Monocular Vision-based Estimation of Wheel Slip Ratio for Planetary Rovers in Soft Terrain

doi:10.3901/JME.2020.02.077

Abstract

Abstract: Estimation of wheel slip ratio is of tremendous significance for planetary rover's mobility control, it can help rovers to navigate and prevent wheels sinking into soil. A model for estimation of wheel slip ratio is built through analyzing wheel-terrain images acquired at two at two adjacent moments. A method for estimating wheel slip ratio only using visual means is proposed. The high-brightness weak boundaries of wheel ruts in the wheel-terrain image are extracted. Wheel forward displacement and line speed are estimated using the wheel ruts boundaries in wheel-terrain images acquired at two adjacent moments. A method for extracting mark points of the wheel in the wheel-terrain image is proposed. Wheel rotation angle and angular velocity are estimated using the wheel mark points in the wheel-terrain images acquired at two adjacent moments. Another method for estimating slip ratio using encoder and wheel-terrain images is presented. Two methods are experimentally tested and the results show that the two methods are both effective. The estimation errors of the slip ratio of both two methods are less than 9%. The estimation methods for slip ratio can help rovers to detect the wheel slip ratio based on the wheel-terrain images that can be used to detect the wheel sinkage, and thus improve the number of wheel-motion-state information acquired from the wheel-terrain images.

Key words: slip ratio detection, visual detection, planetary rover, extraction of weak edges in images

CLC Number:

V448

Lü Fengtian, GAO Haibo, LI Nan, DING Liang, DENG Zongquan, LIU Guangjun. Monocular Vision-based Estimation of Wheel Slip Ratio for Planetary Rovers in Soft Terrain[J]. Journal of Mechanical Engineering, 2020, 56(2): 77-85.

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