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the problems: increasing the power of the propulsion system and developing articulating thruster mounts. This year, Team Kanaloa decided to double the thruster force to 110lbs, mitigating the problem of not being able to hold position in certain orientation. However, to mitigate the efficiency disadvantage of the holonomic drive configuration, articulating thruster mounts were developed, providing the WAM-V the capability to mechanically change the propulsion system from a holonomic configuration to a normal drivetrain. The capability to switch from holonomic to normal provides the WAM-V with benefits of both drive configurations. Assuming the boat is moving at 3 knots and force is applied on the motor shrouds, computational fluid dynamics (CFD) was used and resulted in a max moment of 65 Newton-meters. Therefore, articulating thruster mounts were designed to utilize a worm gear, stepper motor with a torque of 12 Newton-meter, and a 1 to 5 gear reduction to combat the CFD max moment as shown in Figure 3.

battery shipments are expensive and difficult. Therefore, the team modified the current battery system by putting them in series, ultimately becoming a 50V power system.

### B. Hardware System

#### 1) High Current Box

The high current box of the Team Kanaloa WAMV contains all components capable of effectively controlling a minimum of 50A. These components play the pivotal role of controlling the propulsion system. Effectively controlling the increased voltage requirement of the 110lbs thrusters required replacing the previous higFh igcuurrere :n 5t 0bVox P. o Twheer mSyasjoterm iteration of the c hange in the high current box was replacing the previous motor controllers, four REV Robotics Spark motor controllers, with motor controllers capable of inputting 50V from the power system. During testing of the motor controllers, it was discovered the motor controller’s internal voltage polarity inverter was inoperable after switching the polarity of a large amount of voltage. In other words, if the WAMV was required to go from full forward to full reverse in a short period of time, the WAMV would be unable to return to full forward. To circumvent this issue, external reverse contactors replaced the motor controller’s internal voltage polarity inverters. A 5V regulator was needed for a relay board on the reverse contactors; the relay board acts as a kill switch to the thrusters. The previous motor controllers in the old high current system were controllable using pulse width modulation (PWM) signals. The new motor controllers operate on an analog signal. One possible option for sending analog signals was using a digital analog converter. This possibility was explored but had too many issues which couldn’t be resolved in a timely manner (see Ineffective Solutions section). The solution that was ultimately chosen was using the Arduino’s PWM pins with a low pass filter to replicate an analog signal. Low pass filters were designed for PWM frequencies of approximately 500Hz. Another issue the new motor controller posed was increasing levels of interference in the high current box. This increase in interference caused digital signals to components, such as the relays, to float; resulting in uncontrollable rapid switching of power to the thrusters. To help remedy this issue, major rewiring was required. Previously, the master Arduino (controls majority of functions in hardware box except power kill switches) read the voltage of the power supply directly using a voltage divider; with this information the master Arduino can better determine how much power the motor controllers can draw from the power supply preventing overdraw. With the new arrangements, an Arduino Mega was added to the high current system which primarily reads the battery voltage, then sends an analog signal to the master Arduino scaled based on the voltage of the batteries. To ensure interference does not affect signals from the low current box system, which contains all components

###### Figure 3: Top view of articulating thruster mount

#### 2) Modular Mounting Rack

Team Kanaloa designed, prototyped, and developed a Modular Mounting Rack (MMR) as shown in Figure 4 for instrumentation on the WAM-V which includes the battery, hardware, and sensor system. The mounting rack was made to be mission adaptable for various instrumental setups.

###### Figure 4: MMR

#### 3) Power System

The team must upgrade the power system to accommodate for the new propulsion system of four 110lbs thrusters. In the old configuration, the team only required 12V for the 55lb thrusters, but 36V is required for the 110lbs thrusters. Due to Hawaii’s geographical location,