In the nearly six decades since researchers began to explore methods of creating them, exoskeletons have progressed from the stuff of science fiction to nearly commercialized products. While there are still many challenges associated with exoskeleton development that have yet to be perfected, the advances in the field have been enormous. In this paper, we review the history and discuss the state-of-the-art of lower limb exoskeletons and active orthoses. We provide a design overview of hardware, actuation, sensory, and control systems for most of the devices that have been described in the literature, and end with a discussion of the major advances that have been made and hurdles yet to be overcome.

Lower Extremity Exoskeletons and Active Orthoses: Challenges and State-of-the-Art

Wheeled vehicles are often incapable of transporting heavy materials over rough terrain or up staircases. Lower extremity exoskeletons supplement human intelligence with the strength and endurance of a pair of wearable robotic legs that support a payload. This paper summarizes the design and analysis of the Berkeley lower extremity exoskeleton (BLEEX). The anthropomorphically based BLEEX has 7 DOF per leg, four of which are powered by linear hydraulic actuators. The selection of the DOF, critical hardware design aspects, and initial performance measurements of BLEEX are discussed.

Biomechanical design of the Berkeley lower extremity exoskeleton (BLEEX)

Technological advancements have led to the development of numerous wearable robotic devices for the physical assistance and restoration of human locomotion. While many challenges remain with respect to the mechanical design of such devices, it is at least equally challenging and important to develop strategies to control them in concert with the intentions of the user. This work reviews the state-of-the-art techniques for controlling portable active lower limb prosthetic and orthotic (P/O) devices in the context of locomotive activities of daily living (ADL), and considers how these can be interfaced with the user’s sensory-motor control system. This review underscores the practical challenges and opportunities associated with P/O control, which can be used to accelerate future developments in this field. Furthermore, this work provides a classification scheme for the comparison of the various control strategies. As a novel contribution, a general framework for the control of portable gait-assistance devices is proposed. This framework accounts for the physical and informatic interactions between the controller, the user, the environment, and the mechanical device itself. Such a treatment of P/Os – not as independent devices, but as actors within an ecosystem – is suggested to be necessary to structure the next generation of intelligent and multifunctional controllers. Each element of the proposed framework is discussed with respect to the role that it plays in the assistance of locomotion, along with how its states can be sensed as inputs to the controller. The reviewed controllers are shown to fit within different levels of a hierarchical scheme, which loosely resembles the structure and functionality of the nominal human central nervous system (CNS). Active and passive safety mechanisms are considered to be central aspects underlying all of P/O design and control, and are shown to be critical for regulatory approval of such devices for real-world use. The works discussed herein provide evidence that, while we are getting ever closer, significant challenges still exist for the development of controllers for portable powered P/O devices that can seamlessly integrate with the user’s neuromusculoskeletal system and are practical for use in locomotive ADL.

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Control strategies for active lower extremity prosthetics and orthotics: a review

This paper presents a human--machine interface to control exoskeletons that utilizes electrical signals from the muscles of the operator as the main means of information transportation. These signals are recorded with electrodes attached to the skin on top of selected muscles and reflect the activation of the observed muscle. They are evaluated by a sophisticated but simplified biomechanical model of the human body to derive the desired action of the operator. A support action is computed in accordance to the desired action and is executed by the exoskeleton. The biomechanical model fuses results from different biomechanical and biomedical research groups and performs a sensible simplification considering the intended application. Some of the model parameters reflect properties of the individual human operator and his or her current body state. A calibration algorithm for these parameters is presented that relies exclusively on sensors mounted on the exoskeleton. An exoskeleton for knee joint support was designed and constructed to verify the model and to investigate the interaction between operator and machine in experiments with force support during everyday movements.

