QUALITY OF LIFE IMPROVEMENT WITH VIBRATIONS

Jeffery L. Norrell, Ana Maria Castano, Robert Stone Department of Mechanical Engineering Dennis Chapman School of Social Work The University of Texas at Austin, Austin, Tx

ABSTRACT

Providing stimulation to students, part of the philosophy of inclusion, is a primary educational goal at Rosedale School. For students with multiple physical disabilities, vibration is one of the most effective forms of stimulation. Studies have also shown the therapeutic value of vibration. Under proper supervision vibratory stimulation produces increased interaction between the student and environment and basic quality of life improvements. To facilitate this supervised stimulation, the team designed and manufactured a device capable of delivering low amplitude vibration (2 mm) to the student while maintaining flexible and simple operation.

BACKGROUND

The faculty and personnel of Rosedale, a school for students with disabilities and a member of the Austin Independent School District (AISD), operate with several goals in mind, such as the physical and mental education of their students as well as the improvement of both work and social skills. Physical education quite often is used to improve the range of motion of a student, whereas mental education increases the cognitive ability. Work and social skills center around normalization, the inclusion of students at Rosedale into the community.

An important aspect of any teaching is the responsiveness of the students. A responsive student participates and learns much more readily than a withdrawn student. To this end, interaction between students and teachers at Rosedale makes use of many different skills, methods, and tools. The responsiveness of the student is increased by both putting a student at ease and providing them with a stimulus to which they can respond.

While many students respond to stimuli such as sound and light, there are some who only respond positively to vibration. At Rosedale, vibration is generally used with students who have profound cognitive and physical disabilities. One student in particular, ``John,'' has been observed to be extremely tactile defensive and only respond to vibration, specifically a commercial, hand-held massager . In many instances, the massager is used to calm an upset student. When the massager is set in his hand, ``John'' places it near his ear and holds it there. This has a two-fold benefit in that the vibrations calm ``John'' and holding the massager is physical therapy for his hands. Not all students can necessarily benefit from holding a massager. In some instances, a student may need vibrations for stimulus, allowing focus on another learning or therapeutic activity. However, actively holding the massager in their hand can detract from other activities.

STATEMENT OF THE PROBLEM

The goal of this project was to design and fabricate a device capable of supplying a vibrational stimulus to a student. The vibrations may be used to increase the responsiveness of the student so that teaching and therapy can ensue. Vibrations may also be used to teach cause and effect relationships. Additionally, should a student become upset, the vibrations can be used to soothe the student.

DESIGN

In the solution of any problem, especially design problems, an organized approach is extremely beneficial. A structured approach to design assists engineers in creating safe, useful products by reducing oversight, creating extensive documentation of the process, and ensuring the voice of the customer is heard throughout the design. The authors applied the methodology set forth by Ulrich and Eppinger to the design of a vibrational device [3].

The first step in the methodology is to determine what the customer wants through site visits, observation of the currently used system, and customer interviews. Using Quality Function Deployment (QFD), the design team then translates the customer needs into quantified engineering specifications [3].

The specifications are then used throughout the rest of the design process; concept design, embodiment design, and prototyping. Prototypes are the first opportunity for the design team to present the design to the customer for evaluation. Customer feedback provides insight into problems or overlooked design issues. These problem areas and oversights can be redesigned and implemented before the product goes to final production.

To facilitate embodiment design, the design team broke the overall system into components: a vibration unit, a padded holder for the vibration unit, a control box, and a power system. The vibration unit creates the actual motion resulting in the vibrational stimulus. The holder allows stimulus transmission to the student. The control box provides a means of controlling vibration intensity. The power system supplies the needed energy to the vibration unit. Having demonstrated feasibility, the team was able to proceed to construction of an alpha prototype.

It is worthwhile to discuss the safety and response of the students in terms of this design project. The two primary questions to consider are, ``How do the vibration frequency and amplitude affect the student's response?'' and ``Is there any potential damage to the vestibular system or a negative impact on the student's proprioception?'' Because students at Rosedale are often non-communicative, the student response to vibration and it's impact on proprioception is determined by observation of physical cues. This observation must be performed by people who are both qualified to do so and familiar with the student in question. This is routinely done at Rosedale, so that any detrimental effects of the vibrational device can be readily detected. At the vibration level of this device, tests have shown that physical damage to the vestibular or other physiological systems can be ruled out [2].

DEVELOPMENT

With a thorough understanding of the customer requirements and resulting design issues, the design team created an alpha prototype demonstrating the design both in terms of functionality and manufacturability. The team designed and constructed each of the individual system components discussed above. The primary component of the vibration unit is a small direct current (DC) motor with an off-centered mass mounted to the shaft. The motor/mass assembly provides a very quiet and low cost means to generate vibration. In a room with normal conversation, the motor cannot be heard. A short length of polyvinyl chloride (PVC) pipe is used as a housing for the motor/mass assembly. The padded holder, resembling a blood pressure cuff, is sewn out of dark blue denim with nylon padding inside. The vibration unit is removable which allows machine washing of the holder. The control box houses an on/off switch, connectors for power transmission, and potentiometers, or variable resistors, for speed control. Through the use of multiple connectors, five as specified by the customer, several vibration units can be connected and independently controlled. Lastly, the power system consists of two primary components. The first is an alternating to direct current (AC-DC) adapter. This allows the device to be powered using wall current. The second component of the power system is male and female RCA plugs, combined with speaker cord. These plugs and cords are commonly seen on home stereo equipment. The use of the plugs allows holder disconnection from the control box in case any of the holders are not used.

