scholarly journals Self-Calibration for the General Cable-Driven Serial Manipulator with Multi-Segment Cables

Electronics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 444
Author(s):  
Ya’nan Lou ◽  
Haoyu Lin ◽  
Pengkun Quan ◽  
Dongbo Wei ◽  
Shichun Di
Keyword(s):  
Motion Control ◽  
Tracking Error ◽  
Motion Controller ◽  
Self Calibration ◽  
Calibration Problem ◽  
Before And After ◽  
Calibration Algorithm ◽  
Complete Set ◽  
Control Accuracy ◽  
Calibration Parameters

This paper focuses on the kinematic calibration problem for the general cable-driven serial manipulator (CDSM) with multi-segment cables to improve its motion control accuracy. Firstly, to fully describe the calibration parameters of cables, links, joint positions, and the transmission system, this paper proposes a new cable routing description method named cable-routing configuration struct (CRCS), which provides a complete set of parameters to be calibrated for the proposed self-calibration algorithm. Then, a self-calibration algorithm for CDSM with motor incremental encoders is proposed, which can calibrate the robot at one time only using sufficient measured motor and joint positions. Its premise, the initial cable length, needs to be calibrated. Finally, the parameters of a three-DOF (degree of freedom) six-cable CDSM were described using the CRCS description method, and a comparative experiment was carried out on the same motion controller using the parameters before and after calibration. The experiment results of trajectory tracking error showed that the calibration parameters obtained by the proposed calibration algorithm can significantly improve the motion control accuracy of the three-DOF six-cable CDSM. This verified the correctness and effectiveness of the proposed calibration algorithm.

Development and motion control of spatial serial robotic manipulator under varying disturbances

2019 ◽  
Vol 16 (4) ◽  
pp. 460-467
Author(s):  
Alex Barre Epenetus ◽  
Meera CS ◽  
Santhakumar Mohan ◽  
Mukul Kumar Gupta
Keyword(s):  
Motion Control ◽  
Tracking Error ◽  
Robotic Manipulator ◽  
Superior Performance ◽  
Control Technique ◽  
Motion Controller ◽  
Content Type ◽  
Joint Friction ◽  
Dynamics Response ◽  
Torque Observer

Purpose Key challenges in evaluating the performance of a robotic manipulator are disturbances that rise internally and externally. Effects of non-linear disturbances like varying payload and joint friction can adversely affect the tracking performance in a robotic manipulator. This paper aims to discuss motion control of a three-link spatial manipulator using a computed torque observer-based control technique. Design/methodology/approach The overall motion control problem consists of derivation of kinematic and dynamic model of the manipulator followed by the control design to achieve desired manipulator response. In this study, the manipulator is subjected to uncertain varying load disturbances. The proposed motion controller compensates the effect of the disturbances and guarantees the convergence of tracking error to steady state value. Findings One major advantage of using observer-based control is positioning accuracy with robustness to parameter uncertainty and fast dynamics response. The performance of the proposed control technique is validated through real-time experiments conducted on the manipulator. The experiment results confirm the superior performance of the control system in achieving perfect tracking. Originality/value This paper demonstrates an observer-based control technique over a serial spatial manipulator which can be applied different robotic configurations under the effect of varying disturbances.

Calibration and Uncertainty Quantification of Gas Turbine Performance Models

2015 ◽  
Author(s):  
Manuel Arias Chao ◽  
Darrel S. Lilley ◽  
Peter Mathé ◽  
Volker Schloßhauer
Keyword(s):  
Uncertainty Quantification ◽  
Gas Turbine ◽  
Bayesian Approach ◽  
Least Squares Method ◽  
Measurement Data ◽  
Operating Conditions ◽  
Performance Models ◽  
Regression Problem ◽  
Calibration Problem ◽  
Calibration Parameters

Calibration and uncertainty quantification for gas turbine (GT) performance models is a key activity for GT manufacturers. The adjustment between the numerical model and measured GT data is obtained with a calibration technique. Since both, the calibration parameters and the measurement data are uncertain the calibration process is intrinsically stochastic. Traditional approaches for calibration of a numerical GT model are deterministic. Therefore, quantification of the remaining uncertainty of the calibrated GT model is not clearly derived. However, there is the business need to provide the probability of the GT performance predictions at tested or untested conditions. Furthermore, a GT performance prediction might be required for a new GT model when no test data for this model are available yet. In this case, quantification of the uncertainty of the baseline GT, upon which the new development is based on, and propagation of the design uncertainty for the new GT is required for risk assessment and decision making reasons. By using as a benchmark a GT model, the calibration problem is discussed and several possible model calibration methodologies are presented. Uncertainty quantification based on both a conventional least squares method and a Bayesian approach will be presented and discussed. For the general nonlinear model a fully Bayesian approach is conducted, and the posterior of the calibration problem is computed based on a Markov Chain Monte Carlo simulation using a Metropolis-Hastings sampling scheme. When considering the calibration parameters dependent on operating conditions, a novel formulation of the GT calibration problem is presented in terms of a Gaussian process regression problem.

