Vision-Based Real-Time Layer Error Quantification for Additive Manufacturing

2017 ◽  
Author(s):  
Haedong Jeong ◽  
Minsub Kim ◽  
Bumsoo Park ◽  
Seungchul Lee
Keyword(s):  
Quality Assurance ◽  
Additive Manufacturing ◽  
Real Time ◽  
Closed Loop ◽  
Open Loop ◽  
Time Layer ◽  
Error Quantification ◽  
Novel Approach ◽  
Test Models ◽  
Comparison Of The Results

Quality assurance of Additive Manufacturing (AM) products has become an important issue as the AM technology is extending its application throughout the industry. However, with no definite measure to quantify the error of the product and monitor the manufacturing process, many attempts are made to propose an effective monitoring system for the quality assurance of AM products. In this research, a novel approach for quantifying the error in real-time is presented through a closed-loop vision-based tracking method. As conventional AM processes are open-loop processes, we focus on the implementation of real-time error quantification of the products through the utilization of a closed-loop process. Three test models are designed for the experiment, and the tracking data from the camera will be compared with the G-code of the product to evaluate the geometrical errors. The results obtained from the camera analysis will then be validated through comparison of the results obtained from a 3D scanner.

scholarly journals Generic characterization of electrical test benches for AC- and HVDC-connected wind power plants

2020 ◽  
Vol 5 (2) ◽  
pp. 561-575
Author(s):  
Behnam Nouri ◽  
Ömer Göksu ◽  
Vahan Gevorgian ◽  
Poul Ejnar Sørensen
Keyword(s):  
Real Time ◽  
Wind Power ◽  
Wind Turbines ◽  
Closed Loop ◽  
Short Circuit ◽  
Open Loop ◽  
Device Under Test ◽  
Generic Structure ◽  
Electrical Test ◽  
Grid Connection

Abstract. The electrical test and assessment of wind turbines go hand in hand with standards and network connection requirements. In this paper, the generic structure of advanced electrical test benches, including grid emulator or controllable grid interface, wind torque emulator, and device under test, is proposed to harmonize state-of-the-art test sites. On the other hand, modern wind turbines are under development towards new features, concerning grid-forming, black-start, and frequency support capabilities as well as harmonic stability and control interaction considerations, to secure the robustness and stability of renewable-energy-based power systems. Therefore, it is necessary to develop new and revised test standards and methodologies to address the new features of wind turbines. This paper proposes a generic test structure within two main groups, including open-loop and closed-loop tests. The open-loop tests include the IEC 61400-21-1 standard tests as well as the additional proposed test options for the new capabilities of wind turbines, which replicate grid connection compliance tests using open-loop references for the grid emulator. In addition, the closed-loop tests evaluate the device under test as part of a virtual wind power plant and perform real-time simulations considering the grid dynamics. The closed-loop tests concern grid connection topologies consisting of AC and HVDC, as well as different electrical characteristics, including impedance, short-circuit ratio, inertia, and background harmonics. The proposed tests can be implemented using available advanced test benches by adjusting their control systems. The characteristics of a real power system can be emulated by a grid emulator coupled with real-time digital simulator systems through a high-bandwidth power-hardware-in-the-loop interface.

scholarly journals Design Considerations for Long Term Non-invasive Brain Computer Interface Training With Tetraplegic CYBATHLON Pilot

2021 ◽  
Vol 15 ◽  
Author(s):  
Neethu Robinson ◽  
Tushar Chouhan ◽  
Ernest Mihelj ◽  
Paulina Kratka ◽  
Frédéric Debraine ◽  
...  
Keyword(s):  
Real Time ◽  
Closed Loop ◽  
Brain Computer Interface ◽  
Brain Activation ◽  
Classification Performance ◽  
Open Loop ◽  
Computer Interface ◽  
Single Subject ◽  
User Engagement

