# Robotics 'physics'

Hi,

I am currently working on a project where i want to import and control a robotic model. In the project i am strugling with the physics part and doubt if it is possible what i intend to achieve.

This robot (youtube link and attached picture) is controlled bij 3 separate rotating motors. the combined movement of these motors are controlling the end-effector in the bottom of the robot. Because the whole system is connected by balljoints, this is what is happening in ‘real life’ .

Controlling the 3 rotating axis by itselve is not the issue. But then, i got stuck when implementing the physings part, so that the model is actually ‘connected’. I tried playing around with physics engines like CANNON and AMMO, but at this point i don’t think this is the right way to go.

Any ideas or pointers in the right direction would be appreciated!!

thanks!

2021 eXtended eXamples see ModelAnimation - @author LA21 + Mugen87

Just thought about it once more (as I deleted my previous answer) for one sec, and it came to me - still a geometric solution:

There is a circle, with center the upper black-white joint and its axis, and radius equal to the distance from that joint to the white lever’s axis.

And there is a sphere, with center the plate’s joint and radius the length of a black arm.
It has to be a sphere instead of a circle, because the black arm also has lateral movement allowed by its balled-shaped joints when the bottom plate is pushed or pulled by the other two black pairs.

So there are 6 circles and 6 spheres. You need their intersections that will define the intermediate joint coordinates.

First move the bottom plate wherever you want inside a 3d area limited by the levers and joints, then calculate the intersection between each circle-sphere pair and choose the lower intersection points (where you’ll put the other end of the white and black arms), convert to coordinates and you’re done.

Hi,