Current Consumption Measurements Research Articles

Precise realtime current consumption measurement in IoT TestBed.

The Internet of Things, similar to wireless sensor networks, has been integrated into the daily life of almost everyone. These wearable, stationary, or mobile devices are in multiple locations, collecting data or monitoring and executing certain tasks. Some can monitor environmental values and interact with the environment, while others are used for data collection, entertainment, or even lifesaving. To achieve the wireless part of the system, the majority of sensor nodes are designed to be battery-powered. While battery power has become increasingly ubiquitous, it tends to increase the global carbon footprint of electronic devices. This issue can be mitigated by employing some form of energy harvesting so that batteries can be refilled and the gadget lasts longer, but this does not alter the reality that batteries are still used and eventually discarded. In this paper, the authors emphasize the significance of power consumption in battery-powered devices. To be able to monitor devices' power consumption, one of the measurable parameters is current. When users know the exact current consumption, they can decrease it by polishing the program or tweaking the duty cycle, making radio transmit fewer data or less frequently, thus decreasing overall power draw. In order to simplify current consumption monitoring, the authors have developed a testbed facility that provides real-time current consumption measurements, which may be used to enhance the duty cycle and battery life of the aforementioned devices. While minimizing total current consumption is a great way to extend the battery life and, thus, the carbon footprint, the primary culprit in the Internet of Things is radio communications. This transmission is the primary source of current consumption. By determining the exact amount of current drawn during transmission and adjusting it, users can significantly extend battery life.

Precise realtime current consumption measurement in IoT TestBed

Background: The Internet of Things, similar to wireless sensor networks, has been integrated into daily life of almost everyone. These wearable, stationary, or mobile devices are in multiple locations, collecting data or monitoring and executing certain tasks. Some can monitor environmental values and interact with the environment, while others are used for data collection, entertainment, or even life-saving. To achieve the wireless part of the system, the majority of sensor nodes are designed to be battery-powered. While battery power has become increasingly ubiquitous, it tends to increase the global carbon footprint of electronic devices. This issue can be mitigated by employing some form of energy harvesting so that batteries can be refilled and the gadget lasts longer, but this does not alter the reality that batteries are still used and eventually discarded. Methods: In this paper, the authors emphasise the significance of power consumption in battery powered devices. To be able to monitor devices power consumption, one of the measurable parameters is current. When users know the exact current consumption, they can decrease it by polishing the program or tweaking the duty cycle, making radio transmit less data or less frequently, thus decreasing overall power draw. Results: In order to simplify current consumption monitoring, the authors have developed a testbed facility that provides real-time current consumption measurements, which may be used to enhance the duty cycle and battery life of the aforementioned devices. Conclusions: While minimising total current consumption is a great way to extend the battery life and, thus, the carbon footprint, the primary culprit in the Internet of Things is the radio communications. This transmission is the primary source of current consumption. By determining the exact amount of current drawn during transmission and adjusting it, users can significantly extend battery life.

LoRaWAN ESL for Food Retail and Logistics

Electronic shelf labels (ESL, or electronic price tag) are used by retailers for displaying product pricing on shelves substituting printed price tags; each ESL can display not only the price, but also text, and images, and can be remotely updated, configured, and programmed from a central server. Additionally, the emerging IoT paradigm, allows to expand the application horizon. Firstly, this work presents an analysis on how the use of Cloud-connected, intelligent, ESLs can improve food logistics in the complex scenarios of medium and large cities. Then, a low-cost ESL device, using an electronic ink (e-ink) display and the LoRaWAN protocol to communicate with the central server, aimed at price display and innovative applications in food retail and logistics, is presented. Several current consumption and communication distance measurements are shown, and the design and configuration space are explored to optimize battery life and communication reliability in the different food distribution scenarios. The proposed ESL is powered with a 500mA ·h LiMnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> battery that can last for >8 years in a typical application, considering it communicates with a central server once per hour. The developed price tag can dynamically update the price and information for the customer, which in the case of food can be used to minimize spoilage and can easily upgraded to incorporate sensors or smartphone interaction to develop innovative food logistics and marketing practices. Finally, a LoRaWAN time-slot allocation strategy is presented, to minimize collisions when thousand nodes are connected to a single gateway, with a minimum power consumption overhead.

Two-Electrode ECG for Ambulatory Monitoring with Minimal Hardware Complexity.

