Surface electromyography (sEMG) sensor is widely used to operate a myoelectric prosthesis and it has been further developed for various applications. In this paper, a multi-channel sEMG knit band sensor is newly suggested to be worn easily by amputee for myoelectric prosthesis. The band sensor was fabricated by knitting the silver-plated conductive yarn for electrodes with the moisture-wicking technical yarn for the comfort, ultimately, to record eight-channel sEMG signals simultaneously. Several experiments were conducted to verify the performance of knit band sensor. The normalized correlation between the developed knitted electrodes and the disposable (Ag/AgCl) electrodes is very high (0.95) at the same muscular area. The average signal-to-noise ratio value of the knitted electrodes (17.91 dB) was higher than that of the disposable electrodes (13.30 dB). For the performances of motion classification, overall classification accuracy of the knitted electrodes (93.2%) was higher than that of the disposable (87.9%). These experimental results have supported that the developed knit band sensor was as effective as the disposable electrodes.

The paper proposes an EMG-FMG-based prosthesis using a vibrational feedback method. The control loop for bio-feedback consists of a feed-forward loop for controlling the prosthetic hand and a sensory feedback loop for delivering the sense of vibration according to the distance with an object. In addition, the motion of the prosthetic hand using the EMG-FMG knit band sensor as an input device is generated via a decision tree algorithm, the distance is measured using a capacitive knit data glove, and the vibrational feedback using a PVDF piezoelectric actuator is provided. The control loop for bio-feedback was verified experimentally. First, the performance of the sensors and control methods was analyzed, and the results of EMG-FMG motion recognition and vibrational feedback were verified. Second, the experiment was conducted on ten subjects who wore prosthesis to which the bio-feedback method was applied. Thanks to the control loops for bio-feedback, the grasping time with blindfolded was reduced by 2.92 seconds and the number of failures decreased by 1.04 times. As a result, it was confirmed that the control loop for bio-feedback could improve the performance of the prosthesis.

Variable impedance control has been required to perform a variety of interactive tasks in contact with environments. In some cases, the time-varying stiffness matrix of the impedance model can be used to achieve high performance for uneven contact tasks. In the paper, two sufficient conditions are proposed to ensure the input-to-state stability (ISS) irrespective of time-varying stiffness. Furthermore, the update rule of the stiffness is also suggested in such a way that the asymptotic stability is guaranteed under certain region conditions. Even when the update rule is not applied, the ISS is at least assured. In other words, the error is always bounded only if the external force/torque is bounded. In detail, two sufficient conditions offer the lower bound of stiffness and the upper bound of its time derivative. Simulation results show that the ISS of variable impedance control is achieved if the proposed sufficient conditions are satisfied. Also, we can confirm the asymptotic behavior in the simulation when the stiffness is updated according to the given rule.

This paper presents a technique for parametric modeling of biomedical signals, which is based on the autoregressive moving-average (ARMA) model. the ARMA model proposed in this paper is derived from the equivalent AR (EAR) model contributed to the equivalent relation between an infinite-order AR model and a finite-order ARMA model. And then, the recursive method for determining the finite-order parameters of ARMA model from the EAR model is proposed.

Our purpose was to compare the contributions of these two systems to assess PIP joint extension in fresh cadaver models. Nine middle fingers of fresh cadavers were used. The PIP joint angle was measured while an extension load was applied on the extensor tendons. Specimens on which extension load was applied on the extrinsic extensors were classified as the extrinsic group, and those on which extension load was applied on the intrinsic extensors were classified as the intrinsic group. Linear regression analyses were performed to obtain regression equation and the extension load‐PIP joint angle curve. The mean of slope of the curve was compared between the two groups using paired t‐test. The same experiments were done for the metacarpophalangeal (MP) joint in 0° and 60° flexion to evaluate the effect of MP joint flexion on PIP joint extension. The mean slope of the extension load‐PIP joint angle curve of the extrinsic group was significantly greater than that of the intrinsic group. With the MP joint in 0° flexion, the mean slope of the extrinsic and intrinsic groups was ‐0.148 and ‐0.117, respectively (greater absolute value means greater slope, p = 0.01). With the MP joint in 60° flexion, the mean slopes were ‐0.147 and ‐0.104, respectively (p = 0.015). The contribution of the intrinsic extensor for PIP joint extension shows decreasing trends with MP joint flexion. The extrinsic extensors have greater contribution for PIP joint extension compared with the intrinsic extensors.