Abstract:
This paper presents a multi-stage shared control
method (MSSC) which can be used to control the movement of
a robotic mobility assistant designed to facilitate safe
mobilization for people with unstable gait. The multi-stage
control module consists of user intent, obstacle avoidance and
fuzzy logic components. The user intent represents the person’s
commands. The obstacle avoidance component reads data
representing any obstacles in the vicinity of the assistant and
uses the Vector Field Histogram (VFH) algorithm to select a
suitable path to avoid any obstacles in the path of travel. The
fuzzy logic component is responsible for merging the user
intent and obstacle avoidance information such that the user’s
request is satisfied to the highest extent possible. When an
unsafe situation presents itself the user’s request(s) will be
partially or wholly overridden so the assistant can return to a
safe state.
The system has been designed to be dynamically
configurable so as to suit different users in terms of gait
stability and strength, preferred speed of travel and level of
control over the system. It has been tested both in a simulated
environment and real-world operating conditions and has been
shown to effectively avoid obstacles with minimal disruption to
the user and their intent.