This article introduces a two-electrode ground-free electrocardiogram (ECG) with minimal hardware complexity, which is ideal for wearable battery-powered devices. The main issue of ground-free measurements is the presence of noise. Therefore, noise suppression methods that can be employed for a two-electrode ECG acquisition system are discussed in detail. Experimental measurements of a living subject and patient simulator are used to investigate and compare the performance of the three proposed methods utilizing the ADS1191 analogue front-end for biopotential measurements. The resulting signals recorded for the simulator indicate that all three methods should be suitable for suppressing power-line noise. The Power Spectral Density (PSD) of the signals measured for a subject exhibits differences across methods; the signal power at 50 Hz is −28, −24.8, and −26 dB for the first, second, and third method, respectively. The digital postprocessing of measured signals acquired a high-quality ECG signal comparable to that of three-electrode sensing. The current consumption measurements demonstrate that all proposed two-electrode ECG solutions are appropriate as a battery-powered device (current consumption < 1.5 mA; sampling rate of 500 SPS). The first method, according to the results, is considered the most effective method in the suppression of power-line noise, current consumption, and hardware complexity.

Low-Power and Low-Cost Environmental IoT Electronic Nose Using Initial Action Period Measurements.

In this work, we present a complete hardware development and current consumption study of a portable electronic nose designed for the Internet-of-Things (IoT). Thanks to the technique of measuring in the initial action period, it can be reliably powered with a moderate-sized battery. The system is built around the well-known SoC (System on Chip) ESP8266EX, using low-cost electronics and standard sensors from Figaro’s TGS26xx series. This SoC, in addition to a powerful microcontroller, provides Wi-Fi connectivity, making it very suitable for IoT applications. The system also includes a precision analog-to-digital converter for the measurements and a charging module for the lithium battery. During its operation, the designed software takes measurements periodically, and keeps the microcontroller in deep-sleep state most of the time, storing several measurements before uploading them to the cloud. In the experiments and tests carried out, we have focused our work on the measurement and optimization of current consumption, with the aim of extending the battery life. The results show that taking measurements every 4 min and uploading data every five measurements, the battery of 750 mAh needs to be charged approximately once a month. Despite the fact that we have used a specific model of gas sensor, this methodology is quite generic and could be extended to other sensors with lower consumption, increasing very significantly the duration of the battery.

Power Consumption Analysis of Bluetooth Low Energy Commercial Products and Their Implications for IoT Applications

Internet of things (IoT) has become a very important business segment for the industry since it is estimated that 50 billion devices will be interconnected by 2020, where 30% of them are forecasted to use Bluetooth low energy as the enabling communication protocol. IoT involves smart devices that can be connected to the cloud in order to share and process all types of data collected through sensors. Moreover, 100% of smartphones and tablets shipped in 2018 include Bluetooth low energy, which will allow the interoperation with the upcoming 5G standard. As a result, different low-power hardware platforms have become available to either build prototypes, or implement full IoT solutions. One fundamental aspect while choosing a development platform is to analyze the power consumption of its components to build an optimal low-power application and extend the battery life. In this work, we present current consumption measurements of four Bluetooth low energy commercial platforms configured as central and as peripheral devices, these measurements are aimed to provide the data that are not available in the datasheets and which is needed to select, in an optimal way, the proper connection parameters for the protocol.

Low-cost test measurement setup for real IoT BLE sensor device characterization

The methodology presented in this paper aims to characterize impairments shown by real devices which are usually neglected on standardized tests but that become very important in massive IoT scenarios.For instance, we have measured that real BLE scanners are not able to scan continuously even though they are configured to do so. Besides, we have also found and demonstrated that some manufacturers seem not to apply any backoff mechanism although it is mandatory. These two unexpected behaviors have a significant impact on the performance of massive wireless sensor networks based on BLE. So, it becomes necessary to characterize these and other impairments.The proposed tests are based on device current consumption measurements and their association with the information obtained from upper layers.We describe a new low-cost generic measurement setup and provide all the necessary data (configuration parameters, scripts, etc.) for applying the proposed methodology. As an example, we use it to profile the behavior of Bluetooth Low Energy devices. Furthermore, the proposed setup can also inspire researchers to characterize other wireless technology devices, like Wi-Fi, Zigbee, LoRa, etc.

Design and Performance Evaluation of 4 Wheeled Omni Wheelchair with Reduced Slip and Vibration

Holonomic wheelchairs are being popular for their ability to move in constrained spaces due to their omnidirectional mobility. In this paper we have presented design and development of a 4 wheel driven omni wheelchair suited for indoor navigation with reduced wheel slippage and vibration. The design has been evaluated with wheel load measurement from current consumption and vibration measurement with a 3 axis accelerometer mounted on the chassis. From the result and analysis, it is evident that our proposed design shows less wheel slippage and vibration than existing designs. The system can find its application as an assistive aid for geriatric population or as a smart indoor mobility vehicle.

