Tasks that seem obvious for us can be a real challenge for a visually impaired person. Checking if the water bowl of their guiding dog is empty was a time-consuming and physically demanding job for visually impaired. As the guiding dog can’t bark, even when he’s hungry or thirsty, his drinking bowl was sometimes empty for some time. Our solution is a balance system that’s being put under the drinking bowl. When the weight of the water in the bowl is too low a switch is turned on. This triggers a signalisation unit (solar powered flashing light) that immediately draws the attention of the user and impels him to fill the water bowl. To make the system as efficient as possible we offer the possibility to adjust the contact to the right weight in a very user-friendly way. This makes it possible to trigger the signalisation as required, for example when the water level is about 1cm in the drinking bowl, what is too little for the dog to still be able to drink properly.
Step 1: Materials and Tools
- PU foam
- PS plate, thickness 2mm
- 3D cad program
- CNC milling machine
- Thermoform machine
- drill D4mm
The spring mechanisme
- 2x wheel cover holder D6mm (Gforce)
- carbon bar D6mm
- 4x specific clothespin (Action)
The controllable switch
- threaded rod M4
- roundel D20,d5mm
- electrical wire, usb winder
- tin solder
- MDF, thickness 5mm
- M4 nut
- Expoxy glue
- soldering iron
- drill D5mm
The signalisation unit
- signalisation unit (bicycle light)
- tin solder
- Epoxy glue
- litlle hook and magnet
- screwdriver to open the singalistion unit
- soldering iron
- 2x roundel D12,d7mm
- 2x M4 nut
- 2x M4 wrench or 2x forceps
Step 2: The Shell
A Make a 3D cad model of the shell, make shure your dog drinking bowl fits. You can make the top a little concave, so the drinking bowl will center itself. Or you can use the already made 3D cad model / STL file shown below.
B Make a PU foam mold of the shell, based on the 3D cad model / STL file, using the CNC milling machine.
C Use the PU foam mold from 'B' to thermoform the final shell. As material we used PS, because of the good thermform properties.
D Cut out the thermoformed shell at a height of 30mm with the Dremel. Also cut out a recess of approximately 120mm long, 20mm heigh.
E Drill a hole (D4mm) in the center of the shell.
As alternative you can make a shell from wood, carboard or plastic. Just make shure that the shell has a diameter of approximately 200mm and heigt of 30mm. Provide the shell of a recess, as the above pictures are showing.
Step 3: The Spring System
A Saw the carbon bar at length (150mm) with the Dremel.
B Make a 5mm hole in the center of the carbon bar with the Dremel.
C Make two gaps of 25mm, at each side of the carbon bar, perfectly outlined to each other and to the center hole made in 'B'.
D Slide the 2 cothespins (Action) into the the gap. Do this at both sides of the carbon bar.
E Mount the wheel cover holders (Gforce) to fix the cothespins. Do this at both sides of the carbon bar.
As alternative for the wheel cover holders you can use everything that can clench the gap, for example: straps, rope,...
Step 4: The Adjustable Switch
A Glue the roundel (D12,d7mm) to the carbon bar with Epoxy glue, concentric and parallel with the drilled hole in the bar, without being in contact with the carbon bar.
B Solder one wire of the usb winder to the glued roundel from 'A'.
C Saw the threaded rod at length (27mm) with the Dremel.
D Solder the other wire (same side) of the usb winder to one end of the threaded rod from 'C'.
E Make a adjusting wheel (D85mm) with a thikness between 2-5mm. You can use wood, plasitc, etc. , cutting it out with a figure saw or Dremel. Drill a hole (d5mm) in the center of the wheel. Glue the M4 nut in the center hole of the wheel with Epoxy.
F Screw the adjusting wheel on the threaded rod made in 'D'.
Step 5: The Signalisation Unit
A Hack a signalisation unit: Open the signalisation unit. Interrupt a connection between the power source and the signalition. Solder the other two ends of the USB winder each to one side of the interruption you made.
B You can provide the signalistion unit with a litle hook or magnet, so you can fix it somewhere.
For the singalistion unit you can use any light or a buzzer, as required. We used a solar powered bicycle light, so the user wouldn't have to chance batteries.
Step 6: Assembly and Setting
A Put the threaded rod with adjusting wheel through the center hole of the carbon bar. Screw a M4 nut about 10mm on the threaded rod and place the roundel (D12,d6mm) on top of the nut.
B Place the shell on top of the roundel, the threaded rod through the center hole of the shell.
C Place the second roudel (D12,d7mm) on the threaded rod. Srew another M4 nut on to fix it, firmly tighten.
D You can set the signalistion weight by first placing the drinking bowl on top with the desired amount of water, then turning the adjusting wheel until the signalisation is triggered.