Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    PowerGrasp: Development Aspects for Arm Support Systems
    ( 2022)
    Goppold, J.-P.
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    Kuschan, J.
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    Schmidt, H.
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    Krüger, J.
    Exoskeletons can support workers on physically demanding tasks, but in industry they lack of acceptance. This contribution gives an insight into design aspects for upper body exoskeletons, especially how active exoskeletons for industrial applications differ from military and medical use-cases. To overcome typical rigid exoskeleton problems, we suggest the use of modular soft-exosuit support systems and therefore checked different types of soft actuation principles for their eligibility for the use on upper body joints. Most promising approach is using two-layered actuators sting of robust fabric with embedded rubber tubes as pressure chambers. By inflating the tubes, it is possible to vary the stiffness of the chambers, which can be effectively used to generate assisting forces and moments at human joints (shoulder, elbow, wrist, finger).
  • Publication
    Let's do this together: Bi-Manu-Interact, a novel device for studying human haptic interactive behavior
    ( 2017)
    Ivanova, E.
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    Krause, A.
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    Schälicke, M.
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    Schellhardt, F.
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    Jankowski, N.
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    Achner, J.
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    Schmidt, H.
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    Joebges, M.
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    Krüger, J.
    Our area of interest is robotic-based rehabilitation after stroke, and our goal is to help patients achieve optimal motor learning during high-intensity repetitive movement training through the assistance of robots. It is important, that the robotic assistance is adapted to the patients' abilities, thereby ensuring that the device is only supporting the patient as necessary ('assist-as-needed'). We hypothesize that natural and learning-effective human-machine interaction can be achieved by programming the robot's control, so that it emulates how a physiotherapist adaptively supports the patients' limb movement during stroke rehabilitation. This paper introduces the design of a novel interactive device Bi-Manu-Interact. This device is suited to be used as an experimental setup for the investigation of haptic human-human interaction and for collecting data to model therapists' haptic behavior. In this paper, we present mechanical and sensory specifications as well as task s visualizations for future investigations. Results of a pilot clinical evaluation of the Bi-Manu-Interact with nine stroke patients are also presented in this work.
  • Publication
    Design and concept of a haptic robotic telerehabilitation system for upper limb movement training after stroke
    ( 2015)
    Ivanova, E.
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    Krüger, J.
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    Steingräber, R.
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    Schmid, S.
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    Schmidt, H.
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    Hesse, S.
    Robotic therapy devices have been an important part of clinical neurological rehabilitation for several years. Until now such devices are only available for patients receiving therapy inside rehabilitation hospitals. Since patients should continue rehabilitation training after hospital discharge at home, intelligent robotic rehab devices could help to achieve this goal. This paper proposes a novel multimodal home therapy concept and robot based system for motor telerehabilitation which is currently being further developed. The system is based on two haptic rehabilitation devices i) the Bi-Manu-Track (BMT) 2times1 DOF robotic haptic rehabilitation device with assist-as-needed control algorithms and ii) an enhanced version of the 3 DOF passive Reha-Slide system. The paper describes the technical system setup as well as user centered design aspects.
  • Publication
    Computerized mirror therapy with augmented reflection technology for stroke rehabilitation: A feasibility study in a rehabilitation center
    ( 2015)
    Hoermann, S.
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    Ferreira dos Santos, L.
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    Morkisch, N.
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    Jettkowski, K.
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    Sillis, M.
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    Cutfield, N.J.
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    Schmidt, H.
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    Hale, L.
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    Krüger, J.
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    Regenbrecht, H.
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    Dohle, C.
    New rehabilitation strategies for post-stroke upper limb rehabilitation employing visual stimulation show promising results. Cost-efficient ways to provide these techniques are still a challenge. Virtual and Augmented Reality Technologies could be suitable for this endeavor. Recent technological advances often are not translated into therapeutic practice and improved outcomes for patients because of a lack of research on their practical usage, coupled with the inexistence of appropriate guidelines and protocols. Here we present a novel and affordable augmented reality system that was developed and evaluated in combination with a validated mirror therapy protocol for upper limb rehabilitation after stroke. We evaluated the components of the therapeutic intervention from both the patients' and the therapists' points of view. In particular, we provide evidence that the combination and application of the Berlin Protocol for Mirror Therapy together with Augmented Reflection Technology is feasible for clinical use. This paves the way to a broader use of technically-supported mirror therapy with the possibility of higher therapy frequencies and enhanced recovery for patients.
  • Publication
    Visualization of virtual reality neurological motor rehabilitation of the upper limb - A systematic review
    ( 2013)
    Santos, L.F. dos
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    Schmidt, H.
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    Krüger, J.
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    Dohle, C.
