Low-cost Prototype Research Articles

A new static method of calibration for low-cost laser triangulation systems

As a non-contact high-efficiency method, laser triangulation has long been studied by many scholars. Building such a system usually requires calibration where system parameters are found or amended to achieve the targeted precision. Traditional calibration methods require using either precise movement or high precision gauge object that are accompanied with extra manufacturing cost and auxiliary equipment/devices and hence increase the overall cost as well as prevent widespread applications, for instance, due to required environment conditions to be fulfilled. A new static method was, therefore, proposed to calibrate a system without need of a motion or a high precision gauge object to be deployed. The method relies on preparation of the data on a scalar compound target with a geometric estimator as quality indicator. Based on this method, three versions of a low-cost prototype were built, which achieved sub-millimeter precision. Although the precision is sufficient for a measurement often used manufacturing large panels, higher precision is achievable with additional work which is to be undertaken in the future. The proposed method makes tradeoff between precision and cost. This was followed by testing on the measurement of a small panel part as application-case study. The proven feasibility of the method proposed suggested potential of developing low-cost, inline industrial system (large or small) for inspecting sheet parts during manufacturing, especially panel component manufacturing, including that from metal sheets and composite materials.

A Low-Cost Prototype to Automate Agricultural Sprayers

The world’s population growth in the last decades demanded a great increase in agricultural production, especially in food. Therefore, in order to reduce possible losses and guarantee productivity, farmers depend more and more on the application of agrochemicals in their crops. This massive use of pesticides represents not only a high cost to the farmers but also a risk to their health, to the environment and even to the safety of the food consumed by the population. In this context, new technologies have been developed to make agricultural spraying more effective, reducing the amount of pesticide applied and dosing its use according to the need of the crop. The recognition of its spatial and temporal variability is treated by Precision Agriculture. In the case of pest management it can be done using variable-rate sprayers or using on/off application with individual nozzle control. Thus, this paper proposes a low-cost prototype in a modular solution to automate existent agricultural sprayers. The solution allows individual nozzle opening, with on/off control, using solenoid valves, pressure and flow sensors, Arduino boards, and smartphone. Additionally, the prototype has a data logger function to store nozzle status and sensor values, allowing future analysis and application reports.

A multi-functional BCI system for exigency assistance and environment control based on ML and IoT

Brain-Computer Interface (BCI) is a modality to create an interface which sustains bidirectional communication between the brain and computers. Major disadvantages in implementing such systems are the bulky design and system cost. This study implements a simple multifunction BCI system for the environment control and exigency assistance by just using single channel Electroencephalogram (EEG). In the proposed model, the environment is controlled through Internet of Things (IoT) as per individual's cognitive state while for exigency assistance served as per Event Related Potential (ERP) observed during oddball paradigm. Arduino microcontroller (AMC) hardware is designed for controlling environment. Different Machine Learning (ML) algorithms observed for training the classifiers. Weighted k-Nearest Neighbour (Wk-NN) algorithm trained classifier delivers the best result, with accuracy of 98.3% to detect ERP and 95% accuracy for cognitive state detection. The simple, low cost prototype system was tested for environment control and assistance.

A multi-functional BCI system for exigency assistance and environment control based on ML and IoT

Brain-Computer Interface (BCI) is a modality to create an interface which sustains bidirectional communication between the brain and computers. Major disadvantages in implementing such systems are the bulky design and system cost. This study implements a simple multifunction BCI system for the environment control and exigency assistance by just using single channel Electroencephalogram (EEG). In the proposed model, the environment is controlled through Internet of Things (IoT) as per individual's cognitive state while for exigency assistance served as per Event Related Potential (ERP) observed during oddball paradigm. Arduino microcontroller (AMC) hardware is designed for controlling environment. Different Machine Learning (ML) algorithms observed for training the classifiers. Weighted k-Nearest Neighbour (Wk-NN) algorithm trained classifier delivers the best result, with accuracy of 98.3% to detect ERP and 95% accuracy for cognitive state detection. The simple, low cost prototype system was tested for environment control and assistance.

