scholarly journals Nonlinear Position Control Using Only Position Feedback under Position Errors and Yaw Constraints for Air Bearing Planar Motors

Mathematics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 1354
Author(s):  
Wonhee Kim ◽  
Donghoon Shin ◽  
Youngwoo Lee
Keyword(s):  
Position Control ◽  
Position Error ◽  
Nonlinear Observer ◽  
Closed Loop System ◽  
Tracking Errors ◽  
Position Errors ◽  
Full State ◽  
Position Feedback ◽  
Position Controller ◽  
The Stability

In this paper, we propose a nonlinear position control using only position feedback to guarantee the tolerances for position tracking errors and yaw. In the proposed method, both mechanical and electrical dynamics are considered. The proposed method consists of the nonlinear position controller and nonlinear observer. The nonlinear position controller is designed by a backstepping procedure using the barrier Lyapunov function to satisfy the constraints of position error and yaw. The nonlinear observer is developed to estimate full state using only position feedback. The stability of the closed-loop system is proven using Lyapunov and input-to-state stabilities. Consequently, the proposed method satisfies the constraints of position error and yaw using only position feedback for the planar motor.

scholarly journals Nonlinear Position Control with Nonlinear Coordinate Transformation Using Only Position Measurement for Single-Rod Electro-Hydrostatic Actuator

Mathematics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 1273
Author(s):  
Wonhee Kim ◽  
Daehee Won
Keyword(s):  
Coordinate Transformation ◽  
Position Control ◽  
Internal State ◽  
Pressure Sensors ◽  
Nonlinear Observer ◽  
Position Tracking ◽  
State Variables ◽  
Position Measurement ◽  
Full State ◽  
Position Controller

In existing methods, full-state feedback is required for the position tracking of single-rod Electro Hydrostatic Actuators (EHAs). Measuring a full state is not always possible because of cost and space limitations. Furthermore, measurement noise from pressure sensors may degrade the control performance. We propose an observer-based nonlinear position control with nonlinear coordinate transformation while only using position measurement to improve the position tracking of single-rod EHAs. The proposed method comprises a position controller and an observer. We propose a nonlinear coordinate transform for the controller design. The desired force is designed for the position tracking and boundedness of the internal state. The position controller is designed to track the desired state variables for the EHAs. Meanwhile, a nonlinear observer is proposed in order to estimate a full state using only the position measurement. The stability of the closed-loop system is investigated via an input-to-state stability property. The performance of the proposed method is validated via both simulations and experiments.

Adaptive attitude-tracking control of spacecraft considering on-orbit refuelling

2020 ◽  
pp. 014233122097313
Author(s):  
Yiqi Xu
Keyword(s):  
Tracking Control ◽  
Closed Loop ◽  
Closed Loop System ◽  
Tracking Errors ◽  
Attitude Tracking ◽  
Control Scheme ◽  
Inertia Model ◽  
And Performance ◽  
Attitude Tracking Control ◽  
The Stability

This paper studies the attitude-tracking control problem of spacecraft considering on-orbit refuelling. A time-varying inertia model is developed for spacecraft on-orbit refuelling, which actually includes two processes: fuel in the transfer pipe and fuel in the tank. Based upon the inertia model, an adaptive attitude-tracking controller is derived to guarantee the stability of the resulted closed-loop system, as well as asymptotic convergence of the attitude-tracking errors, despite performing refuelling operations. Finally, numerical simulations illustrate the effectiveness and performance of the proposed control scheme.

Position/force control of robot manipulators using reinforcement learning

2019 ◽  
Vol 46 (2) ◽  
pp. 267-280 ◽  
Author(s):  
Adolfo Perrusquía ◽  
Wen Yu ◽  
Alberto Soria
Keyword(s):  
Reinforcement Learning ◽  
Force Control ◽  
Closed Loop ◽  
Position Error ◽  
Loop System ◽  
Closed Loop System ◽  
Content Type ◽  
Impedance Model ◽  
Impedance Parameters ◽  
The Stability

Purpose The position/force control of the robot needs the parameters of the impedance model and generates the desired position from the contact force in the environment. When the environment is unknown, learning algorithms are needed to estimate both the desired force and the parameters of the impedance model. Design/methodology/approach In this paper, the authors use reinforcement learning to learn only the desired force, then they use proportional-integral-derivative admittance control to generate the desired position. The results of the experiment are presented to verify their approach. Findings The position error is minimized without knowing the environment or the impedance parameters. Another advantage of this simplified position/force control is that the transformation of the Cartesian space to the joint space by inverse kinematics is avoided by the feedback control mechanism. The stability of the closed-loop system is proven. Originality/value The position error is minimized without knowing the environment or the impedance parameters. The stability of the closed-loop system is proven.

