Emergency Stop Research Articles

Open Source Integrated Planner for Autonomous Navigation in Highly Dynamic Environments

Planning is one of the cornerstones of autonomous robot navigation. In this paper we introduce an open source planner called “OpenPlanner” for mobile robot navigation, composed of a global path planner, a behavior state generator and a local planner. OpenPlanner requires a map and a goal position to compute a global path and execute it while avoiding obstacles. It can also trigger behaviors, such as stopping at traffic lights. The global planner generates smooth, global paths to be used as a reference, after considering traffic costs annotated in the map. The local planner generates smooth, obstacle-free local trajectories which are used by a trajectory tracker to achieve low level control. The behavior state generator handles situations such as path tracking, object following, obstacle avoidance, emergency stopping, stopping at stop signs and traffic light negotiation. OpenPlanner is evaluated in simulation and field experimentation using a non-holonomic Ackerman steering-based mobile robot. Results from simulation and field experimentation indicate that OpenPlanner can generate global and local paths dynamically, navigate smoothly through a highly dynamic environments and operate reliably in real time. OpenPlanner has been implemented in the Autoware open source autonomous driving framework’s Robot Operating System (ROS).

Notfallkeratoplastik mit porcinen Xenotransplantaten bei nekrotisierender Keratitis

Background The great shortage of donor material in Ukraine makes it necessary to find additional sources of transplant material. A possible suitable material are the porcine corneas, as they are similar in structure and biomechanical parameters to the human cornea. The purpose of our study was to analyze the results of therapeutic keratoplasty (KP) with keratoxenotransplants from cryolyophilized porcine corneas in patients with severe necrotizing keratitis. Methods A retrospective analysis of 32 xenotransplantations patients with severe necrotizing keratitis (17 lamellar, 6stepped perforating, 4 perforating, 5 "biological coverage" according to Puchkovskaya) was completed. Results All eyes could be preserved, but the graft was rejected in all eyes. A semitransparent xenograft (XG) was achieved in 9 patients (33.3%). The best results were obtained after lamellar XKP with an XT diameter of 3.5 - 6.5 mm. Lamellar XTs with larger diameters (7.0 - 10.0 mm) were opaque. Postoperatively, the intensity of the inflammatory response after stepped XKP was slightly lower than that of the classical perforating XKP. A new KP with human corneas had to be performed in 5 patients, in one case combined with an antiglaucomatous operation and in another case with cataract extraction. Antiglaucomatous surgery had to be performed in 5 patients (15.6%). Conclusion In the absence of human donor corneas, a porcine keratoxenoimplant can be used as temporary therapeutic keratoplasty in case of emergency stop the inflammation process and to save the eye. In cases of keratoxenoimplant, a poor visual outcome is expected.

Dynamic modeling and finite element structural optimization of glass handling robot

PurposeThe purpose of this paper is to design a glass handling robot and conduct a finite element analysis and structural optimization to solve the automation handling problem of large-scale glass production line and aiming at the phenomenon that the vibration of robot manipulator may result in breakage of glass products, especially the fragile chemical or medical glassware. Making modal analysis for the robot is to determine its natural frequencies and vibration modes and lay a foundation for the transient analysis to study the vibration shock response of the robot during its start-up and emergency stop operation.Design/methodology/approachFirst, a 3D model of the robot is established according to the requirements of the production field and a finite element model is built on the basis of the 3D model. Then the modal and transient analyses of the robot are carried out according to the fact that the maximum vibration impact of the robot usually appears at the start and emergency stop.FindingsThe structure of the robot is improved according to the results of finite element analysis. The dynamic analysis results show that the improved robot’s ability to resist deformation under the impact of vibration shock is enhanced, and the robot can operate smoothly and meet the requirements of design in industrial environments.Originality/valueThe research results avoided the damage caused by the vibration and improved the service life of the robot, providing a foundation for the structural design and mass production of the glass handling robot.

Wind turbine control in computational fluid dynamics with OpenFOAM

In this article, the implementation of the pitch-control option is described within the OpenFOAM computational fluid dynamics library supported by the preliminary results for a few representative test cases. The proposed pitch-control logic represents a simplified version of the typically model available for the load simulation based on blade element momentum theory codes. The control variable for the blade pitch regulation is the rotor rotational speed, for which an additional torque-speed controller determining the equilibrium between the aerodynamic and the electrical torque is required. The simulations are performed on the 80-m-diameter turbine used as a reference design within the SmartBlades project. The unsteady test cases are based on the assumption of rigid, not pre-bend blade, and refer to an emergency stop and an extreme operating gust. Results verified the correctness of the implemented control logic and its sensitivity to the control parameters, that is, the key factors for a successful regulation of power production and load mitigation in wind turbine design. The implemented simulation methodology constitutes the first step toward the reproduction of very complex operating conditions for wind turbines by means of accurate computations.

