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Subject: 
SHRIMP power
Newsgroups: 
lugnet.robotics
Date: 
Tue, 9 Oct 2001 02:59:40 GMT
Viewed: 
439 times
  
OK, I (finally) have a SHRIMP platform which doesn't tear itself apart. Now to
the problem of power. The problem is that I don't have enough, of course. Have
any of the other SHRIMP builders encountered this?

The setup:
Each of the six wheels uses a geared motor to drive a worm gear which drives a
24-tooth gear attached to the axle of a motorcyle wheel. In other words, I'm
geared down 24:1 using a worm gear. I'm driving all six motors off a single
output port of the RCX. The RCX is powered by 6 AA rechargeable alkaline
batteries, which are fully charged (but far from new). I also have the added
mass of two geared motors for steering. I have enough power to climb over a
single step as high as 3/4 of the wheel diameter, but not to climb over two
stairs of the same height. When I use similar batteries directly from a battery
pack (but keeping the SHRIMP's weight constant), I can climb two stairs. Early
tests indicate that even this doesn't have enough power to climb an obstacle of
1.5 times the wheel diameter.

Questions:
Is my problem in the mechanical design (not geared low enough? wasted energy?)
or in the power supply? I don't relish the idea of buying disposable alkaline
batteries in bulk, or of tethering my robot to a wall wart.

No power would be gained in splitting the motors between two output ports,
right? (Not that I have the ports to spare, anyway.)

To get more milliamps, I should be safe in using 1.5v 'C' cells in place of the
AAs, shouldn't I?

If I plugged a battery pack into the external jack of my RCX 1.0, would the RCX
draw from both the internal and external batteries, or just the external?

Thanks,
Brian



Message has 2 Replies:
  Re: SHRIMP power
 
(...) Brian, My shrimp building has been on hold do to a move, but I was having a similar power issue. Splitting the motors between outputs helped. I believe the outputs are current limited (or thermal limited). (23 years ago, 9-Oct-01, to lugnet.robotics)
  Re: SHRIMP power
 
(...) Heh...ayup, six driving motors plus two steering motors takes a lot of juice. The solution to all our woes is here: (URL) the issue of free motor ports. Now, there is still the issue of burning through batteries, and thoguh I haven't explored (...) (23 years ago, 9-Oct-01, to lugnet.robotics)

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