Rear view camera systems used in automobiles can be fabricated, configured, and installed on wheelchairs so users can increase their field of view. We aim to design a step-by-step guide that permits wheelchair users to have the capability to install a rearview backup system camera on their own wheelchair.
All parts used are available online (For a detailed list of materials and part numbers, see slide 13). The instructables for this design will most likely require access to a machine shop.
Bolding indicates important instructions. Hovering over the Yellow boxes on pictures will provide with additional hints!
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Step 1: Follow GeniusRobotics!
The GENIUS (Girls Exploring New Ideas Using Science) FIRST LEGO League robotics team from the Girl Scouts of Greater Atlanta developed a prototype for a wheelchair backup system on a manual wheelchair for their 2010 Body Forward season. With the help of engineers from CATEA at Georgia Tech, they were able to implement their idea on the electric wheelchairs for two of their friends. The team won the "Make a Difference" Judges' Award at the FIRST World Festival in April 2011 for this project.
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Step 2: What this new wheelchair feature can do for you!
Every wheelchair is different, so the installation and mounting materials will vary.
This feature can improve the quality of life for many wheelchair users. Our first user was weaving in and out of doorways and enjoyed the new freedom that this new feature provided him. Our second user was able to drive in reverse quickly and smoothly into her mother's van. Installing this equipment can benefit similar users in a variety of ways. For safety reasons, this feature will allow users to avoid falling off curbs, sudden drops, or holes that they are not aware of.
Step 3: SAFETY
Make sure there are no exposed wires anywhere once you've installed everything. If necessary, heat shrink can be used to cover up small holes on the connectors.
Before unplugging or plugging in anything, the device should be powered off!
Before you begin to solder very small items follow this procedure:
1. Spread some soldering flux on the components you wish to solder.
2. Gather a bit of solder on the tip of your iron.
3. Touch the components together.
4. Give the components a kiss with the soldering iron. The solder on the tip should transfer to the components.
5. It might be easier to add a small amount of solder to each component, and then use the iron to melt them together.
**Take care not to put too much solder on the tip of the iron, doing so may result in the bridging of two or more components you don't want soldered together.**
Step 4: Suggested Materials
**All of these materials can be ordered from the websites found in the detailed materials list (Slide 13)**
Switch Box (1)
Switch cable (1)
Switch cable jacks (2 ea)
"Hub" box (1)
Fuse holder (1)
Battery plus charger (1)
Power jack (for charger, camera and monitor, 1 each, 3 total)
Power plug (to replace original plugs on camera and monitor, 1 each, 2 total)
Car Camera System
Camera Mount (used on headrest hardware) (1)
Monitor mount (installed on armrest) (1)
Loc-Line ½" tubing
Additional mounting material will be needed depending on the chair
Step 5: Hub Box Preparation
Materials: Hub Box, Drill, (Tape, Ruler and Sharpie can be used to center holes)
a. You will have to drill 5 holes in the Hub box
b. Lay out all of the components inside of the box before drilling anything. This will ensure that everything fits in the way you want.
c. Drilling tips:
i. Make sure the drill bit you are using is smaller than the hexagonal nut and the round housing of the jack. The nut and housing will compress on opposite sides of the hub box to hold the jacks in place.
ii. If you drill the hole too small you can always make it bigger.
iii. When you have your layout, use tape on the outside of the box so that you can easily mark the hole positions.
iv. See the picture of the hub box layout to see each hole’s recommended position. These positions will vary depending on the box’s position on the wheelchair.
v. Note: The charger power jack and switch cable jack should be next to the fuse and the camera jack and monitor jack should be next to each other on the short side of the hub box.
d. Drill 3 holes for the power jacks (one for camera, one for monitor and one for charger). Size: ½ in.
e. Drill the hole for the fuse holder. Size: ½ in.
f. Drill hole for switch cable jack. Size: ¼ in.
g.Once all your holes are drilled, install the jacks with the supplied hex nuts.
Step 6: Soldering Components Inside the Hub Box
Materials you will need: Red and Black Wire, Wire Cutters, Small Screw Driver, Soldering Gun, Solder, Screw Terminal, all the jacks for the hub box, and Velcro.
a. The first thing you will want to do is loosely fit the components in the box. Soldering the circuit before we permanently install or attach any components makes it easier.
b. Measure out lengths of wire needed to connect the components. The lengths may vary, just be sure that you follow the wiring diagram and the components fit easily.
c. Cut the wire and keep track of which wire will connect to what (use labels if needed).
d. All wires should be stranded (not solid-core) and red or black to correspond with positive and negative. Solid-core wire will be too stiff. The solder would break too easily if the wires were moved around.
e. Once the wires are cut, they should be stripped on both ends, about 1/4 to 1/2 inches.
f. Solder should be applied on both ends of the wires and on each connector’s tab, depending on where the wire will be connected (See picture to see hoe the small wires should be prepared).
g. Remove the components from the box. Starting from one end of the circuit, begin soldering. Remember that the terminal block connections are not soldered, they are screwed in. With a terminal block, the battery can be replaced with a small screwdriver.
