Formation Control for Underactuated Surface Vessel Networks

2020 ◽  
Author(s):  
Bo Wang ◽  
Sergey Nersesov ◽  
Hashem Ashrafiuon
Keyword(s):  
Dynamic Model ◽  
Formation Control ◽  
Sliding Mode ◽  
Nonlinear Dynamical System ◽  
Order Error ◽  
Reduced Order ◽  
Control Approach ◽  
Surface Vessels ◽  
Underactuated Surface Vessels ◽  
Error Dynamics

Abstract Developing distributed control algorithms for multi-agent systems is difficult when each agent is modeled as a nonlinear dynamical system. Moreover, the problem becomes far more complex if the agents do not have sufficient number of actuators to track any arbitrary trajectory. In this paper, we present the first fully decentralized approach to formation control for networks of underactuated surface vessels. The vessels are modeled as three degree of freedom planar rigid bodies with two actuators. Algebraic graph theory is used to model the network as a directed graph and employing a leader-follower model. We take advantage of the cascade structure of the combined nonlinear kinematic and dynamic model of surface vessels and develop a reduced-order error dynamic model using a state transformation definition. The error dynamics and consequently all system states are then stabilized using sliding mode control approach. It is shown that the stabilization of the reduced-order error dynamics guarantees uniform global asymptotic stability of the closed-loop system subject to bounded uncertainties. The proposed control method can be implemented in directed time-invariant communication networks without the availability of global position measurements for any of the vehicles participating in the network. An example of a a network of five surface vessels is simulated to verify the effective performance of the proposed control approach.

Full-state nonlinear trajectory tracking control of underactuated surface vessels

2020 ◽  
Vol 26 (15-16) ◽  
pp. 1286-1296 ◽  
Author(s):  
Karl L Fetzer ◽  
Sergey Nersesov ◽  
Hashem Ashrafiuon
Keyword(s):  
Trajectory Tracking ◽  
Sliding Mode ◽  
Trajectory Tracking Control ◽  
Control Laws ◽  
Control Approach ◽  
Surface Vessels ◽  
Modeling Uncertainties ◽  
Underactuated Surface Vessels ◽  
System States ◽  
Error Dynamics

This article presents the development, implementation, and comparison of two trajectory tracking nonlinear controllers for underactuated surface vessels. A control approach capable of stabilizing all the states of any planar vehicle is specifically adapted to surface vessels. The method relies on transformation of the six position and velocity state dynamics into a four-state error dynamics. The backstepping and sliding mode control laws are then derived for stabilization of the error dynamics and proven to stabilize all system states. Simulations are presented in the absence and presence of modeling uncertainties and unknown disturbances. An experimental setup is then described, followed by successful experimental implementation and comparison of the two controllers.

Time-Varying Formation Control for Heterogeneous Planar Underactuated Multi-Vehicle Systems

2021 ◽  
Author(s):  
Bo Wang ◽  
Sergey Nersesov ◽  
Hashem Ashrafiuon
Keyword(s):  
Formation Control ◽  
Sliding Mode ◽  
Nonholonomic Constraints ◽  
Rigid Bodies ◽  
Control Law ◽  
Time Varying ◽  
Local Motion ◽  
Order Error ◽  
Control Approach ◽  
Vehicle Networks

Abstract This paper presents a distributed control approach for time-varying formation of heterogeneous planar underactuated vehicle networks without global position measurements. All vehicles in the network are modeled as generic three degree of freedom planar rigid bodies with two control inputs, and are allowed to have non-identical dynamics. Feasible trajectories are generated for each vehicle using the nonholonomic constraints of the vehicle dynamics. By exploiting the cascaded structure of the planar vehicle model, a transformation is introduced to define the reduced order error dynamics, and then, a sliding-mode control law is proposed. Low level controller for each vehicle is derived such that it only requires relative position and local motion information of its neighbors in a given directed communication network. The proposed formation control law guarantees the uniform global asymptotic stability (UGAS) of the closed-loop system subject to bounded uncertainties and disturbances. The proposed approach can be applied to underactuated vehicle networks consisting of mobile robots, surface vessels and planar aircraft. Simulations are presented to demonstrate the effectiveness of the proposed control scheme.

Integrated Trajectory Planning and Tracking Control of Underactuated Surface Vessels

2014 ◽  
Author(s):  
Farshad Mahini ◽  
Hashem Ashrafiuon
Keyword(s):  
Tracking Control ◽  
Nonholonomic Constraint ◽  
Actuator Saturation ◽  
Sliding Mode ◽  
Equations Of Motion ◽  
Order System ◽  
Surface Vessels ◽  
Underactuated Surface Vessels ◽  
Error Dynamics ◽  
Trajectory Tracking Controller

A novel nonlinear trajectory tracking controller for underactuated unmanned surface vessels is presented. A comprehensive planar model of the vessel with two control inputs is considered such that the system is represented by the equations of motion comprised of two double integrators subject to a second-order nonholonomic constraint. Given a target trajectory, a transitional desired trajectory is generated that uniformly satisfies the nonholonomic constraint and actuator saturation constraints. The system error dynamics is then modeled using the equations of motion and the transitional desired trajectory. A finite time sliding mode control law is developed to stabilize the yaw rotation which is robust to model uncertainties and disturbances. Consequently, the resulting reduced-order system is asymptotically stabilized via the surge force. Examples are presented and demonstrate that the approach provides trajectories and tracking control inputs which are suitable for real world applications.

Trajectory Tracking of Underactuated Surface Vessels Based on Hierarchical Sliding Mode

2014 ◽  
Author(s):  
Cheng Liu ◽  
Zaojian Zou ◽  
Jianchuan Yin
Keyword(s):  
Trajectory Tracking ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Sliding Mode ◽  
Underactuated System ◽  
Sliding Mode Controller ◽  
Control Field ◽  
Surface Vessels ◽  
Underactuated Surface Vessels ◽  
Hierarchical Sliding Mode

Trajectory tracking is an importance practice in ship motion control field. It attracts more attention recently due to its difficulties. Trajectory tracking requires the ship to arrive pinpoint location at exact time. It is a underactuated system because the degrees of freedom of control inputs are fewer than the degrees of freedom that needed to be controlled. In this paper, a hierarchical sliding mode controller and a common sliding mode controller are proposed to deal with the trajectory tracking problem of underactuated surface vessels. Simulation results validate the tracking performance of the proposed controllers. The closed-loop stability is testified by the Lyapunov stability theorem.

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