Frequently Asked Questions

What are the types of AGV navigation systems?

The methods of AGV navigation include wire guided, inertial guided, laser guided, grid and chemical path guided. By far, the most popular methods are wire, inertial and laser guided system.

• Wire guided systems have been available since the invention of the AGV in the early 1950’s. Although variations exist, most wire guided technologies employ a series of wires embedded in a shallow slot in the floor. The slot is cut in the floor using a concrete saw. The slot is approximately 1" deep and 1/4" wide and is backfilled once the wire is installed. The wire in the floor slot carries a low voltage, milliamp strength high frequency signal. The wire guided AGVs have sensing devices under their frames to detect the wire signals and allow the AGV to steer appropriately.
• Inertial navigation systems were introduced in the early 1990’s. It is based on the use on a gyroscope onboard the AGV. Similar to gyroscopes used on airplanes, cruise missiles, etc., the gyroscope can detect minute changes in vehicle direction. Each vehicle has a CAD type map of the system layout in its memory. The vehicles steer by comparing information from the gyroscope and odometry sensors to the map and making necessary course corrections. Typically, the tracking of inertial navigation systems is +/-1" of the true path. Small markers in the floor are used periodically to maintain the tracking accuracy.
• Laser navigation systems were introduced in the early 1980’s. These systems are based on target triangulation to keep the vehicles on course. The vehicle is equipped with a rotating laser beacon mounted approximately seven feet above the floor. This beacon scans 360 degrees around the vehicle for laser targets mounted on columns, walls, etc. The reflections from these targets are measured relative to angles from the vehicle and triangulated to allow the vehicle to determine its position. This position is compared to a CAD type map stored in the vehicle’s memory. The targets are typically located 20 to 30 feet apart, on both sides of the path to provide sufficient navigation resolution. Laser navigation is supplemented by onboard vehicle odometry sensors to obtain tracking accuracy of about +/- 1".
• Grid navigation systems rely on a floor pattern to guide the AGV. This floor pattern can be a grid of magnets, wires, colored tiles, RF devices, etc. The AGVs monitor their position along the grid following a pre-established route in their onboard memory.
• Chemical path navigation systems employ an optical guidance system onboard the AGV. Typically, a chemical line is applied to the floor surface. Under normal lighting conditions the line is not visible. However, the AGV utilizes a special path illumination light under the vehicle to detect the floor line and thereby track it. This type of path is not typically used in factories or warehouses because the floor line needs to reapplied periodically depending on wear caused by other traffic.