If You Are Old, Videos Look Slow. The Paradoxical Effect of Age-Related Motor Decline on the Kinematic Interpretation of Visual Scenes

Perception and action are tightly coupled. However, there is still little recognition of how individual motor constraints impact perception in everyday life. Here we asked whether and how the motor slowing that accompanies aging influences the sense of visual speed. Ninety-four participants aged between 18 and 90 judged the natural speed of video clips reproducing real human or physical motion (SoS, Sense-of-Speed adjustment task). They also performed a finger tapping task and a visual search task, which estimated their motor speed and visuospatial attention speed, respectively. Remarkably, aged people judged videos to be too slow (speed underestimation), as compared to younger people: the Point of Subjective Equality (PSE), which estimated the speed bias in the SoS task, was +4% in young adults (<40), +12% in old adults (40–70) and +16% in elders. On average, PSE increased with age at a rate of 0.2% per year, with perceptual precision, adjustment rate, and completion time progressively worsening. Crucially, low motor speed, but not low attentional speed, turned out to be the key predictor of video speed underestimation. These findings suggest the existence of a counterintuitive compensatory coupling between action and perception in judging dynamic scenes, an effect that becomes particularly germane during aging.

Influence Mechanism of Electromechanical Parameters on Transient Dynamics of FWD-EVs: Part I: Co-Modeling of IWM and Vehicle System

In-wheel motor (IWM), as an ideal power source of independent four-wheel drive electric vehicles, has been paid more and more attention due to its high-power density, low starting current, wide speed adjustment range, simple control system and robustness. However, the electromechanical issue is enlarged in both longitudinal and vertical because of in-wheel driven scheme. In this paper, the electromagnetic multi-field characteristic of IWM is investigated based on Fourier series method. The negative vibration coupling on vehicle dynamics is discussed by proposing a conjoint electromechanical FWD-EV model. Results shows that the motor incentive coupled with the vehicle system in multi-degree of freedom, caused the body and wheel resonance in the low speed, meanwhile deteriorated the anti-rollover capability of the IWM-EV in the high speed.

Echo-guided LVAD speed optimization for exercise maximization

Background Continuous-flow left ventricular assist devices (LVAD) are becoming a destination therapy in patients with end-stage left ventricular dysfunction and a competitive method for heart transplantation. Current generation pumps operate with a fixed rotation speed and do not have the automatic speed adjustment capability. However, it was shown that acceleration of the pump speed during stress test increases the maximum exercise tolerance. Purpose The study aimed to evaluate the concept of dynamic pump speed optimization based on the echocardiographic assessment of aortic valve opening (AVO) during the cardiopulmonary exercise test (CPET). Methods Patients with implanted third-generation centrifugal continuous-flow LVAD's with hydrodynamic bearing were prospectively included. Two CPET's were performed after resting speed optimization. The first one with maintained baseline pump speed settings, and the second one with gradually increased speed depending on live echocardiographic imaging. The sequence of tests was random. Results Exercise AVO was apparent in all 22 included patients. The resting pump speed was 2691 RPM and incremented on average by 566 RPM (20%). Pump power and flow raised from 5.6 to 9.8 Watts (p<0.0001) and from 5.8 to 7.3 l/min (p<0.0001), respectively. Peak VO2 increased from 11.1 to 12.8 ml/kg/min (p=0.0003) and maximum workload from 1.1 to 1.2 W/kg (p=0.03). The Borg scale exertion level decreased from 15.2 to 13.5 (p=0.0049). There was a visible trend towards longer exercise time (36s) but no statistical significance was achieved (p=0.1). Conclusion Ultrasonographic AVO analysis is possible during CPET's in patients supported with LVAD. Dynamic echo-guided pump speed adjustment based on the AVO improves exercise tolerance, augments peak VO2 consumption and maximal workload. An automatic speed adjustment in the next generations of LVAD controllers might improve functional capacity and requires further basic, technological and clinical research. FUNDunding Acknowledgement Type of funding sources: Other. Main funding source(s): 1. Cor Aegrum Foundation of Cardiac Surgery Development in Cracow2. Medtronic Poland Sp. z o.o.

