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Model validation of a hexapod walker robot

Published online by Cambridge University Press:  17 August 2015

István Kecskés*
Doctoral School of Applied Informatics and Applied Mathematics, Obuda University, Budapest, Hungary. E-mail:,
Ervin Burkus
Doctoral School of Applied Informatics and Applied Mathematics, Obuda University, Budapest, Hungary. E-mail:,
Fülöp Bazsó
Wigner RCP, Institute for Particle and Nuclear Physics, Budapest, Hungary. E-mail: SU-Tech College of Applied Sciences, Subotica, Serbia
Péter Odry
SU-Tech College of Applied Sciences, Subotica, Serbia College of Dunaujvaros, Dunaujvaros, Hungary. E-mail:
*Corresponding author. E-mail:


Our complete dynamical simulation-model realistically describes the real low-cost hexapod walker robot Szabad(ka)-II within prescribed tolerances under nominal load conditions. This validated model is novel, described in detail, for it includes in a single study: (a) digital controllers, (b) gearheads and DC motors, (c) 3D kinematics and dynamics of 18 Degree of Freedom (DOF) structure, (d) ground contact for even ground, (e) sensors and battery model. In our model validation: (a) kinematical-, dynamical- and digital controller variables were simultaneously compared, (b) differences of measured and simulated curves were quantified and qualified, (c) unknown model parameters were estimated by comparing real measurements with simulation results and applying adequate optimization procedures. The model validation helps identifying both model's and real robot's imperfections: (a) gearlash of the joints, (b) imperfection of approximate ground contact model, (c) lack of gearhead's internal non-linear friction in the model. Modeling and model validation resulted in more stable robot which performed better than its predecessors in terms of locomotion.

Copyright © Cambridge University Press 2015 

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