  We present a novel pneumatic augmentation to traditional electric
motor-actuated legged robot to increase intermittent power density to perform
infrequent explosive hopping behaviors. The pneumatic system is composed of a
pneumatic pump, a tank, and a pneumatic actuator. The tank is charged up by the
pump during regular hopping motion that is created by the electric motors. At
any time after reaching a desired air pressure in the tank, a solenoid valve is
utilized to rapidly release the air pressure to the pneumatic actuator (piston)
which is used in conjunction with the electric motors to perform explosive
hopping, increasing maximum hopping height for one or subsequent cycles. We
show that, on a custom-designed one-legged hopping robot, without any
additional power source and with this novel pneumatic augmentation system,
their associated system identification and optimal control, the robot is able
to realize highly explosive hopping with power amplification per cycle by a
factor of approximately 5.4 times the power of electric motor actuation alone.
