Alterations to the human locomotor system, commonly result in problems related to balance and gait stability. To address such gait dysfunctions, several mobility aids have been developed. Devices, such as Smart Walkers (SWs), in conjunction with Human-Robot Interaction (HRI) interfaces, are typically implemented. However, common HRI interfaces are not able to provide safe assistance, at the same time as, proper environment interaction and natural user interaction. In this paper is presented the implementation of a safety robust and novel HRI interface on a SW, that provides secure human-walker interaction, as well as, environment and user interaction systems. To this end, a navigation system, a people detection system, a gait cadence estimator, a user's intention detection system and several control strategies were implemented. Additionally, a preliminary validation was conducted with a healthy user.