Device Overview

When professionals or backcountry enthusiasts need to assess avalanche risk an important metric used in the assessment is snow hardness. For decades snow hardness has been measured using ‘hand-hardness’, a subjective measurement technique that requires the individual to dig a pit and probe the snow wall with their fist and fingers, and estimate how many newtons of force it took to penetrate. Fraser Instruments has been working to replace this standard with SnowPak, a device that can objectively measure the hardness of snow.

SnowPak has gone through several prototype iterations, including 8 rounds of PCB design, fabrication, and assembly. Today the device can comfortably be operated while wearing a glove, and the battery will last an entire season on one charge. It can measure magnetic field (for compass reading), acceleration and angular velocity (to detect usage error), air pressure (to detect altitude), ambient temperature, and of course force.

PCB Development

This is a computer generated image of a PCB that I developed for the SnowPak project (not seen in this image: display connector, LED display, tactile buttons). One of the challenges with this design was meeting the requirment for board size, while also meeting the requirment for button separation and fitting the display in the same footprint.

Another challenge was that during manual assembly was pin shorting on the 9-dof sensos, which was a 24-pin QFN package. All of these challenges were overcome and Fraser Instruments received 10 boards on-time for Winter testing.


First Proof-of-Concept Prototype

This prototype was created in 2-3 weeks. It measured force acting on a button sensor and transmitted the information via bluetooth to a smartphone.

Second Proof-of-Concept

Moving away from using smartphones, this prototype measured force acting on a load-cell and displayed the information on an LED display.

New Zealand Winter Prototype

This prototype was shipped to the other side of the world, just in-time for winter in New Zealand. The data gathered using this prototype was important for setting device requriements for the next prototype interation that would be used in Canada's winter.

Canadian Winter Prototype

Based on feedback from the New Zealand Winter Prototype this prototype was designed to be more compact and have finer measurement resolution.

Final Prototype

The main feedback on the Canadian Winter Prototype was that the display was too difficult to read, both because of text size and lighting issues. The new display is much larger and is readable even in direct sunlight.

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