Using Struct in Matlab

I need help on how to use a struct in Matlab. I need to create a function get_mas, the intent of this function is to sum the mass of all components of a rover and return the result. This function computes rover mass in kilograms. It accounts for the following chassis, power subsystem, science payload, and six wheel assemblies, which itself is comprised of a motor, speed reducer, and the wheel itself. I have attached the table of what I need to do. All i need is walk through on how to get this done. I have never used the struct feature before. Thanks a lot

[Stephen23]

@Abraham: what is your question for us?

Start by reading the documentation, and experimenting with some small examples.

Answer 1

[James Tursa]

Hints: Suppose myrover is the variable name of your rover. Then

myrover.wheel_assembly(1).wheel.mass  <-- Mass of wheel #1
myrover.wheel_assembly(2).wheel.mass  <-- Mass of wheel #2
myrover.wheel_assembly(1).speed_reducer.mass  <-- Mass of speed reducer #1
myrover.wheel_assembly(2).speed_reducer.mass  <-- Mass of speed reducer #2
myrover.wheel_assembly(1).motor.mass  <-- Mass of motor #1
myrover.wheel_assembly(2).motor.mass  <-- Mass of motor #2
myrover.chassis.mass  <-- Mass of chassis
       :
      etc

So, just type all of the masses out and add them up.

Also, consider this example which might help you with the wheel assembly masses:

>> s(1).mass = 4
s = 
1x2 struct array with fields:
    mass
>> s(2).mass = 5
s = 
1x2 struct array with fields:
    mass
>> s(3).mass = 6
s = 
1x3 struct array with fields:
    mass
>> s.mass  % <-- This syntax returns all of the masses individually
ans =
     4
ans =
     5
ans =
     6
>> [s.mass]  % <-- This syntax concatenates all of the masses into one vector
ans =
     4     5     6

Maybe you can use this syntax to make working with the multiple wheel assembly masses easier.

Your function could look like this:

% get_mas calculates the total mass of a rover vehicle
function mass = get_mas(myrover)
% put your code for calculating the total mass here
end

[Abraham]

Thank you. I was doing something like this when I couldn't find any help but now, I can use your example to modify my codes. Thanks a lot

[Stephen23]

@Abraham: you should read these:

https://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists