In nature, you're not likely to ever see a bird get a piggyback ride from a cockroach and then take off from its back. But in the world of bio-inspired robotics, such things can and do happen. Researchers from the UC Berkeley's Biomimetic Millisystems Lab have successfully demonstrated a cooperative launching system that puts a lightweight ornithopter on the back of its VelociRoACH robotic carpet crawler for a short run before the H2Bird takes to the air.
The Lab's 10-cm (4-in) long, 32 g (1.1 oz) six-legged robot roach has a top speed of 2.7 meters per second (which is quick, but not the fastest roach at Berkeley, that honor is reserved for the X2 version of the VelociRoACH – which can be seen in this video) and is capable of carrying a payload of up to 120 g (4.2 oz). The brains of the beast are represented by an ImageProc 2.5 micro-controller that's home to a microprocessor, IEEE 802.15.4 radio and motor drivers. It has two brushed DC motors in separate gear boxes to independently drive the legs.
The 13.2 g (0.47 oz) H2Bird micro-aerial vehicle features an ImageProc 2.4 controller and the power train from an i-Bird RC flying bird. Its roughly bird-like shape is made of clear plastic stretched over a carbon fiber-reinforced frame, with a wing span of 26.5 cm (10.4 in). It flaps its four wings for take off and flight and is able to stay aloft for about 2.5 minutes before its 90 mAh battery needs topping up. The tail rotor keeps yaw in check while a servo-driven elevator takes care of pitch.
After conducting tests to determine the precise angle of attack and velocity needed to get the bird in the air, the roach was fitted with a special launch cradle, higher at the front than at the back, and test runs conducted. You can see the results in the video below.
With the robotic flapper on its back, the VelociRoACH motors were found to use up to 24.5 percent more power. But just having the bird in its cradle resulted in the ambulating carrier bot running with more stability, reducing the variance in pitch and roll velocity by as much as 90 percent. The researchers also discovered that having the bird flap its wings slightly while being carried helped increase the average velocity of the robot roach by 12.7 percent.
The roboticists intend to continue the cooperative launching experiments with the aim of getting the bird to take off without human intervention.
Source: Biomimetic Millisystems Lab
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