RECONFIGURATION OF MULTI-STAGE TENSEGRITY STRUCTURES USING INFINITESIMAL MECHANISMS

Abstract

THE USE OF TENSEGRITY STRUCTURES IN SOFT ROBOTICS HAS SEEN AN INCREASED INTEREST IN RECENT YEARS THANKS TO THEIR MECHANICAL PROPERTIES, BUT THE CONTROL OF THESE SYSTEMS REMAINS AN OPEN PROBLEM. THIS PAPER PRESENTS A RECONFIGURATION STRATEGY FOR ACTUATED MULTI-STAGE TENSEGRITY STRUCTURES. THE ALGORITHM WORKS ON THE PRINCIPLE OF USING THE INFINITESIMAL MECHANISMS OF THE STRUCTURE TO GENERATE A PATH OF POSITIONS ALONG WHICH A MULTI-STAGE TENSEGRITY STRUCTURE CAN CHANGE ITS SHAPE WHILE MAINTAINING THE SELF-EQUILIBRIUM. COMBINING THE FORCE DENSITY METHOD WITH A MARCHING PROCEDURE, THE SOLUTION TO THE EQUILIBRIUM PROBLEM IS GIVEN BY A SET OF DIFFERENTIAL EQUATIONS THAT DEFINE THE KINEMATIC CONSTRAINTS OF THE STRUCTURE. BEGINNING FROM AN INITIAL STABLE POSITION, THE ALGORITHM CALCULATES A SMALL DISPLACEMENT UNTIL A NEW STABLE CONFIGURATION IS REACHED, AND RECURRENTLY REPEATS THE PROCESS DURING A GIVEN INTERVAL OF TIME. BY MEANS OF THREE NUMERICAL EXAMPLES, WE SHOW THE EFFICACY OF OUR ALGORITHM FOR RECONFIGURING A TWO-STAGE TENSEGRITY MAST ALONG DIFFERENT DIRECTIONS.