Visibility maintenance via controlled invariance for leader-follower vehicle formations

This paper studies the visibility maintenance problem (VMP) for a leaderfollower pair of Dubins-like vehicles with input constraints and proposes an original solution based on the notion of controlled invariance. The nonlinear model describing the relative dynamics of the vehicles is interpreted as a linear uncertain system, with the leader robot acting as an external disturbance. The VMP is then reformulated as a linear constrained regulation problem with additive disturbances (DLCRP). Positive D-invariance conditions for linear uncertain systems with parametric disturbance matrix are introduced and used to solve the VMP when box bounds on the state, control input and disturbance are considered. The proposed design procedure can be easily adapted to more general scenarios. Simulation results illustrate the theory and show the effectiveness of our approach

Range estimation from a moving camera: an Immersion and Invariance approach

The paper proposes an original solution to the range identification problem for perspective dynamical systems. The depth of a static point observed by a pinhole camera undergoing a predefined 3-D motion, is estimated from its 2-D projection on the image plane. The proposed nonlinear observer relies on the Immersion and Invariance (I&I) methodology and offers several advantages over the existing range estimators. The paper also provides an analytical study of nonlinear observability performed with the Extended Output Jacobian. Extensive simulation experiments illustrate the theory and show the effectiveness of the proposed design

Vision-based range estimation via Immersion and Invariance for robot formation control

The paper introduces a new vision-based range estimator based upon the Immersion and Invariance (I&I) methodology, for leader-follower formation control. The proposed reduced-order nonlinear observer achieves global exponential convergence of the observation error to zero and it is extremely simple to implement and to tune. A Lyapunov analysis is provided to show the stability of the closed-loop system arising from the combination of the range estimator and an input-state feedback controller. Simulation experiments illustrate the theory and show the effectiveness of the proposed design

On visibility maintenance via controlled invariance for leader-follower Dubins-like vehicles

The paper studies the visibility maintenance problem (VMP) for a leader-follower pair of robots modelled as first-order dynamic systems and proposes an original solution based on the notion of controlled invariance. The nonlinear model describing the relative dynamics of the vehicles is interpreted as linear uncertain system, with the leader robot acting as an external disturbance. The VMP can then be reformulated as a linear constrained regulation problem with additive disturbances (DLCRP). New positive D-invariance conditions for linear uncertain systems with parametric disturbance matrix are introduced and used to solve the VMP when box bounds on the state, control input and disturbance are considered. The proposed design procedure can be easily adapted to provide the control with UBB disturbances rejection capabilities. As an extension, the paper addresses the VMP on a circle. Simulation experiments show the effectiveness of the proposed designs

Human-Robot Formation Control via Visual and Vibrotactile Haptic Feedback

In this paper we present a new visuo-haptic interaction mechanism for human-robot formation control. The formation setup consists of a human leader and multiple follower robots. The mobile robots are equipped only with RGB-D cameras, and they should maintain a desired distance and orientation to the leader at all times. Mechanical limitations common to all the robots limit the possible trajectories that the human can take. In this regard, vibrotactile feedback provided by a haptic bracelet guides the human along trajectories that are feasible for the team by warning her/him when the formation constraints are being violated. Psychophysical tests on the bracelet together with real-world experiments conducted with a team of Pioneer robots show the effectiveness of the proposed visuo-haptic paradigm for the coordination of mixed human-robot teams

A Geometric Solution to the Cheap Spectral Factorization Problem

The paper studies the cheap spectral factorization problem in the state space from a strictly geometric viewpoint. A new solution based on the geometric properties of the related Hamiltonian system is proposed and the connection between the H2-optimal model following and the spectral factorization problems is pointed out. A numerical example illustrates the theory and shows the effectiveness of the proposed solution

Human-Robot Formation Control via Visual and Vibrotactile Haptic Feedback

In this paper we present a new visuo-haptic interaction mechanism for human-robot formation control. The formation setup consists of a human leader and multiple follower robots. The mobile robots are equipped only with RGB-D cameras, and they should maintain a desired distance and orientation to the leader at all times. Mechanical limitations common to all the robots limit the possible trajectories that the human can take. In this regard, vibrotactile feedback provided by a haptic bracelet guides the human along trajectories that are feasible for the team by warning her/him when the formation constraints are being violated. Psychophysical tests on the bracelet together with real-world experiments conducted with a team of Pioneer robots show the effectiveness of the proposed visuo-haptic paradigm for the coordination of mixed human-robot teams

A geometric solution to the cheap spectral factorization problem

The paper studies the cheap spectral factorization problem in the state space from a strictly geometric viewpoint. A new solution based on the geometric properties of the related Hamiltonian system corresponding to a standard cheap LQ, is proposed and the connection between the H2-optimal model following and the spectral factorization problems is pointed out. A numerical example illustrates the theory and shows the effectiveness of the proposed solution

Observer design via Immersion and Invariance for vision-based leader-follower formation control

The paper introduces a new vision-based range estimator for leaderfollower formation control, based upon the Immersion and Invariance (I&I) methodology. The proposed reduced-order nonlinear observer is simple to implement, easy to tune and achieves global asymptotical convergence of the observation error to zero. Observability conditions for the leaderfollower system are analytically derived by studying the singularity of the Extended Output Jacobian. The stability of the closed-loop system arising from the combination of the range estimator and an input-state feedback controller is proved by means of Lyapunov arguments. Simulation experiments illustrate the theory and show the effectiveness of the proposed designs