Practical Positioning Control Of A One Mass Rotary System

One mass rotary system, is a mechanism that commonly used in industries. Hence for this research, a robust and practical controller design for a one mass rotary system is discussed. The controller is designed and improved based on the conventional structure of the Nominal Characteristic Trajectory Following (NCTF) controller. The continuous motion NCTF (CM-NCTF) controller is proposed for a point to point (PTP) positioning system. The CM-NCTF controller comprising a nominal characteristic trajectory (NCT) and the proportional integral (PI) compensator element. It is designed without knowing the exact model and parameters of the system. The design procedure is applicable, easy to understand and has a simple controller structure. The NCT is constructed from open loop experiment responses while PI compensator is designed experimentally based on the system stability graph.The effectiveness of the proposed controller in positioning and tracking control performance is evaluated experimentally. The experiment was done using various input to examine the controller performance towards parameter variation. While, the controller robustness is evaluated by applying different load into the system to examine system sensitivity towards the disturbance. Then, the effect of positioning, tracking and robustness are compared to the PID and the conventional NCTF controllers. The CMNCTF controller demonstrates good positioning response by having less steady state error, shorter settling time and also small or zero overshoot in comparison to the PID controller. Besides, the CM-NCTF controller performs better tracking control performance when various input frequencies are applied to the system. The proposed controller is proved to have a good positioning, smoother tracking and less sensitivity towards the disturbance. In conclusion, the CM-NCTF controller is more accurate and robust than the PID controller

Fuzzy anti-windup scheme for practical control of point-to-point (Ptp) positioning systems

The Positioning Systems Generally Need A Controller To Achieve High Accuracy, Fast Response And Robustness. In Addition, Ease Of Controller Design And Simplicity Of Controller Structure Are Very Important For Practical Application. For Satisfying These Requirements, Nominal Characteristic Trajectory Following (NCTF) Controller Has Been Proposed As A Practical PTP Positioning Control. However, The Effect Of Actuator Saturation Cannot Be Completely Compensated Due To Integrator Windup Because Of Plant Parameter Variations. This Paper Presents A Method To Improve The NCTF Controller For Overcoming The Problem Of Integrator Windup By Adopting A Fuzzy Anti-Windup Scheme. The Improved NCTF Controller Is Evaluated Through Simulation Using Dynamic Model Of A Rotary Positioning System. The Results Show That The Improved NCTF Controller Is Adequate To Compensate The Effect Of Integrator Windup

Dynamic weighted idle time heuristic for flowshop scheduling

The constructive heuristic of Nawaz, Enscore and Ham (NEH) has been introduced in 1983 to solve flowshop scheduling. Many researchers have continued to improve the NEH by adding new steps and procedures to the existing algorithm. Thus, this study has developed a new heuristic known as Dynamic Weighted Idle Time (DWIT) method by adding dynamic weight factors for solving the partial solution with purpose to obtain optimal makespan and improve the NEH heuristic. The objective of this study are to develop a DWIT heuristic to solve flowshop scheduling problem and to assess the performance of the new DWIT heuristic against the current best scheduling heuristic, ie the NEH. This research developed a computer programming in Microsoft Excel to measure the flowshop scheduling performance for every change of weight factors. The performance measure is done by using n jobs (n=6,10 and 20) and 4 machines. The weight factors were applied with numerical method within the range of zero to one. Different weight factors and machines idle time were used at different problem sizes. For 6 jobs and 4 machines, only idle time before and in between two jobs were used while for 10 jobs and 20 jobs the consideration of idle time was idle time before, in between two jobs and after completion of the last job. In 6 jobs problem, the result was compared between DWIT against Optimum and NEH against Optimum. While in 10 jobs and 20 jobs problem the result was compared between DWIT against the NEH. Overall result shows that the result on 6 and 10 jobs problem the DWIT heuristic obtained better results than NEH heuristic. However, in 20 jobs problem, the result shows that the NEH was better than DWIT. The result of this study can be used for further research in modifying the weight factors and idle time selections in order to improve the NEH heuristic

Practical Control for Two-Mass Positioning Systems in Presence of Saturation

 The precision positioning systems generally need a good controller to achieve a fast response, high accuracy and robustness. In addition, ease, simplicity of controller design structure and high motion control performance are very important for practical applications. For satisfying these requirements, nominal characteristic trajectory (NCT) with proportional integral (PI) and notch filter (NF) as a compensator has been proposed as a practical control method for two-mass rotary PTP positioning systems. However, the effect of the actuator saturation cannot be completely compensated due to integrator windup when the object parameter varies. This paper presents a method to further improve nominal characteristic trajectory following (NCTF) controller to overcome the problem of integrator windup by adopting PI anti-windup schemes. The improved NCTF controller is evaluated experimentally using two-mass rotary positioning systems. The effect of the design parameters on the robustness of the improved NCTF with anti-windup integrator controller is evaluated and compared with NCTF without anti-windup integrator and the equivalent PID controller. The results show that the improved NCTF controller is effective to compensate the effect of integrator windup

