Open Ocean Robotics ASV Winch:  University of Victoria Student Capstone Project

Ryan Foxall, University of Victoria

Open Ocean Robotics is a Victoria based start-up that designs, builds, and operates autonomous surface vessels (ASV) for scientific data collection. A team of six engineering students from the University of Victoria (Figure 1) were tasked to design an automated winch to be mounted to an ASV for sensor deployment as seen in Figure 2.

The winch was required to deploy an AML Base•X₂ SVP sensor package from the vessel down to depths of up to 300m, avoid line tangling, and securely stow the sensor payload away, with ability to add inductive charging in the future. The plan was to develop a working prototype and provide testing results. However, because of machine shop closures due to COVID-19, the design was pivoted to a theoretical based design, with more emphasis on analysis and concept iteration. Stress analysis simulations were completed on a number of components to ensure structural integrity. This enabled weight reductions in parts and geometrical optimization.

The winch uses a 12 V brushless DC motor to drive a spooling system (details in Figure 3). The line is neatly arranged onto the spool using a self-reversing diamond lead screw.  To avoid line tangling, a tensioning device was implemented at the end of the static arm. This consisted of two counter rotating pulleys, mounted vertically on top of one another, with a downward force between them provided by springs. Line counting is done using a magnet and Hall effect sensor mounted to the tensioner. A 3D printed cup was mounted at the end of the static arm to guide sensor docking, to provide a secure location for the sensor when not in use, and to position the sensor against an inductive charging plate. Highly corrosion resistant materials, such as stainless steel and various plastics, were chosen due to the saltwater environment. Rapid prototyping methods, such as laser cutting and 3D printing, are central to the design methodology to reduce costs and production time.

Open Ocean Robotics is keen to bring this concept to life and provide their clients with reliable sensor deployment in the near future.

The team would like to thank IEEE OES Victoria Chapter for their contribution, Open Ocean Robotics for their mentorship, and their instructors at the university for their guidance and feedback.