spherical joints HELP

[dinko_stz]

Hi
I have a problem with CATIA V5. I'm trying to make D MU kinematics mock-up, but i can't definite a spherical joint. If anyone can help to solve this problem I'll be very happy. I can't find any tutorial for a spherical joints.

 

[MrCATIA]

There is a short description of Spherical Joints in the online Help.

A Spherical Joint is pretty easy to add to a kinematic mechanism - just select two points (the centerpoint of the ball, and the centerpoint of the socket)

 

[dinko_stz]

There is a short description of Spherical Joints in the online Help.

A Spherical Joint is pretty easy to add to a kinematic mechanism - just select two points (the centerpoint of the ball, and the centerpoint of the socket)

Yes that's correct. But after that when i try to make simulation it's impossible. I have 3 DOFs! How to fix them?

 

[MrCATIA]

Mechanisms must have 0 DOF before they can be simulated.

So, you need to define more joints, or add some commands, or a combination of both.

I'm not sure what your mechanism is, so I'll guess you only have two parts: the ball, and the socket. Adding the Spherical Joint locks in the three translation DOF, but the parts are still free to rotate in 3 directions. More parts are needed to define how the ball is supposed to behave, along with an input command to drive the mechanical motion.

 

[dinko_stz]

Thank you for the info. It was very useful. I'm trying to make a simulation of Delta Robot. I added all parts who was need to finish the robot. As a result i had 0 DOF but still couldn't move it. CATIA presented me that i had too many commands but i had only 3 revolute commands. When I stooped 2 of the commands I could move the robot but only vertical. It still couldn't move like a real Delta robot whit correct spherical joints. If someone did such simulation will be good to share him experience!

 

[MrCATIA]

View attachment 833

I found several pictures of Delta Robots, such as this one above

There are three input angles which would match the 3 commands you described in the first post.

But I only see Revolute joints - no spherical joints.

 

[dinko_stz]

I saw this kind of delta-robot only with revolute joints. It can make easy. But actually I succeeded to make it whit spherical joints. I added an universal joint to every spherical joint. I made and simulation too. Everything was moving correctly.