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28 Items

Recent Submissions
Berlin Robust Orientation Estimation Assessment Dataset (BROAD)

Laidig, Daniel (2021-06-11)

Data files and example code for the BROAD benchmark for inertial orientation estimation. For more details, see the following publication: D. Laidig, M. Caruso, A. Cereatti, T. Seel. BROAD -- A Benchmark for Robust Inertial Orientation Estimation. Submitted to Data. A copy of this dataset is also available at https://github.com/dlaidig/broad.

Analysis of the Accuracy of Ten Algorithms for Orientation Estimation Using Inertial and Magnetic Sensing under Optimal Conditions: One Size Does Not Fit All

Caruso, Marco ; Sabatini, Angelo Maria ; Laidig, Daniel ; Seel, Thomas ; Knaflitz, Marco ; Della Croce, Ugo ; Cereatti, Andrea (2021-04-05)

The orientation of a magneto and inertial measurement unit (MIMU) is estimated by means of sensor fusion algorithms (SFAs) thus enabling human motion tracking. However, despite several SFAs implementations proposed over the last decades, there is still a lack of consensus about the best performing SFAs and their accuracy. As suggested by recent literature, the filter parameters play a central r...

Model decomposition of timed event graphs under periodic partial synchronization: application to output reference control

Trunk, Johannes ; Cottenceau, Bertrand ; Hardouin, Laurent ; Raisch, Jörg (2020-05-27)

Timed Event Graphs (TEGs) are a graphical model for decision free and time-invariant Discrete Event Systems (DESs). To express systems with time-variant behaviors, a new form of synchronization, called partial synchronization (PS), has been introduced for TEGs. Unlike exact synchronization, where two transitions t 1 , t 2 can only fire if both transitions are simultaneously enabled, PS of trans...

Refinements of behavioural abstractions for the supervisory control of hybrid systems

Yang, Jung-Min ; Moor, Thomas ; Raisch, Jörg (2020-04-22)

A common approach to controller synthesis for hybrid systems is to first establish a discrete-event abstraction and then to use methods from supervisory control theory to synthesise a controller. In this paper, we consider behavioural abstractions of hybrid systems with a prescribed discrete-event input/output interface. We discuss a family of abstractions based on so called experiments which c...

A Novel IMU Extrinsic Calibration Method for Mass Production Land Vehicles

Rodrigo Marco, Vicent ; Kalkkuhl, Jens ; Raisch, Jörg ; Seel, Thomas (2020-12-22)

Multi-modal sensor fusion has become ubiquitous in the field of vehicle motion estimation. Achieving a consistent sensor fusion in such a set-up demands the precise knowledge of the misalignments between the coordinate systems in which the different information sources are expressed. In ego-motion estimation, even sub-degree misalignment errors lead to serious performance degradation. The prese...

A challenge: Support of standing balance in assistive robotic devices

Lippi, Vittorio ; Mergner, Thomas (2020-07-29)

Neurological patients using a powered lower-body exoskeleton for rehabilitation of standing and walking skills in an upright body pose face the safety challenge of postural instability and fall. Current research, therefore, develops exoskeletons with self-balancing functions. This study suggests basing the exoskeleton’s stabilization of standing posture on a human-derived postural control mecha...

Inertial-Robotic Motion Tracking in End-Effector-Based Rehabilitation Robots

Passon, Arne ; Schauer, Thomas ; Seel, Thomas (2020-11-27)

End-effector-based robotic systems provide easy-to-set-up motion support in rehabilitation of stroke and spinal-cord-injured patients. However, measurement information is obtained only about the motion of the limb segments to which the systems are attached and not about the adjacent limb segments. We demonstrate in one particular experimental setup that this limitation can be overcome by augmen...

Adaptive multichannel FES neuroprosthesis with learning control and automatic gait assessment

Müller, Philipp ; Ama, Antonio J. del ; Moreno, Juan C. ; Schauer, Thomas (2020-02-28)

Background FES (Functional Electrical Stimulation) neuroprostheses have long been a permanent feature in the rehabilitation and gait support of people who had a stroke or have a Spinal Cord Injury (SCI). Over time the well-known foot switch triggered drop foot neuroprosthesis, was extended to a multichannel full-leg support neuroprosthesis enabling improved support and rehabilitation. However,...

Robust Plug-and-Play Joint Axis Estimation Using Inertial Sensors

Olsson, Fredrik ; Kok, Manon ; Seel, Thomas ; Halvorsen, Kjartan (2020-06-22)

Inertial motion capture relies on accurate sensor-to-segment calibration. When two segments are connected by a hinge joint, for example in human knee or finger joints as well as in many robotic limbs, then the joint axis vector must be identified in the intrinsic sensor coordinate systems. Methods for estimating the joint axis using accelerations and angular rates of arbitrary motion have been ...

Inertial Sensors—Applications and Challenges in a Nutshell

Seel, Thomas ; Kok, Manon ; McGinnis, Ryan S. (2020-10-31)

This editorial provides a concise introduction to the methods and applications of inertial sensors. We briefly describe the main characteristics of inertial sensors and highlight the broad range of applications as well as the methodological challenges. Finally, for the reader’s guidance, we give a succinct overview of the papers included in this special issue.

