Formation Control Of Nonholonomic Robots Research Articles

Self-Triggered Formation Control of Nonholonomic Robots.

In this paper, we report the design of an aperiodic remote formation controller applied to nonholonomic robots tracking nonlinear, trajectories using an external positioning sensor network. Our main objective is to reduce wireless communication with external sensors and robots while guaranteeing formation stability. Unlike most previous work in the field of aperiodic control, we design a self-triggered controller that only updates the control signal according to the variation of a Lyapunov function, without taking the measurement error into account. The controller is responsible for scheduling measurement requests to the sensor network and for computing and sending control signals to the robots. We design two triggering mechanisms: centralized, taking into account the formation state and decentralized, considering the individual state of each unit. We present a statistical analysis of simulation results, showing that our control solution significantly reduces the need for communication in comparison with periodic implementations, while preserving the desired tracking performance. To validate the proposal, we also perform experimental tests with robots remotely controlled by a mini PC through an IEEE 802.11g wireless network, in which robots pose is detected by a set of camera sensors connected to the same wireless network.

Consensus-based Formation Control of Nonholonomic Robots using a Strict Lyapunov Function

This paper presents a novel decentralized consensus-based formation controller that considers both, the kinematic and the dynamic model, to uniformly and asymptotically drive a network composed of N nonholonomic mobile robots to a desired formation with a given orientation. The network is modeled as an undirected, static and connected graph. The controller is a smooth time-varying δ—persistently exciting controller of the Proportional-Derivative type. The stability analysis is carried out using a novel strict Lyapunov function. Simulations, using a network with six agents, illustrate our theoretical contributions.

Integral terminal sliding mode formation control of non-holonomic robots using leader follower approach

SUMMARYMulti-robot formation control has become an important area of research due to its advantages and applications. This paper presents multi-robot formation control using a leader–follower approach without considering the leader's velocity information or estimation. The leader–follower formation is formulated by incorporating the model uncertainties and disturbances. A novel formation controller is presented using integral terminal sliding mode (ITSM) control, which drives the formation tracking error convergence to zero in finite-time. The stability of the close-loop control scheme is verified by using Lyapunov theory. Furthermore, obstacle detection and avoidance are incorporated to avoid collision while maintaining the formation. The effectiveness of the proposed controller is verified and validated using sine and lamniscate curve trajectories. Moreover, the performance of the proposed ITSM formation controller is compared with the standard linear sliding mode (LSM) control.

Adaptive PID formation control of nonholonomic robots without leader's velocity information

This paper proposes an adaptive proportional integral derivative (PID) algorithm to solve a formation control problem in the leader–follower framework where the leader robot's velocities are unknown for the follower robots. The main idea is first to design some proper ideal control law for the formation system to obtain a required performance, and then to propose the adaptive PID methodology to approach the ideal controller. As a result, the formation is achieved with much more enhanced robust formation performance. The stability of the closed-loop system is theoretically proved by Lyapunov method. Both numerical simulations and physical vehicle experiments are presented to verify the effectiveness of the proposed adaptive PID algorithm.

On the Topologies Conforming Singular Perturbation in Formation Control of Nonholonomic Robots

Formation control of a group of robots finds application in generating different geometric patterns and shapes, and also in locking known static or moving objects. This paper mainly explores different topologies which can be used for the formation of single group of wheeled mobile robots with nonholonomic constraints along with the existing ones. These topologies represents the connectivity constraint relationship among the robots. Each of these topologies or transformations separates the group into a reference vector (e.g. a centroid or a leader) and other shape variables, thus separating the overall dynamics into reference dynamics and shape dynamics. The gains of the controllers of these two dynamics are such chosen that the overall dynamics becomes a singularly perturbed system. Thus two dynamics converge at different time, shape vector dynamics being the faster than the reference dynamics. Negative gradient of a potential based function has been appended to the controller to ensure collision avoidance among the robots. Simulation results has been provided to demonstrate the effectiveness of the proposed controller.