Parallel 4-Bar linkage / Parallel link

[robzimpulse]

Hello...

i just wonder if there is any tutorial or anything related to 4 bar linkage or parallel link mechanism in v-rep?

[coppelia]

Hello,

there is no tutorial on that as far as we know.
What type of simulation are you trying to achieve? Kinematic or dynamic?
If dynamic, have a look at this page, specially the part about loop closures.

Cheers

[robzimpulse]

Hello,

i want to achieve a kinematic simulation and plot a graph from end of efector. any idea how can i build it?
so far i already make some joint and base and etc and stuck at relation between joint. where is the child joint where is the parent joint.
any idea?

thanks.

[coppelia]

The best would be to first follow the inverse kinematics tutorial.
Then, in your case, the target dummy would be fixed, and one of the linkage joints would be in passive mode (so that it won't be used during IK calculation, i.e. for the active joint).

Cheers

[robzimpulse]

Here i attach some scene with 4 Bar Linkage just like image bellow

https://www.dropbox.com/s/4qf228np5ihof ... k.ttt?dl=0

i just confuse how i assign the hierarchy of joint and if something wrong please let me know. i just want to achieve both dynamic simulation and kinematic simulation of this mechanism.

thanks.

[coppelia]

Have a look at this example of a 4 bar linkage (dynamic).

The example could have been done in a more simple fashion, but this is the correct way of doing it: when closing the loop, you could have used a simple revolute joint. The problem with that is that if your 4 joints are not perfectly aligned, you could have additional constraints blocking or hindering your mechanism. For that reason we close the loop with a spherical joint mounted on a prismatic joint.

Cheers

[robzimpulse]

Hi...

i already modified my Parallel 4 Bar according to your instruction and the result shown like image bellow.

and the object hierarchy shown as image bellow


i just confuse where do i put shape constraint so my joint2 and joint3 constrained by that shape?

here i attach my scene
https://www.dropbox.com/s/aex5lcc90l7r1 ... r.ttt?dl=0

if something wrong please let me know.
thanks

[BPLRFE]

Hello.

Very impressive software, thanks for creating and sharing it ...
I am tryíng to do a variant of the four bar linkage.
Maybe i overlooked adjusting a value or ticking a box or i just need to define the joints different
because my bars are not in the same plane. Would be great if you could take a look at my assembly (on my Dropbox-account) and give me some advice.

Thanks in advance.

Roland Frank (Germany).

[coppelia]

Hello,

you have 2 problems in your construction:

• The Prismatic_joint object is not dynamically enabled (notice the warning icon in the scene hierarchy during simulation). The reason is that the dummy-dummy link type is not correct. It should be Dynamics, overlap constraint, and not GCS, overlap constraint.
• The second problem is that object Sphere is colliding with the floor. Simplest would be to uncheck the Body is respondable flag for the Sphere.

Cheers

[BPLRFE]

Thanks, that worked.

Now i will try working out some details ...