USE CIRCUIT DIAGRAM PICTURE TO SEE WHICH WIRES GO WHERE, WHAT COLOR THEY SHOULD BE, AND HOW MANY ARE NEEDED!
h. Since solder has already been applied to each end of the wires and the connection tabs, the soldering tip can just be used to fuse the solder together.
i. Note: Pay extra close attention to the power jacks, because only the charger’s power jack will use all 3 connections or tabs. The other power jacks will not use one of the tabs (labeled "1" on the circuit diagram; it's the small tab on the inside/top).
j. The battery should be connected to the screw terminal. The red thick wire will be screwed into one terminal, and the black thick wire in another.
k. A multimeter can be used periodically to check the circuit. There should be very little resistance between any components that are connected.
l. Once everything is connected and the circuit is complete, connect the power jacks and fuse holder to the box using the hex nuts (provided with the corresponding part).
m. The battery and the terminal block should still be loose at this point.
n. Place the battery and terminal block in their respective positions inside the box. Place soft foam around the terminal and battery to keep them in position inside the box. This step could be done in multiple ways with glue, double sided tape, Velcro, etc. Just be sure the battery can be changed.
Step 7: Preparation of Switch Box
Materials: 1 switch box, 1 latch switch with large surface area (depends on strength of user), 1 switch cable jack (mini phone jack connector), 1 switch cable, wire cutters
a. Drill hole for switch in the top of the switch box. (placement varies based on wheelchair and user's preferences)
Size: ½ inch
b. Drill hole to mount the cable jack on short side of switch box (varies based on where this box will be placed on the wheelchair). Size: ¼ inch
c. Screw cable jack and switch in place (see picture).
d. Cut switch wires so they will fit inside box. Recommended length: 4 in.
e. Strip end of each wire, and apply a small amount of solder.
f. Apply a small amount of solder to the 2 tabs on the cable jack.
g. Use soldering tip to attach each wire to a tab (order is not important).
h. Note: The circuit can be tested with a multimeter. Check for connection when switch is on, and for no connection when switch is off.
i. Screw switch box top on with screws provided with switch box.
j. Plug in switch cable.
Step 8: Rewiring Cables
Materials: Extension cable that came with the monitor (plugs into red component), extension cable that came with the camera (plugs into black component), soldering equipment, power plugs, wire cutter, wire strippers, small pliers
a. The extension cables (shown in the figure on the right) should be rewired with standard power plugs to connect with the standard power jacks used on the hub box.
b. Plug the extension cable for the monitor into the monitor and the extension cable for the camera into the camera. Don't cut these ends. Cut the connectors off of the opposite ends which are not plugged in.
c. Strip these large wires about 1 inch while leaving the small wires intact.
d. Note: Don't strip these too much. If you notice in the pictures, the power plug has silver tabs that need to be clamped down on the thick wire, so the lengths of the thick and thin wires matter, and should line up with the connector.
e. There will be a red wire and a small black wire on the inside of the thick wire. They will be soldered to specific tabs on the power plug.
f. Unscrew the power plug cap (See Part 2 in this picture).
g. This black power plug cap should be slipped over the thick wire in the correct direction! After you've finished soldering, you will screw the cap back on. DON'T FORGET THIS STEP or you'll have to remove all of the solder and do it again.
h. The small red wire and black wire should be stripped to the appropriate lengths. The wires should reach their connection points (red should be soldered inside a small opening and black should be soldered along silver tab extension on the bottom of the power plug). (See the caption in Part 3 of the picture for more details)
i. The order is important here. Positive/red should touch the positive tab on the connector, and negative/black should touch the negative tab on the connector. However, they should not in anyway be touching each other. So, don't use too much solder. Use a multimeter to check this connection! (See the caption in Part 3 of the picture for more details)
j. After soldering and checking the connection, shut the silver clamps on the thick black wire (See Part 1 in this picture). Use pliers for this. Make sure it's tight, so that if anything pulls on the wire, it does not put any stress on the connections that have just been soldered.
k. Screw black cap on.
