You can use V-REP to learn the Inverse Kinematics: http://www.coppeliarobotics.com/helpFiles/en/inverseKinematicsTutorial.htm
ODE: OPEN DYNAMICS ENGINE (simulatore meccanico ad alto livello) http://opende.sourceforge.net/DynaMechs: An Object Oriented Software Package for Efficient Dynamic Simulation
ODE: presentation SLIDES A ODE: presentation B MANUALE
V-REP : Virtual Robot Experimentation Platform (Create, Compose Simulate any Robot) http://www.coppeliarobotics.com/OpenSceneGraph
User Manual An Example on YouTube (...and real robots)
Bubble Robot Tutorial ExternalControllerTutorial