Gazebo simulation of a suspended robot / control and gravity problem

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Hello everyone,

I am trying to simulate the robot example in Gazebo, seen in the picture. It is a suspended robotic arm. It should translate along vertical axis, with distance d adjustable by the user (controllable).

C:\fakepath\126210014_3694965843894947_9110529226508171826_o.jpg

I have created a prismatic link between the base frame (base link) and the fixed frame. However, when I start Gazebo, the robot goes everywhere.

I disabled the gravity for all links. But, the base link gravity is added automatically. I want also to solve this issue.

Ps: I have to use .yaml files for control.

I really need some help, advices to solve this problem. I am so thankful for any help.