Fuzzy antiwindup schemes for NCTF control of Point-Topoint (PTP) positioning systems

The positioning systems generally need a controller to achieve high accuracy, fast response and robustness. In addition, ease of controller design and simplicity of controller structure are very important for practical application. For satisfying these requirements, NCTF (nominal characteristic trajectory following) controller has been proposed as a practical PTP positioning control. However, the effect of actuator saturation can not be completely compensated due to integrator windup because of plant parameter variations. This study presents a method to improve the NCTF controller for overcoming the problem of integrator windup by adopting fuzzy anti-windup schemes. Two fuzzy antiwindup schemes based on Mamdani and Takagi-Sugeno fuzzy system are developed and evaluated their effectiveness. The improved NCTF controller with the proposed fuzzy anti-windup schemes is evaluated through simulation using dynamic model of a rotary positioning system. The results show that the improved NCTF controller with Takagi-Sugeno-based fuzzy windup is the best scheme to compensate for the effect of integrator windup

Design And Analysis On The Robust Control Of A X-Y Ballscrew Mechanism

This thesis presents the design and analysis on the robust control of a X-Y ballscrew mechanism. In this research, a practical and robust controller for positioning control is discussed. The Continuous Motion Nominal Characteristic Trajectory Following (CM NCTF) controller is investigated in this research for tracking motion of an AC driven X-Y ballscrew mechanism. The CM NCTF controller has a simple control structure and straightforward design procedure that does not require an exact model parameter of a plant. In order to enhance the accuracy of the control system, a suitable input signal is designed to make sure the X-Y ballscrew mechanism attenuate smoothly in the deceleration motion. The CM NCTF controller consists of a Nominal Characteristic Trajectory (NCT) and a Proportional and Integral (PI) compensator. The NCT is constructed using the open-loop experimental responses while the PI compensator is designed based on a practical stability limit obtained experimentally. The CM NCTF controller has been evaluated in tracking motion performance. In order to examine the adaptability of the controller to the change of the input, experiments with various inputs is carried out. Besides that, the robustness of the controller is validated through the change of the load of the system. In order to examine the usefulness of the CM NCTF controller, a PI-D controller that has a similar control structure is designed and compared. The tracking performance of the CM NCTF controller is evaluated in maximum peak error Emax, percentage of error Epercent, and root mean square of error Erms. Emax is the difference between the output peak and the reference input, and Epercent is the percentage of the peak error with respect to the reference input. The experimental results proved that the CM NCTF controller has demonstrated better positioning response than the conventional NCTF controller and the PI-D controller by showing a two times smaller motion error. The robustness of the CM NCTF controller is clarified using X-axis, which has heavier load than the Y-axis. The experimental results have again proved that the CM NCTF controller demonstrates better tracking performance than the conventional NCTF controller and the PI-D controller in X-axis. As a conclusion, the CM NCTF controller has better positioning performance as compared to the conventional NCTF controller and PI-D controller. In future, the contour motion for X-axis and Y-axis will be done to evaluate accuracy of the controller. Besides that, the robustness performance in term of change of disturbance force will be considered

CONTINUOUS MOTION NOMINAL CHARACTERISTIC TRAJECTORY FOLLOWING CONTROL FOR POSITION CONTROL OF AN AC DRIVEN X-Y BALL SCREW MECHANISM

AC servo mechanisms are widely used in industrial application due to its advantages in higher efficiency, less maintenance, and smoother operation than DC servo mechanism. However, AC servomechanism frequently suffers from its inherently non-linear characteristics and more difficult to be controlled in positioning applications. A general step input easily drove the mechanism and stop smoothly in the open-loop environment, however, it is not the same for AC driven ball screw mechanism. Hence, the contributions in this paper are: (1) the realization of the practical control method - continuous motion nominal characteristic trajectory following (CM NCTF) control to an AC driven ball screw mechanism, (2) the design of a suitable input signal that produces sufficient rapid and smooth response during deceleration motion in the open-loop experiment. The open-loop responses used to construct nominal characteristic trajectory (NCT) are important because it significantly affects the reference following characteristic of the control system. The experimental evaluations were carried out for CM NCTF control system and PI-D control system. The results show that the designed input signal has successfully produced rapid and smooth open-loop responses during deceleration that benefit the reference position near NCT origin. Besides that, the CM NCTF control system that designed with the newly constructed NCT has demonstrated better positioning results than the PID controller with almost 10 times of motion error reduction for Y-axis for both amplitudes of 5 mm and 10 mm respectively