Bounded Distributed Flocking Control of Nonholonomic Mobile Robots

There have been numerous studies on the problem of flocking control for multiagent systems whose simplified models are presented in terms of point-mass elements. Meanwhile, full dynamic models pose some challenging problems in addressing the flocking control problem of mobile robots due to their nonholonomic dynamic properties. Taking practical constraints into consideration, we propose a novel approach to distributed flocking control of nonholonomic mobile robots by bounded feedback. The flocking control objectives consist of velocity consensus, collision avoidance, and cohesion maintenance among mobile robots. A flocking control protocol which is based on the information of neighbor mobile robots is constructed. The theoretical analysis is conducted with the help of a Lyapunov-like function and graph theory. Simulation results are shown to demonstrate the efficacy of the proposed distributed flocking control scheme

Mobile Formation Coordination and Tracking Control for Multiple Non-holonomic Vehicles

This paper addresses forward motion control for trajectory tracking and mobile formation coordination for a group of non-holonomic vehicles on SE(2). Firstly, by constructing an intermediate attitude variable which involves vehicles' position information and desired attitude, the translational and rotational control inputs are designed in two stages to solve the trajectory tracking problem. Secondly, the coordination relationships of relative positions and headings are explored thoroughly for a group of non-holonomic vehicles to maintain a mobile formation with rigid body motion constraints. We prove that, except for the cases of parallel formation and translational straight line formation, a mobile formation with strict rigid-body motion can be achieved if and only if the ratios of linear speed to angular speed for each individual vehicle are constants. Motion properties for mobile formation with weak rigid-body motion are also demonstrated. Thereafter, based on the proposed trajectory tracking approach, a distributed mobile formation control law is designed under a directed tree graph. The performance of the proposed controllers is validated by both numerical simulations and experiments

Distributed coordinate tracking control of multiple wheeled mobile robots

In this thesis, distributed coordinate tracking control of multiple wheeled-mobile robots is studied. Control algorithms are proposed for both kinematic and dynamic models. All vehicle agents share the same mechanical structure. The communication topology is leader-follower topology and the reference signal is generated by the virtual leader. We will introduce two common kinematic models of WMR and control algorithms are proposed for both kinematic models with the aid of graph theory. Since it is more realistic that the control inputs are torques so dynamic extension is studied following by the kinematics. Torque controllers are designed with the aid of backstepping method so that the velocities of the mobile robots converge to the desired velocities. Because of the fact that in practice, the inertial parameter of WMR maybe not exactly known or even unknown, so both dynamics with and without inertial uncertainties are considered in this thesis

Robust Distributed Formation Control of UAVs with Higher-Order Dynamics

In this thesis, we introduce distributed formation control strategies to reach an intended linear formation for agents with a diverse array of dynamics. The suggested technique is distributed entirely, does not include inter-agent cooperation or a barrier of orientation, and can be applied using relative location information gained by agents in their local cooperation frames. We illustrate how the control optimized for agents with the simpler dynamic model, i.e., the dynamics of the single integrator, can be expanded to holonomic agents with higher dynamics such as quadrotors and non-holonomic agents such as unicycles and cars. Our suggested approach makes feedback saturations, unmodelled dynamics, and switches stable in the sensing topology. We also indicate that the control is relaxed as agents will travel along with a rotated and scaled control direction without disrupting the convergence to the desired formation. We can implement this observation to design a distributed strategy for preventing collisions. In simulations, we explain the suggested solution and further introduce a distributed robotic framework to experimentally validate the technique. Our experimental platform is made up of off-the-shelf devices that can be used to evaluate other multi-agent algorithms and verify them

Distributed MPC for Formation Path-Following of Multi-Vehicle Systems

The paper considers the problem of formation path-following of multiple vehicles and proposes a solution based on combining distributed model predictive control with parametrizations of the trajectories of the vehicles using polynomial splines. Introducing such parametrization leads indeed to two potential benefits: A) reducing the number of optimization variables, and b) enabling enforcing constraints on the vehicles in a computationally efficient way. Moreover, the proposed solution formulates the formation path-following problem as a distributed optimization problem that may then be solved using the alternating direction method of multipliers (ADMM). The paper then analyzes the effectiveness of the proposed method via numerical simulations with surface vehicles and differential drive robotspublishedVersio

Arbitrary Configuration Stabilization Control for Nonholonomic Vehicle with Input Saturation:a c-Nonholonomic Trajectory Approach

This paper addresses the saturated stabilization control problem for nonholonomic vehicles with a novel c-nonholonomic trajectory approach on SE(2), with applications to automatic parking. Firstly, by defining the cnonholonomic configuration, a c-nonholonomic trajectory is obtained which provides a novel approach to design stabilization controller to reach an arbitrary configuration. Secondly, a global discontinuous time-invariant feedback controller with input saturation is proposed which does not involve time signal information, and its convergence is illustrated by a Lyapunov function approach. Thereafter, the motion trajectory of the proposed controller is analyzed, and the application scenario in automatic parking with the approximate desired trajectory is demonstrated. Finally, the performance of the proposed controller is validated by both numerical simulations and experiments.</p