Optimal Configuration of Ultrasonic Sensors in a 3D Position Estimation System Using Genetic Algorithms

2001 ◽  
Author(s):  
Probir Kumar Ray ◽  
Nishant Unnikrishnan ◽  
Ajay Mahajan
Keyword(s):  
Autonomous Vehicles ◽  
Wave Theory ◽  
Position Estimation ◽  
Optimal Placement ◽  
Accurate Estimation ◽  
Delay Term ◽  
Electronic Circuitry ◽  
3D Space ◽  
The Difference ◽  
Estimation System

Abstract This paper provides a genetic algorithm based approach to calculate the optimal placement of receivers in a 3D position estimation system that uses the difference in the time-of-arrivals (TOA) of an ultrasonic wave from a transmitter to the different receivers fixed in 3D space. This is a different approach to traditional systems that use the actual time-of-flights (TOF) from the transmitter to the different receivers and triangulate the position of the transmitter. The new approach makes the system more accurate, makes the transmitter independent of the receivers and does not require the need of calculating the time delay term that is inherent in traditional systems due to delays caused by the electronic circuitry. This paper presents a thorough analysis of receiver configurations in the 2D and 3D system that lead to singularities, i.e. locations of receivers that lead to formulations that can not be solved due to a shortage of information. It provides guidelines of where not to place receivers, and further, presents a detailed analysis of locations that are optimal, i.e. locations that lead to the most accurate estimation of the transmitter positions. The results presented in this paper are not only applicable to ultrasonic systems, but all systems that use wave theory, e.g. infrared, laser, etc. This work finds applications in virtual reality cells, robotics, guidance of indoor autonomous vehicles and vibration analysis.

Accuracy Considerations in a 3-D Ultrasonic Positioning System Based on the Difference in Time of Flights

2002 ◽  
Vol 124 (4) ◽  
pp. 688-693 ◽  
Author(s):  
Nishant Unnikrishnan ◽  
Probir Kumar Ray ◽  
Ajay Mahajan ◽  
Tsuchin Chu
Keyword(s):  
Precision Measurement ◽  
Autonomous Vehicles ◽  
Vibration Analysis ◽  
Arrival Time ◽  
Wave Theory ◽  
Positioning System ◽  
Multiple Receivers ◽  
Critical Issues ◽  
Measurement Devices ◽  
The Difference

This paper presents a method to improve the accuracy of an ultrasonic 3-D positioning system that uses the differences in the time of flights from a single transmitter to multiple receivers. The paper presents techniques to overcome errors in ultrasonic systems due to critical issues such as misalignment of transducers, changes in the speed of sound, arrival time of signals, etc. Further, the work presented here is not just applicable to ultrasonic systems but to all systems based on wave theory. This work will impact applications in robotics, virtual reality, precision measurement devices and probes, guidance of autonomous vehicles, and vibration analysis.

An Intelligent Ultrasonic Based Neuro-Navigation System for Improved Image Guided Neurosurgery

2003 ◽  
Author(s):  
Jennifer Akers ◽  
Probir Kumar Ray ◽  
Ajay Mahajan ◽  
Sumeer Lal
Keyword(s):  
Genetic Algorithm ◽  
Position Estimation ◽  
Optimal Placement ◽  
Line Of Sight ◽  
Current Image ◽  
Laboratory Environment ◽  
Image Guided ◽  
Genetic Algorithm Approach ◽  
Estimation System ◽  
Better Than

This paper shows the feasibility of using an accurate 3D ultrasonic position estimation system for realtime image guided neurosurgery. Current image guided systems use camera based technology that is space-intensive, have an accuracy of about 2mm, and are prone to occasional failures. The 3D system presented in this paper eliminates the space intensive camera, has an accuracy better than 2mm in the operating range of about 20–40cm, makes the system independent of line-of-sight occlusion problems, and is expected to pave the way for accurate fusion models of MRI and ultrasonography to account for brain shifts during surgery. This paper presents the system formulation, optimal placement of receivers using an innovative genetic algorithm approach, a scheme for automatic installation and calibration, and finally some preliminary experimental results within a laboratory environment.

