Ilan Zohar

Control Strategies for Driving a Group of Nonholonomic Kinematic Mobile Robots in Formation Along a Time-Parameterized Path

This paper proposes control schemes for a group of nonholonomic kinematic mobile robots for maintaining a desired formation along a time-parameterized path. The control approach is based in particular on the flatness property and the concept of virtual vehicles. The control objective is twofold: to maintain the formation structure during motion along a desired geometric path, and to follow a timing law that dominates the rate of advancement of the group and the arrival times to assigned sites. This paper suggests, in particular, control strategies for convoy-like vehicles and for rigid formations. The leading vehicle governs the overall group motion. However, each member of the group can independently split or merge and maneuver to avoid collision (assuming that the relevant data are available by communication/sensing means) during the group motion.

Mobile robot characterized by dynamic and kinematic equations and actuator dynamics: Trajectory tracking and related application

This paper establishes control strategies for wheeled mobile robots which are subjected to nonholonomic constraints. The mobile robot model includes the kinematic and dynamic equations of motion and the actuator dynamics. Using the notion of virtual vehicle and the concept of flatness, and applying the backstepping methodology the paper proposes control schemes for trajectory tracking for the considered augmented model of the mobile robot. The resulting controller ensures exponential convergence to a desired trajectory. Applications of the tracking controller for convoy-like vehicles governed by the augmented models are considered as well. Simulation results and lab experiments are demonstrated.

Point-to-point control and trajectory tracking in wheeled mobile robots: some further results and applications

Abstract This paper extends previous results in the framework of vehicle control. In particular the paper proposes simple control schemes for driving the vehicle from a given configuration to a prescribed posture in the configuration space, for tracking a time parameterizing path, and for driving a group of vehicles in convoy. We consider the point-to-point and tracking control problems when the controller accounts for the actuator dynamics.

Controllers for trajectory tracking and string-like formation in Wheeled Mobile Robots with bounded inputs

This study presents simple controllers for achieving trajectory tracking for the kinematic model of a Wheeled Mobile Robots (WMRs) with bounded inputs. The proposed controllers are based on smooth uniformly bounded functions that can easily be realized. The underlying tracking controller can be applied to control a group of WMRs, in particular for achieving a string-like formation.

Control for teams of kinematic unicycle-like and skid-steering mobile robots with restricted inputs: Analysis and applications

In the so-called intelligent spaces it could be more effective to use multiple simpler and cheaper mobile robots instead of one complex and expensive robot. In this regard the present study develops some basic control tools for managing a team of robots in various practical tasks. In particular this study presents simple controllers for achieving trajectory tracking for a single robot and for teams of kinematic unicycle-like and skid-steering mobile robots. The control approach is based on the concepts of virtual robot and virtual team. The underlying stabilizing controllers are applied to specific situations in team control and ensures effective task accomplishment under physical constraints. In particular we are developing control strategies for establishing a convoy formation of a group of vehicles with restricted inputs. The performance of the proposed controllers are demonstrated by means of numerical and simulation results.

Path planning and optimal control strategies for unmanned aerial vehicles with bounded inputs

A simple approach has been established for solving suboptimal control problems in unmanned aerial vehicles with bounded inputs. The approach is based on trajectory parametrization for the constrained aerial vehicle control. The proposed framework for synthesizing the control algorithms employs the concept of polynomial controllability and the flatness property of the underlying physical model. In this framework the method of accomplishing the minimization is based on tools from the nonlinear dynamic programming theory, which can easily be implemented in real time computations.

Controllers for mobile robot dynamic models: Trajectory tracking with applications to convoy-like vehicles

This paper establishes control strategies for a wheeled mobile robot model that includes the kinematic and dynamic equations of motion. The vehicle model accounts also for the actuator dynamics. The paper proposes simple control schemes for tracking a time-parameterizing path. Applications of the tracking controller for convoy-like vehicles are presented. Simulation results and demonstrations of the controller performances are discussed.

Trajectory tracking and formation controls for a UAV model that incorporates dynamic effects

The paper solves the trajectory tracking control problem for unmanned aerial vehicles (UAVs) when both the kinematics and dynamics effects are intertwined in the mathematical model. Using the backstepping method we establish a controller for the considered model that ensures exponential convergence to a given reference trajectory. Then, using the concept of virtual vehicles we consider the application of the proposed controller for a group of UAVs in formation flights.

Tracking Controllers for Single and Group of Unmanned Aerial Vehicles Under Various Wind Conditions

This study presents simple controllers for trajectory tracking of the kinematic model of an Unmanned Aerial Vehicle (UAV). We consider the effects of wind perturbations on an UAV in flight, and consider the applications of an existing controller with a wind compensation term while the control objective is to track a time-varying trajectory which is given in terms of the inertial coordinate system. Application of the approach to UAVs flying in a string-like formation in the presence of additive wind perturbations is also considered. Numerical and simulation results are demonstrated.

Optimal Control Strategies for Wheeled Mobile Robot With Bounded Inputs

This paper presents a simple approach for solving optimal control problems in wheeled mobile robots with bounded inputs. The control objective is to minimize a quadratic index of performance subject to differential constraints (the mobile robot equations of motion). The solution to the problem is obtained by utilizing an explicit trajectory parametrization method, which allows us to establish a sub-optimal control strategy by minimizing a multivariable function subject to a set of algebraic constraints. The approach is based on the flatness property, which allows us to represent the flat output by a polynomial. The bounds on the input signals are taken into consideration in the current analysis.Copyright