MAid: A Robotic Wheelchair Operating in Public Environments

In this paper we describe the hardware design, the control and navigation system, and our preliminary experiments with the robotic wheelchair MAid (Mobility Aid for Elderly and Disabled People). MAid's general task is to transport people with severely impaired motion skills such as, for example, paraplegia, multiple sclerosis, poliomyelitis, or muscular dystrophy. Following the advice of disabled people and physicians we did not set out to re-invent and re-develop the set of standard skills of so-called intelligent wheelchairs, such as Follow Wall, FollowCorridor, PassDoorway which are commonly described in the literature. These maneuvers do not always require fine motion control and disabled people, in spite of their disability, are often well capable of navigating their wheelchair along a corridor and actually eager to do it. In our work we focused instead on maneuvers which are very burdensome because they take a long time and require extreme attention. One of these functions is deliberative locomotion in rapidly changing, large-scale environments, such as shopping malls, entry halls of theaters, and concourses of airports or railway stations, where tens or hundreds of people and objects are moving around. This function was not only acknowledged as being very useful but also very entertaining, because MAid often had to work very hard to find its way through a crowd of people. MAid's performance was tested in the central station of Ulm during rush-hour, and in the exhibition halls of the Hannover Messe '98, the biggest industrial fair worldwide. Altogether, MAid has survived more than 36 hours of testing in public, crowded environments with heavy passenger traffic. To our knowledge this is the first system among robotic wheelchairs and mobile robots to have achieved a similar performance.