How to correct "Undefined function 'mtimes' for input arguments of type 'cell'."

I am trying to estimate parameters of some ODEs that describe the velocity vector of a wheeled mobile robot using the system identification toolbox. Specifically, I am trying to solve a non linear grey box model to find these parameters.

When I run the model I get the following error:

Error using iddata/nlgreyest

Error or mismatch in the specified ODE file "threewheeledomni_modelFile."

The error message is: "Undefined function 'mtimes' for input arguments of type 'cell'."

Here is the code for the ODE, the other file is too much to copy in here:

function[dx,y] = threewheelomni_modelFile(t,x,u,alpha1,alpha2,alpha3,beta1,beta2,beta3,gamma1,gamma2,gamma3,l,r,varargin)

alpha=[alpha1,alpha2,alpha3];
beta =[beta1,beta2,beta3];
gamma=[gamma1,gamma2,gamma3];

y=x;

rotMat = [cos(x(3)),-sin(x(3)),0;sin(x(3)),cos(theta0),0;0,0,1];

J1 = [sin(alpha(1)+beta(1)+gamma(1)),-cos(alpha(1)+beta(1)+gamma(1)),-l*cos(beta(1)+gamma(1));...
    sin(alpha(2)+beta(2)+gamma(2)),-cos(alpha(2)+beta(2)+gamma(2)),-l*cos(beta(2)+gamma(2));...
    sin(alpha(3)+beta(3)+gamma(3)),-cos(alpha(3)+beta(3)+gamma(3)),-l*cos(beta(3)+gamma(3))];

J2 = [r*cos(gamma1),0,0;0,r*cos(gamma2),0;0,0,r*cos(gamma3)];


dx = inv(rotMat)*inv(J1)*J2*u;

[Walter Roberson]

Nope, the code in the zip you attached starts

function[dx,y] = threewheelomni_modelFile(t,x,u,theta0,alpha1,alpha2,alpha3,beta1,beta2,beta3,gamma1,gamma2,gamma3,l,r,varargin)

with theta0 before the alpha1

[Richard Westgarth]

Correct. Im saying that was a mistake on my part. theta0 shouldnt have been a fixed parameter, its a variable. I updated the code such that theta0 is calculated from an integral function of x(3) now I'm rolling along ok. Its also possible I attached mismatched files. Thanks for the response, you helped me solve this one by highlighting that detail.

Answer 1

[Walter Roberson]

The mlx constructs 11 parameters starting from alpha1 . However the modelFile expects 12 parameters starting from theta0

[Richard Westgarth]

theta0 should have been the 3rd element of the state vector. Silly question, sorry about that.