SparkFun Forums

[lucidgold]

Hello everyone,

This is my first post here. I am trying to build a glove with 5 flex sensors and one vibrotactile transducer, but would like this to be completely wireless using Bluetooth.

What board would have bluetooth and enable me to put 5 sensors as input and the transduder as output?

[riden]

Basically, you need five analog to digital channels and an output port that will be used to drive your transducer. As far as I know, the only board with an integrated bluetooth module carried by Sparkfun is the Arduino bluetooth at $150. You might want to look at a combination of a bluetooth module ($60) and something like a bit-whacker ($25). You may also be able to find a suitable combination from other vendors.

Bluetooth: http://www.sparkfun.com/commerce/produc ... ts_id=8461

Processor card: http://www.sparkfun.com/commerce/produc ... cts_id=762

[silic0re]

Sounds neat! What sort of bend sensors are you thinking of using?

I wonder if hacking an old Power Glove to interface a microcontroller with its bend sensors would help? (But, if I remember correctly, these were sensors that changed their capacitance the more they were bent -- that might not be so easy to interface directly to a microcontroller).

[certron]

What is most cool about the Nintendo/Mattel Power Glove system was how it actually sent the data. The two ultrasonic transducers were used to send a 12-bit signal to the 3-receiver sensor bracket, from which the flex of the fingers (2 bits for 4 positions of 4 fingers) and possibly the buttons were decoded and sent to the console. This was the digital part of the signal. The same signal was also used in an analog fashion to determine the glove's position in 3-D space. At least, I think that was the way it worked.

The sensors were piezoresistive metal strips, and the pinky finger sensor was 'engineered out' to save costs and complexity.

[Philba]

depending on the capacitance range, it's really pretty easy to interface to a microcontroller. Basically, you time the RC constant. There are several ways to do it:
- use an ADC pin. Vcc to R to C to gnd. R/C junction to the pin. set it to digital out, output a zero to discharge the cap, switch to Analog and time how long it takes to get to some predetermined value. Pick the value of R so the rise is easy to measure.
- use a comparator like above but you will probably need a second pin to discharge the cap.

[riden]

Some of the flexible sensors are actually variable resistors which makes the job even easier. I saw them listed in the Jameco catalog and Kronos Robotics has a write up on using them. http://www.kronosrobotics.com/an135/DAN135.shtml

BTW, a year or two ago, a young man won a rather substantial scholarship by building something very similar. He used the hand as a communication device. It would read the movements of the hand, transmitting the gesture data to a controller in the pocket. I think it was some type of sign language to speech converter. It was a very creative and interesting project.

[lucidgold]

Very nice.. thanks!

So the cheapest way to go is buy USB Bit Wacker - 18F2455 Development Board, and attach the Bluetooth DIP Module? I mean, is it not worth spending $150 on the Arduino bluetooth? Which would be the easiest way for me?

I am trying to build a wireless glove, using the same flex sensors on this page (btw thanks for posting it): http://www.kronosrobotics.com/an135/DAN135.shtml

I want to try and grab objects, once the object is grabbed I will send a tune to the transducer to tell the user that he is currently holding on to the object. But to do that I need to know finger positions..

[riden]

I have to admit that even though I have a USB Arduino board, I tend toward PIC based solutions. But I took a closer look at the Bluetooth Arduino and I think it would make a good choice as well. It is 1) small, 2) has a DC to-DC converter so it can be powered with as little as 1.2v, 3) you can program the device via the Bluetooth interface -- sweet, and 4) it has a bigger processor than my USB board. All of these features would work well in your application. You can go the Arduino site and download the free development tool and see how you like it.

Besides programming the device, how does the Bluetooth interface figure in? Are you thinking of having the glove capture the data, send it to PC, and have the PC identify the object, and send back a signal to the board? That sounds like a good way to go during development.

Perhaps others can weigh in on the Arduino boards.

[edit]I forgot to mention that I happened upon this page which might be useful: http://www.tufts.edu/programs/mma/emid/ ... riete.html

[lucidgold]

Yes! I would like for the glove to capture the data and send it to the PC, and of course the PC must identify the object and send back a signal to the board which then will turn on the transducer if I wanted.

How about the Wiring Programming Platform: http://www.sparkfun.com/commerce/produc ... cts_id=744

And then attach a Bluetooth Modem - BlueSMiRF: http://www.sparkfun.com/commerce/produc ... cts_id=582

Is that a better choice? Its gona cost me about $150 as well.. or is the Bluetooth Arduino still better?

[lucidgold]

I went ahead and purchased the USB Arduino board, just because its cheap and once I have a good design I will get the bluetooth board and make it fancy.

I also purchased 3 flex sensors from Jamaco.. about $12 each. I am still waiting on EAI, I emailed them regarding their C-2 tactor, which is not sold anywhere.

Do you guys know of other vibrotactile transducers? Another one I found was the AEC Tactaid VBW32 which is about $90... its a lot! :S

[silic0re]

Hi there,

I'm not sure what you mean by a 'vibrotactile transducer', but you might be thinking of something similar to a vibrating pager motor?

Sparkfun has tiny versions of these:
http://www.sparkfun.com/commerce/produc ... ts_id=8449

(but appear to be out of stock -- if you don't mind a slightly larger version, you could use the ones BG micro has: http://www.bgmicro.com/index.asp?PageAc ... odID=10135 ).


silic0re