A Low-Cost, Portable Solution for Stress and Relaxation Estimation Based on a Real-Time Fuzzy Algorithm

Goal: This paper proposes a reliable stress and relaxation level estimation algorithm that is implemented in a portable, low-cost hardware device and executed in real time. The main objective of this work is to offer an affordable and “ready-to-go” solution for medical and personal environments, in which the detection of the arousal level of a person is crucial. Methods: To achieve meaningful identification of stress and relaxation, a fuzzy algorithm based on expert knowledge is built according to parameters extracted from physiological records. In addition to the heart rate, parameters extracted from the galvanic skin response and breath are employed to extend the results. Moreover, this algorithm achieves accurate results with a restricted computational load and can be implemented in a miniaturized low-cost prototype. The developed solution includes standard and actively shielded electrodes that are connected to an Arduino device for acquisition, while parameter extraction and fuzzy processing are conducted with a more powerful Raspberry Pi board. The proposed solution is validated using real physiological registers from 42 subjects collected using BIOPAC MP36 hardware. Additionally, a real-time acquisition, processing and remote cloud storage service is integrated via IoT wireless technology. Results: Robust identification of stress and relaxation is achieved, with F1 scores of 91.15% and 96.61%, respectively. Moreover, processing is performed using a 20-second sliding window; thus, only a small frame of context is required. Significance: This work presents a reliable solution for identifying stress and relaxation levels in real time, which can lead to the production of low-cost commercial devices for use in medical and personal environments.

Development and Implementation of a Low Cost μC- Based Brushless DC Motor Sensorless Controller: A Practical Analysis of Hardware and Software Aspects

The ongoing technological advancements of brushless DC motors (BLDCMs) have found a wide range of applications. For instance, ground-based electric vehicles, aerial drones and underwater scooters have already adopted high-performance BLDCMs. Nevertheless their adoption demands control systems to monitor torque, speed and other performance characteristics. Precise design structure and the particular motor functional characteristics are essential for the suitable configuration and implementation of an appropriate controller to suit a wide range of applications. Techniques which do not use Hall sensors should be used then. This paper deals with the analysis of hardware and software aspects during the development of such a microcontroller based and low cost speed controller for motors up to 500 W, along with its practical implementation. The sensorless method employed is based on the zero crossing point (ZCP) detection of the back-electromotive forces’ (back-EMF) differences, as the ZCPs of these quantities match to the time points at which the commutation sequence changes. Additionally, the study presents hardware and software details through calculations, figures, flowcharts and code, providing an insight of the practical issues that may arise in such a low cost prototype. Finally, results obtained by experiments validate the presented hardware/software architecture of the controller.

A Student Smart Parking Solution using Raspberry Pi

The concept of a smart city was born out of the need to provide improved quality of life to citizens in various fields, such as environment, governance, education, economy, infrastructure, transportation, traffic, and parking. There are many countries, many players and many projects already finished or underway. The city of Timisoara has already taken the first steps towards a smart city. It has high potential in this regard, but for the moment is still lacking in some key areas. For example, Timisoara has excessive traffic and usually overcrowded parking lots without some efficient monitoring solutions. As a result of this fact, a team made up of a Master student in his second year of studies, and two faculty coordinating members propose a parking management solution based on a very restrictive budget. The low-cost prototype we developed for testing purposes contains a mockup parking platform with 8 parking spaces, one Raspberry Pi Zero W micro-computer, and a camera module attached to the Raspberry Pi. The idea is to broadcast live feed towards a computing platform tasked with identifying the available parking spots and consequently transmit this information in real-time, via the Internet, to interested parties. We tested and compared two detection algorithms based on corner detection of the parking spots, and the detection of circles placed inside the parking spot, respectively. These algorithms were implemented using open-source technologies such as Python version 3.6.5, OpenCV 3.4.0 specialized modules and functions, digital processing (NumPy), chart plotting (Matplotlib) and data formatting (JSON). The main functions we used were: cv2.imread, cv2.imshow, cv2.imwrite, cv2.VideoCapture, cv2.line, cv2.circle, cv.puttext, cv2.rectangle, cv2.elipse, cv2.blur, cv2.gaussianblur, cv2.canny, cv2.houghlinesp, cv2.houghcircles, cv2.hough_gradient and cv2.selectROI. The solution we proposed is focused on improving the way the Politehnica University Timisoara’s staff and students approach parking. It can reduce traffic congestion and the level of CO2 or other pollutants around University buildings and surrounding areas. Overall traffic would be greatly diminished because the driving lanes would mainly be used for transportation, instead of low-speed cruising in search of a free parking space.

