Factory automation today often includes more than computerized numerical control (CNC) equipment to manufacture parts or assemble finished goods. In large factories automatically guided vehicles (AGVs) are essential for efficient and reliable transport of raw material, parts or finished goods. Also, they are statistically safer than manually operated vehicles by eliminating human error.
Manufacturing operations today require timely and efficient transportation of materials in order to maximize production while minimizing inventory. Many industries can benefit from using AGVs including those for pulp and paper, steel, food, automotive, electronics, pharmaceutical, health care and many more.
They're not limited to just industrial environments. They can be even found in hospitals to deliver goods of all types safely, efficiently and reliably 24/7. Various types of vehicles are available from tow vehicles to fork lift types and even small carts. They're made for payloads from a few pounds to many tons.
These vehicles are self contained and computer-driven with the ability to track where materials have been moved within the facility or in and out of it, and all without the need for a dedicated operator. This tracking ability adds significantly to the reliability of moving product.
A motion controller works in combination with a tracking method to precisely move along a predefined path. Navigation is typically done by an embedded wire in the floor, or an optically guided system following a reflective line painted on the factory floor. Newer guidance systems use lasers or inertial guidance systems to accommodate special situations or needs. An automation controller monitors the vehicle functions and is used for data acquisition and machine vision. This provides collision avoidance and other safety functions.
An important factor in the design of AGVs is the power train that propels the vehicle. This involves the application of electric vehicle motors and a servo drive to precisely control the speed, and steering of the vehicle. The type of motor commonly used is a permanent magnet brushless AC servomotor. These motors use high energy product magnets on the rotor and tight tolerances to produce high efficiency in a small package.
Higher efficiency relates to longer operation of the AGV before battery charging is required. Because the motors have no brushes they have very low maintenance compared to DC brush type motors and are ideal for the AGV industry. In order to operate without brushes, brushless AC motors have an integral position feedback device for the proper excitation of the windings. Because AGVs rely on their self contained batteries various charging systems are available including battery swap, automated battery swap and opportunity charging.