Features of using azipods as main propulsion components for conning and maneuvering the modern arctic LNG gas carriers. Emergency stop simulation

A small general-purpose teleoperated hydraulic mobile machine is studied at the Institute of Hydraulics and Automation at the Tampere University of Technology. Thanks to teleoperation, the operator of the machine is able to be in safe place during the driving when necessary. However, the actions of the machine can be dangerous for the people or the objects in the environment if problems appear for instance in the control system. On that account, safety issues must be considered carefully. Special attention has to be paid to stop the machine and start the engine again once the machine has recovered from an error situation. The goal of this paper is to describe the design and implementation of different kind of solutions to start and stop the machine wirelessly. The emergency stop can be activated through the wireless connection by the operator or by the automatic diagnostic system of the hydraulic mobile machine. The control system monitors the state of several hydraulic components such as hydraulic valves and motors by means of sensors during the operations of machine. The machine is teleoperated by using WLAN (Wireless Local Area Network) connection. The developed wireless starting system and emergency stop is totally independent of the WLAN link. In the first prototype of the wireless starting system and emergency stop, the wireless connection is carried out by using commercial, cost effective RF (Radio Frequency) modules. The data transfer protocol which is used by the modules is designed for this application. Protocol implementation is carried out with microcontrollers. Another version of the wireless starting system and emergency stop is carried out by using radio modems. The modems have better properties than the cost effective RF modules used in the first prototype due to their higher RF output power. Programmatically carried out automatic emergency stop, which stops the machine, if the WLAN connection between the control station and the machine breaks, is discussed. In that case, the independent wireless emergency stop connection is not needed. Implementations of the system are introduced in this paper. Also, some testing results and user experiences are described. Properties of these different implementations are compared: cost of the system, range, reliability and complexity of the implementation. By means of the studied results the most suitable solution to start the engine and stop the actions of the machine is chosen.

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Reactive power characteristics analysis on emergency stop of doubly fed induction generator

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/383/1/012058 ◽

2018 ◽

Vol 383 ◽

pp. 012058

Author(s):

Yuting Zhao ◽

Yang Cui ◽

Yaohua Tang ◽

Weimin Guo

Keyword(s):

Reactive Power ◽

Induction Generator ◽

Doubly Fed Induction Generator ◽

Power Characteristics ◽

Characteristics Analysis ◽

Emergency Stop ◽

Doubly Fed

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Influence of Left- and Right-Side Total Hip Arthroplasty on the Ability to Perform an Emergency Stop While Driving a Car

Archives of Physical Medicine and Rehabilitation ◽

10.1016/j.apmr.2014.03.009 ◽

2014 ◽

Vol 95 (9) ◽

pp. 1702-1709 ◽

Cited By ~ 15

Author(s):

Maurice Jordan ◽

Ulf Krister Hofmann ◽

Julia Grünwald ◽

Morten Meyer ◽

Saskia Sachsenmaier ◽

...

Keyword(s):

Total Hip Arthroplasty ◽

Hip Arthroplasty ◽

Total Hip ◽

Left And Right ◽

Emergency Stop

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Detailed Analyses of the Tow Line Behaviour in Single, Double and Triple Towages in Case of Emergency Stop and Catenary

Volume 1: Offshore Technology; Polar and Arctic Sciences and Technology ◽

10.1115/omae2011-50327 ◽

2011 ◽

Author(s):

A. J. Bos ◽

R. Heemskerk

Keyword(s):

Element Model ◽

Numerical Approach ◽

Stopping Distance ◽

Contingency Plans ◽

Safe Side ◽

Emergency Stop ◽

The Wire ◽

Engine Failure ◽

The Moment ◽

Model Approach

Two phenomena have been studied in order to enhance the contingency plans and improve the safety of towages. 1. For multi tug towages it is important to prepare proper contingency plans for the case that a tug fails and overrun by the tow is a probability, especially the towages of FPSO’s and huge rigs performed by more tugs. A model has been developed to assess the time between the failure and the moment the tow will collide. After thorough research not the stopping distance proved important, but the time it takes for both objects to collide. In case the tug is allowed to be pulled towards the FPSO, the time from engine failure to collision is 380 [s] or 6 minutes 20 seconds. Both objects will collide with a speed difference of 2.28 [m/s]. In case the towline is cut, the time until collision is 1479 [s], or 24 minutes and 40 seconds. In this case it is very important to cut the towline instantly after the engine failure. Otherwise the tug will gain a negative speed of 1 m/s within 2 minutes, and the distance between the FPSO and the tug will be reduced to 683 [m] already. 2. Grounding of tow lines must be avoided the standard of the catenary approach to assume a hyperbolic shape is investigated and a detailed finite element model approach shows that the standard assumptions are not accurate enough. A numerical approach has been used to calculate the effect of current and loss of tension in the wire. The influence of current along the towing-wire depends on the speed, diameter, length and the angle of the towing-wire in the water. The maximum depth increases when the speed increases or the tension in the wire decreases. In the example the depths are on the safe side for depths below 35[m], but above 35[m] the values are too optimistic when current is involved.

