The civilian applications of AGV include mineral exploration, precision farming, intelligent transportation and others. In precision farming, the AGV are used to identify rows in the field to aid in navigation for sowing and harvesting. The G3 (GNSS/ GPRS/ GIS) based Automatic Vehicle Location (AVL) systems in transport use automatic guidance/ navigation in real time for improved performance.

The enhanced capabilities and reliability of Automatic Guided Vehicles (AGV) have expanded their acceptance in many applications/ operations without direct human intervention. While, the AGV in industrial applications are secured to the floor or to the ceiling during in-door navigation using the fixed path, the use of AGV in out-door navigation using the open path navigation is a relatively recent development. Unlike the vessels in water and air, where they navigate comparatively freely without being constrained, the vehicles on a ground may face many obstacles. The movement of AGV requires support of sensors for safe navigation by avoiding the obstacles. However, the sensors embedded with the AGV can identify obstacles in a limited area and cannot plan routes for long distances. Global Navigation Satellite Systems (GNSS), Terrain Databases and Geographical Information Systems (GIS) help to overcome this limitation during out-door operation. These technologies have direct impact on vehicle mobility in battlefields and elsewhere. They allow examining least-cost paths for planning and providing guidance in autonomous vehicle navigation.

GNSS refer to satellite based navigation systems meant to simplify navigation and tracking in unknown areas. They use satellites and ground tracking systems in conjunction with a user receiver to determine and communicate their position precisely in longitude, latitude and altitude at any moment. The vehicle can define optimal route (way points) by picking up the current position using GNSS receiver and inserting destination location. It can redefine the route by suitably defining the geo-fence (obstructions en-route, say streams, road blocks, etc.).

AGV during outdoor operations shall have access to terrain databases to make decisions using GIS. The terrain databases include the spatial layers such as topography, hydrography, land use/ land cover, soils, roads, and cultural features. Stereo imagery using remote sensing can be used to compute digital elevation model (DEM) and attach elevation data to various features contained within the area. The combination of remote sensing, digital ortho-photography and LIDAR (Light Detection and Ranging) allows delineating and updating the roads and water bodies. Local obstacles can be determined by a CCD camera and multi-spectral laser scanner tied to AGV. As obstacles are found, rerouting can take place by using the vehicle’s current position using GNSS and locating a new optimal path to the target using GIS.

The local terrain data can also be gathered by the sensors including GNSS receivers and Ground Penetrating Radars (GPR). The same can be geometrically corrected (georeferenced) using standard digital topographic maps from Survey of India (SOI). Each new data can be overlaid on top of the existing data for comparison among the two datasets. Accordingly, the existing topographic maps from SOI can be updated with the most recent data.

The spatial layers need to be suitably weighted and ranked within GIS for routing purposes. The obstacles (forests, streams and steep mountains) in the operations represent absolute barriers and are assigned zero weight. They limit the possible alternatives under consideration for defining the optimal route. The other spatial layers (such as slopes and roads) are appropriately weighted and ranked to calculate least-cost path. Different slopes can have different weights based on operating capacity of the vehicle and provide realistic routes. The ranks enhance or limit selection of route from suitability, but never restrict or assure suitability. The spatial analysis allows generation of many routes which are tested in the field for the appropriate selection of weights. Ultimately, an optimal path can be selected along with the waypoints for the AGV to follow during outdoor operations.

For defining an optimal route (Going Map) through the complex terrain, it is necessary to have quality elevation data and land use/ land cover information including vegetation cover, soil moisture, road type etc. They help to define the trafficability and enhance performance of vehicles.

The other challenges for navigation of AGV in outdoor operations include the development of knowledge base along with decision rules and policies using even fuzzy algebra.

The paper will cover basics of GIS along with defining the least-cost paths/ going maps with application in navigation of AGV.

REFERENCES

Kaushal A., 2006. Shaping the Modern Day Battlefield Using Geomatics Technologies, National Seminar on Defence in Communication ‘Communication in Tactical Battle Area’, DEFCOM India 2006, April 2006, New Delhi

Kaushal A., 2006. GNSS for Intelligent Fleet Management, Location, Issue 01, Volume 02, MAY - JUNE 2006. (www.location.net.in/magazine/2006/may-jun/36_1.htm)

Kaushal A., 2006. Role of Technology in Spearheading LBS, 2nd Annual International Conference and Exhibition on Positioning, Navigation and Timing, Location 2006, June 7-9, Bangalore