  Mobile robots are often needed for long duration missions. These include
search and rescue, sentry, repair, surveillance and entertainment. Current
power supply technology limit walking and climbing robots from many such
missions. Internal combustion engines have high noise and emit toxic exhaust
while rechargeable batteries have low energy densities and high rates of
self-discharge. In theory, fuel cells do not have such limitations. In
particular Proton Exchange Membrane (PEMs) can provide very high energy
densities, are clean and quiet. However, PEM fuel cells are found to be
unreliable due to performance degradation. This can be mitigated by protecting
the fuel cell in a fuel-cell battery hybrid configuration using filtering
electronics that ensure the fuel cell is isolated from electrical noise and a
battery to isolate it from power surges. Simulation results are presented for a
HOAP 2 humanoid robot that suggests a fuel cell powered hybrid power supply
superior to conventional batteries.
