week 6

23  February 2012

This is already week 6, and I haven't chosen motor and suitable pump for my project yet. I really have to speed up, since time is running out..! i did do some research regarding the motor... and I found that stepper is the best choice for my project. I need to use motor rotating with constant step angle; which is connected to the valve. The valve will rotate and alternately open one chamber at once to deliver air in the mattress. It will then produce alternating flow of air in the mattress.

WHAT IS STEPPER MOTOR??

             Stepper motor (or step motor) is a brushless DC electric motor that can divide a full rotation into a large number of steps. Stepper motors consists of permanent magnet rotating shaft; called rotor and electromagnets on the stationary portion that surrounds the motor, called staror. Unlike the permanent magnet DC motor, stepper motors move in discrete steps as commanded by the stepper motor controller. Because of their discrete step operation, stepper motors can easily be rotated a finite fraction of a rotation. Another key feature of stepper motors is their ability to hold their load steady once the require position is achieved. 

                A stepper motor often has an internal rotor with a large number of permanent magnet “teeth”. A large number of electromagnet "teeth" are mounted on an external stator. Electromagnets are polarized and depolarized sequentially, causing the rotor to spin one "step". Full step motors spin 360o/(# of teeth) in each step while half step motors spin 180o/(# of teeth) in each step. Micro-step motors further decrease the rotation in each step. A stepper motor controller can move the electric motor one step (in either direction) by applying a voltage pulse and rotational speed is controlled by changing the frequency of the voltage pulses.  Diagram below shows one full rotation for stepper motor.

          There are several types of stepper motors. 4-wire stepper motors contain only two electromagnets, however the operation is more complicated than those with three or four magnets, because the driving circuit must be able to reverse the current after each step. Usually, people use  6-wire motor.

On 23 February, I attend a short and brief workshop conducted by Sir Zul regarding Arduino. In this two hours workshop, Sir Zul give introduction of Arduino, highlight few importance command in Arduino program, introduce several type of Arduino board; each of it has its own function and application, did some demo, and open Q&A session to ask regarding FYP.
      From this workshop, i knew that, to drive a motor using Arduino, we have to choose Arduino Romeo. it can be done by normal Arduino, but have to add H-bridge. For the Arduino to stand alone, (since student will face trouble if attached Arduino board in FYP circuit) it requires two capacitors and one oscillator, plus 5V supply, connected to Atmega 328. 

week 5

20 February 2012

Again, about the mattress, I have design the prototype, but haven’t choose the material. In my mind, I’m planning to produce something like this:

In order to produce something like this, I have to consider the type of material to be used. If I'm using 220V supply, I cannot use balloon. I also cannot use tube; because we cant see the alternating of air flow, inflate and deflate of the mattress. 

Forgetting about the mattress, now I want to focus with the circuit. I'll think again how to produce the prototype to test the pump.

Before selecting suitable motor to be used, i need to identify the system operation. From my observation, the principle of the pumping is :

:: At first, when user ON the switch, they have to set to the maximum pressure; by adjusting  the knob. Maximum pressure is about 400kpa. It is to inflate the mattress. It can be done although patient is lying on the bed. After the entire mattress is filled, users need to slow down the pressure by adjusting the knob. 

:: Motor will make the pump to suck air, and push it into the tube which is connected to the valve. The valve consists of three chamber. 

:: The valve will rotate, and pump air into the mattress at several minutes; via two other chamber. The first chamber will deliver air at several minutes to the mattress, then stop, and second tube will repeat the operation. ( in order to produce alternate flow in the mattress)

:: The process will repeat. 

Below is the image of the valve and the chamber:

Center tube is from the pump, the other two is connected to the mattress

week 4

11 February 2012

So, regarding the mattress, I think I wanna buy the existing one; which in single bed size. It is because, it is impossible for me to design the same design for the air to flow in the mattress (design for the air to flow alternately). My plan, I will try to make some modification to the mattress; to add some features such as extra deflate tubes.

single bed size mattress

After buying the mattress, i'm thinking of adding the tube, which has the same concept like the one at the buoy. The tube will be inserted at the end of the mattress, so that deflating process will be faster. Below is the picture of the deflate tube that i'm planning to add at the end of the mattress. 

Although i have to think how to insert the tube to the mattress without make any holes on it, i still proposing the idea to Mdm Naza. Unfortunately, Sir Hisyam said that it is impossible for me to add the tube at the mattress. It is because, the mattress is "sealed" at every end. How i'm going to insert it ? I'm advised to think another method, because, any mistake that i make in order to insert the  tube will cause a hole to the mattress. So, I'm advised to just producing the prototype. About the design, I have to think how to produce something that can flow alternately, with the same concept like the existing, using what material and many more ...

  

week 3

7 february 2012

As mentioned last time, I aleady went to Jalan Pasar and bought some component. For this time being, I'm focusing on my pressure control circuit. For this circuit, the component used are:

• variable resistor 500K
• MAC 97A8
• resistor and 
• capacitor 104 (0.1 nF)
• DIAC D83
• PC board

I'm planning to construct and test the circuit as soon as posibble, and move to next part. 


next, i did do some survey regarding the mattress. my plan, i want to give the supplier my spec for the mattress. because, i'm going to add up some features from existing mattress. but, generally, most of the supplier cannot produce it; due to the production is fix and done at the factory. so, it is impossible for them to take my design and produce just one piece of the mattress. because of this, i need to discuss with my supervisor regarding the improvement of the project. maybe, other add up features on the circuit, rather than at the mattress. 
:: planning to just buy the ready made mattress; which is single bed size.  below is the picture of the component that I've bought. 

week 2

6 FEBRUARY 2012

This is the 3rd week, but I did not have time to update the stuff on last week, only now I can update the stuff for the 2^nd week...

What can I say; there is not much progress on the 2^nd week. FYP briefing was held on 26/1/2012, conducted by Mdm. NorAzlina. During that meeting, Prof Zul also delivered speech on “A systemic approach for FYP.” During this briefing, students also reminded to submit the thesis and resit for claim on week 7, and reminded to update their FYP blog.

Next, I’m planning to go to Jalan Pasar to buy some electronics component for my circuit. Meanwhile, I also did do some research regarding the motor type to be used to pump the air to the mattress. Coincidentally, we have learned some motor type during class Sir Zul. I need to go through the notes and make a deep research to choose suitable motor type for this project. Hopefully, sir zul are available this week, so that I can ask for his opinion.