Looks to be a bit slow on the forums, so I'd figure I'd post this chair I did recently...

This is fairly complex powerchair we recently configured for a veteran with C4 quadriplegia for his first chair. It is a sip-n-puff operated TDX SR with a Motion Concepts UltraLow system.



The specs..

Invacare TDX SR Powerbase
- MK6 Display w/ Sip-n-Puff Digital Interface
- MK6 Wireless Mouse Infrared Module
- PACM6 Proportional Attendant Control

Motion Concepts TRX Ultra Low 55 Deg Power Tilt System
- 17.25" Seat-To-Floor
- 17" Seat Width
- 18" Seat Depth
- LNX Power Center Mount Legrests
- Large Individual Footplates (6"Wx11.5"D)
- 16"H MaTRx PB Elite Back w/ Offset Laterals
- Ergonomic Arm Trough/Hand Pads w/ Multi-Axis Mounting Hardware
- 10" Stealth Comfort Plus Headrest

Custom Modifications
- Custom Mounted Egg Switches In Headrest (Mode & Drive Select)
- Custom Sip-n-Puff Mount
- Custom "Double Lip Switch" for Computer Access
- Custom Elbow Stops for Arm troughs
- Custom Drink Aid Holder

These are the new Motion Concepts LNX power center mount legrests which are also available on the new Invacare FDX. They don't add as much length to the chair as the previous Motion power center mounts, and this design allows the footplates to be spaced farther apart (The footplates were originally mounted right next to one another). This is done by removing spacers inside the back of the footplate and relocating them outside on the hinge post between the center stalk and footplate. The additional space between the footplates may help prevent "frogging" and may provide enough room for a Hoyer-type lift to fit in between...



I used 1/2" hollow ABS rod, Loc-Line modular hose, and a Gatlin swingaway mount to fabricate the custom sip-n-puff system. We ordered a commercially available unit that worked pretty well, but the veteran liked the way the ABS rod was angled because it allowed him to scratch his face or push his glasses up his nose if they slid down.

A drink aid holder was fabricated and clamped to the backrest spreader bar.




The switch interface box on the backrest allows the switches mounted in the headrest to be easily disconnected so that the headrest can be removed for transfers. I also wired in an input jack for an additional mode/reset switch for a caregiver at the back of the chair. Inside the box, all the wires from the input jacks are combined into a single cable with a stereo plug which is routed to the MK6 display (i.e. no "Y cable or extension cables are used). Less connectors means less chance of things getting disconnected and harnesses can be routed more-cleanly. A quad push button was mounted to the underside of the box so that an attendant can easily access it, but the buttons are in a protected location.

Part of my job is to make sure that when everything comes together, the usability of the powerchair will be optimal for the specific individual who receives it, it will be as reliable as possible, and that any foreseeable problems are prevented. As an OT/ATP, my job is to match the appropriate assistive technology to the needs of each end user to maximize function (i.e I need to make sure everything works well together).

Of course, these products are not produced in large volumes and things can and do go wrong. The powerchair is operated using a total of 8 switches--all of which can be activated using using little to no head movement...

A sip-n-puff unit actually accepts 4 different types of directional switch input

Hard Puff: Forward
Soft Puff: Right
Soft Sip: Left
Hard Sip: Reverse

How does turn right and still go straight? Because the hard puff is set for "latch mode". Latch mode is like cruise control which allows the chair to continue moving forward even though the user is no longer blowing into the straw. While it is moving, a soft sip or soft puff will allow the user to make minor steering corrections.

One of the most hazardous situations that can occur when learning to drive is being able to turn right while traveling at speed. If the chair is rolling forward in latched mode and the user's puff is too hard, the chair will continue going straight because a soft puff wasn't detected. I've done it myself and it can be a helpless feeling.

Knowing that this chair was for someone who was newly injured, I spec'd out the LNX power center mounts to reduce the footprint and I ordered the large individual footplates (11.5" long). The LNX legrests are very durable and can absorb significant impacts. While the longer footplate increases the turning radius slightly, they also provide full foot protection. My rationale for selecting this combination proved to be right on the money the first time he drove the new chair It was slightly faster than loaner TDX SP he had been using. The adrenaline surge brought on by driving a better, faster, chair resulted in too hard a puff for a right turn at the end of a hallway. As the indentations in the wall indicate, the chair never did turn right...



Fortunately, between the length of the footplates and the durability of the center mount legrests, he didn't have a scratch.