Optimal control of timed event graphs with resource sharing and output-reference update

Schafaschek, Germano ; Hardouin, Laurent ; Raisch, Jörg (2020-07-03)

Timed event graphs (TEGs) are a subclass of timed Petri nets that model synchronization and delay phenomena, but not conflict or choice. We consider a scenario where a number of TEGs share one or several resources and are subject to changes in their output-reference signals. Because of resource sharing, the resulting overall discrete event system is not a TEG. We propose a formal method to dete...

Secondary control in inverter-based microgrids

Krishna, Ajay (2020)

Das Konzept von Microgrids könnte entscheidend zur Bewältigung von Herausforderungen durch die zunehmende Integration erneuerbarer Energiequellen in elektrische Energiesysteme beitragen. Die fluktuierende und dezentrale Einspeisung erneuerbarer Energien führt zu vielen anspruchsvollen und neuen Aufgaben für die Regelung von Microgrids. In der vorliegenden Arbeit werden daher einige wichtige Reg...

Overcoming Bandwidth Limitations in Wireless Sensor Networks by Exploitation of Cyclic Signal Patterns: An Event-triggered Learning Approach

Beuchert, Jonas ; Solowjow, Friedrich ; Trimpe, Sebastian ; Seel, Thomas (2020-01-02)

Wireless sensor networks are used in a wide range of applications, many of which require real-time transmission of the measurements. Bandwidth limitations result in limitations on the sampling frequency and number of sensors. This problem can be addressed by reducing the communication load via data compression and event-based communication approaches. The present paper focuses on the class of a...

On the modeling and control of extended timed event graphs in dioids

Trunk, Johannes (2020)

Various kinds of manufacturing systems can be modeled and analyzed by Timed Event Graphs (TEGs). These TEGs are a particular class of timed Discrete Event Systems (DESs), whose dynamic behavior is characterized only by synchronization and saturation phenomena. A major advantage of TEGs over many other timed DES models is that their earliest behavior can be described by linear equations in some ...

Feedback control of arm movements using Neuro-Muscular Electrical Stimulation (NMES) combined with a lockable, passive exoskeleton for gravity compensation

Klauer, Christian ; Schauer, Thomas ; Reichenfelser, Werner ; Karner, Jakob ; Zwicker, Sven ; Gandolla, Marta ; Ambrosini, Emilia ; Ferrante, Simona ; Hack, Marco ; Jedlitschka, Andreas ; Duschau-Wicke, Alexander ; Gföhler, Margit ; Pedrocchi, Alessandra (2014-09-02)

Within the European project MUNDUS, an assistive framework was developed for the support of arm and hand functions during daily life activities in severely impaired people. This contribution aims at designing a feedback control system for Neuro-Muscular Electrical Stimulation (NMES) to enable reaching functions in people with no residual voluntary control of the arm and shoulder due to high lev...

Modeling the Static Force of a Festo Pneumatic Muscle Actuator: A New Approach and a Comparison to Existing Models

Martens, Mirco ; Boblan, Ivo (2017-11-02)

In this paper, a new approach for modeling the static force characteristic of Festo pneumatic muscle actuators (PMAs) will be presented. The model is physically motivated and therefore gives a deeper understanding of the Festo PMA. After introducing the new model, it will be validated through a comparison to a measured force map of a Festo DMSP-10-250 and a DMSP-20-300, respectively. It will be...

A Novel Framework for a Systematic Integration of Pneumatic-Muscle-Actuator-Driven Joints into Robotic Systems Via a Torque Control Interface

Martens, Mirco ; Seel, Thomas ; Zawatzki, Johannes ; Boblan, Ivo (2018-11-28)

In this paper, two different torque control approaches for PMA-driven (PMA = Pneumatic muscle actuator) revolute joints are presented and tested. In previous work controllers for PMA-driven robots are typically customized for the use on a specific robotic system. In contrast, the proposed controllers define a general control interface for every robot that is actuated by PMA-driven joints. It wi...

User-centered practicability analysis of two identification strategies in electrode arrays for FES induced hand motion in early stroke rehabilitation

Salchow-Hömmen, Christina ; Jankowski, Natalie ; Valtin, Markus ; Schönijahn, Laura ; Böttcher, Sebastian ; Dähne, Frank ; Schauer, Thomas (2018-12-29)

Background Surface electrode arrays have become popular in the application of functional electrical stimulation (FES) on the forearm. Arrays consist of multiple, small elements, which can be activated separately or in groups, forming virtual electrodes (VEs). As technology progress yields rising numbers of possible elements, an effective search strategy for suitable VEs in electrode arrays is ...

A Tangible Solution for Hand Motion Tracking in Clinical Applications

Salchow-Hömmen, Christina ; Callies, Leonie ; Laidig, Daniel ; Valtin, Markus ; Schauer, Thomas ; Seel, Thomas (2019-01-08)

Objective real-time assessment of hand motion is crucial in many clinical applications including technically-assisted physical rehabilitation of the upper extremity. We propose an inertial-sensor-based hand motion tracking system and a set of dual-quaternion-based methods for estimation of finger segment orientations and fingertip positions. The proposed system addresses the specific requiremen...

Feedback-controlled functional electrical stimulation to restore upper extremity functions

Klauer, Christian (2019)

This thesis considers Neuro-prosthetic systems using Functional Electrical Stimulation (FES) to restore or support motor functions in neurologically impaired patients. An often encountered difficulty is the precise control of limb motion by adjusting the stimulation intensity. The musculoskeletal systems involving muscle mechanics, limb motion dynamics, and muscle recruitment due to FES and pos...