An Iterative Kalman Filter for a 3D Ultrasonic Position Estimation System

2007 ◽  
Author(s):  
Sanjeevi Chitikeshi ◽  
Ajay Mahajan ◽  
Jennifer Akers
Keyword(s):  
Kalman Filter ◽  
Inertial Frame ◽  
Position Estimation ◽  
Image Guided Surgery ◽  
Guided Surgery ◽  
Image Guided ◽  
Multiple Receivers ◽  
The Difference ◽  
Estimation System ◽  
Increase In Accuracy

This paper describes an iterative Kalman Filter to increase the accuracy of a dynamic 3D position estimation system. The novelty of the system lies in the fact that a difference in the time of arrivals is used in conjunction with an estimated speed of sound within the system formulation, and the Kalman Filter is used to further increase the accuracy and robustness of the output. The output is a 3D position of the transmitter obtained from the difference in time of arrivals of the wave burst at multiple receivers fixed within an inertial frame. Results are provided to show the increase in accuracy and robustness along with some limitations of the system. The system has many applications the most significant being image guided surgery.

scholarly journals Sensorless SPMSM Position Estimation Using Position Estimation Error Suppression Control and EKF in Wide Speed Range

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Zhanshan Wang ◽  
Longhu Quan ◽  
Xiuchong Liu
Keyword(s):  
Permanent Magnet ◽  
High Performance ◽  
Sensorless Control ◽  
Estimation Error ◽  
Position Estimation ◽  
Combination Method ◽  
Accurate Estimation ◽  
Rotor Position ◽  
Estimation System ◽  
Error Suppression

The control of a high performance alternative current (AC) motor drive under sensorless operation needs the accurate estimation of rotor position. In this paper, one method of accurately estimating rotor position by using both motor complex number model based position estimation and position estimation error suppression proportion integral (PI) controller is proposed for the sensorless control of the surface permanent magnet synchronous motor (SPMSM). In order to guarantee the accuracy of rotor position estimation in the flux-weakening region, one scheme of identifying the permanent magnet flux of SPMSM by extended Kalman filter (EKF) is also proposed, which formed the effective combination method to realize the sensorless control of SPMSM with high accuracy. The simulation results demonstrated the validity and feasibility of the proposed position/speed estimation system.

scholarly journals Depth-Average Velocity from Spray Underwater Gliders

2018 ◽  
Vol 35 (8) ◽  
pp. 1665-1673 ◽  
Author(s):  
Daniel L. Rudnick ◽  
Jeffrey T. Sherman ◽  
Alexander P. Wu
Keyword(s):  
Average Velocity ◽  
Dead Reckoning ◽  
Water Velocity ◽  
Accurate Estimation ◽  
Underwater Glider ◽  
Underwater Gliders ◽  
Before And After ◽  
The Difference ◽  
Using Data ◽  
Acoustic Doppler Current Profilers

AbstractThe depth-average velocity is routinely calculated using data from underwater gliders. The calculation is a dead reckoning, where the difference between the glider’s velocity over ground and its velocity through water yields the water velocity averaged over the glider’s dive path. Given the accuracy of global positioning system navigation and the typical 3–6-h dive cycle, the accuracy of the depth-average velocity is overwhelmingly dependent on the accurate estimation of the glider’s velocity through water. The calculation of glider velocity through water for the Spray underwater glider is described. The accuracy of this calculation is addressed using a method similar to that used with shipboard acoustic Doppler current profilers, where water velocity is compared before and after turns to determine a gain to apply to glider velocity through water. Differences of this gain from an ideal value of one are used to evaluate accuracy. Sustained glider observations of several years off California and Palau consisted of missions involving repeated straight sections, producing hundreds of turns. The root-mean-square accuracy of depth-average velocity is estimated to be in the range of 0.01–0.02 m s−1, consistent with inferences from the early days of underwater glider design.

scholarly journals Computational Solutions Based on Bayesian Networks to Hierarchize and to Predict Factors Influencing Gender Fairness in the Transport System: Four Use Cases

2021 ◽  
Vol 13 (20) ◽  
pp. 11372
Author(s):  
Gemma Dolores Molero ◽  
Sara Poveda-Reyes ◽  
Ashwani Kumar Malviya ◽  
Elena García-Jiménez ◽  
Maria Chiara Leva ◽  
...  
Keyword(s):  
Bayesian Networks ◽  
Transport System ◽  
Autonomous Vehicles ◽  
Personal Space ◽  
Use Cases ◽  
Railway Transport ◽  
Analytic Hierarchy ◽  
Perception Of Safety ◽  
Level 3 ◽  
The Difference