Speed control of the asynchronous motor using LabVIEW

This paper was presented a comparative study on the methods of adjusting the speed of a three-phase asynchronous motor with a rotor in a short circuit. For the same structure of the experimental stand used, two programs were created, implemented, and validated in LabVIEW. For the first method, the program in LabVIEW was made with the PI (proportional-integrative) controller and for the second method, the program in LabVIEW was made with the Fuzzy Logic controller. Following the analysis of the resulting graphs, it was found that the speed control system made with the fuzzy logic controller ensures an increase in its performance compared to the speed control system made with the conventional PI type controller. The indicial responses of the adjustment system of the three-phase asynchronous motor speed with PI controller or Fuzzy Logic controller have been determined in real-time by means of the experimental stand. The override of the speed adjustment system is decreased from the value of 26.9% corresponding to the PI controller to the value of 2.3% corresponding to the Fuzzy Logic controller and the duration of the transient time is decreased from the value of 2.2 s related to the PI controller to the value of 0.5 s, related to the Fuzzy Logic controller. By using the Fuzzy Logic controller, the amount of electrical energy required to supply the electric drive system made with a three-phase asynchronous motor will be reduced. This three-phase asynchronous motor speed adjustment algorithm can be implemented for other electric drive systems from different industrial applications.

Subjective Preferences and Discomfort Ratings of Backrest and Seat Pan Adjustments at Various Speeds

Power seats (i.e., electrically adjustable seats that can be designed to move in several ways) have become increasingly common in airplanes, vehicles, and offices. Many studies have investigated the effects of seat attitude parameters, for example, the inclined angles of a backrest, on discomfort during the adjustment process. However, few studies have considered discomfort under different speeds during the adjustment process. In this study, we investigated discomfort with three speeds (i.e., “fast”, “median”, and “slow” corresponding to three durations of 15, 20, and 25 s, respectively) and two adjustments of a power seat, i.e., incline angle adjustment of the backrest and fore-and-aft position adjustment of the seat pan. We also investigated the effects of different physiological parameters on subjects’ discomfort. Twenty-four subjects (12 males and 12 females) completed a questionnaire to indicate their adjustment condition preferences, to rate their overall discomfort during the adjustment processes on a category-ratio scale, and to rate their local body discomfort. The majority of subjects preferred the fast speed adjustment condition and the trend was that a lower backrest adjustment speed increased discomfort during the process. The dominant local discomfort was in the upper and lower back regions during the backrest adjustment, whereas there was no obvious dominant local discomfort during the seat pan adjustment. The physiological parameters also had significant correlations with discomfort in some adjustment movements, for example, the discomfort was negatively correlated with height during the backrest adjustment.

Time Coordination and Collision Avoidance Using Leader-Follower Strategies in Multi-Vehicle Missions

In recent years, the increasing popularity of multi-vehicle missions has been accompanied by a growing interest in the development of control strategies to ensure safety in these scenarios. In this work, we propose a control framework for coordination and collision avoidance in cooperative multi-vehicle missions based on a speed adjustment approach. The overall problem is decoupled in a coordination problem, in order to ensure coordination and inter-vehicle safety among the agents, and a collision-avoidance problem to guarantee the avoidance of non-cooperative moving obstacles. We model the network over which the cooperative vehicles communicate using tools from graph theory, and take communication losses and time delays into account. Finally, through a rigorous Lyapunov analysis, we provide performance bounds and demonstrate the efficacy of the algorithms with numerical and experimental results.

Research on blood oxygen activity in cerebral cortical motor function areas with adjustment intention during gait

BACKGROUND: The study of the neural mechanism of human gait control can provide a theoretical basis for the treatment of walking disorders or the improvement of rehabilitation strategies, and further promote the functional rehabilitation of patients with movement disorders. However, the performance and changes of cerebral cortex activity corresponding to gait adjustment intentions are still not clear. OBJECTIVE: The purpose of this study was to detect the blood oxygen activation characterization of the cerebral cortex motor function area when people have the intention to adjust gait during walking. METHODS: Thirty young volunteers (21 ± 1 years old) performed normal walking, speed increase, speed reduction, step increase, and step reduction, during which oxygenated hemoglobin (HbO), deoxygenated hemoglobin (HbR), and total oxyhemoglobin (HbT) information in the prefrontal cortex (PFC), premotor cortex (PMC), supplementary motor area (SMA) was continuous monitored using near-infrared brain functional imaging. RESULTS: (1) With the intention to adjust gait, the HbO concentration in the SMA increased significantly, while the HbT concentration in the medial-PFC decreased significantly. (2) In the HbO concentration, step reduction is more activated than the step increase in the left-PMC (p= 0.0130); step adjustment is more activated than speed adjustment in the right-PMC (p= 0.0067). In the HbR concentration, the speed reduction is more activated than the speed increase in the left-PFC (p= 0.0103). CONCLUSIONS: When the intention of gait adjustment occurs, the increase of HbO concentration in the SMA indicates the initial stage of gait adjustment will increase the cognitive-locomotor demand of the brain. The left brain area meets the additional nerve needs of speed adjustment. The preliminary findings of this study can lay an important theoretical foundation for the realization of gait control based on fNIRS-BCI technology.