Smart Dumbbell Rack and Cleaner

Problem

One of the more frustrating things while at the gym coming across an unorganized dumbbell rack. Weights are all over the place in the wrong spots, and on top of that they're dirty. Our group's prototype set out to solve both of these problems with our smart dumbbell rack and cleaner.

Solution

An LCD screen displays a message that lets users know the proper weight for this particular space on the rack. When the dumbbell is placed on the rack, four load sensors beneath the surface each take a measurement, calculate the average and display the weight on the LCD screen. Allowing for roughly a half-pound of error, if the system detects that this is the correct dumbbell it will initiate the cleaning process. A servo motor, attached to the nozzle of disinfectant spray via a piece of string, turns a specified number of degrees causing it to spray the dumbbell. A PC fan will simultaneously turn on for a ten second period to dry it off.

To get a better idea, check out the video here

note: if the load sensors detect that the incorrect weight has been placed on the rack, the cleaning sequence will not initiate

Materials:

• Arduino Uno - $22.00
• 9V battery (2pcs) - $8.99
• 12V PC fan - $4.78
• LCD screen - $6.51
• Load Resistors (4pcs) - $13.99
• Servo motor - $5.95
• 10k Potentiometer - $0.36
• 220 Ohm Resistor - $0.10
• PNN2222 transistor - $0.42
• Jumpers wires - negligible
• Breadboard - $7.17
• Disinfectant spray - $13.05
• Plywood (2pcs) - $2.68

Total: $86.00

Future Work and Implementation

If we were to work on this idea in the future there are several things we would like to improve upon.

1. In order to get a more even coating of disinfectant on the dumbell, we would add another sprayer of the other side.
2. Since the fan did not work very well a better idea would be to either use cleaner that does not need to be wiped off or build a rig where a rag is ran across the handle to wipe it off.

Cost Analysis

uses our most recent hourly income.

Problems we encountered

1. The scale was very difficult to get to work initially. We first had not realized the centers of the scales parts need to be suspended so that they can bend to get a reading, but even after fixing this, the scale did not work. In the end, it turned out that one of the wires in our circuit was broken, and once it was replaced the scale worked perfectly.
2. The wires that came with the scale were very poor quality and thin, while the board for the scale had quite large holes for them, so there would sometimes not be a connection and the scale would not read properly. We had to solder on thicker wires and tape them to the controller in order to keep it working consistently.
3. Finding a way to spray the disinfectant was a challenge, as we needed to have the servo motor push the spray and release it quickly so that it sprayed, but didn't spray too much. We ended up wrapping the string around the end of the servo and spray top to pull on it for just a moment before resetting.