scholarly journals Position Estimation of Vehicle Based on Magnetic Marker: Time-Division Position Correction

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8274
Author(s):  
Yeun Sub Byun ◽  
Rag Gyo Jeong
Keyword(s):  
Correction Method ◽  
Position Estimation ◽  
Position Error ◽  
Absolute Position ◽  
Position Information ◽  
Magnetic Marker ◽  
Position Correction ◽  
The Absolute ◽  
Magnetic Markers ◽  
Time Division

During the automatic driving of a vehicle, the vehicle’s positional information is important for vehicle driving control. If fixed-point land markers such as magnetic markers are used, the vehicle’s current position error can be calculated only when a marker is detected while driving, and this error can be used to correct the estimation position. Therefore, correction information is used irregularly and intermittently according to the installation intervals of the magnetic markers and the driving speed. If the detected errors are corrected all at once using the position correction method, discontinuity of the position information can occur. This problem causes instability in the vehicle’s route guidance control because the position error fluctuates as the vehicle’s speed increases. We devised a time-division position correction method that calculates the error using the absolute position of the magnetic marker, which is estimated when the magnetic marker is detected, along with the absolute position information from the magnetic marker database. Instead of correcting the error at once when the position and heading errors are corrected, the correction is performed by dividing the errors multiple times until the next magnetic marker is detected. This prevents sudden discontinuity of the vehicle position information, and the calculated correction amount is used without loss to obtain stable and continuous position information. We conducted driving tests to compare the performances of the proposed algorithm and conventional methods. We compared the continuity of the position information and the mean error and confirmed the superiority of the proposed method in terms of these aspects.

scholarly journals A Novel Indirect Calibration Approach for Robot Positioning Error Compensation Based on Neural Network and Hand-Eye Vision

2019 ◽  
Vol 9 (9) ◽  
pp. 1940 ◽  
Author(s):  
Chi-Tho Cao ◽  
Van-Phu Do ◽  
Byung-Ryong Lee
Keyword(s):  
Neural Network ◽  
Position Error ◽  
Industrial Robots ◽  
Positional Error ◽  
Absolute Position ◽  
Position Errors ◽  
The Neural Network ◽  
Robot Positioning ◽  
The Absolute ◽  
Calibration Approach

It is well known that most of the industrial robots have excellent repeatability in positioning. However, the absolute position errors of industrial robots are relatively poor, and in some cases the error may reach even several millimeters, which make it difficult to apply the robot system to vehicle assembly lines that need small position errors. In this paper, we have studied a method to reduce the absolute position error of robots using machine vision and neural network. The position/orientation of robot tool-end is compensated using a vision-based approach combined with a neural network, where a novel indirect calibration approach is presented in order to gather information for training the neural network. In the simulation, the proposed compensation algorithm was found to reduce the positional error to 98%. On average, the absolute position error was 0.029 mm. The application of the proposed algorithm in the actual robot experiment reduced the error to 50.3%, averaging 1.79 mm.

Experimental Study on Application of DGPS-based Position Information to Automatic Driving Control

2001 ◽  
Vol 13 (4) ◽  
pp. 340-351 ◽  
Author(s):  
Manabu Omae ◽  
◽  
Takehiko Fujioka ◽  
Keyword(s):  
Control System ◽  
Experimental Studies ◽  
Time Estimation ◽  
Position Measurement ◽  
Absolute Position ◽  
Position Information ◽  
Automatic Driving ◽  
Automatic Steering ◽  
The Absolute ◽  
Estimation And Control

Experimental studies are conducted for investigating the possibility of automatic driving control systems based on absolute position information. Implementation of such control system requires a methodology of measuring the absolute position, and a control algorithm. In this paper, an accurate and real-time estimation of the absolute position by use of DGPS (Differential Global Positioning System) and sensors on a controlled vehicle is proposed. Automatic steering controller, automatic evasive controller, and a method of relative position measurement of neighboring vehicles are also proposed as application of position information to automatic driving control. Experiments are conducted using sedan-type vehicles. Experimental results validate the proposed estimation and control system, and provide the perspective of enhancing the automatic driving control system by use of the absolute position information.

scholarly journals Sensorless Pedalling Torque Estimation Based on Motor Load Torque Observation for Electrically Assisted Bicycles

Actuators ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 88
Author(s):  
Riccardo Mandriota ◽  
Stefano Fabbri ◽  
Matthias Nienhaus ◽  
Emanuele Grasso
Keyword(s):  
External Disturbance ◽  
State Observer ◽  
Position Estimation ◽  
Load Torque ◽  
Estimation Errors ◽  
Position Information ◽  
Longitudinal Dynamics ◽  
Rotor Position ◽  
Electrically Assisted ◽  
Motor Load

The need for reducing the cost of and space in Electrically Assisted Bicycles (EABs) has led the research to the development of solutions able to sense the applied pedalling torque and to provide a suitable electrical assistance avoiding the installation of torque sensors. Among these approaches, this paper proposes a novel method for the estimation of the pedalling torque starting from an estimation of the motor load torque given by a Load Torque Observer (LTO) and evaluating the environmental disturbances that act on the vehicle longitudinal dynamics. Moreover, this work shows the robustness of this approach to rotor position estimation errors introduced when sensorless techniques are used to control the motor. Therefore, this method allows removing also position sensors leading to an additional cost and space reduction. After a mathematical description of the vehicle longitudinal dynamics, this work proposes a state observer capable of estimating the applied pedalling torque. The theory is validated by means of experimental results performed on a bicycle under different conditions and exploiting the Direct Flux Control (DFC) sensorless technique to obtain the rotor position information. Afterwards, the identification of the system parameters together with the tuning of the control system and of the LTO required for the validation of the proposed theory are thoroughly described. Finally, the capabilities of the state observer of estimating an applied pedalling torque and of recognizing the application of external disturbance torques to the motor is verified.

