FishPi: How Raspberry Pi controls an autonomous ocean explorer

FishPi is a project for developing the prototype of a sun-powered autonomous ocean-going surface transport controlled by a Raspberry Pi (RBPi). The project is working on a small boat, to be propelled by solar energy to traverse the Atlantic Ocean and during its journey, the boat will be taking pictures and gathering data.

The goal of the FishPi project is simple. They intend to develop FishPis ranging from vessels running on batteries for a few hours to solar powered vessels full of features and capable of sustaining months at sea. The vessels will be MUSV or Marine Unmanned Surface Vessels, which will be capable of crossing the Atlantic ultimately and unaided.

An RBPi unit will provide all the command and control features of the FishPi vessels. The vessel will have an onboard solar panel, and the RBPi will control the data logging, navigation, power management and control of other devices on-board. The solar panel will charge a Lithium-ion battery pack, which will be driving a ducted propeller system. The Amateur Radio Satellite Network will be used to transmit images from the FishPi to the shore, by using satellites to integrate the ship-to-shore communication system.

During its journey, FishPi will use its environmental monitoring and data-gathering capabilities to measure the temperature of the air and sea, salinity and pH, barometric pressure, light levels and more. It will transmit some of the data along with images relayed in real-time.

For this, the RBPi is attached to a 16-channel PWM, a temperature sensor, a compass, a GPS, a USB webcam, a USB Wi-Fi dongle and a RockBLOCK satellite communicator. All these, except the compass and the webcam, are within a box on the FishPi Proof-of-Concept Vehicle or POCV now.

Initially, the base-station was planned to be connected to the POCV with a 32-core cable. However, this became too complicated and caused a lot of interference, so it had to be abandoned. Presently, the base-station contains another RBPi, connected to a USB hub and a 4-port Wi-Fi Router. The Wi-Fi link allows real-time remote control possibilities with the use of xrdp and the FreeRDP client. Additionally, this allows live video streaming to the world over the internet.

The electronic speed controller, the webcam, rudder, temperature sensor, the GPS and the compass are integrated with the C&CS or Command & Control System of the POCV. Currently, the coding is for manual control only, and the POCV can move forward, backward, to the left and to the right. With the webcam as a visual guide, the POCV can be driven remotely, but so far, this has been tested only indoors.

In the future, this control will be automated to the extent of giving the POCV the command and leaving it to navigate itself. For tracking, routing and waypoints, GPX files are being used while GeoTiff file formats are being used for the maps. Telemetry is an important function for any ocean-going vehicle. The POCV will be communicating both ways via the RockBLOCK Satellite Communication link.

There is always a chance that the vehicle can capsize in rough seas, and therefore, next in line is a self-righting mechanism.