Velocity Free Adaptive Fixed-Time Formation Control of AMVs

This paper investigates the fixed-time formation (FixF) control problem for second-order multi-agent systems (MASs), where each agent is subject to disturbance and the communication network is general directed. First, a FixF protocol is presented based on the backstepping technique, where the distributed cooperative variable structure control method is utilized to handle the bounded disturbances. Then, to remove the dependence of control gains on the global information, a practical adaptive FixF control is presented, where the MASs can achieve formation with a bounded error within fixed time. Finally, a numerical example is presented to validate the theoretical result.

Download Full-text

Robust fixed-time formation control for quadrotor unmanned aerial vehicles with directed topology

Transactions of the Institute of Measurement and Control ◽

10.1177/01423312211032541 ◽

2021 ◽

pp. 014233122110325

Author(s):

Shikai Shao ◽

Yuanjie Zhao ◽

Xiaojing Wu

Keyword(s):

Unmanned Aerial Vehicles ◽

Finite Time ◽

Formation Control ◽

Controller Design ◽

Initial Conditions ◽

Fixed Time ◽

Settling Time ◽

Lyapunov Theory ◽

Directed Topology ◽

Aerial Vehicles

Formation control is one of the key technologies for multiple unmanned aerial vehicles (UAVs). Compared with asymptotic or finite-time controllers, fixed-time controller can provide a guaranteed settling time, which does not depend on initial conditions and is an appealing property for controller design. Thus, robust fixed-time formation controller design for quadrotor UAVs under external disturbance and directed topology is investigated in this paper. A multi-variable super-twisting like integral sliding mode surface and a disturbance observer are respectively designed for position and attitude loops to guarantee robustness. Bi-limit homogeneity is utilized to design the whole closed-loop fixed-time controllers. By skillfully using bi-limit homogeneity technique and Lyapunov theory, the comprehensive stability of position and attitude loops is addressed. Finally, the multiple UAVs are utilized to track a pre-planned trajectory in 3D space and simulation results illustrate that the settling time can be reduced about 40% compared with finite-time controllers.

Download Full-text

Fixed-time formation tracking for multiple nonholonomic wheeled mobile robots based on distributed observer

10.21203/rs.3.rs-397622/v1 ◽

2021 ◽

Author(s):

Fenglan Sun ◽

Hao Li ◽

Wei Zhu ◽

Jürgen Kurths

Keyword(s):

Mobile Robots ◽

Formation Control ◽

Sufficient Conditions ◽

Fixed Time ◽

Settling Time ◽

Wheeled Mobile Robots ◽

Formation Tracking ◽

Communication Topology ◽

Formation Pattern ◽

Stability Method

Abstract This paper studies the distributed fixed-time formation tracking problem of multiple nonholonomic wheeled mobile robots system over directed fixed and switching topologies. Through a classical nonlinear transformation, the formation control problem is transformed into a consensus problem. New control protocols based on a distributed observer are proposed. The communication topology between multiple nonholonomic wheeled mobile robots is directed, which can reduce the energy loss of communication. Some sufficient conditions of multiple robots achieving the expected formation pattern are given. All follower robots can track the leader's trajectory, form the desired formation shape within a fixed settling time, and make the leader in the geometric center of the formation. By adopting graph theory, Lyapunov stability method and fixed time theory, one can obtain an upper bound of the settling time, and the settling time is independent of the system's initial states. Finally, two examples are presented to illustrate the potential correctness of the main results.

Download Full-text