scholarly journals Rotor Position Estimation Approaches for Sensorless Control of Permanent Magnet Traction Motor in Electric Vehicles: A Review

2021 ◽  
Vol 12 (1) ◽  
pp. 9
Author(s):  
Yong Li ◽  
Hao Wu ◽  
Xing Xu ◽  
Xiaodong Sun ◽  
Jindong Zhao
Keyword(s):  
Permanent Magnet ◽  
Sensorless Control ◽  
Position Estimation ◽  
Control Technology ◽  
Permanent Magnet Motor ◽  
Traction Motor ◽  
Position Information ◽  
Rotor Position ◽  
Control Techniques ◽  
Speed Range

Permanent magnet traction motor has the advantages of high efficiency, high power density, high torque density and quick dynamic response, which has been widely used in the traction field of electric vehicle. The high-performance control of permanent magnet traction motor depends on accurate rotor position information, which is usually obtained by using mechanical position sensors such as hall sensor, encoder and rotary transformer. However, the traditional mechanical sensor has the disadvantages of high cost, large volume and poor anti-interference ability, which limits the application of permanent magnet motor. The sensorless control technology is an effective way to solve the above-mentioned problem. Firstly, the sensorless control techniques of permanent magnet motor are classified. The sensorless control techniques of permanent magnet motor for rotor initial position, zero-low speed range, medium-high speed range and full speed range are deeply described and compared. Finally, the development trend of sensorless control technology of permanent magnet traction motor is prospected.

Development of a simultaneous imaging system to measure the optical and gamma ray images of Ir-192 source for high-dose-rate brachytherapy

2021 ◽  
Vol 16 (12) ◽  
pp. T12005
Author(s):  
J. Nagata ◽  
S. Yamamoto ◽  
Y. Noguchi ◽  
T. Nakaya ◽  
K. Okudaira ◽  
...  
Keyword(s):  
Dose Rate ◽  
Spatial Resolution ◽  
Gamma Camera ◽  
Gamma Ray ◽  
Imaging System ◽  
High Dose Rate ◽  
High Dose ◽  
Cmos Camera ◽  
Absolute Position ◽  
The Absolute

Abstract In high-dose-rate (HDR) brachytherapy, verification of the Ir-192 source's position during treatment is needed because such a source is extremely radioactive. One of the methods used to measure the source position is based on imaging the gamma rays from the source, but the absolute position in a patient cannot be confirmed. To confirm the absolute position, it is necessary to acquire an optical image in addition to the gamma ray image at the same time as well as the same position. To simultaneously image the gamma ray and optical images, we developed an imaging system composed of a low-sensitivity, high-resolution gamma camera integrated with a CMOS camera. The gamma camera has a 1-mm-thick cerium-doped yttrium aluminum perovskite (YAIO3: YAP(Ce)) scintillator plate optically coupled to a position-sensitive photomultiplier (PSPMT), and a 0.1-mm-diameter pinhole collimator was mounted in front of the camera to improve spatial resolution and reduce sensitivity. We employed the concept of a periscope by placing two mirrors tilted at 45 degrees facing each other in front of the gamma camera to image the same field of view (FOV) for the gamma camera and the CMOS camera. The spatial resolution of the imaging system without the mirrors at 100 mm from the Ir-192 source was 3.2 mm FWHM, and the sensitivity was 0.283 cps/MBq. There was almost no performance degradation observed when the mirrors were positioned in front of the gamma camera. The developed system could measure the Ir-192 source positions in optical and gamma ray images. We conclude that the developed imaging system has the potential to measure the absolute position of an Ir-192 source in real-time clinical measurements.

scholarly journals Glacial Geodetic Contributions to the Mass Balance and Dynamics of Ice Shelves

1988 ◽  
Vol 11 ◽  
pp. 89-94 ◽  
Author(s):  
D. Möller ◽  
B. Ritter
Keyword(s):  
Mass Balance ◽  
Collocation Method ◽  
Ice Shelf ◽  
Absolute Position ◽  
Ice Flow ◽  
Ice Shelves ◽  
Rotation Rates ◽  
Deformation Parameters ◽  
Satellite Methods ◽  
The Absolute

The glacial geodetic contribution to the mass balance and dynamics of ice shelves includes repeated determinations of the absolute position (ϕ,λ,Η) of selected points (using satellite methods), the establishment of relative positions (y,x,Δh) in deformation figures, and height measurements. The results are used to establish ice-flow velocities and directions, strain and rotation rates, and changes in height. Modelling of deformation parameters at a few points over a large ice shelf is made possible by the collocation method. Results of these observations and analysis of Ekström Ice Shelf for the period 1979–87 are reported.

scholarly journals The Method of Train Positioning Based on Digital Track Map Matching

2018 ◽  
Vol 246 ◽  
pp. 03024
Author(s):  
Pengfei Wang ◽  
Weidong Li ◽  
Xinping Wang ◽  
Xianwu Chu
Keyword(s):  
Correction Method ◽  
Position Estimation ◽  
Map Matching ◽  
Spline Curve ◽  
Positioning Method ◽  
Rail Line ◽  
Accurate Position ◽  
Train Positioning ◽  
Cubic Spline Curve ◽  
Track Line

A train positioning method based on GPS and digital rail line matching is proposed. Firstly, the digital track line is generated based on the fitting and interpolation algorithm of train track line. And then the GPS data are corrected by the track line positioning correction method, and the more accurate position estimation of the train is obtained. Finally, the data track line is simulated and analyzed with some measured data from Harbin to Qigihar track line. The analysis results show that cubic spline curve is better than cubic B-spline curve on the establishment of digital track map.

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