Unmanned Systems Technology 033 l SubSeaSail Gen6 USSV l Servo actuators focus l UAVs insight l Farnborough 2020 update l Transforma XDBOT l Strange Development REVolution l Radio telemetry focus

26 Dossier | SubSeaSail Gen6 USSV top and bottom, so it floods naturally as the boat submerges. To keep the wingsail at the optimum angle with respect to the wind for efficient propulsion, SubSeaSail has developed and patented a passive automatic wing control mechanism. Eschewing the use of complicated and expensive electronics, pulleys and lines, the mechanism works by a combination of aerodynamic forces and a cam with a spring-loaded follower system. The only electromechanical control device the vessel needs is a servo actuator for the rudder. A modified RC servo is used, and it is pressure- balanced, filled with oil and fitted with a spring mechanism to prevent any overloading – perhaps from accidental pressure on the rudder – while it is being handled during launch, recovery or maintenance. It accounts for most of the electrical load the boat imposes, amounting to less than 1 W ‘house load’ (every load other than propulsion). The upper region of the buoyancy section houses an inertial measurement unit (IMU) and navigation electronics, including the GNSS receiver and the autopilot. A ballast tank and related pump system to control submerging and surfacing (in versions with this option) are installed in the lower region of the float module, which can also accommodate payloads. The main hull under the water provides space for internal and external payloads, and contains ballast – which can be lead or bismuth alloy – and a nickel metal hydride (NiMH) battery pack. It can also be modified to accept payloads to suit various missions through the use of modular, interchangeable nose caps. At the aft end of the hull there is a T200 electric auxiliary thruster from Blue Robotics that is used for maintaining position inside predetermined survey areas and when sailing close to the shore in light winds. Fitted with a proprietary propeller, the thruster typically generates between 5 and 10 N of thrust and draws 5-20 W of power. Also attached in this area is a passive stabiliser that is designed to minimise pitch in higher sea states. Power generation and management Electrical power is generated by custom polycrystalline solar panels with an average output of around 5 W and a peak of almost 25 W. They can be mounted on the deck of the float module, inside the transparent wing structure, or they can form the outer wing skin. The power management system is based on a maximum power point tracking (MPPT) controller, and is configured to allow the solar panels August/September 2020 | Unmanned Systems Technology The Gen6 main hull has an interchangeable payload module in the nose. Above it are the keel, rudder post and rudder This exploded view shows the major components. Note the computer module in the centre and the sail regulation mechanism at the upper left