Abstract
Due to their efficient locomotion and natural tolerance to hazardous environments, spherical robots have wide applications in security surveillance, exploration of unknown territory and emergency response. Numerous studies have been conducted on the driving mechanism, motion planning and trajectory tracking methods of spherical robots, yet very limited studies have been conducted regarding the obstacle avoidance capability of spherical robots. Most of the existing spherical robots rely on the “hit and run” technique, which has been argued to be a reasonable strategy because spherical robots have an inherent ability to recover from collisions. Without protruding components, they will not become stuck and can simply roll back after running into bstacles. However, for small scale spherical robots that contain sensitive surveillance sensors and cannot afford to utilize heavy protective shells, the absence of obstacle avoidance solutions would leave the robot at the mercy of potentially dangerous obstacles. In this paper, a compact magnetic field-based obstacle detection and avoidance system has been developed for miniature spherical robots. It utilizes a passive magnetic field so that the system is both compact and power efficient. The proposed system can detect not only the presence, but also the approaching direction of a ferromagnetic obstacle, therefore, an intelligent avoidance behavior can be generated by adapting the trajectory tracking method with the detection information. Design optimization is conducted to enhance the obstacle detection performance and detailed avoidance strategies are devised. Experimental results are also presented for validation purposes.
Highlights
Over the past decades, autonomous mobile robots [1,2,3,4] have received significant attention in the robotics community and challenges related to their navigation [5,6,7] have motivated countless studies.Nonholonomic robots [8,9], being one of the vastly developed categories, have wide applications in surveillance and transportation
VIRGO [17,18] is a novel miniature spherical robot developed in Singapore University of Technology and Design (SUTD) with unique surveillance capabilities and Sensors 2017, 17, 1231; doi:10.3390/s17061231
A passive magnetic field based proximity sensor has been implemented on a robot moving speed and so on
Summary
Autonomous mobile robots [1,2,3,4] have received significant attention in the robotics community and challenges related to their navigation [5,6,7] have motivated countless studies. Navigation of mobile robots have usually been discussed in three different directions: motion planning, trajectory tracking and obstacle avoidance. Cameras and infrared sensors are widely available on the market and have been used for navigation purposes [25,26,27], sensors are widely available on the market and have been used for navigation purposes [25,26,27], their application requires a supporting pattern recognition algorithm, which would demand their application requires a supporting pattern recognition algorithm, which would considerable computational efforts and high processing capability. A magnetic proximity sensor is optimized and integrated with the robot configuration pursuit controller is adapted to handle the obstacle avoidance action by only employing data from to achieve a reasonable detection range without affecting the robot behavior. Performance is verified against the ground truth using an optical motion capture system
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