scholarly journals Symmetric Kullback-Leibler Metric Based Tracking Behaviors for Bioinspired Robotic Eyes

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Hengli Liu ◽  
Jun Luo ◽  
Peng Wu ◽  
Shaorong Xie ◽  
Hengyu Li
Keyword(s):  
Particle Filtering ◽  
Parallel Mechanism ◽  
Tracking System ◽  
Error Function ◽  
Tracking Error ◽  
Robot Motion ◽  
Control Scheme ◽  
Smooth Tracking ◽  
Spherical Parallel Mechanism ◽  
Human Eyes

A symmetric Kullback-Leibler metric based tracking system, capable of tracking moving targets, is presented for a bionic spherical parallel mechanism to minimize a tracking error function to simulate smooth pursuit of human eyes. More specifically, we propose a real-time moving target tracking algorithm which utilizesspatial histogramstaking into account symmetric Kullback-Leibler metric. In the proposed algorithm, the key spatial histograms are extracted and taken into particle filtering framework. Once the target is identified, an image-based control scheme is implemented to drive bionic spherical parallel mechanism such that the identified target is to be tracked at the center of the captured images. Meanwhile, the robot motion information is fed forward to develop an adaptive smooth tracking controller inspired by theVestibuloocular Reflexmechanism. The proposed tracking system is designed to make the robot track dynamic objects when the robot travels through transmittable terrains, especially bumpy environment. To performbumpy-resist capabilityunder the condition of violent attitude variation when the robot works in the bumpy environment mentioned, experimental results demonstrate the effectiveness and robustness of our bioinspired tracking system using bionic spherical parallel mechanism inspired by head-eye coordination.

scholarly journals Adaptive Event-Triggered Control Strategy for Ensuring Predefined Three-Dimensional Tracking Performance of Uncertain Nonlinear Underactuated Underwater Vehicles

Mathematics ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 137
Author(s):  
Jin Hoe Kim ◽  
Sung Jin Yoo
Keyword(s):  
Control Strategy ◽  
Dimensional Space ◽  
Error Function ◽  
Tracking Error ◽  
Three Dimensional ◽  
Underwater Vehicles ◽  
Tracking Performance ◽  
Control Scheme ◽  
Nonlinear Tracking ◽  
Event Triggered

This paper presents an adaptive event-triggered control strategy for guaranteeing predefined tracking performance of uncertain nonlinear underactuated underwater vehicles (UUVs) in the three-dimensional space. Compared with the related results in the literature, the main contribution of this paper is to develop a nonlinear error transformation approach for ensuring predefined three-dimensional tracking performance under the underactuated property of 6-DOF UUVs and limited network resources. A nonlinear tracking error function is designed using a linear velocity rotation matrix and a time-varying performance function. An adaptive event-triggered control scheme using the nonlinear tracking error function and neural networks is constructed to ensure the practical stability of the closed-loop system with predefined three-dimensional tracking performance. In the proposed control scheme, auxiliary stabilizing signals are designed to resolve the underactuated problem of UUVs. Simulation results are presented to illustrate the effectiveness of the theoretical methodology.

Studying noise immunity of radio information transmission systems with noise-like phase-shift keyed signals and synchronization delay errors

2019 ◽  
pp. 105-113
Author(s):  
G. N. Maltsev ◽  
A. V. Evteev
Keyword(s):  
Phase Shift ◽  
Information Transmission ◽  
Noise Immunity ◽  
Tracking System ◽  
Tracking Error ◽  
Information Symbol ◽  
Transmission Systems ◽  
Synchronization System ◽  
Correlation Receiver ◽  
Selection Of

