Navigation Basics. The Global Positioning System. Augmentation Systems. GALILEO. GPS Modernization towards GPS III. Legal and Market Policy of Satellite Navigation. Layer Issues. Integration with Existing and Future Systems. Open Issues and Perspectives.

http://document.persiangig.com/Applied%20Satellite%20Navigation%20Using%20GPS,%20GALILEO,%20and%20Augmentation%20Systems,Ramjee%20Prasad,%20Marina%20Ruggieri___CbV9JdvZI2PH.pdf

Applied Satellite Navigation Using GPS, GALILEO, and Augmentation Systems

Most wheeled mobile robot (WMR) controllers have been developed based on nonskidding and nonslipping assumptions. Unfortunately, wheel skidding and slipping are inevitable due to wheel tire-deformation; consequently, the stability and performance of these controllers are not guaranteed. This brief aims to develop a global positioning system (GPS)-based path following a controller for a car-like wheeled mobile robot in the presence of wheel skidding and slipping. The proposed control scheme uses real-time kinematic (RTK)-GPS and other aiding sensors to measure the WMR's posture, velocities, and perturbations due to wheel skidding and slipping. These measurements are applied to compensate the path following errors based on a backstepping controller. The reported experimental results validate the control scheme. With this solution, the WMR is able to maneuver with better precision in outdoor environments in the presence of wheel skidding and slipping.

GPS-Based Path Following Control for a Car-Like Wheeled Mobile Robot With Skidding and Slipping

Many wheeled mobile robot (WMR) controllers are developed based on nonskidding and nonslipping assumptions; however, these assumptions are usually violated due to wheel tire deformation. As a result, the performance of these controllers is not guaranteed. This paper presents a GPS-based tracking controller for a car-like WMR in the presence of wheel skidding and slipping. The controller exploits real-time kinematic (RTK)-GPS and other aiding sensors to measure the WMR's posture, velocities, and perturbations due to wheel skidding and slipping for control compensation. The reported experimental results validate the control scheme.

GPS-Based Tracking Control for a Car-Like Wheeled Mobile Robot With Skidding and Slipping

In this paper, we explore the surveillance of multiple waypoints by a constant velocity aircraft in the presence of wind. It is assumed that the aircraft has a maximum turning rate and that the wind is equal to a known constant plus small possibly time varying components. The proposed strategy consists of separate path planning and control algorithms. The path planning is done by calculating the shortest time path through all of the waypoints in the presence of a known constant wind. During this step, the allowed turning rate is assumed to be less than the actual maximum turning rate of the vehicle. This algorithm produces a ground path that can be tracked by the control algorithm. The control algorithm breaks the desired trajectory into smaller sections which can each be approximated by a polynomial. A spatial sliding surface controller is then used to track each polynomial in the presence of the unknown wind disturbances.

Path planning and control for multiple point surveillance by an unmanned aircraft in wind

This paper presents a scheme for high-update rate wheel mobile robot (WMR) posture, velocities, and perturbation estimation using real-time kinematic global positioning system (RTK-GPS) and inertial sensors for WMR control in the presence of wheel skidding and slipping. An outdoor estimation system based on Kalman filtering combines the inertial measurements with centimeter accuracy RTK-GPS measurements to provide essential posture, velocities, and perturbation information. The particular contribution of this paper is in designing an estimation system to be able to deal with WMR control problems in the presence of wheel skidding and slipping. The experimental results suggest that with careful modelling of WMR, the estimation scheme is able to provide reliable and high update rate information for WMR control applications in the presence of wheel skidding and slipping.

/pdf/integrated-estimation-for-wheeled-mobile-robot-posture-2a67wkzjzk.pdf

Integrated Estimation for Wheeled Mobile Robot posture, velocities, and wheel skidding perturbations

Since Global Navigation Satellite systems are able to supply very accurate coordinates of a point (about 2 cm with a RTK GPS), such a sensor is very suitable to design vehicle guidance system. It is especially the case in agricultural tasks where a centimeter precision is often required (seeding, spraying,...). To answer to growing high precision agriculture principle demand, several control laws for automated vehicle guidance relying on this sensor have been developed. Such guidance systems are able to supply an acceptable steering accuracy as long as vehicle does not slide (path tracking on even ground with good adherence properties...), what alas inevitably occurs in agricultural tasks. Several principles are here presented to steer vehicle whatever properties of ground and path to be followed are. In this paper a new extended kinematic model with sliding accounted is presented which allows describing vehicle dynamics in all guidance conditions. Via this model a new nonlinear control law can be designed, which integrates sliding effects. Its capabilities are investigated through simulations and experimental tests.

/pdf/a-new-nonlinear-control-for-vehicle-in-sliding-conditions-1yyt7c8pt1.pdf

P. Martiner

Papers

A new nonlinear control for vehicle in sliding conditions: application to automatic guidance of farm vehicles using RTK GPS