Observation

1. System sweeps through the code every 20ms.Thus various sensor values are acquisitted

and checked for accuracy every 20ms thereby satisfying the demand for high precision

and instant error detection and correction.

2. Following table gives an description of how different modes are handled by the system.

Modes P3 sensor P3 theoretical

Output LED 1 LED2

1 No error No error P3 sensor No output No output

2 No error Error P3 sensor No output Blink

3 Error No error P3 Theoretical

Blink No output

4 Error Error Next lane Blink Blink

When both P3 sensor value and P3 theoretical value are in error, control is shifted to the

next lane.

3. (About power on self-test).

(See if this is required)

Brief explanation of our project:

As already said, our model is an observer based design with a predictive unit developed on an

empirical model.

Our system performances consists of

acquisition of data (Data being turbine pressure, NLR(speed),inlet pressure(taken as

constant at atmospheric pressure)

Conversion of data (Conversion to voltage in the range of 0-3.3v etc)

Fault detection

Isolation

Error correction using interpolation

Interrupt service routine

1. Acquisition of data:

For our project we need the values of turbine pressure and airplane speed measured in

NLR. We input that data to DECU which is LPC2148 ARM microcontroller. We also need

the value of inlet pressure. However, we conveniently assume it as constant as

atmospheric pressure value. We need these values at every sample period(i.e. every

20ms)

2. Conversion of data:

To input turbine pressure and NLR to our DECU we need to represent them in the form

of voltage in the range of 0 to 3.3V.

3. Fault Detection:

When there is an error in the input parameters i.e. Turbine pressure or NLR .our model

immediately detects the fault

4. Fault Isolation:

Fault isolation is the practice of designing systems such that when there is fault, the

negative consequences are limited in scope. Limiting the scope of problems reduces the

potential for damage and makes systems easier to maintain.

We acquire P3 and NLR values every 20 ms and when there is a fault it is detected

immediately. These make Fault isolation possible

5. Fault correction:

Based on the the datasheet which gives the relation between P3/P1 ratio and NLR,

Weve developed an interpolated expression for P3 which acts as predictive model. So

whenever a fault is detected, P3 can thus be indirectly measured.

6. Interrupt service routine:

Our controller is lpc2148 ARM, We have developed an interrupt service routine which

sweeps through the instruction set every 20ms checking for P3,inspecting possible

errors etc. It also performs power on self-check, ADC self-check etc.