pendulum with air resistance in simulink

I'm trying to recreate a pendulum wave through a scope in simulink.

Consider the following formula:

with g = 9.81 (gravity on earth), L = 1 and mu = 0.1

I got the following model:

Since I'm new to Matlab, I'm not sure if my model is correct, corresponding to the equation.

[Fangjun Jiang]

Correct

[Nicolas]

Hello !

I wanted to recreate this pendulum with air resistance to test out other things but i can't manage to do it. Can you share me the .mlx project if you still have it ?

Kind regards

Answer 1

[Sam Chak]

Hi @Jordi van Selm

Yes, your model is correct. In fact, the pendulum equation can be rewritten as a system of 1st-order ODEs:

where and are the system state variables. In Simulink, the system is interpreted in integral form

You can use two Integrator blocks, or a single Second-order Integrator block as shown below. The inner loop is the angular velocity loop and the outer loop is the angular position loop.

You can also send the signals to MATLAB Workspace for plotting out the result for your technical report.

Note: If the system is linear, then you can directly use the Linear State-Space Model Block without the Integrator blocks.

[Nicolas]

Hello !

I wanted to recreate this pendulum with air resistance to test out other things but i can't manage to do it. Can you share me the .mlx project if you still have it ?

Kind regards