About the project:
This project provides wheelchair users with limited dexterity a device to train and reward their service dogs easily and conveniently.
This project was undertaken in cooperation with PADS (Pacific Assistance Dog Society), a non-profit organization in Vancouver, BC that breeds, raises, trains and supports certified assistance dogs, partnering them with people living with disabilities. Assistance dogs at PADS and many other organizations are trained using the clicker method. Good behaviors and successful commands are marked with a distinctive noise from a handheld clicker, followed by a dog treat. Many wheelchair users who are provided with service dogs find it difficult to use a clicker and deliver treats due to reduced mobility or dexterity. There is a need for an easy-to-use wheelchair-mounted device that can make a clicking noise and dispense treats. Currently, all available products are either unsuitable for this task, or prohibitively expensive.
A 3D-printable device was designed to simultaneously deliver treats and actuate a typical handheld clicker using a simple pushing motion. It can be mounted on the side of a wheelchair using a commonly-available type of mounting bar and bracket. The device is made of exclusively 3D printed parts in order to eliminate any potential difficulties sourcing components, and does not require any electronics. It is both easy and affordable to replicate.
Short video demo of the finished product being used at PADS: https://www.youtube.com/watch?v=7nEjaSM5ihQ
Close-up video of the device being used: https://www.youtube.com/watch?v=3KIXZ9USlOU
Download all part files. There are 9 parts total, including an optional mounting spacer. Two versions of the hopper are available. "TreatDispenser_hopper-mount_holes" has holes for mounting (2 x 1/4", 1" apart), and "TreatDispenser_hopper-no_holes" does not. Only one is necessary, depending on your preference.
Create g-code files from the STL part files with whatever 3D slicing software you prefer, and 3D print all parts. 3D printing quality settings shouldn't matter much, though a fill of ~20% or higher is recommended for strength. None of the parts exceed a length or width of 150 mm, and should fit most 3D printer beds. The device was originally prototyped using 1.75 mm PLA filament and a Tinkerine DittoPro 3D printer, but other filament types and 3D printers should work just as well.
1. Attach the "tray" to the "frontplate" by sliding it into the angled slots. This may require some force, or possibly even filing/sanding of the parts, depending on print quality. It is intended to be a tight and permanent press-fit.
2. Lay the "arm" on a flat surface with the open end of the round slot facing upward. Slide the "clickpeg" into the slot, so that the peg extends outward from the midline of the "arm."
3. Lay the "backplate" on a flat surface. Place the "arm" on top of it in the proper orientation (the holes should line up), and put the "pin" through the lower hole on the "arm," and into the corresponding hole in the "backplate." It should fit easily.
4. Attach the "frontplate" to the "backplate." Begin by pressing the pieces together at the top left corner, then continuing around the edge of the "frontplate," ensuring that the "pin" lines up properly with the corresponding hole in the "frontplate." When the "frontplate" is in position, it should rest flush with the walls of the "backplate."
5. Move the assembly into an upright position, and attach the "hopper" to the "backplate" by pressing the pieces together around the edges.
6. Put the "lid" into the loading hole at the top of the "hopper." The treat dispenser is now fully assembled.
Optional: Place a hand held clicker in the slot at the left of the assembly. It should slide all the way to the bottom and fit snugly in place.
Remove the "hopper" from the "backplate." The two 1/4" holes in the "hopper" have a center-to-center distance of 1", and are intended to align with a commonly-available wheelchair mounting bar and bracket. If necessary, the "mount_spacer" can be placed between the mounting bracket and the "hopper" to avoid collisions with other bolts in the mounting bracket. Mount the "hopper" on the wheelchair anywhere within easy reach of both the wheelchair user and the assistance dog. Once mounted, the "backplate" can be reattached to the "hopper," and the treat dispenser is ready for use.