Investigation of Bluetooth Communications for Low-Power Embedded Sensor Networks in Agriculture

Abstract. Internet of things (IoT) sensor networks that monitor agricultural equipment can provide useful data to optimize a farm‘s productivity. For such a network to become widely adopted, the sensors should have battery lives at least as long as a full farming season. While the standard low-power wireless sensor communication platforms, e.g., Zigbee and ANT, may potentially satisfy this requirement, they lack common hardware support in consumer devices. By using more ubiquitous technology, such as cellphones and tablets, the costs and complexity and be significantly reduced. Nearly all mobile devices currently on the market have Bluetooth capability, making it a viable wireless protocol choice. In addition, the recent release and adoption of the Bluetooth 4.0 Low Energy (BLE) standard has solidified it as a strong candidate for use in very low power, long battery life networking. This work investigates how various BLE configurations affect network size, network throughput, and sensor battery lifetimes. We present a strategy to select network parameters that achieve at least a certain sensor update interval and connection latency while simultaneously minimizing the sensor‘s energy requirements and data latency and conforming to network size and throughput constraints. We present a simple BLE energy model created from current consumption measurements of the commercially available TI CC2540 BLE module. The combination of this BLE energy model and a simple battery capacity model allows the estimation and validation of sufficient battery life. Sensor lifetimes on the order of multiple years can easily be achieved for large update interval and connection latency sensors, which would be typical in mobile agricultural equipment.

A Lithium-Ion Battery Current Estimation Technique Using an Unknown Input Observer

Current consumption measurements are useful in a wide variety of applications, including power monitoring and fault detection within a lithium-ion battery management system (BMS). This measurement is typically taken using either a shunt resistor or a Hall-effect current sensor. Although both methods have achieved accurate current measurements, shunt resistors have inherent power loss and require isolation circuitry, and Hall-effect sensors are generally expensive. This paper explores a novel alternative to sensing battery current by measuring terminal voltages and cell temperatures and using an unknown input observer to estimate the battery current. An accurate model of a LiFePO4 cell is created, validated, and then used to characterize a model of the proposed current estimation technique. Finally, the current estimation technique is implemented in hardware and tested in an online BMS environment. Results show that the current estimation technique is sufficiently accurate for a variety of applications, including fault detection and power profiling.

A Comprehensive Analysis on Sizing of Solar Energy Harvester Elements for Wireless Sensor Motes

Abstract Wireless sensor networks (WSN) have limited lifetime due to on board battery. The lifetime can be improved by energy harvesting solutions. In this paper the solar energy harvester requirements for TelosB mote has been analyzed and calculated. Photovoltaic (PV) panel and battery sizing requirements are calculated by assuming that the mote follows SMAC and TDMA-MAC schedule for image communication. The calculations are validated by comparing it with the parameters calculated from the real time current consumption measurement of the mote. Lifetime has been predicted with the physical design of energy harvester. The analysis confirms that the lifetime of the network can be increased to a greater extent, by proper sizing of the harvester and efficient utilization of the available energy.

Authenticated encryption of pmu data

This paper presents the implementation of an encryption board in order to provide confidentiality, authenticity and integrity of data collected at any point in a power grid, as a potential solution to the Smart Grid cyber security issues. This board consists of a Freescale microcontroller which enables the connection between a PMU (Phasor Measurement Unit) and a ZigBee transmitter. Encryption is done using the SHA256, HMAC-SHA256, KDF-SHA256 and AES256-CBC algorithms. This architecture makes reading and transmission of voltage and current phasors, energy consumption, frequency, power, power factor and power outages measurements, and sends this information in real time to a data concentrator where display and subsequent storage are possible.

Innovative Safety System of Work of Wood Cutting Electric Table Saw, Based on the Measurement of Current Consumption

The main objective of the study was to develop an innovative safety system of wood cutting electric table saws, based on measurements of power consumption. Practical use of the proposed technical solution is a prolonged lifetime of the cutter and its blade, reduction of the risk of overheating due to friction of treated wood - which can lead to ignition of wood and wood dust, and therefore reduce the risk of occurrence of the accident, a fire or an injury. Further research directions were indicated.

