Walking With Confidence: Safety Regulation for Full Order Biped Models

Smit-Anseeuw, Nils; Remy, C. David; Vasudevan, Ram

doi:10.1109/lra.2019.2931225

Cited by 9 publications

(3 citation statements)

References 29 publications

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“…In Our approach can also be used in real time to inform controller design for wearable robotic devices because it provides time-varying boundaries on the region inside which an individual is stable. Determining the state at which a robotic system is unable to recover from a perturbation is key to designing dynamically stable controllers [49][50][51]. If a prosthetic device or exoskeleton detects that its user has exited the Stability Basin and become unstable, it can adapt its control scheme to aid in recovery.…”

Section: Discussionmentioning

confidence: 99%

Characterizing the limits of human stability during motion: perturbative experiment validates a model-based approach for the Sit-to-Stand task

Holmes

Danforth

et al. 2020

R. Soc. open sci.

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Falls affect a growing number of the population each year. Clinical methods to identify those at greatest risk for falls usually evaluate individuals while they perform specific motions such as balancing or Sit-to-Stand (STS). Unfortunately these techniques have been shown to have poor predictive power and are unable to identify the magnitude, direction, and timing of perturbations that can cause an individual to lose stability during motion. To address this limitation, the recently proposed Stability Basin (SB) aims to characterize the set of perturbations that will cause an individual to fall under a specific motor control strategy. The SB is defined as the set of configurations that do not lead to failure for an individual under their chosen control strategy. This paper presents a novel method to compute the SB and the first experimental validation of the SB with an 11-person perturbative STS experiment involving forwards or backwards pulls from a motor-driven cable. The individually-constructed SBs are used to identify when a trial fails, i.e., when an individual must switch control strategies (indicated by a step or sit) to recover from a perturbation. The constructed SBs correctly predict the outcome of trials where failure was observed with over 90% accuracy, and correctly predict the outcome of successful trials with over 95% accuracy. The SB was compared to three other methods and was found to estimate the stable region with over 45% more accuracy in all cases. This study demonstrates that SBs offer a novel model-based approach for quantifying stability during motion, which could be used in physical therapy for individuals at risk of falling.

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Section: Discussionmentioning

confidence: 99%

Characterizing the limits of human stability during motion: perturbative experiment validates a model-based approach for the Sit-to-Stand task

Holmes

Danforth

et al. 2020

R. Soc. open sci.

Self Cite

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“…Risk assessment is a crucial tool that must be used to enhance safety for both humans and robot systems. from literature review [22][23][24][25][26][27] discussed some history of operators and robots and how industrial robots have been evolved, differences between collaborative and non-collaborative robot cell safeguarding, voluntary industry consensus standards, and the risk assessment. Risk assessment should include quantitative head injury index for service robots as mechanical risk and incidents such as robot throws or drops and trapping and crushing are more to happen with such robots.…”

Section: Literature Reviewmentioning

confidence: 99%

Human-Robot Interaction and Collaboration (HRI-C) Utilizing Top-View RGB-D Camera System

Tashtoush¹,

Garcia²,

Landa³

et al. 2021

IJACSA

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In this study, a smart and affordable system that utilizes an RGB-D camera to measure the exact position of an operator with respect to an adjacent robotic manipulator was developed. This developed technology was implemented in a simulated human operation in an automated manufacturing robot to achieve two goals; enhancing the safety measures around the robot by adding an affordable smart system for human detection and robot control and developing a system that will allow the between the human-robot collaboration to finish a predefined task. The system utilized an Xbox Kinect V2 sensor/camera and Scorbot ER-V Plus to model and mimics the selected applications. To achieve these goals, a geometric model for the Scorbot and Xbox Kinect V2 was developed, a robotics joint calibration was applied, an algorithm of background segmentation was utilized to detect the operator and a dynamic binary mask for the robot was implemented, and the efficiency of both systems based on the response time and localization error was analyzed. The first application of the Add-on Safety Device aims to monitor the working-space and control the robot to avoid any collisions when an operator enters or gets closer. This application will reduced and remove physical barriers around the robots, expand the physical work area, reduce the proximity limitations, and enhance the human-robots interaction (HRI) in an industrial environment while sustaining a low cost. The system was able to respond to human intrusion to prevent any collision within 500 ms on average, and it was found that the system's bottleneck was PC and robot inter-communication speed. The second application was developing a successful collaborative scenario between a robot and a human operator, where a robot will deposit an object on the operator's hand, mimicking a real-life human-robot collaboration (HRC) tasks. The system was able to detect the operator's hand and it's location then command the robot to place an object on the hand, the system was able to place the object within a mean error of 2.4 cm, and the limitation of this system was the internal variables and data transmitting speed between the robot controller and main computer. These results are encouraging and ongoing work aims to experiment with different operations and implement gesture detection in real-time collaboration tasks while keeping the human operator safe and predicting their behavior.

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“…In the controls, robotics, and navigation communities, it is often critical to place strict guarantees on the behavior of a dynamical system. Example applications of such guarantees include collision avoidance [1]- [4], fault detection [5], [6], and control invariance [4], [7], [8]. A common strategy for enforcing such guarantees, especially for uncertain dynamical systems, is to compute the system's reachable set of states, then guarantee that this set lies within certain bounds (e.g., for fault detection) or obeys non-intersection constraints (e.g., for collision avoidance).…”

Section: Introductionmentioning

confidence: 99%

Ellipsotopes: Combining Ellipsoids and Zonotopes for Reachability Analysis and Fault Detection

Kousik¹,

Dai²,

Gao

2021

Preprint

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Ellipsoids are a common representation for reachability analysis because they are closed under affine maps and allow conservative approximation of Minkowski sums; this enables one to incorporate uncertainty and linearization error in a dynamical system by exapnding the size of the reachable set. Zonotopes, a type of symmetric, convex polytope, are similarly frequently used due to efficient numerical implementation of affine maps and exact Minkowski sums. Both of these representations also enable efficient, convex collision detection for fault detection or formal verification tasks, wherein one checks if the reachable set of a system collides (i.e., intersects) with an unsafe set. However, both representations often result in conservative representations for reachable sets of arbitrary systems, and neither is closed under intersection. Recently, constrained zonotopes and constrained polynomial zonotopes have been shown to overcome some of these conservatism challenges, and are closed under intersection. However, constrained zonotopes can not represent shapes with smooth boundaries such as ellipsoids, and constrained polynomial zonotopes can require solving a non-convex program for collision checking (i.e., fault detection). This paper introduces ellipsotopes, a set representation that is closed under affine maps, Minkowski sums, and intersections. Ellipsotopes combine the advantages of ellipsoids and zonotopes, and enable convex collision checking at the expense of more conservative reachable sets than constrained polynomial zonotopes. The utility of this representation is demonstrated on several examples.

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Walking With Confidence: Safety Regulation for Full Order Biped Models

Cited by 9 publications

References 29 publications

Characterizing the limits of human stability during motion: perturbative experiment validates a model-based approach for the Sit-to-Stand task

Characterizing the limits of human stability during motion: perturbative experiment validates a model-based approach for the Sit-to-Stand task

Human-Robot Interaction and Collaboration (HRI-C) Utilizing Top-View RGB-D Camera System

Ellipsotopes: Combining Ellipsoids and Zonotopes for Reachability Analysis and Fault Detection

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