scholarly journals Angle Tracking Observer with Improved Accuracy for Resolver-to-Digital Conversion

Symmetry ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1347 ◽  
Author(s):  
Haoye Qin ◽  
Zhong Wu
Keyword(s):  
Phase Error ◽  
Angular Position ◽  
Position Estimation ◽  
High Order ◽  
Phase Detector ◽  
Type Ii ◽  
Digital Conversion ◽  
Estimation Errors ◽  
Angle Tracking ◽  
Acceleration Signals

A resolver is an absolute shaft sensor which outputs pair signals with ortho-symmetric amplitudes. Ideally, they are sinusoidal and cosinusoidal functions of the shaft angle. In order to demodulate angular position and velocity from resolver signals, resolver-to-digital conversion (RDC) is necessary. In software-based RDC, most algorithms mainly employ a phase-locked loop (PLL)-based angle tracking observer (ATO) to form a type-II system. PLL can track the detected angle by regulating the phase error from the phase detector which depends on the feature of orthogonal symmetry in the resolver outputs. However, a type-II system will result in either steady-state errors or cumulative errors in the estimation of angular position with constant accelerations. Although type-III ATOs can suppress these errors, they are still vulnerable to high-order acceleration signals. In this paper, an improved PLL-based ATO with a compensation model is proposed. By using dynamic compensation, the proposed ATO becomes a type-IV system and can reduce position estimation errors for high-order acceleration signals. In addition, the parameters of ATO can be tuned according to the bandwidth, noise level and capability of error suppression. Simulation and experimental results demonstrate the effectiveness of the proposed method.

Adaptive Observer of Rotor Position and Flux for Salient Synchronous Motor

2019 ◽  
Vol 20 (2) ◽  
pp. 114-121
Author(s):  
D. N. Bazylev ◽  
A. A. Pyrkin ◽  
A. A. Bobtsov
Keyword(s):  
Permanent Magnets ◽  
Adaptive Estimation ◽  
Angular Position ◽  
Regression Function ◽  
Estimation Algorithm ◽  
Synchronous Motor ◽  
Position Estimation ◽  
Adaptive Observer ◽  
Estimation Errors ◽  
Persistent Excitation

An algorithm of adaptive estimation of rotor flux and angular position for the salient synchronous motor with permanent magnets is presented. A new nonlinear parameterization of the dynamic motor model is proposed. Due to this parameterization the problem of position estimation is translated to the task of identification of unknown constant parameters. During the synthesis of estimation algorithm the currents and voltages of the stator windings, as well as the rotor speed, are assumed to be known signals. Two variants of the adaptive observer based on the standard gradient estimator and the algorithm of the dynamic extension of the regressor are proposed. It is proved that the both versions of the observer provide global exponential convergence of estimation errors to zero if the corresponding regression function satisfies the persistent excitation condition. Also, the latter version of the observer provides global asymptotic convergence if the regression function is square integrable. The results of numerical simulation demonstrate that the algorithm with the dynamic extension of the regressor provides a better quality of estimation transient processes in comparison with the standard gradient estimator.

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.

A new reaching law for sliding mode observer of controllable excitation linear synchronous motor

2021 ◽  
pp. 014233122110320
Author(s):  
Xiaolei Shi ◽  
Yipeng Lan ◽  
Yunpeng Sun ◽  
Cheng Lei
Keyword(s):  
Sliding Mode ◽  
Dynamic Performance ◽  
Angular Position ◽  
Lyapunov Stability Theory ◽  
Synchronous Motor ◽  
Position Estimation ◽  
Sliding Mode Observer ◽  
Sigmoid Function ◽  
Reaching Law ◽  
Linear Synchronous Motor

This paper presents a sliding mode observer (SMO) with new reaching law (NRL) for observing the real-time linear speed of a controllable excitation linear synchronous motor (CELSM). For the purpose of balancing the dilemma between the rapidity requirement of dynamic performance and the chattering reduction on sliding mode surface, the proposed SMO with NRL optimizes the reaching way of the conventional constant rate reaching law (CRRL) to the sliding mode surface by connecting the reaching process with system states and the sliding mode surface. The NRL is based on sigmoid function and power function, with proper options of exponential term and power term, the NRL is capable of eliminating the effect of chattering on accuracy of the angular position estimation and speed estimation. Compared with conventional CRRL, the SMO with NRL achieves suppressing the chattering phenomenon and tracking the transient process rapidly and accurately. The stability analysis is given to prove the convergence of the SMO through the Lyapunov stability theory. Simulation and experimental results show the effectiveness of the proposed NRL method.

