Scheduling PID Attitude and Position Control Frequencies for Time-Optimal Quadrotor Waypoint Tracking under Unknown External Disturbances

Recently, the use of quadrotors has increased in numerous applications, such as agriculture, rescue, transportation, inspection, and localization. Time-optimal quadrotor waypoint tracking is defined as controlling quadrotors to follow the given waypoints as quickly as possible. Although PID control is widely used for quadrotor control, it is not adaptable to environmental changes, such as various trajectories and dynamic external disturbances. In this work, we discover that adjusting PID control frequencies is necessary for adapting to environmental changes by showing that the optimal control frequencies can be different for different environments. Therefore, we suggest a method to schedule the PID position and attitude control frequencies for time-optimal quadrotor waypoint tracking. The method includes (1) a Control Frequency Agent (CFA) that finds the best control frequencies in various environments, (2) a Quadrotor Future Predictor (QFP) that predicts the next state of a quadrotor, and (3) combining the CFA and QFP for time-optimal quadrotor waypoint tracking under unknown external disturbances. The experimental results prove the effectiveness of the proposed method by showing that it reduces the travel time of a quadrotor for waypoint tracking.

RESEARCH OF FIRE DEVELOPMENT IN MULTI-STORY BUILDINGS IN CITIES OF UKRAINE

The division of urban settlements into appropriate groups by population and area using the methods of cluster analysis. Statistical data characterizing the process of extinguishing fires by emergency rescue formations of cities have been processed. One settlement was selected from each group of cities and data on fires for the period of 2020 were further processed on them. The relationship of the following parameters is established: combustion area; floor of the building; time of fire localization. The obtained static data show that the area of the fire and the localization time increase on average from 3.5 to 6 times. The result of the data analysis makes it possible to calculate the amount of required extinguishing agents when using the method of discrete delivery.

Optimal Search Parameters for A Random Pulsed-Point Source with the Required Accuracy

The questions of creating high-speed algorithms for detecting and localizing point sources having a random distribution and manifesting themselves by generating instantaneous delta pulses at random times are described. The search is carried out by a system including one or more receiving devices, and is performed taking into account the requirements for localization accuracy. It is assumed that all receivers have freely tunable viewing windows. The optimal procedure is one that minimizes (in a statistical sense) the average localization time. It is established that even with relatively low requirements for localization accuracy, the optimal procedure consists of several stages (each such stage ends at the moment of the next pulse registration). In this case, it is possible receiving system to miss some pulses generated by the source during the optimal search. In the work, the optimal search parameters are calculated depending on the number of receiving devices and the required localization accuracy. The possibility of using the results in a multidimensional case is shown.

Time-optimal algorithms focused on the search for random pulsed-point sources

The article describes methods and algorithms related to the analysis of dynamically changing discrete random fields. Time-optimal strategies for the localization of pulsed-point sources having a random spatial distribution and indicating themselves by generating instant delta pulses at random times are proposed. An optimal strategy is a procedure that has a minimum (statistically) average localization time. The search is performed in accordance with the requirements for localization accuracy and is carried out by a system with one or several receiving devices. Along with the predetermined accuracy of localization of a random pulsed-point source, a significant complicating factor of the formulated problem is that the choice of the optimal search procedure is not limited to one-step algorithms that end at the moment of first pulse generation. Moreover, the article shows that even with relatively low requirements for localization accuracy, the time-optimal procedure consists of several steps, and the transition from one step to another occurs at the time of registration of the next pulse by the receiving system. In this case, the situation is acceptable when during the process of optimal search some of the generated pulses are not fixed by the receiving system. The parameters of the optimal search depending on the number of receiving devices and the required accuracy of localization are calculated and described in the paper.

Microtubule-directed transport of purine metabolons drives their cytosolic transit to mitochondria

To meet their purine demand, cells activate the de novo purine biosynthetic pathway and transiently cluster the pathway enzymes into metabolons called purinosomes. Recently, we have shown that purinosomes were spatially colocalized with mitochondria and microtubules, yet it remained unclear as to what drives these associations and whether a relationship between them exist. Here, we employed superresolution imaging methods to describe purinosome transit in the context of subcellular localization. Time-resolved imaging of purinosomes showed that these assemblies exhibit directed motion as they move along a microtubule toward mitochondria, where upon colocalization, a change in purinosome motion was observed. A majority of purinosomes colocalized with mitochondria were also deemed colocalized with microtubules. Nocodazole-dependent microtubule depolymerization resulted in a loss in the purinosome–mitochondria colocalization, suggesting that the association of purinosomes with mitochondria is facilitated by microtubule-directed transport, and thereby supporting our notion of an interdependency between these subcellular components in maximizing purine production through the de novo purine biosynthetic pathway.