Comparing Nonlinear Adaptive Motion Controllers for Marine Surface Vessels

Sørensen, Mikkel Eske Nørgaard; Breivik, Morten

doi:10.1016/j.ifacol.2015.10.295

Cited by 23 publications

(10 citation statements)

References 13 publications

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“…The design is similar to the backstepping method, which has been applied in e.g. [2], [6] and [15], but omits the coupling between the pose and velocity control loops, which results in a cascaded system. Hence, we call this approach for cascaded backstepping control design.…”

Section: Control Designmentioning

confidence: 99%

Comparing Combinations of Linear and Nonlinear Feedback Terms for Ship Motion Control

2020

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In this paper, combinations of linear and nonlinear feedback terms are investigated for 3 degrees-of-freedom pose and velocity control of ships. Nonlinear control algorithms that are found in the literature often have linear feedback terms, which result in nice globally exponential stability properties when assuming no actuator constraints. However, considering that all actuators have saturation constraints, such stability properties are not feasible in practice. Applying nonlinear feedback terms can be a step to handle such constraints. As a result, this paper explores nonlinear feedback terms for both the kinematic and kinetic control loops. Specifically, three controllers based on a cascaded backstepping control design are implemented and compared through simulations and model-scale experiments in an ocean basin. Stability properties and tuning rules for all the controllers are also provided. Interestingly, the use of nonlinear feedback terms gives the ability to constrain the feedback control inputs globally while simultaneously being able to change the convergence rates locally. The price to be paid is the introduction of additional tuning parameters. The three controller types are compared using performance metrics which consider both control accuracy and energy use. INDEX TERMS Ship motion control, Dynamic positioning, Cascaded backstepping control design, Nonlinear feedback terms, Tuning rules, Performance metrics, Experimental results.

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Section: Control Designmentioning

confidence: 99%

Comparing Combinations of Linear and Nonlinear Feedback Terms for Ship Motion Control

2020

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“…We also consider the integral of the absolute error multiplied by the energy consumption (IAEW), which was proposed earlier in [11] as…”

Section: A Performance Metricsmentioning

confidence: 99%

A ship heading and speed control concept inherently satisfying actuator constraints

Sørensen

Breivik

Eriksen

2017

2017 IEEE Conference on Control Technology and Applications (CCTA)

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Abstract-Satisfying actuator constraints is often not considered in the academic literature on the design of ship heading and speed controllers. This paper considers the use of a simplified dynamic window algorithm as a way to ensure that actuator constraints are satisfied. To accomplish this, we use the simplified dynamic window algorithm as a dynamic window-based controller (DWC) to guarantee that the velocities remain within a set of feasible boundaries, while simultaneously respecting the actuator constraints. We also develop a modified nonlinear ship model on which to test the proposed concept. The DWC is compared with a more traditional ship heading and speed controller, using performance metrics which consider both control accuracy and energy use. I. INTRODUCTIONWhen a ship sails the sea, its autopilot system usually leads the ship along the desired heading. Numerous motion controllers and autopilots have been proposed over the years. However, many control algorithms found in the literature do not consider saturation constraints for the actuators. Examples of traditional control designs for ship autopilot systems are given in [1]. Not considering actuator constraints may lead to unsatisfying performance or stability issues. In [2], a gain-scheduled control law is developed and tested for handling actuator constraints for a rudder-roll model of a ship.In [3], the dynamic window (DW) algorithm is suggested as a method to perform collision avoidance and deal with constraints imposed by limited velocities and accelerations for mobile robots. This algorithm first generates a set of possible trajectories. Based on these trajectories, a search space of possible velocities can be approximated. The acceleration constrains are considered by limiting the search space to reachable velocities within a next time interval. To reduce the search space even further, all non-admissible velocities are removed to make the vehicle stop safely before it reaches the closest obstacle on the corresponding trajectory.The DW algorithm is modified for AUVs in [4] and shows promising results for handling magnitude and rate constraints for the actuators. In this paper, we consider a simplification of the DW algorithm in [4], by removing the collision avoidance part of the algorithm. In particular, this DW-based controller (DWC) will be combined with a heading controller based on the design in [5].The contribution of this paperis the proposal of the DWC, which inherently satisfies actuator constraints. Furthermore,

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“…In [29] and [30], it is shown through system identification that these coefficients are almost perfectly identified, which gives the justification for this assumption about these coefficients. In [31], uncertainty in the control signal and external disturbances are also considered.…”

Section: Assumptionsmentioning

confidence: 99%

Performance Comparison of Controllers with Fault-Dependent Control Allocation for UAVs

Sørensen

Hansen

Breivik

et al. 2017

J Intell Robot Syst

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This paper combines fault-dependent control allocation with three different control schemes to obtain fault tolerance in the longitudinal control of unmanned aerial vehicles. The paper shows that faultdependent control allocation is able to accommodate actuator faults that would otherwise be critical and it makes a performance assessment for the different control algorithms: an L 1 adaptive backstepping controller; a robust sliding mode controller; and a standard PID controller. The actuator faults considered are the partial to total loss of the elevator, which is a critical component for the safe operation of unmanned aerial vehicles. During nominal operation, only the main actuator, namely the elevator, is active for pitch control. In the event of a partial or total loss of the elevator, faultdependent control allocation is used to redistribute control to available healthy actuators. Using simulations of a Cessna 182 aircraft model, controller performance and robustness are evaluated by metrics that assess control accuracy and energy use. System uncertainties are investigated over an envelope of pertinent variation, showing that sliding mode and L 1 adaptive backstepping provide robustness, where PID control falls short. Additionally, a key finding is that the fault-dependent

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Comparing Nonlinear Adaptive Motion Controllers for Marine Surface Vessels

Cited by 23 publications

References 13 publications

Comparing Combinations of Linear and Nonlinear Feedback Terms for Ship Motion Control

Comparing Combinations of Linear and Nonlinear Feedback Terms for Ship Motion Control

A ship heading and speed control concept inherently satisfying actuator constraints

Performance Comparison of Controllers with Fault-Dependent Control Allocation for UAVs

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