During the competition, several safety measures have been implemented in order to ensure the safety of our team and other participants in the competition. The most important is the remote and onboard emergency kill switch. The onboard kill switch is large and easily reached by personnel. Our vehicle can be terminated by our ROS system and by our handheld RC controller. A visual display system is also in place to depict which mode of operation the boat is in. The modes of operation and their corresponding colors are blue for autonomous, yellow for manual, and red for active emergency stop. Additionally, all wires are properly covered in shrink tubing, so an electrical shock is not possible when entering the electronics box. All electronics are fastened securely and positioned to decrease the risk of overheating. Waterproofing is also ensured. Battery safety was a major concern of ours. Throughout the competition, all of our lithium-ion batteries will be properly stored in a fireproof LiPo bag at a suitable temperature. We have battery safety documentation on hand and protocols in place in case of an emergency.
The boat and its electrical components are powered by a 14.8V, 15.6Ah lithium-ion battery. This high-capacity battery will provide more than enough power for the boat to operate throughout the competition and hours of testing. The power system also includes a series of voltage and current regulators to deliver power to our 48V, 12V, and 5V, subsystems. Additionally, a kill switch circuit has been implemented to disconnect power from the thrusters in situations where the boat acts unexpectedly. All the relays and regulators featured are rated for their respective voltages and maximum currents that each electrical component draws upon.
Our sensor hardware mainly features Stereolabs’ ZED 2i camera. This camera provides us with all of the necessary environmental information while remaining durable, water-resistant, and equipped to handle challenging outdoor environments. Key features include its dual, wide-angle cameras with a polarizing filter and built-in 9-DoF IMU. Combined with the provided SDK, these features all result in depth perception from 0.2 meters to 20 meters, 3D position tracking and mapping, and object detection. This environmental awareness is necessary for the boat to make decisions during challenges. Sensors are also incorporated to monitor battery health to determine if the battery is safe to operate.
The main computer used on our boat is a Jetson Nano, where all the sensor and control information is received and processed. This computer has advanced AI performance (472 GFLOPS), detailed graphics rendering (128-core GPU), 4GB of RAM, and impressive computing power (quad-core ARM Cortex-A57), which means it is perfect for interfacing with the ZED 2i and supports all of our CV and AI needs. The Jetson communicates with an Arduino Mega microcontroller through UART serial in order to control low-level hardware, which includes the T200 thrusters, stepper motors for the aiming mechanism, and motors for the water pump and skeeball flywheel. The Arduino communicates back to the Jetson with RC information, battery activity, and the status of the boat in general (e.g. killswitch activated or any errors). The Jetson Nano has an installed wifi module so it can communicate with our base station through ROS.