The only general solution is to use a recursive function. Here is code which works for scalar structures, although you could extend it to include indexing into non-scalar structures.
Offset = struct('X',0,'Y',0,'Z',0);
Rot = struct('Roll',0,'Pitch',0,'Yaw',0);
IMU = struct('Offset',Offset,'Rot',Rot);
EKFerrors = struct('MeasTimeout',1,'MaxBound',3);
EKF = struct('IMU',IMU,'Errors',EKFerrors,'InitMode',2);
Z = myfun(EKF)
function C = myfun(S)
assert(isstruct(S),'Input <S> must be a structure.')
assert(isscalar(S),'Input <S> must be scalar.')
C = {};
recfun(S,inputname(1))
%
function recfun(A,N)
F = fieldnames(A);
for k = 1:numel(F)
T = sprintf('%s.%s',N,F{k});
B = A.(F{k});
if isstruct(B)
assert(isscalar(B),'Structure <%s> must be scalar.',T)
recfun(B,T)
else
C{end+1,1} = T;
end
end
end
end
