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The unprecedented pandemic that has started from December-19 in Wuhan and then spread to all over the glove, is not going to disappear soon. Touch-less devices / Voice operated systems are occupying more of industrial life spaces everyday. Their whole ecosystems like – Repairing, Checking, Buy-back, Annual Maintenance Contract is fast appearing in the market spaces next. To voice-operated-lift commands is an effort in that direction.

Voice operated Lift Command system

The service building lift is brand new and just commissioned before the nationwide lock down started in March20. Since then relentlessly the lift is in service for movement upto 4th floor. Company wide we have a policy for lift – if there is no lift operator , we will not operate any lift.

But the lift operator got infected by Covid19 and made 17 people to go for quarantined due to contact tracing associated the previous day. 

Since then the lift was kept closed for one week during which we hatched up this project. This project will take voice command from the people inside & proximity sensor from outside and then convert it into GPIO commands to operate particular solenoids to press the lift button. This project can take all the other associated commands as well like – alarm , door open, door close, fan on and fan off. 

Total nine solenoid thimbles which acts as a finger-press livers, placed on the switch touchpad of the lift using a 160mm x 10mm wire frame sitting on top of the lift command touch pad. One technician from turbine maintenance department made the small cage like solenoid holding pads which will act like puppet valve to give the push to the respective switch pad on its base. If the passenger wants to give the manual command, he will simply press the back side of the solenoid thimble of the respective floor button and the command will transfer to the lift in normal mode. 

After receiving command the machine will speak out the intercepted command and then execute the command in the form of actuating the right solenoid for the command thus pressing the button. If the command is not understood, it will speak up to reenter / re-speak the command.

Schematic: We developed this project using python by deploying the following pear models – subprocess, datetime, serial & speech_recognition. Subprocess is the python module which is used to drive the shell command containing the google_speech commands. By writing a few lines of additional codes one can make provision of saving the last audio command in an wav file. 

Speech recognition requires computer power & memory. Therefore, the more facilities are added the slower it becomes. To avoid the delay we have set up a bare minimum utility for voice operated lift commands running of an i3 grade computer. The solenoids are operated from 5 volt 2amp SMPS power therefore they are coupled with switching transistors [Z288] operating from GPIOs of the Arduino. The UNO board is getting signal from the internal serial port which then analyze & drives the respective GPIO transistors for the solenoids.

We have used NPN [2S Z288] transistor for negative switching, therefore, for higher power solenoids [12 / 24 volt ] the SPMS needs to be replaced by suitable supply voltage and the positive side of the solenoid will be connected to the 12 / 24 volt while the Arduino will be supplied with 5 Volt regulated by IC 7805.

Schematic for Lift inside:

 GPIO-5,6,7,8,9,10,11,12,13 deployed for – Fan-Stop, Fan, Alarm, D-Open, D-Close, 1st floor, 2nd Floor, 3rd Floor, 4th Floor respectively. All the bases of the transistors are negative biased by a 10K resistors from gound to avoid false energizing of the transistors. All GPIOs are connected to the base of the transistors vide a 1K resistors. Every solenoid should have a diode connected across to kill the surge voltage during switching off reverse polarity power surge.

Schematic for Lift outside:


 


Schematic for Lift outside: It’s needless to say that outside of lift there is a call button at every floor. It’s a single or double [in the intermediate floors] switch pressed by the passenger to call the vehicle in up-mode or down-mode. To cater to this requirements, we recommend one or two [depending on the intermediate floors] ultrasonic HC-SR04 based proximity switch. When the passenger takes the hand near the up sensor, it will operate the ‘UP-Lever’ and the vice-versa. Every solenoid should have a diode connected across to kill the surge voltage during switch-off.

Because we are not doing anything with the internal of the lift’s control system as supplied by the OEM, when the respective button is operated through the solenoid, the lift’s own display system takes over with all associated floor displays.

For calling the lift from outside ,one needs to take the palm within 22 cm of the respective ultrasonic sensor and the corresponding button will be pressed by the solenoid action. For the extreme floors only one ultrasonic sensor and one solenoid action is required which can be obtained by removing the corresponding solenoid. 

Software: The software is thethe life of this entire hardware system. We have two software – speech7.py & lift_command_OLED.ino 

Tid bits: Some lifts have a separate ‘STOP’ command while many has ‘STOP’ and ‘DO’ [Door Open] command clubbed into one button. In case yours is different you may have to create another GPIO-Transistor-Solenoid setup which is very easy too.

Voice Commands: First Floor, Second Floor, Third Floor, Fourth Floor, Ek number, Do number, Tin number, Char number will all give commands for 1,2,3 & 4 into the Serial terminal which will be promptly read by the Arduino-Uno to drive the respective GPIOs.If the command is not understood it will ask for re-entry of command again. 

The extended commands - pankha chalu, pankha band, darvaja kholo, darvaja band, alarm, ghanti will give commands to GPIO-5,6,7,8,9 to energize the respective power transistors to actuate the solenoids.

[In the market some devices are available in the name of speech recognition device, which cannot work for this project. Those devices are actually record your voice, train it for key pronunciations and then associate them with your chosen commands. If the speaker changes, the association also vanishes…]

Here the commands are powered by python3 speech synthesizer and associated with Google Speech command. 

For calling from outside the lift the proximity sensed actuators are developed based on HC-SR04. To call for up movement, one needs to place the hand less than 22 cm in front of the up-sensor so is for the down-sensor.

Aftermath: The unprecedented pandemic that has started from December-19 in Wuhan and then spread to all over the glove, is not going to disappear soon. Touch-less devices / Voice operated systems are occupying more of industrial life spaces everyday. Their whole ecosystems like – Repairing, Checking, Buy-back, Annual Maintenance Contract is fast appearing in the market spaces next. To voice-operated-lift commands is an effort in that direction.

Software: Included

 Somnath Bera

 Vindhyanagar / India