How to update during ODE45

I want get a function, which is related with motor.

[t,w]=ode45(@(t,w) -Trq/J*t, t_span, w_0)

But motor maximum torque(Trq) is related with motor speed.

Is there any method to change Trq durring ODE45??

Trq is changed by w.

Answer 1

[Star Strider]

If the relationship between torque and speed (angular veolcity) is known and can be modeled (expressed mathematically), create a function that expresses that relationship and then call it appropriately in the ODE function that is used as an argument to ode45.

.

[JUNTAE PARK]

Can you check the code?

[t,w]= ode45(@motor_trq,[0 1],w_0)

function [w_dot]=motor_trq(motor_speed , motor_torque , current_speed)

T_max=interp1(motor_speed , motor_torque , current_speed);

w_dot=T_max/J;

end

But, It throws an error,

Maybe i cannot use interp1 in the function??

[Star Strider]

‘Is this code same with below simulink model?’

I have not used Simulink in a while, so I am not certain. If it can be put into a block (and I vagurely recall doing that), it should work.

.

[JUNTAE PARK]

Thank you for reply.

But i think MATLAB code still have error. haha

[Star Strider]

The ode45 call to it has to be —

[t,w]= ode45(@(motor_speed,motor_torque)motor_trq(motor_speed , motor_torque , current_speed), [0 1], w_0)

and the other parameter ‘current_speed’ has to be present in the workspace.

.

[JUNTAE PARK]

Ah,

At first, current_speed is w_0.

and next step, current_speed should be updated from w in [t,w].

[Star Strider]

It will be necessary to create a function of ‘t’ that returns the desired output at that time and speed (angular velocity).

I leave that to you.

Experiment with it first in MATLAB, then transfer it to Simulink, if that is the desired end result.

Answer 2

[Sulaymon Eshkabilov]

This can be computed with a [for .. end] loop, e.g.:

clc;
clearvars
w = ...;
Trq = 10*w;  % E.g.
w_0 = -1.5;  % E.g.
J = 150;     % E.g.
t_span=[0, 13];   % 
for ii=1:numel(Trq)
[t,ww]=ode45(@(t,w)(-Trq(ii)/J*t), t_span, w_0);
plot(t,ww), hold all
Time{ii}=t;
W{ii} =ww; 
end

[JUNTAE PARK]

Trq is function of w.

I think this code is not reflect the T=f(w)..