The present invention is generally directed to material handling vehicles and, more particularly, to an automatic guided vehicle capable of varying its travel path in order to reduce wear patterns created in the floor of the material handling facility.
Material handling vehicles which are not automated may include, for example, a fork lift truck operated by a person to transport material in a facility from one location to another. Such non-automated material handling vehicles while traveling the same route do not follow an identical travel path when transporting materials, due to human error and variances between operators.
Automatic guided vehicles (AGVs) are increasingly used throughout the material handling industry in place of non-automated vehicles to transport loads. AGVs transport material along predetermined routes that are detected or sensed by the AGVs. These routes may be sensed through electromagnetic, optical, or other systems. The loads transported by the AGVs may vary in size and AGVs are particularly suited for transporting very heavy loads, such as huge steel coils along a predetermined guide path.
AGVs generally include frames for mounting the load, wheels and a guidance system. The term AGV is commonly used to refer to robust vehicle designs having any of a number of available automated guidance systems. Automatic guided carts (AGCs) is a term commonly used to refer to a vehicle used for similar but less complicated applications. Throughout this application, including the claims, the term automatic guided vehicle or AGV shall mean and include both AGV's and AGC's, as well as any other vehicle that is automatically guided.
AGVs have various designs but generally include a frame with wheels located proximate the four corners of the frame, a means of propulsion and means for directing the cart. Some AGVs include swivel castors located proximate to the corners of the frame and include a separate drive wheel assembly and rigid castors for directional control of the cart. Some AGV designs include two rigid castors fixed to the frame and located approximately midway between the swivel castors on each side of the cart frame. Other AGVs include a drive assembly that has a fixed drive wheel to propel the AGV and a steerable castor wheel to direct the movement of the AGV.
Automated guided vehicle systems include a guidance system which is commonly located on the AGV. Typical guidance systems include wire guidance, laser guidance, magnetic tape guidance, odometry guidance, inertial guidance, optical guidance, and positioning guidance such as gps. These guidance systems are typically capable of controlling AGV speed, direction, start/stop functions and, in some cases, the loading and unloading of the material and other operations at various workstations. The guidance systems may also be used to control an AGVs movement relative to other AGVs, obstacles or even people in or along the desired route.
One problem with the use of an AGV, instead of a non-automated vehicle operated by a person, arises from the repeated traveling of the same route, resulting in wear patterns in the floor of the facility where the AGV operates. Since the AGV is programmed to repeatedly follow a predetermined route, significant wear patterns develop in the floor of the facility over time. Such wear can cause floor erosion and wear patterns that may cause the AGV to inadvertently be misguided from the guide path or create difficulty in the AGV deviating from the predetermined route to avoid an obstacle. In some cases, where the load being carried by the AGV is heavy and the frequency of usage is great, these wear patterns can cause significant damage to the floor of the facility such as grooves, ruts, potholes, and pitting of the floor.