A STUDY OF USING HYDROGEN GAS FOR STEAM BOILER IN CHOLOR– ALKALI MANUFACTURING

Main products of manufacturing of Cholor – Alkali, which commonly known as industrial chemical, are chlorine gas (Cl2), Sodium Hydroxide (NaOH) and hydrogen gas (H2). Chorine gas and sodium hydroxide are two main products for commercial profit; where hydrogen gas is by product. Most industries release hydrogen gas to atmosphere as it is non-profitable and less commercial scale. This study aims to make the most use of hydrogen as a substitute energy of natural gas for steam boiler to save energy cost. The second target of this study is to reduce level of CO2 release to air as a consequence of boiler combustion. This study suggests to install boiler that bases on hydrogen as main power with a high turndown ratio of at least 1:6. However, this case study uses boiler with two mode such as natural gas (NG) mode and mixed mode as they need to be flexible for production. Never the less, the best boiler selection is to use single mode energy of hydrogen. The most concerned issue about hydrogen gas is explosion during combustion stage. Stabilization measures at emergency stop is introduced to control H2 pressure to protect the explosion.This study varies ratio of natural gas to hydrogen gas to find the optimal level of two energy sources for boiler and measure total consumption through costing model; where CO2 level is measured at the boiler stack. The result of this study shows that hydrogen gas can be a substitute energy with natural gas and can reduce cost. Natural gas cost saving is 248,846 baht per month and reduce level of NOx is 80 ppm 7% O2 and 2 % of CO2 release to air as a consequence of boiler combustion.

Extremum-seeking algorithms for the emergency braking of heavy goods vehicles

A pneumatic slip control braking system was demonstrated, which reduces the emergency stopping distances of heavy goods vehicles by up to 19%. Solutions are still required to set the optimal reference wheel slip for this system online, so that it can adapt to changing operating conditions. This paper considers whether the use of extremum-seeking algorithms is a feasible alternative approach to online tyre model fitting, the computational expense of which has, to date, inhibited real-time implementation. The convergence and the stability properties of a first-order sliding-mode extremum-seeking algorithm are discussed, and its tuneable parameters are recast as physically meaningful performance metrics. Computer simulations are conducted using a detailed braking system model, and hardware-in-the-loop simulations are conducted with prototype pneumatic slip control braking hardware for heavy goods vehicles. The extremum-seeking algorithm enables the braking system to achieve at least 95% of the maximum possible braking force for almost the entirety of an emergency stop. The robustness to parameter errors, the road roughness and the changing friction conditions are all explored.

Combined emergency braking and turning of articulated heavy vehicles

ABSTRACT‘Slip control’ braking has been shown to reduce the emergency stopping distance of an experimental heavy goods vehicle by up to 19%, compared to conventional electronic/anti-lock braking systems (EBS). However, little regard has been given to the impact of slip control braking on the vehicle’s directional dynamics. This paper uses validated computer models to show that slip control could severely degrade directional performance during emergency braking. A modified slip control strategy, ‘attenuated slip demand’ (ASD) control, is proposed in order to rectify this. Results from simulations of vehicle performance are presented for combined braking and cornering manoeuvres with EBS and slip control braking with and without ASD control. The ASD controller enables slip control braking to provide directional performance comparable with conventional EBS while maintaining a substantial stopping distance advantage. The controller is easily tuned to work across a wide range of different operating conditions.