A Human--Exoskeleton Interface Utilizing Electromyography

Recent development of mechanisms and control strategies for robot-assisted lower limb rehabilitation

In this paper, we present a method to calculate the intended motion of joints in the human body by analysing EMG signals. Those signals are emitted by the muscles attached to the adjoining bones during their activation. With the resulting intended motion, a leg orthosis can be controlled in realtime to support disabled people while walking or climbing stairs and help patients suffering from the effects of a stroke in their rehabilitation efforts. To allow a variety of different motions, a human body model with physical properties is developed and synchronized with data recorded from the pose sensors. Computing the intended motion is performed by converting calibrated EMG signals to muscle forces which animate the model. The algorithm was evaluated with experiments showing the calculated intended motion while climbing one step of a stair. The algorithm and the experimental results are both shown.

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Predicting the intended motion with EMG signals for an exoskeleton orthosis controller

In this paper we present a method to calibrate the surface EMG signal-to-force-relationship online. For this, a simple biomechanical model composed of bones and muscles is used. The calibration is based on an online optimization algorithm where the error between the movement of the human and the movement computed with the biomechanical model is minimized. The proposed method is part of a control system for an exoskeleton robot that should aid the wearer in everyday-life situations like walking, standing up and sitting down. In contrast to existing methods for the calculation of the EMG signal-to-force-relationship, we are not interested in the exact force values of every single muscle, but our model groups some muscles together and uses the EMG signal of one of those muscles as a representative for the group to simplify calculations. The performance of the presented method was investigated on the leg movement in sagittal plane without contact to the environment.

Online calibration of the EMG to force relationship

PreviousNext No AccessSecond International Meeting for Applied Geoscience & EnergyTowards understanding the impact of the evanescent elastodynamic mode coupling in Marchenko equation-based demultiple methodsAuthors: Marcin DukalskiChristian ReinickeKees WapenaarMarcin DukalskiAramco Delft Global Research CenterSearch for more papers by this author, Christian ReinickeAramco Delft Global Research CenterSearch for more papers by this author, and Kees WapenaarDelft University of TechnologySearch for more papers by this authorhttps://doi.org/10.1190/image2022-3745607.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail AbstractMarchenko equation-based methods promise data-driven, true-amplitude internal multiple elimination. The method is exact in 1-D acoustic media, however it needs to be expanded to account for the presence of 2- and 3-D elastodynamic wave-field phenomena, such as compressional (P) to shear (S) mode conversions, total reflections or evanescent waves. Mastering high waveform-fidelity methods such as this, could further advance amplitude vs offset analysis and lead to improved reservoir characterization. This method-expansion may comprise of re-evaluating the underlying assumptions and/or appending the scheme with additional constraints (e.g. minimum phase). To do that, one may need to better understand the construction of the Marchenko equation solutions, the so-called focusing functions, in a mathematically simple and numerically stable fashion. The latter could be a challenge at large angles of incidence where the elastodynamic effects and evanescent waves start playing a dominant role. We demonstrate that the elastodynamic focusing functions are the bridge between the Marchenko equation theory and the transfer matrix formalism. Using the latter, we show how we can try to gain further insights into how time-reversal (correlations) behaves when either of the elastic modes becomes evanescent. We also show how this construction allows us to shed light on into the mathematical properties of elastodynamic inverse transmissions, which takes us a step closer towards understanding the elastodynamic minimum phase reconstruction.Keywords: Internal multiples, Marchenko method, modelingPermalink: https://doi.org/10.1190/image2022-3745607.1FiguresReferencesRelatedDetailsCited byThe propagator and transfer matrix for a 3D inhomogeneous dissipative acoustic medium, expressed in Marchenko focusing functionsKees Wapenaar, Sjoerd de Ridder, Marcin Dukalski, and Christian Reinicke15 August 2022 Second International Meeting for Applied Geoscience & EnergyISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2022 Pages: 3694 publication data© 2022 Published in electronic format with permission by the Society of Exploration Geophysicists and the American Association of Petroleum GeologistsPublisher:Society of Exploration Geophysicists HistoryPublished Online: 15 Aug 2022 CITATION INFORMATION Marcin Dukalski, Christian Reinicke, and Kees Wapenaar, (2022), "Towards understanding the impact of the evanescent elastodynamic mode coupling in Marchenko equation-based demultiple methods," SEG Technical Program Expanded Abstracts : 2827-2831. https://doi.org/10.1190/image2022-3745607.1 Plain-Language Summary KeywordsInternal multiplesMarchenko methodmodelingPDF DownloadLoading ... 

