A New Principle for Climbing W heeled Robots: Serpentine Climbing with the  OpenW heel Platform Jean-Christophe FAUROUX, Frédéric CHAPELLE, Chedli BOUZGARROU Mechanical Engineering Research Group (LaMI) Blaise Pascal University & French Institute for Advanced Mechanics (IFMA)

Clermont-Ferrand, France

- Projet Industriel de Fin d'Etude -- Stage Master 1 -

PLAN 1. Introduction 2. Paradigms

mono-mode robots multi-modes robots slightly actuated Generic platform Explorating wheel Serpentine frontal climbing

3. Tridimensional Kinematic Validation 4. Conclusion

Steps with motion continuity Joint angles laws

- Projet Industriel de Fin d'Etude -- Stage Master 2 -

1. Introduction

2. Paradigms

3. 3D validation

4. Conclusion

Mono-mode robots Robosoft Pioneer non suspended 4x4

LAAS Hilare 1 steering axle + casters

Robosoft Robucar TT suspended 4x4

JPL Robby frame with pods

Only one mode of displacement: rolling

LAAS Adam suspended 6x6

- Projet Industriel de Fin

JPL Rocky 7 Rocker-Bogie suspension d'Etude -- Stage Master 3 -

1. Introduction

2. Paradigms

3. 3D validation

4. Conclusion

Multi-modes robots LAAS Lama Pods with inter-axle DOF Peristalsis capabilities LRP Hylos 1 & 2 4 articulated leg/wheels Univ SHERBROOKE Azimut 4 articulated legs/tracks

Two or several modes

• • • •

Rolling EPFL Octopus Peristalsis 4 tentacles / 8 wheels Crossing - Projet ....... Industriel de Fin d'Etude Balancing

-- Stage Master 4 -

1. Introduction

2. Paradigms

3. 3D validation

4. Conclusion

Slightly actuated robots Passive mobilities for reactive configuration • •

Flat / Concave / Convex / Step 4 actuated wheels

EPFL Shrimp 4 actuated wheels + 2 wheel-steering + reactive frame

=> place for generic and modular mechanical architectures, possibly close to commercial vehicles, developed from new crossing strategies

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2. Paradigms

1. Introduction

3. 3D validation

4. Conclusion

Framework: generic platform OpenWHEEL Wireless connection A Rear

CAN Bus

W 32

S 32

A

3

Control

S 31 Wheel W

I2

S 21

Suspension mechanism Saw Swing arm

Mobile

Double wishbone

A

2

Innovative suspension

Control

I1

S 11

W11

W12

Camera

S22

Control

W21

31

W22

S 12 1

n Fro

t Z X Y

Inter-axle mechanism Ia Serial Parallel Innovative mechanism mechanism mechanism

Modular assembly Canonical components slightly actuated - Projet Industriel de Fin d'Etude -- Stage Master 6 -

2. Paradigms

1. Introduction

3. 3D validation

4. Conclusion

First study on a four-wheel version

• closer to the architecture of commercial vehicles, • climbing abilities without the weight, size and energy Consumption of six-wheel robots. R0

R2 a Re

S 12

G2

G

S 21 W21

W12

S 22

r

A2

R1

W22

A1 S

Z

Y

X

W

11

G1 n Fro

t

11

Model created in a generic way to assure the internal coherence during the analyze joint motions most independently of the kinematic architecture Rotation of each axle on itself along (Gi, z) without slip of the wheels

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1. Introduction

2. Paradigms

3. 3D validation

4. Conclusion

Reconfiguration for climbing Exploring wheel

Mode 1 : Rolling Support polygon with a rectangular shape

G

Mode 2 : Climbing Exploring wheel going upward Support polygon becoming triangular

G

Support triangle a) General four-wheel robot

b) Robot with two-pod architecture

explore Explorating Wheel Paradigm put on for new support point three wheels stability for a four-wheel vehicle - Projet Industriel de Fin d'Etude -- Stage Master 8 -

2. Paradigms

1. Introduction

3. 3D validation

4. Conclusion

Stability property Wheel W 11 (front-right) Front axle steering

1)

2)

W 12

Wheel W 21 (rear-right) 3)

Wheel W 22 (rear-left) 4)

W 11 G

G

G

W 22

G

W 21 5)

Rear axle steering

Wheel W 12 (front-left)

W 11

G

6)

7)

W 12

G

8)

G

G W 21

Stable

Instable

Stable

W 22

Instable

ex: when turning to the right

Static stability during turns is ensured when the lifted wheel is inside the turn => when a wheel is to be lifted, bring another wheel as close as possible to it .

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1. Introduction

2. Paradigms

3. 3D validation

4. Conclusion

Serpentine frontal climbing of a step obstacle

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1. Introduction

2. Paradigms

3. 3D validation

4. Conclusion

3D simulation 2 axles 4 wheels 2 intermediate bars 7 revolute joints obstacles as high as the wheels 17 principal states with motion continuity (“functional motions”) Continuous series of poses : • ensuring permanent stability • no add of any supplemental roller • only one central actuator 3D validation with Adams software ⇒ determination of angle variations from the functional motions - Projet Industriel de Fin d'Etude -- Stage Master 11 -

1. Introduction

2. Paradigms

3. 3D validation

4. Conclusion

Wheel rolling angles

curves globally ascending reversing phases correspond to when vehicle goes forward self rotation of axles - Projet Industriel de Fin d'Etude -- Stage Master 12 -

1. Introduction

2. Paradigms

3. 3D validation

4. Conclusion

Inter-axle joint rotation angles Large variation of R0 (central actuator) when wheels are lifted Angle variation depends on obstacle height and axle length Should not exceed 30 to 45 ° for keeping contact on the tire tread Always lift to the maximum or possible parametrized control in function of the obstacle height - Projet Industriel de Fin d'Etude -- Stage Master 13 -

1. Introduction

2. Paradigms

3. 3D validation

4. Conclusion

Conclusion New climbing principle for a four-wheel robot • keep efficiency of wheels propulsion • ensure climbing capacities of high obstacle with one supplemental actuator Enumeration of the poses continuously ensuring stability Validation by a 3D model Determination of the joint motion in a generic way independently of the kinematic architecture Perspectives: methods for mechanical architecture synthesis of the inter-axle Applications: new frames for quads and ATV - Projet Industriel de Fin d'Etude -- Stage Master 14 -