I was disappointed to see this on Invacare's website last week...



   
On August 12, I was able to order two of the remaining wireless mouse/IR modules off-chair for a couple of future TDX's that I'm about to order.   Good thing, because the wireless/IR module no longer appears in the online configurator.  I also noticed this change to the TDX SP order form today...

[INDENT][INDENT]RFM Wireless (RF) Mouse Only Module ...................... $750.00
RFM will be available in September, 2010. Allows wireless
computer mouse operation through the driver control. Includes
two button stereo switch (with hook/loop mount) for mouse
clicks. Not compatible with SPJ+ joysticks.[/INDENT][/INDENT]

Have you shortened the tubing to a bare minimum and made sure there are no leaks at the fittings?

The infrared transmitter that attaches to the front of the MPJ/MK6 Display and connects to the MK6 Wireless Mouse/Infrared Module on the back of the chair is designed for use with home audio/video systems.  It comes with a very thin two conductor cable which is 10 feet long and fairly fragile.  How to route the cable so that it will not be vulnerable to damage and bundling the excess cable so that it is out of the way and does not stress the cable at the plug has proven to be a challenge.  I discovered a simple solution earlier this week.  If a small hole is drilled in the joystick tube, the excess cable can be threaded inside where it will be protected and out of the way.  I placed a piece of heat shrink tubing over the hole to keep the cable in place...



I used dual Tash Microlight switches on an ABS bracket for the mode and left click functions.  The Microlight is usually very sensitive, so I inserted a piece of spring from a ball point pen under the lever of the Microlight that will be used for the "mode" function.  The modified Microlight requires roughly the same effort as an egg switch to press while the unmodified Microlight next to it can be double clicked easily (much like a standard mouse).

When I saw a prototype last year in Elyria, I asked and was told "no way".

While I was strolling down the plumbing aisle of my local Lowes Home Improvement store, I came across an assortment of J-Hook Pipe Hangers.  



http://www.lowes.com/pd_300611-33599-AV300611_0_.htm
I've been spending considerable time lately working on various ways to route the vent circuits (tubing) on the backs of powerchairs ensuring that there are no excess loops of tubing hanging out and that the portion closest to the end user's tracheostomy site is secure.  These ABS plastic hooks, which are normally used to hold PVC drain pipe, seemed like they might hold promise.  Sure enough, they did.  The double hook holder was constructed from two 1" hooks trimmed down, Super Glued together, and secured with a 4-40 screw.  I inserted it into a bolt-on push handle receiver for a rigid frame wheelchair.


Larger J-hooks were used to secure the remainder of the circuit...

I'm willing to bet that I make some of the same routine tweaks that you do, and that you and I are not alone.

Have you ever wondered...
How the standard program settings were determined?
Why, throughout the ages, they haven't changed?
On Formula CG chairs, why they don't label Drive 4 "SEATING" instead of "RAMPS_CURBS"? (After all someone would need a programmer to turn off "No Driving" in order to access that standard program).

ditto on jakeyboy's recommendation.

Per definition, "Traction" is...



A few years ago, I attended one of the first training seminars when they released MK6 electronics.  I still remember the Invacare technician going through the list of parameters and definitions for MK6.  When "Traction" came up, his response was...



For some reason, I chose to listen to his advice.  I have never played with it and have never felt the need to.

What gets me is why they named it something just about anyone who plugs in a programmer is going to assume they know what it is and, more-importantly, is probably going to want to adjust.

jakeyboy, feel free to correct me, but to my knowledge, there's no switches or sensors to sense whether the cover is on.  It still could be still be possible that you have a loose connection someplace but managed to re-establish a circuit when everything was bundled back up.

You may want to try moving the harnesses around a little to see if an error message can be triggered.

About the same footprint as Permobil's C300.  It looks a little sleeker up close.

A fair amount of the Formula CG tilt system is actually manufactured by Motion Concepts.

John,

I've probably learned more about how vents are interfaced with powerchairs by reading various posts you've made on the internet.

From a cost/benefit standpoint, how beneficial do you think it is to have a 12 volt accessory port wired into the main set of 22NF's to have as a backup with a three 22NF tray (most veterans I see use an LTV series style vent).

Have you heard of any issues powering the LTV off of a 22NF battery?  It appears Pulmonetics only approves their batteries, but the only downside I see with a 22NF battery is that they makes less money.

