Positioning Control Of A 1-DOF Pneumatic Muscle Actuator (PMA) System With Modified PID Plus Feedforward Controller

The pneumatic muscle actuator (PMA) is a novel actuator which carries numerous advantages such as high strength and power/weight ratio, low cost, compact, clean and easy to maintain features. However, pneumatic muscle actuator has notable nonlinear characteristics, which makes it difficult to control. The purpose of this research is focused on experimental system development and parameter characterization of phenomenological modelling for commercially available Festo Fluidic Muscle Actuator. The model and parameters obtained from the characterization are validated in simulation and experimental platform. The major part of the research is focused on the framework of the modified PID plus feedforward control system, and its effectiveness in a 1 degree-of-freedom PMA system is experimentally demonstrated in comparison with a classical PID controller. The overall control system comprises of a feedforward controller and a modified PID controller in the feedback loop which designed based on the exact PMA system characteristics. The design procedure of the modified PID plus feedforward controller is practical and features easy design procedures. The usefulness and advantages of the proposed controller are shown via positioning and tracking motion experimental studies. Besides, this study also highlights the robustness of the modified PID plus feedforward controller by examining its performance in point-to-point and tracking motions in the presence of extra mass. In the robustness performance, the modified PID plus feedforward controller is compared with a classical PID control systems. The comparative experiments results illustrate that modified PID plus feedforward controller shows the significant motion performances as compared to the PID controller by maintaining steady state error between ±50μm. The framework used to develop the proposed controller is generally enough for further investigation in PMA motion control system, further improvement in terms of positioning accuracy and tracking motion could extend th

Positioning Control Of Ball Screw System Driven By DC Motor

This paper presents the comparison of positioning control between conventional PID controller and fuzzy PID controller. The controllers are applying into the ball screw system driven by DC motor to observe and analyze the change of the positioning output responses. The DC motor is used because it is easy to setup and control, has precise rotation and most importantly is low cost. As for ball screw mechanism itself, has smooth motion, not easy to wear out and high mechanical efficiency. The problem is arise when the used of conventional PID controller in the ball screw system driven by DC motor shows less adaptability to the changes of system parameter. Therefore, the objective of this project is to design an adaptive fuzzy PID controller to overcome the limitation of conventional PID controller. The performances between the conventional PID controller and fuzzy PID controller will be compared in order to validate the robustness of the fuzzy PID controller. So this project is to compare the robustness of two proposed controllers by comparing the results of ball screw table position when the parameter mass of load is set to vary. The experiment is started with designing the algorithms of fuzzy PID control and conventional PID controller, then the designed algorithm is applied onto the experimental that has been setup. The performances especially the transient response and steady state error between the controllers will be collected and compared by conducting the point to point positioning, tracking and variation of load weight experiments

Modified-PID Control With Feedforward Improvement For 1-Degree-Of-Freedom Pneumatic Muscle Actuated System

Over the past decade, pneumatic muscle actuators (PMA) has been receiving much attention due to the favorable advantages that PMA has to offer such as inherent compliant safety, compactness, dust-resistantand powerful, especially for rehabilitation application. However, the highly non-linear phenomenon exhibited by PMA poses a challenge in positioning control of the mechanism. Due to the highly nonlinear properties of the PMA system, it is difficult and challenge able to model the system accurately. Many advanced controls have been proposed, however, majority of them requires accurate model parameters for the design and/ or deep understanding of control theory. Therefore, this research aims to highlight a practical and simple control framework capable of providing ameliorated compensation towards the non-linearitiesin a PMA positioning system. The proposed controller is a combination of a modified PID control incorporated with a model-based feed-forward element. The modified PID control is cascaded with a modeled-nonlinear function and a linearizer that works to compensate the influence of the nonlinearities. The design procedure of the proposed control remains simple and none of the known parameter is required. The proposed controller is verified experimentally using the constructed test bed –1DOF PMA system;in point-to-point motion that driving in several step heights(5 mm, 10 mm, 20 mm, and 30 mm). At the step height of 30 mm, the proposed control has demonstrated three times smaller of overshoot and the reduction of 39% of settling time as compared with the conventional PID control. Overall, the experimental results show that the proposed controlleris capable of demonstrating a satisfactory transient, with better overshoot reduction characteristic and faster settling time; and robust performance under default and in the presence of the change of load, in comparison with the conventional PID control