Integrated Structural and Controller Optimization for Lightweight Robot Design

With the development of humanoid robots,
lightweight construction and energy efficiency play an important
role. In state-of-the-art processes and methods concerning
structural optimization it is assumed that there exists a set of
external loads or load functions acting on the part. But
humanoid robots are very complex mechatronic systems. The
fact that the system's dynamic properties and its overall
behavior may change due to geometric modifications of a part
caused by an optimization process is typically neglected. In order
to take into account the interaction between the part, dynamic
system, control system and the changing mechanical behavior
with all its consequences for the optimization process, a
simulation of the complete mechatronic system is integrated into
the optimization process within the research work presented in
this paper.
A hybrid multibody system (MBS) simulation, that is, a MBS
containing flexible bodies, in conjunction with a co-simulation of
the control system represented by tools of the Computer Aided
Control Engineering (CACE) is integrated into the optimization
process. By an inner optimization loop the controller parameter
are adopted new in each iteration of the topology optimization in
order to provide realistic load cases. The research work
presented in this paper is a contribution towards the integration
of existing CAE methods into a continuous process for structural
optimization. The benefits will be illustrated by an optimization
of parts of the humanoid robot ARMAR of the collaborative
research centre for "Humanoid Robots". The new process allows
an efficient optimization of structures "within" their
surrounding mechatronic system.