Project Overview

Problem Overview

There are over 250,000 people in the United States with a spinal cord injury. Forty-seven percent of people with spinal cord injuries are quadriplegics. Quadriplegic have a loss of function or limited function of all muscles below the neck. About 5,000 people in the United States alone become quadriplegics each year[1]. Quadriplegics are restricted from performing everyday activities that are taken for granted by many people, such as listening to music. Listening to music is a leisurely activity that enhances the quality of life for many people. It is very difficult to change the song, pause, play, and alter the volume without the use of hands. Not being able to adjust the volume or change the song detracts from the listening experience. Control over a music player would be useful for the disabled, such as quadriplegics, and would make parts of life more enjoyable.
Controlling electronic devices without the use of hands could also be used by general consumers who wish to control music without hands for ease of use. This can tap into a new market of hands-free controlled devices. Eventually, controlling electronics bioelectrically can be used for a large variety of electronics and can be used daily by the general public for convenience.

Pre-Existing Solutions

While there is no existing work on a biologically controlled music player, there is related research on muscular contractions controlling other physical objects. Voluntary blinks have been used to interface with computers, but typically, the eyes are used to control devices using EOG, or electrooculography.  EOG uses electrodes to measure the electric potential generated by eye motion. It has been implemented to control physical devices such as wheelchairs[2]. More related to EMG controlled music players, electrooculography has also been used to interface with computers, control computer functions, and direct a computer cursor [3-5]. This project will interface with a computer using the electric signals produced by contractions of the extra-ocular muscles, rather than eye movement. In this way it more closely resembles EMG signal control, such as that used to control a prosthetic arm, than EOG device control [6].

Figure 1: EOG controlled computer program [7]

Design Goal

The goal of the project is to control a music player using bioelectric signals caused by muscle contractions. There are many people that are disables, such as quadriplegics, that are unable to enjoy everyday activities. There is currently technology that allows the disabled to control physical devices, such as computer cursers and wheelchairs. However, the problem being able to control a music player without the use of hands has not been addressed. This project will address this problem and create a way for the disabled to comfortably listen to the music of their choice.
The human body is a system made up of subsystems that are controlled by bioelectric signals. Bioelectric signals are a result biological events such as contracting a muscle. An electromyograph (EMG) detects the electrical activity in skeletal muscles using electrodes placed on the surface of the skin. As a skeletal muscle contracts, bioelectric signals are given off. The surface electrodes can detect the voltage changes when a muscle contracts and these changes can then be transferred to a computer using a data-aquisition system and a computer program such as MATLAB.

This form of bioelectrical signal detection can be used to control various devices such as a music player using muscular contractions, surface electrodes,  an amplifier, a data-aquisition system, and a MATLAB algorithm. This could be done by placing electrodes on the face, near the eyes. The placement of surface electrodes on the face will allow the bioelectric signals from muscle contractions of forceful blinks to be detected. The electrodes will be connected to an amplifier so the signal of the voltage change during the muscle contractions can be read more clearly. The amplifier will then be connected to an data-acquisition system so the signals can be interpreted by MATLAB. An algorithm will be written in MATLAB to interpret the data from the signals and control the music player. The different muscle contractions by the skeletal eye muscles will be able to play, pause, skip, and change the volume of the music playing through the music player.

Figure 2: Diagram of how major components of the system are connected

Design Constraints

The final product has to be easily controllable using skeletal muscle contractions. The muscle contractions need to be of a specific strength that is not too soft that it goes undetected, but not so strong that it is uncomfortable for the person to perform. The placement of electrodes should be unobtrusive and there cannot be an excessive amount of electrodes on the face. The placement of electrodes should not interfere with basic activities such as talking. The design also has to be cost effective, otherwise it will not be profitable. The design and algorithm also needs to be reliable and work about ninety percent of the time, otherwise it will not be practical to use.

Project Deliverables

The electrodes and MATLAB algorithm will be able to successfully measure biological signals caused caused by the voltage changes during facial muscle movement. The MATLAB algorithm will be able to interpret these bioelectric signals from the electrodes and then execute a set of commands to control a music player. This will allow a person to control a music player using their facial muscles.

Project Evaluation

A series of preliminary tests using multiple subjects will be conducted in order to determine the quality of the project. These preliminary tests will measure how well the music player can execute the basic functions of play, pause, skip, and volume control with multiple people. In order to be considered successful, at least a ninety percent reliability must be achieved.

Project Schedule

Weekly Schedule for the Blog, Mechanical Components, and Algorithm

Projected Budget

The disposable electrodes cost about $0.30 cents each. Many will probably be used during testing and refining our project. We estimate that approximately $10.00 will be spent on electrodes. An amplifier, such as the Ti-INA129PA, costs between $5.00-$10.00. A data-aquisition system to connect the signals from the electrodes to MATLAB will cost around $30.00. The total estimated cost for the entire project would be $50.00. However, all of the material will be provided by Drexel, so there are no projected costs right now.

Figure 3: Data acquisition (DAQ) [8]