In this paper, a new methodology is developed for safely changing the interaction dynamics of a collaborative robot. A strategy based on electromyography is proposed to distinguish operator forces from those resulting from interactions with the environment. This allows to obtain information about the operator intentions and include it into the robot control strategy for an enhanced physical human–robot interaction. The safety of the resulting variable impedance control is guaranteed by imposing the passivity of the interaction. Experimental validation shows a good performance of the proposed method and illustrates the advantages of such a strategy in cases where human, robot and environment interact with each other.