Several studies in the recent past have demonstrated how Brain Computer Interface (BCI) technology can uncover the neural mechanisms underlying various tasks and translate them into control commands. While a multitude of studies have demonstrated the theoretic potential of BCI, a point of concern is that the studies are still confined to lab settings and mostly limited to healthy, able-bodied subjects. The CYBATHLON 2020 BCI race represents an opportunity to further develop BCI design strategies for use in real-time applications with a tetraplegic end user. In this study, as part of the preparation to participate in CYBATHLON 2020 BCI race, we investigate the design aspects of BCI in relation to the choice of its components, in particular, the type of calibration paradigm and its relevance for long-term use. The end goal was to develop a user-friendly and engaging interface suited for long-term use, especially for a spinal-cord injured (SCI) patient. We compared the efficacy of conventional open-loop calibration paradigms with real-time closed-loop paradigms, using pre-trained BCI decoders. Various indicators of performance were analyzed for this study, including the resulting classification performance, game completion time, brain activation maps, and also subjective feedback from the pilot. Our results show that the closed-loop calibration paradigms with real-time feedback is more engaging for the pilot. They also show an indication of achieving better online median classification performance as compared to conventional calibration paradigms (p = 0.0008). We also observe that stronger and more localized brain activation patterns are elicited in the closed-loop paradigm in which the experiment interface closely resembled the end application. Thus, based on this longitudinal evaluation of single-subject data, we demonstrate that BCI-based calibration paradigms with active user-engagement, such as with real-time feedback, could help in achieving better user acceptability and performance.

A novel approach to SBRT patient quality assurance using EPID-based real-time transit dosimetry

2020 ◽  
Vol 196 (2) ◽  
pp. 182-192 ◽  
Author(s):  
Christos Moustakis ◽  
Fatemeh Ebrahimi Tazehmahalleh ◽  
Khaled Elsayad ◽  
Francis Fezeu ◽  
Sergiu Scobioala
Keyword(s):  
Quality Assurance ◽  
Real Time ◽  
Novel Approach ◽  
Transit Dosimetry

scholarly journals Real-time synthesis of imagined speech processes from minimally invasive recordings of neural activity

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Miguel Angrick ◽  
Maarten C. Ottenhoff ◽  
Lorenz Diener ◽  
Darius Ivucic ◽  
Gabriel Ivucic ◽  
...  
Keyword(s):  
Real Time ◽  
Neural Activity ◽  
Communication Channel ◽  
Closed Loop ◽  
Open Loop ◽  
Depth Electrodes ◽  
Whispered Speech ◽  
Frontal Activity ◽  
Synthesis Approach

AbstractSpeech neuroprosthetics aim to provide a natural communication channel to individuals who are unable to speak due to physical or neurological impairments. Real-time synthesis of acoustic speech directly from measured neural activity could enable natural conversations and notably improve quality of life, particularly for individuals who have severely limited means of communication. Recent advances in decoding approaches have led to high quality reconstructions of acoustic speech from invasively measured neural activity. However, most prior research utilizes data collected during open-loop experiments of articulated speech, which might not directly translate to imagined speech processes. Here, we present an approach that synthesizes audible speech in real-time for both imagined and whispered speech conditions. Using a participant implanted with stereotactic depth electrodes, we were able to reliably generate audible speech in real-time. The decoding models rely predominately on frontal activity suggesting that speech processes have similar representations when vocalized, whispered, or imagined. While reconstructed audio is not yet intelligible, our real-time synthesis approach represents an essential step towards investigating how patients will learn to operate a closed-loop speech neuroprosthesis based on imagined speech.

Microassembly via Coordinated Manipulation of Objects Using a Multifingered Micromanipulator

2011 ◽  
Author(s):  
Christopher Pelzmann ◽  
Laxman Saggere
Keyword(s):  
Closed Loop ◽  
State Of The Art ◽  
Control Strategies ◽  
Open Loop ◽  
Open Loop Control ◽  
Multiple Objects ◽  
Loop Control ◽  
Micro Scale ◽  
Novel Approach ◽  
On Chip

This paper presents a novel approach to manipulation and assembly of micro-scale objects using a chip-scale multi-fingered micromanipulator, in which multiple, independently controlled compliant fingers coordinate with each other to grasp and manipulate multiple objects simultaneously on-chip. The structural and functional advantages of this multi-fingered micromanipulator in achieving high dexterity in a compact form as compared to other state-of-the-art manipulation tools are discussed. A formulation of the kinematics of the manipulator’s compliant fingers along with two different control strategies including an operator-driven closed-loop control and a semi-autonomous open-loop control for coordinated manipulation and on-chip assembly of micro-scale objects are introduced. Finally, the details of implementation of both control strategies and successful experimental demonstration of manipulations and assembly of two interlocking micro-scale parts with sub-micron mating clearance using the multifingered manipulator are presented.

