How to set state space model structure for system identification?

I am using the system identification toolbox to develop a continuous time state space model for 2 input one output system with disturbance component. The number of states is 1 (order = 1).

dx/dt = A x(t) + B u(t) + K e(t)

y(t) = C x(t) + D u(t) + e(t)

A is 1x1

B is 1x2

u is 2x1

C is 1x1

D is 1x2

When using the system identifaction App, it automatically assumes all matrices (A,B,C,D) are free parameters to be estimated. How can I force the C and D matrices to be the following?

C = 1;
D = [0 0]; 

Answer 1

[Rakshith Badarinath]

For anyone in the same situation, here is the solution:

opt = ssestOptions;                
opt.EnforceStability = 1;

A = 0; % initial value
B = [0 0]; 
C = 1; 
D = [0 0]; 
Ts = 0; % Continuous time
init_sys = idss(A,B,C,D,'Ts',Ts);

% Set C and D structures as fixed (use values from intialized state space
% system init_sys
init_sys.Structure.A.Free = true;
init_sys.Structure.B.Free = true;
init_sys.Structure.C.Free = false;
init_sys.Structure.D.Free = false;
init_sys.Structure.K.Free = true;

% estimate model based on the data          
constrained_stateSpace_model = ssest(your data,init_sys,opt);