Biologically inspired four-legged walking machine AMOS-WD02

Copyright Fraunhofer IAIS & Institute of Cognitive Science, University of Osnabrueck

AMOS-WD02 (Advanced MObility Sensor-driven Walking Device) is a simple platform for experiments with neural perception - action systems. This walking machine has 4 legs, each with 2 degrees of freedom, and one back joint referring to the morphology of salamanders. In addition, this machine has IR-sensors and auditory sensors for different reactive behaviour; e.g. obstacle avoidance and sound tropism.


Legs: Each leg has two joints (two degrees of freedom (DOF)) which are a minimum requirement to obtain the locomotion of a walking machine and which follow the basic principle of movement of a salamander leg. The upper joint of the legs, called thoracic joint, can move the leg forward and backward and the lower one, called basal joint, can move it up and down.


Body: Inspired by vertebrate morphology of the salamander’s trunk and its motion, the robot was constructed with a backbone joint which can rotate around a vertical axis. It facilitates a more flexible and faster motion. The backbone joint is also used to connect the trunk where two hind legs are attached with the head where two forelegs are installed.  

Sensors: The AMOS-WD02 has two IR sensors (called antenna-like sensors), two auditory sensors and one wireless camera.  

Modular neural control for a reactive behavior:




(For more details of the AMOS-WD02 and its controller, read the papers )



Dimension without the tail (L x B x H): 28 x 30 x 14 cm

Weight: 3.3 Kg
Structure of Polyvinyl Chloride (PVC) and Aluminum alloys AL5083
4 Legs with 2 degrees of freedom of each leg
Active tail rotating in horizontal and vertical axis
Driven by eight analog (90 Ncm), one digital (220 Ncm) and two micro
(20 Ncm) servomotors.

Backbone joint rotating in a vertical axis


Multi-Servo IO-Board (MBoard)1 developed at Fraunhofer Institute
in Sankt Augustin. It is able to control up to 32 servomotors synchronously.
At the same time 32 (+4 optional) analog input channels
can be sampled and read with an update rate of up to 50 cycles per second.
The board has an RS232 interface, which serves as the standard
communication interface.

Personal Digital Assistant (PDA) having an Intel (R) PXA255 processor
for programming neural preprocessing and control. It communicates
with the MBoard via an RS232 interface.

The support circuitry of the auditory sensors

Battery of 4.8v NiMH 2100mAh for the servomotors

Battery of 4.8v NiMH 2100mAh for the support circuitry of the auditory

Battery of 9v NiMH for the MBoard

Battery of 9v NiMH for the wireless camera

2 distance measurement infrared sensors (antenna-like sensors) located
at the forehead

2 auditory sensors located at the fore left and rear right legs

Mini wireless camera built in a microphone installed on the top of the tail


C programming on the MBoard for controlling servomotors and for
reading digitized sensor data

Embedded Visual C++ on the PDA for programming neural preprocessing
and control

Reactive behavior with modular neurocontroller:

Video clip 1 : Simulated AMOS-WD02 via the physical simulation (Yet Another Robot Simulator YARS provided by Frank Pasemann and Keyan Mahmoud
Ghazi-Zahedi from Fraunhofer AIS).

Video clip 2 : Reactive behavior of the physical autonomous walking machine AMOS-WD02

Video clip 3 : DEMO

New !!!

Video clip 4:

The reactive behavior of the four and six-legged walking machines (AMOS-WD02 and -WD06)simulated on the physical simulator YARS. The left panel shows the simulated walking machine with its virtual environment. The right panel shows the reactive neurocontroller and the activation of each neuron. (35.0 MB) avi (Extension 1)

Video clip 5: The physical walking machines (AMOS-WD02 and -WD06) and their reactive behaviors in different environmental situations. (21.0 MB) avi (Extension2)
Video clip 6:

Locomotion of AMOS-WD02 with and without the activation of its backbone joint


Manoonpong, P. Neural Preprocessing and Control of Reactive Walking Machines: Towards Versatile Artificial Perception-Action Systems (Cognitive Technologies) (Hardcover), Springer-Verlag, (published 2007, in English)

Manoonpong, P.; Pasemann, F.; Roth, H. (2007). Modular reactive neurocontrol for biologically-inspired walking machines. The International Journal of Robotics Research, vol. 26, no. 3, pp. 301-331, DOI: 10.1177/0278364906076263 (pdf) ("The final, definitive version of this paper has been published in IJRR, 3, March/2007 by Sage Publications Ltd, All rights reserved. © SAGE Publications Ltd, year of publication. It is available at: ") , (Multimedia files: Extension1, Extension2)

Manoonpong, P.; Pasemann, F.; Fischer, J.; Roth, H. (2005). Neural processing of auditory signals and modular neural control for sound tropism of walking machines. International Journal of Advanced Robotic Systems (ARS), ISSN: 1729-5506, vol. 2, no. 3, pp. 223–234. (one of the best publications of the month at Fraunhofer AIS) (pdf)

Manoonpong, P.; Pasemann, F.; Fischer, J. (2005). Modular neural control for a reactive behavior of walking machines. In: Proceedings of the Sixth IEEE Symposium on Computational Intelligence in Robotics and Automation (CIRA 2005), ISBN: 0-7803-9355-4, Helsinki University of Technology, Finland, pp. 403–408. (pdf)

Manoonpong, P.; Pasemann, F.; Fischer, J. (2004). Neural processing of auditory-tactile sensor data to perform reactive behavior of walking machines. In: Proceedings of the IEEE International Conference on Mechatronics and Robotics (MechRob ’04), Achen, Germany, ISBN: 3-938153-50-X, vol. 1, pp. 189–194. (pdf)

Manoonpong, P.; Pasemann, F. (2005). Advanced mobility sensor driven-walking device 02 (AMOS-WD02). In: Proceedings of the Third International Symposium on Adaptive Motion in Animals and Machines, Robot data sheet, Ilmenau: ISLE, ISBN: 3-938843-03-9, p. R22. (pdf)

News of AMOS-WD02