Stochastic estimation of human arm impedance under nonlinear friction in robot joints: A model study

Chang, Pyung Hun; Kang, Sang Hoon

doi:10.1016/j.jneumeth.2010.02.021

Cited by 19 publications

(45 citation statements)

References 37 publications

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“…Pivoting stiffness was quantified using a non-parametric system identification method based on the relationships between the perturbed torque, measured torque, and measured angle (9, 23). Briefly, pivoting stiffness frequency response function (FRF) was determined using Welch’s periodogram method to estimate the power spectral density of the applied 2Hz perturbed torque, measured pivoting torque, and measured pivoting angle (4, 9, 23). Then, leg pivoting stiffness was estimated as the magnitude of the pivoting stiffness FRF at 2Hz (4, 9, 23).…”

Section: Methodsmentioning

confidence: 99%

“…Briefly, pivoting stiffness frequency response function (FRF) was determined using Welch’s periodogram method to estimate the power spectral density of the applied 2Hz perturbed torque, measured pivoting torque, and measured pivoting angle (4, 9, 23). Then, leg pivoting stiffness was estimated as the magnitude of the pivoting stiffness FRF at 2Hz (4, 9, 23). The reliability of leg pivoting stiffness estimation was validated based on coherence of the perturbed torque and the measured angle (close to 1) and coherence of the perturbed torque and the measured torque (close to 1) with low phase angle (close to 0°) of the FRF at 2Hz (4, 9, 23).…”

Section: Methodsmentioning

confidence: 99%

“…Then, leg pivoting stiffness was estimated as the magnitude of the pivoting stiffness FRF at 2Hz (4, 9, 23). The reliability of leg pivoting stiffness estimation was validated based on coherence of the perturbed torque and the measured angle (close to 1) and coherence of the perturbed torque and the measured torque (close to 1) with low phase angle (close to 0°) of the FRF at 2Hz (4, 9, 23). Maximum internal and external pivoting angles across all the stepping cycles were also computed per each task from each evaluation at each person.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Pivoting Neuromuscular Training on Pivoting Control and Proprioception

Lee

Ren

Chang

et al. 2014

Medicine &Amp; Science in Sports &Amp; Exercise

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Purpose Pivoting neuromuscular control and proprioceptive acuity may play an important role in ACL injuries. The goal of this study was to investigate whether pivoting neuromuscular training on an offaxis elliptical trainer (POINT) could improve pivoting neuromuscular control, proprioceptive acuity, and functional performance. Methods Among 41 subjects, 21 subjects participated in 18 sessions of POINT (3 sessions/week for 6 weeks), and 20 subjects served as controls who did their regular workout. Both groups received pre-, mid-, and post-intervention evaluations. Propensity score analysis with multivariable regression adjustment was used to investigate the effect of training on pivoting neuromuscular control (pivoting instability, leg pivoting stiffness, maximum internal and external pivoting angles), proprioceptive acuity, and functional performance in both groups. Results Compared to the control group, the training group significantly improved pivoting neuromuscular control as reduced pivoting instability, reduced maximum internal and external pivoting angles, increased leg pivoting stiffness, and decreased entropy of time to peak EMG in the gluteus maximus and lateral gastrocnemius under pivoting perturbations. Furthermore, the training group enhanced weight-bearing proprioceptive acuity and improved the single leg hop distance. Conclusion Improvement of pivoting neuromuscular control in functional weight-bearing activities and task performances following POINT may help develop lower limb injury prevention and rehabilitation methods to reduce ACL and other musculoskeletal injuries associated with pivoting sports.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Effects of Pivoting Neuromuscular Training on Pivoting Control and Proprioception

