Axel Lankenau

A versatile and safe mobility assistant

The Bremen autonomous wheelchair implements obstacle avoidance plus driving and routing assistance in a shared-control system. This article shows how the tasks of reliably detecting obstacles in the environment and safely avoiding these obstructions are solved.

Architecture and applications of the Bremen Autonomous Wheelchair

Abstract This article presents the Bremen Autonomous Wheelchair as a platform for the realization of rehabilitation applications. In the field of assistive technologies, the necessities for safety on the one hand and adaptability to various impairments of potential users on the other hand dominate design decisions. A safe system architecture for the Bremen Autonomous Wheelchair is proposed and a hierarchy of low level application modules is presented. Furthermore, a route navigation approach that provides a high level of support is described in detail.

Safety in robotics: the Bremen Autonomous Wheelchair

Describes the development of a safety layer for an electrically driven wheelchair that is equipped with a ring of ultrasonic sensors. Designing this safety layer, which consists of software modules as well as hardware components, involved formal methods. An important outcome of the presented formal approach is a detailed set of hypotheses that specify the requirements the environment has to satisfy in order to allow the robot to behave as intended. The safety layer builds an abstraction of the real wheelchair which ensures that collisions are avoided, and guarantees that communication between software modules in a multi-PC environment takes place in real-time. As a first application on top of the safety layer, a driving wizard has been implemented. Its task is to adapt the wheelchairs speed depending on the situation of obstacles in the surrounding of the vehicle. The driver has no longer to bother with the question whether the planned trajectory will lead to a collision or not.

Safety-Relevant Mode Confusions - Modelling and Reducing Them

2-Pentanoylaminoacetic acid and pharmaceutically suitable salts thereof are claimed for use as pharmaceuticals. The compounds are useful in producing an effect on the central nervous system, especially in the treatment of various forms of epilepsy, of disninesiae, of parkinsonism, of memory troubles, of psychic troubles and of cerebral anoxia.

Ensuring safe obstacle avoidance in a shared-control system

This paper describes the Bremen Autonomous Wheelchair project. It shows that common static fire strategies for ultrasonic sensors are inherently unsafe and proposes a new adaptive fire strategy which delivers a complete coverage of the environment of the robot. Furthermore, a new obstacle avoidance approach for shared-control robotic systems is described in detail.

Ein Fahrassistent für ältere und behinderte Menschen

Dieser Beitrag beschreibt die Komponenten eines Fahrassistenten fur behinderte und altere Menschen, der auf einen kommerziell erhaltlichen Rollstuhl aufsetzt. Dabei wird sowohl auf die schnelle sensorische Erfassung der Umgebung fur eine sichere Kollisionsvermeidung als auch auf automatisches Ausweichen eingegangen, wobei die speziellen Aspekte des „Shared-Control“ hervorgehoben werden, also der Tatsache, dass sich auf dem Rollstuhl ein Mensch befindet, der nach wie vor die volle Kontrolle uber das System zu haben wunscht und bei seinen Aktionen lediglich unterstutzt, aber nicht beherrscht werden soll.

Selbstlokalisation in Routengraphen

In diesem Beitrag wird ein neues Verfahren zur absoluten Selbstlokalisation eines Roboters in einer strukturierten Umgebung vorgestellt. Da sowohl das benotigte Vorwissen als auch der Bedarf an Sensorik sehr gering sind und der Ansatz aufgrund einer gemischt topologisch-metrischen Reprasentation der Umgebung sehr gut skaliert, eignet sich die Methode fur den Einsatz in grosflachigen Service-Robotik Anwendungen. Als Experimentierplattform dient der Bremer Autonome Rollstuhl „Rolland“.