Autonomous mobile robots (AMRs) are used in many industries in a growing variety of logistics applications. Unlike fixed material transport systems like conveyors, AMRs can drive around a facility unlimited by a fixed route. Their wireless communications and onboard navigation systems enable them to receive commands on where to go next. AMRs can navigate to the requested location without being programmed and can even find an alternate path if an obstacle is encountered. AMRs can make warehouse operations, manufacturing processes, and workflows more efficient and productive by performing non-value-added tasks, such as transporting, picking up, and dropping off materials, to free up people to perform complex tasks that add value. Although it’s a relatively young technology, AMRs have already branched off into many distinct varieties, each of which is optimized to perform a specific type of task.
This article compares and contrasts traditional mobility solutions such as conveyor systems and automated guided vehicles (AGVs) with AMRs. It looks at the benefits of using AMRs and how the proliferation of AMR designs is expanding their utility. It discusses software integration of fleets of AMRs with other systems, including precision navigation capabilities, the potential impact of AMRs on worker safety, and how to manage and simulate fleets of AMRs. Finally, this article briefly considers how routine maintenance can maximize AMR lifespan, identify potential problems before they result in unscheduled downtime, and help proactively schedule repairs and part substitutions based on scheduled shutdowns and other operational considerations.
AGVs can deliver material to a specific location with more flexibility than a conveyor system but are much less flexible than AMRs. Like conveyors, AGVs have a fixed route. But with AGVs, the route can be more easily and quickly modified than conveyor systems. AMRs can work collaboratively with people, offer much greater flexibility, and find the most efficient route to accomplish a specific task. If an AMR encounters an obstacle, it can change its course accordingly and continue to its destination. If an AGV encounters an obstacle, it stops and requires assistance before continuing along its preassigned track (Figure 1). AMRs use a combination of onboard and centralized computing power and sophisticated sensors to interpret their environment and navigate around both fixed obstacles such as racks and workstations and variable obstacles such as forklifts, people, AGVs, and other AMRs.
Figure 1: When an AMR approaches an obstacle (left), it can independently navigate around it. When an AGV approaches an obstacle (right), it stops until help arrives. (Image source: Omron)
The Integration Toolkit (ITK) is Omron’s interface that enables centralized integration between the AMRs and client application software such as a manufacturing execution system (MES) or a warehouse management system (WMS). For example, AMRs can be integrated with the warehouse’s control systems in a warehouse and distribution center environment, giving the AMRs increased flexibility to create their routes between locations within a facility. The result is a robot that is much better able to work with humans within the dynamic environments of most order fulfillment and warehouse operations.
An AMR can also work like an AGV
Some AMR applications such as material deliveries to conveyors, feeders, and testing stands need the robot to stop at a specific location with high accuracy and repeatability. Fleet managers using Omron AMRs can select from two high-accuracy positioning systems; cell alignment position system (CAPS) and high accuracy positioning system (HAPS). CAPS or HAPS can improve goal arrival precision from about ±100 mm to ±8 mm. The main safety scanning laser on the front of the AMR is used by CAPS technology to detect a target location and enables the AMR to move to the location with high accuracy.
HAPS technology also can consistently move through a defined space with enhanced precision and/or precisely stop at a predefined goal, but with a twist. Using HAPS, the AMR can follow magnetic tape (mag tape) on the floor to navigate to a goal, similar to an AGV. A HAPS sensor underneath the AMR is used to smoothly transition from fully autonomous mode to the path defined by the mag tape. The AMR then uses a combination of onboard sensors and floor markers to precisely navigate and stop at specific locations (Figure 2).
Figure 2: Omron CAPS (left) uses the AMR’s front scanning laser combined with autonomous navigation to locate and move to a target location with high precision. HAPS (right) uses a combination of markers such as magnetic tape and onboard sensors to navigate to and stop at specific areas. (Image source: Omron)
When operating in HAPS mode, an Omron AMR can enter and leave a mag tape path at any point. That enables the AMR to smoothly transition from natural feature and autonomous navigation to AGV-like mag tape guidance. If it’s outfitted with front and rear HAPS sensors, the AMR can accurately move backward and forward along the mag tape path.
The Omron AMR system can be customized by developers, integrators, and end-users for various payloads and tasks (Figure 3). In addition to the facility integration possibilities supported by ITK, the combination of CAPS and HAPS increases the capability of these AMRs when accurate and repeatable positioning is needed and is opening up new applications such as:
- Delivery of carts full of materials
- Inventory inspection in retail stores
- Secure courier robots to deliver items to hotel guests or high-value components to workstations
- Disinfection of public spaces
- Custom collaborative AMRs
- Conveyor tops
- Delivery of heavy objects up to 1,500 kg
Figure 3: AMRs are available in various configurations optimized to perform specific tasks. (Image source: Omron)
Safe operation is mandatory for AMRs. Examples of standard safety sensors include rear sonar and front lasers for obstacle detection, a front bumper sensor to stop the AMR if it contacts an object, and light disks to alert people in the vicinity that the AMR is operating (Figure 4). Optional sensors can be added for specific requirements, such as identifying protruding or hanging obstructions. AMRs are required to comply with various national and international safety regulations such as EN 1525 (Safety of Industrial Trucks, Driverless Trucks and Their Systems), ANSI 56.5:2012 (Safety Standard for Driverless, Automatic Guided Industrial Vehicles and Automated Functions of Manned Industrial Vehicles), and JIS D 6802:1997 (Automated Guided Vehicle Systems – General Rules on Safety).
