Numerical Estimation of Balanced and Falling States for Constrained Legged Systems

Mummolo, Carlotta; Mangialardi, L.; Kim, Joo H.

doi:10.1007/s00332-016-9353-2

Cited by 20 publications

(22 citation statements)

References 51 publications

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“…However, we are not aware of any such controller. The closest approach to an ideal controller would probably be a whole-body trajectory optimization [28]. However, its large computation time prevents both extensive testing for validation in simulation and application on real systems for balance recovery.…”

Section: A Balance Controllermentioning

confidence: 99%

Zero Step Capturability for Legged Robots in Multicontact

2018

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The ability to anticipate a fall is fundamental for any robot that has to balance. Currently, fast fall-prediction algorithms only exist for simple models, such as the Linear Inverted Pendulum Model (LIPM), whose validity breaks down in multi-contact scenarios (i.e. when contacts are not limited to a flat ground). This paper presents a fast fall-prediction algorithm based on the point-mass model, which remains valid in multicontact scenarios. The key assumption of our algorithm is that, in order to come to a stop without changing its contacts, a robot only needs to accelerate its center of mass in the direction opposite to its velocity. This assumption allows us to predict the fall by means of a convex optimal control problem, which we solve with a fast custom algorithm (less than 11 ms of computation time). We validated the approach through extensive simulations with the humanoid robot HRP-2 in randomly-sampled scenarios. Comparisons with standard LIPM-based methods demonstrate the superiority of our algorithm in predicting the fall of the robot, when controlled with a state-of-the-art balance controller. This work lays the foundations for the solution of the challenging problem of push recovery in multi-contact scenarios.

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Section: A Balance Controllermentioning

confidence: 99%

Zero Step Capturability for Legged Robots in Multicontact

2018

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“…There are different possibilities for the layout of the SY, block and linear stack are the most common layouts [10]. A decision at the strategic level, is the identification of the MHE for the storage and the retrieval of containers from the stack; this evaluation is based on the service time to be ensured and on available resources (SY area, budget, layout adopted, etc.).…”

Section: The Model 21 Process Descriptionmentioning

confidence: 99%

“…Robotized gantry cranes, for moving containers, or biped robots for manipulation tasks, such as lifting and carrying heavy weights, are being adopted mainly for high volume handling. Within these applications, biped robots are required to satisfy not only the power requirements [4], but also advanced balancing and locomotion capabilities [5,6], which are critical for carrying loads [7] and that are required to physically interact with the human-made environment [8,9,10]. There are many elements that affect the efficiency of containers flow.…”

Section: Introductionmentioning

confidence: 99%

A Model for Economic and Environmental Evaluation of Inter-/Intra-Terminal Containers Flows

Facchini¹,

Digiesi²,

Ranieri³

2018

dtetr

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European maritime ports play a fundamental role in maritime transport of containers. One of the more common problem of these ports is related to the berth congestion; in these cases solutions recommended by industry officials is to expand terminal capacity; when this solution is not available the 'Dry port' represents an effective alternative. The dry port is an external area directly connected with one or several seaports by rail and/or road transport. The adoption of a dry port leads to benefits on terminal congestion; depending on the distance of the dry port from the port as well as on the amount of containers stocked in the dry port area, the transport of the containers from port to dry port requires resources. In this paper, a model that allows optimizing the inter-/ intra-terminal flows of the containers is proposed. The model aims at the minimization of costs and environmental impact due to the handling of containers. A full case study concerning a multi-terminal maritime system located in Port of Bari is developed.

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“…There is no commonly applicable and comprehensive framework for the balance stability analysis of robot-assisted locomotion so far. The difficulty arises in part from the traditional challenges in determining balancing vs. falling conditions for general legged systems (Mummolo et al, 2017 ), but also from the modeling complexity of actuator and multibody dynamics of the combined human-exoskeleton system. When addressing the balance stability of robot-assisted gaits, it is essential to establish an accurate model that can describe the dynamics of the combined system representing the human operator wearing the robotic exoskeleton.…”

Section: Introductionmentioning

confidence: 99%

Stability of Mina v2 for Robot-Assisted Balance and Locomotion

et al. 2018

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The assessment of the risk of falling during robot-assisted locomotion is critical for gait control and operator safety, but has not yet been addressed through a systematic and quantitative approach. In this study, the balance stability of Mina v2, a recently developed powered lower-limb robotic exoskeleton, is evaluated using an algorithmic framework based on center of mass (COM)- and joint-space dynamics. The equivalent mechanical model of the combined human-exoskeleton system in the sagittal plane is established and used for balance stability analysis. The properties of the Linear Linkage Actuator, which is custom-designed for Mina v2, are analyzed to obtain mathematical models of torque-velocity limits, and are implemented as constraint functions in the optimization formulation. For given feet configurations of the robotic exoskeleton during flat ground walking, the algorithm evaluates the maximum allowable COM velocity perturbations along the fore-aft directions at each COM position of the system. The resulting velocity extrema form the contact-specific balance stability boundaries (BSBs) of the combined system in the COM state space, which represent the thresholds between balanced and unbalanced states for given contact configurations. The BSBs are obtained for the operation of Mina v2 without crutches, thus quantifying Mina v2's capability of maintaining balance through the support of the leg(s). Stability boundaries in single and double leg supports are used to analyze the robot's stability performance during flat ground walking experiments, and provide design and control implications for future development of crutch-less robotic exoskeletons.

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Numerical Estimation of Balanced and Falling States for Constrained Legged Systems

Cited by 20 publications

References 51 publications

Zero Step Capturability for Legged Robots in Multicontact

Zero Step Capturability for Legged Robots in Multicontact

A Model for Economic and Environmental Evaluation of Inter-/Intra-Terminal Containers Flows

Stability of Mina v2 for Robot-Assisted Balance and Locomotion

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