Development of a McKibben artificial muscle using a shape-memorypolymer

摘要

When McKibben artificial muscle actuators are applied to robotic joints, the joints are driven by pairs of actuatorslocated antagonistically to increase the joint stiffness. However, the force for shape fixity is not large. Therefore, theobjective of this study is to develop a McKibben artificial muscle using a shape-memory polymer (SMP). SMPs can bedeformed above their glass transition temperature ( T_g)by applying a small load. They maintain their shape after theyhave been cooled to below T_g. They then return to the predefined shape when heated above T_Exploiting thesecharacteristics, we coated the braided mesh shell of a commercial McKibben artificial muscle and made a prototype ofthe actuator using the SMP. When this new actuator is warmed above T_g, the SMP deforms. Then, when internalbladder is pressurized, the actuator shortens and/or produces a load. After the actuator becomes the desirable length, theactuator is cooled to below Tg and the SMP is fixed in a rigid state even without the air supply. Consequently, thisactuator can maintain its length more rigidly and accurately. The experimental results conducted on this prototypeconfirm the feasibility of this new actuator.