  Modern Lightweight robots are constructed to be collaborative, which often
results in a low structural stiffness compared to conventional rigid robots.
Therefore, the controller must be able to handle the dynamic oscillatory effect
mainly due to the intrinsic joint elasticity. Singular perturbation theory
makes it possible to decompose the flexible joint dynamics into fast and slow
subsystems. This model separation provides additional features to incorporate
future knowledge of the jointlevel dynamical behavior within the controller
design using the Model Predictive Control (MPC) technique. In this study,
different architectures are considered that combine the method of Singular
Perturbation and MPC. For Singular Perturbation, the parameters that influence
the validity of using this technique to control a flexible-joint robot are
investigated. Furthermore, limits on the input constraints for the future
trajectory are considered with MPC. The position control performance and
robustness against external forces of each architecture are validated
experimentally for a flexible joint robot.
