/sci/ - Science & Math

>>9273010
Not to mention, even if we could make a compact fusion reactor that didn't throw out neutrons it would still throw out a fair amount of X-rays.

>>9272726
I'd argue that energy storage isn't that much of an issue so long as you aren't flying. Hydrocarbon fuels have a pretty good energy density, but the issue is that converting them to useful work requires that we have an engine that runs more or less constantly. The power demands for our exoskeleton will not be constant and it is somewhat wasteful to have our engine idling while the user isn't doing much.

Efficiency is another issue. Sure efficiency of energy conversion and actuators are still pretty big issues, but the bigger issue is that we don't understand the dynamics of walking all that well. Big dog and asimo are less efficient than their natural counterparts simply because of the way they're designed. They don't exploit passive dynamics. Moving a brick at the end of a rod back and forth is energetically expensive, but if you add some restoring force all you need to do is add enough energy to overcome losses due to friction.

Now energy conversion efficiency is an issue too. Hydrocarbon fuels have a large energy density, but we can only use 25-30% of this energy as useful work because we have to go through a heat engine. Now what would be ideally is if we could go from chemical to mechanical energy controllably without going to heat. Biological systems do this