Unmanned Systems Technology 027 l Hummingbird XRP l Gimbals l UAVs insight l AUVSI report part 2 l O’Neill Power Systems NorEaster l Kratos Defense ATMA l Performance Monitoring l Kongsberg Maritime Sounder

76 In operation | Kratos Defense ATMA navigation information, to ensure speed and heading are constantly being received by the follower truck over the ATMA’s data link. From the user interface, the operator can also drag a bar to select the commanded gap – the distance the follower vehicle should maintain between itself and the leader. The radio transmission components are installed behind the driver’s cockpit, and the main computer beneath the seat (referred to as the system control unit, or SCU) is an FPGA processor board designed in-house by Kratos. An SD card is typically installed in the SCU to log navigation and performance data. “The system is designed in such a way that it doesn’t interfere with the normal operation or ergonomics of the vehicle – we don’t want anything in the way, and we may adapt it differently for different vehicles,” Factor notes. “This system works for Royal Truck & Equipment, but we may design our retrofit kit and integrate our computers, sensors and notebook PCs slightly differently, or very differently, based on a different company’s trucks and attenuators.” In line with this objective, the retrofit kit is powered by the truck’s onboard battery. Overall, the kit requires less energy than the hazard lights and the various other items typically installed on highway construction vehicles, as Factor and his team wanted to avoid installing an extra battery on either vehicle. Outside the cockpit, both the leader and follower vehicles have a primary GPS antenna installed, normally mounted atop the frame on the front of the trucks to ensure the clearest possible line of sight between the antennas and positioning satellites. A secondary GPS antenna is typically installed for redundancy, and another antenna is installed to transmit emergency stops (switches for which are installed around the two vehicles and in the lead truck cockpit). Both GNSS antennas are AG25s from Trimble. “Often these trucks will be used in a stationary or slow-moving construction zone – maybe with the two vehicles moving at between 8 and 24 kph – and sometimes there are people walking around or between them,” Factor says. “So in the event that some safety- critical concern arises, we have installed emergency stop or e-stop switches around the follower vehicle for any worker to jog over and hit one, which will shut it down immediately.” Additionally, in the lead vehicle cockpit, the driver and operator have access to an independent back-up e-stop. That will stop the follower vehicle, shut down the engine and all the other systems, and fully engage the brakes; it is on its own dedicated wireless interface. That separate data link is encrypted and untied from the vehicle computer and the SCU in case the other e-stops are affected by a failure in another onboard system. Pre-mission checklist Before any highway work is carried out, additional safety is provided by a set of pre-mission checks. These are typically carried out at wherever the day’s work is to start, having manually driven both trucks from their depot or from a staging area in the vicinity of the highway. “The prototype system was sort of a baseline when we first deployed it – we were trying to figure out which parts we needed and if there was anything important the system lacked,” says Factor. “For example, we had the leader- follower system, but we didn’t have a user interface.” That interface was developed in response to initial feedback from Colas and the Colorado Department of Transportation, which was trialling the system towards making it certifiable for US operations. Similarly, a standard checklist for drivers and operators to run through was developed in response to user requests. As Factor notes, “A checklist and training with an easy-to-follow structure enables users to smoothly incorporate the ATMA into their work routines.” First, the driver starts the leader vehicle’s engine, releases its parking brake, then switches its battery breaker to ‘on’. That connects the ATMA SCU to the vehicle’s battery, and must be done in order to have power supplied to the operator’s control panel, data August/September 2019 | Unmanned Systems Technology A number of emergency stop switches are located around the follower truck, which are designed to shut off engine power and activate the brakes