Calibration of Parallel Kinematic Machine Based on Stewart Platform – A Literature Review

2021 ◽  
Author(s):  
Sourabh Karmakar ◽  
Apurva Patel ◽  
Cameron J. Turner
Keyword(s):  
Movement Control ◽  
Specific Area ◽  
Stewart Platform ◽  
Inverse Kinematic ◽  
Multiple Sources ◽  
Error Sources ◽  
Automobile Manufacturing ◽  
3D Space ◽  
Current State ◽  
Parallel Kinematic

Abstract Stewart platform-based Parallel Kinematic Machines (PKM) have been extensively studied by researchers due to their inherent finer control characteristics. This has opened its potential deployment opportunities in versatile critical applications like the medical field, engineering machines, space research, electronic chip manufacturing, automobile manufacturing, etc. All these precise, complicated, and repeatable motion applications require micro and nano-scale movement control in 3D space; a 6-DOF PKM can take this challenge smartly. For this, the PKM must be more accurate than the desired application accuracy level and thus proper calibration for a PKM robot is essential. Forward kinematics-based calibration for such hexapod machines becomes unnecessarily complex and inverse kinematics complete this task with much ease. To analyze different techniques, an external instrument-based, constraint-based, and auto or self-calibration-based approaches have been used for calibration. This survey has been done by reviewing these key methodologies, their outcome, and important points related to inverse kinematic-based PKM calibrations in general. It is observed in this study that the researchers focused on improving the accuracy of the platform position and orientation considering the errors contributed by a single source or multiple sources. The error sources considered are mainly structural, in some cases, environmental factors are also considered, however, these calibrations are done under no-load conditions. This study aims to understand the current state of the art in this field and to expand the scope for other researchers in further exploration in a specific area.

scholarly journals CAR-NK Cells in the Treatment of Solid Tumors

2021 ◽  
Vol 22 (11) ◽  
pp. 5899
Author(s):  
Ewa Wrona ◽  
Maciej Borowiec ◽  
Piotr Potemski
Keyword(s):  
Nk Cells ◽  
Solid Tumors ◽  
Hematological Malignancies ◽  
Toxicity Profile ◽  
Multiple Sources ◽  
Eligibility Criteria ◽  
Hematological Neoplasms ◽  
Current State ◽  
Car T ◽  
The Cost

CAR-T (chimeric antigen receptor T) cells have emerged as a milestone in the treatment of patients with refractory B-cell neoplasms. However, despite having unprecedented efficacy against hematological malignancies, the treatment is far from flawless. Its greatest drawbacks arise from a challenging and expensive production process, strict patient eligibility criteria and serious toxicity profile. One possible solution, supported by robust research, is the replacement of T lymphocytes with NK cells for CAR expression. NK cells seem to be an attractive vehicle for CAR expression as they can be derived from multiple sources and safely infused regardless of donor–patient matching, which greatly reduces the cost of the treatment. CAR-NK cells are known to be effective against hematological malignancies, and a growing number of preclinical findings indicate that they have activity against non-hematological neoplasms. Here, we present a thorough overview of the current state of knowledge regarding the use of CAR-NK cells in treating various solid tumors.

ARESIBO HORIZON 2020 EUROPEAN RESEARCH PROJECT – ENRICHED SITUATION AWARENESS FOR BORDER SURVEILLANCE

2021 ◽  
Vol 17 (1) ◽  
pp. 247-255
Author(s):  
Konstantinos CHARISI ◽  
Andreas TSIGOPOULOS ◽  
Spyridon KINTZIOS ◽  
Vassilis PAPATAXIARHIS
Keyword(s):  
Augmented Reality ◽  
Situation Awareness ◽  
User Interfaces ◽  
Border Security ◽  
Multiple Sources ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
Current State ◽  
Available Information ◽  
User Friendly