scholarly journals Design and Position Control of Overhang-Type Rail Mover Using Dual BLAC Motor

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1000
Author(s):  
Kiwan Cho ◽  
Dong-Hee Lee
Keyword(s):  
Position Control ◽  
Position Sensor ◽  
Position Information ◽  
Position Errors ◽  
Control Scheme ◽  
Speed Range ◽  
Position Controller ◽  
State Position ◽  
Instantaneous Speed ◽  
And Control

This paper presents the design and position control scheme of an overhang-type rail mover system driven by a dual Brushless AC (BLAC) motor with a simple Hall position sensor inside each motor. The overhang-type roller is chosen to reduce the slip between the roller and rail surface due to gravity. The BLAC motors are used to provide smooth translation along the rail and effective turning. Imbalances on any part of the motor and the simplicity of the Hall position sensor can create additional disturbance load, unsteady movement, and position errors. To reduce the sudden moving position error between the two motors, a balancing compensator with a Proportional-Differential (PD) position controller, which is based on the instantaneous speed and position trajectories, is presented. Furthermore, speed and position reference models are designed to compensate for the low Hall sensor resolution in the low-speed range. Therefore, steady-state position errors can then be regulated simply by using the instantaneous speed and position information. Experiments were performed to verify the viability of the proposed system and control. The results show a significant improvement in roller translation along the rail and stopping position accuracy.

Bilateral Parallel Force/Position Teleoperation Control

1999 ◽  
Author(s):  
Keyvan Hashtrudi-Zaad ◽  
Septimiu E. Salcudean
Keyword(s):  
Closed Loop ◽  
Position Control ◽  
Position Tracking ◽  
Task Space ◽  
Closed Loop System ◽  
Teleoperation System ◽  
And Performance ◽  
The Stability ◽  
Teleoperation Systems ◽  
Decoupled Systems

Abstract The application of parallel force/position control to teleoperation systems is considered in this paper. Higher priority is given to position control at the master side and to force control at the slave side of the teleoperation system. The stability and performance of the proposed controller is investigated by analyzing the three decoupled systems obtained from projecting the closed-loop system dynamics onto the slave task-space orthogonal directions. Experimental results demonstrate the excellent force and position tracking performance provided by the new controller.

Position Control of a Floating Ball in a Vertical Air Stream

2017 ◽  
Author(s):  
Shahin S. Nudehi ◽  
Shaffer Dehmlow ◽  
Devin Clark
Keyword(s):  
Feedback Loop ◽  
Position Control ◽  
Transfer Functions ◽  
System Response ◽  
Governing Equations ◽  
Closed Loop System ◽  
Axial Fan ◽  
Air Stream ◽  
Tracking Ability ◽  
The Stability

Quantitative Feedback Theory (QFT) control theory was used to design a control loop in order to provide stability and tracking ability for a ball floating in a jet stream of air. Due to nonlinearity of the system governing equations, a set of linear transfer functions was derived to capture the dynamics of the system. Using this set, a controller and a prefilter were designed that met the stability and tracking performances. The feedback loop was also implemented in an experimental setup consisting of a DC motor, an axial fan, an expansion tank, and a nozzle. The experimental data showed some differences with the simulation results, but the closed-loop system response was satisfactory and the design criteria were met.

scholarly journals Adaptive Output Tracking Control for Nonlinear Systems with Failed Actuators and Aircraft Flight System Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-14
Author(s):  
Chuanjing Hou ◽  
Lisheng Hu ◽  
Yingwei Zhang
Keyword(s):  
Nonlinear Systems ◽  
Tracking Control ◽  
Closed Loop ◽  
High Gain ◽  
Compensation Scheme ◽  
Closed Loop System ◽  
Tracking Errors ◽  
Output Tracking ◽  
Output Tracking Control ◽  
The Stability

An adaptive failure compensation scheme using output feedback is proposed for a class of nonlinear systems with nonlinearities depending on the unmeasured states of systems. Adaptive high-gain K-filters are presented to suppress the nonlinearities while the proposed backstepping adaptive high-gain controller guarantees the stability of the closed-loop system and small tracking errors. Simulation results verify that the adaptive failure compensation scheme is effective.

