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Voice-operated and proximity lift controls
One big problem with lifts is that
you usually have to press a button to
select which floor you want to go to.
And with everyone pressing these buttons, there is the possibility of spreading disease. So I came up with these
voice-operated controls for the service
lift at my workplace.
It takes a voice command from people inside the lift and converts them
into electrical signals which operate
solenoids to press the lift buttons.
To call the lift, one or two proximity
sensors are provided at each floor,
for up & down. All you need to do
is wave your hand near the sensor to
call the lift.
This project can handle other voice
commands, such as opening and closing doors, controlling a fan or triggering an alarm. A laptop with an Intel
Core i3 processor handles the voice
recognition, passing commands to the
Arduino via a USB connection.
Within the lift, nine solenoid thimbles placed on the control switch
touchpad operate the buttons. This
is attached to the lift using a 160mm
x 10mm wire frame on top of the lift
command keypad. A technician from
54
Silicon Chip
the turbine maintenance department
made the small cage-like solenoid
holding pads which push the switch
pads.
After receiving a command, the
machine speaks out the intercepted
command and then executes the command to actuate the right solenoid to
press the button. This is handled by
the Arduino triggering a transistor to
drive the solenoid coil using one of its
digital outputs.
Commands are supported in English
and Hindi, including “first floor”/“ek
number”, “second floor”/“do number”, “third floor”/“teen number” and
“fourth floor”/“char number”. If the
command is not understood, it will
ask for you to repeat it.
Arduino digital outputs D5-D13
provide the following functions, in
order: fan stop, fan start, alarm, door
open, door close, first floor, second
floor, third floor and fourth floor. The
extended commands “pankha chalu”/“fan on”, “pankha band”/“fan
on”, “darvaja kholo”/“door open”,
“darvaja band”/“door closed”, “ghanti”/“alarm” are used for the other commands on digital outputs D5-D9.
Australia’s electronics magazine
The software running on the PC
was developed using Python and
Google Speech. Its source code (plus
the Arduino program that it controls)
is available at siliconchip.com.au/
Shop/6/5780
The solenoids are powered from a
5V 2A plugpack, while the Arduino
is powered from the laptop’s USB 5V
supply. As the solenoid driver transistors are on the low side, 12V or 24V
solenoids could also be used with a
matching power supply.
Each solenoid has a diode, which
is normally reverse-biased, connected
across it to absorb the back-EMF spike
when it switches off.
The circuit below is much simpler,
providing the interface to call the lift.
The ATmega328 is programmed using
the Arduino IDE and it periodically
sends pulses to the two ultrasonic
distance sensors and ‘listens’ for an
echo. If it senses an object near one
of the sensors (within about 22cm),
it triggers the associated solenoid, in
much the same manner as the in-lift
circuit shown at right.
Bera Somnath,
Vindhyanagar, India. ($150)
siliconchip.com.au
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Australia’s electronics magazine
November 2021 55
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