RHex: A Simple and Highly Mobile Hexapod Robot

By U. Saranlı, Martin Buehler, Daniel E. Koditschek. Int. J. Robotics Res., 2001

1,472 citations recorded by the source corpus.

In this paper, the authors describe the design and control of RHex, a power autonomous, untethered, compliant-legged hexapod robot. RHex has only six actuators—one motor located at each hip— achieving mechanical simplicity that promotes reliable and robust operation in real-world tasks. Empirically stable and highly maneuverable locomotion arises from a very simple clock-driven, open-loop tripod gait. The legs rotate full circle, thereby preventing the common problem of toe stubbing in the protraction (swing) phase. An extensive suite of experimental results documents the robot’s significant “intrinsic mobility”—the traversal of rugged, broken, and obstacle-ridden ground without any terrain sensing or actively controlled adaptation. RHex achieves fast and robust forward locomotion traveling at speeds up to one body length per second and traversing height variations well exceeding its body clearance.

Subfields: Biomedical Engineering, Control and Systems Engineering

View Paper: https://www.semanticscholar.org/paper/6c9e1f46a9109e4dccc2234f59081464056f744e

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Citations in the corpus

Modular Hopping and Running via Parallel Composition (2017, background): “2.2 is motivated by the experience of iterative motor selection for X-RHex Galloway et al. (2010b) and operating-point-based selection for its predecessors.”
Adaptive Dynamic Walking of a Quadruped Robot on Irregular Terrain Based on Biological Concepts (2003, methodology): “These biological concepts were applied for the development of hexapods with high-speed mobility over irregular terrain (Saranli, Buehler, and Koditschek 2001; Cham et al. 2001).”
Neuromechanics: an integrative approach for understanding motor control. (2007, background): “In the ensuing decades, there has been an explosion of robots that have been inspired by a wide range of animals: from stick insects such as TUM (Cruse 1990; Pfeiffer et al. 1994) and the Lauron series (Berns et al. 1994; Gaßmann et al. 2001) to hexapods including RHex (Saranli et al. 2001) and Wheg”
Jumping like an insect: Design and dynamic optimization of a jumping mini robot based on bio-mimetic inspiration (2012, methodology): “Conversely, despite a nonoptimal jumping dynamics, integration of a simple catapult mechanism is applied by both the traditional wheeled robots [8–10] and novel leg-wheeled ones [11,12], helps researchers avoid the mechanical and controlling complication and allows rescue or scout robots over obstac”
RMA: Rapid Motor Adaptation for Legged Robots (2021, methodology): “Great progress has been made in legged robotics over the last forty years through the modeling of physical dynamics and the tools of control theory [36, 43, 46, 16, 56, 63, 50, 26, 28, 2, 24].”
Learning agile and dynamic motor skills for legged robots (2019, background): “Some robots are designed such that recovery is either unnecessary or trivial [48, 49].”
The Dynamics of Legged Locomotion: Models, Analyses, and Challenges (2006, background): “The same model also describes the gross dynamics of legged machines such as RHex [13] [11] [208], and as we shall show in section 5, a second template model”
Models, feedback control, and open problems of 3D bipedal robotic walking (2014, background): “The role of compliance in locomotion on uneven terrain has been emphasized in [71, 170, 34, 33, 66, 130].”
A biologically inspired micro-vehicle capable of aerial and terrestrial locomotion (2009, background): “Mini-WhegsTM robots are extremely fast (10 body-lengths per second) in comparison to most other legged robots, and can climb obstacles taller than the top of their bodies [36][37].”
Morphological change in machines accelerates the evolution of robust behavior (2011, neutral): “These two forms were used as they are common choices when constructing physical robots (16, 17), and similarity of results across both forms would indicate the results are not specific to any given body plan.”
Compliant leg behaviour explains basic dynamics of walking and running (2006, background): “…2001) and reveal the importance of self-stability for legged systems (Garcia et al. 1998; Kuo 1999; Seyfarth et al. 2002; Ghigliazza et al. 2003) inspiring the construction of walking (McGeer 1990; Collins et al. 2005) and running machines (Raibert 1986; Saranli et al. 2001; Cham et al. 2004).”
Adaptive Dynamic Walking of a Quadruped Robot on Natural Ground Based on Biological Concepts (2007, background): “Since 2000, several hexapod robots (Saranli et al. 2001 Quinn et al. 2001 Cham et al. 2004) have realized high-speed mobility over irregular terrain with appropriate mechanical compliance of the legs.”