Print PDF
Favorite
Email
Step 4BEND SENSORS
All three Puppeteer suits to date are based on the principle that pressure sensors also react to bend. This is true since pressure is exerted thorough the fact that materials pressure against each other when bent because the outer layer must stretch and presses against the inner layer, which has excess material that needs to go somewhere.
Shortly prior to the first Puppeteer project we had developed the technique of making pressure sensors sandwiched between two layers of neoprene. The reason we chose to use neoprene was because we had been using it to make fabric buttons for another project http://www.massage-me.at Neoprene has some nice qualities for making pressure sensors since it creates a natural force feedback as well as spreading the pressure evenly.
Fabric Bend Sensor
The first fabric bend sensors we fabricated from two layers of 1.5mm neoprene, which has polyester jersey adhered to each side. The fact that fabric was mounted on either side of the actually neoprene made it possible to fuse a piece of conductive fabric to either piece of neoprene using iron-on interfacing, a heat glue common in quilting and sewing. In between the two pieces of conductive fabric we sandwiched a piece of Velostat, which is basically the black plastic that sensitive electronic components or circuits are packaged in to protect them from electrical charges or statically charging themselves. Velostat is carbon-impregnated polyolefin and is a bad conductor but also has the quality to reduce its resistance under pressure.
All these layers are kept in place by lightly stitching around the edges of the neoprene.
In the first Puppeteer suit we had twelve such sensors places around the body. Although the sensors are stable, they do such a lot of power, even when they are not being bent, since there is enough initial pressure on the sensor so that there is a constant flow of electricity that increases even more when bent.
Conductive Thread Bend Sensor
There is an Instructable that covers this Bend sensor >> http://www.instructables.com/id/Fabric_bend_sensor/
One change that was made in the next Puppeteer suit was to reduce the conductive surfaces on either side of the Velostat. So instead of fusing conductive fabric, we stitches a few diagonal stitches using conductive thread on either side of the neoprene. This reduced the initial conductivity a lot so that some of the sensors that were not mounted to tightly against the body, made no electrical connection unless pressured/bent.
Also, circuit wise instead of power all sensors and measuring the changes in power passing through them we used a multiplexer to individually power and measure each sensor individually in super fast succession, so seemingly seamlessly, all at once. This, along with the conductive thread alternative lowered the energy consumption to a good level.
I am also selling these handmade fabric bend sensors via Etsy. Although it is much cheaper to make your own, purchasing one will help me support my prototyping and development costs >>
http://www.etsy.com/shop.php?user_id=5178109
Shortly prior to the first Puppeteer project we had developed the technique of making pressure sensors sandwiched between two layers of neoprene. The reason we chose to use neoprene was because we had been using it to make fabric buttons for another project http://www.massage-me.at Neoprene has some nice qualities for making pressure sensors since it creates a natural force feedback as well as spreading the pressure evenly.
Fabric Bend Sensor
The first fabric bend sensors we fabricated from two layers of 1.5mm neoprene, which has polyester jersey adhered to each side. The fact that fabric was mounted on either side of the actually neoprene made it possible to fuse a piece of conductive fabric to either piece of neoprene using iron-on interfacing, a heat glue common in quilting and sewing. In between the two pieces of conductive fabric we sandwiched a piece of Velostat, which is basically the black plastic that sensitive electronic components or circuits are packaged in to protect them from electrical charges or statically charging themselves. Velostat is carbon-impregnated polyolefin and is a bad conductor but also has the quality to reduce its resistance under pressure.
All these layers are kept in place by lightly stitching around the edges of the neoprene.
In the first Puppeteer suit we had twelve such sensors places around the body. Although the sensors are stable, they do such a lot of power, even when they are not being bent, since there is enough initial pressure on the sensor so that there is a constant flow of electricity that increases even more when bent.
Conductive Thread Bend Sensor
There is an Instructable that covers this Bend sensor >> http://www.instructables.com/id/Fabric_bend_sensor/
One change that was made in the next Puppeteer suit was to reduce the conductive surfaces on either side of the Velostat. So instead of fusing conductive fabric, we stitches a few diagonal stitches using conductive thread on either side of the neoprene. This reduced the initial conductivity a lot so that some of the sensors that were not mounted to tightly against the body, made no electrical connection unless pressured/bent.
Also, circuit wise instead of power all sensors and measuring the changes in power passing through them we used a multiplexer to individually power and measure each sensor individually in super fast succession, so seemingly seamlessly, all at once. This, along with the conductive thread alternative lowered the energy consumption to a good level.
I am also selling these handmade fabric bend sensors via Etsy. Although it is much cheaper to make your own, purchasing one will help me support my prototyping and development costs >>
http://www.etsy.com/shop.php?user_id=5178109
| « Previous Step | Download PDFView All Steps | Next Step » |
 |
Add Comment
|