Lee

Ren

Chang

et al. 2014

Medicine &Amp; Science in Sports &Amp; Exercise

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“…In terms of motor control, the systematic pattern was found to be affected by wrist and forearm biomechanics, which can be quantified by its coupled dynamic properties (i.e., multi-DOF impedance) [1][2][3][4][5], [7], [14][15][16][17]. The multi-DOF impedance includes limb inertia, damping, and stiffness [1][2][3], [14][15][16][17].…”

mentioning

confidence: 99%

“…The multi-DOF impedance includes limb inertia, damping, and stiffness [1][2][3], [14][15][16][17]. Moreover, the systematic pattern in the wrist 2 DOF (FE and RUD) may be affected by multi-DOF anisotropic stiffness [5], [7] (with nonzero cross-coupled stiffness between DOFs [7], [9], [13], [15], [18]), provided that the 2 DOF impedance can be described as a linear 2 nd order dynamic having values assumed (but not measured except for stiffness) as in [5], [7].…”

mentioning

confidence: 99%

In Vivo Estimation of Human Forearm and Wrist Dynamic Properties

Park

Chang

Kang

2017

IEEE Trans. Neural Syst. Rehabil. Eng.

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It is important to estimate the 3 degree-of-freedom (DOF) impedance of human forearm and wrist (i.e., forearm prono-supination, and wrist flexion-extension and radial-ulnar deviation) in motor control and in the diagnosis of altered mechanical resistance following stroke. There is, however, a lack of methods to characterize 3 DOF impedance. Thus, we developed a reliable and accurate impedance estimation method, the distal internal model based impedance control (dIMBIC)-based method, to characterize the 3 DOF impedance, including cross-coupled terms between DOFs, for the first time. Its accuracy and reliability were experimentally validated using a robot with substantial nonlinear joint friction. The 3 DOF human forearm and wrist impedance of eight healthy subjects was reliably characterized, and its linear behavior was verified. Thus, the dIMBIC-based method can provide us with 3 DOF forearm and wrist impedance regardless of nonlinear robot joint friction. It is expected that, with the proposed method, the 3 DOF impedance estimation can promote motor control studies and complement the diagnosis of altered wrist and forearm resistance post-stroke by providing objective impedance estimates, including cross-coupled terms.

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Teleimpedance Based Assistive Control for a Compliant Knee Exoskeleton

Ajoudani¹

2015

Transferring Human Impedance Regulation Skills to Robots

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This paper presents a tele-impedance based assistive control scheme for a knee exoskeleton device. The proposed controller captures the user's intent to generate task-related assistive torques by means of the exoskeleton in different phases of the subject's normal activity. To do so, a detailed musculoskeletal model of the human knee is developed and experimentally calibrated to best match the users kinematic and dynamic behavior. Three dominant antagonistic muscle pairs are used in our model, in which electromyography (EMG) signals are acquired, processed and used for the estimation of the knee joint torque, trajectory and the stiffness trend, in real time. The estimated stiffness trend is then scaled and mapped to a task-related stiffness interval to agree with the desired degree of assistance. The desired stiffness and equilibrium trajectories are then tracked by the exoskeletons impedance controller. As a consequence, while minimum muscular activity corresponds to low stiffness, i.e. highly transparent motion, higher co-contractions result in a stiffer joint and a greater level of assistance. To evaluate the robustness of the proposed technique, a study of the dynamics of the human-exoskeleton system is conducted, while the stability in the steady state and transient condition is investigated. In addition, experimental results of standing-up and sitting-down tasks are demonstrated to further investigate the capabilities of the controller. The results indicate that the compliant knee exoskeleton, incorporating the proposed tele-impedance controller, can effectively generate assistive actions that are volitionally and intuitively controlled by the user's muscle activity.

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Stochastic estimation of human arm impedance under nonlinear friction in robot joints: A model study

Cited by 19 publications

References 37 publications

Effects of Pivoting Neuromuscular Training on Pivoting Control and Proprioception

Effects of Pivoting Neuromuscular Training on Pivoting Control and Proprioception

In Vivo Estimation of Human Forearm and Wrist Dynamic Properties

Teleimpedance Based Assistive Control for a Compliant Knee Exoskeleton

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