The pneumatic artificial muscle contraction range is directly determined by the extremum values of braid angle.In theory,the extremum values of braid angles are θmin=0° and θmax=54.73°,respectively.However,the fibre which constitute the pneumatic artificial muscle has geometric shape,so the actual extremum value of braid angle are different from the theory extremum value.The formula of the actual braid angle extremum value was deduced.Through discussion,the method to determine the braid angle extremum value was obtained.

The Modeling method of Mckibben Pneumatic Artificial Muscle is studied.Two main approaches to the force have been developed by researchers,with the first energy modeling,and the second using force profile of surface pressure;under ideal condition,the model of Mckibben Pneumatic Artificial Muscle is the same,with energy method or force method.Considering the limit of the end of Pneumatic Artificial Muscle,the force is reductive,which is certified with energy method or force method.This work is significant for Modeling accurately of Mckibben Pneumatic Artificial Muscle.