Introduction to the Locomotion of limbless modular robots Dr. Juan - - PowerPoint PPT Presentation

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Introduction to the Locomotion of limbless modular robots Dr. Juan - - PowerPoint PPT Presentation

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Introduction to the Locomotion of limbless modular robots Dr. Juan Gonzalez-Gomez School of Engineering Universidad Autonoma de Madrid Open Seminar. TAMS group. University of Hamburg. June, 17th, 2009 1 Introduction to the locomotion of snake

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School of Engineering Universidad Autonoma de Madrid

  • Dr. Juan Gonzalez-Gomez

Introduction to the Locomotion

  • f limbless modular robots

Open Seminar. TAMS group. University of Hamburg. June, 17th, 2009

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Outline

  • 1. Introduction
  • 2. Modules
  • 3. Oscillators
  • 4. Locomotion in 1D
  • 5. Locomotion in 2D
  • 6. Simulation
  • 7. Conclusions and current work

Introduction to the locomotion of snake modular robots Open Seminar. TAMS group. University of Hamburg. June, 17th, 2009

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Higher level

  • Environment perception
  • Path planning
  • Navigation
  • Making decision

Lower level

  • Coordination of the joints
  • Robot morphology
  • Gaits

Robot architecture

The Locomotion Problem (I)

  • Development of a very versatile robot with the full capability of moving on

different terrains.

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Classic approach:

  • Study the terrain
  • Design the mechanics
  • Gait realization

(Ambler, Krotkov et al, 1989)

Locomotion problem (II)

(Dante II, Bares et al, 1994)

  • NASA interested in this problem
  • Planet exploration
  • Ex. Ambler and Dante II Robots
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Locomotion problem (III)

Bio-inspired approach:

  • Copying the animals in nature

(BigDog, Raibert et al. 2008)

Boston Dynamics

(Scorpio, Dirk et al. 2007) (Aramies, Sastra. 2008)

Robotic Lab at DFKI Bremen Videos: 1,2

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Locomotion problem (IV)

(Polybot G1, Yim et al. 1997) (Polybot G2, Yim et al. 2000)

Modular self-reconfigurable approach:

  • The robots change their morphology to adapt to the terrain

Simple reconfiguration with Polybot G1. From wheel to snake Complex reconfiguration with Polybot G2. From wheel to a snake and finally to a 4-legged robot

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Modular Robotics

  • Two important aspects:
  • Robot morphology
  • Controller
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Morphology (I)

1D Topology 2D Topology 3D Topology Modular Robot classification Snakes Robots

  • Each morphology has its own locomotion capabilities
  • The number of configurations growth exponentially with the number of

modules

  • A classification is needed
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Morphology (II)

Pitch-Pitch Yaw-yaw Pitch-yaw 1D topology sub-classification (snakes robots) For studying the locomotion in 1D For studying the locomotion in 2D This robots need a special skin or passive wheels to move

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Modular robots and solid objects

  • Building solids objects using modules
  • Ej. RoomBot, (Arredondo et al.). Bioinspired Robotics Lab at EPFL
  • Self reconfigurable Furnitures with locomotion capabilities :-)
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Controllers

Calculation of the joint's angles to realize a gait: it 

  • Classic approach: Mathematical modeling
  • Calculation by inverse kinematics
  • Disadvantages: The equations are only valid for an specific morphology
  • Coordination problem:

CPG CPG CPG

  • Bio-inspired controllers: CPGs
  • Central Pattern Generators
  • CPGs control the rhythmic activities
  • Ej. The locomotion of the lamprey
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Sinusoidal oscillators

  • CPGs are replaced by a Simplified model

it=A i s in 2 T iOi

  • Sinusoidal oscillators:
  • Advantages:
  • Few resources required

CPG CPG CPG

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Outline

  • 1. Introduction
  • 2. Modules
  • 3. Oscillators
  • 4. Locomotion in 1D
  • 5. Locomotion in 2D
  • 6. Simulation
  • 7. Conclusions and current work

Introduction to the locomotion of snake modular robots Open Seminar. TAMS group. University of Hamburg. June, 17th, 2009

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First generation: Y1 modules

  • One degree of freedom
  • Easy to build
  • Cheap
  • Servo: Futaba 3003
  • Material: Plastic 3mm width
  • Size: 52x52x72mm
  • Open and “Free”
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Building the Y1 modules

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Electronics & control

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Servos E x p a n s i

  • n

p

  • r

t Power supply RS232 Connection to the PC

Electronics

  • 8-bit microcontroller (PIC16F876A from Microchip)

E x p a n s i

  • n

p

  • r

t s

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Cube-M module(I)

  • Low cost mechanical design
  • Simple robust modules assembling

manually and in a quick-to-build, easy-to- handle design

  • On-board electronics and sensors

Electronics

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Outline

  • 1. Introduction
  • 2. Modules
  • 3. Oscillators
  • 4. Locomotion in 1D
  • 5. Locomotion in 2D
  • 6. Simulation
  • 7. Conclusions and current work

Introduction to the locomotion of snake modular robots Open Seminar. TAMS group. University of Hamburg. June, 17th, 2009

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t=Asin2 T 0

  • Bending angle:
  • Sinusoidal oscillator:

The initial phase determines the bending angle in the begining.