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INTRODUCING SITETRACK

Neurosurgery ◽

10.1227/01.neu.0000340794.30989.8c ◽

2009 ◽

Vol 64 (suppl_2) ◽

pp. A110-A122 ◽

Cited By ~ 6

Author(s):

Kenichi Saito ◽

Masami Fujii ◽

Koji Kajiwara ◽

Michiyasu Suzuki

Keyword(s):

Regression Analysis ◽

Stereotactic Radiotherapy ◽

Head Movement ◽

Target Localization ◽

Mean Square ◽

Localization System ◽

System Parameters ◽

Thermoplastic Mask ◽

Emergency Stop ◽

The Moment

Abstract OBJECTIVE Immobilization of the head during stereotactic radiotherapy (STR) has, until recently, been fundamental for ensuring accuracy. We developed a continuous motion monitoring system (SiteTrack) to detect and quantify head movement during CyberKnife (Accuray, Inc., Sunnyvale, CA) STR and Leksell (Elekta AB, Stockholm, Sweden) frame fixation. In this study, we present findings obtained during tests of SiteTrack. METHODS SiteTrack is composed of a potentiometer with 4 encoders connected through 4 threads tied to the plastic buttons attached to the thermoplastic mask, in the case of CyberKnife, or by 3 threads directly connected to the Leksell frame. The accuracy of SiteTrack was studied with a phantom using the target localization system of the CyberKnife. During CyberKnife treatment, SiteTrack software sends an emergency stop signal (E-stop) if the patient moves beyond a limit. Seventy-three cases of CyberKnife STR and 7 cases of Leksell frame fixation were monitored. RESULTS In the phantom study, regression analysis showed a significant correlation between SiteTrack and target localization system parameters. The expected root mean square position error at the moment of E-stop was 0.62 ± 0.44 mm when the E-stop limit was set at ±0.5 mm. Twenty-two (30%) of 73 patients kept still during CyberKnife treatment (<0.5 mm); 51 (70%) of 73 patients moved more than 0.5 mm and, thus, caused E-stops. SiteTrack monitoring during frame fixation showed motion beyond ±1 mm in 4 cases and ±0.5 mm in 3 other cases. CONCLUSION Significant head movement can occur during CyberKnife treatment or fixation with a Leksell frame. SiteTrack may improve the accuracy of the CyberKnife as well as frame-based STR.

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Evaluation of Human Pain Tolerance and Its Application to Designing Safety Robot Mechanisms for Human-Robot Coexistence

Journal of Robotics and Mechatronics ◽

10.20965/jrm.1997.p0065 ◽

1997 ◽

Vol 9 (1) ◽

pp. 65-70 ◽

Cited By ~ 7

Author(s):

Yoji Yamada ◽

Keyword(s):

Pain Tolerance ◽

Tolerance Limit ◽

Contact Forces ◽

Normal Operation ◽

Robot System ◽

Speed Reduction ◽

Emergency Stop ◽

Contact Sensing ◽

Fail Safe

This paper describes, with reference to related studies, a human-oriented design approach to developing a safe robot system for human-robot coexistence. First, a soft covering made of a visco-elastic material is designed to achieve both effective impact force attenuation and high contact sensitivity within a human pain tolerance limit. Second, a fail-safe robot system is constructed with contact sensing and subsequent emergency stop control capabilities, primarily by using a simple disturbance observer which plays an important role of checking the normal operation of a two-link DD-motor-driven manipulator. Actual human-robot collision experiments verified that the contact forces generated at the collisions were suppressed below the human pain tolerance limit. Moreover, an additional robot speed reduction mechanism was provided to show that the human reflexive motions to avoid a severe contact with the robot within a safeguarding space contribute to enhancing the efficiency of the system to the point of reducing the speed of the robot in a safe manner when the robot comes in contact with the human.

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