In the past small robots like the RoboBee developed at Harvard were packed with hard parts that were fragile and could be destroyed in an impact with a wall or other robot. The scientists behind RoboBee have developed a new and resilient version of the robot that is powered by soft artificial muscles that can crash into things without being damaged.
The flying robot is the first microbot to achieve controlled flight using soft actuators. Researchers say that many people in the field of microrobots have been skeptical that soft actuators could be used for flying robots because the power density of such actuators has been too low. Soft actuators are also difficult to control. The team says that its actuator has high enough power density and the controllability needed to achieve hovering flight.
The issue of power density was solved by building on research into electrically-driven soft actuators developed by David Clarke at Harvard. The actuators are made using dielectric elastomers. That material is soft with good insulating properties and deforms when an electric field is applied. With improved electrode conductivity, the team was able to operate the actuator at 500 hertz, which is on par with rigid actuators used in similar robots.
The team overcame another challenge by using a lightweight airframe with a piece of vertical constraining thread to prevent the actuator from buckling. The team says that the soft actuators can be easily assembled and replaced in small scale robots. Several different models of RoboBee were built.
A two-wing model was able to take off from the ground but lacked additional control. A four-wing version could fly in a cluttered environment and overcome multiple collisions in a single flight. The version of RoboBee that was able to demonstrate controlled hovering flight was an eight-wing, four-actuator model. The team is currently working to increase efficiency for soft robots.