The team presented the alpha prototype to our customers at Rosedale, where it was tested on two students, ``John'', discussed above, and ``Bill''. ``Bill'' also has profound cognitive disabilities and is extremely physically involved. ``John's'' response to having a vibration device attached to his arm, as interpreted by the classroom staff, was positive and beyond that expected. Generally withdrawn due to his tactile defensiveness, ``John'' moved his arm with the vibration device attached and put the device near his ear. According to the classroom staff, this movement is rare for ``John'' and has potential physical therapy implications. ``Bill'', having the vibration device placed on his forearm, was initially pleased but quickly became upset. This reaction very quickly revealed an oversight in the design. ``Bill'' was not able to remove the device from his arm. Given the opportunity to hold the device, ``Bill'' both held it near his ear and began to mouth the device. After several moments, he dropped the device. ``Bill'' also attempted to grab the power cord to the cuff. The classroom staff expressed concern over the dependency on wall current as a power source. During trips off-campus, such as to a restaurant or worksite, a wall plug may not be readily available. Lastly, one of the staffmembers observed that, with longer cords to the vibration devices, they could be used with multiple students.

The design team used the information gained from the alpha prototype to create the beta prototype, shown in Figure 1. The beta prototype included device redesign as well as functionality addition.

First, the holder was redesigned to also allow hand holding, if desired. Now a variety of holders are offered to the customer to allow attachment around an arm or leg, or holding in a student's hand. The speaker cord was changed to black lamp cord, reducing the cord's visibility, and the length was increased to eight feet. For increased portability and convenience during off-campus trips, a battery pack, with integral speed control, was also designed and constructed. Lastly, the vibration units were sealed against liquids, increasing student safety should they mouth a holder.

DESIGN EVALUATION

Commercially available, low cost hand massagers are currently used to provide a vibrational stimulus to many of the students at Rosedale. However, use of these readily available devices comes at a cost beyond that of the price tag. During off-campus visits escorting the students from Rosedale, teachers and assistants are aware of the stares from people unaccustomed to people with disabilities. These uncomfortable stares are increased when a student uses a hand-held massager for comfort. In addition, should a student need their hands for some other work or learning activity, holding a hand massager can limit their actions. It is important to note that some students benefit from the action of holding or grasping a hand massager.

The vibrating pads, created by the design team, address all of these issues. The holders, resembling blood pressure cuffs, are extremely normalizing. Many people are familiar with blood pressure cuffs and will not give the padded holder a second look. The holders, affixed to a student's arm or leg, will not interfere with any hand-oriented tasks a student may undertakes. However, if a student's task is to actually hold the vibration device, this functionality has been maintained. The vibrations comfort the student and aid them in interactions with their environment. As with many engineering designs, the current project had common specifications such as durability, low cost, and safe use. The vibration device, however, goes beyond these issues and tackles quality of life head on.

CONCLUSIONS

The overall design statement for this project, as discussed above, is the creation of a device capable of supplying a vibrational stimulus. The vibration device satisfies the design team's mission by providing localized vibratory stimulation, allowing user control of frequency and operation at a safe vibration level.

Customer needs, such as low cost, ease of use, safe operation and durability, are all met. The social and psychological needs of the students are also evaluated. This evaluation impacts the design by emphasizing that the product not stand out in public.

The students at Rosedale who tested this device reacted positively, with only one notable exception. The one negative reaction, however, led to product improvements which are incorporated into the final prototype.

Future development of this device must address several possible areas for improvement. In particular, part count and assembly time need to be reduced. The device fabrication and assembly do not require any specialized skills, but they do involve many steps.

The bottom line is that the design of the vibration device meets all engineering requirements. More importantly, through continuous customer interaction, the vibration device evolved into a product that meets the needs of the students, faculty, and staff of Rosedale School.

ACKNOWLEDGMENTS

We wish to express our thanks and gratitude to a number of people. First, to the students, faculty and staff of Rosedale School for providing such a worthwhile and exciting project, as well as for all of their assistance throughout the project. Thanks also go to the faculty instructors for the engineering and social work classes. Their tireless work motivated us in our endeavors, not only making us better professionals, but better people. Our acknowledgments would not be complete without extending our deepest gratitude to Mary Leah Neill. Her outstanding seamstress skills helped make our design what it is today.

REFERENCES

1. Dedra Standish, Personal conversations, September-December, 1995. Rosedale, AISD, Austin, TX.

2. C.S.R. Stanford, Dorsiflexion of the Foot of an Incomplete Spinal Cord Injury Individual in Response to Vibratory Stimulus, University of Texas at Austin, 1991.

3. K.T. Ulrich and S.D. Eppinger, Product Design and Development, McGraw-Hill, Inc., New York, 1994.

Jeffery L. Norrell Department of Mechanical Engineering The University of Texas at Austin ETC II 4.164A, Austin, Texas 78712-1063 (512) 471-7347, norrell@shimano.me.utexas.edu