Command Feedback for Position Control of Hydraulic Machines

2013 ◽  
Author(s):  
Mark Elton ◽  
Ryder Winck ◽  
Wayne Book
Keyword(s):  
Real Time ◽  
Rate Control ◽  
Position Control ◽  
Superior Performance ◽  
Operator Performance ◽  
Hydraulic Machinery ◽  
Position Feedback ◽  
Position Controller ◽  
Time Position ◽  
Slow System

Previous research has shown that operator performance of industrial machines is superior with position control rather than rate control, except for large-workspace and dynamically slow manipulators, which includes most hydraulic machinery. This paper describes an investigation to determine why position control leads to better performance than rate control except for with dynamically slow manipulators, in an effort to increase operator performance of mobile hydraulic equipment. It examines why dynamically slow systems are an exception to the general rule, and proposes a human-machine interface (HMI), called command feedback, that leads to position control having superior performance, even in these exceptional situations. Thirty participants performed five tasks six times using one of five HMIs. A rate and a position controller were used to manipulate a dynamically fast system and a dynamically slow system that was designed to mimic the motion of hydraulic cylinders. A new HMI that provided real-time position feedback to the operator of his/her commanded position was applied to the position controller for the dynamically slow system. Task performance was measured and comparisons were made between position and rate control. The addition of the real-time position feedback to the dynamically slow system resulted in nearly identical performance with both controllers. From these results we conclude that position control is more intuitive for fast systems when human operators do not have the physical capability to control the velocity well with rate control, and that the intuitiveness of rate control for dynamically slow systems results from the lack of position feedback because of the machine’s speed of response. Command feedback can be used to elevate operator performance of hydraulic machinery.

Robust Two-degree-of-freedom Control Based on H∞ Method for PMSM Drive System

2020 ◽  
Vol 13 (4) ◽  
pp. 496-506
Author(s):  
Qixin Zhu ◽  
Lei Xiong ◽  
Hongli Liu ◽  
Yonghong Zhu ◽  
Guoping Zhang
Keyword(s):  
Control System ◽  
Control Theory ◽  
Position Control ◽  
Dynamic Performance ◽  
Servo System ◽  
Degree Of Freedom ◽  
Trade Off ◽  
Standard Design ◽  
Position Controller ◽  
Two Degree Of Freedom

Background: The conventional method using one-degree-of-freedom (1DOF) controller for Permanent Magnet Synchronous Motor (PMSM) servo system has the trade-off problem between the dynamic performance and the robustness. Methods: In this paper, by using H∞ control theory, a novel robust two-degree-of-freedom (2DOF) controller has been proposed to improve the position control performance of PMSM servo system. Using robust control theory and 2DOF control theory, a H∞ robust position controller has been designed and discussed in detail. Results: The trade-off problem between the dynamic performance and robustness which exists in one-degree-of-freedom (1DOF) control can be dealt with by the application of 2DOF control theory. Then, through H∞ control theory, the design of robust position controller can be translated to H∞ robust standard design problem. Moreover, the control system with robust controller has been proved to be stable. Conclusion: Further simulation results demonstrate that compared with the conventional PID control, the designed control system has better robustness and attenuation to the disturbance of load impact.

scholarly journals Consistency of the Empirical Distributions of Navigation Positioning System Errors with Theoretical Distributions—Comparative Analysis of the DGPS and EGNOS Systems in the Years 2006 and 2014

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 31
Author(s):  
Mariusz Specht
Keyword(s):  
Normal Distribution ◽  
Root Mean Square ◽  
Statistical Tests ◽  
Position Error ◽  
Positioning System ◽  
Navigation Systems ◽  
Mean Square ◽  
Positioning Systems ◽  
Position Errors ◽  
System Errors

Positioning systems are used to determine position coordinates in navigation (air, land and marine). The accuracy of an object’s position is described by the position error and a statistical analysis can determine its measures, which usually include: Root Mean Square (RMS), twice the Distance Root Mean Square (2DRMS), Circular Error Probable (CEP) and Spherical Probable Error (SEP). It is commonly assumed in navigation that position errors are random and that their distribution are consistent with the normal distribution. This assumption is based on the popularity of the Gauss distribution in science, the simplicity of calculating RMS values for 68% and 95% probabilities, as well as the intuitive perception of randomness in the statistics which this distribution reflects. It should be noted, however, that the necessary conditions for a random variable to be normally distributed include the independence of measurements and identical conditions of their realisation, which is not the case in the iterative method of determining successive positions, the filtration of coordinates or the dependence of the position error on meteorological conditions. In the preface to this publication, examples are provided which indicate that position errors in some navigation systems may not be consistent with the normal distribution. The subsequent section describes basic statistical tests for assessing the fit between the empirical and theoretical distributions (Anderson-Darling, chi-square and Kolmogorov-Smirnov). Next, statistical tests of the position error distributions of very long Differential Global Positioning System (DGPS) and European Geostationary Navigation Overlay Service (EGNOS) campaigns from different years (2006 and 2014) were performed with the number of measurements per session being 900’000 fixes. In addition, the paper discusses selected statistical distributions that fit the empirical measurement results better than the normal distribution. Research has shown that normal distribution is not the optimal statistical distribution to describe position errors of navigation systems. The distributions that describe navigation positioning system errors more accurately include: beta, gamma, logistic and lognormal distributions.

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