Fall risk assessments provide a useful tool to prevent morbidity and mortality provoked by falls. Nowadays, these assessments are usually performed manually by the medical staff. This approach has three main drawbacks: i) it is time consuming, so it is only performed a few times per volunteer during their rehabilitation process; ii) it requires supervision by medical staff, so assessment at home or preferred environments is not feasible; and iii) fall risk is evaluated in a global way, so imminent fall risk is not available for decision making in assistive navigation. In this paper we propose an imminent fall risk estimator for rollator’s users that can be automatically obtained on the fly. Its main advantages are: i) it can be used in everyday conditions in any environment; ii) it does not require assistance of medical staff; and iii) it is suitable for a variety of users with minimal configuration changes. We have validated our estimator with a set of volunteers (n=10) presenting different physical and cognitive disabilities. Although the number of volunteer is limited, results show that our estimator is coherent to two traditional, well accepted assessments: the Tinetti Mobility Test and the walking speed.