"Workout Buddy"

a muscle fiber stimulation sensor and datalogger

Initial Project and Group Identification Document

January 29, 2009

Senior Design - Dr. Richie

University of CentralFlorida

Department of Electrical Engineering

Josh Hamby

Andrew Lee

Scott Martin

Matthew

Workout Buddy

a muscle fiber stimulation sensor and datalogger

Group Members:

Andrew Lee

Josh Hamby

Matthew McNealy

Scott Martin

Sponsor:

Veteran Affairswill cover 100% of the project.

Narrative Description:

The goal of this project is to build an intelligent handheld Electromyograph for use by amateur bodybuilders.

In the gym when one is attempting to gain strength, size and weight, it is useful to track one's progress. Amateur weightlifters get the most benefit when they keep track of their exercises, the weights lifted, their # of repetitions and sets on a regular basis. When progress is tracked, additional motivation is gained and areas for improvement are more easily assessed. Our unit will automatically track all of this over time, as well as rate the intensity of each rep, set, and workout session against previous efforts.

An electromyograph detects the electrical potential generated by muscle cells when these cells contract, and also when the cells are at rest. Using a sensor network attached to the body, we will record, store, and interpret the data, and then output this information to user via a display.

This project will allow the group to explore and develop our skills in our various interests in Biomedical Engineering, Embedded Systems, Electronics, and Wireless Protocols.

Specifications and Requirements:

-Must produce a usable signal from sensor within range from datasheet 20-200Hz, 1-3 V

-Must automatically count Reps and Sets and Calculate Intensity

-Must store data over time indefinately in flash memory

-Must provide usable metrics to user (average, last, current intensity per exercise, rep, and workout)

-Must remain powered for duration of long workouts (approx 2 hrs)

-Must have a User Friendly Interface

-Must work in local areas where temperature fluctuates between 40 and 100 degrees F.

-Must weigh less than 1 lb.

-Must have dimensions no larger than 2" x 5" x 7"

Block Diagrams:

______

Block Descriptions:

INSTRUMENTATION BLOCK

  • Electrode: The skin surface sensor is an electrode placed over the muscle. The sensor is used to measure anddetect the electrical potential generated by muscle cells when these cells contract.Measured EMG potentials range between less than 50 μV and up to 20 to 30 mV The sensor transmits this data to the amplifier.
  • Amplifier (opamp): The signal is amplified by a gain factor of 100 to 1000 to produce an amplitude of approximately 3V.
  • Rectifier: A full-wave rectifier converts the whole of the input waveform to one of constant positive polarity.
  • Filter: The usable signal is expected within the 20 -200 Hz range so set cutoff for low pass filter above that. Literature indicates a notch may also be necessary to remove 60Hz signal as the human body can act as an antenna for surrounding EM waves.
  • Integrator: This block gets the area under the curve and is used to measure electrical work done.This step may be performed in software.

MICROCONTROLLER BOARD BLOCK

  • ADC: The ADC will take in the analog filtered signal and convert it to a digital signal. The Atmel Atmega 168 has a 6-channel 10-bit ADC in PDIP Package. If necessary can consider offloading to separate IC.
  • Memory: The signal must be storable over time. The Atmel Atmega 168 provides16K Bytes of In System Self-programmable Flash program memory. Should this not be enough, we must interface an additional flash memory IC.
  • Code: The code will run on a microcontroller, which will interface electronically with all parts of the system. It will perform. Candidates include Atmel Atmega 168, TI MSP430, and PIC18F452. An MCU with a free C compiler/development tools is preferred.
  • USB: The device will connect to any USB capable computer and output CSV (comma separated value) files for analysis in a user defined program (ie Excel)
  • Power Circuit: The unit must be powerable from Batteries at approx 5V for the operation of the MCU (1.8-5.5V) LCD (2.7-5.5V). Rechargable Li or NiMH are better than Alkaline.

USER INTERFACE BLOCK

  • Display: A friendly UI will be provided. Best current candidate for the display unit is a 2 x 20 monochromatic LCD with standard Hitachi controller HD44780. Other candidates include the color Nokia 128x128 LCD-00569.
  • Buttons/Rotary Encoder: The User will have a method interact tactically with the unit - to select from pre-programmed exercises, to enter various data, to toggle between various displays.
  • CSV FILE: A file format used to describe tabular data. One line corresponds to one row; commas correspond to columns. A sample Excel sheet to display and visualize data from the unit will provided.
  • Fabric Strap: Used to attach to the various muscle groups to be measures. Neoprene and velcro, with embedded electrodes.

Cost

(LABOR)

$40/hour x 150 hours to complete 2.5 (overtime)

(12 weeks with 12.5 hours per week) = $6000/person

Total Labor = $15000 X 4 People = $60,000

ITEM / # / COST / METHOD TO ACQUIRE
Electrodes / 10 / $10.00
Opamp Ic Amplifier / 1 / $2.00
Opamp Ic Filter / 1 / $2.00
Opamp Ic Integrator / 1 / $2.00
Velcro/Fabric / $5.00
Wire / $5.00
Atmel 168 8bit MCU / 1 / $7.00
MCU programmer / 1 / $30.00
LCD screen / 1 / $5.00
Buttons / 2 / $1.00
Rotary Encoder / 1 / $3.00
USB controller IC / 1 / $4.00
USB connector / 1 / $2.00
Battery / 1 / $10.00
PCB prototyping / 1 / $60.00
Various resistors and capacitors / $15.00
TOTAL COST

Project Milestone

See Attached

Decision Matrix

Ideas to incorporate given enough time, money and motivation:

-wireless data transfer between unit and PC (bluetooth, IR, RF)

-Additional sensors: Heart monitor, EEG