Abstract. The paper aims to introduce the ARESIBO project to a greater but targeted audience and outline its main scope and achievements. ARESIBO stands for “Augmented Reality Enriched Situation awareness for Border security”. In the recent years, border security has become one of the highest political priorities in EU and needs the support of every Member State. ARESIBO project is developed under HORIZON 2020 EC Research and Innovation program and it is the joint effort of 20 participant entities from 11 countries. Scientific excellence and technological innovation are top priorities as ARESIBO enhances the current state-of-the-art through technological breakthroughs in Mobile Augmented Reality and Wearables, Robust and Secure Telecommunications, Robots swarming technique and Planning of Context-Aware Autonomous Missions, and Artificial Intelligence (AI), in order to implement user-friendly tools for border and coast guards. The system aims to improve the cognitive capabilities and the perception of border guards through intuitive user interfaces that will help them acquire an improved situation awareness by filtering the huge amount of available information from multiple sources. Ultimately, it will help them respond faster and more effectively when a critical situation occurs.

scholarly journals About uncertainties in practical salinity calculations

Ocean Science ◽  
2011 ◽  
Vol 7 (5) ◽  
pp. 651-659 ◽  
Author(s):  
M. Le Menn
Keyword(s):  
State Of The Art ◽  
Conductivity Ratio ◽  
Real Analysis ◽  
Error Sources ◽  
Current State ◽  
Laboratory Calibration ◽  
Temperature And Pressure ◽  
Conductivity Cell ◽  
Temperature Depth

Abstract. In the current state of the art, salinity is a quantity computed from conductivity ratio measurements, with temperature and pressure known at the time of the measurement, and using the Practical Salinity Scale algorithm of 1978 (PSS-78). This calculation gives practical salinity values S. The uncertainty expected in PSS-78 values is ±0.002, but no details have ever been given on the method used to work out this uncertainty, and the error sources to include in this calculation. Following a guide published by the Bureau International des Poids et Mesures (BIPM), using two independent methods, this paper assesses the uncertainties of salinity values obtained from a laboratory salinometer and Conductivity-Temperature-Depth (CTD) measurements after laboratory calibration of a conductivity cell. The results show that the part due to the PSS-78 relations fits is sometimes as significant as the instrument's. This is particularly the case with CTD measurements where correlations between variables contribute mainly to decreasing the uncertainty of S, even when expanded uncertainties of conductivity cell calibrations are for the most part in the order of 0.002 mS cm−1. The relations given here, and obtained with the normalized GUM method, allow a real analysis of the uncertainties' sources and they can be used in a more general way, with instruments having different specifications.

scholarly journals Climate-dependent propagation of precipitation uncertainty into the water cycle

2020 ◽  
Author(s):  
Ali Fallah ◽  
Sungmin O ◽  
Rene Orth
Keyword(s):  
Hydrological Model ◽  
Water Cycle ◽  
State Of The Art ◽  
Rain Gauge ◽  
Multiple Sources ◽  
Current State ◽  
Wide Range ◽  
The Impact ◽  
Conceptual Hydrological Model

