USE Network launch I UAV Works VALAQ l Cable harnesses l USVs insight l Xponential 2020 update l MARIN AUV l Suter Industries TOA 288 l Vitirover l AI systems l Vtrus ABI

78 In operation | Vitirover UGV 15 cm – for the UGVs to then cut it to between 4 and 10 cm, a height that can be adjusted remotely. Once a price for the job is agreed, Vitirover delivers the requisite number of UGVs, each to a predetermined GNSS coordinate within range of their allocated swathe of mowing. The average herd will typically consist of around 50 UGVs. Each individual vehicle will be expected to mow a permanently assigned (until the contract for the herd expires) area of no more than 5 acres, meaning that a herd will most often be allocated about 250 acres (1 sq km). The solar panel on the rooftop allows each Vitirover to recharge its batteries during operation. If the power falls below 10% of capacity however, it will stop working and go to an assigned location to recharge while stationary, before returning to mowing. In sunny weather, this will take about six hours. If the sky is cloudy, the robot can wait as long as is necessary (even if that takes several days) to charge, before picking up where it left off. Alternately the fleet manager (or ‘shepherd’) can come and change the battery manually if the mowing job needs to be completed urgently. Shortly after delivery, before starting work, each UGV connects to Vitirover’s cloud server by 4G to download key mission information such as mowing routes, waypoints, potential obstacles and other factors. Through the fields The Vitirover moves around using four electric wheel-hub motors to maximise its gripping area when working over potentially soft soil. It has a standard operating speed of 0.3 kph and a maximum slope tolerance of 20 º . Each vehicle has three rotating cutters (or ‘grinders’) that give a cumulative cutting radius of 32 cm. “Each grinder is powered by its own electric motor, with an additional motor/actuator installed for raising and lowering the grinder rail,” de la Fouchardiere says. “Those plus the ones for the wheels make for a total of eight electric motors on each vehicle, all supplied by Maxon Motor.” A robust navigation system is needed to ensure grass is cut in precise patterns and areas, as well as to guarantee that the UGVs do not wander off-path into obstacles, ditches or train tracks, or damage end-users’ assets such as crops or electrical cables. Vitirover’s engineers have therefore installed two GNSS systems on each vehicle. Primary position fixes are given by a Trimble RTK-GNSS receiver coupled with an IMU, enabling centimetre- accurate navigation along mowing paths. Additional GNSS data comes from a second, optional multi-channel Trimble RTK-GNSS, which enables a wider array of satellites – specifically the GLONASS, BeiDou and Galileo constellations, in addition to GPS – to maintain an incoming stream of positioning signals. This is especially important for robots working in industrial areas, where precise positioning is key for reasons such as safety and security, for example when operating along high-speed railways. The Vitirover needs about 20 satellites to maintain its positioning accuracy. When fewer than 20 are available, the precision of the RTK-GNSS will drop. If at any point along a high-speed railway the GNSS signal’s margin of error is calculated as being greater than 10 cm, the Vitirover is programmed to stop where it is until it has acquired position fixes from enough satellites again, to avoid the potential collision hazard from trains. However, context-sensitive exceptions to this rule can be written into the Vitirover’s movement software to improve operational efficiency. For example, if part of a customer’s land includes a large lawn with no critical assets or obstacles in the middle, the UGVs can be programmed to continue operating with a 1 m error rate when away from the lawn’s edges. June/July 2020 | Unmanned Systems Technology Each of the four wheels is powered by a Maxon Motor DCX 22 L series brushed DC electric motor, for an operating speed of 0.3 kph