MATLAB: Are the SimMechanics joints breaking apart in the model

Question

I am trying to create a model of a piston with translational motion in the y-direction that is attached to three beams and mounted at a fixed point outside of the system (picture below).

I used: (1.) weld joint to attach the piston to beam 1 (2.) custom joint (rotational about z-axis and translational along the x-axis) to attach beam 1 to beam 2 (3.) planar joint (translational in xy-plane and rotational about z-axis) to attach beam 2 to 3 (4.) revolute joint (rotational about z-axis) to attach beam 3 to the point outside of my system

I also added a joint actuator at the planar joint and actuated it with motion. When I run the simulation my system falls apart between beam 1 and beam 2 (at the custom joint) and between beam 2 and beam 3 (at the planar joint). How can I keep the joints attached?

Answer 1

Your joints are overdefined.This Mechanism's degree of freedom must be one.I guess you thought motion allowance instead of joints degrees of freedom.I prepared diagram like this ground-Beam3:Revolute,Beam3-Beam2:Revolute,Beam2-Beam1:Revolute,Beam1-Piston:weld,Piston-Ground:Prismatic.Weld is not kinematic structure by the way.You may assume like one body(Beam1-Piston).If I have mistakes at English sorry about it.