Virtual Landmark-Based Control of Docking Support for Assistive Mobility Devices

TL;DR

This paper introduces a novel autonomous docking control method for assistive mobility devices using virtual landmarks and FOV constraints, validated through simulation and real-world experiments on a wheelchair.

Contribution

It presents a new nonlinear feedback control approach for virtual landmark-based docking with FOV constraints, including a feasible space analysis and real-time implementation.

Findings

Guaranteed convergence within the feasible space.

Successful real-time docking on a standing wheelchair.

Effective virtual landmark estimation via 3D object tracking.

Abstract

This work proposes an autonomous docking control for nonholonomic constrained mobile robots and applies it to an intelligent mobility device or wheelchair for assisting the user in approaching resting furniture such as a chair or a bed. We defined a virtual landmark inferred from the target docking destination. Then, we solve the problem of keeping the targeted volume inside the field of view (FOV) of a tracking camera and docking to the virtual landmark through a novel definition that enables to control for the desired end-pose. In this article, we proposed a nonlinear feedback controller to perform the docking with the depth camera's FOV as a constraint. Then, a numerical method is proposed to find the feasible space of initial states where convergence could be guaranteed. Finally, the entire system was embedded for real-time operation on a standing wheelchair with the virtual landmark estimation by 3D object tracking with an RGB-D camera and we validated the effectiveness in simulation and experimental evaluations. The results show the guaranteed convergence for the feasible space depending on the virtual landmark location. In the implementation, the robot converges to the virtual landmark while respecting the FOV constraints.