scholarly journals Experimental Comparison between Event and Global Shutter Cameras

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1137
Author(s):  
Ondřej Holešovský ◽  
Radoslav Škoviera ◽  
Václav Hlaváč ◽  
Roman Vítek
Keyword(s):  
High Speed ◽  
Ground Truth ◽  
Motion Blur ◽  
Position Estimation ◽  
Estimation Accuracy ◽  
Experimental Comparison ◽  
Estimation Errors ◽  
Detection Rates ◽  
Ballistic Experiment ◽  
Event Camera

We compare event-cameras with fast (global shutter) frame-cameras experimentally, asking: “What is the application domain, in which an event-camera surpasses a fast frame-camera?” Surprisingly, finding the answer has been difficult. Our methodology was to test event- and frame-cameras on generic computer vision tasks where event-camera advantages should manifest. We used two methods: (1) a controlled, cheap, and easily reproducible experiment (observing a marker on a rotating disk at varying speeds); (2) selecting one challenging practical ballistic experiment (observing a flying bullet having a ground truth provided by an ultra-high-speed expensive frame-camera). The experimental results include sampling/detection rates and position estimation errors as functions of illuminance and motion speed; and the minimum pixel latency of two commercial state-of-the-art event-cameras (ATIS, DVS240). Event-cameras respond more slowly to positive than to negative large and sudden contrast changes. They outperformed a frame-camera in bandwidth efficiency in all our experiments. Both camera types provide comparable position estimation accuracy. The better event-camera was limited by pixel latency when tracking small objects, resulting in motion blur effects. Sensor bandwidth limited the event-camera in object recognition. However, future generations of event-cameras might alleviate bandwidth limitations.

Continuous angular position estimation of human ankle during unconstrained locomotion

2020 ◽  
Vol 60 ◽  
pp. 101968 ◽  
Author(s):  
Rohit Gupta ◽  
Inderjeet Singh Dhindsa ◽  
Ravinder Agarwal
Keyword(s):  
Angular Position ◽  
Position Estimation ◽  
Human Ankle

scholarly journals Comparative Evaluation of a Permanent Magnet Machine Saliency-Based Drive with Sine-Wave and Square-Wave Voltage Injection

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2189 ◽  
Author(s):  
Jyun-You Chen ◽  
Shih-Chin Yang ◽  
Kai-Hsiang Tu
Keyword(s):  
Permanent Magnet ◽  
Pulse Width Modulation ◽  
Dead Time ◽  
Sine Wave ◽  
Position Estimation ◽  
Feedback Signal ◽  
Estimation Errors ◽  
Square Wave ◽  
Position Errors ◽  
Voltage Signal

This paper improves a permanent magnet (PM) machine saliency-based drive performance based on the selection of a suitable injection signal. For the saliency-based position estimation, a persistently high-frequency (HF) voltage signal is injected to obtain a measurable spatial saliency feedback signal. The injection signal can be sine-wave or square-wave alternating current (AC) voltage manipulated by the inverter’s pulse width modulation (PWM). Due to the PWM dead-time effect, these HF voltage injection signals might be distorted, leading to secondary harmonics on the saliency signal. In addition, the flux saturation in machine rotors also results in other saliency harmonics. These nonlinear attributes cause position estimation errors on saliency-based drives. In this paper, two different voltage signals are analyzed to find a suited voltage which is less sensitive to these nonlinear attributes. Considering the inverter dead-time, a sine-wave voltage signal reduces its influence on the saliency signal. By contrast, the flux saturation causes the same amount of error on two injection signals. Analytical equations are developed to investigate position errors caused by the dead-time and flux saturation. An interior PM machine with the saliency ratio of 1.41 is tested for the experimental verification.

