Grousers improve drawbar pull by reducing resistance and generating thrust at the front of a wheel. (October 2020)

• Record Type: Journal Article
• Authors: Forough Nassiraei, Amir Ali; Skonieczny, Krzysztof
• Is Part Of: Journal of terramechanics. Volume 91(2020)
• Page Start: 73
• Page End: 84
• Publication Date: 2020-10
• Subjects: Grousers -- Drawbar pull -- Planetary rovers -- Wheel design; 00-01 -- 99-00; Trafficability -- Periodicals; Praticabilité (Routes) -- Périodiques; Trafficability; Periodicals; 629.222
• DOI: 10.1016/j.jterra.2020.05.005
• Languages: English
• ISSNs: 0022-4898

Abstract

Highlights: The effects of grousers at various points on a wheel are studied experimentally. Grousers at the front of, not below, a wheel produce thrust and reduce resistance. A novel wheel is developed with a modifiable grouser tip profile. The wheel extends/retracts grousers at points along the wheel, even as it rotates. Abstract: Grousers are commonly used to increase wheel traction, though how grousers exactly influence wheel thrust and resistance, and thus drawbar pull, has continued to remain an open topic of research. This work explores rigid wheels with grousers traveling on homogeneous granular soil. Unique experiments that provide insights into what grousers are doing at various points on a wheel are presented. To perform these experiments, a novel wheel that enables grousers to extend and retract in various regions around the wheel is developed; specifically grousers can always be extended at the front of the wheel but retracted below the wheel, even as the wheel rotates. These experiments show that grousers are much more effective at increasing drawbar pull when they are interacting with soil ahead of the wheel, rather than below it. A wheel with grousers engaging soil only ahead of the wheel, and not below it, nonetheless achieves over 80% of the relative improvement in drawbar pull that a "full grouser" wheel achieves over a grouserless wheel. This reveals how thrust is generated primarily by the front-most grouser, and further suggests that the reduction of resistive forward soil flow also plays a key role in increasing drawbar pull.