  This paper introduces an innovative observer-based modular control strategy
in a class of $n_a$-degree-of-freedom (DoF) fully-electrified heavy-duty
robotic manipulators (HDRMs) to (1) guarantee robustness in the presence of
uncertainties and disturbances, (2) address the complexities arising from
several interacting mechanisms, (3) ensure uniformly exponential stability, and
(4) enhance overall control performance. To begin with, the dynamic model of
the HDRM actuation system that exploits the synergy between cleantech
electromechanical linear actuators (EMLAs) and permanent magnet synchronous
motors (PMSMs) is investigated. In addition, the reference trajectories of each
joint are computed based on direct collocation with B-Spline curves, and
simulations on the 3-DoF HDRM are conducted to extract its key kinematic and
dynamic quantities. To guarantee the robust tracking of the computed
trajectories by the actual motion states, a novel control methodology called
robust subsystem-based adaptive (RSBA) control is enhanced through an adaptive
state observer. The RSBA control addresses inaccuracies inherent in motion
sensors, modeling errors, non-triangular uncertainties, and both torque and
voltage disturbances, to which the EMLA-driven HDRM is susceptible.
Furthermore, this approach is presented in a unified generic equation format
for all subsystems to mitigate the complexities of the entire control system.
By applying the RSBA architecture, the uniformly exponential stability of the
EMLA-driven HDRM is proved based on the Lyapunov stability theory. The proposed
control algorithm is simulated for the scrutinized mechanism, whereby its
efficacy in precisely and quickly tracking reference trajectories, alongside
the reduction of torque effort, is validated.
