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• Tensegrital wheels built of space-qualified materials can diffuse loads like tires. • Maintaining a class 1 tensegrity design is critical to reap benefits of tensegrity. • Discrete wheel designs offer high redundancy and opportunities for internal sensing. • Tensegrity systems should be designed holistically for best outcomes. This paper follows ProtoInnovations' development of a line of novel wheel concepts built with tensegrity principles for planetary mobility. The goal of these tensegrital wheels for enhanced planetary surface mobility is to exploit the geometric and mechanical attributes of tensegrity to mimic the compliant and load-distributing properties of a pneumatic tire using space-qualified methods and materials. In this paper we present our tensegrity design process and the evolution of our tensegrital wheel concepts. We conclude with an exploration of the tensegrital wheel's potential with regards to planetary exploration applications and summarize considerations and improvements for future tensegrital wheel research. [ABSTRACT FROM AUTHOR]

• Continuous tractive surfaces on discrete wheel designs improve performance. • Maintaining a class 1 tensegrity design is critical to reap benefits of tensegrity. • Discrete wheel designs offer high redundancy and opportunities for internal sensing. • Field tests in a Martian analog demonstrate the robustness of the tensegrital wheel. This paper details ProtoInnovations' work on a novel wheel design concept for planetary mobility. The tensegrital wheel for enhanced surface mobility exploits the geometric and mechanical attributes of tensegrity to mimic the compliant and load-distributing properties of a pneumatic tire using space-qualified materials. The third iteration of these wheel concepts, dubbed the TW3, was subject to particular scrutiny. In this paper, we explore the development of the TW3 and evaluate its performance in lab tests, performed at ProtoInnovation's in-house testing facility, and field experiments, performed in conjunction with NASA Ames Research Center at the Atacama Rover Astrobiology Drilling Studies (ARADS). We compare the TW3 performance to baseline wheels and conclude with suggestions for further tensegrital wheel development. [ABSTRACT FROM AUTHOR]

• 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. 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. [ABSTRACT FROM AUTHOR]