Drives & Controls July / August 2022

36 n ROBOTICS AND AUTOMATED MANUFACTURING July/August 2022 www.drivesncontrols.com Will AMRs revamp factory designs? A utonomous mobile robots (AMRs) are being used in many industries in a variety of logistics applications. Unlike material transport systems such as conveyors, AMRs are not limited to fixed routes. Their wireless communications and onboard navigation systems allow them to receive commands telling them where to go next. AMRs can navigate to a requested location without being programmed and can even find an alternate path if they encounter an obstacle. They can make warehouse operations, manufacturing processes, and workflows more efficient and productive by performing tasks such as picking up, transporting and dropping off materials, thus freeing up people to perform more complex tasks that add value. Although AGVs (automated guided vehicles) can deliver materials to specific locations with more flexibility than a conveyor, they are much less flexible than AMRs. Like conveyors, AGVs have fixed routes. But with AGVs, the route can be more easily and quickly modified than with conveyors. AMRs can work collaboratively with people, offering much more flexibility, and finding the most efficient route to accomplish a task. If an AMR encounters an obstacle, it can change its course and continue to its destination. If an AGV encounters an obstacle, it usually has to stop and wait for assistance before it can continue along its preassigned track. AMRs use a combination of onboard and centralised computing power and sophisticated sensors to interpret their environment and to navigate around both fixed obstacles – such as racks and workstations – and movable obstacles – such as forklifts, people, AGVs and other AMRs. AMRs can be integrated with warehouse control systems and distribution centre environments, giving them the flexibility to create their own routes between locations. The result is that they are better able to work with humans in the dynamic environments of order fulfilment and warehousing operations. Some AMR applications, such as material deliveries to conveyors, feeders and testing stands, require the robot to stop at a specific location accurately and repeatably. With Omron AMRs, for example, fleet managers can choose between two high-accuracy positioning systems; cell alignment position system (Caps) and high accuracy positioning system (Haps). These can improve the precision with which the AMR arrives at its goal from about ±100mm to ±8mm. Haps uses a safety scanning laser on the front of the robot to detect a target location. Safe operation is essential for AMRs. Safety sensors used on board include rear sonar and front lasers for obstacle detection, front bumper sensors to stop the AMR if it contacts an object, and light disks to alert people in the vicinity that the AMR is operating. Optional sensors can be added for specific requirements, such as identifying protruding or hanging obstructions. AMRs need 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) . It’s almost unheard of to deploy a single AMR by itself. Fleets of 100 or more AMRs are possible, and software is needed to manage their operation. Before the AMRs are even deployed, simulation software allows users to plan traffic and workflows for fleets and helps to identify and solve potential problems. AMR localisation, path planning, obstacle avoidance, task simulation, and fleet management based on a map of a facility can be modelled accurately. In addition, simulations can be used to optimise the composition of an AMR fleet and to predict throughput. 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 starts by 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. Centralised hardware and software appliances are available that can be used to simulate potential AMR deployments as well as monitoring the safe, efficient, and reliable operation of AMR fleets. n Autonomous mobile robots (AMRs) could disrupt the way factories and warehouses are designed and operated, replacing traditional inflexible conveyor systems and fixed- route AGVs (automated guided vehicles). Rolf Horn, an applications engineer at Digi-Key Electronics, looks at how AMRs work and how they compare with existing technologies. Autonomous mobile robots have the flexibility to reroute themselves around objects they encounter as they move around a plant Software can be used to plan AMR installations and to manage fleets of vehicles once they are operating