Magnebike: Compact Magnetic Wheeled Inspection Robot with High Mobility

Motivation and goal

Inspection of complex environment with compact mobile robots

1. Wide range of inner diameters: it varies from 200mm (max. robot space envelope) up to 700mm.
2. Local abrupt inner diameter changes, up to 50mm: 90° convex or concave obstacles.
3. Complex arrangement and sequence of the obstacles: triple step or gap.
4. Any inclination can be encountered: climbing ability is required.
5. Maneuver about in narrow locations and travel on circumferential paths.

Goal: design a mobile robot able to bring inspection sensors in this specific environment

1. Locomotion concept: design a compact climbing robot with high mobility.
2. Localization strategy: find appropriate sensors (embedded) and implement localization algorithms (external computer) that provide the robot location in the closed environment.
   
3. Integration: the system has to embed low level control electronic and sensors (for the locomotion system control and localization).
   

Locomotion Concept and Robot Design

• Two wheels in a motorbike arrangement: better adaptation to the surface (flat or curved).
• Magnetic wheel unit including lateral lifter/stabilizer arms. The lifter functionality helps to pass over step obstacles. The stabilizer functionality allows to drive sideway.
• Five active DoF: front/rear wheel, front/rear lifter, steering unit.

Videos Locomotion

Older videos

Overhanging step (first locomotion tests in 2006): wmv (12M), avi (17M), mpeg2 (37M)

Climbing steps in pipe (2007): wmv (12M), avi (16M), mpeg2 (37M)

Localization and Mapping Concept

SLAM approach

• 3D scan: provides a 3D vizualisation to the user who remote controls the robot.
• Odometry: used to track the robot position between 2 consecutive 3D scans. Used as prior knowledge for the scan matching.
  
• Scan matching: determines the 3D transformation matrix between 2 consecutive 3D scans, but also to generate a 3D model of the environment.

Sensors

• 3D range finder (rotating Hokuyo-URG04LX)
• 3-axis accelerometer
  
• Wheel encoders: odometry
  
• Strain gage between wheel units: to control the wheel speeds (avoid robot deformation)
• Strain gages on lifter arms: to control the lateral stablization system
  

Algorithm: 3D scan matching

• Scan mathing using ICP (Iteravite Closest Point)
  

Publications about this work

PhD thesis

Fabien Tâche (2010) Robot Locomotion and Localization on 3D Complex Shaped Structures. ETHZ.

Journal paper

Fabien Tâche, Wolfgang Fischer, Gilles Caprari, Roland Siegwart, Roland Moser, Francesco Mondada (2009) Magnebike: A Magnetic Wheeled Robot with High Mobility for Inspecting Complex Shaped Structures. Journal of Field Robotics, 26:453–476, May 2009 [pdf (JFR), pdf (final submission)].

Fabien Tâche, François Pomerleau, Michael Bosse, Gilles Caprari, Roland Siegwart, Roland Moser (2010) 3D Localization for the Magnebike Inspection Robot. Submitted to Journal of Field Robotics (May 2010).

Peer-reviewed Proceedings

Fabien Tâche, Wolfgang Fischer, Roland Siegwart, Roland Moser, Francesco Mondada (2007) Compact Magnetic Wheeled Robot With High Mobility for Inspecting Complex Shaped Pipe Structures. In Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems, October 29 - November 2, San Diego, California, USA [pdf]

Attached video: mpeg (4M), wmv (38M, 720x576)

Fabien Tâche, Wolfgang Fischer, Roland Moser, Francesco Mondada, Roland Siegwart (2007) Adapted Magnetic Wheel Unit for Compact Robots Inspecting Complex Shaped Pipe Structures. In Proceedings of the IEEE/ASME International Conference on Advanced Intelligent Mechatronics, September 4-7, Zürich, Switzerland [pdf]

Andreas Breitenmoser, Fabien Tâche, Gilles Caprari, Roland Moser, Roland Siegwart (2010) MagneBike - Toward Multi Climbing Robots for Power Plant Inspection. In Proceedings of the International Conference on Autonomous Agents and Multiagent Systems, May 10 - 14, Toronto, Canada [pdf]

Frédéric Rochat, Patrick Schoeneich, Fabien Tâche, Francesco Mondada, Hannes Bleuler (2010) Magnetic Wheels Optimization and Application to the MagneBike Climbing Robot. In Proceedings of the International Conference on Climbing and Walking Robots, August 31 - September 3, Nagoya, Japan [pdf]

Contact

Tâche Fabien: ftache@ethz.ch

Acknowlegments and collaboration