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Abstract

RHex is an untethered, compliant leg hexapod robot that travels at better than one body length per second over terrain few other robots can negotiate at all. Inspired by biomechanics insights into arthropod locomotion, RHex uses a clock excited alternating tripod gait to walk and run in a highly maneuverable and robust manner. We present empirical data establishing that RHex exhibits a dynamical ("bouncing") gait-its mass center moves in a manner * This work was supported in part by DARPA/SPAWAR under contract N66001-00-C-8026. Portions of the material reported here were first presented in a conference paper appearing in the collection (Altendorfer et al., 2000). 208 Altendorfer et al. well approximated by trajectories from a Spring Loaded Inverted Pendulum (SLIP)-characteristic of a large and diverse group of running animals, when its central clock, body mass, and leg stiffnesses are appropriately tuned. The SLIP template can function as a useful control guide in developing more complex autonomous locomotion behaviors such as registration via visual servoing, local exploration via visual odometry, obstacle avoidance, and, eventually, global mapping and localization.

Fundamentals of soft robot locomotion

“…inspiration [3,16,38,90] to more faithful reproductions of the biological counterpart [43,124,143], but all robots exploit their compliant components to obtain quantitative (or qualitative) advantages. By comparing the different locomotion modalities, we can highlight the recurrent benefit of energy management.…”

A Simply Stabilized Running Model

“…Specifically, we show that a liftoff-event-triggered reset of the leg angle during flight to achieve a touchdown angle fixed at the same value for each stance phase (hereafter, fixed-leg reset) suffices for stability. Such self-stabilized SLIP gaits have already appeared in the literature [10,Figure 2], where periodic SLIP trajectories were compared to Downloaded 05/10/18 to 54.202.233.140. Redistribution subject to SIAM license or copyright; see http://www.siam.org/journals/ojsa.php experimental data, although their stability properties were not discussed.…”

“…The validation of the SLIP template is based on similarities of ground reaction forces and kinetic and potential energies between these animals running at steady state and the SLIP model with suitably adjusted parameters (see [8]; for a review, see [9]). Details of the anchor system such as pitching motion or multiple leg impacts lead to small deviations from the SLIP predictions, which can be quantified by a more detailed error analysis (see [10] and the references therein).…”

Design and fabrication of multi-material structures for bioinspired robots

“…The advantages of tuned, passive compliance and damping have not gone unremarked in robotics and several multi-legged robots have used elastic elements to store and release energy, to simplify control and increase the robustness of locomotion over rough terrain (Pratt & Williamson 1995;Altendorfer et al 2001;Iida & Pfeifer 2004;Poulakakis & Buehler 2005;Kim et al 2006;Spenko et al 2008;Scarfogliero et al 2009). However, such elements significantly increase the complexity of the robot limbs.…”

“…Indeed, when we attempt anything close to biological models, we are faced with daunting complexity at every dimensional scale. For example, the cockroach, which is the approximate model for the RHex (Altendorfer et al 2001) and iSprawl (Kim et al 2006) robots, has over 200 muscles (Full & Ahn 1995). Another example that has recently been the focus of attention is the adhesive apparatus of the gecko, which consists of a remarkable hierarchy of primarily passive compliant elements with features at length scales ranging from hundreds of nanometres to centimetres (Autumn 2006;Russell et al 2007).…”