Autonomous Lift Trucks: The human equation

A fundamental distinction with autonomous lift trucks often gets overlooked: Autonomous lift trucks typically need some level of human oversight and help.

Even robotic lift trucks, designed to operate in full autonomous mode, have some type of performance monitoring and exception handling technology that features a human in a support role. Additionally, “dual-mode” trucks are capable of operating autonomously, but designed so a trained operator can get on the unit and make use of it for ad-hoc tasks.

For certain, greater industry uptake of autonomous lift trucks will reduce the need for human operators overall, but humans will still play a role in many deployments of autonomous lift trucks.

“Humans and autonomous vehicles are intimately linked in a variety of ways,” says Daniel Theobold, founder of autonomous lift truck provider Vecna Robotics and co-founder of industry group MassRobotics, which works on robotics interoperability. “One way to think about this tie is as a supervisor-supervisee relationship. Robots are smart, but they aren’t magic. They’re going to need some help and supervision, just like human workers need help and supervision.”

As part of its autonomous solutions, Vecna offers software for fleet insights as well as remote support and supervision services. Autonomous tech is proven, Theobold says, but it makes sense for vendors to build in remote support and exception handling mechanisms so if an unexpected issue arises, a support person can resolve matters rapidly.

“With exception handling, first of all, you have to have an autonomy system that’s smart enough to know when it needs help, and then you need to have a system that allows the robots to get help very quickly,” says Theobold.

In short, operations increasingly need autonomous lift trucks, but autonomous fleets need human support to work well. Additionally, a growing spectrum of autonomous lift truck types and use cases is emerging, some featuring dual-mode operation. For lift truck fleets that operate in full autonomous mode nearly all the time, the role of robotic lift truck supervisor may end up going to former lift truck operators.

Exception handling

Under ideal conditions such as closed aisles, perfect loads and pristine pallets, lift truck autonomy works well, but conditions are often less than ideal, leading to the need for online support and exception handling, say vendors.

“It’s all about realizing that exceptions are exceptional,” Theobold says. “You need to be able to resolve any issues rapidly to ensure safety and reliability for the fleet.”

Human support people, Theobold says, have the cognitive skills and intelligence to help robots make good, safe decisions. A “human in the loop” approach, he adds, is preferable to tuning an autonomy platform to ignore inputs that are unlikely to be hazards but have a slight chance of being an actual hazard if totally ignored by the platform. The safest bet, he adds, is having a human help resolve exceptions to keep performance on track.

“Actually, as long as the robots are getting their work done and achieving the expected throughput, customers don’t really care if the exceptions are resolved within the robots’ head, so to speak, or if they are getting help from a human,” Theobold says.

In practice, the extent of human involvement with robotic lift trucks tends to be application specific and can be influenced by how controlled the environment is, points out Jim Gaskell, director of global automation and emerging technologies for Crown Equipment, which offers autonomous lift trucks with dual-mode capabilities.

“The mix of automated and manual operation depends a great deal on the lift truck type and the application,” Gaskell says. “Some applications are designed to isolate the automated vehicles within the aisle or within specific areas of the warehouse, where manual operation is used only to handle interventions, such as product or vehicle exceptions. Other applications, such as automated transport, operate in a less structured environment so the vehicles are more likely to encounter situations that require manual intervention.”

For example, Gaskell says, a Crown “DualMode” tow tractor can transport a train of carts autonomously with high reliability the majority of the time, but for as much of 10% of the time, a trained operator might drive the vehicle for reasons including moving it around an unexpected obstacle or completing an unscheduled delivery. Other reasons might include driving the tow tractor to manual charging station, or to a maintenance area, or any location it needs to get to that is not located on its set routes.

While dual-mode trucks have flexibility, says Gaskell, in practice, autonomous operation is achievable the vast majority of the time, freeing trained operators for other tasks, while getting the most value from the autonomous fleet.

“In a typical DualMode reach truck application, the vehicle is operated manually only to navigate to a charging station or maintenance area, or to recover it from an exception that caused the vehicle to suspend automated operation,” Gaskell says. “Manual operation that involves pallet movement is avoided so that nearly 100% of its production time is spent in automated mode.”

Another human element with lift truck autonomy is that the idea manager for robotic lift trucks may often be a former lift truck operator because they have hands-on knowledge of pallet workflows.

“This new role provides a natural career path for existing lift truck operators,” observes Gaskell. “Employees who work with automatic guided vehicles must fully understand the operational and safety requirements associated with both automated and manual operation, so existing lift truck operators have a head start. Existing operators will also have a good understanding of load quality—how the pallet is stacked and loaded—which is a key contributor to a successful automation implementation.”

Growing options

At the lower-cost end of the autonomous lift truck spectrum, solutions are emerging to address the need to automate ad-hoc, lower-volume tasks.

For example, earlier this year, Vecna and Big Joe partnered to bring out an autonomous pallet jack, the Vecna CPJ. Big Joe offers its own version of the autonomous pallet jack, known as the Big Joe “BUD.”

The unit is a collaborative or “cobot” pallet jack, so called because while it can operate in full autonomous mode using Vecna’s technology, it can also be operated manually when that makes sense. Big Joe, known for conventional pallet jacks, pallet riders and other lift truck products, designed the pallet jack with autonomy in mind, building in features such as lithium power for opportunity charging, a compact form factor and a low-profile fork section that makes it easier to spear a load autonomously, says Bill Pedriana, chief marketing officer for Big Joe.