From real to virtual eyes

The change in the color of the vegetables peel during the ripening process is the main criterion used by the consumer to define the fruit ripeness degree and for the producer to determine the best time of harvest. This relationship between bark coloration and different maturation stages allows the producer to establish harvest planning and extend shelf life. Students and faculty of the Biosystems Engineering course at São Paulo State University (UNESP), Tupã Campus, designed and developed a low-cost prototype of a fruit sorting belt, specifically for cherry group tomatoes. In the future, improvement in machinery with the insertion of new devices such as cameras, embedded system, combines sensor technology 3.0 with machine learning 4.0.

Feasibility of a photoelectric sensor technique for nondestructive prediction of granulation disorder in tangerines

Granulation is a physiological disorder in Tangerine (Citrus reticulata) that can cause an internal disorder which cannot be determined by visual inspection. A nondestructive technique, which is simple and low cost, that could determine whether an individual fruit suffered from granulation would be of help to the citrus industry. The intensity signal of photoelectric sensor, when light passed through tangerines ‘Keaw Dumnuan’ was investigated and showed that the signal was significantly larger (p < 0.05) for normal tangerines and those suffering from granulation. In order to determine a suitable non-destructive method for detect granulation disorder in tangerines that could be applied commercially, a simple and low cost prototype of this photoelectric sensor technique was developed. A set of 52 fruit were used and their average intensity signal from four measurements was used for discriminant analysis. The cut off value of 61.7 mV was used for classification. If a fruit had the signal intensity equal to or less than 61.7 mV, it had granulation, while fruit that had the signal intensity of more than 61.7 mV was normal. Using this signal intensity discrimination the accuracy of classification was 90.4%. It was also shown that the accuracy of prediction was related to the severity of granulation in each fruit. Therefore, the photoelectric sensor technique was shown to be feasible for use in nondestructively detect of granulation in tangerines and be possibly used in future grading systems.

ClothSurface: Exploring a Low-Cost Prototyping Tool to Support Ideation for Shape Displays

A shape-changing user interface is a type of interface that interacts with users by changing its physical form. Although researchers have been extensively studying shape-changing user interfaces, relevant research on its various design aspects—including tools and methods—remains limited. Prototyping shape-changing interfaces often requires sophisticated equipment and knowledge, which makes this sphere of design unwelcoming for designers with limited resources and technical knowledge (e.g., design students). In this study, we propose ClothSurface—a simple and low-cost prototyping tool to design for shape displays—and explore its use through a series of design sessions. The results reveal that ClothSurface can allow inexperienced designers to illustrate their ideas and to explore the design space of shape displays.

The Handy Metaphor: Bimanual, touchless interaction for the internet of musical things

We describe the development of a new ubiquitous music metaphor for creative action involving the use of hand gestures, Handy. The metaphor was deployed through two proof-of-concept, low-cost prototypes based either on motion sensors connected to an embedded micro-controller (Handy H) or by repurposing the webcam of a portable computer (Handy S). The evaluations showed positive results (slightly better with musicians than with non-musicians) in the following factors: ease of use and productivity (Handy H); engagement, productivity and collaboration support (Handy S). We discuss the implications of this outcome, targeting the interaction with the Internet of Musical Things.

FPGA-based hardware-in-the-loop for multi-domain simulation

In this paper, we present a new approach for complex system design, which allows rapid, efficient and low-cost prototyping. This approach can simplify designing tasks and go faster from system modeling to effective hardware implementation. Designing multi-domain systems requires different engineering competences and several tools, our approach gives a unique design environment, based on the use of VHDL-AMS modeling language and FPGA device within the same design tool. This approach is intended to enhance hardware-in-the-loop (HIL) practices with a more realistic simulation which improve the verification process in the system design flow. This paper describes the implementation of a software/hardware platform as a practical support for our approach, the feasibility and the benefits of this approach are demonstrated through a practical case study for power converter control. The obtained results show that the developed method achieves significant speed-up compared with conventional simulation, with a minimum used resources and minimum latency.

