110 In operation | Armach Robotics HSR Assessing the job Before starting to clean any ship, the first task is to verify the condition of the hull coating and the level of fouling. As the robot can only clean micro-fouling, it is essential to be sure that the ship is in a suitable condition. Armach then works with the ship’s owner and agent to coordinate access to it. “TheHSR operates using supervised autonomy, so the pilotmonitors its progress, while another member manages the tether,” Lander says. “In some locations, we can use a tether management system that reducesmanpower needs. That capabilitywill continue to evolve, making the evolutionmore efficient. “On the day of cleaning, the team arrives at the pier with a mobile operations centre and two to four team members,” he says. “Once the approval is granted by the ship’s owner, the robots are manually launched and ‘flown’ into position. With the number of thrusters we have on the HSR, it’s easy to roll – the operator rolls it 90o, attaches it to the hull and switches it to crawler mode. “The pilot will then do a quick survey to get an idea of the area we are trying to cover, and program that into the vehicle, essentially telling it to ‘drive around this area in this pattern’. The software will allow you to just select a pattern and then hit ‘Go’. At that point, the operator can put the controller down, sit back and watch to make sure the robot is doing its job and is not stuck in a corner.” Watching the imagery on the Sidus Solutions forward-looking video camera, the operator can see what the HSR is coming up to next and assess the conditions. Any areas with no fouling, have macro-fouling that the robot is not designed to deal with or show damage to the coating, can be avoided. “With the software it is easy to set exclusion zones, and the robot has its own obstacle avoidance capability as well,” Lander says. Almost SLAM Themain engineering challenges in the HSR’s development centred on the technology needed to navigate and operate autonomously in a GPS-denied environment that also has the ship’s hull rather than the Earth as its frame of reference, according to Lander. The HSR finds its way around the ship using a proprietary system the company calls hullrelative navigation, which uses sensors and software that provide capabilities close to those of simultaneous localisation and mapping (SLAM). “It’s a slightly different approach, so we’re not calling it true SLAM, but that’s essentially what it is,” Lander says. The system creates a new coordinate frame based on the ship itself, and the vehicle uses a multi-sensor navigation system that includes odometry, inertial devices, and a Doppler Velocity Logger (DVL) from Water Linked, to find its way around, assisted by forward-looking sonar and camera imagery. Including the DVL in the navigation system provides an independent set of motion cues derived from direct sensing of the environment immediately around the robot. “The DVL pings off the ship’s hull to give us another piece of information on how it is moving in relation to the hull,” Lander explains. If the robot gets stuck but the tracks are still spinning, for example, or the tracks are stationary but the robot is sliding with the current, the odometry will not detect that but the DVL will. “It helps correlate what the robot’s other sensors are seeing,” he says. The odometry system is integrated into the motors that drive the tracks, a solution engineered in-house. June/July 2023 | Uncrewed Systems Technology The HSR in action, using its rotary brushes to clean micro-fouling from the surface of the hull without damaging the paint, and using hull-relative navigation to find its way Any areas with no fouling, have macrofouling that the robot is not designed to deal with or show coating damage, can be avoided
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