Alexandre René Lemay, Cameron Ayles, and Viraaj Patel,
Mechanical Engineering, University of Ottawa
The motorized horizontal blind is a complete integrated system
that opens and closes a horizontal blind with a DC motor powered
by two AA batteries.
The system can operate in either manual mode or switch to fully
automatic mode. When manual mode is selected, the control switch
operates the up or down movements only and two limits switch are
installed to stop the blinds at the top and the bottom position.
When the auto mode is selected, the system is controlled by the
Arduino Uno Microcontroller board and the photo sensor.
blinds will move automatically to the up position if the photo
sensor detects enough light and will stop when it reaches the
upper limit switch and vice versa, if the photo sensor does not
receive enough light, the blind starts its decent and operates
in the down movement until it reaches the lower limit switch
then the blind stops, therefore fully closing the blind.
All the components were purchased at the local Home Depot
hardware store as well as several electronics shops such has
Gervais electronics, The Source, Active Tech Electronics, The
Robot Shop and the Hobby House Ltd in Ottawa.
Electric, Software and Electronic Components
blind motor is a 6-speed gearbox motor assembly. The gear ratio
selected for this project was 505.9:1.This gives 19.9 (rev/min) with a torque of type RE 260
motor (3V) 226.1 (mN-m).
electric motor is powered by a set of 2 AA ( 1.5 Vdc batteries)
of 3Vdc total output in the manual or auto mode.
Arduino Uno Microcontroller Rev 3 board is use to operate the
electrical relay, the photo sensor, the threshold for the light
sensitivity of the photo sensor.
The Arduino board is
program using its supplied operating software downloaded from
the internet and configured for this project. Also the Arduino
board is powered by the Laptop computer using
the USB port.
locatedat the top
and at the bottom of the wood frame to stop the movement of the
blind once it reaches it specific position.
double pole, double throw relay switch is wired to change the
contact polarity in order to reverse the direction of the motor
to open and close the blind.
A bread board integrates all electronic components such as the
relay switch, a 1.2 KOhm resistor, a photo sensor (photoresistor)
and to create an H-bridge wiring design. Several jumper cables
are installed from the Arduino board and the bread board making
the connection assembly and the battery power source.
The photoresistor is the sensor whose resistance varies with
light intensity. It decrease in resistance as the light
intensity increases. In our microcontroller application,
this resistance convertes to a voltage so that an A2D converter
can measure it therefore using a voltage divider circuit.
voltage divider is just two resistors in series connected
between a voltage supply and ground. If
R1 is connected to the
voltage supply and R2 is connected to ground then the voltage at
the junction between the two resistors is:
If R1 is the photoresistor, the voltage will increase with
increasing light intensity.
An electrical switch box is used to incorporate the three
switches for the system. The Power switch that turn on and off
power to the system, the
rocker switch that selects either the manual or the fully
automatic operation and finally the third switch for the manual
operation to either raze or lower the blind.
The blind motor is a 6-speed gearbox motor assembly. The gear
ratio selected for this project was 505.9:1this gives 19.9 (rev/min) with a torque of type RE 260
motor (3V) 226.1 (mN-m)
The drive shaft of the motor is equipped with a plastic
spool to receive the blind string as it rotates to either raze
or lower the blind. A bolt is installed at the base of the blind
to give it weight as it hits the limit switches.
wood frame structure was constructed to assemble all the
components of the system. The complete system is mounted on a
wood frame to show how the unit would be setup in a residentialindoor operation.
Two metal brackets were installed at the top and the bottom of
the gear box assembly to absorb the torque given from the motor
and the weight of the blind.
The prototype was tested during assembly, installation and at
completion. The manual and automatic mode operated successfully.