i-Walker

Intelligent Walker: Assistive tool for the elders

The i-Walker is a robotic rollator developed in the framework of the EU funded project SHARE-it (FP6-045088). It is based on a standard walker’s frame enhanced with the following sensors: front laser scanner, 8 force sensors to detect the 3 force components in both handlebars and the normal forces of the floor, odometry and tilt sensors. The i-Walker has also been equipped with two brushless DC motors as the only actuators that serve to maintain an almost constant pushing force, independently of the path, as prescribed by medical considerations. This means that the i-Walker can compensate or help: going up and down situations, start/stop movements and left and right turns. Besides, the caregiver can tune left and right actuators in order to adapt them to the user’s needs.

The functionality of i-Walker is divided in three areas: analysis, support and navigation walker (aid to move in a well-known environment).

Analysis
The Analysis feature consists in gathering, real time information coming from different sensors: forces in the handlebars and normal forces from the floor, feet relative position towards the walker, tilt information, speed of rear wheels, mainly. The analysis of this information will allow the study about: the gait, how the patient lays onto the walker and how much force exerts on the handlebars while following a predefined trajectory.

Support
The support feature consists in applying two strategies to motors:

A helping strategy. In the normal operation of the walker, the user must apply pushing or pulling forces in the handlers to move around. The strategy of helping the user consists on relieving him from doing a determined percentage of the necessary forces.
A braking strategy. It can force the user to apply a forward pushing force in the handlers in a downhill situation instead of pulling force which can be less safe.

The amount of helping percentage and braking force in each hand can both be determined by a doctor. Both strategies are not exclusive: we can have the user pushing the i-Walker going downhill and at the same time the walker relieving him from part of the necessary pulling/pushing force to move around.

Navigation

The navigation module receives the appropriate commands from an external module in order to provide navigation support to help patient to reach a desired destination indoors. The commands consist in moderate braking for steering the walker to the right direction. The i-Walker platform can be used manually by a walking user, but is also capable of performing autonomous moving. The platform can easily be adapted to accept commands to set a desired speed from a navigation module. Autonomous moving can be useful, for instance, to drive to a parking place for charging battery and returning to the side of patient when remotely called.