Collision Avoidance Safety Filter for an Autonomous E-Scooter using Ultrasonic Sensors

TL;DR

A collision avoidance safety filter for autonomous electric scooters to enable safe operation of such vehicles in pedestrian areas and employs multiple low-cost ultrasonic sensors to detect a wide range of possible obstacles in front of the e-scooter.

Abstract

In this paper, we propose a collision avoidance safety filter for autonomous electric scooters to enable safe operation of such vehicles in pedestrian areas. In particular, we employ multiple low-cost ultrasonic sensors to detect a wide range of possible obstacles in front of the e-scooter. Based on possibly faulty distance measurements, we design a filter to mitigate measurement noise and missing values as well as a gain-scheduled controller to limit the velocity commanded to the e-scooter when required due to imminent collisions. The proposed controller structure is able to prevent collisions with unknown obstacles by deploying a reduced safe velocity ensuring a sufficiently large safety distance. The collision avoidance approach is designed such that it may be easily deployed in similar applications of general micromobility vehicles. The effectiveness of our proposed safety filter is demonstrated in real-world experiments.

Figures (6)

• Figure 5: A sample distance measurement of one ultrasonic sensor and the respective filtered values. As time constants, we choose $T_\mathrm{i} = 0.79s$ and $T_\mathrm{d} = 0.03s$.
• Figure 6: Filtered measurement cones of each ultrasonic sensor and the resulting critical distance.
• Figure 7: Overview of the relevant distance variables and the different controller modes.
• Figure 8: Measurements for the experiment in Section \ref{['sec:experiments-straight']}.
• Figure 9: Measurements for the experiment in Section \ref{['sec:experiments-curves-min']}.

Theorems & Definitions (2)

• Remark 1
• Remark 2