    Most virtual rehabilitation environments rely on visual feedback. However, little is known on the optimum characteristics of these feedbacks. Here, we present first results of a systematic literature review to assess and compare visual feedback types in virtual reality (VR) based neurological motor rehabilitation of the upper limb. Overall we identified 104 relevant publications. Within these some applied multiple visual feedback types. We found six main visualization groups: Avatar Feedback (N=52), Augmented Reality Feedback (N=16), Abstract Feedback (N=40), Tracking Feedback (N=13), Performance Evaluation Feedback (N=2), and Combined Feedback (N=7). However, there is insufficient evidence for the choice of a specific visual feedback in relation to motor outcome. Thus, further research is necessary.
  • Publication
    Optimal torque adaptation in bimanual assisted rehabilitation
    ( 2012)
    Steingräber, R.
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    Schmidt, H.
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    Krüger, J.
  • Publication
    Robot-assisted motor activation monitored by time-domain optical brain imaging
    ( 2011)
    Steinkellner, O.
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    Wabnitz, H.
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    Schmid, S.
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    Steingräber, R.
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    Schmidt, H.
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    Krüger, J.
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    Macdonald, R.
    Robot-assisted motor rehabilitation proved to be an effective supplement to conventional hand-to-hand therapy in stroke patients. In order to analyze and understand motor learning and performance during rehabilitation it is desirable to develop a monitor to provide objective measures of the corresponding brain activity at the rehabilitation progress. We used a portable time-domain near-infrared reflectometer to monitor the hemodynamic brain response to distal upper extremity activities. Four healthy volunteers performed two different robot-assisted wrist/forearm movements, flexion-extension and pronation-supination in comparison with an unassisted squeeze ball exercise. A special headgear with four optical measurement positions to include parts of the pre- and postcentral gyrus provided a good overlap with the expected activation areas. Data analysis based on variance of time-of-flight distributions of photons through tissue was chosen to provide a suitable representati on of intracerebral signals. In all subjects several of the four detection channels showed a response. In some cases indications were found of differences in localization of the activated areas for the various tasks.
  • Publication
    Effect of different training modes on ground reaction forces during robot assisted floor walking and stair climbing
    ( 2009)
    Hussein, S.
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    Schmidt, H.
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    Hesse, S.
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    Krüger, J.
    The HapticWalker is a robotic walking simulator for neurological gait rehabilitation. The device is based on the end-effector principle, i.e. the patients' feet are fixed on two footplates, his trunk is secured via a suspension harness. The footplates (end-effectors) of the robot guide the feet of the patient on freely programmable trajectories. Currently two different training modes are provided for each foot trajectory on the HapticWalker. Firstly training trajectories based on real motion capture data can be used. Secondly the vertical center of mass (CoM) motion can be incorporated into the foot trajectory. The latter method leaves the absolute position of the CoM constant, while the relative movement between CoM and feet remains the same as in free walking. Thereby the v ertical CoM motion can be actively supported by using a fixed passive suspension, any type of controlled body weight support will then be accomplished via force controlled footplates. To characterize the training on the machine in position controlled mode, muscle activities as well as ground reaction force data of healthy subjects were collected. This article presents preliminary results from the investigation of ground reaction force data of healthy subjects. Therefore data of 10 healthy subjects was used to compare HapticWalker training modes vs. free walking on level ground and upstairs without any assistive devices and the aforementioned two HapticWalker training modes against each other. Amplitude and timing of force peaks during heel strike, foot flat and push off in vertical ground reaction forces were used for the assessment. In spite of a footplate, which does not provide a separate metatarsal joint for relative motion between fore and hind foot, during heel strike and push off the known characteristic peaks at the beginning and the end of the stance phase can be clearly distinguished. Though compared to free walking a slower and premature rise and slower decline of ground reaction for- ces can be seen due to the stiff guidance of the feet in position controlled mode. No significant differences appeared between the two described HapticWalker training modes.
  • Publication
    Adaptive control of an end-effector based electromechanical gait rehabilitation device
    ( 2009)
    Hussein, S.
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    Schmidt, H.
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    Krüger, J.
    In industrialized countries stroke is the major cause for physical disabilities in adults. In various clinical studies gait therapy with the help of the electromechanical Gait Trainer GT-I proved to enhance the rehabilitation outcome for subacute stroke patients. This paper presents control methods that were developed to enable variability during treatment in order to further improve gait therapy with this class of devices. The algorithms suitable for the Gait Trainer GT-I are analyzed in a simulation study. Therefore models which simulate the practicing subjects behaviour were developed. A purely mechanical mass-damper system models the passive subjects behaviour while motor learning models were adopted to simulate patient adaptation different types of footplate gui dance characteristics. Several adaptive approaches have been developed for other rehabilitation devices in the past. In this work two controllers were developed and evaluated. The first features a one dimensional control window along the footplate trajectory within which the patient is only slightly guided. Outside the window a force field draws the subject back to the window. The second algorithm extends the window controller with a human motor learning strategy for to adapt the window size and thereby the assistance provided to the subjects. They were tested in a simulation study with different human behaviour models, the results are presented in this paper.