This mechanism is a replacement for spherical joint with a pin (2 degrees of freedom).
Yellow output frame has 2 degrees of freedom (rotations).
When the yellow frame is horizontal, centers of spherical joints between blue pistons and the yellow frame must lay on axis of pink cross shaft to get motion independence of two pistons.
Advantage: two actuators (green cylinders) are base-grounded.
The mechanism can be applied for moving antennas.