Development of Emergency Stop Device for Hand-Fed Threshing on Head-Feeding Combine (Part 2)

Development of Emergency Stop Device for Hand-Fed Threshing on Head-Feeding Combine (Part 2)

MR流体ダンパを取り入れた新構成エレベータ非常止め装置の基礎検証

MR流体ダンパを取り入れた新構成エレベータ非常止め装置の基礎検証

A practical soil-structure interaction model for a wind turbine subjected to seismic loads and emergency shutdown

In seismically active areas the design of wind turbine must be verified for seismic load combinations. These consider a certain likelihood of earthquake occurrence during normal operation, which could eventually lead to an emergency stop. In order to simulate these scenarios, the computational model should take into account the aerodynamics of the rotor, the flexibility of tower and soil, transient operational phases and, first and foremost, the interrelation of all these aspects. At the same time, the complexity should be reduced in order to avoid enormous computational costs, especially when the soil-structure interaction is taken into account. This study presents a practical model for the analysis of the soil-structure interaction effects on the seismic behavior of wind turbine, during normal power production and emergency shutdown. The presented model is based on simplified lumped parameter model for the soil-foundation subsystem and is validated against a detailed model, based on a 3D coupled finite element method and scaled boundary finite element method approach. This article shows a demonstrative example for a reference 5MW wind turbine subjected to a seismic event which triggers an emergency shutdown. The application of the lumped parameter model allows a significant model size reduction and accurate approximation of the soil-structure behavior in time domain.

Neural Network as an Alternative to the Amplitude Spectrum Analysis for Measurement of the Ball Mill Fill Level

Modern intelligent methods for information processing are used to estimate the filling level of the ball mills. This problem has been topical for a long time. Moreover, the increasing number of the used ball mills makes it even more important. The main objective is that the ball mill's functioning mode, which is optimal from the point of view of the energy efficiency, can be reached, if the mill is loaded with the ore as much as possible. In its turn, such a mode may cause an overloading in case of any additional ore supply. This leads to the balls' and ore grain's coarse blowout and, as a result, the mill emergency stopping. As a consequence, the mill downtime results in economic losses. The main aim of this research is to develop a method for processing of the vibration acceleration signal from the ball mill's pin in order to discover the hidden dependencies in it. Such dependencies will allow us to estimate the mills' filling level more effectively, but they cannot be discovered by the classical methods, like spectrum analysis of the signal amplitude. A pilot ball mill is used in the laboratory conditions in order to reach such results. A vibration acceleration sensor is set at its pin. A ball load is changed during experiments. A training set for a neural network is formed as a result of the spectrum analysis of the signal obtained from the sensor. The neural network helped to find a relation between the vibration acceleration spectrum and the ball mill filling level. After the conducted experiments a conclusion can be made that such a network is insensitive to the noise caused by a change of the ball load. This insensitivity is higher in comparison with the methods, which are used as a basis for the conventional vibration-acoustic analyzers.

Influence of Prior Cervical Surgery on Surgical Outcome of Endoscopic Posterior Cervical Foraminotomy for Osseous Foraminal Stenosis

Posterior cervical foraminotomy is a valuable option as a treatment for cervical radiculopathy caused by osseous foraminal stenosis. Here the authors present their technique and results in a series of patients with and without previous surgery. Forty-five patients suffering from cervical osseous foraminal stenosis were operated on via a microendoscopic posterior approach with the EasyGO system. All procedures were video recorded and afterwards retrospectively analyzed. The primary evaluation criterion was prior surgery or no prior surgery. Additionally, postoperative outcome according to Odom's criteria and Neck Disability Index (NDI), reoperation rate, and complications was considered. The 45 patients of this study showed an overall clinical success rate of 84%. There was no emergency stopping of any endoscopic procedure. Twenty patients (44.4%) had no and 25 patients (55.6%) had previous cervical surgery. In patients without previous surgery, the clinical success rate was 95.2%; NDI was 12%; and 100% of patients reported reduction of their preoperative arm pain and motor recovery. In patients with previous surgery, the clinical success rate was 75%. NDI was 24%. Most patients (91.7%) reported reduction of their preoperative arm pain, and 66.7% reported recovery of motor strength. This retrospective analysis shows that microendoscopic posterior cervical foraminotomy is a successful option in the treatment of osseous cervical foraminal stenosis. Nevertheless, clinical success in patients with previous surgery is much lower compared with patients without previous surgery. Thus, a more thorough clinical workup is recommended to identify the patients who are not going to benefit before subsequent surgical procedures.

