For a 4th year design project at the University of Waterloo, our team decided to build the Paddle Buddy! It is a portable device that mounts to the back of a canoe, providing a gentle thrust to assist with paddling. Inspired by the e-bike industry, Paddle Buddy aims to make canoeing more accessible. It uses a suction cup coupling system for secure, damage-free attachment and quick removal from the canoe. The electronics are housed in a carbon fiber enclosure, with a custom 4:1 gearbox that drives the propeller mounted below. I led the design and development of the electrical subsystem, with key requirements outlined below.
See here for a video of how the Paddle Buddy works!
Electrical Requirements
- Power Output > 100W
- Validated using hand calculations, market research, and motor testing
- Propeller Steering +/- 30°
- Allows the user to offset strong currents or even canoe with 1 person
- Operation Time > 2.5 hours
- Weight < 2.2kg
- Remote Controlled by User
Dashboard for testing motor and battery performance
System Architecture
- 20Ah 4S Lithium Polymer battery powers the entire system
- ESP32 microcontroller receives user input via Bluetooth from the remote controller
- High torque servo motor used to change the steering angle of the propeller
- Servo is controlled by the ESP32 and uses a buck converter to step down the voltage
- ESC (Electronic Speed Controller) used to control speed of BLDC motor which drives the propeller
- ESC receives a PPM signal from the ESP32 and uses duty cycle control to regulate speed
- ESC also sends speed and battery status feedback to the ESP32
- A fuse and anti-spark power switch are integrated for system safety
- RGB LED indicates the Bluetooth connection state of the Paddle Buddy
Hardware Mounting
- All electrical hardware is mounted within a carbon fiber enclosure
- Components are either bolted or adhered to a flat plate
- Plate matches the shape of the housing and is press-fit inside of the housing
- Servo motor is mounted just below the plate for steering the propeller
- Layout and geometry is optimized for minimal footprint
- Electrical manufacturing and assembly included soldering all hardware with cable sleeves and connectors for clean and organized wire management
Hardware Mounting Layout inside Housing
Final Assembly of Hardware Mounting
Final Build of Electrical System
Controller Design
The remote controller is a separate device that is kept with the user inside the canoe.
- ESP32 powered by 3x AA batteries (4.5V)
- ESP32 receives user input via QTY 4 tactile push buttons to change the speed or steering direction
- Notification is sent to the matching ESP32 on the Paddle Buddy to indicate a speed or steering change
- ESP32 also checks every 15s for an updated battery feedback from the Paddle Buddy
- LED indicators display the Bluetooth connection state and battery status for user feedback
Remote Controller Mounted to Canoe Yoke
Controller Housing
- Two perf boards contained inside the housing
- Lid Perf Board contains all of the peripheral devices (buttons and LEDs)
- Perf Board found in the base houses the ESP32 and any circuitry
- The two perf boards easily connect using jumper wires
- AA batteries mounted in the base for easy replacement
- Custom moulded silicone gasket
- Users press on the bosses found on the gasket, which deforms and clicks the tactile buttons mounted to the lid
- QTY 6 bolts secure the lid to the base and squeeze the gasket creating a water resistant design
- Strap hooks on either side for attaching the controller to the yoke inside the canoe
Takeaways
By designing and building the electrical system for the Paddle Buddy I developed a lot of skills that complements my mechanical experience. I learned how to spec a motor and battery based on the functional requirements of the product. I learned how to use KiCAD to design the electrical schematic. I developed firmware on an ESP32 for wireless Bluetooth communication. I gained a lot of hands experience soldering and making a professional looking electrical prototype. Lastly,the design and build of the controller housing was great product design experience that resulted in an aesthetic and functional design.
The Paddle Buddy ended up winning the Best Practical Design Award which would not have been possible without the great work and collaboration between all team members! Exceptional communication was required to ensure all subsystems integrated to form a fully functional prototype that met all of our requirements that were outlined at the start of the project.