So, the USC team made lighter, better actuators. The RoboBee uses bimorph actuators, made up of three layers. The two outer piezoelectric layers contract alternately via a signal, and this in turn bends the inner layer back and forth, thus flapping it like an insect wing. In contrast, the USC team created unimorph actuators. These employ just one strip of piezoelectric material which move the passive layer back and forth. The resulting flight control improvements means that the Bee+ is able to following a path and avoid obstacles. And because these unimorph actuators are simpler, they’re also cheaper to build.