DESIGN OF A HEART RATE MONITOR
DESIGN OF A HEART.pdf (Size: 2.16 MB / Downloads: 75)
This project presents the optimal design of a health monitoring device worn during exercise--the
body heart rate monitor. The product provides the time and duration of exercise session, heart
rate of user, and calories burned during the session. The primary target market includes fitness
enthusiasts, professional and armature runners and cyclists, and heart patients.
The objective from an engineering viewpoint was to minimize overall size and weight, resulting
in an optimal size being 21 cm3 and weight being 143 g. The objective from a microeconomics
viewpoint was profit maximization, which yielded a maximum profit of $35,180,681.91 at a
demand of 100,000 units sold. In the marketing model, survey results were used to determine
user preference for product shape, size, orientation, and price. Using profit maximization, the
results indicated that the preferred product has a rectangle shape, horizontal orientation, screen
size of 4 cm by 6 cm, and the lowest possible price. The optimization results yielded a rectangle,
horizontally oriented, 4 x 6 size, and a price of $214. The optimal solution provided a profit of
$50,723,546 with a demand of 270,766 units sold.
The final aesthetic study revealed that the industrial design decisions made, according to
“familiarity”, “cohesiveness”, and “complexity,” corresponded to the users’ preferences. The
people surveyed preferred the most familiar, cohesive, and simple design. According to the
marketing survey, the golden ratio for product dimensions was preferred, which affected
engineering results by making the product larger.
The product design problem
The product that will be optimized in this project is a body monitor, used during exercise or
training, that enables wireless, free-living data collection of body vital signs. The design of the
product will include sensors that gather information about the body’s heart rate, heat flow, and
skin temperature. The product will be attached to the user’s upper arm via an adjustable strap.
The body of the product will have an output interface for the user interaction. There will also be
a power button on the product. The product will get power from batteries that are charged with a
The overall design challenge will be to minimize the size and weight of the product. In addition,
the product must be comfortable for the user and easy to understand. For user comfort reasons, a
small size and weight will be less obtrusive to everyday, all day usage. A lower weight may
limit breakage. In doing so, several tradeoffs will be made. When the size is minimized,
functionality in the computerized element will be limited. In addition, small size will demand a
smaller battery life. Small size also limits the screen size, which should be maximized for easy
visibility. Demanding a small weight requires careful material selection and product design
Heart Rate Monitor Definition
The Heart Rate Monitor is like a coach that guides you through each workout. For endurance
workouts, it paces you so you don't overdo it. For tempo runs, it keeps you on track. And for
interval workouts, it makes sure you go hard enough and you recover when it's time. It can show
you when you are dehydrating, or running out of nutrition, or not recovered from a previous
day's workout. It allows you to analyze workouts and races so you can identify your weaknesses
and turn them into strengths.
How it works
When you start training, your heart rate increases rapidly in according to the intensity of the
training. In Heart Rate Monitors, the transmitter belt detects the electrocardiogram (ECG - the
electric signal originating from your heart) and sends an electromagnetic signal to the wrist
receiver where heart rate information appears.
The heart moves blood from the lungs (where the blood picks up oxygen) to the muscles (which
burn the oxygen as fuel) and back to the lungs again. The harder the training, the more fuel the
muscles need and the harder the heart has to work to pump oxygen-rich blood to the muscles. As
you get fit, your heart is able to pump more blood with every beat. As a result, your heart doesn’t
have to beat as often to get the needed oxygen to your muscles, decreasing resting heart rate and
exercise heart rate on all exertion levels.
In order to get realistic results, additional constraints would need to be added to the engineering
model regarding design of circuit boards, processors, sensors, and product assembly. This model
was simplified in order to focus on the users’ point of view and add in the constraints that
aligned with their goals. After determining the users’ preference for a rectangular shape, it was
noted that the engineering model results compete with the preference for users to have a
rectangular product. This result is due to the fact that minimizing size and weight would result in
a square shaped product. By introducing the golden ratio into the engineering model, the size
and weight must be larger than if this constraint was not included.
The microeconomics and marketing model differ in their results for a few reasons. Firstly, the
elasticities were extreme estimates not taken from accurate statistical data about preference.
Second, the demand curve was also an estimation made without accurate data. The marketing
model data may be skewed due to ineffective survey creation and inability to provide real
physical products to those being surveyed.