Project Timeline
The timeline below outlines the group's design and implementation
activities throughout the term. Descriptions of each activity are detailed below.
Week
|
||||||||||
Task
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
Planning (Choose
Project, Write Proposal)
|
x
|
x
|
||||||||
Model Construction
|
x
|
x
|
x
|
x
|
x
|
x
|
||||
Mechanical
Component Assembly
|
x
|
x
|
x
|
x
|
x
|
|||||
Electrical
Component Assembly
|
x
|
x
|
x
|
x
|
||||||
Component Integration
and Testing
|
x
|
x
|
||||||||
Final report
preparation
|
x
|
x
|
||||||||
Table 1: Freshman design project timeline.
Model Construction
For physical
testing and presentation purposes, a model was made to mimic the movement of a
revolving door. A shaft with an arm was used to allow the mechanical assembly
to be operated.
Mechanical Component Assembly
For our
model, we used the following mechanical components: a DC motor, gears, bolts,
washers, and an acrylic base made in the laser cutting lab.
By conducting
timing tests on several revolving doors on Drexel campus, we estimated that the
average revolving door rotates too slowly to be used directly to generate power
with our 60rpm motor. This created the need for a way to transfer the energy from
the rotational motion of the door to the motor, while also increasing the
speed. For this reason, gears of different sizes were used in the transmission.
Gears were
selected at a 1:6 ratio so that a person using a revolving door who produces
one half of a rotation over three seconds will spin the motor at 60 rpm and
produce electricity at 12 volts. Once assembled, the gears and motor were also
tested for smooth mechanical operation.
Electrical Component Assembly
To use and
store the energy produced by the motor, an electrical assembly was designed. Since
our design goal was to store the kinetic energy in electric form while
providing power to a load, the assembly includes a battery to be charged and an
LED light. Because the target voltage for our 60rpm motor is 12V, we chose an
LED that can operate at this voltage and a battery whose potential difference
is 9V, which is lower than the motor’s output voltage. This allowed us to
charge the battery whenever the revolving door is rotated.
Because the
revolving door can be rotated in either direction, we included a diode bridge
into our electrical assembly to make sure our circuit accommodates both
revolution possibilities.
Component Integration and Testing
Preliminary
testing of the electrical components was performed on a circuit breadboard
provided by the instructor. We verified that the battery would be charged
whenever the door is rotated, regardless of the direction of rotation. We also
ascertained that the LED light would continue to be powered by the battery even
when the revolving door was not in operation.
The gears
were connected in alternating size order to increase the rotational velocity
from the door to the motor. We were also able to determine that the rate of
rotation would be increased six fold, due to the 1:6 gear ratio. To avoid
misalignment of gears, the shafts were seated in two places, in the base and
the top.
The
electrical and mechanical component assemblies were connected together and
secured in the model and tested for proper integration and operation. Testing
results showed that the model functioned successfully.
Project Budget
The project budget below shows roughly how much each of the components cost to create or purchase.
Category
|
Projected Cost
|
Mechanical
Components
|
$100
|
DC
Generator
|
$50
|
Electrical Components
|
$25
|
TOTAL
|
$175.00
|
Table 2: Freshman design project budget.
Mechanical Hardware
- Model Assembly – provides the structure for
mechanical energy input
- Gears – transmits mechanical energy from input to DC
generator
- Bolts/Washers – secures model components together
- Acrylic base – anchors model and provides structure
DC Generator
- Converts mechanical energy to electrical energy
Electrical
Components
- Battery – provides storage for electric energy
- LED – provides illumination
- Diode bridge – allows door to be spun in either
direction
