Rotationa to translation movement conversion - WITHOUT Simscape toolboxes

Hello all,

I'm basically trying to simulate a Lead screw system, driven by a DC motor (Speed profile), on a certain stroke length. That being said, I just have the basic Simscape licence (it means No Driveline or Multi body toolboxes or licences).

I just don't know what to insert where the empty space are (see picture).

Typically, my speed profile has a trapezoidal form, I have a "Angular velocity Source" block, as well as a "Translational velocity Source" block which I don't know how to link. The gain is the pitch of the screw (in mm/rev).

If you have any idea on how to do, I'm looking forward your answers.

Thank you.

[ayoub reffai]

Hi

Please im kinda stuck on the same problem you have , i was wondering if you could help out .

[Cyril CRIER]

Hello, well the solution of Jonas below might be your way through

[ayoub reffai]

please check this one if you can , i tried everything ,

[Cyril CRIER]

I personnally can't because the version in which you saved your file is too recent. try eventually to export it in version 2020a.

And can you please explain more in detail your issue?

[ayoub reffai]

oh ok here it is

I dont know what i do wrong , but i wasted a long time trying by myself need someone else point of view or new idea

basicly the system is an electrical actuator trying to push the basket of a mobile elevating working platform

thank you

[Cyril CRIER]

Well I don't have the toolboxe Multibody so I can't run the model.

So you basically can't link a "red" link (signal) to the R point of your force source block. Why do you need this block under "L_Glissière_Corps_Tige1"?

Answer 1

[Jonas]

Doesn't it make sense to just connect the speed profile on the linear velocity source, and use a regular Simulink Gain block to do the conversion between rotational and translational?

If you want to keep having the DC-motor there - which doesn't really do all that much at the moment - you can use an Ideal Rotational Motion Sensor. That sensor output needs to be converted to Simulink (PS -Simulink Converter), use a regular Gain block and then again convert to Simscape (Simulink-PS Converter).

You will also like to add something to the output of the DC Motor, such as a Rotational Free End, or an Inertia or Friction.

[Cyril CRIER]

Hello Jonas,

Thanks for your answer.

My DC motor is modeled in an other .slx. The speed profile is just a way to simulate it for the first step.

connect the speed profile on the linear velocity source, and use a regular Simulink Gain block to do the conversion between rotational and translational?

Well in my system I have a speed as an input (I want to link my DC motor Model to tis one afterward)...

According the "Ideal Rotational Motion Sensor", I'm trying indeed to use it. However, why do you need the Gain block of Simulink when the Physical Gain block of Simscape should work?

[Jonas]

You could also use the Physical Gain block, yes. Although I have never used it, but it should work fine.

[Cyril CRIER]

Hi, well the gain block looks ok but I have an arror with the solver now (see picture).

I've got this issue since I added a second signal for the torque profile.

I don't understand this issue. Anybody got already this error?

Thanks

[Cyril CRIER]

Edit:

I figured out what the issue was with the solver. In my first attent, I created a infinite loop by connecting the C port of my Tranlational Hard stop which is also connected to the Ideal Force Source block. The solution is to connect the C port to the Mechanical reference.

Answer 2

[Franck Donnadieu]

Hello, is this model is ok for you?

[Cyril CRIER]

Hi, than you Franck. Well it looks good to me, at least for the speed conversion.

What about the unit of the "Pas" (screw thread?), is it m/turn or something like that? How did you create your subsystem? (I'm a beginner)

However, I need also to simulate the forces which are applied on the system. That's why I used a Translational Hard Stop as well as Translational Friction and a Spring. -> Can I conect a Torque source to the subsystem?

[Franck Donnadieu]

Hi Cyril, yes the unit of the "pas" is in mm. I make a document (in French) wich explain how we can do a subsystem.

I also make a model with a torque source in the entry but it's basic...

[Cyril CRIER]

Hi, that's great thank you for these informations.

Regarding your Model Systeme_Vis_ecrou, I guess I have to write 1/pas in the substystem as my input is in [N.m] and my output in [N]. Am I right?

thanks again

[Franck Donnadieu]

Yes you are right and I have already done it in the model "systeme_vis_ecrou_effort.slx".

;)

[Cyril CRIER]

Hello Franck,

I'm using your models (comming back on the topic after Holidays). I observed, by looking under the mask, that you used a Wheel and Axle block to simulate the lead screw system (for speed and for Torque).

Does it mean that the output speed is parallel to the rotational direction of the entrance? I ask because I have at the end a displacement way higher than expected. What I need is actually an output speed in the direction of the axle...

Furthermore, I'm trying to add a spring in parallel of the Torque part of the "Système Vis écrou". I'm not sure to know where I should install it. Do you have an idea?