How to update during ODE45

2021 11 6
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更新时间：2021 11 7
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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.

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 采纳的回答

Star Strider
Star Strider 2021-11-6

1 个投票

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.
.

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JUNTAE PARK
JUNTAE PARK 2021-11-7
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
Star Strider 2021-11-7
‘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
JUNTAE PARK 2021-11-7
Thank you for reply.
But i think MATLAB code still have error. haha
Star Strider
Star Strider 2021-11-7
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
JUNTAE PARK 2021-11-7
Ah,
At first, current_speed is w_0.
and next step, current_speed should be updated from w in [t,w].
Star Strider
Star Strider 2021-11-7
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.

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更多回答（1 个）

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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

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JUNTAE PARK
JUNTAE PARK 2021-11-7
Trq is function of w.
I think this code is not reflect the T=f(w)..

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