Summary of Progress up to CA2

Progress so far
I started off my FYP by reading some articles that James passed to me to gain some knowledge on how the whole system is going to work as. After that, I read some information on the work done by previous FYP student, Puay Hong, so that I know where I should continue from.

My first step was to design a rough schematic for the output circuit.(click here for schematic draft 1) This involves reading all the data sheets to get to know all the pin connections, as well as the constraints and limitations while designing the PCB such as the optimum distance of some capacitors from the voltage regulators. After reading all the data sheets and choosing all components, I designed the PCB boards for separate modules.

However, sometime in week 6, after some testing, the power supply circuits do not work. So, I modified the schematic to draft 2, without including the power supply circuits. I needed to set the whole system up as soon as possible so that I can work on the control theory and let the system up running.

I did some tests on the air pressure sensor together with the amplifier to get the range of voltages the it can deliver for the microcontroller during week 7. It has some linear proportionality between the duty cycle of the air pump and the output voltage from the air pressure sensor.

During week 8, I drafted schematic draft 2 (click here) and come out with the first PCB design for the whole circuit (click here). I finished soldering all my components in week 9 and the pictures of the PCB board is available here.

I continued my project by working on the PIC firmware. Before that, I tried to make some really air-tight air bags but seems difficult. So, I got Yong Soon to help me on it.

On the week of 13, I finally got my system up and running! It works like as an automated pressure actuating system, able to maintain the air pressure at a constant level set by the set point. I used 2 piecewise linear function to map the feedback voltage to pressure, and pressure difference to output control signal which is the duty cycle.

Since I have gotten the system working, I drafted schematic v3.0 (click here) including the power supply circuits and all other add-ons such as the bluetooth module. I also designed all the PCB boards which can be seen here.

As a conclusion, I am able to get my system up running before CA2, which involves modifying the schematic up to draft 3 and 2 PCB designs.

What to do next
Next, I am going to develop the final PCB design once I verified that my system is running well. Besides that, maybe I will want to figure out a way to pump air into an air bag more efficiently, because it is not very efficient to use air pumping motors.

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