Ultimate design load analysis of planetary gearbox bearings under extreme events

AbstractThis paper investigates the impact of extreme events on the planet bearings of a 5 MW gearbox. The system is simulated using an aeroelastic tool, where the turbine structure is modeled, and MATLAB/Simulink, where the drivetrain (gearbox and generator) are modeled using a lumped‐parameter approach. Three extreme events are assessed: low‐voltage ride through, emergency stop and normal stop. The analysis is focused on finding which event has the most negative impact on the bearing extreme radial loads. The two latter events are carried out following the guidelines of the International Electrotechnical Commission standard 61400‐1. The former is carried out by applying a voltage fault while simulating the wind turbine under normal turbulent wind conditions. The voltage faults are defined by following the guidelines from four different grid codes in order to assess the impact on the bearings. The results show that the grid code specifications have a dominant role in the maximum loads achieved by the bearings during a low‐voltage ride through. Moreover, the emergency brake shows the highest impact by increasing the bearing loads up to three times the rated value. Copyright © 2016 John Wiley & Sons, Ltd.

Sixty years of research on ship rudders: effects of design choices on rudder performance

ABSTRACTRudders are primary steering devices for merchant ships. The main purpose of using rudders is to generate forces for course keeping and manoeuvring. In exceptional cases, rudders are also used for emergency stopping and roll stabilisation. Furthermore, rudders affect propeller thrust efficiency and total ship resistance. Therefore, rudders are important to navigation safety and transport efficiency. The performance of rudders depends on the rudder hydrodynamic characteristics, which are affected by the design choices. Scholarly articles concerning the design of rudders date back more than 60 years. Moreover, a lot of knowledge fragments of rudders exist in literature where ship manoeuvrability and fuel consumption are discussed. It is worthwhile to gather this information not only for researchers to advance the state-of-the-art development but also for designers to make proper choices. To have a contemporary vision of the rudders, this paper presents a consolidated review of design impacts on rudder performance in ship manoeuvrability, fuel consumption, and cavitation. The discussed design choices are rudder working conditions (Reynolds numbers and angles of attack), profiles (sectional shapes), properties (area, thickness, span, chord, and rudder aspect ratios), types (the position of the stock and the structural rudder–hull connection), and interactions (among the hull, the propeller, and the rudder). Further research is suggested on high-lift rudder profiles, multiple-rudder configurations and interactions among the hull, the propeller, and the rudder. Recommendations for industry practices in the selection of the rudder design choices are also given.

Endoscopic Posterior Cervical Foraminotomy as a Treatment for Osseous Foraminal Stenosis

Posterior cervical foraminotomy is a valuable treatment option for cervical radiculopathy. Here the authors present their technique and results in the treatment of a series of patients suffering from osseous foraminal stenosis. Forty-three patients suffering from cervical osseous foraminal stenosis were operated on via a posterior approach with the EasyGO endoscopic system. Decompression was performed in 1 segment in 31 patients, in 2 segments in 11 patients, and in 3 segments in 1 patient. Bilateral decompression was performed in 4 cases. Twenty-four (55.8%) patients had been subjected to previous spine surgery. All procedures were video recorded and afterwards retrospectively analyzed. In addition, particular reference was given to previous cervical spine surgery, postoperative outcome, reoperation rate, and complications. The endoscopic system was easy to handle intraoperatively in all procedures. No emergency stopping was required. Forty-one patients reported improved and/or even no remaining pain postoperatively (95%). Thirty-five patients (81.4%) regained full motor strength. Clinical success rate with respect to Odom's criteria reached 39 patients (90.7%). One reoperation was needed due to postoperative hematoma (2.3%). One patient suffered from transient worsening of his preoperative paresis (2.3%). Neither dural tear nor nerve root injury was observed. Reoperation rate due to degenerative changes was 18.6% (8of 43 patients). This retrospective analysis shows that posterior endoscopic decompression is a successful option in the treatment of osseous cervical foraminal stenosis.

Root cause analysis of the folding deformation for the expansion joint in the nuclear power station

In the nuclear power station, the expansion joint of moisture separator re-heater (MSR for short) was founded locally folding deformation under the outage condition. Folding deformation increasing will lead expansion joint leak, it would cause emergency stop when leaking seriously. To solve these problems, this paper analysis mainly on three aspects: the material organization performance, the expansion joint installation and the stress characteristic of expansion joint. Both the verticality deviation in the process of installation and the material hardness value exceed standard are the root cause of these problems. At the end of the paper, the improvements have been put forward for this problem.