Introduction: Radio information transmission systems with noise-like phase-shift keyed signals based on pseudo-random sequences have potential noise immunity provided by accurately tracking the delay of the received signal in the correlation receiver. When working with moving objects, the delay of the received signal varies continuously, and the reception quality for noise-like phase-shifted signals highly depends on the synchronization system operation and on the accuracy of estimating the received signal delay by the tracking system. To ensure the required signal reception quality, it is necessary to provide an informed choice of tracking system parameters, taking into account their effects, which are the random and systematic components of the delay tracking error, on the selected noise immunity indicator.Purpose: Analyzing how the errors in tracking the delay of a received phase-shift keyed signal based on a pseudorandom sequence by the synchronization system of a radio information transmission system can affect the probability of erroneous reception of an information symbol.Results: The calculation method was used to obtain families of dependencies of the probability of erroneous reception of an information symbol on the signal-noise ratio (SNR), and the values of the random and systematic components of the delay tracking error which are normalized to the capture band of the correlation receiver. It has been shown that at a fixed SNR, the values of the random and systematic components of the delay tracking error are critical for the erroneous reception probability. In all the cases discussed, all the dependencies are characterized by a slow change of the erroneous reception probability while the synchronization errors within the area of small SNR have fixed values. As the SNR value grows, the erroneous reception probability rapidly drops. To ensure the specified signal reception quality and the reliability of the selection of information symbols and messages in a radio information transmission system with noise-like phase-manipulated signals, its synchronization system requires a joint selection of the tracking system parameters, taking into account the limitations imposed by the operating conditions and technical implementation features.Practical relevance: The obtained results can be used in noise immunity analysis of radio information transmission systems with noise-like phase-shift keyed signals in a wide range of communication conditions, and in providing technical solutions for synchronization systems ensuring the required quality of signal reception.

scholarly journals Robot-assisted Ultrasound-guided Tracking of Anatomical Structures for the Application of Focused Ultrasound

2020 ◽  
Vol 6 (3) ◽  
pp. 123-126
Author(s):  
Michael Unger ◽  
Johann Berger ◽  
Bjoern Gerold ◽  
Andreas Melzer
Keyword(s):  
Focused Ultrasound ◽  
Varicose Veins ◽  
Tracking System ◽  
Tracking Error ◽  
Uterine Fibroids ◽  
High Intensity Focused Ultrasound ◽  
Robot Assisted ◽  
Anatomical Structures ◽  
Surgical Tool ◽  
Custom Made

AbstractHigh intensity focused ultrasound is used as a surgical tool to treat completely non-invasively several diseases. Examples of clinical applications are uterine fibroids, prostate cancer, thyroid nodules, and varicose veins. Precise targeting is key for improving the treatment outcome. A method for an automated, robot-assisted tracking system was developed and evaluated. A wireless ultrasound scanner was used to acquire images of the target, in this case, a blood vessel. The active contour approach by Chan and Vese was used to segment and track while moving the scanner along the target structure with a collaborative robotic arm. The performance was assessed using a custom made Agar phantom. The mean tracking error, which is defined as the remaining distance of the lesion to the images’ centre line, was 0.27 mm ± 0.18 mm.

scholarly journals A Study on Vision-Based Backstepping Control for a Target Tracking System

Actuators ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 105
Author(s):  
Thinh Huynh ◽  
Minh-Thien Tran ◽  
Dong-Hun Lee ◽  
Soumayya Chakir ◽  
Young-Bok Kim
Keyword(s):  
Control System ◽  
Visual Servoing ◽  
Tracking System ◽  
Experimental Studies ◽  
Imaging Geometry ◽  
Control Scheme ◽  
Decoupled Control ◽  
Control Configuration ◽  
A New Technique ◽  
Pointing Control

This paper proposes a new method to control the pose of a camera mounted on a two-axis gimbal system for visual servoing applications. In these applications, the camera should be stable while its line-of-sight points at a target located within the camera’s field of view. One of the most challenging aspects of these systems is the coupling in the gimbal kinematics as well as the imaging geometry. Such factors must be considered in the control system design process to achieve better control performances. The novelty of this study is that the couplings in both mechanism’s kinematics and imaging geometry are decoupled simultaneously by a new technique, so popular control methods can be easily implemented, and good tracking performances are obtained. The proposed control configuration includes a calculation of the gimbal’s desired motion taking into account the coupling influence, and a control law derived by the backstepping procedure. Simulation and experimental studies were conducted, and their results validate the efficiency of the proposed control system. Moreover, comparison studies are conducted between the proposed control scheme, the image-based pointing control, and the decoupled control. This proves the superiority of the proposed approach that requires fewer measurements and results in smoother transient responses.

scholarly journals Finite-Time Adaptive Fuzzy Control for Nonlinear Systems with Unknown Backlash-Like Hysteresis

2021 ◽  
Author(s):  
Shuzhen Diao ◽  
Wei Sun ◽  
Le Wang ◽  
Jing Wu
Keyword(s):  
Fuzzy Control ◽  
Finite Time ◽  
Fuzzy Systems ◽  
Tracking Error ◽  
Adaptive Fuzzy Control ◽  
Finite Time Stability ◽  
Adaptive Fuzzy ◽  
Intermediate Variable ◽  
Control Scheme ◽  
Theoretical Results

AbstractThis study considers the tracking control problem of the nonstrict-feedback nonlinear system with unknown backlash-like hysteresis, and a finite-time adaptive fuzzy control scheme is developed to address this problem. More precisely, the fuzzy systems are employed to approximate the unknown nonlinearities, and the design difficulties caused by the nonlower triangular structure are also overcome by using the property of fuzzy systems. Besides, the effect of unknown hysteresis input is compensated by approximating an intermediate variable. With the aid of finite-time stability theory, the proposed control algorithm could guarantee that the tracking error converges to a smaller region. Finally, a simulation example is provided to further verify the above theoretical results.