Direct laser writing to fabricate capacitively transduced resonating sensor

This article reports on laser technology based fabrication approach to develop a micro-size capacitive gap based transducer useful for a variety of applications. A low-cost prototype has been fabricated via a rapid and advanced laser micro-milling technique to achieve a parallel kerf-width (capacitive gaps) of about 60 µm into a piece of aluminum and a stainless steel each of 1 and 2 mm thickness, respectively, thus leading to a high-aspect ratio (> 33) structure. A device is demonstrated to facilitate actuation via electrostatic means and sense a capacitive change across its electrode. Experiments have been performed with a structure made of aluminum. Results comprising analytical modeling, fabrication, and electrical characterization are presented. An applicability of a device as a two degree-of-freedom resonating mode-localization sensor that employs a weak electrostatic coupling is demonstrated to offer vibration amplitude based sensitivity to a relative change in the stiffness. This sensor is able to resolve a minimum stiffness perturbation (normalized), $$\delta_{{k_{\rm{min} } }} = \frac{\Delta k}{{K_{eff} }}$$ of the order of 7.98 × 10−4.

Sustainability Metrics for Housing and the Thermal Performance Evaluation of a Low-Cost Prototype Made with Poly (Ethylene Terephthalate) Bottles

The scope of this work covers a proposal for the implementation of sustainable, low-cost, environmentally friendly, and affordable housing for low-income people. This paper aims to address the current housing issues, namely that many people lack decent housing and that the built houses are usually of a poorly sustainable nature. The work consists of three main parts: an evaluation of housing sustainability, measurement of parameters related to their internal comfort and a simulation of thermal enclosure with the COMSOL Multiphysics® software. An important objective is to propose a sustainability assessment format, which, besides being explained in detail, is presented in a percentage scale for ease of understanding. This work seeks a methodology for evaluating the level or degree of sustainability for the construction and inhabitation stages of housing. Using a prototype constructed with polyethylene terephthalate (PET) bottles, temperature and humidity were measured. There was a contrasting behavior of these two parameters, which tended towards an inverse behavior, except on cloudy or rainy days. The roof of the prototype contained some waste materials that provided thermal insulation: galvanized steel, polyethylene bags for upcycling as waterproofing, PET bottles, soil and endemic plants (green roof). The results obtained in the simulation are in accordance with the real internal behavior of the prototype.

Low Cost Wavelength Specific Water Quality Measurement Technique.

Optical sensing for chemical analysis is emerging as it provides advantages such as good sensitivity, selectivity, electromagnetic immunity, etc. This work presents a low-cost, robust and easy to use technique for measurement of bulk water property changes, specifically pH, total dissolved solids (TDS), and turbidity. The designed multi-wavelength sensing mechanism is capable of measuring the absorption of light emitted by three different LEDs after passing through water. The optical responses obtained using this mechanism are then related to parameter changes of water for quality measurement. The results show that measurements for pH, TDS, and turbidity have a linear regression coefficient of 0.9691, 0.9729 and 0.76 respectively. By utilizing narrowband light sources of characteristic wavelengths for the target parameters, a compact and portable device can be designed for rapid measurements. This can work as a replacement of spectrophotometers for parameter specific measurements of water quality and a low cost prototype (costing ~ 20 $) for the same has been demonstrated.

A Low-Cost Chamber Prototype for Automatic Thermal Analysis of MEMS IMU Sensors in Tilt Measurements Perspective.

In this work, a low-cost, open-source and replicable system prototype for thermal analysis of low-cost Micro Electro-Mechanical Systems (MEMS) Inertial Measurement Unit (IMU) sensors in tilt measurement perspective is presented and tested. The system is formed of a 3D printed frame, a thermal cell consisting in a Peltier element mounted over a heat sink, and a control and power system. The frame is designed to allow the independent biaxial tilting of the thermal cell through two servomotors. The control board is formed by an Arduino® and a self-made board including a power drive for controlling the thermal unit and servomotors. We tested the chamber analyzing the behavior of multiple MEMS IMU onboard accelerometers suitable for measuring tilt. Our results underline the variability of the thermal behavior of the sensors, also for different sensor boards of the same model, and consequently the need for the adoption of a thermal compensation strategy based on thermal analysis results. These data suggesting the need for the analysis of the thermal behavior of MEMS-based sensors, indicate the potential of our system in making low-cost sensors suitable in medium-to-high precision monitoring applications.

