WEEK 9 => 1oct - 7oct

Here are some of my progress in FYP 1 presentation … later on I will update (progress, conclusion and references) 

SLIDES :

Read More

WEEK 8 => 24Sep - 30Sep

In this week my research is about how to test the ultrasonic sensor that I have bought before.

I had met with my Co-supervisor mdm.Norhayati and we have discussed about the sensor and we come out with that I have to find some schematic diagram so we can follow it and after that we construct and test the sensor.

I have done some research and I found the simplest and some explanation about it.

As I mentioned before in week 6 ,that the ultrasonic sensor (RK1089) contains of transmitter (T) and receiver (R) and each one of them have a different circuit.

For the transmitter circuit:

Figure 1.  Schematic Diagram for an Ultrasonic Transmitter Circuit (capacitor values are in microF)

This circuit is used to transmit ultrasonic waves through air, which are intended to be picked up by a matching ultrasonic receiver. 

   

The circuit uses a 555 timer IC configured as an a stable multi vibrator, i.e., it generates a continuous signal of a set frequency as long as its reset pin (pin 4) is held high. 

  

Since the ultrasonic transducer used in this circuit is one designed to vibrate optimally at about 40 kHz, the resistor and capacitor values of the circuit were chosen such that the 555 will output a signal whose frequency is about 40 kHz. This 555 output is amplified by Q1, which drives the ultrasonic transducer.  The transducer then vibrates at 40 Khz, generating ultrasonic sound waves of that frequency.

  

If paired with a matching ultrasonic receiver, such a simple transmitter can be used as a proximity sensor, such as one that can help a robot avoid running into walls.  If used in that manner, the transmitter and receiver transducers must be positioned such that the receiver will only receive echoes of the transmitted signal and not the transmitted signal itself.

 -->> Citation:http://www.ecelab.com/circuit-ultrasonic-t.htm

For the receiver circuit:

Figure 2.  Schematic Diagram for an Ultrasonic Receiver Circuit (capacitor values are in microF)

 This circuit is used to receive ultrasonic waves from the air that were transmitted by a matching ultrasonic transmitter located somewhere else.

   

Since the ultrasonic receiver used in this circuit is one designed to vibrate optimally at about 40 kHz, the transmitter paired with this receiver must also transmit 40 kHz waves. When these waves hit the receiver, the receiver vibrates and produces electric impulses, also at 40 kHz. These electric signals are amplified by the two op amps in the circuit, the amplified output of which are fed into the 567 IC.  This is a PLL tone decoder, i.e., it outputs a signal if it detects an input that is tuned to its set frequency (40 kHz in this case).

   

One example of application of this simple receiver (if paired with a matching transmitter, that is) is as a proximity sensor, such as one that can help a robot avoid running into walls.  If used in that manner, the transmitter and receiver transducers must be positioned such that the receiver will only receive echoes of the transmitted signal and not the transmitted signal itself.

 -->> Citation:http://www.ecelab.com/circuit-ultrasonic-r.htm

 And I also found this video very helpful 

-->> Citation:http://www.youtube.com/watch?v=40amNG6heVo&feature=fvsr

Read More

WEEK 7 => 17Sep - 23Sep

In this week am planning to go to Jalan Pasar to search for some sensors and at the same time to take a look at other component that it might help me in my project.

I got in mind some sensors to search about it like (ultrasonic ,Infrared, proximity sensors and others same like I mentioned before in week 5).

Location of Jalan Pasar :

Once I have reached there I found there is some differences between my research and the reality of the market ,the shops that I have visited they don’t have a lot of information about the sensors that I have requested, so I had to risk and take a sensor and later on I can do some tests and by then I can know whether it is suitable for my project or not 

I bought ultrasonic sensor (RK 1089) RM25 …

And here are some finding for (RK 1089):

40KHz Ultrasonic Transducer Transmitter and Receiver Pair. These transducers are very useful in making various sensors for detecting obstacles and measuring distances.

Features

• Use for motion or distance sensing
• Frequency: 40kHz ±1.0kHz
• Aluminum case
• Capacitance: 2000pF ±20%
• Transmitter: bandwidth 5.0kHz/100dB, sound pressure level 112dB/40 ±1.0kHz
• Receiver: bandwidth 5.0kHz @ -75dB, min. sensitivity 67dB/40 ±1.0kHz (0dB vs. 1V µbar) R=3.9k.
• Lead length/spacing: 0.28"
• Case size: 0.30"H x 0.43" Dia.

-->> Citation:http://robokits.co.in/shop/index.php?main_page=product_info&products_id=100

Read More