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80 In operation | Kalmar AutoStrad management of horizontal transportation at Kalmar, notes that cybersecurity of critical national infrastructure – particularly harbours and cargo terminals – is an issue that must not be neglected when introducing autonomy and AI into large-scale heavy industries. “There are certain ISO standards that we are working towards in a number of ways,” he says. “How we build our facilities, the way we build the software and the speed at which we can detect threats mean roll-out security patches will become really important. “Of course, initial installations of our automation systems always come with firewalls around them, as well as segregated comms as an added safeguard. Technically it isn’t the responsibility of equipment suppliers such as ourselves to provide cybersecurity, but doing so helps provide a higher quality and longer lasting product.” Navigation infrastructure Before autonomous operations can begin, the end-user must choose their navigation system. In harbour terminals, relying on GNSS for position and heading information without an aiding system is highly inadvisable, as the metallic structures and ships at terminals create too much interference with satellite signals for them to be consistently accurate or safe. As a result, Kalmar offers two approaches, which are selected according to customer preferences on cost, maintenance practices, safety levels and other factors. The more rudimentary of these is transponder navigation, in which a network of programmable RFID-based transponders is installed throughout the terminal’s lanes; sensors on the undersides of the carriers use them for localisation and orientation information. This approach requires a high initial investment in costs, time and labour. Thousands of transponders (as well as comparatively less expensive sensors in the straddle carriers) have to be installed throughout the cargo yards, but this minimises the associated operating and maintenance costs. “Our newer, second navigation approach is supplied by Locata, an Australian company that develops local GPS hotspots using ground-based constellations of radio transmitters installed around the terminal,” Alho says. “That allows the carriers to measure their distance and heading against them to localise themselves.” Like GNSS, Locata’s system uses a direct sequence spread-spectrum signal structure to transmit signals over the 2.4 GHz band that can be used by mobile receivers on the straddle carriers to output position, navigation and timing information. However, the close proximity and ground location of the transmitters – as well as Locata’s designs – enable range and phase measurement rates of up to 25 Hz (compared with up to 20 Hz on GNSS) as well as continued operations amid multi-path or similar issues that would cause GNSS outages. “Locata’s system tends to be chosen for terminals with a lot of wide, open space, but if a terminal has narrower or fewer corridors, meaning restricted space for movement relative to the number of straddle carriers, end-users tend to choose transponders,” Alho says. “That’s principally because they need less investment in their ground infrastructure – the most expensive and laborious part of navigation equipment integration – relative to their number of carriers. “Also, if requested, we can install both systems on a carrier, so that if one system temporarily drops out the other is still available. We install an IMU on each carrier as well, which gives aiding information on acceleration and angular rate in all degrees of freedom, as well as wheel encoders to measure all four wheels’ rotational speeds and steering angles. All the sensor information is fused and processed on board the AutoStrad and included in the navigation processes.” Fleet planning and autonomous operations During operations the terminal overseers have access to all the data on navigation, power consumption and health of the carriers. However, since each overseer might be monitoring up to 40-50 AutoStrads at a time, this data is typically not immediately visible in the user interface and is not consulted unless there are issues that make it necessary. If a fault or accident should occur, the supervising technician will receive an alert through the central automation December/January 2021 | Unmanned Systems Technology Traction is supplied by four electric motors, with driveshafts running down the vertical beams to wheel-hub gearboxes