Problem Overview
Many individuals have trouble with mobility as a result of the way traditional wheelchairs are made. These wheelchairs often require a minimal turning radius in order for someone to turn. This can often limit an individuals ability to turn in tight spaces and therefore, makes things more complicated for the individual. Another problem individuals who are wheelchair bound encounter is that they are not able to reach objects on higher counters or shelves. This further constricts how much the individual can accomplish from their wheelchair.
Design Constraints
There are numerous constraints that make this project more complex. These constraints are in place because of the limited amount of time, budget, and the amount of the materials being used. One of the most overarching constraints for this project is that the group only has eight weeks to come up with an idea, engineer a design to meet the goals of the project, and to test the design. One of the the other constraints to this design is that the chair the user will be sitting in while controlling the motors is made out of plastic, therefore the motors cannot exert a force that is greater than what the chair’s materials can withstand. If this chair breaks the user may be injured from the motor and the entire structural integrity of the design will collapse.
Another constraint to this project is that the motors must be powerful enough to lift the weight of the chair and the user together. This ties into cost because the stronger the motor the more expensive. Some of the aspects of the project that are necessary are the engineering solutions that will have to be developed in order to build the chair assembly, and to integrate the computer signals to electrical signals that will control the motors. One of the smaller constraints that was expected since the beginning of the term was that the group will have to learn how to use MATLAB to interpret the signals received from the sensors and then translate those signals by using a code created in MATLAB. Another constraint is the access to the machine shop and available time to work on this project. In addition, the time that it takes for the components of this project to be purchased and shipped to the school delays the amount of time allotted for testing.
Another constraint to this project is that the motors must be powerful enough to lift the weight of the chair and the user together. This ties into cost because the stronger the motor the more expensive. Some of the aspects of the project that are necessary are the engineering solutions that will have to be developed in order to build the chair assembly, and to integrate the computer signals to electrical signals that will control the motors. One of the smaller constraints that was expected since the beginning of the term was that the group will have to learn how to use MATLAB to interpret the signals received from the sensors and then translate those signals by using a code created in MATLAB. Another constraint is the access to the machine shop and available time to work on this project. In addition, the time that it takes for the components of this project to be purchased and shipped to the school delays the amount of time allotted for testing.
Existing Solutions/Related Work
Researchers have been attempting to bioelectrically control wheelchairs through a variety of different methods in recent years. For instance, researchers from the United Kingdom and China collaborated to create a wheelchair controlled by the forehead, eye, and jaw. To identify the facial movements, the researchers used both an EMG and an EOG. There were three parts to the experiment which included a device called Cyberlink composed of a data processing box and a wearable headband, an intelligent wheelchair platform in order to simulate “real-world performance,” and a human machine interface, which classified selected movements (Hue & Wei, 2009). Three electrophysiology sensors are attached to the forehead in order to detect muscle movement. The signals are then transmitted to amplitude amplifers and encoded into EMG and EOG data. The researchers used four signals to control the chair, and they are forehead single click trigger, forehead double click trigger, left eye closing trigger, and right eye closing trigger (Hue & Wei, 2009). By using these signals, the wheelchair user can control their chair while still observing their environment. Researchers desire to use EEG signals to control wheelchairs in the future; however, as of now EMG and EOG has a faster response speed than EEG.
Not only are forehead and eye muscles used, but researchers have developed methods for bioelectrically controlling chairs with tongue movements. The movements were detected with a bar magnet mouthpiece in the oral cavity that connects to the tongue. Additionally, there is a “hollow cylindrical central,” which support the bar magnet, and the signals are processed in parallel transmission channels (Buchhold, 1995). Four tongue movements—north, south, east, and west—were transmitted through the mouth piece, amplified, and converted into digital signals. This method is useful because the user can observe his or her surrounding without the transmitter confusing these observations with signals to move the chair.
Although EMG and EOG methods are effective, researchers ultimately want to create a wheelchair that is solely controlled with EEG. In 2005, Tanaka, Matsunaga, and Wang attempted to control the direction of a wheelchair using EEG. The design included an electrocap with electrodes, electroencephalography (EEG) amplifier, an electrode box, a digital converter, and a computer (Tanaka et al. 2005). To further the complexity of the experiment, the researchers attempted to use the jaw and eye muscles to control the speed of the chair. Signals were transmitted from the EEG, and converted using the digital converter. The signals were read using a brain-computer interface, which analyzes neural signals and acts as a communication channel between the brain and the computer (Tanaka et al. 2005). Although the results were encouraging, each subject would need to concentrate and practice in order to fully control the chair with these signals. For this reason, bioelectrically controlled wheel chairs, whether through eyes, muscles, or brain signals, continue to be a popular and useful topic worth researching.
