Low Impedance-Guaranteed Gain-Scheduled GESO for Torque-Controlled VSA With Application of Exoskeleton-Assisted Sit-to-Stand

Liu, Lin; Hong, Zejun; Penzlin, Bernhard; Misgeld, Berno J.E.; Ngo, Chuong; Bergmann, Lukas; Leonhardt, Steffen

doi:10.1109/tmech.2020.3032372

Cited by 18 publications

(13 citation statements)

References 33 publications

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“…The available options to estimate the interactive force-torque are limited [5]. One method is to apply the inverse model of the exoskeleton robot to derive the joint torques [6,7]. However, the parameters of the inverse models vary strongly among individuals, with time, and depending on the task, which makes robust impedance control challenging [8,9].…”

Section: Introductionmentioning

confidence: 99%

A Wearable, Multi-Frequency Device to Measure Muscle Activity Combining Simultaneous Electromyography and Electrical Impedance Myography

Ngo

Muñoz

Lueken

et al. 2022

Sensors

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The detection of muscle contraction and the estimation of muscle force are essential tasks in robot-assisted rehabilitation systems. The most commonly used method to investigate muscle contraction is surface electromyography (EMG), which, however, shows considerable disadvantages in predicting the muscle force, since unpredictable factors may influence the detected force but not necessarily the EMG data. Electrical impedance myography (EIM) investigates the change in electrical impedance during muscle activities and is another promising technique to investigate muscle functions. This paper introduces the design, development, and evaluation of a device that performs EMG and EIM simultaneously for more robust measurement of muscle conditions subject to artifacts. The device is light, wearable, and wireless and has a modular design, in which the EMG, EIM, micro-controller, and communication modules are stacked and interconnected through connectors. As a result, the EIM module measures the bioimpedance between 20 and 200 Ω with an error of less than 5% at 140 SPS. The settling time during the calibration phase of this module is less than 1000 ms. The EMG module captures the spectrum of the EMG signal between 20–150 Hz at 1 kSPS with an SNR of 67 dB. The micro-controller and communication module builds an ARM-Cortex M3 micro-controller which reads and transfers the captured data every 1 ms over RF (868 Mhz) with a baud rate of 500 kbps to a receptor connected to a PC. Preliminary measurements on a volunteer during leg extension, walking, and sit-to-stand showed the potential of the system to investigate muscle function by combining simultaneous EMG and EIM.

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Section: Introductionmentioning

confidence: 99%

A Wearable, Multi-Frequency Device to Measure Muscle Activity Combining Simultaneous Electromyography and Electrical Impedance Myography

Ngo

Muñoz

Lueken

et al. 2022

Sensors

Self Cite

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“…Therefore, closed-loop control can only compromise on rapidity to attain the stability under the condition of minimum stiffness. The changing relationship between force and displacement was fully utilized to reduce the influence of excessive stiffness changes on force loading [ 29 , 30 ]. On the one hand, it can avoid the limitation of low stiffness to the entire system’s performance.…”

Section: Introductionmentioning

confidence: 99%

Study on the Control Method of Knee Joint Human–Exoskeleton Interactive System

Wang

Yang

Ding

et al. 2022

Sensors

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The advantages of exoskeletons based on the Bowden cable include being lightweight and flexible, thus being convenient in assisting humans. However, the performance of an exoskeleton is limited by the structure and human–exoskeleton interaction, which is analyzed from the established mathematical model of the human–exoskeleton system. In order to improve the auxiliary accuracy, corresponding control methods are proposed. The disturbance observer is designed to compensate for disturbances and parameter perturbations in the inner loop. The human–exoskeleton interaction feedforward model is integrated into the admittance control, which overcomes the limitation of the force loading caused by the friction of the Bowden cable and the change in stiffness of the human–exoskeleton interaction. Furthermore, an angle prediction method using the encoder as the signal source is designed to reduce the disturbance of the force loading caused by human motion. Finally, the effectiveness of the design method proposed in this paper is verified through experiments.

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“…In our overview, only the Mindwalker prototype contains serial elastic actuators (SEAs), which introduce a compliant element between the actuator and load to decouple the robot from the load for smoother human-machine interaction [7]. The serial compliance in the mechanical design, furthermore, causes a bandwidth limitation of the system, which has to be compensated by additional design modifications, such as the capability of stiffening the elastic element [9]. However, in rehabilitation robotics, including applications where strong patient activity is not expected, for example, for paraplegics, rigid drives have often been used to date (see Table 1).…”

Section: Introductionmentioning

confidence: 99%

Design and First Operation of an Active Lower Limb Exoskeleton with Parallel Elastic Actuation

Penzlin

Bergmann

et al. 2021

Actuators

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The lower limb exoskeleton investigated in this work actively supports the knee and hip and is intended to provide full motion support during gait. Parallel elastic actuators are integrated into the hip joints to improve the energy efficiency in gait. The prototype was tested in sit-to-stand and gait trials, in which the actuators were cascade-controlled with position trajectories. The compliant actuation of the hip in gait experiments proved to be more efficient; the peak torque was reduced by up to 31% and the RMS power was reduced by up to 36%.

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Low Impedance-Guaranteed Gain-Scheduled GESO for Torque-Controlled VSA With Application of Exoskeleton-Assisted Sit-to-Stand

Cited by 18 publications

References 33 publications

A Wearable, Multi-Frequency Device to Measure Muscle Activity Combining Simultaneous Electromyography and Electrical Impedance Myography

A Wearable, Multi-Frequency Device to Measure Muscle Activity Combining Simultaneous Electromyography and Electrical Impedance Myography

Study on the Control Method of Knee Joint Human–Exoskeleton Interactive System

Design and First Operation of an Active Lower Limb Exoskeleton with Parallel Elastic Actuation

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