Abstract. Precipitation is a crucial variable for hydro-meteorological applications. Unfortunately, rain gauge measurements are sparse and unevenly distributed, which substantially hampers the use of in-situ precipitation data in many regions of the world. The increasing availability of high-resolution gridded precipitation products presents a valuable alternative, especially over gauge-sparse regions. Nevertheless, uncertainties and corresponding differences across products can limit the applicability of these data. This study examines the usefulness of current state-of-the-art precipitation datasets in hydrological modelling. For this purpose, we force a conceptual hydrological model with multiple precipitation datasets in > 200 European catchments. We consider a wide range of precipitation products, which are generated via (1) interpolation of gauge measurements (E-OBS and GPCC V.2018), (2) combination of multiple sources (MSWEP V2) and (3) data assimilation into reanalysis models (ERA-Interim, ERA5, and CFSR). For each catchment, runoff and evapotranspiration simulations are obtained by forcing the model with the various precipitation products. Evaluation is done at the monthly time scale during the period of 1984–2007. We find that simulated runoff values are highly dependent on the accuracy of precipitation inputs, and thus show significant differences between the simulations. By contrast, simulated evapotranspiration is generally much less influenced. The results are further analysed with respect to different hydro-climatic regimes. We find that the impact of precipitation uncertainty on simulated runoff increases towards wetter regions, while the opposite is observed in the case of evapotranspiration. Finally, we perform an indirect performance evaluation of the precipitation datasets by comparing the runoff simulations with streamflow observations. Thereby, E-OBS yields the best agreement, while furthermore ERA5, GPCC V.2018 and MSWEP V2 show good performance. In summary, our findings highlight a climate-dependent propagation of precipitation uncertainty through the water cycle; while runoff is strongly impacted in comparatively wet regions such as Central Europe, there are increasing implications on evapotranspiration towards drier regions.

Complete kinematic calibration of a 6-RRRPRR parallel kinematic machine based on the optimal measurement configurations

2019 ◽  
Vol 234 (1) ◽  
pp. 121-136 ◽  
Author(s):  
Chunyang Han ◽  
Yang Yu ◽  
Zhenbang Xu ◽  
Xiaoming Wang ◽  
Peng Yu ◽  
...  
Keyword(s):  
Kinematic Model ◽  
Inverse Kinematic ◽  
Error Model ◽  
Kinematic Calibration ◽  
Universal Joint ◽  
Parallel Kinematic Mechanism ◽  
Simulation And Experiment ◽  
Parallel Kinematic ◽  
Kinematic Mechanism ◽  
Selection Of

This paper presents a kinematic calibration of a 6-RRRPRR parallel kinematic mechanism with offset RR-joints that would be applied in space positioning field. In order to ensure highly accurate and highly effective calibration process, the complete error model, which contains offset universal joint errors, is established by differentiating inverse kinematic model. A calibration simulation comparison with non-complete error model shows that offset universal joint errors are crucial to improve the calibration accuracy. Using the error model, an optimal calibration configuration selection algorithm is developed to determine the least number of measurement configurations as well as the optimal selection of these configurations from the feasible configuration set. To verify the effectiveness of kinematic calibration, a simulation and experiment were performed. The results show that the developed approach can effectively improve accuracy of a parallel kinematic mechanism with relatively low number of calibration configurations.

Research on Inverse Kinematic Design of a Certain Hydraulic Stewart Platform

2011 ◽  
Vol 58-60 ◽  
pp. 2442-2445
Author(s):  
Zhi Yong Qu ◽  
Zheng Mao Ye
Keyword(s):  
Machine Tools ◽  
Stewart Platform ◽  
Inverse Kinematic ◽  
Design And Optimization ◽  
Kinematic Design ◽  
Structural Rigidity ◽  
The Future ◽  
Stewart Platforms ◽  
Kinematic Loop ◽  
Motion Dynamics

Stewart platforms have recently attracted attention as simulator and machine tools because of their conceptual potentials in high motion dynamics and accuracy combined with high structural rigidity due to their closed kinematic loop. This paper, composed of inverse kinematic design and optimization, attempts to ground the foundation on dynamics design and choice in the future.

Sensitivity analysis of a six degrees of freedom displacement measuring device

2013 ◽  
Vol 228 (1) ◽  
pp. 158-168 ◽  
Author(s):  
Andrea Mura
Keyword(s):  
Sensitivity Analysis ◽  
Performance Analysis ◽  
Degrees Of Freedom ◽  
Stewart Platform ◽  
Inverse Kinematic ◽  
Measuring Device ◽  
Six Degrees Of Freedom ◽  
Geometrical Characteristics

Object of this paper is the performance analysis of a six degrees of freedom measuring device based on a modified Stewart platform structure. Because of the device studied in this work represents a novel application of a Stewart like platform, an investigation about its performance has been done, in order to evaluate both behaviour and characteristics of this device in different geometrical configurations. In particular, sensitivity analysis has been carried on about geometrical characteristics and displacements amplitude. To calculate the sensitivity, the inverse kinematic equations of the device have been obtained.

