Introduction: PPAT Team Sarah

Sarah is a woman who lives at The Boston Home and loves watering plants, as it is a very important part of her Scottish culture. She has Multiple Sclerosis and is a power wheelchair user. She was having trouble watering her plants, as she had to juggle a bottle, cap, and cup yet has limited range of motion and ability to grip. On top of this she is legally blind and hard of hearing. This combination resulted in spills, overwatering, and missing her target plant, ultimately leading to embarrassment for Sarah and some clean up for the staff. The watering system we developed utilizes Sarah's chair battery, a fish tank pump, a bottle, and a nozzle to allow Sarah to water her plants with ease and accuracy, ultimately diminishing the amount of spills created.

Step 1: Reservoir

To modify the reservoir appropriately, first bandsaw the bottle at the red line drawn on the left bottle (3" below the lid of the bottle). This opening height allows the pump system to easily fit into the bottle and is the widest we could cut with the bandsaw in the auxiliary IMES room. The opening at the top of the bottle should be 2.75" x 2.75".

Then, drill 2 holes in the bottle on opposite sides of each other:

  1. First for the electrical cord (5/32" drill bit)
  2. Then for the tubing (1/2" drill bit)

Step 2: Bill of Materials

Step 3: Machines Used

Step 4: Pump System and Tubing

Press the clear tubing over the barbed fittings on the pump (see circled in left picture). Then place system into reservoir and thread tubing out of tubing hole and the wire out of the wire hole.

Next, use silicone to create a watertight seal on these holes. To do this, eject silicone around the diameter of the tube and use a gloved finger to create a smooth filet (see second from left picture). Make sure to do this on the inside and outside of both holes and that the surfaces are completely dry when applying silicone.

Following this, the nozzle tubing can be pushed inside of the clear tubing (ensure an overlap of 1" of the two tubes). Then use silicone to create a watertight seal - add a bead of silicone on the edge of the clear tube and use a gloved finger to create a clean filet. Again, make sure that all surfaces are completely dry when applying silicone.

The middle image is of the pump inside of the reservoir with the tubing/wire sealed in. The second from right image is of the silicone that we used (Loctite brand). The right image is the nozzle and nozzle tubing.

Step 5: T-slot Mount

Line up the T-slot nut 1.25" away from the left edge of the bottle such that it is parallel with the side edge (see second from right picture). Use a thin marker to mark holes to drill. Then use a 5/16" drill where you marked on the bottle to create holes to secure the T-slot nut. If drilling is difficult, start with a smaller bit and step up.

Bandsaw the plastic sheet (left rectangle in second from left image) to the thickness of the inner slider of the T-nut. Then use an F drill to drill holes spaced exactly as those of the T-slot nut.

Next, using the screw and washer pictured above, secure the spacer and T-bolt to the water reservoir. The order from outside to inside should be T-slot nut -> spacer -> wall of reservoir -> washer -> bolt head (see right image).

Step 6: Sealing the Reservoir

Add Mouldable Glue (Sugru) to the inside of the mount (around the bolts and washers). See left picture.

Add Silicone to the outside of the nozzle mount (see middle picture).

Add Mouldable Glue to the edge of the cut top of the bottle. Then add more around the outside to ensure the seal is secure.

Make sure that all gaps are filled and all seals are watertight. Let all set for 24 hours.

Step 7: L-bracket Mount and Nozzle Mount

Bandsaw the Aluminum L-bracket to 3" in length (shown on left).

Drill 2 holes 1.25" from the edge of the L-bracket. One should be 0.5" from the bottom of the L bracket and the second should be 1" above the first hole. Then drill these holes through with a 1/4" drill bit.

To mount this to the chair, loosely screw the T-slot nuts onto the drilled holes in the L-bracket and slide into rail of wheel chair. Then, once bracket is in position (8" below top of rail), fully tighten the bolts with an allen wrench.

Step 8: Electrical Components, Battery Wiring, and Switch

Attach the positive (brown) and ground (blue) of the pump into Anderson the positive and ground of two Anderson Power connectors. These Anderson power connectors connect to the positive and ground of the existing switchbox. The switchbox connects from a 24V to 12V DC converter, which connects to the 24V DC power that Sarah has on her chair.

You can add extension cords as necessary. In the topography we laid out, we connected the positive (red) of the power straight into the positive (brown) of the pump. We used an extension wire to connect the ground (blue) of the pump to the ground of the switchbox (blue), while the white extension wire connected the positive of the switchbox (white) to the ground of the power.

When Sarah flips the switch on, this turns on the pump. When she sees the pump grow weak, she can turn off the pump, since the pump cannot operate without water.

Step 9: Decorate!

We used colored tape cutouts to decorate Sarah's chair with grass and flowers - she was very pleased with our design!