Week -2
1) The simulink model of a doorbell using a solenoid was made and the physical movement of the plunger was observed for a sample period of 0 to 10 sec. The simulnk model for doorbell using solenoid is:
A 12V DC battery source is used to as a voltage source to power the solenoid. An external signal controlled switch is used to turn on and off the circuit. The external signal was provided by the continious pulse generator.
The switch will operate in such a manner that, if the external signal value is greater than the threshold value of the switch the switch will close otherwise it will open. The threshold for switch was set to 0.5.
Inorder to create a situtation where the switch is closed for 2 sec and release, The amplitude of pulse generator was set to 5 and period to 4 sec. So for 0 to 2 sec the amplitude will be 5 and 2 to 4 sec amplitude will be 0.
An ideal current sensor was used to observe the output from switch based on the condition given to the pulse generator
An ideal translational motion sensor was used to sense the position of plunger.
Result from the model after simulating for a sample period of 0 to 10 sec is:
The observation from the result is that, once the switch is closed for every 2 sec w.r.t to external signal, the position of the plunger changes and vibrates.
2) The simulink model was created for a thermistor to sense the temperature of the heater and turn on and turn off the fan for the following condition:
TEMPERATURE CONDITION: 20^0C FOR 0 TO 10 SEC, 27^0C FOR 10 TO 30, 23^0C FOR 30 TO 50 SEC
FAN CONDITION : ON IF TEMP ABOVE 25^0C, OTHERWISE OFF.
The simulink model for the system is :
The sample period for the simulation was set to 50 sec.
The temperature condition was attained using a repeating sequence stair. Here we can repeat the values of vector output inorder to attain the given condition. The sampling time was set to 10 sec.
A controlled temperature source was used.i.e we cannot give the array of input in terms of time, the control temperature source have an input and a reference and one output. The input to the source should be in kelvin, so we need to give the values of temperature in terms of kelvin in the repeating stair sequence.
A battery was provided which act as a source to the system which does not discharge over a period of time. For the thermistor to work according to the parameter it is given a resistor was connected in series with the thermistor . Based on the output from the resistor only system will work.
A switch was provided having 3 ports. 1st port on state value, 2nd off state value 3rd port is threshold. Temperature value cannot be given as threshold for the switch. so we need to give threshold value of switch in terms of voltage. So a votage sensor was used across the resistor. The threshold for the switch is given as .01189 which is a voltage value corresponding to the temperature 298.15K(25 degree celcius)
A controlled voltage source was used to provide power to the DC motor when switch is closed.
DC motor was used instead of the fan and a ideal translational motion sensor is used to sense the angular velocity of motor.
The result from the system is:
The system was worked according to the our given condition.i.e fan must be turn on when temperature is above 25 degree celcius.
For 0 to 10 sec, the DC motor is not rotating. Angular velocity is equal to zero. Temperature was 20 degree celcius which is less than 25 degree celcius, so the switch was open
For 10 to 30 sec, the DC motor is rotating with angular velocity of 1.454 rad/sec. The temperature 27 degree celcius is greater than 25 degree celcius, so the switch was closed.
For 30 to 50 sec, the DC motor is not rotating. Angular velocity is zero. The temperature 23 degree celcius is less than 25 degree celcius, the switch was open