[For the entire collection see Zbl 0547.00057.]
For a large-scale nonlinear mechanical system a set of nominal trajectories is prescribed, together with a region of allowable parameter values. The system is viewed as a set of decoupled linear time-invariant subsystems (each associated to one degree of freedom of the system) and for each subsystem a local controller is synthesized neglecting, at the first step, nonlinear coupling among subsystems. Then, practical stability, around all nominal trajectories and for all allowable values of parameters, of the global nonlinear system is tested. An iterative procedure is established to choose unique linear local controllers which can accomodate all nominal trajectories and whithstand parameter variation. If such controllers could not be found a force feedback can be implemented as a global control in order to compensate the influence of nonlinear and variable coupling. An example of a six degree of freedom industrial manipulator is presented.