Forces in rotary motion systems

2008 ◽  
Author(s):  
Markus K. Tilsch ◽  
Gregory K. Elliott
Keyword(s):  
Rotary Motion

Problem of angular motion control of a non-cooperative on-orbit service object

2021 ◽  
Vol 2021 (1) ◽  
pp. 37-50
Author(s):  
A.A. Fokov ◽  
◽  
O.P. Savchuk ◽  
Keyword(s):  
Motion Control ◽  
State Of The Art ◽  
Object Motion ◽  
The State ◽  
Angular Motion ◽  
Motion Parameter ◽  
Rotary Motion ◽  
Parameter Determination ◽  
Service Object

The realization of existing projects of on-orbit servicing and the development of new ones is a steady trend in the development of space technology. In many cases, on-orbit service clients are objects that exhibit an undesired rotary motion, which renders their servicing difficult or impossible. The problem of on-orbit service object motion control determines the topicality of studies aimed not only at the refinement of methods and algorithms of controlling both the translational and the rotary motion of an object, but also at the development and refinement of methods of onboard determination of the object – service spacecraft relative motion parameters. This paper overviews the state of the art of the problem of object motion parameter determination in on-orbit servicing tasks and existing methods of object motion control and angular motion damping and specifies lines of further investigations into the angular motion control of non-cooperative service objects. Based on the analysis of publications on the subject, the applicability of onboard means for object motion parameter determination is characterized. The analysis of the applicability of methods of remote determination of the parameters of an unknown non-cooperative object from a service spacecraft shows that they are at the research stage. The input data for the verification of methods proposed in the literature were simulated or taken from ground experiments or previous missions. Contact and contactless methods of angular motion control of non-cooperative on-orbit service objects are considered. From the state of the art of investigations into the contactless motion control of on-orbit service objects it may be concluded that the most advanced contactless method of motion control of an on-orbit service object is a technology based on the use of an ion beam directed to the object from an electrojet engine onboard a service spacecraft. Lines of further investigations into non-cooperative object motion control are proposed.

Posterior Temporary C1-2 Pedicle Screws Fixation for the Treatment of Unstable C1-2 Complex Fractures: Minimum of 2-Year Follow-Up

2021 ◽  
pp. 219256822110391
Author(s):  
Yakubu Ibrahim ◽  
Hao Li ◽  
Geng Zhao ◽  
Suomao Yuan ◽  
Yiwei Zhao ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Internal Fixation ◽  
Neck Disability Index ◽  
Pedicle Screws ◽  
Rotary Motion ◽  
Upper Cervical Spine ◽  
Complex Fractures ◽  
Upper Cervical ◽  
Better Than

Study Design: Retrospective. Objectives: To present rarely reported complex fractures of the upper cervical spine (C1-C2) and discuss the clinical results of the posterior temporary C1-2 pedicle screws fixation for C1-C2 stabilization. Methods: A total of 19 patients were included in the study (18 males and 1 female). Their age ranged from 23 to 66 years (mean age of 39.6 years). The patients were diagnosed with complex fractures of the atlas and the axis of the upper cervical spine and underwent posterior temporary C1-2 pedicle screws fixation. The patients underwent a serial postoperative clinical examination at approximately 3, 6, 9 months, and annually thereafter. The neck disability index (NDI) and the range of neck rotary motion were used to evaluate the postoperative clinical efficacy of the patients. Results: The average operation time and blood loss were 110 ± 25 min and 50 ± 12 ml, respectively. The mean follow-up was 38 ± 11 months (range 22 to 60 months). The neck rotary motion before removal, immediately after removal, and the last follow-up were 68.7 ± 7.1°, 115.1 ± 11.7°, and 149.3 ± 8.9° ( P < 0.01). The NDI scores before and after the operation were 42.7 ± 4.3, 11.1 ± 4.0 ( P < 0.01), and the NDI score 2 days after the internal fixation was removed was 7.3 ± 2.9, which was better than immediately after the operation ( P < 0.01), and 2 years after the internal fixation was removed. The NDI score was 2.0 ± 0.8, which was significantly better than 2 days after the internal fixation was taken out ( P < 0.001). Conclusions: Posterior temporary screw fixation is a good alternative surgical treatment for unstable C1-C2 complex fractures.

Stimulus-responsive molecular rotors: Control of rotary motion in triptycene–ionophore systems with s-block metal cations

2008 ◽  
Vol 517 (4) ◽  
pp. 1428-1433 ◽  
Author(s):  
Osamu Tsutsumi ◽  
Fumiko Suzuki ◽  
Mai Oowaki ◽  
Yoshie Okazaki ◽  
Kazuyoshi Takeda ◽  
...  
Keyword(s):  
Metal Cations ◽  
Molecular Rotors ◽  
Rotary Motion ◽  
Stimulus Responsive

Study on Twin-Rotary Motion Control System Based on Siemens Technology CPU

2012 ◽  
Vol 229-231 ◽  
pp. 2201-2204
Author(s):  
Cun Hai Pan ◽  
Hui Li ◽  
Su Mei Du ◽  
Wei Gao
Keyword(s):  
Control System ◽  
Motion Control ◽  
Rotary Motion ◽  
Three Dimension ◽  
Motion Control System ◽  
Loop Control ◽  
Closed Loop Control System ◽  
Loop Control System ◽  
Dimension Space ◽  
The Cost

A twin-rotary motion control system was built based on a cam technology and Siemens S7-300T PLC in this paper. The system can position accurately in a three-dimension space using a twin-servo closed loop control system and can real-time monitor various parameters of positioning system by HMI (Human Machine Interface). It also can automatically collect various parameter information and judge the type of fault.At the same time, the degree of automation has been raised and the cost of production was reduced.

scholarly journals Basics of the electropiezoelasticity theory of piezoelectric motors with linear and rotary motion

2018 ◽  
Vol 67 (4) ◽  
pp. 149-168
Author(s):  
Włodzimierz Przyborowski
Keyword(s):  
Piezoelectric Effect ◽  
Rotary Motion ◽  
Electric Motors ◽  
Motion Equations ◽  
Piezoelectric Motors ◽  
Rotary Motors ◽  
General Mathematical Model ◽  
Linear Movement ◽  
Single Field ◽  
Constitutive Parameters

The paper presents the basics of the theory of electropiezoelasticity and adaptation of this theory to description of the simplest electromechanical converters − piezoelectric type electric motors. Because piezoelectricity and elasticity are coupled by complex piezoelasticity constitutive compounds, the formulation of a general mathematical model for these motors is not possible. Therefore, equations for structurally simple piezoelectric motors with linear and rotational motion have been formulated in the paper. Motors with linear movement are characterized by a flat or tube form. Rotary motors, on the other hand, have a cylindrical or disc-shaped form. The electric field, in the adopted forms of piezoelectric motors generating a piezoelectric effect, is a single-field perpendicular to the direction of motion. The determined equations could be simplified by reduction of some constitutive parameters, but it requires a detailed analysis of material compounds and consideration in the interactions of forces and torques in these motors, also strong piezoelectric stresses, which determine a specific kinetics. Keywords: piezoelectric motors with translational and rotary motion, equations of electric-piezoelasticity.

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