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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