Control Scheme and Uncertainty Considerations for Dynamic Balancing of Passive-Ankled Bipeds and Full Humanoids

Kim, D.; Jorgensen, Steven Jens; Hwang, Hochul; Sentis, Luis

doi:10.1109/humanoids.2018.8624915

Cited by 10 publications

(3 citation statements)

References 14 publications

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“…Exoskeletons with feet can topple over, and we use an inequality-constrained floating base model Koolen et al (2016) ; Kim et al (2016 , 2018) ; Mungai and Grizzle (2020) to keeping its feet flat on the ground. These inequality constraints act on the base–ground reaction forces, f r defined by the combination of the floating-base exoskeleton and a contact constraint (notation as in Table 4 ):

…”

Section: Weighted 1-norm Shared-body Controlmentioning

confidence: 99%

Formulating and Deploying Strength Amplification Controllers for Lower-Body Walking Exoskeletons

et al. 2021

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Augmenting the physical strength of a human operator during unpredictable human-directed (volitional) movements is a relevant capability for several proposed exoskeleton applications, including mobility augmentation, manual material handling, and tool operation. Unlike controllers and augmentation systems designed for repetitive tasks (e.g., walking), we approach physical strength augmentation by a task-agnostic method of force amplification—using force/torque sensors at the human–machine interface to estimate the human task force, and then amplifying it with the exoskeleton. We deploy an amplification controller that is integrated into a complete whole-body control framework for controlling exoskeletons that includes human-led foot transitions, inequality constraints, and a computationally efficient prioritization. A powered lower-body exoskeleton is used to demonstrate behavior of the control framework in a lab environment. This exoskeleton can assist the operator in lifting an unknown backpack payload while remaining fully backdrivable.

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…”

Section: Weighted 1-norm Shared-body Controlmentioning

confidence: 99%

Formulating and Deploying Strength Amplification Controllers for Lower-Body Walking Exoskeletons

et al. 2021

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“…Existing locomotion schemes in limbed robots for example are performed with quasi-static, capture-point, divergent component of motion (DCM) [10], time-velocityreversal (TVR) [22], or centroidal-momentum based planners [23]. These high-level planners output CoM trajectories (and sometimes momentum trajectories) for a given sequence of contact modes.…”

Section: B Defining the Locomotion Constraint Manifoldmentioning

confidence: 99%

Finding Locomanipulation Plans Quickly in the Locomotion Constrained Manifold

Jorgensen¹,

Vedantam²,

Gupta³

et al. 2019

Preprint

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We present a method that finds locomanipulation plans that perform simultaneous locomotion and manipulation of objects for a desired end-effector trajectory. Key to our approach is to consider a generic locomotion constraint manifold that defines the locomotion scheme of the robot and then using this constraint manifold to search for admissible manipulation trajectories. The problem is formulated as a weighted-A* graph search whose planner output is a sequence of contact transitions and a path progression trajectory to construct the whole-body kinodynamic locomanipulation plan. We also provide a method for computing, visualizing and learning the locomanipulability region, which is used to efficiently evaluate the edge transition feasibility during the graph search. Experiments are performed on the NASA Valkyrie robot platform that utilizes a dynamic locomotion approach, called the divergent-component-of-motion (DCM), on two example locomanipulation scenarios.

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“…The weight of the robot is 23.5kg. We deliberately install 4 heavy calves on the robot, so that the mass ratio between the legs and the torso is about 40%, which is not negligible according to [23]. The results show that, with the proposed WBC scheme, the robot can achieve robust locomotion with external disturbances.…”

Section: Introductionmentioning

confidence: 99%

Whole-Body Control with Motion/Force Transmissibility for Parallel-Legged Robot

Wang¹,

Han²,

Ju³

et al. 2021

Preprint

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Whole-body control (WBC) has been applied to the locomotion of legged robots. However, current WBC methods have not considered the intrinsic features of parallel mechanisms, especially motion/force transmissibility (MFT). In this work, we propose an MFT-enhanced WBC scheme. Introducing MFT into a WBC is challenging due to the nonlinear relationship between MFT indices and the robot configuration. To overcome this challenge, we establish the MFT preferable space of the robot and formulate it as a polyhedron in the joint space at the acceleration level. Then, the WBC employs the polyhedron as a soft constraint. As a result, the robot possesses high-speed and high-acceleration capabilities by satisfying this constraint as well as staying away from its singularity. In contrast with the WBC without considering MFT, our proposed scheme is more robust to external disturbances, e.g., push recovery and uneven terrain locomotion. simulations and experiments on a parallel-legged bipedal robot are provided to demonstrate the performance and robustness of the proposed method.

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Control Scheme and Uncertainty Considerations for Dynamic Balancing of Passive-Ankled Bipeds and Full Humanoids

Cited by 10 publications

References 14 publications

Formulating and Deploying Strength Amplification Controllers for Lower-Body Walking Exoskeletons

Formulating and Deploying Strength Amplification Controllers for Lower-Body Walking Exoskeletons

Finding Locomanipulation Plans Quickly in the Locomotion Constrained Manifold

Whole-Body Control with Motion/Force Transmissibility for Parallel-Legged Robot

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