Lower limb exoskeletons are being used to assist people with movement disorders during activities of daily living or rehabilitation. However, providing a natural interface that automatically adapts to the patient's movement limitations remains an open challenge. In this paper, we present a control implementation that combines a compliant actuator technology with the concept of tacit learning to improve the synchronisation between the exoskeleton and the user during locomotion. We show that this implementation can be effectively used to easily modulate the joint stiffness that is perceived by the user during locomotion. This scheme set the base for the implementation of an automatically shared control between the exoskeleton and its user.