Prototype of multifunctional transmitter with Rejection of disturbances

The industrial instruments found in the different industrial processes allow supervisory and control actions to be carried out. These elements are usually composed of an electronic circuit, which varies according to the specifications given by the manufacturer. Another factor that influences the design of a circuit for elements of this type is cost, since, at a lower cost, electronic elements are susceptible to fail for reasons such as electric fields, motor interference or environmental conditions. This problem limits the operation of the instrument and reduces its useful life, which causes unnecessary stops of the automated processes increasing the cost of producing a product. Some partial solutions to this problem have been obtained by means of the implementation of additional circuits such as protections or filters, although the number of unexpected stops of the process is reduced, even this type of failures occur. This paper proposes an alternative solution to the problem through a low cost prototype, which has a mechanism for rejection of disturbances that increases the accuracy and precision of an instrument compared to the low-cost instrument technology developed so far.

Diseño e implementación de un sistema de comunicaciones basado en luz visible

Introducción: El artículo es produto de la investigación: “Prototipo de un sistema de telecomunicaciones basado en luz visible”, realizado en la Universidad del Valle en el año 2018. Objetivo: El objetivo de este trabajo fue construir un prototipo funcional de un sistema de telecomunicaciones basado en luz visible a través del cual se pueda realizar el estudio de las características, elementos y comportamientos más relevantes en relación con esta tecnología. Metodología: Para estudiar el comportamiento del prototipo desarrollado, se realizaron diferentes pruebas que variaron algunas de las variables presentadas en este tipo de sistemas de telecomunicaciones. Además, el prototipo desarrollado se probó en los modos simplex y halfduplex. Conclusiones: Los resultados obtenidos al desarrollar este trabajo permitieron encontrar las características principales del prototipo, sus limitaciones, así como los elementos y variables que rigen un papel fundamental en su diseño. Originalidad: El diseño presentado propone el desarrollo de un prototipo de bajo costo, capaz de obtener los datos que se enviarán a través de la conexión a otros dispositivos a través de diferentes periféricos de comunicación o usar el ADC presente en el dispositivo de procesamiento utilizado. Limitación: Debido a los elementos de recepción utilizados en el prototipo, existe una limitación significativa en la velocidad de transmisión máxima alcanzable. Además, es importante mencionar que las condiciones en las que se implementa el prototipo pueden afectar su comportamiento, por ejemplo, los elementos que impiden la línea de visión entre los módulos de telecomunicaciones pueden detener la transmisión.

SpaceCAN - A low-cost, reliable and robust control and monitoring bus for small satellites

The control and monitoring bus is the backbone for routing commands and telemetry among spacecraft subsystems. Typically, a central processing unit is commanding other intelligent nodes (such as the power system, communication system, and payloads) and collects status information from them. The data to be exchanged on this bus is of moderate volume but must be transmitted in a reliable way. Most commonly for small satellites, and in particular CubeSats, the I2C bus is used as main system bus. This is a problem because the I2C bus is not fault tolerant and has been reported as the source of mishaps to a number of satellite missions. We propose to replace I2C bus with CAN bus, which is heavily employed in automotive and industrial applications since decades and has been qualified for use in space. For this, we have developed the SpaceCAN protocol, which utilizes CAN as transport technology and combines elements of ECSS CAN Bus Extension Protocol for reliability and robustness, and the ISO-TP protocol for large message transfer. With the help of a low-cost prototype we validate the protocol features and contrast its performance against the I2C bus. The results demonstrate that SpaceCAN is superior to I2C in terms of reliability and robustness to failures. The main obstacle to an immediate replacement of I2C is the increased power consumption of the CAN bus, for which we outline strategies for improvement. The entire prototype source code is available under a permissive open source license.

Development and Experimental Verification of an XY-Table for the Optimization of the Alignment of High-Power Gyrotrons

The proper alignment of the electron beam with the interaction cavity is essential in order to achieve efficient operation of modern high-power, high-frequency gyrotrons. However, tolerances, manufacturing, and magnetic field alignment errors may lead to the less optimal positioning of the electron beam in the gyrotron cavity. In this paper, we describe in detail the in-house design and development of a simple and low-cost prototype gyrotron-alignment XY-table, which can be used for the optimization of the alignment of the electron beam with the cavity axis. The efficient operation of the device is verified experimentally by operating the European ITER 170-GHz, 1-MW short-pulse prototype gyrotron in the Oxford Instruments superconducting magnet that is available at the Karlsruhe Institute of Technology gyrotron test-stand and is equipped with a set of dipole coils.