scholarly journals Design of a Research Laboratory Drive System for a Synchronous Reluctance Motor for Vector Control and Performance Analysis

Inventions ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 64
Author(s):  
Hamidreza Heidari ◽  
Anton Rassõlkin ◽  
Ants Kallaste ◽  
Toomas Vaimann ◽  
Ekaterina Andriushchenko ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Vector Control ◽  
Real Time ◽  
Research Laboratory ◽  
Closed Loop ◽  
Open Loop ◽  
Drive System ◽  
Control Algorithms ◽  
Synchronous Reluctance Motor ◽  
Reluctance Motor

Motor-drive systems have the most significant share in industrial energy consumption, which requires a deep study in every aspect of the field. This paper presents a synchronous reluctance motor (SynRM) drive system based on Plecs RT box 1. The system’s design provides the opportunity for the open-loop and closed-loop control of the motor and a characteristic performance analysis of the motor. This paper focuses on the hardware implementation of a research laboratory setup and the precise vector control of the SynRM in real-time. The application of the digital controller and inverter to drive SynRM is examined. The voltage, current, and speed transducers were employed for monitoring the protective measures and to control the motor in the closed-loop. The design of the signal conditioning and the intermediary cards for isolation and data acquisition are described in detail. An algorithm is proposed to measure the whole system parameters, including motor, inverter, and cables. Thanks to the RT box 1, the principle of real-time simulation of control algorithms is investigated, and the rapid control prototyping of field-oriented control (FOC) of SynRM was implemented. The simulation of the system was carried out in the Plecs platform, and the results are presented. The experimental results of the implemented control algorithms validate the setup’s performance and the control algorithm. Finally, as a study of the motor’s performance, the efficiency map of the motor is drawn in different speed and torque ranges.

scholarly journals Clinical applications of neurochemical and electrophysiological measurements for closed-loop neurostimulation

2020 ◽  
Vol 49 (1) ◽  
pp. E6 ◽  
Author(s):  
J. Blair Price ◽  
Aaron E. Rusheen ◽  
Abhijeet S. Barath ◽  
Juan M. Rojas Cabrera ◽  
Hojin Shin ◽  
...  
Keyword(s):  
Real Time ◽  
Closed Loop ◽  
Neurological Diseases ◽  
Pulse Frequency ◽  
Open Loop ◽  
Compulsive Disorder ◽  
Specific Disease ◽  
Disease States ◽  
Stimulation Parameters ◽  
The Individual

The development of closed-loop deep brain stimulation (DBS) systems represents a significant opportunity for innovation in the clinical application of neurostimulation therapies. Despite the highly dynamic nature of neurological diseases, open-loop DBS applications are incapable of modifying parameters in real time to react to fluctuations in disease states. Thus, current practice for the designation of stimulation parameters, such as duration, amplitude, and pulse frequency, is an algorithmic process. Ideal stimulation parameters are highly individualized and must reflect both the specific disease presentation and the unique pathophysiology presented by the individual. Stimulation parameters currently require a lengthy trial-and-error process to achieve the maximal therapeutic effect and can only be modified during clinical visits. The major impediment to the development of automated, adaptive closed-loop systems involves the selection of highly specific disease-related biomarkers to provide feedback for the stimulation platform. This review explores the disease relevance of neurochemical and electrophysiological biomarkers for the development of closed-loop neurostimulation technologies. Electrophysiological biomarkers, such as local field potentials, have been used to monitor disease states. Real-time measurement of neurochemical substances may be similarly useful for disease characterization. Thus, the introduction of measurable neurochemical analytes has significantly expanded biomarker options for feedback-sensitive neuromodulation systems. The potential use of biomarker monitoring to advance neurostimulation approaches for treatment of Parkinson’s disease, essential tremor, epilepsy, Tourette syndrome, obsessive-compulsive disorder, chronic pain, and depression is examined. Further, challenges and advances in the development of closed-loop neurostimulation technology are reviewed, as well as opportunities for next-generation closed-loop platforms.

