Hamid Teimoori

A method for guidance and control of an autonomous vehicle in problems of border patrolling and obstacle avoidance

We present a sliding mode based method for a unicycle-like vehicle control and guidance. The proposed guidance-control law is applied to the problems of border patrolling and obstacle avoidance. A mathematically rigorous analysis of this law is provided.

Equiangular navigation and guidance of a wheeled mobile robot based on range-only measurements

We consider the problems of a wheeled mobile robot navigation and guidance towards an unknown stationary or maneuvering target using range-only measurements. We propose and study several methods for navigation and guidance termed Equiangular Navigation Guidance (ENG) laws. We give mathematically rigorous analysis of the proposed guidance laws. The performance is confirmed with computer simulations and experiments with ActivMedia Pioneer 3-DX wheeled robots.

Navigation of a unicycle-like mobile robot for environmental extremum seeking

We consider a single Dubins-like mobile robot traveling with a constant longitudinal speed in a planar region supporting an unknown field distribution. A single sensor provides the distribution value at the current robot location. We present a new sliding mode navigation strategy that drives the robot to the location where the field distribution attains its maximum. The proposed control algorithm does not employ gradient estimation and is non-demanding with respect to both computation and motion. Its mathematically rigorous analysis and justification are provided. Simulation results confirm the applicability and performance of the proposed guidance approach.

A biologically inspired method for robot navigation in a cluttered environment

The problem of wheeled mobile robot (WMR) navigation toward an unknown target in a cluttered environment has been considered. The biologically inspired navigation algorithm is the equiangular navigation guidance (ENG) law combined with a local obstacle avoidance technique. The collision avoidance technique uses a system of active sensors which provides the necessary information about obstacles in the vicinity of the robot. In order for the robot to avoid collision and bypass the enroute obstacles, the angle between the instantaneous moving direction of the robot and a reference point on the surface of the obstacle is kept constant. The performance of the navigation strategy is confirmed with computer simulations and experiments with ActivMedia Pioneer 3-DX wheeled robot.

Range-only measurements based target following for wheeled mobile robots

We consider the problem of navigation and guidance of a wheeled mobile robot towards a maneuvering target based on the measurements concerning only the distance from the robot to the target. We propose a sliding mode controller that drives the robot to the predefined distance from the target and makes the robot follow the target at this distance. Mathematically rigorous proof of convergence and stability of the proposed guidance law is presented. Simulation results confirm the applicability and performance of the proposed guidance approach.

Method for tracking of environmental level sets by a unicycle-like vehicle

We consider a single Dubins-like vehicle traveling with a constant longitudinal speed in a planar region supporting an unknown field distribution. A sensor provides the distribution value at the vehicle location. We present a new sliding mode control method for tracking environmental level sets: the vehicle is steered to the set where the distribution assumes a pre-specified value and circulates along this set afterwards. The proposed control algorithm does not employ gradient estimation and is non-demanding with respect to both computation and motion. Its mathematically rigorous justification is provided. The effectiveness of the proposed guidance law is confirmed by computer simulations.

Decentralized Navigation of Groups of Wheeled Mobile Robots With Limited Communication

In this paper, we consider a group of wheeled mobile robots, where each robot has very limited information on other robots in the group. We propose a simple bio-inspired decentralized navigation law, which guarantees that all robots will eventually move in the same direction and with the same speed.

Bearings-Only Guidance of a Unicycle-Like Vehicle Following a Moving Target With a Smaller Minimum Turning Radius

This technical note addresses the problem of following a moving target by a unicycle-like vehicle. The target may have higher maneuverability and a smaller minimum turning radius than the pursuing vehicle. The goal is to keep the unicycle-like vehicle as close as possible to the target all the time. We present a simple and constructive bearings-only guidance law and give its mathematically rigorous analysis.

Hover flight control of a small helicopter using robust backstepping and PID

In this paper, a robust control strategy applying on a small helicopter is proposed. The controller is designed using the backstepping approach based on Lyapunov function. In control design, a hierarchical inner-outer loop based structure is proposed to control the hover flight in the presence of external wind gusts. The outer loop (position control) employs robust backstepping controller to control the translational trajectory, while the inner loop (attitude control) controller is designed by means of PID controller that allow the stabilization of the attitude of a small helicopter. This new method combines the advantages of both robust backstepping and PID, particularly it is simple and easy to implement and tune in future real flight test. Finally, a computer simulation is conducted to show the hover flight control performance of the proposed controller in a gusty environment.

Robust altitude control of an unmanned autonomous helicopter using backstepping

In this paper, a nonlinear robust control technique is proposed to control heave motion for hover as well as vertically take-off/landing of an unmanned autonomous helicopter in the presence of external wind gusts. A heave motion model of a small helicopter is considered to derive the proposed controller for the purposes of capturing dynamic variations of thrust due to the external disturbances. A recursive (backstepping) design procedure is used to design the robust controller for vertical dynamics based on Lyapunov approach. To show the effectiveness of the proposed control method and its ability to cope with the external uncertainties in the vertical dynamics, results are compared with a classical PD controller. Comparative studies demonstrate that the proposed robust backstepping control method greatly enhance the performance over the classical PD controller and it is applied to RUAV hovering condition as well as vertical take-off/landing.