Laser-guided vehicles (LGVs) are used in manufacturing and distribution facilities for good reason
Compared to conventional lift trucks, laser-guided vehicles (LGVs) provide more consistent pallet throughput between manufacturing and distribution functions, less damage to racking, raw materials and merchandise, reduced labor requirements and lower cost of operation. Although recognized as a more sustainable option to lift trucks, the latest high-performance LGVs for pallet movement offer improvements in battery performance, energy utilization, vehicle uptime, CO2 reduction and enable a more integrated and space-optimized facility, making LGVs serious systems in any manufacturing or distribution facility seeking to upgrade its energy sustainability initiatives (see Figure 1).
Technology advances in automated manufacturing and distribution have enabled a more integrated approach for the operation of material handling systems, which has provided advantages for increased throughput, system uptime and a better return on investment (ROI). Along with this technological evolution, an accelerated capability for streamlined energy management, energy efficiency and sustainability also has become possible, allowing ambient temperature, deep-freeze and chilled distribution facilities to better manage their power draw, energy utilization, systems integration and operational costs.
In recent years, several material handling manufacturers have gone back to the drawing board and re-engineered many of their material handling systems from the ground up to improve energy efficiency and sustainability while maintaining these systems’ load-carrying capability.
One of these systems is LGVs. At least one manufacturer has improved the performance of lithium batteries to keep its LGVs operating on the floor longer, even in challenging deep-freeze temperatures while increasing battery life, reducing battery recharging time and energy draw.
These LGVs, operating with real-time controls, have enabled their integration with plant-wide packaging, storage and distribution functions, effectively optimizing plant footprint and throughput, thereby, enhancing sustainability initiatives.
Laser-guided vehicles (LGVs)
LGVs enable efficiencies to manufacturing and distribution. They improve production flow by bringing material to the operators, therefore, cutting cycle times, eliminating wait, walk and search time. They reduce work-in-progress (WIP) inventory. They cut labor costs by eliminating simple jobs related to material and movement. They also permit reassignment of those workers to areas where they can add more value to the facility. LGVs virtually eliminate product damage with gentle load handling and provide flexibility of process flow and throughput as needs change (see Figure 2).
LGVs provide for movement of pallets between integrated functions in manufacturing and distribution. Interfacing with multiple systems, LGVs enable reliable raw material and product handling, with near zero potential for product damage. Using a combination of logic software and wireless navigation, LGVs can perform tasks not possible with other transport systems such as the uniform movement and positioning of pallet loads to within a fraction of an inch of their designated targets, without noise and with a high degree of safety for workers and their operational environment.
LGVs evolutions
The most recent automation developments in laser-guided vehicles for pallet movement enable warehouse operators and plant production supervisors to optimize for system flexibility, modularity and scalability.
Many types of LGVs exist for use in different industries, but for many applications in manufacturing and distribution, LGVs are used for pallet movement. The four types of LGVs commonly employed are:
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Fork AGVs
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Lift-deck/unit-load AGVs
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Conveyor-deck AGVs
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Tugger AGVs.
Designed to handle various pallet types such as CHEP, EURO, blockpallet and stringer with load requirements up to 3,400 pounds, these LGVs can accommodate single-deep and double-deep racking with a telescope fork. Using a satellite remote unit, lane depth can be considerably extended (see Figure 3).
Transporting heavy pallet loads imparts huge forces on these vehicles resulting in increased maintenance and power requirements to keep LGV fleets functioning. The latest generation of LGVs incorporates design, navigation, sensor, power and controls improvements that streamline their prior operational performance.
An increasing number of supply chain manufacturers require 24-hour operation at maximum throughput in lights-out facilities. Today’s latest generation LGVs are designed to meet and exceed these requirements.
Conventional LGVs battery technology
A key factor in LGV operation and energy sustainability is battery performance. Options for battery power in LGVs are predominantly lead acid and lithium chemistries.
Lead acid batteries. The most conventional power source used in LGVs has been, and still is, lead acid. But lead is heavy, and these batteries require extensive maintenance. They are slow charging and perform poorly in extreme sub-zero temperatures.
Lithium-ion batteries. Lithium-ion batteries have changed much of this. A lithium-ion battery with the capability of putting out 140 amp-hours (Ah) of power weighs about 150 pounds. Compare this to a lead acid battery putting out the same power but weighing 700 pounds.
A lithium-ion phosphate battery recharges four times faster and delivers four times the life compared to lead acid. Typical lead acid recharge cycles max out at about 1,000, while lithium-ion phosphate is closer to 4,000 cycles. The lithium-ion phosphate battery is charging four times faster and delivering four times the life compared to lead acid.
Lithium ion is also much more operational in deep-freeze environments.