scholarly journals Optical Enhancement of Exoskeleton-Based Estimation of Glenohumeral Angles

2016 ◽  
Vol 2016 ◽  
pp. 1-20 ◽  
Author(s):  
Camilo Cortés ◽  
Luis Unzueta ◽  
Ana de los Reyes-Guzmán ◽  
Oscar E. Ruiz ◽  
Julián Flórez
Keyword(s):  
Estimation Method ◽  
Position Estimation ◽  
Accurate Estimation ◽  
Joint Angles ◽  
Estimation Errors ◽  
Marker Position ◽  
Human Movements ◽  
Posture Estimation ◽  
Kinematic Models ◽  
Method Accuracy

In Robot-Assisted Rehabilitation (RAR) the accurate estimation of the patient limb joint angles is critical for assessing therapy efficacy. In RAR, the use of classic motion capture systems (MOCAPs) (e.g., optical and electromagnetic) to estimate the Glenohumeral (GH) joint angles is hindered by the exoskeleton body, which causes occlusions and magnetic disturbances. Moreover, the exoskeleton posture does not accurately reflect limb posture, as their kinematic models differ. To address the said limitations in posture estimation, we propose installing the cameras of an optical marker-based MOCAP in the rehabilitation exoskeleton. Then, the GH joint angles are estimated by combining the estimated marker poses and exoskeleton Forward Kinematics. Such hybrid system prevents problems related to marker occlusions, reduced camera detection volume, and imprecise joint angle estimation due to the kinematic mismatch of the patient and exoskeleton models. This paper presents the formulation, simulation, and accuracy quantification of the proposed method with simulated human movements. In addition, a sensitivity analysis of the method accuracy to marker position estimation errors, due to system calibration errors and marker drifts, has been carried out. The results show that, even with significant errors in the marker position estimation, method accuracy is adequate for RAR.

scholarly journals Design and Comparative Study of Advanced Adaptive Control Schemes for Position Control of Electronic Throttle Valve

Information ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 65 ◽  
Author(s):  
Amjad Humaidi ◽  
Akram Hameed
Keyword(s):  
Adaptive Control ◽  
Position Control ◽  
Sliding Mode ◽  
Angular Position ◽  
Estimation Errors ◽  
Electronic Throttle ◽  
Control Schemes ◽  
Backstepping Controller ◽  
Matlab Package ◽  
The Stability

This paper investigates the performance of two different adaptive control schemes for controlling the angular position of an electronic throttle (ET) plate. The adaptive backstepping controller and adaptive sliding mode backstepping controller are the controllers under consideration. The control design based on these adaptive controllers is firstly addressed and the stability analysis of each controller has been presented and the convergence of both position and estimation errors for both controllers have been proved. A comparison study of the performance of both controllers has been conducted in terms of system transient characteristics and the behavior of their associated adaptive gain. The simulation has been implemented within the environment of the MATLAB package.

Syntheses of Dimeric Securinega Alkaloids

Synlett ◽  
2017 ◽  
Vol 28 (18) ◽  
pp. 2353-2359 ◽  
Author(s):  
Sunkyu Han ◽  
Sangbin Jeon ◽  
Joonoh Park
Keyword(s):  
Natural Products ◽  
High Order ◽  
Molecular Structures ◽  
Type I ◽  
Type Ii ◽  
Type Iii ◽  
Organic Community

The isolation of flueggenines A and B by Yue and co-workers in 2006 has triggered a burst of isolation reports of dimeric and oligomeric securinega alkaloid natural products. The compelling molecular structures of these compounds with various modes of connection between monomeric securinega units have posed intriguing challenges to the synthetic organic community. Herein, we have categorized high-order securinega alkaloids based on their biosynthetic mode of dimerization or oligomerization. We then have compiled all reported syntheses of dimeric securinega alkaloids based on our classification.1 Introduction2 Categorization of High-Order Securinega Alkaloid Natural Products3 Syntheses of Type I Dimeric Securinega Alkaloids4 Syntheses of Type II Dimeric Securinega Alkaloids5 Synthesis of Type III Dimeric Securinega Alkaloid6 Conclusion

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