Fuel consumption along constant power line | Matlab Operation on engine data | Need easier optimal method

Hi,

Can somebody suggest a simpler way of finding the fuel consumption along constant power line with as less interpolation as possible.

1. I have fuel consumption map from test bench which is measured across several speed and torque. For simplicity i create the data as below.

     w=[100:100:600]; % Speed
     t=[-150:10:150]; % Torque
     [W, T]=ndgrid(w,t); 
     FC=0.05*W.*T/1000; % Fuel consumption

2. Create power matrix

P=W.*T/1000; % Power

3. So, now i have contour plots as below.

figure(1)
[c,h]=contour(W,T,FC);
clabel(c,h)
figure(2)
[c,h]=contour(W,T,P);
clabel(c,h)

4. I want to determine fuel consumption along constant power line, or in short, i want to find FC as a function of speed (W) and brake power (P). I tried 'griddedInterpolant' as below but i get error. I think i am missing something simple? I am able to solve this by work around and using interpolation twice, but i do not want to do that.

F=griddedInterpolant(W,P,FC);

Answer 1

[Karthik]

Below is the answer.

        % ------------Given data-------------
         w=[100:100:600]; % Speed
         t=[-150:10:150]; % Torque
         [W, T]=ndgrid(w,t); 
         FC= (0.000001.*(W.^2)+0.00053.*(W)+0.005+(0.05*W.*T))/1000; % Fuel consumption.
         P=W.*T/1000; % Power
         FC_table=griddedInterpolant(W,T,FC); %create a Lookup table
         %----------------------------------------------------------

         p1=(1:1:100); %create constant power vector
         [W1, P1]=ndgrid(w,p1);
         T1=P1./W1;% determine torque at constant power.
         FC1=FC_table(W1',T1')'; %Determine fuel consumption at new torque
         [c,h]=contour(W1,P1,FC1);
         clabel(c,h);