Dynamic multi-domain bipedal walking with atrias through SLIP based human-inspired control

Hereid, Ayonga; Kolathaya, Shishir; Jones, Mikhail S.; Why, Johnathan Van; Hurst, Jonathan; Ames, Aaron D.

doi:10.1145/2562059.2562143

Cited by 49 publications

(44 citation statements)

References 21 publications

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“…We begin by introducing hybrid (control) systems (also referred to as systems with impulse effects [13,14]). We consider hybrid systems with one domain because the specific biped models considered in this paper applies to flat-footed walking; for more complex foot behavior, more elaborate hybrid systems must be considered [6,12,14,15,20,38].…”

Section: Bipedal Robot Models Walking Gaits and Physical Constraintsmentioning

confidence: 99%

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First steps toward formal controller synthesis for bipedal robots with experimental implementation

Ames

Tabuada

Jones

et al. 2017

Nonlinear Analysis: Hybrid Systems

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Bipedal robots are prime examples of complex cyber-physical systems (CPS). They exhibit many of the features that make the design and verification of CPS so difficult: hybrid dynamics, large continuous dynamics in each mode (e.g., 10 or more state variables), and nontrivial specifications involving nonlinear constraints on the state variables. In this paper, we propose a two-step approach to formally synthesize controllers for bipedal robots so as to enforce specifications by design and thereby generate physically realizable stable walking. In the first step, we design outputs and classical controllers driving these outputs to zero. The resulting controlled system evolves on a lower dimensional manifold and is described by the hybrid zero dynamics governing the remaining degrees of freedom. In the second step, we construct an abstraction of the hybrid zero dynamics that is used to synthesize a controller enforcing the desired specifications to be satisfied on the full order model. Our two step approach is a systematic way to mitigate the curse of dimensionality that hampers the applicability of formal synthesis techniques to complex CPS. Our results are illustrated with simulations showing how the synthesized controller enforces all the desired specifications and offers improved performance with respect to a classical controller. The practical relevance of the results is illustrated experimentally on the bipedal robot AMBER 3. High-level motion primitives were used on MABEL to allow walking over rough ground without tripping. While tools for automatic low-level control algorithm synthesis are well developed, at the state machine level, all tuning was done by hand for lack of appropriate tools. "Probable correctness" was established through extensive simulation and experiments.

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Section: Bipedal Robot Models Walking Gaits and Physical Constraintsmentioning

confidence: 99%

“…The notion of PHZD allows for the construction of a hybrid system model for the reduced order dynamics defined by the surface (15). In particular, we reformulate the constructions in [35] in a way applicable to full-actuation [2].…”

Section: Dimension Reduction Through Controlmentioning

confidence: 99%

First steps toward formal controller synthesis for bipedal robots with experimental implementation

Ames

Tabuada

Jones

et al. 2017

Nonlinear Analysis: Hybrid Systems

Self Cite

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“…Without any torque input, passive walking robots can save the energy from previous step and walk forward. Another model that represents energy efficient walking, called the SLIP model, has also been studied [32,17], in which the robots can save energy by springing into the next forward step. On the other hand, Zero Moment Point (ZMP) is the most popular approach in bipedal robotics [19,35,36].…”

Section: Introductionmentioning

confidence: 99%

Control barrier function based quadratic programs with application to bipedal robotic walking

Hsu

Ames

2015

2015 American Control Conference (ACC)

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122

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This thesis presents a methodology for the development of control barrier functions (CBFs) through a backstepping inspired approach. Given a set defined as the superlevel set of a function, h, the main result is a constructive means for generating control barrier functions that guarantee forward invariance of this set. In particular, if the function defining the set has relative degree n, an iterative methodology utilizing higher order derivatives of h provably results in a control barrier function that can be explicitly derived. To demonstrate these formal results, they are applied in the context of bipedal robotic walking. Physical constraints, e.g., joint limits, are represented by control barrier functions and unified with control objectives expressed through control Lyapunov functions (CLFs) via quadratic program (QP) based controllers. The end result is the generation of stable walking satisfying physical realizability constraints for a model of the bipedal robot AMBER2.

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“…While recent work in the field has yielded a growing array of impressive legged platforms capable of steady-state dynamic behaviors over flat or modest terrain [1,2,3,4], there has been less focus on designing systems for locomotion in highly irregular environments. In particular, there has been relatively little experimental investigation into the locomotion prowess of non-conventional legged robot morphologies (departing from the traditional rigid-body-with-appendages framework) such as core actuation that are commonly seen in animals operating in unstructured terrain.…”

Section: Introductionmentioning

confidence: 99%

Core Actuation Promotes Self-manipulability on a Direct-Drive Quadrupedal Robot

Duperret

Kramer

Koditschek

2017

Springer Proceedings in Advanced Robotics

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For direct-drive legged robots operating in unstructured environments, workspace volume and force generation are competing, scarce resources. In this paper we demonstrate that introducing geared core actuation (i.e., proximal to rather than distal from the mass center) increases workspace volume and can provide a disproportionate amount of work-producing force to the mass center without affecting leg linkage transparency. These effects are analytically quantifiable up to modest assumptions, and are demonstrated empirically on a spined quadruped performing a leap both on level ground and from an isolated foothold (an archetypal feature of unstructured terrain). Abstract. For direct-drive legged robots operating in unstructured environments, workspace volume and force generation are competing, scarce resources. Disciplines Electrical and Computer Engineering | Engineering | Systems EngineeringIn this paper we demonstrate that introducing geared core actuation (i.e., proximal to rather than distal from the mass center) increases workspace volume and can provide a disproportionate amount of work-producing-force to the mass center without affecting leg linkage transparency. These effects are analytically quantifiable up to modest assumptions, and are demonstrated empirically on a spined quadruped performing a leap both on level ground and from an isolated foothold (an archetypal feature of unstructured terrain).

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Dynamic multi-domain bipedal walking with atrias through SLIP based human-inspired control

Cited by 49 publications

References 21 publications

First steps toward formal controller synthesis for bipedal robots with experimental implementation

First steps toward formal controller synthesis for bipedal robots with experimental implementation

Control barrier function based quadratic programs with application to bipedal robotic walking

Core Actuation Promotes Self-manipulability on a Direct-Drive Quadrupedal Robot

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