Do you know how long an LTV series vent will run off a chair with two Group 24 batteries using a 12 volt accessory port (converter)?  Sometimes, I have to reconfigure powerchairs which were not originally intended to power a vent.

Thanks for any input.

Loews, Home Depot, Sears Hardware, or just about any home improvement/hardware store.  The left one is a gray plastic conduit clamp with one end Dremel'd off and reformed slightly with a heat gun...




The other one was fabricated out of 3/4"x1/8" aluminum strapping which I wet sanded and covered with heat shrink tubing.

Some of you may have seen this posted on another forum, but I am posting it here as well because there is no such thing as self-plagiarization...

This is probably the most-complex powerchair I have ever done. It was configured for the needs of a veteran with high quadriplegia who was ventilator dependent, with no movement in any of his extremities, and had only limited ability to turn his head.

I started with an Invacare TDX SR powerbase equipped with a 3 22NF battery tray (the extra battery powers the vent). The TDX base was shipped to Motion Concepts for installation of an 18x19 UltraLow power seating system with the following features:

- 55 degrees tilt
- 174 degrees power recline with high pivot mechanical sheer reduction
- Pivot Plus power elevating legrests
- Articulating Compact Vent Tray
- 18.5" Seat-To-Floor
- 18"H MaTRx Contour Back
- Ergonomic Arm Troughs with Multiaxis Mounting Hardware
- Swingaway Lateral Thigh Supports
- Stealth TWB Lateral Supports

Here is the chair when it arrived.



My initial objectives were to clean up the wiring, relocate the attendant control, install the alternative driving system, and make space for the vent "circuit" (tubing).

The chair is operated using an ASL109 Stealth Ultra Sip-N-Puff Head Array. With this system, the sip-n-puff straw is used to drive the chair forward or backward and proximity switches embedded in the lateral headrest pads are used to turn the chair left and right. The sip-n-puff mount was custom fabricated out of Loc-Line modular hose and relocated from the headrest to the backrest to allow the headrest to be removed and the sip-n-puff system swung out of the way for transfers.

To switch between driving profiles, access the power seating, or operate the infrared/mouse emulation features I fabricated a "double lip" switch using two roller lever switches to replace the single push button "lip switch" that ASL provides with the system.



I ordered the chair with Stealth's TWB laterals, but I have not had good success using them to achieve stable positioning without excess pressure. I ended up replacing them with fixed offset laterals from a MaTRx PB Elite back. Believe it or not, they could be bolted on using existing holes.



To keep the his arms from coming out of the arm troughs when tilting, I modified the Motion Concepts Ergonomic Arm Troughs with custom elbow stops made from aluminum strapping, ABS plastic and Roho Adaptor cells. They mount in the channels underneath the arm trough and will not interfere with flipping the armrests back. I don't understand why Motion Concepts or Otto Bock haven't came out with something similar themselves since it solves a common problem, is simple, and seems to be such an obvious solution.



I was pleased with how cleanly I was able re-reroute the electronics harnesses, but I didn't realize I would face almost as difficult a challenge routing the vent circuit. The amount of tubing is excessively long for a powerchair and can not be trimmed to length. I was especially concerned about it getting snagged on something in the surrounding environment or getting crushed in the power seating system. I fabricated the following system of hooks...



Motion Concepts has an optional 12 volt accessory power supply.  I reversed the direction of the receptacle to point toward the rear so the vent could be powered off the pair of 22NF's which normally provide power to the chair.  I did not order this option with the vent in mind, but it was a good thing I did because the the third 22NF was not yet operational during the week I saw him to complete fitting and training...


Here are pics of the end result...


These chairs take a lot of work, but it is rewarding when the end user is able to use it successfully and you know your efforts played a major role.

Here are some hastily taken pics of Invacare's new cantilevered armrests (desk length).



They are by far the sturdiest armrests Invacare has ever put on a powerchair.  They flip up easily and clear the back without difficulty.  

There should be no problem adjusting them when the new curved back or the new Contoura back are used.  

They may limit the ability to mount a Personal Back or other custom back on the back posts.  For example, the upper and lower clamps of a Personal Back will fit on either side of armrest bracket.  Because there is just enough room for the bracket to fit in between the upper and lower clamps, however, it may not be possible to attain the optimal back height and arm pad height simultaneously.  

Also, while they are sturdy to push off of, they do not lock down.

Overall, a very nice option.