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Towards understanding the impact of the evanescent elastodynamic mode coupling in Marchenko equation-based demultiple methods

Summary Amplitude fidelity is critical for data-driven and wave equation-based methods. In particular, the more advanced methods are often (first) applied on (2-D) sail lines, due to a sparse cross-line sampling, high computational cost or both. Hence, the acquired seismic data needs to be correctly converted from 3-D to 2-D. This is particularly true for the Marchenko method, as it is the only method capable of suppressing internal multiple without the need for adaptive subtraction, but at the cost of the need for a correct global and time- and frequency-dependent scaling. We study the consequences of the conventional (“sqrt-t” and “sqrt-omega”) and advanced 3-D to 2-D conversion on a controlled synthetic dataset. We show that, the impact is particularly significant for the marine setting, where most Marchenko field data applications are expected to be carried out due to high pre-processing requirements. We show that for a simple enough model, the Marchenko method combined with the conventional conversion could under-estimates multiples, whereas the advanced conversion does well. This has important implication for existing and future field data applications. 

Marchenko Multiple Elimination Using Conventional Vs Advanced 3-D To 2-D Conversion on Marine Data

PreviousNext No AccessSecond International Meeting for Applied Geoscience & EnergyThe propagator and transfer matrix for a 3D inhomogeneous dissipative acoustic medium, expressed in Marchenko focusing functionsAuthors: Kees WapenaarSjoerd de RidderMarcin DukalskiChristian ReinickeKees WapenaarDelft University of TechnologySearch for more papers by this author, Sjoerd de RidderUniversity of LeedsSearch for more papers by this author, Marcin DukalskiAramco Delft Global Research CenterSearch for more papers by this author, and Christian ReinickeAramco Delft Global Research CenterSearch for more papers by this authorhttps://doi.org/10.1190/image2022-3735927.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail AbstractStandard Marchenko redatuming and imaging schemes neglect evanescent waves and are based on the assumption that decomposition into downgoing and upgoing waves is possible in the subsurface. Recently we have shown that propagator matrices, which circumvent these assumptions, can be expressed in terms of Marchenko focusing functions. In this paper we generalize the relation between the propagator matrix and the Marchenko focusing functions for a 3D inhomogeneous dissipative medium. Moreover, for the same type of medium we discuss a relation between the transfer matrix and the Marchenko focusing functions.Keywords: Marchenko, multiple, propagatorPermalink: https://doi.org/10.1190/image2022-3735927.1FiguresReferencesRelatedDetails Second International Meeting for Applied Geoscience & EnergyISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2022 Pages: 3694 publication data© 2022 Published in electronic format with permission by the Society of Exploration Geophysicists and the American Association of Petroleum GeologistsPublisher:Society of Exploration Geophysicists HistoryPublished Online: 15 Aug 2022 CITATION INFORMATION Kees Wapenaar, Sjoerd de Ridder, Marcin Dukalski, and Christian Reinicke, (2022), "The propagator and transfer matrix for a 3D inhomogeneous dissipative acoustic medium, expressed in Marchenko focusing functions," SEG Technical Program Expanded Abstracts : 3141-3145. https://doi.org/10.1190/image2022-3735927.1 Plain-Language Summary KeywordsMarchenkomultiplepropagatorPDF DownloadLoading ... 

https://repository.tudelft.nl/islandora/object/uuid%3Af679a158-5ec9-4af3-a168-123a57cc1e6a/datastream/OBJ/download

Christian Reinicke

Papers

Predicting the intended motion with EMG signals for an exoskeleton orthosis controller

Online calibration of the EMG to force relationship

Towards understanding the impact of the evanescent elastodynamic mode coupling in Marchenko equation-based demultiple methods

Marchenko Multiple Elimination Using Conventional Vs Advanced 3-D To 2-D Conversion on Marine Data

The propagator and transfer matrix for a 3D inhomogeneous dissipative acoustic medium, expressed in Marchenko focusing functions