The increased demand on robotic manipulator performances leads to the use of advanced control structures. An adaptive model following control system for robotic manipulators is developed via hyperstability theory. A new control algorithm is proposed that produces a discontinuous control signal, similar to a pulse amplitude signal, so that particular trajectories, referred as sliding modes, occur. The design procedure is simple and effective and always assures the asymptotic stability in the large. The decoupling properties can be achieved by a suitable choice of the reference model. A case study is developed by numerical simulation.