Biologically Inspired Kinematic Synergies Enable Linear Balance Control
of a Humanoid Robot
H. Hauser, G. Neumann, A. J. Ijspeert, and W. Maass
Despite many efforts, balance control of humanoid robots in the presence of
unforeseen external or internal forces has remained an unsolved problem. The
difficulty of this problem is a consequence of the high dimensionality of the
action space of a humanoid robot, due to its large number of degrees of
freedom (joints), and of nonlinearities in its kinematic chains. Biped
biological organisms face similar difficulties, but have nevertheless solved
this problem. Experimental data reveal that many biological organisms reduce
the high dimensionality of their action space by generating movements through
linear superposition of a rather small number of stereotypical combinations
of simultaneous movements of many joints, to which we refer as kinematic
synergies in this paper. We show that by constructing two suitable nonlinear
kinematic synergies for the lower part of the body of a humanoid robot,
balance control can in fact be reduced to a linear control problem, at least
in the case of relatively slow movements. We demonstrate for a variety of
tasks that the humanoid robot HOAP-2 acquires through this approach the
capability to balance dynamically against unforeseen disturbances that may
arise from external forces or from manipulating unknown loads.
Reference: H. Hauser, G. Neumann, A. J. Ijspeert, and W. Maass.
Biologically inspired kinematic synergies enable linear balance control of a
Biological Cybernetics, 104(4-5):235-249, 2011.