One Oscillator (I)

The bending angle is changed following this equation: It is the angle between the two parts of the module Bending angle Amplitude

t∈[−90,90] A∈[0,90] 0∈[−180,180]

Initial phase Period Degrees Degrees Seconds Degrees

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One Oscillator (II)

Demo

Example:

  • A=45 degrees
  • 0=0
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Two oscillators (I)

1t=Asin2 T 0 2t=Asin2 T 0 

New parameter:

  • Phase difference:

∈[−180,180]

It determines the oscillation of one module relative to the other Phase difference

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=0 =180 =90

Two oscillators (II)

Demo

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Outline

  • 1. Introduction
  • 2. Modules
  • 3. Oscillators
  • 4. Locomotion in 1D
  • 5. Locomotion in 2D
  • 6. Simulation
  • 7. Conclusions and current work

Introduction to the locomotion of snake modular robots Open Seminar. TAMS group. University of Hamburg. June, 17th, 2009

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Locomotion in 1D

Is this control scheme valid? How does the oscillators parameters affect the locomotion? How many modules are needed at least to achieve locomotion? Control scheme: Questions:

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Minicube-I

  • Morphology

2 modules with a Pitch- pitch connection

  • Controller:
  • Two generators
  • Parameters:

Demo

A , ,T

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Minicube-I (I)

Oscillators and locomotion Typical values for locomotion:

  • Period --> Velocity
  • Amplitud --> Step
  • Phase difference --> Coordination

Wired model Control space

  • Two dimensions:
  • Period is a constant

A , A=40,=120

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Cube Revolutions (I)

  • Morphology:

8 modules with pitch-pitch connection

  • Controller:
  • 8 equal oscillators
  • Parameters:

Videos A , ,T

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Locomotion mechanism

x V=x T

  • Locomotion performed by the

body wave propagation

  • Step:
  • Mean Speed:
  • Serpenoid curve
  • Step calculation:

x= l k −∫0

l k c

  • s c
  • s 2k

l sds

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3 Modules caterpillar

Demo

Most effiency when:

  • A=40 degrees
  • =125
  • Application of modular robots to caterpillar-like locomotion research
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Outline

  • 1. Introduction
  • 2. Modules
  • 3. Oscillators
  • 4. Locomotion in 1D
  • 5. Locomotion in 2D
  • 6. Simulation
  • 7. Conclusions and current work

Introduction to the locomotion of snake modular robots Open Seminar. TAMS group. University of Hamburg. June, 17th, 2009

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Locomotion in 2D

Is this model feasible? How many locomotion gaits can be achieved? How many modules are needed for achieving locomotion in 2D? Control scheme: Questions: What is the relationship between the oscillators and the gaits?

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Minicube-II

  • Morphology:

3 modules with Pitch-yaw- pitch connection

  • Controller:
  • 3 oscillators
  • Parameters:

A v,A h,v,vh,T Demo

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Av=40, Ah=0

Forward

v=120 Av=Ah40 vh=90,v=0

Lateral shifting Turning

Av=40, Ah=0 Oh=30,v=120

Rotating

Av=10, Ah=40 vh=90,v=180

Rolling

Av=Ah60 vh=90,v=0

Locomotion gaits

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Hypercube (I)

  • Morphology

8 modules with pitch-yaw connection

  • Controller:
  • 4 vertical oscillators
  • 4 horizontal oscillators
  • Parameters:

A h,A v ,h,v,vh ,T Demo

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Locomotion gaits

  • Searching: Genetic algorithms
  • 5 categories of gaits
  • Characterized by the 3D body wave
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  • 3D Body wave propagation
  • Linear Step:
  • Angular Step:
  • Dimensions: width (w) x length (lx) x heigth (h)

Locomotion mechanism

 r 

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Summary of the robots

Locomotion in 1D Locomotion in 2D Snakes robots

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Cube-M module

Video

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Outline

  • 1. Introduction
  • 2. Modules
  • 3. Oscillators
  • 4. Locomotion in 1D
  • 5. Locomotion in 2D
  • 6. Simulation
  • 7. Conclusions and current work

Introduction to the locomotion of snake modular robots Open Seminar. TAMS group. University of Hamburg. June, 17th, 2009

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Software

  • 1D topology simulator (Based on Open Dynamics Engine [ODE])
  • Generics algorithms: PGAPack
  • Mathematical models in Octave/Matlab

Demo

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Outline

  • 1. Introduction
  • 2. Modules
  • 3. Oscillators
  • 4. Locomotion in 1D
  • 5. Locomotion in 2D
  • 6. Simulation
  • 7. Conclusions and current work

Introduction to the locomotion of snake modular robots Open Seminar. TAMS group. University of Hamburg. June, 17th, 2009

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The controller based on sinusoidal oscillators is valid for the locomotion of the 1D-topology modular robots

Conclusions

  • Very few resources are required for its implementation
  • The locomotion gaits are very smooth and natural
  • At least 5 different gaits can be achieved

it =Aisin 2 T iOi

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Current work

Modular grasping Locomotion of 2D Topology modular robots New module design Climbing caterpillar

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School of Engineering Universidad Autonoma de Madrid

  • Dr. Juan Gonzalez-Gomez

Introduction to the Locomotion

  • f limbless modular robots

Open Seminar. TAMS group. University of Hamburg. June, 17th, 2009