Closing the loop

2011 ◽  
pp. 1869-1874
Author(s):  
Roman Hovorka
Keyword(s):  
Type 1 Diabetes ◽  
Real Time ◽  
Closed Loop ◽  
Insulin Delivery ◽  
Insulin Analogues ◽  
Open Loop ◽  
Subcutaneous Insulin ◽  
Closed Loop Systems ◽  
Acting Insulin

The standard therapy of type 1 diabetes is based on multiple daily injections of short- and long acting-insulin analogues accompanied by blood glucose self-monitoring. However, treatment goals identified by the Diabetes Control and Complications Trial are difficult to achieve due, at least in part, to a high risk of hypoglycaemia associated with many currents forms of intensive insulin therapy. Recent technological developments in real-time subcutaneous continuous glucose monitoring (CGM), combined with the continuous subcutaneous insulin infusion (CSII), could potentially reduce this risk. Since late 1990s at least five continuous or semicontinuous glucose monitors have received regulatory approval (1). CGM has been shown to improve glycaemic control in adults with type 1 diabetes, although apparent barriers to effectiveness in children and adolescents remain to be identified (see Chapter 13.4.9.1) (2). The availability of commercial CGM devices has reinvigorated research towards closed-loop systems (3-6), in which insulin is delivered according to real-time needs, as opposed to open-loop systems, which lack real-time responsiveness to changing glucose concentrations. Closed-loop insulin delivery, in which the insulin delivery is informed by the measured glucose concentrations has the potential gradually to revolutionize the management of type 1 diabetes by reducing or eliminating the risk of hypoglycaemia while achieving near-normal glucose levels. A closed-loop system, also called the ‘artificial pancreas’, comprises three components: a CGM device to measure real-time glucose concentration, a titrating algorithm to compute the amount of insulin needed, and an insulin pump delivering a rapid-acting insulin analogue (see Fig. 13.4.9.2.1). Only a few prototypes have been developed. Progress has been hindered by suboptimal accuracy and reliability of CGM devices, the relatively slow absorption of subcutaneously administered ‘rapid’-acting insulin analogues, and the lack of adequate control algorithms. So far, testing has been confined to the clinical setting. However, a concentrated effort promises an accelerated progress towards home testing of closed-loop systems. The research focus centres on systems utilizing subcutaneous glucose sensing and subcutaneous insulin delivery. This approach has the greatest potential for a near-future commercial exploitation, although other approaches utilizing intraperitoneal or intravenous sensing/delivery are, in principle, also feasible.

scholarly journals A new approach to railway track switch actuation: Dynamic simulation and control of a self-adjusting switch

2019 ◽  
Vol 234 (7) ◽  
pp. 779-790
Author(s):  
Saikat Dutta ◽  
Tim Harrison ◽  
Christopher Patrick Ward ◽  
Roger Dixon ◽  
Tara Scott
Keyword(s):  
Closed Loop ◽  
Dynamic Performance ◽  
Real Data ◽  
Open Loop ◽  
Railway Track ◽  
Railway Network ◽  
Loop Control ◽  
Novel Approach ◽  
Loop Feedback ◽  
And Control

The track switch is one of the key assets in any railway network. It is essential to allow trains to change route; however, when it fails, significant delays are almost inevitable. A relatively common fault is ‘loss of detection’, which can happen when there is a gradual track movement and the switch machines (actuators) no longer close the gap between the switch rail and stock rail to within safe tolerance levels. Currently, such misalignment is mitigated by a preventative programme of inspection and manual re-adjustment. In contrast to many other industries, the actuators are exclusively operated in open loop, with sensors (often limit switches) mainly being used for detection. Hence, an opportunity exists to investigate the closed loop control concepts for improving the operation of the switch. This paper proposes two advances: first, a novel approach is taken for modelling the dynamic performance of track switch actuators and the moving permanent-way components of the switch. The model is validated against real data from an operational switch. Secondly, the resulting dynamic model is then used to examine the implementation of closed loop feedback control as an integral part of track switch actuation. The proposed controller is found to perform well and offers the potential of ‘self-adjustment’, i.e. re-adjusting itself to close any gap (within a predefined range) between the stock and switch rails, thereby completing the switching operation.

Sign in / Sign up

Export Citation Format

Share Document