Step 9: Mounting Suggestions for Camera (varies with every wheelchair)
Materials: Mount for back of wheelchair, Camera with attachment (see picture), drill, screws
a. Drill two holes in camera mount to attach camera attachment
b. Add screws to secure attachment
c. Attach camera on metal attachment that has just been screwed on the mount.
d. Install mount and camera on chair
e. Adjust angle according to user's preferences
Step 10: Mounting Suggestions for Monitor (varies with every wheelchair)
**Note: This will vary from chair to chair. This chair had a removable tray, so the mount had to be detachable, so the monitor and wires wouldn’t block the tray transitions.
Materials: Monitor, Loc-line, extension cables for monitor, Figure-8 clamp, zip ties, 2-part Epoxy
a. Loc-line should be used for mounting the monitor. It is sturdy, but people will still have the ability to move the monitor out of the way.
b. The monitor was secured to the Loc-line using 2-part Epoxy.
c. The Loc-Line will extend downward to the arm rest.
d. The wires from the monitor can be fed through the Loc-line if it's big enough or wrapped around the Loc-line (Zip ties can be used to get any excess wires out of the way).
e. The Loc-Line is attached to the chair under the arm rest (using the pole under the arm rest) with a Figure-8 clamp.
Step 11: Final Assembly
Here are two examples of successful installations.
a. Use black zip ties to make sure the wires are out of the way. Be careful where the tie ends, because they are sharp.
b. Use Velcro to attach the Hub Box to the chair.
c. Double sided tape can be used the attach the switch box to an armrest.
d. Labels can be added on the Hub Box, so it is clear which wire goes where.
e. Make sure no wires are exposed. If some are, heat shrink can be used.
f. Plug everything into the Hub Box, and try it out! (Note: Connections should be checked throughout the whole process to make sure nothing came loose!)
g. Test out the battery charger. Note: When charging, the monitor and camera will not work.
h. Before unplugging or plugging in anything, the device should be powered off!
i. If someone was hired to install this feature, make sure the client/user knows how to change the fuse and how to properly change the battery!
Step 12: Alternative Switch Option
If the user's hand strength is minimal, a toggle switch might be more practical.
Make sure switch box is sealed, so it is not exposed to water.
Step 13: Alternative Mounting Options
This user had a custom installation, because she uses a removable tray throughout the day.
If the head rest tube is round instead of square, a different mounting piece will be needed (see picture), but the installation is the same.
Step 14: Detailed Bill of Materials for Most Items UsedBill of Materials
(SWITCH PB SPST SEALED IP67 RED)
Switch cable (1):
(CABLE STEREO 3.5MM M-M 1.5M)
Switch cable jacks (2 ea):
(CONN JACK MINI PHONE 2COND)
"Hub" box (1):
(BOX ABS FR BLACK 4.8X3.7X1.2")
Switch Box (1):
(Electronics Enclosure Project Box 2.51" x 1.73" x 1.25" (3 pack))
Fuse holder (1):
(FUSEHOLDER 5X20MM HIPRO PANEL MT)
Fuse (1): for 3AG, 5 x 20mm, or 2AG Fuses 345 Series
Battery with charger (1):
(Li-Ion 18650 Battery: 11.1 V 2400mah (26.6Wh) battery module with Protection IC + 0.8A Smart Charger (2.16))
Power jack (for charger, camera and monitor, 3 ea):
(CONN PWR JCK 2.0 X 6.6MM PNL MNT)
Power plug for camera and monitor (2 ea):
(CONN 2.1MM FEMALE PLUG 5.5MM OUT)
Model # RVS-770617N
Mounting hardware (varies for every user)
Camera Mount to headrest (option one)
Therafin Headrest mounting hardware part no. 32910B
http://www.therafin.com/pdf/64-76.pdf (under PDF Documents, page 64-76, on last page)
Camera Mount to headrest (option two)
7/16"Collar to Fixed mount Base: part 16160
Monitor mount: Loc-Line to armrest tube
http://www.therafin.com/controlaccessories.htm (Figure 8 adaptor clamps)
Figure-8 Clamp, 3/4" to 7/ 8", Black #32310B
Loc-Line ½" tubing: Black : part 51801
2 part epoxy to attach Loc-line to monitor
Step 15: Special Thanks!
We would like to give a special thanks to:
Girl Scouts of Greater Atlanta
Rear View Safety
Dr. Stephen Sprigle
Step 16: Questions?If you have any questions about how to fabricate, configure, and/or install a Backup System Camera onto a Wheelchair or about the parts listed in this instructable, please contact:
Dr. Steven Sprigle at firstname.lastname@example.org
We hope you've enjoyed this instructable! If you decide to add this feature on your wheelchair, please do post a picture or two! We'd love to see them!
More Contact Information (if needed):
Georgia Institute of Technology, College of Architecture
490 Tenth Street, NW
Atlanta, Georgia 30332-0156
Phone 404-894-4960 (V/TTY)