Wavelet Filter Approach for GPS Attitude Tracking System on Ship

2010 ◽  
Vol 450 ◽  
pp. 552-555
Author(s):  
Ping Wang ◽  
Kai Xue ◽  
Qiu Hong Li
Keyword(s):  
High Frequency ◽  
Tracking System ◽  
Tracking Error ◽  
Low Frequency ◽  
Attitude Measurement ◽  
Visual Effects ◽  
Error Sources ◽  
Attitude Tracking ◽  
Servo Mechanism ◽  
Filter Approach

GPS attitude tracking system on the ship is a servo mechanism which could be used for counteracting the effects of the ship’s pitch and roll. But the attitude measurement precision of ship is more important to the tracking precision of the servo mechanism. As one of the major error sources, the noises of GPS attitude measurement bring out the steady tracking error of the tracking servo mechanism. To reduce the steady error due to the noise, the threshold noise removing method of wavelet is used to eliminate the noise. And the better result with the meaning of standard deviation and the better visual effects could be gotten by using the method. The signals of the processed high frequency and the retained low frequency could be reconstructed with the original signals. Therefore, the signals after noise removing could be obtained. The threshold noise removing method of wavelet used to remove the noise of GPS attitude information in the paper is of great value in practice.

Robust fault-tolerant tracking control for a class of nonlinear systems based on position measurements only

2016 ◽  
Vol 230 (6) ◽  
pp. 486-497 ◽  
Author(s):  
Gang Shen ◽  
Zhen-Cai Zhu ◽  
Xiang Li ◽  
Qiang Meng ◽  
Yu Tang ◽  
...  
Keyword(s):  
Nonlinear Systems ◽  
Fault Tolerant ◽  
Tracking System ◽  
High Quality ◽  
Differential Signal ◽  
Time Dynamic ◽  
Closed Loop Systems ◽  
Controlled Systems ◽  
Attitude Tracking ◽  
Control Scheme

The problem of trajectory tracking for a class of nonlinear systems in the presence of un-modeled dynamics, parameter variations and even the actuator faults is investigated in this paper. A novel fault-tolerant control scheme is proposed by combining the nominal model-based controller and time-delay controller, which are adopted to achieve the real-time dynamic compensation and guarantee the robust stability of the controlled systems, respectively. Moreover, high-quality differential signals are unavailable in the presence of disturbances and measurement noise, which limit the performance of closed-loop systems in practice. Therefore, an extended state observer (ESO) is introduced to obtain high-quality differential signal estimations based on position measurements only. Furthermore, the effectiveness of the proposed novel control scheme is verified by testing in the spacecraft attitude tracking system.

A Novel Concept for Energy-Optimal, Independent-Phase Control of Brushless Motor Drivers

2021 ◽  
pp. 1-11
Author(s):  
Amin Ghorbanpour ◽  
Hanz Richter
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Robot Motion ◽  
Control Law ◽  
Outer Loop ◽  
Energy Regeneration ◽  
Brushless Motor ◽  
Control Scheme ◽  
Novel Concept ◽  
Constrained Quadratic Optimization

Abstract In this work, a new drive concept for brushless direct current (BLDC) motors is introduced. Energy regeneration is optimally managed with the aim of improving the energy efficiency of robot motion controls. The proposed scheme has three independent regenerative drives interconnected in a wye configuration. An augmented model of the robot, joint mechanisms, and BLDC motors is formed, and then a voltage-based control scheme is developed. The control law is obtained by specifying an outer-loop torque controller followed by minimization of power consumption via online constrained quadratic optimization. An experiment is conducted to assess the performance of the proposed concept against an off-the-shelf driver. It is shown that, in terms of energy regeneration and consumption, the developed driver has better performance. Furthermore, the proposed concept showed a reduction of 15% energy consumption for the conditions of the study.

Sign in / Sign up

Export Citation Format

Share Document