The paper deals with electromechanical systems under uncertainties and incomplete measurements. A tracking problem for the given trajectories of generalized coordinates with the given accuracy is studied. For the solution of the problem two procedures of cascade synthesis with different local feedbacks and corrective actions of observers are developed: procedure 1 with standard linear feedbacks with high gains and procedure 2 with non-linear, S-shaped sigmoidal feedbacks. Linear controls are simple to implement, but it leads to a peak effect in the beginning of a transient response and at the sudden change of external disturbances. In the second procedure restrictions on the state variables are met. It is shown that properties, which are similar to the properties of systems with discontinuous controls operating in the sliding mode, are provided in the control and observation loops via smooth and bounded signals. The decomposition of the total motion on multi-rate components and invariance with respect to disturbances with the given accuracy are provided. For these procedures the simulation results are presented.