Figure 4: Omron AMRs comply with ISO EN1525, JIS D6802, and ANSI B56.5 safety standards, have multiple standard sensors dedicated to safety and can be outfitted with optional sensors for enhanced safety in specific application scenarios. (Image source: Omron)
System-level safety assessments
Meeting various national and international standards is only the start of AMR safety. AMRs are an evolving technology. They are getting more complex and handling heavier payloads creating new safety challenges. To address the evolving safety concerns with AMRs, Omron offers a safety consulting service that provides design assistance, risk assessment, testing, and validation of AMR deployments. For example, the new ISO 3691-4 standard includes specific requirements for clearance between mobile robots and other structures. Support provided by Omron Safety Service consultants includes:
- Layout design review and zones identification as required by ISO 3691-4
- Design calculations, especially in applications with high traffic or where heavy loads are being moved
- On-site solution testing and validation
AMR fleet manager
It’s almost unheard of to deploy a single AMR. Fleets of 100 AMRs are common, and Omron has an AMR management solution that provides built-in data capture, analytics, and reporting to enable organizations to optimize the performance of the overall facility operation as well as the resident robot fleet. The Enterprise Manager 2100 network appliance is a hardware and software solution designed to manage a fleet of AMRs (Image 5). Queuing management software is used to communicate with the individual AMRs; it assigns tasks to each AMR based on job requests from users or automated equipment.
Figure 5. Omron 2100 Enterprise Manager network appliance is designed to manage fleets of up to 100 AMRs. (Image source: Omron)
The Omron Fleet Operations Workspace (FLOW) solution runs on the Enterprise Manager 2100 and provides an intelligent fleet management system that monitors mobile robot locations and traffic flow. The Enterprise Manager 2100 enables users to manage and update AMR configurations. It coordinates the interaction and movement of AMRs, so each robot knows the location and path of any AMR in its vicinity. By automating various robot management tasks, FLOW software reduces programming demands on manufacturing execution systems (MES) and enterprise resource planning (ERP) systems. Features of FLOW include:
- Fleet integration toolkit based on industry standards including Restful, SQL, Rabbit MQ, and ARCL
- Prioritization of tasks based on level of importance
- Identification and selection of the fastest routes based on human and robot traffic
- Identification of blocked paths and assignment to alternative routes
- Optimization of AMR job assignments
- Optimization of battery charging schedules to maximize fleet uptime
Simulation can optimize fleets of AMRs
Even before the EM2100 network appliance is deployed for fleet management, Fleet Simulator software enables users to plan traffic and workflows for fleets of autonomous mobile robots and helps identify and solve possible problems. AMR localization, path planning, obstacle avoidance, task simulation, and fleet management based on a map of the actual facility can be accurately modeled using Omron’s Fleet Simulator. In addition, the simulations can be used to optimize the composition of the AMR fleet and predict throughput. An EM2100 can be configured as a Fleet Simulator at the factory or with a software update in the field.
Figure 6: Omron fleet simulator runs on the 2100 Enterprise Manager network appliance and can optimize an entire fleet of heterogenous AMRs before deployment. (Image source: Omron)
Once in the field, AMRs are expected to operate almost continuously, and preventative maintenance can be a crucial element in successful deployments. To support that need, Omron offers Wellness Visits that include regular in-facility evaluations of the condition of individual AMRs, enabling maintenance to be scheduled in advance, minimizing costly downtime. Benefits of Wellness Visits include:
- Maximization of AMR operating life
- Maintenance of peak AMR operating efficiency
- Advanced identification of potential problems, minimizing unscheduled downtime
- Proactively scheduling repairs and part substitutions based on scheduled shutdowns and other operational considerations
AMRs are being used to make warehouse operations, manufacturing processes, and workflows more efficient and productive by picking up and dropping off materials, freeing up people to perform complex tasks that add value. As the variety of tasks using AMRs has expanded, new AMR formats have been developed, complicating the management of AMR fleets. Managing fleets of AMRs begins with simulating the interactions of AMRs in a synthetic environment before launching the fleet. Once the fleet has been deployed, AMRs must operate safely, efficiently, and with minimal downtime. Centralized hardware and software appliances are available that can be used to simulate potential AMR deployments as well as monitor the safe, efficient, and reliable operation of AMR fleets.