A Current Consumption Measurement Approach for FPGA-Based Embedded Systems

In this paper, an approach for the current-consumption measurement of a field-programmable gate array (FPGA)-based embedded system is presented. This approach is based on the current conversion to pulsewidth using the external-to-FPGA capacitor charging circuit and comparator. The pulsewidth is then measured using the timer synthesized inside the FPGA. Measurement uncertainty budget analysis is performed. It reveals the parameters mostly affecting steady-state current measurement uncertainty. Sources contributing to the budget of current measurement uncertainty include directly measured pulsewidth, manufacturing scattering of measurement setup component parameters, and their fluctuations in response to the measured current value. A calibration procedure enabling to reduce the influence of charging circuit component manufacturing tolerances on measurement uncertainty is suggested. The current measurement prototype is developed and tested. Measured pulsewidth jitter is estimated experimentally using the prototype. The jitter influence on measurement uncertainty is modeled by including the corresponding quantity in the measurement model. The influence of the temperature on measurement uncertainty is estimated using Monte Carlo simulation.

An Assessment of the Electric Power Quality and Electrical Installation Impacts on Medical Electrical Equipment Operations at Health Care Facilities

Problem statement: Medical electrical equipments at health care facilities presented malfunction and wrong medical information due to poor electric power quality and to inadequate electrical Installations. Some equipment such as X-ray, computerized axial tomography and magnetic resonance imaging are considered as polluting ones due to their high amount of harmonics and voltage transients produced on the electrical power supply when in operation, while other equipments, connected to the same power supply, are considered sensitive or victim ones, presenting failure or producing wrong. Approach: The effects on some sensitive medical electrical equipment were verified in a controlled environment at energy quality technological center of the technical school of the University of Sao Paulo. A heart monitor, pulmonary ventilator and pulse oxymeter equipment types were submitted to a controlled voltage supply with high harmonic content and voltage sags. The test methodology used simulated conditions based on Brazilian NBR standards, ANSI/IEEE Std. 519, IEC 60601 and IEC 61000-4-11 standards. Results: The results of the polluting equipment current consumption measurements as well as the three sensitive equipments tested were presented and discussed. The pulmonary ventilator presented problems that range from stoppage to expiratory valve blockage and alarm system failures. The pulse oxymeter presented display malfunctions and it was extremely sensitive to voltage sags. The heart monitor maintained steady operation in all test cases. Conclusion/Recommendations: In spite of several existing recommendations and standards for testing medical electrical equipments, there is a lack of standard related to test cases considering the effects of high harmonic and voltage sags. The quality of electrical installation in health care facilities needs to be improved to reduce risks to the patients and to provide better health treatment.

Oxygen consumption and chloride secretion in rat distal colon isolated mucosa.

The aerobic metabolic cost of chloride secretion was studied in rat distal colon isolated mucosa under several conditions by simultaneous measurement of short-circuit current and oxygen consumption under conditions that preserve vectorial ion transport. A low-chloride solution and the presence of bumetanide plus diphenylamine-2-carboxylate reduced short-circuit current by 75% and oxygen consumption by 25%. Ouabain decreased short-circuit current by 93% and oxygen consumption by 32%. Serotonin increased both variables by 59% and 33%, respectively. Bumetanide and diphenylamine-2-carboxylate reduced but did not abolish the effect of serotonin on short-circuit current and oxygen consumption. Changes in short-circuit current and oxygen consumption were linearly correlated under all conditions tested. It is concluded that, in the unstimulated rat distal colon epithelium, chloride secretion accounts for about 75% of ouabain-sensitive short-circuit current and oxygen consumption. Stimulated chloride secretion may demand over 40% of total oxygen consumption.

Measurement of oxygen consumption in voltage-clamped epithelia

Standard apparatus for in vitro study of anuran epithelia was adapted for the incorporation of Clark oxygen electrodes, permitting the concurrent measurement of electrical current (active sodium transport) and oxygen consumption under voltage-clamp conditions, with independent manipulation of the two bathing solutions. Stability was enhanced by electrical isolation of the O2 electrodes, sensitive temperature control (+/- 0.03 degrees C), and constancy of stirring rate. Mean rate of drift was less than 3.7% of the average rate of basal (i.e., nontransport related) O2 consumption. In the present configuration the response time was less than 15 s. Visual fitting of slopes of O2 tension evaluated rates of O2 consumption with adequate accuracy in the physiological range (basal rates averaged about 20 pmol-s-1-cm-2 toad bladder, corresponding to about 10 pmol-s-1-mg-1 dry wt, or about 5 pmol-s-1-ml-1 chamber volume). Rpresentative slopes were read with a standard deviation of 3.5%.