This is actually a 3D printer, but [elevate the rails and] replace the print head with a couple of general purpose robotic arms and you’ve got the makings of a gardening robot.
Robots clean rivers and sort waste, monitor ecosystems, and inspect renewable-energy infrastructure. But even the greenest robot has an environmental footprint.
EPFL engineers have designed acoustic cavities that convert sound waves into thrust, propelling small robots and ultralight aerial vehicles without on-board actuators or electronics.