48 Digest | Addverb Dynamo 1T Load distribution Inside the robot is a chassis with a cabinet-like design. Within that are the control computers, suspension components for load distribution and to make sure the drive wheels always maintain ground contact, as well as a frame that has been formed for broader distribution of a 1000 kg load. To that end, large and sensitive interior components such as the battery are also placed and housed in a way that guarantees loads are distributed evenly across the pack. “With this approach we also make sure the centre of gravity remains at a constant height and position for keeping material transfer operations as safe and smooth as possible,” Jain adds. “The cabinet-type chassis also makes maintenance quite easy, as components can be swapped in and out for inspection and servicing without difficulty.” The frame is steel, and features numerous heat sinks about its interior for thermal management of the densely packed electronics. Meanwhile, the body covers are fibre-reinforced plastic formed using injection moulding techniques; Addverb declines to disclose further details about the mechanics. “Load-bearing in a warehouse environment isn’t just about mechanics,” Pattnayak notes. “Any AMRmust alsomove with fine-tuned dynamics, evenwhen stopping or navigating to avoid obstacles. “The differential drive and motor control for instance had to be extensively tuned and corrected for very balanced movement and very smooth torque and acceleration, to avoid any danger to a pallet or to the robot from the inertia of a pallet being carried. That meant control systems from the motor to the main computer had to be continually adjusted for such smoothness in normal, uninterrupted operations, and also for when they were reacting to something picked up by the perception systems.” Navigation and autonomy Localisation is executed using different arrangements of components in different warehouses, as each user will have their own preferred trackers and beacons, as well as Lidar-based tracking, SLAMor other ways of localising assets insidewarehouses whereGNSS cannot be relied on. “On the use of SLAM for localisation, my engineers and I spent several weeks training the Dynamo robots in all types of warehouse simulations, within which were all types of floor traffic, lighting, everything you can imagine, and then we deployed it for testing in a real warehouse,” Pattnayak says. “All those hours of simulation did not translate to any success in that first realworld test though. We can’t emphasise enough how challenging warehouses are for getting an autonomous system up to scratch; the gulf between training an AMR and an autonomous road vehicle is enormous. “Warehouses are so dynamic and unpredictable, and the visibility you get fromonboard sensors is so limited, that you can use the best visual 3D SLAM algorithms in the world but put them4- 5 cm from the ground in a busy warehouse and you lose somuch of their capabilities.” Perception for the 1T is primarily powered by two Lidars, at opposite ends of the body to cover the full 360o around the robot. Addverb also has an alternative, less costly design concept for the 1T that uses a single Lidar placed at the centre of the body, with openings around it for a clear view ahead and to the sides of the UGV. However, the team and customers generally prefer to have complete coverage via the two-sensor configuration, given the safety and confidence of detecting and avoiding surrounding objects this gives. “The resolution of the Lidar data points was themost important thing for uswhen choosing a Lidar, but also keywas the FoV we could get with each sensor, because seeing asmuch as possible around the vehicle at all times ensures that we’re not compromising on safety,” Jain says. Pattnayak and Jain add that measurement distance was also critical for path planning, noting that the warehouse floors in which they work can be highly dynamic and even chaotic environments, and that navigating around one object is insufficient if an AMR cannot make additional plans for navigating around several other objects afterwards. “Furthermore, as well as potentially havingmany people and vehicles moving around, warehouses aren’t always consistent in howwell-lit they are,” Jain notes. “Somemight have very dark spots, others will have really bright spots, so testing and trialling Lidars for howwell they continued delivering accurate data points across a wide range of light intensities was really important. And the robot is safety-certified, so the Lidars and other components had to be similarly certified.” The 3Dcamera systemon the 1T provides a second layer of data points, and the June/July 2023 | Uncrewed Systems Technology The 1T and the smaller UGVs in the series have been designed after consultation and research into warehouse environments
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