Previous studies have highlighted inequalities and gender differences in the transport system. Some factors or fairness characteristics (FCs) strongly influence gender fairness in the transport system. The difference with previous studies, which focus on general concepts, is the incorporation of level 3 FCs, which are more detailed aspects or measures that can be implemented by companies or infrastructure managers and operators in order to increase fairness and inclusion in each use case. The aim of this paper is to find computational solutions, Bayesian networks, and analytic hierarchy processes capable of hierarchizing level 3 FCs and to predict by simulation their values in the case of applying some improvements. This methodology was applied to data from women in four use cases: railway transport, autonomous vehicles, bicycle sharing stations, and transport employment. The results showed that fairer railway transport requires increased personal space, hospitality rooms, help points, and helpline numbers. For autonomous vehicles, the perception of safety, security, and sustainability should be increased. The priorities for bicycle sharing stations are safer cycling paths avoiding hilly terrains and introducing electric bicycles, child seats, or trailers to carry cargo. In transport employment, the priorities are fair recruitment and promotion processes and the development of family-friendly policies.

Elevation gaps in fluvial sandbar deposition and their implications for paleodepth estimation

Geology ◽  
2020 ◽  
Vol 48 (7) ◽  
pp. 718-722
Author(s):  
Jason S. Alexander ◽  
Brandon J. McElroy ◽  
Snehalata Huzurbazar ◽  
Marissa L. Murr
Keyword(s):  
Large Data ◽  
Accurate Estimation ◽  
Systematic Bias ◽  
Flow Depth ◽  
Mean Flow ◽  
Data Set ◽  
Bed Elevation ◽  
The Difference ◽  
Base Elevation ◽  
Thickness Measurements

Abstract Accurate estimation of paleo–streamflow depth from outcrop is important for estimation of channel slopes, water discharges, sediment fluxes, and basin sizes of ancient river systems. Bar-scale inclined strata deposited from slipface avalanching on fluvial bar margins are assumed to be indicators of paleodepth insofar as their thickness approaches but does not exceed formative flow depths. We employed a unique, large data set from a prolonged bank-filling flood in the sandy, braided Missouri River (USA) to examine scaling between slipface height and measures of river depth during the flood. The analyses demonstrated that the most frequent slipface height observations underestimate study-reach mean flow depth at peak stage by a factor of 3, but maximum values are approximately equal to mean flow depth. At least 70% of the error is accounted for by the difference between slipface base elevation and mean bed elevation, while the difference between crest elevation and water surface accounts for ∼30%. Our analysis provides a scaling for bar-scale inclined strata formed by avalanching and suggests risk of systematic bias in paleodepth estimation if mean thickness measurements of these deposits are equated to mean bankfull depth.

scholarly journals The role of vegetation in the CO2 flux from a tropical urban neighbourhood

2013 ◽  
Vol 13 (20) ◽  
pp. 10185-10202 ◽  
Author(s):  
E. Velasco ◽  
M. Roth ◽  
S. H. Tan ◽  
M. Quak ◽  
S. D. A. Nabarro ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Anthropogenic Activities ◽  
Co2 Flux ◽  
Accurate Estimation ◽  
Urban Vegetation ◽  
Co2 Uptake ◽  
Total Contribution ◽  
The Difference ◽  
Residential Neighbourhood

Abstract. Urban surfaces are usually net sources of CO2. Vegetation can potentially have an important role in reducing the CO2 emitted by anthropogenic activities in cities, particularly when vegetation is extensive and/or evergreen. A direct and accurate estimation of carbon uptake by urban vegetation is difficult due to the particular characteristics of the urban ecosystem and high variability in tree distribution and species. Here, we investigate the role of urban vegetation in the CO2 flux from a residential neighbourhood in Singapore using two different approaches. CO2 fluxes measured directly by eddy covariance are compared with emissions estimated from emissions factors and activity data. The latter includes contributions from vehicular traffic, household combustion, soil respiration and human breathing. The difference between estimated emissions and measured fluxes should approximate the flux associated with the aboveground vegetation. In addition, a tree survey was conducted to estimate the annual CO2 sequestration using allometric equations and an alternative model of the metabolic theory of ecology for tropical forests. Palm trees, banana plants and turfgrass were also included in the survey with their annual CO2 uptake obtained from published growth rates. Both approaches agree within 2% and suggest that vegetation sequesters 8% of the total emitted CO2 in the residential neighbourhood studied. An uptake of 1.4 ton km−2 day−1 (510 ton km−2 yr−1) was estimated as the difference between assimilation by photosynthesis minus the aboveground biomass respiration during daytime (4.0 ton km−2 day−1) and release by plant respiration at night (2.6 ton km−2 day−1). However, when soil respiration is added to the daily aboveground flux, the biogenic component becomes a net source amounting to 4% of the total CO2 flux and represents the total contribution of urban vegetation to the carbon flux to the atmosphere.

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