  Electric-powered wheelchair plays an important role in providing
accessibility for people with mobility impairment. Ensuring the safety of
wheelchair operation in different application scenarios and for diverse users
is crucial when the designing controller for tracking tasks. In this work, we
propose a safety-based speed tracking control algorithm for wheelchair systems
with external disturbances and uncertain parameters at the dynamic level. The
set-membership approach is applied to estimate the sets of uncertain parameters
online and a designed model predictive control scheme with online model and
control parameter adaptation is presented to guarantee safety-related
constraints during the tracking process. The proposed controller can drive the
wheelchair speed to a desired reference within safety constraints. For the
inadmissible reference that violates the constraints, the proposed controller
can steer the system to the neighbourhood of the closest admissible reference.
The effectiveness of the proposed control scheme is validated based on the
high-fidelity speed tracking results of two tasks that involve feasible and
infeasible references.
