I would like to know how to calculate the centre of gravity for three wheeled robot
I have attached an image of the triangle and shown the center of gravity.
Please let me know if the formula is right or should it be the other way round. i need to cal the weight on the three wheels when loaded and unloaded.
You can't calculate the CoG for the finished robot by calculating it for just the two dimensional form. but for a triangle, the point will be where the medians meet.
For a finished robot with batteries and all, you can ue three weight scales, one under each wheel (or a single if you can make the remaining wheels level with the scale surface at each measurement), to see how the weight distributes, but this is still in 2D and the Z-axis (upwards from where it stands) is just as important when the robot moves.
It's much more involved to find the 3D CoG.