Artificial Muscle and Biomimetic Robots

SRI is applying its electroactive polymer artificial muscle (EPAM) actuators to small, mobile robots and micro-machine applications. In 2004, SRI spun off its patented electroactive polymer technology to Artificial Muscle, Inc. to commercialize the technology in electronic and industrial applications. SRI and AMI continue to develop the technology for many applications and markets.

EPAM actuator

The advantage of SRI’s artificial muscle robots is that by using biomimetics—the imitation of certain performance characteristics of natural muscle such as high strain, high peak power, and high compliance—it allows for the robots to mimic the dexterity and mobility of natural creatures.

In addition, SRI’s research in elastomeric polymer materials has demonstrated promise for a variety of actuator and electric power generation applications. The key design feature of devices based on these materials is the use of compliant electrodes that enable polymer films to expand or contract in the in-plane directions responding to applied electric fields or mechanical stresses.

SRI's EPAM robots and applications

EPAM (1992-present)

FLEX  (1999-2003)

Skitter (2001-2002) 

MERbot (2002-2004)

Watch some of these technologies in action (.avi videos):

- Spring roll actuator

- FLEX

- Skitter

- MERbot

Learn more about SRI's electroactive polymer transducers here.

EPAM technology

(1992-present)

Using electroactive polymers, which expand when a signal is applied (in opposite fashion to natural muscle), SRI broke new ground by enabling the creation of robots inspired by nature’s own design. Rubbery actuators expand when a voltage is applied, providing compliant, lightweight, and efficient direct-drive actuation that is unparalleled in strain, speed of response, and energy density. SRI has demonstrated numerous EPAM-enabled walking and jumping robots, as well as robots that emulate snakes, fish, and birds. These artificial muscles are much smaller than the servos and motors of conventional robots, allowing designs that may achieve the size and forms of geckos, hummingbirds, and cockroaches. Other robotic applications for this muscle-mimicking technology include robotic grippers, animatronics, and haptic feedback.

Learn more about SRI's electroactive polymers.

FLEX

(1999-2003)

FLEX was the first self-contained walking robot powered by electroactive polymers. Based loosely on the walking gaits of cockroaches, each of its six legs used two EPAM roll actuators to move up and down, and back and forth. The largest EPAM-enabled robot to date at 470 g, FLEX moved at speeds greater than 12 cm/s, actuating its legs at frequencies up to 10 Hz.

Skitter

(2001-2002)

To demonstrate the multifunctional ability of EPAM to act as both structure and actuator, Skitter used a single roll actuator for each of its six legs. Based on the biomimetic principles of the Sprawlita robot built at Stanford University, Skitter replaced Sprawlita's pneumatic legs (which require an external air supply) with electrically actuated EPAM. Passive compliance in rotation of each leg allowed Skitter to efficiently negotiate obstacles in its path without requiring the complexity of an additional actuator or sensory feedback.

MERbot

(2002-2004)

The Multifunctional Electroelastomer Rolls robot (MERbot) showed how advanced actuation methods can greatly simplify robot design by replacing legs made out of many parts (such as links, joints, and actuators) with a single, flexible bending actuator that is both the structure and actuator. The resulting hexapod robot consists of little more than the six legs and the plate to which they are attached. No existing actuator technology provided the flexibility and range of motion needed for the MERs.