EMG controller project


I am working on a senior project and my group and I are using the arduino uno board to make a myoelectric controller. Here is a little bit of background: the controller will input an analog EMG signal from Delsys double differential EMG electrodes (and through EMG system with bandpass of 20-450 Hz for environmental noise) to the controller through a BNC connector. It will then filter the EMG signal (High pass, rectify, low pass) to create a control signal. This control signal will then be subject to 2 potentiometers adjusting the gain of the signal, and the threshold of the signal. This signal will then need to be converted back to analog and outputted (0 to 10V) through BNC connectors to proportional pressure controllers (PPC's). The threshold is adjustable to control when the PPC's turn on (with what level of muscle activation), and the gain is adjustable to control how strong the control signal is. (Also, this will be done for two sides of the body, so all the above X2).

I guess a few discrete questions I have are: 1) Which is the best way to filter the EMG signal (high and low pass)? We were planning on digitally filtering. 2) For the digital--> analog conversion at the end, is it advisable to buy a DAC piece? What is the benefit to this? 3) We will obviously need BNC connectors, I'm looking into getting these, anyone with experience? http://www.gravitech.us/bnc50ohmbrbo.html

We are biomedical engineers with just about no experience in the electrical engineering area, and so any help would be GREATLY appreciated! That being said, I am trying to teach myself -- I have done basic tutorials with the arduino board (LED's, blinking, dimming, etc) and have spend my weekend searching and reading many of the forums:)

Thank you in advance, any information helps!

sorry i cant be of much help, but the code here(http://pulsesensor.com/) for the "pulsesensor" contains a high pass and rectify section of code. although i have no idea how it works :)

the pulsesensor is a heartbeat sensor, so that's pretty close to what your doing, right?

Thanks for your reply! That should help some, at least get us on the right track!

I have done some more research and found out the a DAC IS needed as the arduino does not output a true digital signal (only PWM). Therefore I have been looking at these two pieces:

http://www.sparkfun.com/products/9719 http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en020399

The first is on a breakoutboard, which I think would be very helpful. The only problem is I think we might need a dual channel DAC (not sure what "parallel" means). We need to output 2 signals (control signal for right side and left side). The second states it is a dual channel DAC, but is not on a breakoutboard. Am I right in my assumption that we will need a dual channel? How much easier do breakoutboards make things?

How to connect delsys DE-2.1 Single Differential Surface EMG Sensor with arduino what does the four pin in the wire of the sensor stand for? urgent Help needed.

Hi, im intrested in experiencing with EMG and my arduino mega, but I've seen different modules form EMG for arduino. What is the best, or the most recomendeded? What differences have the commercial module, for example http://www.ebay.com/itm/Free-shipping-Arduino-is-compatible-with-electromyography-EMG-acquisition-circu-/111972725022?hash=item1a1218311e:g:AHMAAOSw3mpXFJOp or http://www.ebay.com/itm/SHIELD-EKG-EMG-with-SHIELD-EKG-EMG-PA-EKG-EKG-arduino-shield-kit-including-lead-/331867333479?hash=item4d44d5a367:g:tYoAAOSw6btXSija

in comparison with https://backyardbrains.com/products/diyMuscleSpikerShield

Thanks for help!

I know next to nothing about EMG, but as far as I can find out it produces signals in the tens uf uV to tens on mV amplitude in the range 7-20 Hz......

So why are you interested in the 20 - 450 Hz range?