Below is a picture of the top view of our "main" robotic structure. Here, candy is loaded and spins on a carousel, awaiting user input to be released down a trap door beneath it.
The following paragraphs will highlight the goals of our robot; its structure; previous (less advanced) and potential (more advanced) variations; and the program we will use to effect its physical motions.
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Our Goals
The Mechanics
Our Program
Our Most Recent Updates
Goals: We wished to design a robot that would have a particularly useful function. In addition, we wanted to adhere to these few principles:
Mechanism: After receiving some inspiration from a product on ThinkGeek--a single beverage cooler/dispenser--we decided on making a beverage vending machine. However, after some consultation with Professor Scharstein, we decided to undertake a similar (but slightly more difficult) concept and mechanism: a candy vending machine, with multiple compartments and a rotating carousel that feeds candy (of different types and sizes) to the "customer." We decided to further emulate vending machines by including a coin slot/potential coin release mechanism to charge the customer for their candy. We felt this was central to supporting the United States' "free market" economy.
Below is a picture of the top view of our "main" robotic structure. Here, candy is loaded and spins on a carousel, awaiting user input to be released down a trap door beneath it.
Initially, we wanted our machine to have a coin-release mechanism, but, with time constraints and mechanical limitations, it didn't seem feasible. We also scrapped our idea of a moving structure (one that followed light, à la Star Wars) for the same reason. Instead, we opted for a solid, stationary structure. We used a total of four bump sensors (1 for the coin mechanism, 1 for determining which candy is being vended, and 2 for the user to select their desired candy choice), and for the same reason that many groups did not employ them (imprecision), did not use infared/brightness sensors.
Program: Our machine serves, at its most basic level, to process requests and supply candy. When a specific selection is requested by its unique input of bump sensors (a combination of three taps of A and B on our input pad), if proper payment has been inserted (and sensed by the coin mechanism's bump sensor) the wheel rotates until the compartment that contains the desired candy is positioned over a trap door. The program keeps track of the situation of its compartments with a variable that is updated as the wheel turns. As a bottom bump sensor is triggered every sixth of a turn, a variable is updated, by which the program "knows" which compartment is over the trap door. Once the selected candy is in place, the program releases the trap door and satisfies another customer, before raising the trapdoor and returning to a state of customer readines; however, one or more variables keeps track of which selections have been vended, so that when an item is no longer available, the Handy Board responds appropriately, and when all items are vended the program shuts down.
For a link to our program, please click here.
UPDATE! (1/29/08): For a view of our working robot, and for thoughts on our presentation, please visit this link.
UPDATE! (1/27/08): Below are pictures of our updated (most recent) lego structure, The World's Greatest Candy Vending Machine--Ever v2.0.
Here is a link to pictures of our Lego selves.
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