DUTY-CYCLED SPINNING BASED 3D MOTION CONTROL APPROACH FOR BEVEL-TIPPED FLEXIBLE NEEDLE INSERTION

2018 ◽  
Vol 18 (07) ◽  
pp. 1840017 ◽  
Author(s):  
QIN YAO ◽  
XUMING ZHANG
Keyword(s):  
Motion Control ◽  
Control Method ◽  
Tracking Error ◽  
Open Loop ◽  
Loop Control ◽  
3D Motion ◽  
Control Approach ◽  
Target Error ◽  
The Mean ◽  
Simulation Results

Flexible needle has been widely used in the therapy delivery because it can advance along the curved lines to avoid the obstacles like important organs and bones. However, most control algorithms for the flexible needle are still limited to address its motion along a set of arcs in the two-dimensional (2D) plane. To resolve this problem, this paper has proposed an improved duty-cycled spinning based three-dimensional (3D) motion control approach to ensure that the beveled-tip flexible needle can track a desired trajectory to reach the target within the tissue. Compared with the existing open-loop duty-cycled spinning method which is limited to tracking 2D trajectory comprised of few arcs, the proposed closed-loop control method can be used for tracking any 3D trajectory comprised of numerous arcs. Distinctively, the proposed method is independent of the tissue parameters and robust to such disturbances as tissue deformation. In the trajectory tracking simulation, the designed controller is tested on the helical trajectory, the trajectory generated by rapidly-exploring random tree (RRT) algorithm and the helical trajectory. The simulation results show that the mean tracking error and the target error are less than 0.02[Formula: see text]mm for the former two kinds of trajectories. In the case of tracking the helical trajectory, the mean tracking error target error is less than 0.5[Formula: see text]mm and 1.5[Formula: see text]mm, respectively. The simulation results prove the effectiveness of the proposed method.

Active disturbance rejection motion control of spherical robot with parameter tuning

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Manlu Liu ◽  
Rui Lin ◽  
Maotao Yang ◽  
Anaid V. Nazarova ◽  
Jianwen Huo
Keyword(s):  
Motion Control ◽  
Disturbance Rejection ◽  
Parameter Tuning ◽  
Pso Algorithm ◽  
State Equation ◽  
Expected Value ◽  
Spherical Robot ◽  
Motion Controller ◽  
Actual Case ◽  
Content Type

Purpose The characteristics of spherical robots, such as under-drive, non-holonomic constraints and strong coupling, make it difficult to establish its motion control model accurately. To improve the anti-interference performance of spherical robots in practical engineering, this paper proposes a spherical robot motion controller based on auto-disturbance rejection control (ADRC) with parameter tuning. Design/methodology/approach This paper considers the influences of the spherical shell, internal frame and pendulum on the movement of the spherical robot during the rotation to establish the multi-body dynamics model of the XK-I spherical robot. Due to the serious coupling problem of the dynamic model, the motion control state equation is constructed using linearization and decoupling. The XK-I spherical robot PSO-ADRC motion controller with parameter tuning function is designed by combining the state equation with the particle swarm optimization (PSO) algorithm. Finally, experiments are performed to evaluate the feasibility of PSO-ADRC in an actual case compared to ADRC, PSO-PID and PID. Findings By analyzing the required time to reach the expected value, the control stability and the fluctuation range of the standard deviation after reaching the expected value, the superiority of PSO-ADRC to ADRC, PSO-PID and PID is demonstrated in terms of the speed and anti-interference ability. Practical implications The proposed method can be applied to the robot control field. Originality/value A parameter-tuning method for auto-disturbance-rejection motion control of the spherical robot is proposed. According to the experimental results, the anti-interference ability of the spherical robot moving on uneven ground is improved. Therefore, it provides a foundation for the autonomous environmental monitoring of the spherical robot equipped with sensors.

Research on Control Precision of the Neutron Bandwidth Chopper

2012 ◽  
Vol 220-223 ◽  
pp. 1077-1083 ◽  
Author(s):  
Li Ru Zhao ◽  
Xiao Zhang Zhang ◽  
Kai Zhang ◽  
Tong Zhang
Keyword(s):  
Dynamic Balance ◽  
Tracking Error ◽  
Pulse Signal ◽  
Phase Tracking ◽  
Control Precision ◽  
Technical Requirements ◽  
Control Scheme ◽  
Precision Phase ◽  
Synchronous Pulse ◽  
Control Accuracy

Operation of neutron bandwidth limiting chopper requires high controlling precision. Phase difference between the chopper rotor and the synchronous pulse signal should be maintained to be fixed. Rotating frequency of the rotor needs to be very stable. To achieve the above technical requirements, control scheme, dynamic balance, and other means are made. Thus influences to control accuracy are effectively reduced, which are from rotor asymmetry and neutron absorbing materials. In the case described in this paper, phase tracking error was controlled under ±0.10752°with 90% confidence for the designed chopper.

Aiming at self-calibration of terrestrial laser scanners using only one single object and one single scan

2014 ◽  
Vol 8 (4) ◽  
Author(s):  
Christoph Holst ◽  
Heiner Kuhlmann
Keyword(s):  
Stochastic Model ◽  
Functional Model ◽  
Laser Scanner ◽  
Systematic Errors ◽  
Sampling Point ◽  
Single Object ◽  
Self Calibration ◽  
Laser Scanners ◽  
Scanning Geometry ◽  
Calibration Parameters

AbstractWhen using terrestrial laser scanners for high quality analyses, calibrating the laser scanner is crucial due to unavoidable misconstruction of the instrument leading to systematic errors. Consequently, the development of calibration fields for laser scanner self-calibration is widespread in the literature. However, these calibration fields altogether suffer from the fact that the calibration parameters are estimated by analyzing the parameter differences of a limited number of substitute objects (targets or planes) scanned from different stations. This study investigates the potential of self-calibrating a laser scanner by scanning one single object with one single scan. This concept is new since it uses the deviation of each sampling point to the scanned object for calibration. Its applicability rests upon the integration of model knowledge that is used to parameterize the scanned object. Results show that this calibration approach is feasible leading to improved surface approximations. However, it makes great demands on the functional model of the calibration parameters, the stochastic model of the adjustment, the scanned object and the scanning geometry. Hence, to gain constant and physically interpretable calibration parameters, further improvement especially regarding functional and stochastic model is demanded.

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