Internet of things (IoT) is increasingly useful in connecting network of devices on the internet. A popular need of IoT in the industry is to measure the level of the liquid in a faraway tank of interest. The traditional measurement method uses float, pressure or ultrasonic sensor and provides reliable results. Nonetheless, the disadvantages of traditional methods are that their range of measurement is rather short and their maintenance on the field is also difficult. To solve these problems, we propose a novel method that combines the image processing algorithm with Node-Red IoT systems. The original idea of this paper is to use the image of the ruler on the tank for measuring the physical height of liquid level in standard units. Our experimental results on real-time collected images via IoT live-streaming show that our proposed method is very fast and robust with different size and shape of different rulers. Our method is also accurate enough to facilitate the application of liquid level measurement in practice.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

The paper deals with the utilization of Kalman filter and fuzzy logic control in induction motor drive with direct torque control (DTC). In order to lower ripple of stator current vector in DTC drive, pulse width modulation technique with high switching frequency is applied. However, the performance of the DTC also depends on the accuracy of both stator resistance and stator current vector. In the paper, the stator resistance and stator current components are assumed to be distorted by Gaussian noises. In order to reduce the effect of noises especially at low speed and very low speed regions, a simple Kalman filter is applied for filtering current components, and fuzzy logic theory is used to increase the flexibility of proportional-integral (PI) compensator in the speed controller of the drive structure. Simulations are implemented in conditions of high-level noises of stator current and stator resistance, and a wide range of load torque. An ITAE-based criterion is utilized to evaluate the performance of drive structures. Results confirmed the expected dynamic properties of the proposed drive structure. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.