Automated design of robust discriminant analysis classifier for foot pressure lesions using kinematic data

In the recent years, the use of motion tracking systems for acquisition of functional biomechanical gait data, has received increasing interest due to the richness and accuracy of the measured kinematic information. However, costs frequently restrict the number of subjects employed, and this makes the dimensionality of the collected data far higher than the available samples. This paper applies discriminant analysis algorithms to the classification of patients with different types of foot lesions, in order to establish an association between foot motion and lesion formation. With primary attention to small sample size situations, we compare different types of Bayesian classifiers and evaluate their performance with various dimensionality reduction techniques for feature extraction, as well as search methods for selection of raw kinematic variables. Finally, we propose a novel integrated method which fine-tunes the classifier parameters and selects the most relevant kinematic variables simultaneously. Performance comparisons are using robust resampling techniques such as Bootstrap$632+$and k-fold cross-validation. Results from experimentations with lesion subjects suffering from pathological plantar hyperkeratosis, show that the proposed method can lead to$sim 96$correct classification rates with less than 10% of the original features

How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion?

Locomotor control mechanisms must flexibly adapt to both anticipated and unexpected terrain changes to maintain movement and avoid a fall. Recent studies revealed that ground birds alter movement in advance of overground obstacles, but not treadmill obstacles, suggesting context-dependent shifts in the use of anticipatory control. We hypothesized that differences between overground and treadmill obstacle negotiation relate to differences in visual sensory information, which influence the ability to execute anticipatory manoeuvres. We explored two possible explanations: (1) previous treadmill obstacles may have been visually imperceptible, as they were low contrast to the tread, and (2) treadmill obstacles are visible for a shorter time compared with runway obstacles, limiting time available for visuomotor adjustments. To investigate these factors, we measured electromyographic activity in eight hindlimb muscles of the guinea fowl (Numida meleagris, N=6) during treadmill locomotion at two speeds (0.7 and 1.3 m s−1) and three terrain conditions at each speed: (i) level, (ii) repeated 5 cm low-contrast obstacles (90% contrast, black/white). We hypothesized that anticipatory changes in muscle activity would be higher for (1) high-contrast obstacles and (2) the slower treadmill speed, when obstacle viewing time is longer. We found that treadmill speed significantly influenced obstacle negotiation strategy, but obstacle contrast did not. At the slower speed, we observed earlier and larger anticipatory increases in muscle activity and shifts in kinematic timing. We discuss possible visuomotor explanations for the observed context-dependent use of anticipatory strategies

Temporal adaptations in generic and population-specific quality of life and falls efficacy in men with recent lower-limb amputations

This study examined the longitudinal changes in generic health-related quality of life (QOL), prosthesis-related QOL, falls efficacy, and walking speed in men with lower-limb amputations up to 6 months following discharge from rehabilitation. Seven male unilateral transtibial amputees completed the Medical Outcomes Study 36-Item Short Form Health Survey, the Prosthesis Evaluation Questionnaire, and the Modified Falls Efficacy Scale at 1, 3, and 6 months postdischarge from rehabilitation. Walking speed was also recorded to objectively assess participants’ mobility. Health-related QOL measures displayed increases, resulting in large effect sizes though not reaching statistical significance. Prosthesis-related QOL measures indicated that scales relating to the participants’ prostheses improved and the support of significant others was the most positively scored variable. Walking speed increased by 0.12 m/ s, although it was not significantly related to indices of QOL or falls efficacy. Falls efficacy did not improve significantly during the study period, although it was strongly related to QOL ( p < 0.05). These results provide a novel insight into how QOL and falls efficacy develop in people with lower-limb amputations, alongside changes in mobility, after discharge from rehabilitation. Further improvements in physical health following discharge may be required to elicit subsequent increases in overall QOL and concurrent improvements in falls efficacy

Generation of dynamic motion for anthropomorphic systems under prioritized equality and inequality constraints

In this paper, we propose a solution to compute full-dynamic motions for a humanoid robot, accounting for various kinds of constraints such as dynamic balance or joint limits. As a first step, we propose a unification of task-based control schemes, in inverse kinematics or inverse dynamics. Based on this unification, we generalize the cascade of quadratic programs that were developed for inverse kinematics only. Then, we apply the solution to generate, in simulation, wholebody motions for a humanoid robot in unilateral contact with the ground, while ensuring the dynamic balance on a non horizontal surface