Team members (back row, from left) Wyeth McKinley, Oli MacGregor, Freddy Angarita-Cuesta, Jessica Kies, (front row) Alan Lopez, Anna Frey and Scarlett Spindler pose next to their self-navigating, cargo-carrying sailboat. (Image: Jeff Fitlow/Rice University)

A self-navigating, cargo-carrying sailboat designed by a team of Rice University engineering students could be a sustaining link for Marines hunkered down on shore during war. The goal is to carry 60 pounds of cargo or more.

“Most of the existing autonomous sailboat designs out there are targeted toward ocean research or racing,” said team-member Anna Frey. “That means they’re super lightweight, not meant for carrying cargo.”

“This is the first autonomous catamaran sail design that we know of that’s intended to bear load,” added Oli MacGregor.

The project’s engineering demands entail mechanical, electrical, and programming components. Frey, a mechanical engineering major, was in charge of designing the rudder, sail, and body of the vessel. “Because it’s an airfoil shape, the sail creates lift when you angle it in the wind — it’s basically a sideways airplane wing, which propels the boat,” she said. “The wind vane in the back helps guide the sail into position.”

The vessel is equipped with a number of sensors integrated into a self-correcting navigation system.

“There’s a couple of main subsystems in the boat,” MacGregor said. “You’ve got a sensor that measures the direction of the wind. The GPS sensor gives the current coordinates of the boat. You’ve got a magnetometer, which is a digital compass that can tell you your bearings and where you’re facing. That helps determine which direction the boat should be going and how it should position its wind vane.”

In favorable wind conditions, the boat adjusts its course to a trajectory devised using the coordinates of its current location and those of its target destination. However, things get more complicated if the boat is sailing against the wind in a so-called “ no-go zone” where it cannot generate lift due to the opposing wind direction. “That’s actually been the most challenging aspect of this project,” MacGregor said.

“Whenever the destination is in the no-go zone, the boat cannot approach it via a direct route,” Freddy Angarita-Cuesta said. “So, the main idea to get around this is to create a series of artificial or temporal waypoint targets alternating along either side of the no-go zone perimeter in a zigzag pattern.”

The students are also working on equipping the boat with a communication link to a satellite network that would allow it to stream back data from any location around the globe for further engineering development.

“The communications module that connects the vessel to the satellite constellation gives us the ability to send data back to the ground station,” Alan Lopez said. “We’re going to collect all of the sensor data, including the magnetometer information, the bearing, the wind speed, the current GPS location, etc., so that we can use it to debug and improve our tests as well as to check our progress.”

The students’ choice of materials and component parts sought to optimize the cost-to-efficiency ratio. Moreover, autonomy was a guiding design principle not only in terms of navigation, but also with respect to energy consumption.

“It’s all solar-powered,” MacGregor said. “It produces enough electricity through its solar panels to power the systems several times over. It also collects excess energy in batteries that live on the boat. So, in cloudy weather or at nighttime, it can still power itself.”