A Trapezoidal Velocity Profile Generator for Position Control Using a Feedback Strategy

Position control is usually achieved using a position controller and a profile generator. The profile generator produces a desired position trajectory from a position reference and predefined profiles. The position controller forces the actual position to trace the generated position trajectory. A time-based profile generator is the most famous profile generator due to its capability of generating various profiles. However, time base difference in analysis and implementation causes a steady-state error. In order to remove the steady-state error, this paper proposes a novel profile generator for a trapezoidal velocity profile generation. The proposed generator is based on a cascaded P-PI position controller which is designed to trace the position reference. A dynamic range limiter is adopted to provide the acceleration and velocity restrictions which are basic functions for generating the trapezoidal profile. In spite of these restrictions, it cannot make a desired velocity profile only using the limiter because deceleration point is inaccurate. To adjust the deceleration point, a feedback compensator is designed which requires the velocity of the deceleration point. The velocity of the deceleration point is estimated from the initial position error. The compensator moves the deceleration point to the appropriate point which can generate the desired velocity profile. The proposed profile generator can remove the steady-state error, and the position response can be easily adjusted to be either overdamped or underdamped by selecting the two gains appropriately. Several experimental results are presented to verify the usefulness of the proposed generator.

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A Simple Switching Control Structure for Improving the Steady-State Error of a Full-Digital Water-Hydraulic Cylinder Position Control

Proceedings of the 4th Asia International Symposium on Mechatronics ◽

10.3850/978-981-08-7723-1_p231 ◽

2010 ◽

Cited By ~ 1

Author(s):

Jyh-Chyang Renn ◽

Shigeru Ikeo ◽

Chin-Yi Cheng

Keyword(s):

Steady State ◽

Position Control ◽

Control Structure ◽

Hydraulic Cylinder ◽

Switching Control ◽

Water Hydraulic ◽

State Error

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Robot torque and position control using an electrorheological actuator

Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering ◽

10.1243/0959651981539424 ◽

1998 ◽

Vol 212 (3) ◽

pp. 229-238 ◽

Cited By ~ 3

Author(s):

D J Brookfield ◽

Z B Dlodlo

Keyword(s):

Steady State ◽

Applied Field ◽

Position Control ◽

Open Loop ◽

Settling Time ◽

Time Varying ◽

Control Loop ◽

Loop Transfer Function ◽

Non Linear ◽

State Error

An electrorheological (ER) clutch driven from a constant speed motor provides a steady torque independent of shaft angle and can be controlled by control of the applied field. Such an actuator avoids the ‘cogging’ variation in torque observed in d.c. servo-motors and is thus well suited to robot control applications, particularly in view of the very rapid time response of ER clutches (≍ 10−3 s). However, the relationship between applied field and torque is difficult to model, being both non-linear and time varying. Whereas the non-linearity can be shown to be relatively small, the time-varying characteristic has remained a problem. In most controlled plants, a non-linear or time-varying characteristic can be mitigated by providing a closed control loop around the plant. A PID (proportional plus integral plus derivative)-based torque controller was developed and tested. This was shown to be stable with at least critical damping and to exhibit low steady state error. Design of the controller was facilitated by the identification of the open-loop transfer function of the ER actuator. The ER actuator with torque feedback was used to position a small robot link. A second PID control loop responding to the error in the link position and tuned using the standard Ziegler and Nichols method was designed and tested. A steady state error of less than 0.75 mm was achieved with a 2 per cent settling time of 2.0 s. Finally, the link position was controlled using a single-loop controller with no torque feedback and a similar steady state error achieved with a 2 per cent settling time of 1.4 s. It is argued that the ER torque actuator is ideally suited to the actuation of robot joints where precise smooth movement is required.

