Articulations : which technique to use on small constructions for sturdiness? So I have been using LEGO® for a rather long time and over the years, I started going towards small constructions. While doing this, I began building rather small robots (Mobile Frames for those who know), between ~8cm and ~11cm or approximately 8 to 11 studs.

Those mechs I build are articulated and I want them to have as many articulations as possible (e.g. a leg should have a hip, a knee and an ankle, not only a hip). 
The problem is the sturdiness of the whole construction. I have tried multiple options and the articulations are often either too weak to stay in position correctly or too fragile to support other parts, leading to structure vulnerability and eventually destruction of either portions of or the whole robot.

My question is the following : do you know any compact yet sturdy articulation building technique or any small articulation part ? 
Bonus : if you can provide a method allowing me to build more or less on the articulation (not sure if that's very clear).



EDIT : For posing reasons, the articulation needs to have some 'friction' to keep a specific angle.



Should there be any problem with the question (wrong formulation, bad English, need for clarification), please don't hesitate to point it out.
The AT-ST &amp; Endor (9679) uses cogged connectors (4210884 + 4211803, I don't know if the combination of both parts has a name) for the legs. These connectors are pretty strong for their size, they may be sturdy enough for your model if it's not too heavy.





For bigger constructions and higher degrees of freedom, beam with balls and cups can be used, they allow rotations and movements in two axis. For example, the Beam A 5M Ball/Cup Ø10.2 (they are other similar parts on Bricklink):



For example, General Grievous (75112) arms and legs can be adjusted in many ways: