نتایج جستجو برای: stiffness control
تعداد نتایج: 1366694 فیلتر نتایج به سال:
در این پایان نامه سعی بر این بوده است که با استفاده از یک الگوریتم موثر برای یافتن قطبهای مناسب (مقادیر ویژه ماتریس سیستم)، به صورت کنترل فعال ایده آل، پاسخ های (شتاب و جابجایی) سازه های دوبعدی با جرم متمرکز در طبقات در حالت خطی را در مقابل ارتعاشات جانبی، در حدود مجاز نگاه داشته و سپس با استفاده از میرایی معادل و نیز سختی معادل نیروهای کنترلی ایده آل، سازه های مدل سازی شده، به صورت عملی کنترل ...
BACKGROUND The role of right ventricular (RV) diastolic stiffness in pulmonary arterial hypertension (PAH) is not well established. Therefore, we investigated the presence and possible underlying mechanisms of RV diastolic stiffness in PAH patients. METHODS AND RESULTS Single-beat RV pressure-volume analyses were performed in 21 PAH patients and 7 control subjects to study RV diastolic stiffn...
KEY POINTS The passive stiffness of the calf muscles contributes to standing balance, although the properties of muscle tissue are highly labile. We investigated the effect of sway history upon intrinsic ankle stiffness and demonstrated reductions in stiffness of up to 43% during conditions of increased baseline sway. This sway dependence was most apparent when using low amplitude stiffness-mea...
In this paper a unified contact force control approach for cable-driven parallel robots (CDPR) is proposed. The contact force controller is governed by two control loops: 1) An inner impedance control loop enforcing a dynamical relationship between the internal forces and the end-effector velocities to maintain a desired tension level in the cable system. 2) An outer admittance control loop con...
Robots are now requested to perform more and more complex tasks such as rescue activities in quite practical environments such as rough terrains. It is necessary for robots to have versatile joints that can flexibly adapt to such task environments and realize complex motions. It is desired to develop small and low cost actuators which can flexibly adapt to task environment. Flexibility in robot...
Trunk flexibility may be associated with arterial stiffness in young, middle-aged, and older healthy men after adjusting for blood pressure. This study assessed the effects of 4 weeks of regular static stretching on arterial stiffness in middle-aged men. Sixteen healthy men (43 ± 3 years) were assigned to control or intervention groups (n = 8 each). The control group did not alter their physica...
Atomic force microscopy (AFM) has become a powerful tool for measuring material properties in biology and imposing mechanical boundary conditions on samples from single molecules to cells and tissues. Constant force or constant height can be maintained in an AFM experiment through feedback control of cantilever deflection, known respectively as a 'force clamp' or 'position clamp'. However, stif...
BACKGROUND Despite successful repair, patients with coarctation of the aorta (COA) often show persistent hypertension at rest and/or during exercise. Previous studies indicated that the hypertension is mainly due to abnormalities in the arterial bed and its regulatory systems. We hypothesized that ventricular systolic stiffness also contributes to the hypertensive state in these patients in add...
There is ample evidence that humans are able to control the endpoint impedance of their arms in response to active destabilizing force fields. However, such fields are uncommon in daily life. Here, we examine whether the CNS selectively controls the endpoint impedance of the arm in the absence of active force fields but in the presence of instability arising from task geometry and signal-depend...
Stiffness properties of the musculo-skeletal system can be controlled by regulating muscle activation and neural feedback gain. To understand the regulation of multijoint stiffness, we examined the relationship between human arm joint stiffness and muscle activation during static force control in the horizontal plane by means of surface electromyographic (EMG) studies. Subjects were asked to pr...
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