Design Goal
The goal of this project is to engineer a better device for those that are wheelchair bound. There have been many different developments of the wheelchair for different type of patients, but our group wants to design something different. We plan on constructing a wheelchair that rotates the chair depending on neck movement. If the patient turns his or her neck left, the chair will rotate left, and visa-versa.
By connecting probes to the different target muscles of the neck to an electromyogram, data can be gathered to discover what the readings look like when the neck is turned right and left. These readings will be interpreted by MATLAB and then the chair will move accordingly.
Instead of just rotating the chair, our group is also going to incorporate a piston in the base of the chair in order enable the patient to move the chair up and down. This will make the act of reaching items from counters and heights out of the range of a normal chair a lot easier. This will be done by using the same methods as rotating the chair left and right, but instead of the left and right motion of the neck, the upwards and downwards motions will be taken in account.
By connecting probes to the different target muscles of the neck to an electromyogram, data can be gathered to discover what the readings look like when the neck is turned right and left. These readings will be interpreted by MATLAB and then the chair will move accordingly.
Instead of just rotating the chair, our group is also going to incorporate a piston in the base of the chair in order enable the patient to move the chair up and down. This will make the act of reaching items from counters and heights out of the range of a normal chair a lot easier. This will be done by using the same methods as rotating the chair left and right, but instead of the left and right motion of the neck, the upwards and downwards motions will be taken in account.
Project Deliverables
- Successfully receive signals from EMG sensors
- Successfully interpret signals from EMG sensors
- Convert signals from EMG sensors to electrical signals using MATLAB
- Design a chair prototype to be able to test the design
- Integrate signals from MATLAB and hydraulic lift to raise and lower chair
- Integrate signals from MATLAB and rotation system to successfully rotate chair
- Build entire project
- Test final design
Project Schedule
Week One
In Lab: Group was formed and design project topics were discussed.
Week Two
Outside of Lab: Group met to further discuss topics. The website was made and the requirements that were to be done were finished and sent to the instructor.
In Lab: Finalize the design topic and begin to divide up the work for each group member.
Week Three
Outside of Lab: Gather the necessary research put the design proposal together.
In Lab: Gathering and interpreting data, using MatLab, that will be used to rise, lower, and spin the chair by using the muscle movements from the neck.
Week Four
Outside of Lab: Order and purchase all of the parts necessary for the project. Begin assembling the motors that will be used on the chair.
In Lab: Continue working on the algorithm in MatLab.
Week 5-9
Outside of Lab: Continue working of the mechanical aspects of the project and begin to test the finished product. Make modifications that are necessary.
In Lab: Continue to working on design and make the necessary modifications.
Week 10
Outside of Lab: Make last adjustments to final product, type the final design report, and put together the presentation of our work.
In Lab: Give presentation on our accomplishments and our design. Give a demonstration of our final product.
In Lab: Continue working on the algorithm in MatLab.
Week 5-9
Outside of Lab: Continue working of the mechanical aspects of the project and begin to test the finished product. Make modifications that are necessary.
In Lab: Continue to working on design and make the necessary modifications.
Week 10
Outside of Lab: Make last adjustments to final product, type the final design report, and put together the presentation of our work.
In Lab: Give presentation on our accomplishments and our design. Give a demonstration of our final product.
Project Budget
Materials
Chair- $50
Motors
Hydraulic Lift- $130 http://www.firgelliauto.com/product_info.php?cPath=93&products_id=106
Rotating Motor- $15 http://www.midwestmotion.com/products/rightangled/12VOLT/1019RPM.htm
Sensors (Electrodes)- $12 http://www.tenspros.com/15-x-15-Ultra-Premium-Square-Tan-Cloth-Electrode-TYCO-Gel-_p_194.html
Misalleneous Items- $50
Total Estimated Price: $257
References
N. Buchhold, “Apparatus for Controlling Peripheral Devices Through Tongue Movement, and Method of Processing Control Signals,” United States Patent and Trademark Office, Vol. 43, No. 12, pp. 19-29, Oct. 1995.
H. Hu & L. Wei, “Use of Forehead Biosignals for Controlling an Intelligent Wheelchair,” IEEE International Conference on Robotics and Biomimetics, Vol. 28, No. 4, pp. 110-113, Feb. 2009.
K. Tanaka et al., “Electroencephalogram-Based Control of an Electric Wheelchair,” IEEE Transactions on Robotics, Vol. 21, No. 4, pp. 762-766, Aug. 2005.
No comments:
Post a Comment