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Modeling and Its Error Analysis for Load-Sensing Steering System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.694-697.678 ◽

2013 ◽

Vol 694-697 ◽

pp. 678-682

Author(s):

Hai Fang Wang ◽

Xiao Guang Ren ◽

Yu Rong

Keyword(s):

Steady State ◽

Transfer Function ◽

Input Signal ◽

Position Control ◽

Steering System ◽

Force Balance ◽

Energy Effect ◽

Load Sensing ◽

Hydraulic Steering ◽

State Error

Load-sensing hydraulic steering system is universally used in wheeled machinery for good steering regulation performance and obviously saving energy effect. The load-sensing hydraulic steering system is present, and it is considered to be a mechanical and hydraulic position control system. The flow continuity equation and force balance equation of steering system is established, the transfer function of load-sensing hydraulic steering system is obtained, the system steady-state error caused by the typical input signal and load input signal on the basis of transfer function. The main parameters affecting the steady-state error are got, and it provides theoretical support for designing and improvement of load-sensing hydraulic steering system.

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An anti-windup rate-varying integral control applied to electromechanical actuator

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406214539305 ◽

2014 ◽

Vol 229 (4) ◽

pp. 692-702

Author(s):

Mohammad Reza Sabaapour ◽

Esmaeel Khanmirza ◽

Siamak Ghadami

Keyword(s):

Steady State ◽

Trajectory Tracking ◽

Position Control ◽

Nonlinear Modeling ◽

External Disturbance ◽

Error Signal ◽

Integral Control ◽

Electromechanical Actuator ◽

Good Agreement ◽

State Error

This paper introduces a novel integral-based controller to correct steady-state error as well as to improve trajectory tracking in position control of a rotary actuator. For this aim, linear and nonlinear modeling of a rotary electromechanical actuator via conventional P-D controller has been described followed by investigation of nonlinear element's effects. The model has very good agreement with experimental results. Then, for trajectory tracking improvement and especially to reduce steady-state error induced by external disturbance, different integral based controllers such as PID, PI-D, and I-PD have been considered. Moreover, the problem of integrator saturation (integral wind-up) has been solved by modified rate varying integral method. It has been showed that a PI-D controller with modified rate varying integral can best match controlling requirements, as well as having enough simplicity for analogue implementation. Also, as a new method, it was suggested that for rate-varying integral calculation, the error rate signal could be replaced by error signal. Doing so, not only former advantages were hold, but more simplicity in controller implementation was gained. Simulation results have shown the effectiveness of the proposed method.

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Angular Position Control of Fluid-Driven Spindle

Volume 10: Mechanical Systems and Control, Parts A and B ◽

10.1115/imece2009-11075 ◽

2009 ◽

Author(s):

Yohichi Nakao ◽

Naoya Asaoka

Keyword(s):

Mathematical Model ◽

Control System ◽

Steady State ◽

Disturbance Observer ◽

Position Control ◽

Angular Position ◽

Experimental Results ◽

The Mathematical Model ◽

Position Control System ◽

State Error

A precise spindle is essential to achieve precision machining, such as diamond turning. A fluid driven spindle supported by hydrostatic bearings was thus designed and tested. A feature of the spindle is that several flow channels are designed in its rotor so that driving torque can be generated by supplying pressurized flow into the channels. Rotational speed of the spindle can be controlled by the flow rate. In addition, the rotational direction of the spindle can be controlled by switching supply ports. Thus angular position control of the spindle is achieved by designing appropriate feedback controller. In the present paper, mathematical model of the spindle was thus derived in order for designing an angular position control system. Then spindle characteristics calculated by the mathematical model were compared with experimental results. Furthermore, the angular position control system that has a disturbance observer in its feedback loop was designed based on the mathematical model. The performance of the designed control system was experimentally investigated through the step response. Experimental results verified that the designed controller minimizes the steady state error of angular position of the spindle. Consequently, the steady state error was comparable with the resolution of the rotary encoder, 0.018 degree. In particular, the experimental results indicated that the disturbance observer effectively reduced the influence of various load torque on the angular position of the spindle.

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Extention of Strongly Stable GPC for Improvement of Steady State Error

IEEJ Transactions on Electronics Information and Systems ◽

10.1541/ieejeiss.138.498 ◽

2018 ◽

Vol 138 (5) ◽

pp. 498-505 ◽

Cited By ~ 1

Author(s):

Toyoaki Tanikawa ◽

Tomohiro Henmi ◽

Akira Inoue ◽

Akira Yanou ◽

Shinich Yoshinaga

Keyword(s):

Steady State ◽

State Error

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

Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) ◽

10.2174/2352096512666190319164237 ◽

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.

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