Carousel

The carousel was designed to optimize the amount of containers that can be stored in the given space of the PreSpice. Wedges were placed between each container with a locking mechanism that allows for removal of containers via the top or out the front of the PreSpice. A gear mechanism was used to rotate the carousel using a stepper motor to allow for precise positioning. Magnets were also placed on top of the flange on the carousel and are paired with a hall effect sensor to allow for closed loop feedback with the positioning system. A magnet with a larger magnetic field is placed in front of one container to act as the main homing position.

Container

One of the reasons an automatic spice dispenser hasn't been developed in the past is due to the difficulty of precisely dispensing granular substances that have different consistencies. The mechanism we designed implements a dispensing wheel that has a slot with a fixed volume of 1/8 tsp. A motor is coupled using two end effectors that allow the motor to rotate the dispensing wheel. The design was built around FDA requirements due to these being the only part of the project in contact with food. For prototyping, the material was limited whereas in an actual product the material would be selected to abide by FDA's regulations for food safe materials. An actual product would also round the inner edges of the container to eliminate sharp corners to abide by FDA's cleanability regulations.

Level Detection

A primary feature that was designed early on was level detection. After interviewing over 100 people, this was a feature that was stressed again and again. This was created using an array of LED's and an array of photo transistors to give a level accuracy precise roughly to 1/6 of the container without any corrections. A flash of light shines through the container and the light intensity is read at each visible photo transistor reading the container level. The preciseness is something that can be improved upon through implementing a relationship between light intensity analog values with precise locations, however, this would be a potential feature to develop.

Spice Detection

To prevent the user from incorrectly entering the name of the spice being replaced, a webcam was implemented into the PreSpice. Computer vision is used to read QR codes located on each spice container, allowing the PreSpice to automatically input new spices into the machine.

End Effector

The size of the device limited the amount of motors that could be used. In order to implement as many containers as possible, we limited our use to a single motor to dispense the spice for all ten containers. This caused a large design challenge when coupling the motor shaft to the dispensing wheels. The end effector was designed such that each tooth has a low probability of coming in contact with another tooth on a separate end effector when meshing. The teeth were given an edge to allow for slippage such that each end effector can fall into place if the alignment is slightly off. On top of this, as the end effector is moved into position, it vibrates back and forth slightly to further reduce the probability of the end effector misaligning.