Thank you for the resources! The book I've already started to go through, and the Web-U I will sign up for and watch.

You have multiple issues going on. First, your motor model is problematic because it violates the Modelica modeling concept. It is more like a Simulink model -- it is one direction only -- you put a current into the motor and it responds by accelerating its inertia, however, if I were to spin the inertia, it does not generate a current. The problem with this is that external torques are not making it back into your motor so your motor is independent of the system (which violates physics).

Is there a reason you do not want to use one of the built-in motor models? You can then control that motor with any control system you develop. (The control system can be all mathematical). If you want to make your own motor model, you need to have the output be a rotational flange and not a numerical output. If its a flange, then you have both speed and torque communicating through the flange and the motor behaves as you want.

As far as the Gyroscope models. I can explain them:

The first model is

This sets an initial rotation rate in the revolute joint so that bodyCylinger2 is spinning about its axis and gravity will move the body so that it causes rotations due to gyroscopic effects (no surprise). The second model is more subtle:

Here the second body is modeled with two blocks instead of one. bodyCylinder4 is a rigid body with no rotation that is attached to the swinging arm. The gyroscopic torques are provided by the rotor1D element. The rotor is given the same rotary inertia as the bodyCylinder (J= bodyCylinder4.I[1, 1]). It is spun up to the desired speed. By moving the base frame around, the appropriate torques are sent back to the rest of the structure. You can imagine the cylinder at the end as two concentric objects, one fixed and one rotating. While this appears less intuitive than the first example in which the body is modeled as one object, In some circumstances there can be some advantages with splitting it up and considering the torques separately.

My suggestion is to use either gyroscope model and hook your motor to the model: (file attached)

You can put a control system around the motor with blocks and sensors. Note: I chose completely random numbers for the motor so it is not what you want but it should give you a starting point.

I also put the motor on the second gyroscope example model but note that I needed to put the reaction force of the motor back into the frame or the model would not be correct.

Is this what you are looking for? Why do you want to use a "mathematical motor"? If you need a "Mathematical Motor" can't you output your motor to a rotational flange so it is more physical? (If this is what you want, I can show you an example).

Regards,

Neil

Attachments:

GyroscopeExample.mo

Hello Neil!

The flywheel motor model does indeed work fine. I guess perhaps my naming convention is confusing....sorry about that. I want to do one of two things, either:

1) Attach my flywheel_motor_model.mo, where variable J is equal to 0.00013612480196014234 to a fixed translation and Revolute in a different multibody model and then study the gyroscopic effects.

2) or I would like to attach a mathematical motor model where J is equal to 0.000013.... we can call it current_control_motor.mo, and use it to apply a torque to the objects Bodyshape + Rotor1D, which are suppose to represent just the flywheel, which are all connected on said different multibody model, so namely, an assembly of flywheel and motor connected to the different mulitbody model.

My expectations are that 1 and 2 should produce the exact same plots, which in my images they don't as you correctly say, it's likely the objects are all connected wrong and I don't get it.

In the end I want to simulate a cube satellite, with flywheels connected to motors built inside, but I'm having problems, as you say with the Rotor1D, Bodyshape and how to correctly apply my mathematical motor model's torque to these objects.

The flywheel in reality is 103mm in diameter, 6mm thick, 120g with an inertia tensor approx:

I_11 == 0.000122/2 I_22 == 0.000122/2 I_33 == 0.000122

my Expectations are

current_control_motor.mo gets a step signal, and with it connected to the Rotor1D, and Bodyshape they all begin to accelerate in unison as one assembly to the same top angular velocity, 400 1/s, in about 3 seconds.

Currently this does not happen. As you saw, the Revolute, bodyshape and Rotor1D, and current_control_motor.mo motor all have different angular velocities.

I have looked for hours at Gyroscopic3dEffects, and I don't get anywhere closer, unfortunately.