The Vecna CPJ is an autonomous pallet jack developed in partnership with Big Joe, aimed at handling load-moving tasks where a human typically determines when a task should be initiated. Big Joe’s version of this user-directed pallet mover is nicknamed “BUD.”

Overall, says Pedriana, the cobot pallet jack is designed fill an underserved need: autonomous pallet movements that are lower volume, and typically are ad-hoc tasks where the need to start the task is determined by a front-line worker. Without an autonomous pallet jack, he adds, most operations end up having workers manually operate a conventional pallet jack or pallet rider, which can consume vast amounts of labor time on “travel”—the time spent moving a load from Point A to Point B.

“There are a lot of workflows that are more happenstance in nature—the load is ready to be moved when someone determines it’s time to move it,” says Pedriana. “It could be something like a parts request for a maintenance activity on the other side of a facility, or moving a work-in-process [WIP] load from one area to another, or moving dunnage, or moving a load of empty pallets. We call it ‘user-directed automation,’ because the load needs to be moved on an on-demand basis, as determined by a worker, yet you would rather have that worker stay in place, doing higher value-added tasks.”

The missions and destination points for the autonomous pallet jack from Vecna and Big Joe can be configured in software without the need to integrate the cobot to a warehouse management system (WMS). The integrated tablet on each robot can be used to select and start missions once they are established. With robotics-as-a-service (RaaS) available for these units, Pedriana says the modest monthly fee for the cobots opens the door to the benefits lift truck autonomy to a broader range of use cases and market segments.

“Our focus with this initial unit is small to medium-sized enterprises, because it offers an approachable price point for gaining payback on these the smaller, user-directed workflows, or as a way to automate the lower velocity and more infrequent tasks at large, higher volume operations,” he says.

Shared autonomy

Third Wave Automation is another provider of autonomous lift truck solutions that believes in the value of mixed-mode autonomous trucks, supporting remote monitoring and full remote operation of its trucks. Matt Willis, head of product for Third Wave Automation, calls it a “multi-mode” approach to autonomous lift trucks under what Third Wave calls its “shared autonomy” concept.

Under this approach, Willis explains, the autonomous lift trucks can operate in autonomous mode nearly all the time, though using Third Wave’s autonomy platform, a human located in the DC could oversee many trucks and intervene if an autonomous lift truck comes up against an unexpected situation. In busy, dynamic warehouses, adds Willis, the unexpected is to be expected, so autonomous platforms should be ready to cope with that reality.

“For example, what should be done when there’s already a pallet in a location the autonomous truck is supposed to be placing another pallet into?” Willis says. “Manual operators are good at resolving issues like this, so our approach is to put a human in the loop so that if one of our autonomous forklifts comes up against a situation where there is not a clear answer to, the operator can very quickly step in and provide guidance, and over time, the autonomy system learns from that.”

For its first autonomous lift truck, a reach truck, Third Wave Automation partnered with Clark Material Handling, using one of their reach trucks as a foundation. Willis says that in most cases, the person managing the autonomous fleet would be in the same building as the trucks, but in an office setting.

“We believe that having an experienced operator remotely monitoring the fleet and managing exceptions as they occur is the next step in having humans and machines working together to complete warehouse tasks,” Willis says. “You can combine the experience of your best operators with the capabilities of an autonomous system to achieve the performance and efficiency levels you are looking for.”

Third Wave’s autonomous reach truck can be operated manually, either by getting on the truck, or with the remote-control technology, for ad-hoc tasks that may arise. However, adds Willis, lift truck autonomy gains maximum benefit by having one person support the output of multiple autonomous units.

“In effect, our system gives operators superpowers,” he says. “One operator is now able to oversee and operate multiple trucks at once, which was just not possible before with manually operated trucks.”

High density automation

While there is human interaction with autonomous lift trucks, including having workers summon automated lift trucks with call-box communication, dual-mode capability in some autonomous trucks, and fleet monitoring, the current trend with pallet moves in high-density storage areas is toward full autonomy, with direct integration to a WMS, says Martin Buena-Franco, automation products marketing manager for The Raymond Corp.

For these high-density environments, Raymond offers its Automated Transtacker, as well as its Automated Swing-Reach trucks. The systems are intended to be used in fully automated mode, taking instructions directly from a WMS to achieve maximum efficiency in very narrow aisle, high-density storage areas, explains Buena-Franco.

The Automated Transtacker, while in the aisles, can draw power from an electrical power mechanism on a rail. This translates into 20% or more pallet moves per day, Buena-Franco adds. The Automated Swing Reach truck can autonomously move from aisle to aisle, rather than needing human assistance.

“The trend in warehousing and storage is to go higher, and also to have narrower aisles to achieve greater density and space efficiency,” says Buena-Franco. “When you combine this with other industry pressures and advances in autonomous technology and software, the needle has been moving more toward full autonomy from the manufacturing or distribution center floor into very narrow aisle storage warehouses.”

The suitability of autonomous lift trucks depends on circumstances like order volume and how difficult it is for a site to find operators, says Buena-Franco. However, he adds, many two-shift or three-shift operations with very narrow aisle layouts and higher clear heights can benefit from fully autonomous trucks that can offer efficiency and accuracy gains comparable to more costly systems for automated pallet storage and retrieval.

Autonomous lift trucks designed for very narrow aisle environments, adds Buena-Franco, are best deployed integrated with a WMS. This allows for the truck to receive work orders directly from the WMS and keeps physical inventory in sync. Work orders can also be batched to further reduce travel and time for autonomous execution. “The bottom line is that a fully integrated system can potentially optimize the operation,” says Buena-Franco.