Welcome back to another blog post where we get to the nuts and bolts of our CanSat project by exploring the design choices, material selection and 3D printing process involved in bringing our CanSat to life.
Design decoded​
Imagine our CanSat tumbling down from 200 m altitude at a speed of 15 m per second; we want it to be able to capture multiple image pairs during its descent that we can later use to create our depth map. This is where our scientific mission really begins thanks to an innovative design of two unfolding camera arms that will give our can a birds-eye view of the terrain below.
But how exactly do these camera arms work? Well, the answer lies in a trio of tactics: first up are the screws, which act like hinges helping the arms to smoothly swing open and lock in place. These screws also play a pivotal role in holding the entire assembly firm and steady, so that the cameras have a stable and even base to capture from.
Next, we needed to make sure the arms pop open at the right moment without any hitches and this is where the springs and elastic bands come in. Initially, we thought about using the parachute lines, but then we learned they could break off under the sheer force of the parachute pull. So, we integrated a spring mechanism that exerts a force to swing the arms open as soon as the can is ejected from the launch rocket. Simultaneously, a simple elastic band works wonders, effortlessly snapping the arms into their designated positions.
And last but not least, let’s not forget about the brains of the operation - the electronics, including the Raspberry Pis, battery, sensors, communication system and other electronic modules that will turn our can into a working mini satellite. We nestled these snugly in a middle, modular piece that slides right into the outer can in a setup that is not just neat - vital when space is so tight - but also very practical, allowing us easy access to tweak or fix anything.
Bringing the can to life​
Let’s take a closer look at the 3D printing process. We used FDM (Fused Deposition Modeling) 3D printing, which builds up our can layer-by-layer.
At its core, FDM 3D printing blends digital design in 3D modelling software such as Fusion 360 to create a design template for print, and material science. A 3D printer guides filament material through a heated extruder. As this filament lays down onto the build platform, it begins to cool and solidify. With each pass of the extruder, another layer is added, slowly stacking up to reveal a physical object crafted from digital blueprints.
Material matters​
The choice of filament in this printing process is crucial. It's not just about picking a colour or a texture. The material properties - how flexible or sturdy, how resistant to heat or stress - can dictate the success of the final component, influencing everything from the CanSat's durability to its functionality. But with the sheer variety of 3D printing filaments available, each boasting unique characteristics and specs, the process of selecting the right one needs careful thought and consideration. So, for our camera arms we championed PET-CF - a fusion of PET (polyethylene terephthalate) and carbon fibre (CF) as it boasts an incredible resistance to bending out of shape or snapping under pressure, and for the inner and outer can we turned to PLA (polylactic acid)-CF as it’s easy to print and biodegradable yet strong.
A 3D pivot​
But even with careful material selection, in our initial tests, we encountered a real challenge: our can wasn't holding up. After a few parachute drops, it was splitting in half - a clear sign we needed to rethink our approach to its durability. The secret to 3D-printed parts' strength, we found, lies in how the layers are bonded together. Think of it as the grain in wood; aligning it correctly can significantly impact strength. Our solution? We changed our printing strategy to lay the can on its side. This adjustment meant the layers were positioned to better resist the forces encountered during drop tests. By reorienting the print direction, we significantly improved the can’s structural integrity. Now, it not only withstands the tests but is primed for its real-world missions.