● Inside shopping malls there are several kiosks which sells candies in bulk. Outside of them, there are still a lot of stores which sell products like this;
● The whole process of selling candy is quite simple, and because of it, has the potential to be automatized. In this way, the selling of this type of product would be possible without any person behind the desk;
● The main problem that comes from the fact that there is no one in the kiosk is that the product stay exposed to the main public, resulting in security and theft issues. Therefore, we must avoid contact between the buyer and the product, only letting the latter available once the payment is complete;
● We don’t want to demand the customers to have an app. That would not be convenient for them;
● We also want some user interface that is attractive, because that would make the client more likely to buy the products.
● First of all, let’s establish exactly the domain of the problem. A vending machine that sells 2 different types of small candies in bulk design to be put inside shopping malls, stores, or any enclosed environment that has easy and constant access to electric power. We will also consider that those environments will have controlled temperature, because usually they have, so there is no risk of the candies melting inside the machine and so jamming the mechanisms.
● The candies will not mix, but it is still important to say that if the owner decides to sell any candy that is generally allergenic, he must put and advise on the machine because of the general proximity and exposure of each candy to the other. We will not be responsible for dealing with that.
● The candies will be stored in a closed and secure container, and must only be available to the customer once he makes the payment. If any attempt of breaking into the machine is detected, an alarm system will be triggered.
● The only method of payment provided by the machine will be via PIX. A PIX QR code will be displayed soon after the customer confirm the order.
● The user interface will consist of the customer’s hand gestures together with a display to properly provide instructions and feedback. A camera will be responsible for recording the user and detecting his hands gestures. In this way, the customer won’t have to have an app and we still have a more dynamic and attractive interface than just buttons.
● On the other hand, the owner of the machine will have an app to make his life much easier. The app will allow him to set the prices of the candies, set his PIX key, see the history of payments, see if a replacement of products is needed, among other functionalities (see Progressive Web App topic).
● If there’s any problem in any step of the process, and the customer get stuck on it, there will be a flaw detection button. The customer can press it to send a message to the server indicating something is wrong (see the Flaw Detection topic).
● The usual flow of operation for the customer will be something like this: (see the Execution Flow Diagram)
● To say to the system you want to buy something you just need to get in front of it and wave your hands;
● To select which product you want you just need to point to it. A LED near the selected product will light up to show to you which product is currently selected;
● Then, another gesture will be needed from the user to put whichever amount of the product he wants. We will use a mechanism, controlled by a servo motor, responsible for taking the candies in batches and moving them to a scale. The scale will then measure the weight and compute the price depending on the selected product; He can do that for multiple types of candies and also how many times we wants for each one of them.
After the user finish his buy, putting whatever amount of the desired products in the scale, another gesture will trigger the payment system;
● If he decides to not buy at the last moment, the product will be moved to a separate compartment through a servo motor (the same that will be used in case the customer pays) for it to be manually restored sometime after;
● If he pays and decides to proceed, the product will be moved through the same servo motor (which will move in a different direction) to a opening which the client has access to;
Figure 1 - Complete structure
Figure 2 - Candy storage container
Figure 3 – Candy selection mechanism
Figure 3 – Candy selection mechanism
Figure 4 - Scale and acceptance and rejection mechanism
Figure 4 - Scale and acceptance and rejection mechanism
Figure 5 - Camera, display and button (user interface)
Figure 6 - Collection nozzle and deposit of rejected candies