Now showing 1 - 3 of 3
  • Publication
    Muscle activation patterns of healthy subjects during floor walking and stair climbing on an end-effector-based gait rehabilitation robot
    ( 2007)
    Schmidt, H.
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    Volkmar, M.
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    Werner, C.
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    Helmich, I.
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    Piorko, F.
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    Krüger, J.
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    Hesse, S.
    A major criterion for the application of rehabilitation robots in gait therapy is the question to what extent the machine is able to facilitate physiologically correct muscle activation patters in the patients leg muscles in order to achieve an optimal gait training effect The EMG data presented in this paper is based on intermediate results of a study with 8 healthy subjects (5 male, 3 female) to evaluate the end-effector based gait rehabilitation robot HapticWalker in position controlled mode. The study investigated two different walking trajectories (floor, upstairs) at three different cadences (45, 60, 90 steps/min) in three different modes (free walking, HapticWalker with vertical CoM motion, HapticWalker without vertical CoM motion). Results show that muscle EMGs measured from all relevant leg muscles have the same phasic and rhythmic muscle activation patterns on the HapticWalker as with free walking. Even though there are differences in patterns of dedicated muscles, the authors observed reduced amplitudes and slightly delayed activation on the HapticWalker compared to free walking. No differences in EMGs were observed between the two different HapticWalker modes (with vertical CoM motion, cancelled CoM motion), which might eliminate the need for an active trunk suspension system in the latter case. A passive patient lifter would significantly reduce the complexity of the machine construction, all advanced training modes (e.g. dynamic body weight reduction) could then be accomplished via compliant behavior of the freely programmable footplates. Numerous EMG measurements with healthy subjects and non-ambulatory stroke patients were performed on the predecessing electromechanical Gait Trainer GT I and showed that physiologically relevant findings from healthy subjects (e.g. correct phasic muscle activation) can be transferred to a certain extent to stroke patients, but nevertheless studies with stroke patients on the robotic gait trainer HapticWalke. Entnommen aus TEMA
  • Publication
    Gait machines and robots to support motor rehabilitation after stroke
    ( 2007)
    Schmidt, H.
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    Hussein, S.
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    Werner, C.
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    Bernhardt, R.
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    Hesse, S.
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    Krüger, J.
    The group at Klinik Berlin/Charite University Hospital in Berlin, Germany, began studies to promote motor recovery after stroke in the early 1990s. Following the introduction of treadmill training with partial body-weight support, the group designed an electromechanical gait trainer, GT I, based on movable foot plates that relieve therapist effort (e.g., when assisting the movement of the paretic limbs) and intensify patient gait training (GT). Preliminary results of a recent multicenter trial of 155 acute stroke patients showed that the GT I effectively promotes gait ability and competence in activities of daily living. The experimental group received 20 min of GT and 25 min of physiotherapy (PT) and the control group received 45 min of PT every day for 4 weeks. The laboratory's next step was the HapticWalker, a robotic walking simulator with freely programmable foot plates which was designed and built in close collaboration with the Fraunhofer Institute IPK. On this machine patients can, for example, additionally train for stair climbing and perturbations. The foot plates can be operated in full guidance or compliance control modes, thus reducing foot support according to the patient's learning success. Entnommen aus TEMA
  • Publication
    Motion and perturbation generation algorithm for gait rehabilitation robots
    ( 2006)
    Krüger, J.
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    Schmidt, H.
    ;
    Hesse, S.
    Efficient gait rehabilitation requires the patient to practice the whole variety of daily life walking trajectories as early and intensive as possible, because transfer of learning from one gait motion (e.g. walking on even ground) to another (e.g. stepping staircases up/down) proved to be very limited. Therefore gait rehabilitations robots for training of arbitrary walking trajectories need to provide appropriate algorithms for programming and execution of natural walking motions in order to enable proper afferent stimulation of the patients central nervous system. The HapticWalker, a programmable footplate robotic device for gait rehabilitation, is the first device to allow arbitrary foot movements during gait training (e.g. walking on plane floor, upstairs, downstairs, stumbling, sliding). Among the key elements of the HapticWalker robot control software are the motion generation module, which comprises an extended set of motion commands for the simulation of arbitrary natural walking trajectories based on a Cartesian Fourier series interpolation, and the graphical gait motion programming interface, which was specifically designed for operation by non-technical personnel like, for instance, physiotherapists and allows intuitive machine programming based on a minimum set of gait parameters. All motion generation algorithms can be applied for fully guided foot motions, needed in early rehabilitation phases, or in combination with compliance control algorithms, in order to allow haptic patient machine interaction. Automatic motion override adaptation algorithms based on switched low pass filters with a critical damping characteristic were developed for the on-line modulation of the motion override to enable acceleration and deceleration on arbitrary foot trajectories as well as the natural simulation of asynchronous events, i.e. perturbations like for instance stumbling or sliding. The presented algorithms were tested by several healthy subjects and ten stroke and SCI patients in a pilot study, all confirming the natural feeling of walking on the HapticWalker. Entnommen aus TEMA