Joint shaking

I create a four bar robot,and add articulation joint to every revolute joint except the last joint,when i start the simulation and drag the drive ,i found the last joint a little shaking.Other joint is fine .Is that a software problem?if not,how can i fix that?

In your PhysicsScene, can you change the solver type from PGS to TGS?
TGS is generally more stable for articulations

I have tried,it works.Thank you very much.Can you tell me the differences between PGS and TGS?