Oct 19 2016 - Putting Force Sensors inside my prosthetic socket.

I have been building a sensor system to show the forces between my prosthetic socket and my stump.

I am using some force resistive pads as sensors. They change resistance as the force on them changes. They can measure from 0 to about 20 kilograms of force.
I sense the change in resistance with an Arduino computer, and then use the Arduino to vary the power to 3 LED lights.
The LED lights are two color ones. Red and Green. I am using Green to show that things are on and working, and the red to show the pressure.

It looks like this.

I put the 3 force sensors that I had, and their wiring,  in-between two pieces of thin hard, clear plastic. I put the wiring for the LED's, and the LED's  in similar plastic. I then connected the two pieces of plastic so that when the plastic with the sensors is inserted into the socket, the LED's will always be in the same spot on the outside of the socket, where the sensors are on the inside of the socket.

 I tested everything.

Then I slipped the sensors into the front of my socket. The lower sensor should be down by the end of my stump, and the top sensor at the top of my socket. The middle sensor is about where I have my inflatable air bladders.
Then I test if it all works, by standing in front of the mirror.

Then I inflated the air bladders.

All my walking with the sensors never lit the bottom LED. This means there was never any pressure on the lower part of my stump.  I don't know why I need lights to tell me that. Pain usually does that job. :-)

To be really effective, I would need about 50 sensors in the socket, and a way of recording the forces, so it could be played back and studied. Tomorrow I go to visit my prosthistist. I will show him my invention.
He and I need to talk lots about me going away for a few months to America. I fear it will be on my old Mauch Knee. :-(  I am spoiled from wearing the Total Knee 2000.

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Sep 30 2016 - Another new socket...No.10

I have been wearing my latest socket quite a bit. It is very uncomfortable, but...
IT DOES NOT CAUSE PAIN!!!!

It is hard to explain the importance of that to me.

The end of my stump that is farthest from the body center, is called the "distal" end. Actually, distal is the farthest of anything from the center of the body. Proximal is the end closest to the center of the body.
This is Doctor talk, but does help is being precise about body directions.

The problems of my stump are mostly at the distal end. Pressure on the distal end is very painful. If the skin on the stump is pulled toward the hip (Proximaly), it puts pressure on the distal end. So when donning (that is medical talk for "putting on")  a socket, the friction force on the skin, toward the proximal end of the stump, causes skin to pull and puts pressure on the distal end. Of course this is also a factor when my entire body weight is on the stump inside the socket.

This latest socket is kind of weird. My stump is about 35 cm long (14 in). This socket is build so that the most distal half of my stump is not in contact with the socket. The distal end just floats around like a clanger in a bell. This means that 100% of by body weight is supported on just 15 cm (6 in) of the proximal end of the stump. By putting all the weight up high on my thigh fat, it makes the pain on the distal end zero. Having all the weight concentrated is a small area is not comfortable. Like wearing shoes that are way to small.

The big problem with having the distal end floating, is proprioception.
Wiki says:
proprioception pro·pri·o·cep·tion (prō'prē-ō-sěp'shən) 
n. 
The unconscious perception of movement and spatial orientation arising from stimuli within the body itself.

Proprioception is deteriorated with drugs and alcohol. That is why traffic cops have you close your eyes and try to touch your nose with your fingers. 
By having the stump distal end floating, I loose track of, and have no feedback of, where the prosthetic leg is. I must walk slow, and watch where the leg is to know if it is in front and ready to have weight put on it.

I spent 4 hours at the prosthetic place today. We were determined to improve proprioception, comfort, and control. 
This socket needs me to wear a silicone liner against the stump skin. The socket is made of fiberglass and carbon fiber. Inside the socket is a thick plastic liner. It has the feeling of a small tire. It is flexible, but tough.

Here is me bending the inside liner of the socket with my thumb.

The inside liner is riveted to the fiberglass shell. The vacuum is formed between the flexible socket liner, and the silicone liner on my stump. That is what keeps the prosthetic leg from falling off when I take a step. So there is the stump, silicone liner, flexible liner, then fiberglass shell.

What we have been doing the last few days was putting pieces of thin foam between the flexible liner and the fiberglass shell. These foam pieces are used to push against the stump closer to the distal end, to increase proprioception. This works, BUT, the pieces of foam also increase the force needed to push the stump into the socket. The more foam, the more proprioception, but more pain. :-(

Today we cut big holes in the fiberglass shell, and put thick foam on the pieces cut out.
At first we had a ratchet assembly that pulled a stainless steel cable. This broke before we could get enough force.
Then we used my big hose clamps to pull the cut out pieces in tight once the stump is inside the socket. So the stump fits in the socket easy, THEN we add the force near the distal end to aid in proprioception and control. These movable pads put force on the femur, without putting force on the distal end.

When tight, there is a LOT of force on the stump sides. This steadies the femur and really gives me good control and it makes the whole prosthetic feel so much more like a part of my body.

The next thing we need to work on is the force required. When I release the clamps, I feel the blood rush into the stump.

But there is NO pain. I can go shopping and get in and out of the car easily.I wore the leg about 6 hours today.
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I passed the learners test part of getting a South African drivers licence. Next is to get the car registered into my name from Maddie's name. She mailed me all the required documents express, registered mail, about 10 days ago. The post office advised me today that I can go collect the documents at the post office. 10 days for express mail to go 1300 km (600 miles).

To get the car in my name needs a roadworthy inspection. The tires won't pass because they are non standard. New tires are R3000. The one brake is leaking, and that is R1000. This money is coming out of the money set aside for plane tickets to go to America. Between this and the driving lessons, I have used half the ticket money. I am now way short of money. But being short of money, is nominal now days.

