Electrostrictive polymer artificial muscle actuators

TLDR

Robotic and teleoperated systems demand high mobility and dexterity that current actuators cannot easily deliver; natural muscle provides high energy density, speed, and stroke, and electrostrictive polymer dielectrics with compliant electrodes can emulate muscle-like actuators achieving up to 30 % strain and 1.9 MPa pressure. A simple linear elastic model predicts EPAM actuator performance from material properties and load conditions. Polyurethane and silicone EPAM actuators achieve higher specific energy than electromagnetic, electrostatic, piezoelectric, and magnetostrictive actuators; a spherical joint for a snake‑like manipulator and a rotary motor using EPAM elements have been demonstrated, with the motor delivering 19 mNm/g torque and 0.1 W/g power, and an improved motor could surpass electric motors in specific power and torque.

Abstract

Many new robotic and teleoperated applications require a high degree of mobility or dexterity that is difficult to achieve with current actuator technology. Natural muscle is an actuator that has many features, including high energy density, fast speed of response, and large stroke, that are desirable for such applications. The electrostriction of polymer dielectrics with compliant electrodes can be used in electrically controllable, muscle-like actuators. These electrostrictive polymer artificial muscle (EPAM) actuators can produce strains of up to 30% and pressures of up to 1.9 MPa. The measured specific energy achieved with polyurethane and silicone polymers exceeds that of electromagnetic, electrostatic, piezoelectric, and magnetostrictive actuators. A simple model using linear elastic theory can predict EPAM actuator performance from mechanical and electrical material properties and load conditions. A spherical joint for a highly articulated (snake-like) manipulator using EPAM actuator elements has been demonstrated. A rotary motor using EPAM actuator elements has been shown to produce a specific torque of 19 mNm/g and a specific power of 0.1 W/g. An improved EPAM motor could produce greater specific power and specific torque than could electric motors.