The paper describes the "electronic" stiffening of the actuators developed for the articulated boom of JET. Experimental trials on a two joints Boom have confirmed the improvements of speed and reliability that can be achieved. Based on these developments, a new control system for the boom is now under development together with a simulator intended to make easier and faster the system commissioning, design and optimization as well as the fault identification. The main originalities of the paper are the modeling of the actuators, based on a mechanical equivalent and an extension of the Craig's computed torque method to elastic system.