Modelling Backlash in Simscape Multibody Model

Hello,

I already have a multibody model of a DC motor shaft connected to a rod and rest of the components. Currently I am using a weld joint between the DC motor shaft and the rod. Now I am asked to model backlash between the motor shaft and rod, is it possible to model in Simscape Mulitbody? I knew I need to change the joint type but how do I add the backlash?

I came across a document mentioned that SimScape Multibody does not provide a function for modelling backlash (https://eprints.whiterose.ac.uk/184361/1/robotics-10-00134-v2.pdf, pg 16), is it true? If not, how can I do the modelling?

Thanks!

[Jens Schnebele]

could you just use the revolute joint : https://www.mathworks.com/help/sm/ref/revolutejoint.html

you can set limits (default this option is toggled "off") and even damping and stiffness.

Answer 1

[Shivam Gothi]

Hello @LT,

As per my understanding, you are trying to model backlash between the motor and the load shaft. You can achieve this using “simple gear” block found inside the library “Simscape / Driveline / Gears”. As shown in below figure.

Refer to the documentation for more information:

https://www.mathworks.com/help/sdl/ref/simplegear.html

As per the version history, the provision of adding “backlash” was introduced in MATLAB version R2023a.

Open the “block parameters” of “simple gear” block. You can enable the backlash by selecting“Enable backlash” checkbox, found inside “Backlash” dropdown tab. After you enable the backlash, you will be prompted to enter the backlash properties as shown in the below figure.:

Steps to simulate backlash in motor-load connection:

• Connect the motor shaft with the load through “simple gear” block.
• Set the “Follower (F) to base (B) teeth ratio (NF/NB)” property to 1.
• Enter the backlash properties as per your specifications.

Kindly refer to the below given MATLAB examples which illustrates the usage of “simple gear” block and modelling backlash.

https://www.mathworks.com/help/sdl/ug/gear-with-backlash.html

https://www.mathworks.com/help/sdl/ug/simple-gear.html

I hope this answers the question !

[Shivam Gothi]

Hello @LT,@Jens Schnebele,@MathWorks Support Team,

My answer is been marked as :

"This answer is marked as potential spam.

Administrators and moderators review potential spam—to request review please flag the answer or contact the MATLAB Central team"

What the reason behind this. I also validated the solution from my side, and the information provided in the answer are best to my knowledge. The links attached in the answers are only from Mathworks documentation and examples.

[Shivam Gothi]

Hello All,

I think the issue is resolved. Now the answer is not showing as "a potential spam".

Thanks !