I decided I'll take the drivers licence road test, in my car. It is much easier to get in and out of than the driving schools cars. I have also removed the rest place for the left foot, to give my prosthetic leg more room. But first I need the car in my name.
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Today at the pharmacy I chatted about an hour with a guy that works there. He is a right leg, above the knee amputee. It is so nice to hear someone complain exactly about the things, that I complain about. :-)

He has been using one of the very first bionic knees for about 10 years. An OttoBock C-Leg. He got a loaner unit for 2 weeks of an Ossur Rheo-3 knee with a bionic foot.
He said after a few days he was walking up and down stairs, and up and down steep slopes without a thought. He said for 20 years he has had to concentrate on walking, but with the Rheo bionic foot/knee combination he occasionally, actually forgot about the prosthetic leg.
He has had many falls in his 20 years of amputation. He has been hospitalized 3 times from falls. Usually when accidentally stepping backwards, and putting weight on the toe that breaks the leg loose, and it suddenly collapses. His wife has been with him all three times.
While wearing the loaner Rheo knee/foot combination they went to a party, and were standing talking to a guy, that was opening a beer. The beer squirted foam all over. He and his wife both jumped back. Then she screamed and reached for him, knowing he would fall. But the computer cut in and locked the knee, and he didn't even stumble. She looked at him and said "We are buying that leg."
That leg costs R850,000 ( $70,000). They are selling one of their rental houses to buy the leg. He is very excited.
He had to give the Rheo back after 2 weeks. He says his old bionic leg feels like an dangerous antique.
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Sep 05-09 2016 - Pipe legs and Driving

Sept 05 2016
I have been trying to find a way of standing to do dishes, that does not entail balancing on one leg. I came up with a piece of PVC piping that my stump fits into, and I flared the top. You can laugh, :-) but I can stand for hours now.

I also have been working on designing a socket that allows for stump volume variations. By being able to vary the volume, I can keep it tight all the time. I built this.

Again, you can laugh, BUT,... it does not hurt. No Pain. Next is to get both together, and then make a way for the pipe not to fall off when I take a step.

Online I found a socket that looks like it would work, but they want house prices for these things.

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Sep 06 2016
I went to the prosthetic place today. I told Bradley (my prosthesist) That I want a pain free walking leg by the end of the month. We discussed many, many options.
He made another cast to make another socket. It should be ready by Friday.
We plan on making this socket like a normal solid socket, but without an end on it, so the bottom is open, and also put a slit down the side, and use clamps to tighten it on tight.
I think the best clamps/straps will be similar to ski boot bindings.

My stump pain seems to be increasing, not decreasing. I think the stump is shrinking in length, which put all the muscles, scars, and skin at the end more forceful against the bone end.
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Sep 08 2016
I spent a few hours with the surgeon today. He thinks we might somehow "pull" the stump end to stretch the muscles and skin to relieve some of the force on the end of the bone.
We need to think on that.

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Sep 09 2016
I'm just back from a few hours with Bradley, the prosthesist. We tried on the new socket. It is similar to the old , hard sockets, but is split down the side to allow adjusting it's volume.
He left the bottom end closed, but wide enough that the stump never touches the bottom part. That way we can still apply a vacuum to the bottom of the stump if needed.
The socket was very tight at the top, and floppy at the bottom. Just like it should be. It caused no pain. He had made this one out of very transparent plastic, to allow seeing where it is tight and where loose by noting skin color.
Hopefully I'll walk away on the new socket next Wednesday.

This whole cancer/amputation thing has resulted in me staying away from Texas for so long that my Texas drivers licence is expiring. It will be cheaper for me to get a South African license, than to travel to the states to get a new Texas one.
I now get to experience the South African bureaucracy first hand. 100% bureaucratic bullshit. It should take a month or two. depending on how many times I flunk the driving test. Without bribing, it usually take a few flunks. Flunks pump up the stats for the inspectors to prove how hard they work, and how many tests they have to do each month.
I just chatted with a lady that flunked her driving test 7 times. Seven is a lot even for South Africa. Three seems to be about average.
I have to first get a learners permit, then I can apply to take the driving test.
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I just had coffee with a friend at a local restaurant. It was nice to get out and interact a bit.

I have been looking at the paralympics. I look at all the people competing, and find someone worse off than me. Then I look more, and find someone worse off than that person.  Then look some more, and find someone even worse off than that person. It seems there is always someone worse off than someone else. Which I guess really means that I am MUCH better off than so many others.

I read some good observations regarding the Paralympics:

 We could see blind runners taking a course unaided thanks to headsets which can watch for hurdles as well as providing left and right instructions.
(The step from driverless cars, to blind people walking, is not a large step.)

Actually our wheel chairs are like Formula One cars; they're the absolute cutting edge of technology. Thanks to carbon-fibre chairs and precise engineering, the wheel chair weight is down to just 2kg. 
(Mine weighs 18kg.)

The Paralympics is wedded to science and technology. In the paralympics charter, science is a huge part of it. It’s all about enhancement, it’s all about making people better. 
(Able bodied people will soon need body enhancements, or get left behind by disabled people.)

The ‘Brain Sled’ was designed by engineering students at Imperial college, and uses electrical signals in the brain to ‘steer’ a sled in a bobsleigh event. Now we can have totally paralyzed people competing in sports. 
(Is this still an "athletic" competition?)

The current exoskeleton can only walk slowly, and the expensive, computer-controlled hydraulic machines is used to deliver the health benefits of walking to paralysed patients. 
(Isn't an exoskeleton just a step up from a fancy prosthetic knee?)

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