Unmanned Systems Technology 028 | ecoSUB Robotics AUVs I ECUs focus I Space vehicles insight I AMZ Driverless gotthard I InterDrone 2019 report I ATI WAM 167-BB I Video systems focus I Aerdron HL4 Herculift

55 names its cars using lower case letters). The gotthard was originally designed and built in 2016 for electrically powered racing, and was revived and updated for the 2018 driverless season. Key aspects of the updates included a new high-voltage accumulator, sensors for its perception architecture, and actuators for braking and steering. The gotthard is a four-wheel-drive, electric open-cockpit vehicle, capable of accelerating from 0 to 100 kph in 1.9 s. “The ‘empty’ car weighs about 173 kg, but that’s gone up to 182 kg with the weight of the sensors and processors for autonomy,” says Hendrikx. The core objective that AMZ Driverless had to tackle was a 10-lap race, each lap being 500 m long – with multiple straights, turns, chicanes, and hairpins – to be completed in the shortest time possible. The course is entirely unknown to them before the race begins. The team was told that the left side of the track would be marked by blue cones measuring 228 x 335 mm, and the right side by yellow cones of a similar size. It therefore had to ensure its car would not only drive and accelerate quickly, but intelligently recognise and react to the track markers at high speed. The chassis is made predominantly from carbon fibre-reinforced plastics, which have a sandwich structure. “Throughout much of the vehicle, you start with carbon composite on top, then you have a honeycomb-like layer of aluminium, then carbon again underneath,” Valls explains. “The three together provide superb strength-to- weight, with the general hollowness of the honeycomb proving especially good for weight reduction. “For the aero wings we use plastic as the honeycomb material. Where the honeycomb has to be bigger, say up to 20 mm in diameter, we need more rigidity in the material than plastic can provide, so a metal foam filler – aluminium, for its strength-to-weight ratio – was used in the body,” he says. Buhler adds, “The fasteners are mostly steel, as per the rules, and we use air springs with aluminium casings.” The chassis was designed in-house, with the larger sections of the fuselage manufactured at Swiss-German composites company Connova. Smaller sections such as the wings were produced using autoclaves at ETH Zurich, and the base materials were supplied by an unnamed Italian company. To make the gotthard as aerodynamic as possible, the engineering team used STAR-CCM for CFD modelling. This enabled each component of the car to be simulated individually and optimised for downforce and aerodynamic efficiency. After that, the entire vehicle was simulated and analysed to ensure that the aerodynamic balance of the car – particularly the centre of pressure – was as desired. “We wanted the centre of pressure to be a bit behind the centre of gravity, to enhance overall stability, and we ran hundreds of simulations during the design process to line everything up correctly,” Valls recounts. “We’ve also been using ETH’s scientific compute cluster servers. They’d run simulations for us in their cluster, which has much higher computing power than you’d find in a typical engineering office,” adds Buhler. The ETH scientific computing clusters are located in Zurich and Lugano, with a total of about 50,000 processor cores made available to researchers and academics for scientific calculations. Much of the gotthard’s architecture has been determined by the rules of Formula Student. For example, all the sensors have to be mounted in protected AMZ Driverless gotthard | Digest The sandwich structure gives superb strength- to-weight, with the honeycomb being especially good for weight reduction Unmanned Systems Technology | October/November 2019 The vehicle’s chassis is made largely of a carbon-aluminium-carbon ‘sandwich’