Effective Safety Strategy for Mobile Robots Based on Laser-Visual Fusion in Home Environments

Abstract

The proven efficacy of safety strategies based on 2-D laser rangefinder (LRF) strongly stimulates their application to mobile robots operating in the home environment. However, it remains a challenge for the robot to avoid collisions with all obstacles in the environment. Since LRF can only scan a horizontal slice of the world, some objects cannot be fully observed, such as tables and chairs. In this article, an effective solution based on laser-visual fusion is presented to enhance the safety of the robot. First, a vision sensor is adopted to help detect obstacles that are not fully visible to LRF. Then we propose a method to convert the depth information of the visual image into 2-D <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pseudo-laser data</i> representation. With this representation, a strategy for 2-D mapping is developed. On this basis, a novel map fusion algorithm is proposed to generate an improved grid map that amends the incorrect representation of obstacles on the traditional 2-D grid map. We further investigate a robot autonomous navigation strategy that considers LRF data and pseudo-laser data to avoid all obstacles. Experimental results show that the improved grid map together with the presented navigation strategy allows the robot not only to plan a “real” collision-free path, but also to navigate safely in both static and dynamic scenarios, and the proposed strategies can significantly enhance the performance of robot navigation in terms of safety, reliability and robustness.