in actuators

Relatively high system mass

Impact at every step

System suffers increased mechanical

stress

AND AND

AND

AND AND

15

High number of actuators compared to tracked and

wheeled vehiclesActuators are heavy

Mass has to be supported by the legs

Low payload-to-weight ratio

Additional movement in the legs compared

to wheeled and tracked vehicles

Low energy-efficiency

Servo-motors are very energy-inefficient in start

stop behavior and providing constant torque

Energy lost at impact scales with mass

Significant losses in actuators

Relatively high system mass

Impact at every step

System suffers increased mechanical

stress

AND AND

AND

AND AND

Reduce the number and/of size of actuatorsAbsorb the impact energyPassive gravity

compensation

Minimize the energy flow trough actuators

15

High number of actuators compared to tracked and

wheeled vehiclesActuators are heavy

Mass has to be supported by the legs

Low payload-to-weight ratio

Additional movement in the legs compared

to wheeled and tracked vehicles

Low energy-efficiency

Servo-motors are very energy-inefficient in start

stop behavior and providing constant torque

Energy lost at impact scales with mass

Significant losses in actuators

Relatively high system mass

Impact at every step

System suffers increased mechanical

stress

AND AND

AND

AND AND

Reduce the number and/of size of actuatorsAbsorb the impact energyPassive gravity

compensation

Minimize the energy flow trough actuators

15

✓ ✓

✓ ✓

✓

High number of actuators compared to tracked and

wheeled vehiclesActuators are heavy

Mass has to be supported by the legs

Low payload-to-weight ratio

Additional movement in the legs compared

to wheeled and tracked vehicles

Low energy-efficiency

Servo-motors are very energy-inefficient in start

stop behavior and providing constant torque

Energy lost at impact scales with mass

Significant losses in actuators

Relatively high system mass

Impact at every step

System suffers increased mechanical

stress

AND AND

AND

AND AND

Reduce the number and/of size of actuatorsAbsorb the impact energyPassive gravity

compensation

Minimize the energy flow trough actuators

15

✓ ✓

✓ ✓

✓

What will we use to achieve this

16

Controlled passive actuation

17

Controlled passive actuation Position

-1 0 1 2 3 4 5 6

-1

0

1

2

3

Actual position {m}Position setpoint {m}

y

x

18

Controlled passive actuation

19

Controlled passive actuation

20

Controlled passive actuation

1.Actuation forces are delivered by the spring

20

Controlled passive actuation

1.Actuation forces are delivered by the spring

➡Actuators only used for reconfiguration

20

Controlled passive actuation

1.Actuation forces are delivered by the spring

➡Actuators only used for reconfiguration

➡Actuators can be (much) smaller

20

Controlled passive actuation

1.Actuation forces are delivered by the spring

➡Actuators only used for reconfiguration

➡Actuators can be (much) smaller

➡Minimal energy flow trough actuators

20

Controlled passive actuation

1.Actuation forces are delivered by the spring

➡Actuators only used for reconfiguration

➡Actuators can be (much) smaller

➡Minimal energy flow trough actuators

2.Intrinsic gravity compensation

20

Controlled passive actuation

1.Actuation forces are delivered by the spring

➡Actuators only used for reconfiguration

➡Actuators can be (much) smaller

➡Minimal energy flow trough actuators

2.Intrinsic gravity compensation

3.Enables absorbtion and re-use of impact energy

20

Impact absorption

21

22

Energy

0 0.1 0.2 0.3 0.4 0.5 0.6time {s}

0

5

10

15

Kinetic energy {J}Mass potential energy {J}Spring potential energy {J}

Forces

0 0.1 0.2 0.3 0.4 0.5 0.6time {s}

-400

-300

-200

-100

0

100

Internal force {N}

Energy

0 0.1 0.2 0.3 0.4 0.5 0.6time {s}

0

5

10

15

Kinetic energy {J}Mass potential energy {J}

Forces

0 0.1 0.2 0.3 0.4 0.5 0.6

time {s}

-40000

-30000

-20000

-10000

0

Internal Force {N}

Without impact absorption With impact absorption

23

Wrap-up

24

Thank you!

25