The working principle behind our juicer is simply based on compression. Our design is inspired by traditional wine pressing. However, instead of ratcheting manually by ourselves, the pressing mechanism will be automated.
Our group chooses to test our juicer with watermelon as it is a softer fruit with a lot of water content. Based on a research paper, the force required to crush watermelon is about 0.01N/mm^2. Hence after calculation (using the size of the presser we are using), the total force required to crush the watermelon in our set up is around 2500N/250kg. This is a reason why we choose a 400kg actuator for our prototype to crush the fruit.