Lithium flash battery technology
Introduced for use with LGVs by E80, lithium flash battery technology, developed by Flash Battery Srl, provides a higher level of performance than other batteries for industrial vehicles. Flash battery technology uses the latest in lithium iron phosphate (LiFePO4) chemistry, which delivers low toxicity, well-defined performance and long-term stability. Having a very constant discharge voltage, flash battery technology allows the battery to deliver virtually full power until it is discharged (see Figure 4).
The cells in a lithium battery have different capacities, resistances and self-discharging potential. When one cell is 100% charged, another may be 95% charged. This difference seems small, but it can increase with each charge cycle until it becomes quite large, which lowers the battery’s charge potential and vehicle range.
To prevent loss of charge and reduce balancing and charging cycle time, flash battery electronics acts in active and passive modes to equalize the cells’ charge levels during charging and discharging. This results in 20 times faster balancing and a maximum of 30 minutes in cyclic applications, greatly reducing charge balancing and recharging times.
Supporting the performance of a facility’s fleet of LGVs and its flash battery technology, E80’s Flash Data Center continually monitors and controls every battery of the fleet integrated system. This is to ensure the LGV network keeps its battery potential in peak performance to maintain plant uptime and efficiency.
The control electronics in the lithium flash battery keeps it balanced and efficient, eliminating the need for regular maintenance. The remote monitoring system enables the condition of the battery to be determined at any time while reporting malfunctions.
Lithium flash battery technology eliminates problems connected with lead-acid batteries including high maintenance costs, low efficiency below 75%, short battery life, inability to partially charge and the cost of charging salts and exhaust vacuum systems. A single lithium flash battery is required per LGV, compared to two batteries needed with traditional lead-acid LGV applications. Lead-acid batteries will last from two to three years, compared to lithium flash battery technology, which is proposed to last eight to 10 years.
Wireless induction charging
A unique feature of lithium flash battery technology is the possibility to have wireless induction charging. The LGV approaches the charging station within 2 to 3 cm. As there is no physical contact, the risk of sparks is eliminated, resulting in safer charging operations (see Figure 5).
The LGV does not have to leave the production environment to be recharged, as the charging stations can be located within the production area. The LGV goes to a charger and within three to five minutes will recharge enough energy to operate for another two hours.
Using lithium flash battery technology on LGVs has brought performance advantages to manufacturing and distribution operations, especially in a production system that uses integrated logistics.
Reduced energy usage
The importance of reducing energy consumption and better management of energy usage becomes a more critical issue as energy costs escalate, and manufacturing and logistics operations are pressured to lower operating costs without loss of productivity. This is driving the evolution of more energy-efficient material handling systems, along with the analytic tools and controls to optimize their operation.
LGVs with lithium flash battery technology combined with wireless induction charging can deliver a considerable reduction in energy usage when compared to LGVs using lead acid batteries.
Compared to pallet conveyors, which require considerable energy to power their motors, the power requirements for LGVs using flash battery technology are up to 30% less to move the same load weight over the same distance in a manufacturing or distribution facility.
Integrated plant supports sustainability
The smooth functioning of LGVs depends on their controls system, which has the task of coordinating the orders received from the plant’s process system, warehouse management system or ERP, then directing the work for the automated guided vehicles.
But the latest generation of LGV control systems can do much more. For example, Smart Integrated Logistics (SM.I.LE80), from E80, ensures the integrated and automated management of systems and flows, communicating with production lines, palletizers and wrappers, as well as coordinating the movement of pallets in the warehouse, through to shipping. The entire logistics flow of the manufacturing and distribution environment can be centrally managed from an integrated logistics software platform that ensures the efficient integration and optimization of all operations. Such a control system also guarantees total product traceability and safety throughout the facility’s supply chain (see Figure 6).
These controls are optimized for system flexibility, modularity and scalability. The net result is better use of the facility’s footprint. Offsite storage, common in manufacturing, can now be consolidated back into the main plant, reducing vehicle travel and energy needed to power the offsite locations, particularly so in chilled and deep-freeze storage. This supports sustainability.
Control systems like SM.I.LE80 also enhance predictive maintenance, cloud-based and condition-based maintenance by providing better visibility to the operating state of every machine within the integrated environment in real time. This not only means improved system uptime but supports sustainability. More efficient operating machines make better use of energy consumption and reduce leakages of lubricants and other chemicals into the environment, particularly so with rotating equipment, which is prevalent is manufacturing and distribution facilities.
These latest high-performance LGVs for pallet movement, and their control systems, pack extreme improvements in battery performance, energy utilization and vehicle uptime. These factors make LGVs serious systems in any manufacturing or distribution facility seeking to upgrade its sustainability initiatives.
E80 S.P.A. is headquartered in Viano, Italy.
