Secondary coiled artificial muscle with improved load capacity and reduced energy consumption

Abstract

It is necessary to improve their operability under high loads and reduce the energy consumption required for actuation to effectively use these coiled fiber-type artificial muscles. To address these challenges, a secondary coiled artificial muscle was fabricated by plying two coiled artificial muscles. The secondary coiled artificial muscle exhibited a more compact structure than the conventional primary coiled artificial muscle, resulting in reduced energy consumption required for sufficient heating to induce actuation. The average electric power consumption for actuation was reduced from 0.97 to 0.33 W/g·K. Furthermore, the secondary coiled artificial muscle demonstrated the ability to operate under higher loads and exhibited an improved tensile stroke. The actuation performance of the secondary coiled artificial muscle was further enhanced by applying imbalanced loads across each coiled fiber during the plying process. This approach enabled simultaneous improvements in both tensile stroke and work capacity. Thus, the tensile stroke and work capacity of the secondary coiled artificial muscle, fabricated under imbalanced loading conditions, increased by 1.34 and 1.5 times, respectively, compared to those fabricated under evenly applied loads. These findings indicate that the secondary coiled artificial muscle holds considerable potential for use in various fields.