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

Duperret, Jeffrey; Kramer, Benjamin; Koditschek, Daniel E.

doi:10.1007/978-3-319-50115-4_14

Cited by 9 publications

(14 citation statements)

References 18 publications

(31 reference statements)

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“…High speed locomotion [6,5,20] also has similar constraints, though the energy budget for the task (in this case related to the vertical component of the velocity) is much higher. The actuator in the leg must feel touchdown without wasting too much energy (plastic collisions and damping in the leg), or consuming too much time.…”

Section: Broader Behaviorsmentioning

confidence: 99%

Actuator Transparency and the Energetic Cost of Proprioception

Kenneally

Chen

Koditschek

2020

Springer Proceedings in Advanced Robotics

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In the field of haptics, conditions for mechanical "transparency"[1] entail such qualities as "solid virtual objects must feel stiff" and "free space must feel free"[2], suggesting that a suitable actuator is able both to do work and readily have work done on it. In this context, seeking actuator transparency has come to mean a preference for minimal dynamics [3] or no impedance [4]. While such general notions seem satisfactory for a haptic interface, actuators with good mechanical transparency are now being used in high-performance robots [5, 6] where once again they must be able to do work, but are now also expected to perceive their environment by processing signals related to contact forces in the leg or manipulator when an explicit force sensor is not present. As robotics researchers develop models [7] suitable for programming behaviors that require systematic making and breaking of contact within the environments on which they perform work, actuators must be capable of: (a) generating the high forces at speed needed to accelerate the body during locomotion [5]; (b) robustness to high forces and impacts during locomotion [8]; (c) perceiving high force events quickly, such as touchdown in stance [9]; (d) perceiving contact quickly without exerting significant force on the object, such as in gentle manipulation [10]; and (e) reacting quickly during time-sensitive behaviors [11]. This work aims to describe a quantitative assay of transparency that might, for example, predict the advantage in proprioceptive tasks of an electromagnetic directdrive (DD) motor (i.e., one without gearbox), relative to actuation schemes consisting of both a motor and a geared reduction. Specifically, we explore the prospects for characterizing transparency as revealed by comparing the energetic cost of "feeling" the environment. Our sample proprioceptive task is instantiated by a simple torque estimator in Sec. 2. This scheme is then instrumented in simple contact detection experiments paired with a model to empirically explore the relationships between collision energy and detection time delay in Sec. 3. The actuators are then tested with a feel-cage task to illustrate the advantage of good transparency in Sec. 4.

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Section: Broader Behaviorsmentioning

confidence: 99%

Actuator Transparency and the Energetic Cost of Proprioception

Kenneally

Chen

Koditschek

2020

Springer Proceedings in Advanced Robotics

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“…Following [11], [12], [13], [15], [18], we propose a reduced-order sagittal-plane spined quadrupedal model consisting of two bipedal body segments connected by a massless pin joint 3 as shown in Figure 1. We take the state of the model to be given by q = (x, z, φ, ψ)…”

Section: Sagittal-plane Reduced-order Model Of Spined Quadrupedmentioning

confidence: 99%

“…The Inu robot -shown in Figure 2 and introduced in [18] -is composed of two bipedal body segments connected by a parallel elastic-actuated spine. The robot weighs 6.8kg and has a hip-to-hip length of 0.47m at full spine extension.…”

Section: Quadrupedal Platformmentioning

confidence: 99%

“…The design of the power-autonomous MIT Cheetah utilizing core actuation is presented in [15] but only simulation data Electrical and Systems Engineering Department, University of Pennsylvania, 200 South 33rd Street, Philadelphia, PA 19104 {jdup,kod}@seas.upenn.edu appears to be given. Other spined platforms exist such as the Canid robot but have only been documented executing non-steady-state tasks [16], [17], [18].…”

Section: Introductionmentioning

confidence: 99%

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Empirical validation of a spined sagittal-plane quadrupedal model

Duperret

Koditschek

2017

2017 IEEE International Conference on Robotics and Automation (ICRA)

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Empirical validation of a spined sagittal-plane quadrupedal model AbstractWe document empirically stable bounding using an actively powered spine on the Inu quadrupedal robot, and propose a reduced-order model to capture the dynamics associated with this additional, actuated spine degree of freedom. This model is sufficiently accurate as to roughly describe the robots mass center trajectory during a bounding limit cycle, thus making it a potential option for low dimensional representations of spine actuation in steady-state legged locomotion. Disciplines Controls and Control Theory | Electrical and Computer Engineering | Engineering | RoboticsThis conference paper is available at ScholarlyCommons: http://repository.upenn.edu/ese_papers/786Empirical validation of a spined sagittal-plane quadrupedal model Jeffrey Duperret and Daniel E. Koditschek Abstract-We document empirically stable bounding using an actively powered spine on the Inu quadrupedal robot, and propose a reduced-order model to capture the dynamics associated with this additional, actuated spine degree of freedom. This model is sufficiently accurate as to roughly describe the robots mass center trajectory during a bounding limit cycle, thus making it a potential option for low dimensional representations of spine actuation in steady-state legged locomotion.

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“…They enable dynamic gaits such as galloping and bounding [1], [2], reorientation maneuvers such as zero net angular momentum righting [3], [4], and can serve to increase the workspaces of the limbs for interaction. Analogously, dynamic, multi-degree of freedom robotic spines are poised to enable a myriad of new capabilities for legged robots [5], [6], [7], [8]. However, the adoption of spines in existing dynamic legged robots remains limited, in part because they introduce complicated dynamics that must be controlled, and their full range of potential locomotor benefits has not yet been characterized.…”

Section: Introductionmentioning

confidence: 99%

Coronal Plane Spine Twisting Composes Shape To Adjust the Energy Landscape for Grounded Reorientation

Caporale

McInroe

Ning

et al. 2020

2020 IEEE International Conference on Robotics and Automation (ICRA)

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Despite substantial evidence for the crucial role played by an active backbone or spine in animal locomotion, its adoption in legged robots remains limited because the added mechanical complexity and resulting dynamical challenges pose daunting obstacles to characterizing even a partial range of potential performance benefits. This paper takes a next step toward such a characterization by exploring the quasistatic terrestrial self-righting mechanics of a model system with coronal plane spine twisting (CPST). Reduction from a full 3D kinematic model of CPST to a two parameter, two degree of freedom coronal plane representation of body shape affordance predicts a substantial benefit to ground righting by lowering the barrier between stable potential energy basins. The reduced model predicts the most advantageous twist angle for several cross-sectional geometries, reducing the required righting torque by up to an order of magnitude depending on constituent shapes. Experiments with a three actuated degree of freedom physical mechanism corroborate the kinematic model predictions using two different quasistatic reorientation maneuvers for both elliptical and rectangular shaped bodies with a range of eccentricities or aspect ratios. More speculative experiments make intuitive use of the kinematic model in a highly dynamic maneuver to suggest still greater benefits of CPST achievable by coordinating kinetic as well as potential energy, for example as in a future multi-appendage system interacting with a contact-rich 3D environment.

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

Cited by 9 publications

References 18 publications

Actuator Transparency and the Energetic Cost of Proprioception

Actuator Transparency and the Energetic Cost of Proprioception

Empirical validation of a spined sagittal-plane quadrupedal model

Coronal Plane Spine Twisting Composes Shape To Adjust the Energy Landscape for Grounded Reorientation

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