Setting joint velocity from a plugin

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Hello all,

I'm trying to simulating an obstacle avoiding robot in gazebo. I've been following this tutorial.

The problem is that this tutorial uses in order to move the robot.

SetForce(0, torque);

The problem with that is it eventually makes robot to spin.

So i looked in API ref and found

SetVelocity(0, vel);

Code compiles just fine however, this doesn't seem to have any effect on model. So how can I set velocity of wheels from a plugin ?