How to Protect the Tunnel SOS Niche Wall in the Event of Vehicle Impact

An increase in the number of traffic accidents in tunnel emergency stop areas has been recored in the last two years in many countries with long road tunnels. In most cases, the collisions of passenger cars into the emergency stop area walls were fatal, which presents an even bigger obligation for the road management authorities to find a solution to the problem. Even though the tunnel emergency stop areas tunnels are designed and built according to the valid legislation, it has turned out that the current implementation of the emergency stop area wall in the driving direction presents a serious potential traffic safety risk.With the purpose of determining the most suitable method of protecting the SOS tunnel niche wall in the event of vehicle impacts, comparative numerical analysis of vehicle impacts has been performed in accordance with the SIS – EN 1317 standard. For the emergency-stop-area wall-impact protection, two different designs were considered: the H2 safety railing and the crash cushion composed of eight cylindrical steel sheet tubes. The tube diameter is 500mm and the sheet thickness is 3mm. Both designs were subject to collision simulations in accordance with EN 1317 parts 1 and 2 (EN 1317-1 – -4). As the safety of passenger cars was being studied, the tests TB 11 (vehicle mass 900kg and vehicle velocity 100km/h) and TB 21 (vehicle mass 1300kg and vehicle velocity 80km/h were simulated with a finite-element-model-based explicit dynamic analysis. The kinematic values of the vehicles just prior to the collision were determined by simulating the driving dynamics several seconds before the collision in PC-Crash. Based on the FEM analysis results in LS-Dyna for each crash scenario, a comparative analysis of the two protection systems was performed in order to determine their efficiency and suitability for installation in the existing tunnel emergency stop areas.Based on comparative analyses of the values of the Acceleration Severity Index (ASI), Theoretical Head Impact Velocity (THIV) and values of the Post-Impact Head Deceleration (PHD), the crash cushion provides the best results for the events of impacts of TB 11 vehicles and TB 21 vehicles into an SOS tunnel niche.

Estimating Project-Level Vehicle Emissions with Vissim and MOVES-Matrix

Estimating transportation network emissions requires multiplying estimates of on-road vehicle activity (by source type and operating mode) by applicable emission rates for the observed source type and operating conditions. Coupling microsimulation model runs with emissions modeling can make fast assessments possible in transportation air quality planning. This research developed a tool with automated linkage between the Vissim microsimulation model and the Motor Vehicle Emission Simulator (MOVES) model. To link the two models, the research team used MOVES-Matrix, which was prepared by iteratively running MOVES across all possible iterations of vehicle source type, fuel, environmental and operating conditions, and other parameters (hundreds of millions of model runs) to create a multidimensional emission rate lookup matrix. A Vissim simulation of the major arterial roads and freeways at I-85 and Jimmy Carter Boulevard in Gwinnett County, Georgia, provided the case study for this MOVES-matrix application. The researchers present predicted emissions and the results of a sensitivity analysis to identify the potential impacts of various internal Vissim modeling parameters (such as minimum headway, maximum deceleration rate for cooperative braking, and emergency stop distance) on a case study’s emissions outputs. The sensitivity analysis found that internal Vissim parameters impacted emissions and that proper care should be taken in using Vissim for emissions analysis at the corridor and link level. The case study demonstrates that Vissim coupled with MOVES-Matrix can be an effective tool for emissions analysis.

Study on the status of the working bodies grinding machines based on vibration analysis

Improvement of technology and engineering aimed at the use of secondary raw material is an important task. One of the most important operations in the preparation of raw materials for mixed feeds is fine grinding. In this regard, the article discusses the grinding equipment allowing to obtain raw materials of higher quality with the lower energy consumption. Methods and diagnostic tools were proposed, the principle of determining the locations (points) of installation of vibration measurement sensors as well as the choice of the vibration signal analysis method were considered. Investigation of the state of the disintegrator working bodies was carried out in the workshop of LLC PСF Luch 2000. The object of study is a disintegrator with rotors diameter of 350 mm, each of them having two rows of pins. The result of the experiment revealed that during the operation the working bodies of grinding machines are exposed to uneven wear and under the action of multicycle load micro-cracks and fatigue fractures occur. The method of spectral analysis revealed the appearance of harmonics with large vibration at a frequency of 126 Hz, as well as multiple frequencies, allowing a high degre e of probability to determine not only the actual state of the working bodies, but also to predict the defect development trend. Based on the analysis of the spectra, the decision on further time operation of the equipment is made, which significantly reduces the probability of an emergency stop of equipment and expensive repairs. The research data will be relevant when using vibration diagnostics tools in enterprises, as well as in the design, construction and choice of materials for grinding equipment.

迅速性と確実性を考慮した非常停止ボタンの最適配置の検討

迅速性と確実性を考慮した非常停止ボタンの最適配置の検討