Smodified-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 inherencompliant safety,compactness,dust-resistant and 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 challengeable 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. thereforethis research aims to highlight a practical and simple control framework capable oproviding ameliorated compensation towards the non-linearities in 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 othe 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 testbed – 1dof pma system; in point-to-point motion that driving in severastep 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% osettling time as compared with the conventional pid control. overall,the experimentaresults show that the proposed controller is capable of demonstrating a satisfactory transient,with better overshoot reduction characteristic and faster settling time; and robusperformance under default and in the presence of the change of load,in comparison with the conventional pid control. © 2017 penerbit utm press. all rights reserved.