Kinematics, Dynamics and Vibration Models for 3RPR Parallel Kinematics Manipulator

2013 ◽  
Author(s):  
Bashar El-Khasawneh ◽  
Anas Alazzam
Keyword(s):  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Inverse Kinematic ◽  
Parallel Kinematics ◽  
Stiffness Modeling ◽  
Noise Rejection ◽  
Parallel Link ◽  
Parallel Kinematic ◽  
Kinematic Mechanisms ◽  
Dynamics And Vibration

Parallel link manipulators are the type of mechanisms that have closed kinematics chains. Some of their advantages over open kinematics chains (called also serial kinematics manipulators) are their high stiffness and accuracy. This paper carries out forward and inverse kinematic and dynamic analysis on a certain type of parallel kinematic mechanisms. This is needed to conduct vibration analysis on the same platform. The type of mechanism is planar 3 RPR manipulator. This entails identifying the modes of the manipulator. A simplified vibration theoretical model is derived. This derivation helps in the optimization of parallel kinematics machine design for improved/optimized dynamic performance. The implications of dynamic stiffness modeling should reflect on better noise rejection, less chatter during machining, and increasing the bandwidth of such mechanisms to admit running at higher speeds.

scholarly journals Workspace Identification of Stewart Platform

2020 ◽  
Vol 9 (3) ◽  
pp. 1903-1907
Keyword(s):  
Stewart Platform ◽  
Inverse Kinematic ◽  
Kinematic Modeling ◽  
Piston Motion ◽  
Platform Motion ◽  
Cylinder Piston ◽  
Moving Platform ◽  
The Individual ◽  
Platform Motions

The workspace identification of 6-DOF Stewart Platform has been done in this paper through inverse kinematic modeling. This Stewart Platform has six linear cylinder–piston actuators connected within fixed and the moving platform. The motions of the moving platform such as surge, sway, heave, roll, pitch and yaw have been generated from the combined motions of piston of actuators. The mathematical formulations for Inverse-Kinematic modeling of Stewart Platform have been formulated to find out the individual piston motion for the required platform motion. The platform motions and the actuator motions have been studied for the workspace identification of the Stewart Platform.

scholarly journals Panorama cienciométrico de la biotecnología en el sector agropecuario y agroindustrial

2020 ◽  
Vol 19 (1) ◽  
pp. 79-91
Author(s):  
María Alejandra Valverde Valverde ◽  
Carolina Delgado Hurtado ◽  
Carlos Felipe Rengifo Rodas
Keyword(s):  
Latin American ◽  
American Studies ◽  
Major Element ◽  
Specific Area ◽  
Scientific Production ◽  
Latin American Studies ◽  
Industrial Sectors ◽  
Current State ◽  
Global Challenges ◽  
Socially Relevant

This article presents Scientometrics as a major element in quantitatively addressing the study of a field of knowledge. This study seeks to combine complementarily and integrally the bibliometry with the technological outlook to obtain an image of the current state of biotechnology in a specific area. This contributes with a trend-setting in a socially relevant sector that currently addresses global challenges such as climate change and energy and food security. Through a bibliometric study, it determines the dynamics of the scientific production, key authors, country participation and language trends in the domain of Biotechnology in the agricultural and agro-industrial sectors. In addition, a technological outlook is presented, in which, based on the analysis of trends in patents, the innovative state of the area is established. The main result is associated with the dynamics of scientific production, which according to the Lotka law; states that the percentage of authors who produce N articles is inversely proportional to a power of N. The technological outlook is consistent with the Latin American studies, concluding that, despite of the increasing dynamics, there is a poor development of technology in the sector.

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