Nonlinear coordination control of offshore boom cranes with bounded control inputs

Abstract

Offshore cranes are complicated underactuated systems, which work in harsh sea conditions. Due to the various severe disturbances, the control of offshore cranes has always been a great challenge, which is made even more complicated when considering some practical issues such as actuator saturation and coordination. Until now, few results have been published in the literature on this topic. To address this problem, an efficient nonlinear control method is proposed for offshore boom cranes suffering from both ship roll and heave motion in this paper, which takes full consideration of actuator saturation, as well as the coordination problem between actuators. Furthermore, regarding the various extra nonvanishing disturbances, such as winds, frictions, and unmodeled dynamics, a disturbance observer is designed to estimate and eliminate these uncertainties. The asymptotic stability of the desired equilibrium point is rigorously guaranteed by Lyapunov techniques and LaSalle's invariance theorem. Finally, extensive hardware experimental tests are carried out to demonstrate the feasibility and efficiency of the proposed method. To the best of our knowledge, this paper proposes the first method that considers the saturation and coordination problem for offshore cranes while guaranteeing the asymptotic stability of the desired equilibrium point.

Disturbance observer‐based robust motor control enhanced by adaptive neural network in the absence of velocity measurement

“…To be specific, the friction dynamics is very complicated, and it is affected by many different mechanisms, such as the contact geometry, the surface materials of the bodies, the presence of the lubrication, as well as the displacement and the relative velocity of the bodies 1 . In particular, the discontinuous and fast time‐varying friction dynamics around the zero velocities can generate the undesirable stick‐slip, flat peak and limit cycle 2‐7 . In theory, the friction can be approximately described by a function in terms of the velocity.…”

“…1 In particular, the discontinuous and fast time-varying friction dynamics around the zero velocities can generate the undesirable stick-slip, flat peak and limit cycle. [2][3][4][5][6][7] In theory, the friction can be approximately described by a function in terms of the velocity. Therefore, the online compensation is extremely difficult in the absence of velocity measurement, which is a common situation in practice for cost saving and weight reduction.…”

Adaptive fuzzy backstepping control of underactuated multi-cable parallel suspension system with tension constraint

“…CDPRs use an elastic cable instead of rigid legs to control the moving platform tracking desired movement (Zake et al, 2019), where the moving platform’s posture of the CDPRs is controlled by changing cable length. Since this kind of mechanical structure has many unique properties, such as huge workspace (Pusey et al, 2004), high mobility (Wang et al, 1998), and outstanding dynamic capacities (Renda et al, 2014), and so forth, and it is widely and successfully applied for offshore cranes (Lu et al, 2018), mineral lifting (Kaczmarczyk and Ostachowicz, 2003a, 2003b), and National Institute of Standards and Technology (NIST) robot (Oh and Agrawal, 2005), which is made up of two categories: fully controlled robot and underactuated controlled robot (Behzadipour and Khajepour, 2006).…”

Robust Coordinated Tracking Control of Multiple Robots System Under Bounded Inputs

“…Motivated by (Lu et al, 2019) and (Li et al, 2019), a robust hierarchical NSB+IRPD-SMC controller is proposed herein. In comparison with the current existing control algorithms, this paper has made the following contributions.…”