Issue 39 Unmanned Systems Technology August/September 2021 Maritime Robotics Mariner l Simulation tools focus l MRS MR-10 and MR-20 l UAVs insight l HFE International GenPod l Exotec Skypod l Autopilots focus l Aquaai Mazu

77 Exotec Skypod U3DV | In operation fetch an item from a rack and take it to a pick station to be processed for delivery. ASTAR connects to the end-user’s existing warehouse management system (WMS) via an API. ASTAR also autonomously tracks and plans orders, prioritising them according to importance where necessary. Included in this are tasks such as querying the WMS on the contents and lines of each new order, transmitting waypoints over wi-fi for the robots to follow to obtain the necessary items, optimising their routes in real time, and recording all positions and movements of the robots and stock. “Route and traffic management are key,” Lueg says. “Collisions and traffic jams would be really problematic for the efficiency of an end-user’s operations, and even outside these types of events we still want to make sure the robots always make the most efficient use of their space. “Once a robot has received the navigation information for a new order, it heads over to collect the first items, waiting in a dedicated space we call the ‘accumulation zone’ if there’s a bit of traffic near its destination aisle. And to prevent crushing of picked items or similar problems, it is told to collect them in order of heaviest first, so the lightest items go on top.” Localisation and tracking of the Skypods occurs via unique physical markers (such as 30-40 cm pins), located at known places and orientations next to the racks and aisles for each robot to identify with its Lidar scanners. Based on this location information, a Skypod can identify when it is at the correct aisle, and count down to the correct rack (and then up to the correct compartment as it moves vertically) by the number of passes detected by its Lidar. Also, its IMU drift can be reset as it localises itself by pin or rack, and its approximate real-time location and heading updated in the ASTAR feed. Once the robot is at the correct ground location for an item, its climbing system (being separate from the floor traction system) engages with the racks, enabling it to move upwards at a top speed of 2 m/s. When it recognises that it is at the correct storage compartment, a system using a telescopic servo actuator either pushes a bin from the Skypod into the compartment, or hooks a bin from the compartment and pulls it onto its platform. “When the Skypod comes back down, we don’t drive the motors in the opposite direction, we let the robots descend under their own weight via gravity, and they use that motion to drive the motors as generators,” Lueg explains. “So when they’re descending, they’re regenerating energy for the batteries and reducing the downtime they need later at the charging stations.” Upon landing, the Skypod ferries its cargo to a pick station, where it drives up to a U-shaped ramp at approximately waist height for a worker to take the goods and process them for delivery. The robots’ empty bins can be retrieved by a worker here, and re-stocked to conduct a new delivery to a particular shelf. In that case, the Skypod navigates back over to the racks to transport its cargo up to the appropriate space. A problem can arise when taking goods up the racks for storing though. As the distribution of weight inside the bin is rarely uniform, the Skypod’s centre of gravity can change, forcing some parts of the climbing system to work harder Unmanned Systems Technology | August/September 2021 The Skypods’ wheels are located at the middle of each side rather than the corners, to enable turning on the spot and prevent tilting when cornering at speed The Skypod is the only moving part in the infrastructure, and the only part with wiring, which is very important from the perspective of fire suppression