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178 CHAPTER SEVEN
system can adapt, problems will arise. The spy-hopping interval may remain too large
to effectively sample the sped-up environment. If limits exist on the rate of change in
the environmental processes, then the adaptive control system can be designed to keep
up. But if no definitive boundaries exist for these processes, be wary of adaptive con-
trol loops within the robot. It might be better just to waste the extra energy and let the
control system run at the fast rate, rather than risk a control system problem.

Software Considerations for

Energy Control

As discussed before, only hardware can conserve energy since it’s the only consumer.
Most of the hardware features capable of conserving energy will probably be under the
direct control of the software. Many techniques for using software to save energy bear
mentioning.

OPERATING SYSTEM
We’ve already discussed some of the operating system (OS) hooks that can be used to
conserve power. By and large, the very presence of an OS is antithetical to the proper
functioning of a parsimonious energy conservation system. We won’t discuss this much
further since each OS will have its own documentation for such matters, but be careful
that the OS properly supports the energy conservation states of the processor that is run-
ning the OS. If the OS has not been properly ported to the processor, or if the OS does
not support energy conservation, then consider another one.
One of the key features of an OS that we’ve mentioned is the handling of the soft-
ware environment. The OS must be capable of storing and retrieving software environ-
ments so it can survive power failures. During the initial system engineering of the
robot, we must decide what the implications of power failures are. If the robot must be
able to survive a brief interruption of power, then special hardware and software con-
siderations must be made. We’ll discuss these in the section on power failures.

ALGORITHMS

We can tailor algorithms to conserve power. The central idea is that each individual
operation in a control algorithm, each and every executed instruction step, consumes