World Vision, a Christian relief, development, and advocacy organization, were in need of a method of measuring weight and height of children in developing communities in order to asses malnutrition. The capstone team was given the goal to design a system or tool capable of measuring the height of a child up to five years old in centimeters to an accuracy of one decimal place.
After considering different methods of obtaining height measurements, the team concluded that infrared laser technology best satisfied the client’s functions and objectives. An overarching method that used this technology was chosen and two devices were prototyped to suit two different brackets of children – those who are able to stand (Standing Height Measurement Device), and those who are unable to stand (Laying Down Height Measurement Device). The fundamental height measurement concept integrated both electrical and mechanical equipment. The electrical components comprising of eye-safe infrared lasers, arduinos, and digital readout displays were used to measure, calculate, and display the height of the child. This process was easily completed as operation is accomplished by a simple push of a button. Also, the height measurement is easily interpreted as it displayed in the correct units and to the required accuracy. The mechanical equipment coupled with the electronics was utilized to create structural strength, durability, and portability of the device.
As the design incorporated a new means of measuring height for World Vision, a validation of concept was necessary to ensure the devices were reliable before they could be used for in-field testing. An experiment was conducted to examine the accuracy and interrater reliability of each device. Statistical analysis was performed for the collected data to present quantifiable and meaningful results that represented the success or failure of the designs. It was found that both designs were validated for accuracy, signifying that the obtained height measurements were repeatable within the means of each operators measured heights. Interrater reliability was successful for the standing device, however it proved unsuccessful for the laying down device. The team determined that machining flaws and noise presented from the lasers being in close contact with obstacles were main factors but their effects could be mitigated with further device refinement. The team recommended improvements that can be made to the existing device such as material choice and a reconfigured mount for the lasers to further develop the reproducibility between enumerators.