Inclined surface locomotion strategies for spherical tensegrity robots

Chen, Lee-Huang; Cera, Brian; Zhu, Edward L.; Edmunds, R. David; Rice, Franklin; Bronars, Antonia; Tang, Ellande; Malekshahi, Saunon R.; Romero, Osvaldo; Agogino, Adrian; Agogino, Alice M.

doi:10.1109/iros.2017.8206380

Cited by 27 publications

(21 citation statements)

References 18 publications

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“…Recent work has, for instance, explored hand-picked strategies for the quasi-static locomotion of a cable-actuated tensegrity on inclined surfaces. 61 Our own ability to harness tensegrity vibration to induce large-scale and dynamic structure offers a compelling and promising method of discovering much more dynamic gaits for these environments. Indeed, our robot design is already capable of interesting behavioral diversity, including several unique rolling behaviors, which might be beneficial across environments—however, we were unable to explore these more deeply due to the tethered nature of this design.…”

Section: Discussionmentioning

confidence: 99%

Adaptive and Resilient Soft Tensegrity Robots

Rieffel

Mouret

2018

Soft Robotics

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Living organisms intertwine soft (e.g., muscle) and hard (e.g., bones) materials, giving them an intrinsic flexibility and resiliency often lacking in conventional rigid robots. The emerging field of soft robotics seeks to harness these same properties to create resilient machines. The nature of soft materials, however, presents considerable challenges to aspects of design, construction, and control—and up until now, the vast majority of gaits for soft robots have been hand-designed through empirical trial-and-error. This article describes an easy-to-assemble tensegrity-based soft robot capable of highly dynamic locomotive gaits and demonstrating structural and behavioral resilience in the face of physical damage. Enabling this is the use of a machine learning algorithm able to discover effective gaits with a minimal number of physical trials. These results lend further credence to soft-robotic approaches that seek to harness the interaction of complex material dynamics to generate a wealth of dynamical behaviors.

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Section: Discussionmentioning

confidence: 99%

Adaptive and Resilient Soft Tensegrity Robots

Rieffel

Mouret

2018

Soft Robotics

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“…Moreover, the methods can be used to estimate the maximum ground inclination the robots can manage or to compute actuation policies to overcome a certain inclination, which is an ongoing research topic in the field. 58…”

Section: Rolling Locomotion Of Spherical Tensegrity Robotsmentioning

confidence: 99%

Rolling Locomotion of Cable-Driven Soft Spherical Tensegrity Robots

Kim

Agogino

2020

Soft Robotics

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Soft spherical tensegrity robots are novel steerable mobile robotic platforms that are compliant, lightweight, and robust. The geometry of these robots is suitable for rolling locomotion, and they achieve this motion by properly deforming their structures using carefully chosen actuation strategies. The objective of this work is to consolidate and add to our research to date on methods for realizing rolling locomotion of spherical tensegrity robots. To predict the deformation of tensegrity structures when their member forces are varied, we introduce a modified version of the dynamic relaxation technique and apply it to our tensegrity robots. In addition, we present two techniques to find desirable deformations and actuation strategies that would result in robust rolling locomotion of the robots. The first one relies on the greedy search that can quickly find solutions, and the second one uses a multigeneration Monte Carlo method that can find suboptimal solutions with a higher quality. The methods are illustrated and validated both in simulation and with our hardware robots, which show that our methods are viable means of realizing robust and steerable rolling locomotion of spherical tensegrity robots.

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“…Physically accurate simulation of the motion requires significant computational effort for propagation of a detailed dynamical model. For this reason, most of the past work has used simpler models to reason about the static stability of the vehicle and determine shape changes that result in gravity-induced locomotion (Caluwaerts et al, 2014; Chen et al, 2017; Kim et al, 2015).…”

Section: Kinematic Computations For Primitivesmentioning

confidence: 99%

“…These benefits have motivated ongoing work on the design, simulation, and hardware prototyping of tensegrity robots (Caluwaerts et al, 2014;Skelton and de Oliveira, 2009). Multiple behaviors have already been demonstrated: crawling (Mirletz et al, 2015a;Paul et al, 2006), swimming (Bliss et al, 2013), rolling locomotion (Iscen et al, 2014;Kim et al, 2015), ascending inclines (Chen et al, 2017), and deployment as compliant many-degree-of-freedom (many-DoF) joints, as in Figure 1(b). Example uses include search and rescue in disaster areas, the exploration of natural environments, exploration and cleaning of pipes and ducts (Friesen et al, 2014), and space-related applications (Furuya, 1992).…”

Section: Tensegrity Roboticsmentioning

confidence: 99%

Kinodynamic planning for spherical tensegrity locomotion with effective gait primitives

Littlefield

Surovik

Vespignani

et al. 2019

The International Journal of Robotics Research

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Tensegrity-based robots can achieve locomotion through shape deformation and compliance. They are highly adaptable to their surroundings, and are lightweight, low cost, and physically robust. Their high dimensionality and strongly dynamic nature, however, can complicate motion planning. Efforts to date have primarily considered quasi-static reconfiguration and short-term dynamic motion of tensegrity robots, which do not fully exploit the underlying system dynamics in the long term. Longer-horizon planning has previously required costly search over the full space of valid control inputs. This work synthesizes new and existing approaches to produce dynamic long-term motion while balancing the computational demand. A numerical process based upon quasi-static assumptions is first applied to deform the system into an unstable configuration, causing forward motion. The dynamical characteristics of the result are then altered via a few simple parameters to produce a small but diverse set of useful behaviors. The proposed approach takes advantage of identified symmetries on the prototypical spherical tensegrity robot, which reduce the number of needed gaits but allow motion along different directions. These gaits are first combined with a standard search method to achieve long-term planning in environments where the developed gaits are effective. For more complex environments, the various motion primitives are paired with the fall-back option of random valid actions and are used by an informed sampling-based kinodynamic motion planner with anytime properties. Evaluations using a physics-based model for the prototypical robot demonstrate that modest but efficiently applied search effort can unlock the utility of dynamic tensegrity motion to produce high-quality solutions.

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Inclined surface locomotion strategies for spherical tensegrity robots

Cited by 27 publications

References 18 publications

Adaptive and Resilient Soft Tensegrity Robots

Adaptive and Resilient Soft Tensegrity Robots

Rolling Locomotion of Cable-Driven Soft Spherical Tensegrity Robots

Kinodynamic planning for spherical tensegrity locomotion with effective gait primitives

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