Improving simultaneous and proportional control from EMG signals based on a Two-Stage Regression Structure.

A two-stage regression structure is proposed in this paper to improve simultaneous and proportional control based on electromyography (EMG) signals. Instead of considering the conventional approach with a regression model per degree of freedom (DoF), the proposed method applies a regression model per direction of each DoF: the 1st stage detects DoFs and then is used to select the direction models of the 2nd stage. By using linear regression on the data from one healthy experienced participant for 2 DoFs of his wrist, the proposed structure was evaluated offline with cross-evaluation and online with a real-time control of a cursor to hit some targets. The evaluation results showed a clear improvement of the proposed method in terms of accuracy, ability to reach the boundaries, reaction speed, accurate control and reactive control compared to the conventional approach. The potential of this structure also lies in the fact that it can use different regression methods, work for 3 DoFs and more and use the 1st stage knowledge to improve performance of the 2nd stage.

A microcontinuum model for mechanical properties of esophageal tissue: experimental methodology and constitutive analysis.

Accurate material properties of tissues are a key factor for the improvement of medical procedures and treatments. Experimental data are essential in order to formulate and validate a useful constitutive model for predicting the mechanical behavior of tissues in these procedures. This study develops a comprehensive experimental protocol at multiple length scale levels in order to obtain stress-strain curves for esophagus tissue. This paper compares two different models: a conventional, non-linear elastic model, and a microcontinuum model based on fiber rearrangement. Also, a detailed description of the experimental procedure is provided. While the focus was on esophageal tissues, the experimental procedure and microcontinuum are considered widely applicable to other samples of soft tissue.

The effect of tip geometry on the mechanical performance of unused and reprocessed orthopaedic drill bits.

Although reprocessed drill bits have been in clinical use as a cost-saving measure, their performance has not been critically evaluated in comparison with the performance of unused drill bits. The effect of three commonly used reprocessing methods on the geometry and mechanical performance of 2.5 mm orthopaedic drill bits was investigated and compared with that for unused drill bits. Four mechanically significant drill parameters including chisel edge, chisel edge angle, point angle, and lip length of 36 drill bits in four groups were measured and compared. Group A included unused drill bits. Group B included drill bits reprocessed once by one company whereas group C included those reprocessed twice by the same method. Group D included drill bits reprocessed once by another company. For mechanical performance, a test set-up was developed in which the time of travel of the drill bits through layers of cortical and trabecular synthetic bone materials under constant compressive force were measured. The geometrical parameters were found to be significantly altered as a result of the reprocessing methods. A linear relationship was derived to relate the chisel edge to the drill time through cortical and trabecular bones. The mechanical performance of drill bits is correlated largely to the chisel edge length. A larger chisel edge is correlated to a reduced drill time, particularly in the cortical bone.