Melanie v2.0 
Robust hexapod robot of 3 dof/leg for rough terrain.

By Alejandro Alonso-Puig
April 2.004
mundobot.com


Winner
HISPABOT 2004

 

Melanie is an hexapod robot of 3 degrees of freedom by leg, that by the novel design of legs which it has, can transport several kilograms on its body without excessive power overload. The tests in laboratory have shown their capacity to rise and to walk at least with 4'5kg of additional charge, twice its own weight.

The version 2.0 that is showed in this technical report is an evolution of Melanie v1.0, to which some interesting capacities have been added, like the direct programming, the generation of movements by
displacement of waves combined with inverse kinematics, or the capacity to walk on rough terrain.

Some basic characteristics that define Melanie v2.0 are the following:

Mechanics

  • Size (cm): 33 x 31 x 20
  • Weight: 2.1 Kg
  • Structure of PVC and Aluminum
  • 6 Legs. 3 degrees of freedom by leg.
  • Design of legs optimized to diminish consumption and to maximize power 
  • Driven by radio control servos (Twelve of 3kgcm and six of 5kgcm)

Electronics

  • Servos control circuit with speed management, controlled via serial port.
  • I/O circuit, with 28 A/D conversion ports and 8 digital I/O. All chips are controlled via I2C bus. Measurement of the position of the 18 servos taking the signal of their potentiometers. Measurement of the consumption of energy of the servos by measuring the voltage drop in resistances of ˝ ohm. 
  • Battery of 6v NiMH 3300mAh for the servos
  • Battery of 9v NiCd for the control electronics
  • Distance measurement infrared sensor located at the front and able to be oriented

Programming

  • Control program in PC developed in Visual C++ 6.0
  • Movement sequence recording via direct programming
  • Movements generation by displacement of three simultaneous waves and use of inverse kinematics algorithms.
  • Detection of obstacles on the ground by detection of the variation in the current consumption and adaptation of the legs and trajectories to resolve it.

In this work there will be mention to all the mechanical, electronic and programming aspects, as well as conclusions of the experience.

VIDEOS OF MELANIE 2.0

Melanie walking with 4kg over its body (MPEG 7Mb) Melanie walking over rough terrain 
(MPEG 7Mb)

 


BIBLIOGRAPHY and LINKS

Agricultural Entomology. Daniel G. Pesante Armstrong. Chapter 7: http://www.uprm.edu/wciag/anscience/dpesante/4008/cap-7.PDF
Puchobot. Quadruped Robot. Andrés Prieto Moreno: http://www.iearobotics.com/personal/andres/proyectos/pucho/pucho.html
Cube Reloaded. Worm robot. Juan González http://www.iearobotics.com/personal/juan/doctorado/cube-reloaded/
Direct & inverse kinematics course (Univ.Guadalajara-Mexico): http://proton.ucting.udg.mx/materias/robotica/r166/r78/r78.htm
Legs. General design considerations: http://www.frasco.demon.co.uk/rodney/mechan/design.htm
The Walking Machines Catalogue: http://www.walking-machines.org/
Silo4. Quadruped Robot developed by CSIC. Spain: http://www.iai.csic.es/users/silo4/
An introduction to robot kinematics: http://www.generalrobotics.org/ppp/Kinematics_final.ppt 
MSCC20. credit card-sized control computers for driving up to 20 R/C servos. Oricom Technologies: http://www.oricomtech.com/svo-cc.htm 
CSerialPort v1.03 - Serial Port Wrapper. PJ Naugter:
http://www.codeproject.com/system/cserialport.asp