Testing

Actual Weight vs. Measured Weight by the Scale System

The system for this test included a four strain gage sensor and display system integrated into the compression sandwich mechanism. The sensors and their interfaces were positioned and adhered to the stability mechanism and the entire mechanism was attached to the toilet bowl. The objective of this test is to determine if there is a discrepancy between the actual weight of a load and the weight measured by the system. First the system, including the sandwich, arm rests and foot supports was zeroed. This was done to ensure that the weight of the system was not included in the output. The system was then carefully loaded using weighted plates of known values. The weight output was recorded from the digital display screen and the actual weight of the plate was taken using a digital scale accurate to 0.01 lbs., for comparison purposes. For each trial the sensors were unloaded to ensure that the strain gages did not undergo plastic deformation.

Object Weighed	Think Tank Output (lbs)	Actual Weight (lbs)
25 lb weight	25.0	25.0
Person A	122.2	122.2
Person B + 45 lb weight	225.4	225.4
Person B	195.2	195.0
Person C	183.2	183.2
Person C + Person B	378.4	378.2

 

Human Subject Testing of Mechanical System:

IRB Approval:

HR-1603 "Accessible Weight Scale for Seated Users"

Recieved Expidited Approval on April 18th, 2008:

Testing Protocol:

Subjects will be approached and asked to participate through face-to-face conversation. If they are interested in participating, subjects will be given the informed consent form to sign. After the consent form is signed, the subject will be assigned a code number (known only to the principal investigator) to keep their identity private. The consent form and code number information will be stored in a locked cabinet in Cramer Hall, Room 138, which is only accessible to the principal investigator. The subject will be asked to come to Cramer Hall, Room 138, at a convenient time for a private 15-20 minute testing session. During this session, the subject will be asked to sit on a toilet (detached from any plumbing or electrical components) that has a prototype weight scale mechanism attached. The subject will be asked to adjust and use the arm and leg rests. To help simulate certain disability conditions, they will be asked to try to see how much of these tasks they could complete with one arm and while wearing thick gloves. After giving the subject ample time to adjust the arm and leg rests under various conditions, the subject will be asked to fill out a questionnaire. This questionnaire will include questions regarding the subject’s likes and dislikes regarding the prototype. Once finished, the subject will be thanked for their time and the data will be stored in Cramer Hall, Room 138. The data will only be accessible to the investigators.

Summary of Questionnaire Responses:

	Likes	Dislikes/Improvements	Changes Made After Testing
Arm Rests	Easy to maneuver and change location	A bit too stiff	Loosened bolts slightly
	Ability to operate one at a time	A locking mechanism should be incorporated	Incorporated locks in two positions so height can be changed
	Ability to lower armrest to enable transfer on/off the toilet	Should have more than one position	Added cushioning to arm rests and covered it with fabric
	Will be useful for patients who need extra support	Could be more useful if they folded backwards
	Good positioning relative to the seat	Make them more comfortable
		Should be slightly wider
Leg Rests	Good distance from the toilet	Not adjustable	Added back strap to leg rest to prevent the legs from touching the toilet and for added support
	Good height from the floor	Too close to the toilet
	Relatively comfortable	Could be used inappropriately as a step
	Supported legs well	Have more support for patient’s legs
Overall System	Easy to get on/off the system
	System easily removed from toilet

Improvements made based on IRB human subject testing results:

Based on responses from the subjects who participated in our study, we made several minor changes to our system. Locking devices were incorporated to secure the arm rests at two different upright positions. Extra padding was added to the arm rests to make them more comfortable. The bolts for the arm rests were loosened slightly so that they could be adjusted more easily. Materials were added to the leg rest to prevent the user’s legs from contacting the toilet and for added support.