We propose a systematic modeling of the nonholonomic mobile manipulators built from a robotic arm mounted on a wheeled mobile platform. We use the models derived to generalize the standard definition of manipulability to the case of mobile manipulators. The effects of mounting a robotic arm on a nonholonomic platform are shown through the analysis of the manipulability thus defined. Several applications are evoked, particularly applications to control. The optimization of criteria inherited from manipulability considerations are given to generate the controls of our system when its end effector motion is imposed.

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The aim of this study was to investigate whether cognitive performance was a valid marker of overreaching. 10 well-trained male endurance athletes increased their training load by 100% for 2 weeks. They performed a maximal graded test, a constant speed test, a reaction time task and a computerized version of the Stroop color word-test before and after this overload period. Regarding performance results, five participants were considered as overreached and the five remaining were considered as well-trained. We found no significant differences between groups in performing the Stroop test. Noteworthy, we found a small increase in response time in the more complex condition in overreached athletes (1 188+/-261 to 1 297+/-231 ms, effect size=0.44), while it decreased moderately in the well-trained athletes (1 066+/-175 to 963+/-171 ms, effect size=-0.59). Furthermore, we found an interaction between time and group on initiation time of the reaction time task, since it increased in overreached athletes after the overload period (246+/-24 to 264+/-26 ms, p<0.05), while it remained unchanged in well-trained participants. Participants made very few anticipation errors, whatever the group or the period (error rate <2%).We concluded that an unaccustomed increase in training volume which is accompanied by a decrement in physical performance induces a deterioration of some executive functions.

Attentional control dysfunction is different in NA and AD: NA affects suppressing attention, switching attention for unpredictable but not predictable events, and preparing attention for unpredictable events, whereas AD affects setting, suppressing, switching, and preparing attention with less specificity.